University of Cambridge, Department of Engineering, Trumpington Street, Cambridge CB2 1PZ. (Received 2 December 1985; revised 9 June 1986)

Size: px
Start display at page:

Download "University of Cambridge, Department of Engineering, Trumpington Street, Cambridge CB2 1PZ. (Received 2 December 1985; revised 9 June 1986)"

Transcription

1 Clay Minerals (1987) 22, THE DISSOLUTION OF ASBESTOS FIBRES IN WATER JANET R. GRONOW University of Cambridge, Department of Engineering, Trumpington Street, Cambridge CB2 1PZ (Received 2 December 1985; revised 9 June 1986) A B S T R A C T : The interaction of chrysotile and crocidolite with water has been investigated in an attempt to identify the factors affecting the rate and the degree of dissolution of asbestos fibres within groundwater systems at landfill sites. Dissolution experiments were used to investigate rate laws and to obtain apparent activation energies for the dissolution of the two minerals. The activation energies related to transport-controlled processes, but as the overall dissolution occurred so slowly it was unlikely to be controlled by processes with such low activation energies. Congruent dissolution of both minerals tended to increase with temperature and time, suggesting that in the long-term environmental situation, congruent dissolution of these two asbestos minerals would occur. However these experiments show that, as the reaction was so slow, there is little likelihood of reduction of the asbestos pollution hazard by the complete dissolution of fibres on prolonged contact with natural waters. This investigation deals with the rate and degree of dissolution of asbestos fibres in water, and is related to the possible pollution of water supplies by asbestos waste deposited in landfill sites. Several authors (e.g. Harris & Grimshaw, 1971) have noted the high solubility of chrysotile, particularly in solutions of low ph. This suggests that there is a possibility that, on prolonged contact with water, asbestos fibres might disintegrate and be rendered harmless. For this reason, the aim of the investigation was to look at both the mechanism and the degree of dissolution of asbestos fibres in water and to relate the solubility of the fibres to the environmental situation. Most silicate minerals undergo incongruent dissolution at low temperatures. The rate of dissolution may be controlled by: (i) reaction of the unaltered mineral at the mineral-solution interface (Lagache, 1965); (ii) the diffusion rate of ions through a leached surface layer (Luce et al., 1972); the rate of diffusion of ions through a precipitated surface layer (Wollast, 1967; Helgeson, 1971). Minerals that are included in the general term asbestos fall into two groups. These are the serpentines, of which chrysotile (white asbestos) is the only fibrous form, and the amphibole group which includes crocidolite (blue asbestos), amosite (brown asbestos), tremolite, actinolite and anthophyllite. The slight misfit in the dimensions of the octahedral and tetrahedral sheets of chrysotile causes the mineral to roll carpet-like into fibres, with the brucite sheet on the outside; the average diameter of the chrysotile fibres is 300 A. The fibrous varieties of the amphiboles are not cylindrical but are formed with the fibre axis perpendicular to the crystallographic z-axis. Individual crocidolite fibre diameters are of the order of 200 A or less. Chrysotile may be represented by the structural formula Mg6Si4Oa 0(OH)s with some substitution of FC +, Fe 3 and Ca 2+ in octahedral sites. The formula Na2_3(Fe3+,A13+)2 (Fe2+, Mg2+)3SisO22(OH) The Mineralogical Society

2 22 Janet R. Gronow TABLE 1. Major element analysesofasbestossamples studied. Chrysotile Crocidolite SiO A FezO FeO l MgO CaO Na K20 0"01 0'06 H20-2'48 0"12 H20+ 13"81 2"80 Ti02 0'03 0"37 P2Os MnO CO F 0.03 Total less O = F 0.01 Total represents crocidolite, where K + may be substituted for Na + at the 'A' sites and Ca 2+ for Na + in octahedral sites and there may be some substitution of Fe, A13+ and Mg 2+ by Ti 4+ and Mn >. EXPERIMENTAL METHODS Initial characterization of samples The sample of chrysotile used was from Thetford, Canada, and was provided by Cape Asbestos Fibres Ltd. The crocidolite sample was from Cape Province, South Africa, and was provided by Turner Asbestos Fibres. Major element analyses of the samples are given in Table 1. Cell dimensions ofa = 5.31 ~,, b = 9.24 A, c = A and fl = ~ for chrysotile and a = 9.65/~, b = A, c = 9"65 and fl = ~ for crocidolite were found from X-ray powder photographs taken with a Gandolfi camera using Cu-Kct radiation. These agree closely with published data and were obtained using the computer program Cellpar (Prewitt, 1974) which provides a least-squares refinement of assumed cell parameters based on X-ray powder data. Sample pretreatment Samples of the two minerals were hand-picked, milled for 5-15 min and then sieved. The sieved products ( /~m) were washed several times with Aristar grade acetone. Under the transmission electron microscope, they consisted of well-opened bundles of fibres, 110 pm long.

3 Dissolution of asbestos fibres in water 23 There is no doubt that the pre-treatment of a solid sample has a large bearing on subsequent reaction kinetics and can produce changes in reaction rates of more than one order of magnitude (Boldyrev et al., 1979). Ball milling, apart from opening up the bundles of asbestos fibres and so increasing the surface area, may cause structural changes (Uehara, 1975) and it almost certainly increases the frequency of lattice defects at the surface of the sample. The changes in particle size and concomitant changes in surface area may affect the reaction in different ways. (1) A change in available surface area may modify the relative influence of nucleation and interfacial reaction. (2) Surface stresses and surface energy may be changed. This is likely to alter surface reactivity. An increase in the number of defects at the surface is likely to increase the number of potential reaction sites. (3) A variation in surface area may affect diffusion, which may change the rate of reaction if transport mechanisms have any part to play in the rate-controlling process. The preparation of mineral surfaces has been the subject of much controversy. There has been a suggestion that the fresh mineral surface produced by etching with an HF/HzSO4 solution may be fluorinated by this technique under certain circumstances (Perry et al., 1983; Berner et al., 1985). Ultrasonics were found to be unsatisfactory in this case because the resulting suspensions of the asbestos fibres contained flocs from which it was impossible to separate the fines. However, it is possible to assess the lattice damage produced in chrysotile on milling, by monitoring the intensity of various peaks in the IR spectrum of the mineral, as certain peaks have been shown to be sensitive to the effects of grinding (Harris, 1971). The spectrum obtained from the #m fraction showed that there was no significant disruption of the silicate lattice during sample preparation. The specific surface area of chrysotile prepared as described above was found to be 45.2 m 2 g-1 ; for crocidolite, the measured surface area was 24.7 m 2 g-1. DISSOLUTION EXPERIMENTS Water used for the dissolutions had a resistivity of at least 18 megohm-cm and was found to have no element present above the ten parts per billion level. Reaction was carried out in one litre Nalgene Teflon FEP bottles under CO2-free nitrogen. Through ports in each lid, three Tygon tubes were passed; a fourth port was used for ph measurement and was closed when not in use. One tube was for sampling and the other two were for nitrogen inlet and outlet. Two reaction jars containing 1 1 of water plus a Teflon-coated magnetic follower were placed in a plastic water-bath mounted on two magnetic stirrers. The temperature of the water-bath was kept constant, the solutions were stirred continuously and the ph was monitored using a glass-calomel combination electrode. The rate of mineral dissolution depends on ph (Luce et al., 1972), and it was necessary to use buffer solutions as the ph of the contact suspensions changed continuously as the hydrolysis of the mineral progressed. Buffers were used with reluctance because of concern about the participation of components of the buffer in the rate-limiting step. Buffers with negligible metal-buffer binding capacities were used (Good et al., 1966) M NN-bis(2- hydroxyethyl)-2-aminoethane sulphonic acid (BES) was used for solutions at ph 7, 0.05 M Tris (hydroxmethyl) aminomethane (TRIS) was used for ph 9, and 0.05 M Tris (hydroxmethyl) aminomethane citrate (monobasic TRIS citrate) was used for ph 4.

4 24 Janet R. Gronow 500 mg of fibres were added to the reaction vessel and 10 ml aliquots of the suspension removed after 15 min and at set time intervals thereafter. Each aliquot was immediately filtered through a 0.1 #m Millipore filter and acidified with Ultra-grade HC104 before analysis by atomic absorption spectroscopy for Mg and Si and, for crocidolite, also for Fe. The filters were dried and kept for X-ray photoelectron spectroscopy (XPS). In the absence of COz, the amount of ferrous iron in solution is controlled by the solubility of Fe(OH)2, which is ~ 104 at ph 7, so dissolutions were carried out under CO2-free nitrogen. In the ph range 6-8, the amount of ferric iron in solution is limited by the low solubility of Fe(OH)3 (4 x x 10-6 ppm Fe) (Mason, 1966) but the influence of other dissolved constituents, or the formation of complex ions, can cause considerable deviation from theoretical solubilities. The possibility of hydrous ferric oxide formation during the crocidolite dissolution experiments was relevant for four reasons. (1) It is possible that reactions involving iron could have played a part in the rate-controlling process of dissolution (Siever & Woodford, 1979). (2) As some colloidal iron could have been removed during filtration, it was decided not to use iron to monitor the reaction. (3) It is known that colloidal iron adsorbs such ions as Si. For this reason a dialysis bag, as used by Wildman et al. (1968), was suspended in the crocidolite reaction solutions. The solution inside this was analysed without filtration at the end of each experiment. Generally there was no significant trend in the differences between the Mg and Si concentrations in the final filtered solution and in the dialysis bag, indicating little adsorption of Mg or Si onto any colloids formed after dissolution from the mineral surface. (4) Iron colloids could have interfered with XPS of the residue on the filters. OBSERVATIONS Both chrysotile and crocidolite were found to dissolve incongruently and, in all cases, by 1024 h some sort of equilibrium was approached. Table 2 shows the theoretical number of TABLE 2. Calculated proportion of one surface layer removed after dissolution Theoretical Actual p.p.m, in solution Calculated proportion of one layer p.p.m./1 layer Temp Mg Si Mg Si Mg Si Mg Si ph (~ Mg Si after 170 h after 1024 h after 170 h after 1024 h Chrysotile Crocidolite

5 Dissolution of asbestos fibres in water 25 surface layers removed after each experiment, which gives an indication of the degree of dissolution which had occurred, but it is not assumed that reaction actually took place uniformly over the surface of the mineral fibres. TEM of fibres which had undergone 1024 h dissolution produced no evidence of changes at the surface of the minerals and there was no reduction in the intensity of diffraction patterns from bundles of parallel fibres. Both observations are to be expected if reaction did in fact occur at the limited rate indicated by Table 2. The resolution of the scanning electron microscope available was insufficient to obtain an indication of the nature of the surface reaction. SEM and X-ray microanalysis of chrysotile on which the lichen Lecanora atra had been growing and actively secreting oxalic acid (Wilson et al., 1981) has shown evidence of an X-ray amorphous silica gel layer up to 100 pm thick on the surface of fibre bundles. But work by Holdren & Berner (1979) and Berner et al. (1980) on feldspars, amphiboles and pyroxenes, and by Fung & Sanipelli (1982) on microcline, resulted in scanning electron micrographs of mineral surfaces with etched patterns, which suggested that the chemical reaction at the interface, and not diffusion, was the rate-limiting process. The Mg: Si ratios obtained from XPS of the filters from chrysotile and crocidolite dissolutions at ph 4 are given in Table 3, together with the Fe:Si ratio for crocidolite. Analysis depths were ~22 A for Mgls, 56 A for Si2p and 42 A for Fe. According to Luce et al. (1972), cases where transport is limited by diffusion of the reacting species through a leached mineral surface layer lead to so-called parabolic kinetics, where the quantity of species per unit area of mineral surface found in solution is proportional to the square root of the time in solution. The chrysotile analysis in Table 3 indicates the presence of an Mg-depleted layer, which suggests that dissolution at ph 4 may be diffusion controlled. Fig. 1 demonstrates that this was the only chrysotile dissolution to show parabolic kinetics, but then, as can be seen from Table 2, it was the only chrysotile dissolution in which more than one theoretical surface layer was removed and therefore was the only dissolution in which a leached layer could have been achieved. The fibres from the low-ph chrysotile dissolution were investigated in more detail by XPS to see if there was any shift in the position of silicon peaks which might indicate a difference in the structure of the silicate framework in the leached layer, but none was obvious. TABLB 3. XPS of fibres from low-ph dissolutions Contact solution (mole dm -3 x 10-4) Time (h) Mg : Si Fe : Si Mg Si Chrysotile Crocidolite ' ' " '50 0" '

6 26 Janet R. Gronow G" I o 25 x r 20 phi, ~15 10 _- ~/ 6oCJ ~ { hour) 1/2 ph7 25% ph9 FIG. 1. Chrysotile dissolution: Mg concentration in contact solution to indicate 'parabolic kinetics'. However, this is reasonable as the mineral has a layer structure and incongruent dissolution may not lead to a significant change in the structure of the tetrahedral silicate sheet. If the pattern of incongruent dissolution suggested by the concentrations of Mg and Si in the crocidolite contact solution (Table 3) was followed, a leached layer approximately one unit-cell thick over the mineral surface after 50 h would be expected, producing an Mg: Si ratio of However no such layer was evident from the XPS analysis. This suggests that reaction occurred at discrete sites rather than in a uniform layer. The Fe: Si ratios produced by XPS of leached crocidolite were no higher than expected from the atomic ratios of the unleached mineral and do not indicate an Fe-rich layer on the surface of the crocidolite fibres. In fact the analysis showed no surface layer on any sort, neither leached nor precipitated, indicating that the rate-limiting step of the dissolution process at 50 h could not be diffusion through a surface layer. DISCUSSION The dissolution of a solid may be divided into the following processes (Bircumshaw & Riddiford, 1952): (i) diffusion ofthe reacting species towards the surface; (ii) adsorption onto the surface; (iii) reaction at the surface; (iv) desorption of products; (v) diffusion of products away from the surface. Processes (i) and (v) are transport phenomena, (ii), (iii) and (v) are

7 - C]a[n+] Dissolution of asbestos fibres in water 27 surface reactions. Generally (ii) and (v) are too fast to be rate-determining processes, so the rate-limiting step is most~ikely to be either (i), (iii) or (v). Heterogeneous reactions may be divided into three types: (1) Transport-controlled processes, where the rate of chemical reaction at the reaction interface is very much faster than the rate of transport of the reactant to, or the product from, the surface. (2) Chemically controlled processes, where the rate of the chemical reaction is much slower than either of the transport processes. (3) Intermediate situations, where both processes have similar rates. The general equation describing the type (3) reaction above, involving the dissolution from a surface of area S into a fluid of volume V, is: Vdc J = -S d-t = kt(c' - C) = kc(c ~ - C') n (1) where J is the mass flux of a species C into the bulk solution (mole m -2 h-l), C' is the surface concentration, C is the bulk fluid concentration and k t is the mass transport coefficient for species C. C~ is the equilibrium concentration at the surface and kc is the reaction rate constant, the dimensions of which depend on the value of n. Reaction types (1) and (2) are limiting cases of this: in type (1) reactions the chemical reaction rate is much faster than the transport rate and, because J remains finite, (C' s - C') must be small, i.e. C's --- C'. So equation (1) becomes: Vdc J- - kt(c~ - C) (2) Sdt Similarly, in type 2 reactions, (C' - C) will be small, i.e. C' - C and equation (1) becomes: Vdc J- S dt - k~(c; - Cy (3) This implies that a reaction order other than unity indicates that the dissolution is controlled by the chemical reaction at the surface, but this is not necessarily so in a multi-component system. CHRYSOTILE DISSOLUTION The rate of a dissolution may be measured as a change in concentration of a species as a function of time. The rate law for dissolution may be given by: J = k[c e - b (4) where k is the reaction rate parameter, C is the concentration of the measured species in the bulk solution, Ce is the steady-state Concentration to which the solution tends, and a and b are the reaction orders with respect to species C and hydrogen ion concentrations respectively. Taking logs of equation (4) and keeping ph constant gives: log J = log k' + a log [Ce - C] (5) where k' = k[h b. A plot of log J vs log [Ce - C] has a slope of a, the reaction order with respect to C. For Mg, values of J were obtained from the slope of the plot of Mg concentration vs time at constant ph (Fig. 2).

8 28 Janet R. Gronow 44.6~ magnesium ~"25' "U E20 i sample surface area 22.5m t 15 silicon 10. Z,L.6~ ~ 6.0~ C 0 20 z.o (h) FIG. 2. Chrysotile dissolution at ph 7: Mg and Si concentrations in contact solution. It is difficult to determine the point at which a mineral reaction nears equilibrium, since small changes in concentration over long periods of time are difficult to detect. Plummer & Mackenzie (1974) described a method of estimating mineral solubility from the rate at which equilibrium is approached during dissolution. They found that, provided the surface reactions did not change with time and that the time to half saturation was greater than 10 h, extrapolation to infinite time of a plot of species concentration vs (time) --~ produced a good estimate of the species equilibrium concentration. It was not possible to use this method to estimate the Mg equilibrium concentration for chrysotile dissolution, as the time to half saturation was < 10 h. However, it can be seen from Table 2 that in all chrysotile dissolutions at ph 7 less than one theoretical surface layer was removed and, as is indicated later, the activation energy for Si dissolution appears to be greater than that for the dissolution of Mg. This may justify taking the amount of Mg in one surface layer as the Mg equilibrium value to which the solution tends, assuming that the slower release of Si from the tetrahedral sheet limits further Mg dissolution in sheets beneath this. Applying this method, values of log J vs log [Mge - Mg] were obtained and plotted in Fig. 3, to give a reaction order of 4.1 _+ 1.0 with respect to Mg. The linear least-squares analysis used by Latham & Burgess (1977) was employed in all these calculations to find the best straight-line fit for the data obtained. The method of Plummer & Mackenzie (1974) was used to estimate the Si equilibrium concentration in the chrysotile solutions, as time to half saturation exceeded 10 h; this gave a reaction order of 3.5 _+ 0.9 with respect to Si (Fig. 3).

9 Dissolution of asbestos.fibres in water 29 magnesium silicon reaction order 3,8/ / 7 / reoction order 3.3 i 5 reaction order Iog[C e - C] FIG. 3. Chrysotile dissolution at ph 7: reaction orders with respect to Mg and Si. The effect of ph on chrysotile dissolution can be seen in Fig. 4. Measurement of log J at different ph values provides a value for b, the reaction order with respect to ph. This was obtained by least-squares analysis of values of log Jat 25~ at different times for both Mg and Si. For Mg, the rate of the reaction was found to be approximately proportional to [H 1/3 and 95 ph & H 40 Si f o 80 X "( / sample surface area 22.5m 2 / 351 /..... _... ph72mg 20 /'" ph90 Mg ph. 7.2 Si "~--'-~-- ph /,0 hours FIG. 4. Chrysotile dissolution at 25~ concentration of Mg and Si in contact solution.

10 30 Janet R. Gronow the dissolution with respect to Si approximately proportional to [H+] 2/3. There was a trend in the value of reaction order with time ( for Mg and for Si) which indicates that log J should strictly have been measured at constant distance from equilibrium, but this was not possible with the data available. That none of the reaction order values obtained were unity suggests, but in no way proves, that the dissolution was surface-reaction-rate-, rather than transport-controlled. Taking logs of the Arrhenius equation gives log k' = log A - EA/2.303RT (6) where k' is the reaction rate constant given in equation (5) and EA is the apparent activation energy for the reaction. The reaction rate was measured when Mg concentrations were at a constant distance from equilibrium, and values of log J vs 1/T(K) were used to obtain an apparent activation energy for the dissolution of Mg of ~ 27 kj mole -1. Analysis of the initial reaction rate gave the much lower value of 9 kj mole -1. These values lie on either side of the 22.9 kj mole -1 obtained by Choi & Smith (1971), which they consider to be indicative of diffusion-controlled processes, since diffusion of ions through liquids have activation energies of the order of 20 kj mole -1. Analysis of the initial reaction rate gave a value of 32 kj mole- ~ for the apparent activation energy of Si removal. Judging by the interval estimates calculated with 90~ probability for the slopes of the linear least-squares analyses, the error on these values could have been as much as 50~. Since the dissolution of the first layer of Mg is not dependent on the removal of Si, it is feasible to obtain different activation energies for Mg and Si dissolution initially. However, after the removal of the freely available Mg on the surface, any other Mg reaction may be limited by one of two factors; the exposure of fresh Mg, which will depend on the mechanism with the higher activation energy which limits Si dissolution, or by diffusion of Mg ions through the silicate layer. The apparent activation energies obtained relate only to reactions at ph 7. The XPS results suggest that, at a lower ph, Mg dissolution may be controlled by diffusion through a leached layer, and the activation energy for this process is likely to be considerably higher (of the order of 100 kj mole- i). The dissolution of Si at low ph was initially slower than that of Mg, which suggests that Si dissolution may be limited by the surface reaction of the tetrahedral silicate sheet during this stage. However the overall reaction rate at ph 4 was markedly higher than at ph 7, which suggests that the activation energy at ph 4 might be lower than at ph 7, unless the pre-exponential factor A in equation (6) was solely responsible for the difference. So it is possible that the overall reaction at ph 7 is controlled by a process with a considerably higher activation energy than the values obtained here. CROCIDOLITE DISSOLUTION Values of the reaction rate for crocidolite dissolution with respect to both Mg and Si were found from Fig. 5. A value of was obtained for the reaction order with respect to Mg. The method of Plummer & Mackenzie (1974) was used to estimate both the Mg and Si equilibrium values and gave a reaction order of with respect to Si (Fig. 6). The dissolution profiles of crocidolite with respect to Mg at 25~ and different ph values can be seen in Fig. 7. The reaction order with respect to ph was found to be The trend in reaction order with time ( ) again indicates that the reaction rate should strictly have been measured at constant distance from equilibrium.

11 Dissolution of asbestos fibres in water 31 t I / ' Z./-,.6~ Si J 6 7' X o? 66i -6 ~5~ I I t Z.Z,.6~ Mg / ~ _-~ ~ Si 251~ Mg / 6.0~ Mg ~ Si hours FIG. 5. Crocidolite dissolution at ph 7 : concentration of Mg and Si in contact solution. Sample surface area 12.5 m E. ro=1.8 ro=20 ~8 0 I ro = 212 /,Z,.6 ~ C Si ro = ~ Si /*Z,.6~ Mg 6.0% Mg 38 /,.0 L,.2 /,/, Iog[C e- C] FIG. 6. Crocidolite dissolution at ph 7: reaction order (ro) with respect to Mg and Si. Fig. 7 shows that the response of Si dissolution rate to ph is non-linear, suggesting that there may be a different dissolution mechanism at different values of ph. This non-linear dependence on ph was also noted by Schott et al. (1981) when investigating the dissolution of Si from enstatite and diopside. An apparent activation energy for the removal of Mg from crocidolite of 28 kj mole-~ was obtained from values of log J at ph 7 at different temperatures and at equal distances from

12 32 Janet R. Gronow ph 4.0 Si 8 ~-7 I O x6 O') 'E ph 8.9 Si.- -".- -" ph l,,o Mg " " p H_7,2 Mg 1,r "/t /z r/ / ' ph 8,9 Mg f 0 20 L hours FIG. 7. Crocidolite dissolution at 25~ : concentration of Mg and Si in contact solution. Sample surface area 12.5 m 2. equilibrium. A value of 17 kj mole -1 was obtained from the initial reaction rates. These values are low enough to indicate that the removal of Mg from the mineral is transport controlled. This suggests that the loss of the other metal ions in the 'I beam sandwich' may also be transport-controlled, provided that the oxidation of Fe(II) from the MI site does not play a part in the dissolution mechanism and that the differences in the Madelung site energies are not significant. For Si, values of log J for two different temperatures at the same distance from equilibrium gave an apparent activation energy of 27 kj mole -1. Analysis of the initial reaction rates of Si dissolution at different temperatures produced an apparent activation energy of 32 kj mole- 1. These values refer to dissolution at ph 7 only and were of the same order of magnitude as those obtained by Choi et al. (1974), but were only approximately one half of those obtained by Schott et al. (1981) for the dissolution of non-fibrous iron-free amphiboles. CONCLUSIONS There is little doubt that the activation energies obtained here relate to transport-controlled processes. However, it is suggested that the overall reaction proceeds too slowly to be controlled by processes with such low activation energies, when one considers that at neutral and high ph less than the equivalent of one surface layer had been removed after one and a half months reaction time.

13 Dissolution of asbestos fibres in water 33 On comparing these results with both the methods and results of other workers (e.g. Choi et al., 1974; Grandstaff, 1977; Schott et al., 1981 ; Chou & Wollast, 1984) it appears that it is the pre-treatment of the minerals which is the critical factor. As the calculations in these experiments were the result of the first sixty hours reaction, it may be the dissolution of ultrafine particles produced by comminution which was measured. This is probably also the reason for the discrepancies in this work in the apparent activation energies of Mg dissolution calculated using the initial reaction rates and at equal distance from equilibrium. It has also been suggested (Chou & Wollast, 1984) that the presence of fine-grained material and highly strained areas is the reason for the observed 'parabolic dissolution kinetics' proposed by Luce et al. (1972). Heterogeneous reactions involve the formation of a reaction border, resulting from an inefficiency in transport processes, or from chemical reactivity. The latter may involve two processes, that of nucleation and the reaction at the interface, and all three factors are affected by surface conditions. The course of a reaction depends on the way in which potential reaction sites are distributed. Nucleation is only possible when some sort of surface reaction has proceeded to a sufficient extent, for enough nucleus-forming species to be released. The rate of nucleation varies differently with respect to the rate of the interfacial process and may not always be rate-limiting. Although the actual surface area may affect the degree to which transport processes control the overall process, the results suggest that the surface of the minerals is in a condition in which the surface energy of sufficient potential sites is high enough that the chemical reaction is no longer the rate-limiting process, but that as the number or energy of available new sites decreases so the progress of the chemical reaction may become rate-limiting. XPS results indicate that the dissolution of chrysotile may occur through an Mg-depleted surface layer, but no such layer formed on the crocidolite surface. However, for both chrysotile and crocidolite there is a tendency towards congruent dissolution with increasing temperature and increasing time. This suggests that, in the long term, there will be a slow congruent dissolution of both types of asbestos in water. The dissolution of crocidolite may be slowed further, under suitable conditions, by the precipitation of ferric oxides on the surface. Seiver & Woodford (1979) found that oxidation of Fe in mafic minerals did not occur within the existing structure and therefore did not contribute to the dissolution process during oxidation, but could reduce it by the formation of an unreactive coating. Chrysotile dissolution is more rapid at low ph than at high ph but also closer to congruency, presumably since the initially faster removal of Mg ions exposes a large area of the tetrahedral silicate sheet to hydrolytic attack, so it is unlikely that a silica relic, devoid of metal cations, would remain in suspension. Even if this was the case, research indicates that it is the shape of the fibre and not its chemical composition which is responsible for the carcinogenic properties of asbestos, so the hazard would not be reduced by the loss of Mg from the structure. In the environmental context the system is likely to be an open one, so approaching equilibrium may not always be a factor in the dissolution rate. All asbestos deposited in landfills is likely to have undergone a manufacturing process. However, the pretreatment of the mineral is unlikely to have much effect on the long-term dissolution rate; the conditions in which the fibres are retained will be of most importance. For example, ph will effect chrysotile dissolution most dramatically and Eh is likely to have more control over the dissolution of Fe-rich crocidolite. The present work shows that only in extreme conditions of low ph will there be any chance of the complete disintegration of the minerals within a groundwater system.

14 34 Janet R. Gronow ACKNOWLEDGEMENTS This work was carried out under the direction of the Thames Water Authority as part of a Natural Environment Research Council CASE Studentship. I would like to thank my supervisor, Dr C. V. Jeans for his support and advice during that time and Dr A. A. Hodgson for his helpful review of the paper. REFERENCES BERNER R.A., HOLDREN G.R. & SCHOTT J. (1985) Surface layers on dissolving silicates. Geochim. Cosmochim,. Acta 43, BERYER R.A., SJOBERG E.L., VELBEL M.A. & KROM M.D. (1980) Dissolution of pyroxenes and amphiboles during weathering. Science 207, BIRCUMSnAW L.L. & RIDDIFORD A.C. (1952) Transport control in heterogeneous reactions. Quarterly Review Chem. Sac. London 6, BOLDYREV V.V., BULLENS M. & DELMON B. (1979) Studies in Surface Science and Catalysis 2 Elsevier, Amsterdam, 226 pp. Cnoi I., MALGnAN S.G. & SMITH R.W. (1974) The dissolution kinetics of fibrous amphibole minerals in water. Proc. Int. Symp. Water-rock Interaction, Czechoslovakia, Cnoi I. & SMITH R.W. (1971) Kinetic study of dissolution of asbestos fibres in water. J. Colloid Interface Sci. 40, CHOU L. & WOLLAST R. (1984) Study of the weathering of albite at room temperature and pressure with a fluidized bed reactor. Geochim. Cosmochim. Acta 48, FtJNG P.C. & SANIPELLI G.G. (1982) Surface studies of feldspar dissolution using surface replication combined with electron microscopic techniques. Geochim. Cosmochim. Acta 46, GOOD N.E., WINGET G.D., WINTER W., CONNOLLY T.N., IZAWA S. & SINGH R.M.M. (1966) Hydrogen ion buffers for biological research. Biochemistry 5, GRANDSTAFF D.E. (1977) Some kinetics of bronzite orthopyroxene dissolution. Geochim. Cosmochin. Acta 41, GRONOW J.R. (1983) The identification and reaction of asbestos waste m groundwater systems. PhD thesis, University of Cambridge. HARRIS A.M. (1971) The effects of grinding on the structural and thermal properties of chrysotile asbestos fibres. Proc. 2nd Int. Conf. on the Physics and Chemistry of Asbestos Minerals, Louvain, paper 2:2A. HARRIS A.M. & GRIMSrlAW R.W. (1971) The leaching of ground chrysotile. Proc. 2ndInt. Conf. on the Physics and Chemistry of Asbestos Minerals, Louvain, paper 3:2B. HELGESON H.C. (1971) Kinetics of mass transfer among silicates and aqueous solutions. Geochim. Cosmochim. Acta 35, HOLDREN G.R. & BERNER R.A. (1979) Mechanics of feldspar weathering-i Experimental studies. Geochim. Cosmochim. Acta 43, LAGACHE M. (1965) Contribution gt 16tude de l'alt6ration des feldspath, dans l'eau entre 100 et 200~ sous diverses pressions de CO2 et application ~ la synth6se des mineraux argilleux. Bull.. Soc. Ft. Miner. Crist. 88, LATHAM J.L. & BURGESS A.E. (1977) Elementary Reaction Kinetics, 3rd edition. Butterworths, London. LUCE R.W., BARTLETT R.W. & PARKS G.A. (1972) Dissolution kinetics of magnesium silicates. Geochim. Cosmochim. Acta 36, MASON B. (1966) Principles of Geochemistry, 3rd edition. John Wiley and Sons, Chichester and London. PERRY D.L., TSAO L. & GAUGLER K.A. (1983) Surface study of HF- and HF/H2SO4 treated feldspar using Auger electron spectroscopy. Geochim. Cosmochim. Acta 47, PLUMMER L.N. & MACKENZIE F.T. (1974) Prediction of mineral solubility from rate data: application to the dissolution of magnesium calcites. Am. J. Sci. 274, PLUMMER L.N. & WIGLEY I.M.L. (1976) Dissolution of calcite in CO2 saturated solutions at 25~ and one atmosphere total pressure. Geochim. Cosmochim. Acta 40, PREWITT C.T. (1974) Cellpar, a cell refinement program. Dept. of Earth and Space Sciences, New York State University. SCHOTr J., BERNER R.A. & SJOBERG E.L. (1981) Mechanism of pyroxene and amphibole weathering. I. Experimental studies on iron free minerals. Geochim. Cosmochim. Acta 45,

15 Dissolution of asbestos fibres in water 35 SIEVER R. & WOODFORD N. (1979) Dissolution kinetics and the weathering of mafic minerals. Geochim. Cosmochim. Acta 43, UEHARA Y. (1975) Structural changes in iron oxides by ball milling in different media. Bull. Chem. Soc. Japan 48, WILDMAN W.E., JACKSON M.L. & WHITTIG L.D. (1968) Serpentinite rock dissolution as a function of carbon dioxide pressure in aqueous solution. Am. Miner. 53, WILSON M.J., JONES n. & MCHARDY W.J. (1981) The weathering of serpentinite by Lecanora atra. Lichenologist 13, WOLLAST R (1967) Kinetics of mass transfer among silicates and aqueous solutions. Geochim. Cosmochim. Acta 31,

CHEMICAL KINETICS (RATES OF REACTION)

CHEMICAL KINETICS (RATES OF REACTION) 1 CHEMICAL KINETICS (RATES OF REACTION) Introduction Chemical kinetics is concerned with the dynamics of chemical reactions such as the way reactions take place and the rate (speed) of the process. Collision

More information

The interaction of Cu(100)-Fe surfaces with oxygen studied with photoelectron spectroscopy. I

The interaction of Cu(100)-Fe surfaces with oxygen studied with photoelectron spectroscopy. I 5 The interaction of Cu(100)-Fe surfaces with oxygen studied with photoelectron spectroscopy. I Mg Kα excited photoemission. Abstract The oxidation of Cu(100)-Fe surfaces was studied using XPS. Surfaces

More information

Asbestos. General information

Asbestos. General information Asbestos General information Key Points Fire Non flammable and non combustible under normal conditions Chemically inert under normal conditions. Resistant to most solvents, acids and alkalis In the event

More information

Corrosion. Chemistry. Grade 10-12 LEARNING OUTCOMES DESCRIPTION MATERIALS READINESS ACTIVITIES. Science

Corrosion. Chemistry. Grade 10-12 LEARNING OUTCOMES DESCRIPTION MATERIALS READINESS ACTIVITIES. Science Science Grade 10-12 Classroom Individual reading DESCRIPTION The characteristic red color of Prince Edward Island soil can be explained by a chemical reaction. The process is known as corrosion or rusting.

More information

Reaction Rates and Chemical Kinetics. Factors Affecting Reaction Rate [O 2. CHAPTER 13 Page 1

Reaction Rates and Chemical Kinetics. Factors Affecting Reaction Rate [O 2. CHAPTER 13 Page 1 CHAPTER 13 Page 1 Reaction Rates and Chemical Kinetics Several factors affect the rate at which a reaction occurs. Some reactions are instantaneous while others are extremely slow. Whether a commercial

More information

Asbestos Presence in a Factory that Produced Asbestos-Containing Products

Asbestos Presence in a Factory that Produced Asbestos-Containing Products Asbestos Presence in a Factory that Produced Asbestos-Containing Products Hana Fajkovi Department of Geology, Faculty of Science, University of Zagreb, Horvatovac 95, 10000 Zagreb, Croatia, e-mail: (hanaf@geol.pmf.hr)

More information

Factors Affecting Precipitation of Calcium Carbonate

Factors Affecting Precipitation of Calcium Carbonate Factors Affecting Precipitation of Calcium Carbonate John A. Wojtowicz Chemcon Laboratory tests with clear solutions showed that precipitation of calcium carbonate does not occur in the ph range 7.5 to

More information

IB Chemistry. DP Chemistry Review

IB Chemistry. DP Chemistry Review DP Chemistry Review Topic 1: Quantitative chemistry 1.1 The mole concept and Avogadro s constant Assessment statement Apply the mole concept to substances. Determine the number of particles and the amount

More information

THE USE OF OZONATED HF SOLUTIONS FOR POLYSILICON STRIPPING

THE USE OF OZONATED HF SOLUTIONS FOR POLYSILICON STRIPPING THE USE OF OZONATED HF SOLUTIONS FOR POLYSILICON STRIPPING Gim S. Chen, Ismail Kashkoush, and Rich E. Novak AKrion LLC 633 Hedgewood Drive, #15 Allentown, PA 1816, USA ABSTRACT Ozone-based HF chemistry

More information

Solidification, Crystallization & Glass Transition

Solidification, Crystallization & Glass Transition Solidification, Crystallization & Glass Transition Cooling the Melt solidification Crystallization versus Formation of Glass Parameters related to the formaton of glass Effect of cooling rate Glass transition

More information

Crust: low density rocks. Mantle: high density rocks. Core: very high density metal. core

Crust: low density rocks. Mantle: high density rocks. Core: very high density metal. core Crust: low density rocks Mantle: high density rocks Core: very high density metal core mechanical) layering mechanical layers lithosphere: rigid & strong asthenosphere: plastic & weak mesosphere: plastic

More information

Balancing Reaction Equations Oxidation State Reduction-oxidation Reactions

Balancing Reaction Equations Oxidation State Reduction-oxidation Reactions Balancing Reaction Equations Oxidation State Reduction-oxidation Reactions OCN 623 Chemical Oceanography Balanced chemical reactions are the math of chemistry They show the relationship between the reactants

More information

Steel Making Prof. Deepak Mazumdar Prof. S. C. Koria Department of Materials Science and Engineering Indian Institute of Technology, Kanpur

Steel Making Prof. Deepak Mazumdar Prof. S. C. Koria Department of Materials Science and Engineering Indian Institute of Technology, Kanpur Steel Making Prof. Deepak Mazumdar Prof. S. C. Koria Department of Materials Science and Engineering Indian Institute of Technology, Kanpur Module No. # 01 Lecture No. # 10 Modern Steelmaking I, Oxygen

More information

Lecture 11. Etching Techniques Reading: Chapter 11. ECE 6450 - Dr. Alan Doolittle

Lecture 11. Etching Techniques Reading: Chapter 11. ECE 6450 - Dr. Alan Doolittle Lecture 11 Etching Techniques Reading: Chapter 11 Etching Techniques Characterized by: 1.) Etch rate (A/minute) 2.) Selectivity: S=etch rate material 1 / etch rate material 2 is said to have a selectivity

More information

REMOVAL OF PHOSPHATE FROM WASTEWATER USING LOW-COST ADSORBENTS

REMOVAL OF PHOSPHATE FROM WASTEWATER USING LOW-COST ADSORBENTS International Journal of Engineering Inventions ISSN: 2278-7461, www.ijeijournal.com Volume 1, Issue 7 (October2012) PP: 44-50 REMOVAL OF PHOSPHATE FROM WASTEWATER USING LOW-COST ADSORBENTS Dr. C.R.Ramakrishnaiah

More information

Chemistry 111 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium

Chemistry 111 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium Chemistry 111 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium Introduction The word equilibrium suggests balance or stability. The fact that a chemical reaction

More information

CHEMICAL EQUILIBRIUM

CHEMICAL EQUILIBRIUM Chemistry 10 Chapter 14 CHEMICAL EQUILIBRIUM Reactions that can go in both directions are called reversible reactions. These reactions seem to stop before they go to completion. When the rate of the forward

More information

Silica Over-Saturation, Precipitation, Prevention and Remediation In Hot Water Systems Edited By Dave Peairs, Cal Water, Technical Director

Silica Over-Saturation, Precipitation, Prevention and Remediation In Hot Water Systems Edited By Dave Peairs, Cal Water, Technical Director Silica Over-Saturation, Precipitation, Prevention and Remediation In Hot Water Systems Edited By Dave Peairs, Cal Water, Technical Director Background Silica scaling becomes a problem when any hot water

More information

Phosphate Recovery from Municipal Wastewater through Crystallization of Calcium Phosphate

Phosphate Recovery from Municipal Wastewater through Crystallization of Calcium Phosphate Phosphate Recovery from Municipal Wastewater through Crystallization of Calcium Phosphate A. Alamdari, Ph.D. * and S. Rohani, M.Sc. * Department of Chemical Engineering, School of Engineering, Shiraz University,

More information

AP CHEMISTRY CHAPTER REVIEW CHAPTER 11: RATE OF REACTION

AP CHEMISTRY CHAPTER REVIEW CHAPTER 11: RATE OF REACTION AP CHEMISTRY CHAPTER REVIEW CHAPTER 11: RATE OF REACTION You should understand the definition of reaction rate, as well as how rates might be measured in a laboratory setting. You should know the difference

More information

Effect of Ni Content in a Low Alloy Steel on the High Temperature Oxide Scale Adherence

Effect of Ni Content in a Low Alloy Steel on the High Temperature Oxide Scale Adherence 52 China Steel Technical Report, Effect No. of Ni 21, Content pp. 52-58, in a Low (2008) Alloy Steel on the High Temperature Oxide Scale Adherence Effect of Ni Content in a Low Alloy Steel on the High

More information

Heterogeneous Catalysis and Catalytic Processes Prof. K. K. Pant Department of Chemical Engineering Indian Institute of Technology, Delhi

Heterogeneous Catalysis and Catalytic Processes Prof. K. K. Pant Department of Chemical Engineering Indian Institute of Technology, Delhi Heterogeneous Catalysis and Catalytic Processes Prof. K. K. Pant Department of Chemical Engineering Indian Institute of Technology, Delhi Module - 03 Lecture 10 Good morning. In my last lecture, I was

More information

Lecture 7: Oxidation of manganese and carbon. Key words: Solidification of steel, decarburization, BOF steelmaking

Lecture 7: Oxidation of manganese and carbon. Key words: Solidification of steel, decarburization, BOF steelmaking Lecture 7: Oxidation of manganese and carbon Contents: Behaviour of manganese Oxidation of manganese Reduction of manganese Oxidation of carbon Rimming reaction Illustration Key words: Solidification of

More information

APPENDIX B: EXERCISES

APPENDIX B: EXERCISES BUILDING CHEMISTRY LABORATORY SESSIONS APPENDIX B: EXERCISES Molecular mass, the mole, and mass percent Relative atomic and molecular mass Relative atomic mass (A r ) is a constant that expresses the ratio

More information

= 1.038 atm. 760 mm Hg. = 0.989 atm. d. 767 torr = 767 mm Hg. = 1.01 atm

= 1.038 atm. 760 mm Hg. = 0.989 atm. d. 767 torr = 767 mm Hg. = 1.01 atm Chapter 13 Gases 1. Solids and liquids have essentially fixed volumes and are not able to be compressed easily. Gases have volumes that depend on their conditions, and can be compressed or expanded by

More information

THE NWF WATER PURIFICATION PROCESS FRESH WATER IN A NATURAL WAY. Esko Meloni Ferroplan Oy

THE NWF WATER PURIFICATION PROCESS FRESH WATER IN A NATURAL WAY. Esko Meloni Ferroplan Oy THE NWF WATER PURIFICATION PROCESS FRESH WATER IN A NATURAL WAY Esko Meloni Ferroplan Oy 1 The NWF Water Purification Process: list of contents 1. NWF biological purification of groundwater Iron and manganese

More information

GEOL 2311 Midquarter Exam I Name Crystal Chemistry Score: / 100

GEOL 2311 Midquarter Exam I Name Crystal Chemistry Score: / 100 GEOL 2311 Midquarter Exam I Name Crystal Chemistry Score: / 100 1. Chose a subdiscipline of geology and describe how mineralogy plays a central role in that field. (2 pts) Looking for reasonable answers

More information

Chapter 5: Diffusion. 5.1 Steady-State Diffusion

Chapter 5: Diffusion. 5.1 Steady-State Diffusion : Diffusion Diffusion: the movement of particles in a solid from an area of high concentration to an area of low concentration, resulting in the uniform distribution of the substance Diffusion is process

More information

1A Rate of reaction. AS Chemistry introduced the qualitative aspects of rates of reaction. These include:

1A Rate of reaction. AS Chemistry introduced the qualitative aspects of rates of reaction. These include: 1A Rate of reaction AS Chemistry introduced the qualitative aspects of rates of reaction. These include: Collision theory Effect of temperature Effect of concentration Effect of pressure Activation energy

More information

CHEMICAL PRECIPITATION: WATER SOFTENING

CHEMICAL PRECIPITATION: WATER SOFTENING CHEMICAL PRECIPITATION: WATER SOFTENING Submitted to: Dr. Hashsham Research Complex Engineering Department of Civil and Environmental Engineering Michigan State University East Lansing, MI 4884 Authors

More information

h e l p s y o u C O N T R O L

h e l p s y o u C O N T R O L contamination analysis for compound semiconductors ANALYTICAL SERVICES B u r i e d d e f e c t s, E v a n s A n a l y t i c a l g r o u p h e l p s y o u C O N T R O L C O N T A M I N A T I O N Contamination

More information

Formation of solids from solutions and melts

Formation of solids from solutions and melts Formation of solids from solutions and melts Solids from a liquid phase. 1. The liquid has the same composition as the solid. Formed from the melt without any chemical transformation. Crystallization and

More information

GEOL 414/514 CARBONATE CHEMISTRY

GEOL 414/514 CARBONATE CHEMISTRY GEOL 414/514 CARBONATE CHEMISTRY Chapter 6 LANGMUIR SOLUBILITY OF CALCITE CaCO 3 in nature: calcite & aragonite Reaction with strong acid: CaCO 3 + 2H + Ca +2 + H 2 O + CO 2 Reaction with weak acid: CaCO

More information

Secondary Ion Mass Spectrometry

Secondary Ion Mass Spectrometry Secondary Ion Mass Spectrometry A PRACTICAL HANDBOOK FOR DEPTH PROFILING AND BULK IMPURITY ANALYSIS R. G. Wilson Hughes Research Laboratories Malibu, California F. A. Stevie AT&T Bell Laboratories Allentown,

More information

KINETIC TESTS AND RISK ASSESSMENT FOR ARD

KINETIC TESTS AND RISK ASSESSMENT FOR ARD th Presented at the 5 Annual BC Metal Leaching and ARD Workshop, December 9-10, 1998, Vancouver, Canada KINETIC TESTS AND RISK ASSESSMENT FOR ARD by Kevin A. Morin and Nora M. Hutt Minesite Drainage Assessment

More information

Chapter 1: Moles and equations. Learning outcomes. you should be able to:

Chapter 1: Moles and equations. Learning outcomes. you should be able to: Chapter 1: Moles and equations 1 Learning outcomes you should be able to: define and use the terms: relative atomic mass, isotopic mass and formula mass based on the 12 C scale perform calculations, including

More information

Honors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1. A chemical equation. (C-4.4)

Honors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1. A chemical equation. (C-4.4) Honors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1 1. 2. 3. 4. 5. 6. Question What is a symbolic representation of a chemical reaction? What 3 things (values) is a mole of a chemical

More information

CHAPTER 7 THE DEHYDRATION AND SWEETENING OF NATURAL GAS

CHAPTER 7 THE DEHYDRATION AND SWEETENING OF NATURAL GAS CHAPTER 7 THE DEHYDRATION AND SWEETENING OF NATURAL GAS Natural gases either from natural production or storage reservoirs contain water, which condense and form solid gas hydrates to block pipeline flow

More information

Chemical Vapor Deposition

Chemical Vapor Deposition Chemical Vapor Deposition Physical Vapor Deposition (PVD) So far we have seen deposition techniques that physically transport material from a condensed phase source to a substrate. The material to be deposited

More information

IUCLID 5 COMPOSITION AND ANALYSIS GUIDANCE DOCUMENT: IRON ORES, AGGLOMERATES [EINECS NUMBER 265 996 3, CAS NUMBER 65996 65 8] IRON ORE PELLETS

IUCLID 5 COMPOSITION AND ANALYSIS GUIDANCE DOCUMENT: IRON ORES, AGGLOMERATES [EINECS NUMBER 265 996 3, CAS NUMBER 65996 65 8] IRON ORE PELLETS IUCLID 5 COMPOSITION AND ANALYSIS GUIDANCE DOCUMENT: IRON ORES, AGGLOMERATES [EINECS NUMBER 265 996 3, CAS NUMBER 65996 65 8] IRON ORE PELLETS INTRODUCTION Each REACH registrant is required to file its

More information

Paper No. 4071 APPLICATION OF EQCM TO THE STUDY OF CO2 CORROSION

Paper No. 4071 APPLICATION OF EQCM TO THE STUDY OF CO2 CORROSION Paper No. 471 APPLICATION OF EQCM TO THE STUDY OF CO2 CORROSION Yang Yang, Bruce Brown and Srdjan Nešić Institute for Corrosion and Multiphase Technology, Department of Chemical and Biomolecular Engineering

More information

UNIVERSITA` degli STUDI di ROMA TOR VERGATA

UNIVERSITA` degli STUDI di ROMA TOR VERGATA Carbonation of minerals and industrial residues for CO 2 storage: perspectives of application in energy generation systems 1 R. Baciocchi, 1 G. Costa, 2 M. Mazzotti, 3 A. Polettini, 3 R.Pomi, 2 V. Prigiobbe

More information

Comparison of natural radioactivity removal methods for drinking water supplies: A review

Comparison of natural radioactivity removal methods for drinking water supplies: A review Comparison of natural radioactivity removal methods for drinking water supplies: A review E. Esmeray, M. E. Aydin Selcuk University Environmental Engineering Department, Konya Turkey e-mail: eesmeray@selcuk.edu.tr

More information

Supporting Information

Supporting Information Supporting Information Wiley-VCH 2005 69451 Weinheim, Germany Magnetic Nanoparticle-Capped Mesoporous Silica Nanorod-Based Stimuli-Responsive Controlled Release Delivery System** Supratim Giri, Brian G.

More information

Chemistry at Work. How Chemistry is used in the Water Service

Chemistry at Work. How Chemistry is used in the Water Service Chemistry at Work How Chemistry is used in the Water Service WATER TREATMENT Everyday, more than 100 water treatment works in Northern Ireland put approximately 680 million litres of water into the supply

More information

Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry

Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry Why? Chemists are concerned with mass relationships in chemical reactions, usually run on a macroscopic scale (grams, kilograms, etc.). To deal with

More information

Chrysotile Asbestos in Pure Talc

Chrysotile Asbestos in Pure Talc J. Soc. Cosmet. Chem., 26, 431-437 (September 1975) Differential Thermal Analysis of Chrysotile Asbestos in Pure Talc Talc Containing Other Minerals and W. LUCKEWICZ, B.S.* Presented October 14, 1974,

More information

Chem 1A Exam 2 Review Problems

Chem 1A Exam 2 Review Problems Chem 1A Exam 2 Review Problems 1. At 0.967 atm, the height of mercury in a barometer is 0.735 m. If the mercury were replaced with water, what height of water (in meters) would be supported at this pressure?

More information

WATER CHEMISTRY AND POOL WATER BALANCE

WATER CHEMISTRY AND POOL WATER BALANCE C R6 H A PT E WATER CHEMISTRY AND POOL WATER BALANCE LEARNING OBJECTIVES After completely studying this chapter, you should be able to: Understand and list the parameters upon which water balance is based.

More information

Asbestos. a mineral habit characterized by long, thin, strong, flexible fibers equivalent to hairs or whiskers. How long?

Asbestos. a mineral habit characterized by long, thin, strong, flexible fibers equivalent to hairs or whiskers. How long? Asbestos The term asbestiform describes a mineral habit characterized by long, thin, strong, flexible fibers equivalent to hairs or whiskers How long? Definition varies Modern Uses of Asbestos Asbestos

More information

Temperature N Source and Rate CEC (less when high) Application method + H +

Temperature N Source and Rate CEC (less when high) Application method + H + Ammonia Volatilization Urease activity Air Exchange Temperature N Source and Rate CEC (less when high) Application method NH 4 NH 3 H Urea If ph and temperature can be kept low, little potential exists

More information

QUANTITATIVE DETERMINATION OF COMMON TYPES OF ASBESTOS BY DIFFUSE REFLECTANCE FTIR

QUANTITATIVE DETERMINATION OF COMMON TYPES OF ASBESTOS BY DIFFUSE REFLECTANCE FTIR MATERIALS ANALYSIS QUANTITATIVE DETERMINATION OF COMMON TYPES OF ASBESTOS BY DIFFUSE REFLECTANCE FTIR Solutions for Your Analytical Business Markets and Applications Programs Solution Note Materials Author(s)

More information

SYLLABUS. Semester: Spring 2009. Requirements: Text: General Chemistry. 9 th Edition, Chang, 2007

SYLLABUS. Semester: Spring 2009. Requirements: Text: General Chemistry. 9 th Edition, Chang, 2007 SYLLABUS Course: General Chemistry II: CHEM-1100-001 Lecture: 10:30 AM-12:00 PM Tues. & Thurs. in Room 6068 Recitation: 12:00 PM-12:50 PM in Room 3066 Laboratory: 01:00-03:50 PM Wed. in Room 3066 Semester:

More information

Chapter 1 The Atomic Nature of Matter

Chapter 1 The Atomic Nature of Matter Chapter 1 The Atomic Nature of Matter 6. Substances that cannot be decomposed into two or more simpler substances by chemical means are called a. pure substances. b. compounds. c. molecules. d. elements.

More information

BOWEN'S REACTION SERIES

BOWEN'S REACTION SERIES BOWEN'S REACTION SERIES Purpose John J. Thomas Frequently, people cannot visualize the mineral associations that form the sequences of igneous rocks that you find in the earth's crust and what happens

More information

Oil absorption in mesoporous silica particles

Oil absorption in mesoporous silica particles Processing and Application of Ceramics 4 [4] (2010) 265 269 Oil absorption in mesoporous silica particles Radislav Filipović 1,2,*, Dragica Lazić 1, Mitar Perušić 1, Ivan Stijepović 3 1 Faculty of Technology,

More information

ENE 806, Project Report 3 CHEMICAL PRECIPITATION: WATER SOFTENING. Grégoire Seyrig Wenqian Shan

ENE 806, Project Report 3 CHEMICAL PRECIPITATION: WATER SOFTENING. Grégoire Seyrig Wenqian Shan ENE 806, Project Report 3 CHEMICAL PRECIPITATION: WATER SOFTENING Grégoire Seyrig Wenqian Shan College of Engineering, Michigan State University Spring 2007 ABSTRACT The groundwater with high level initial

More information

ph is an expression of the concentration of hydrogen ions in solution

ph is an expression of the concentration of hydrogen ions in solution What is Acidity? An acid is a substance that gives off hydrogen ions ( H + ). A base is a substance that gives off hydroxyl ions. ( OH - ). ph is an expression of the concentration of hydrogen ions in

More information

Chemical Equilibrium. Rate Forward Reaction = Rate Reverse Reaction. Chapter 14. Hill, Petrucci, McCreary & Perry 4 th. Ed.

Chemical Equilibrium. Rate Forward Reaction = Rate Reverse Reaction. Chapter 14. Hill, Petrucci, McCreary & Perry 4 th. Ed. Chapter 14 Chemical Equilibrium Hill, Petrucci, McCreary & Perry 4 th Ed. Chemical Equilibrium Many Reactions seem to STOP before all the reactants are used up. The Concentrations of Reactants and Products

More information

Chapter 8 - Chemical Equations and Reactions

Chapter 8 - Chemical Equations and Reactions Chapter 8 - Chemical Equations and Reactions 8-1 Describing Chemical Reactions I. Introduction A. Reactants 1. Original substances entering into a chemical rxn B. Products 1. The resulting substances from

More information

Chemical calculations

Chemical calculations Chemical calculations Stoichiometry refers to the quantities of material which react according to a balanced chemical equation. Compounds are formed when atoms combine in fixed proportions. E.g. 2Mg +

More information

Electrochemical Kinetics ( Ref. :Bard and Faulkner, Oldham and Myland, Liebhafsky and Cairns) R f = k f * C A (2) R b = k b * C B (3)

Electrochemical Kinetics ( Ref. :Bard and Faulkner, Oldham and Myland, Liebhafsky and Cairns) R f = k f * C A (2) R b = k b * C B (3) Electrochemical Kinetics ( Ref. :Bard and Faulkner, Oldham and Myland, Liebhafsky and Cairns) 1. Background Consider the reaction given below: A B (1) If k f and k b are the rate constants of the forward

More information

Modification of Pd-H 2 and Pd-D 2 thin films processed by He-Ne laser

Modification of Pd-H 2 and Pd-D 2 thin films processed by He-Ne laser Modification of Pd-H 2 and Pd-D 2 thin films processed by He-Ne laser V.Nassisi #, G.Caretto #, A. Lorusso #, D.Manno %, L.Famà %, G.Buccolieri %, A.Buccolieri %, U.Mastromatteo* # Laboratory of Applied

More information

Physical & Chemical Properties. Properties

Physical & Chemical Properties. Properties Physical & Chemical Properties Properties Carbon black can be broadly defined as very fine particulate aggregates of carbon possessing an amorphous quasi-graphitic molecular structure. The most significant

More information

Chemical and Morphological Comparison of Erionite from Oregon, North Dakota, and Turkey

Chemical and Morphological Comparison of Erionite from Oregon, North Dakota, and Turkey Prepared for U.S. Environmental Protection Agency, Region 8 Chemical and Morphological Comparison of Erionite from Oregon, North Dakota, and Turkey By Heather A. Lowers, David T. Adams, Gregory P. Meeker,

More information

Science Standard Articulated by Grade Level Strand 5: Physical Science

Science Standard Articulated by Grade Level Strand 5: Physical Science Concept 1: Properties of Objects and Materials Classify objects and materials by their observable properties. Kindergarten Grade 1 Grade 2 Grade 3 Grade 4 PO 1. Identify the following observable properties

More information

Summary of Basalt-Seawater Interaction

Summary of Basalt-Seawater Interaction Summary of Basalt-Seawater Interaction Mg 2+ is taken up from seawater into clay minerals, chlorite, and amphiboles, in exchange for Ca 2+, which is leached from silicates into solution. K + is taken up

More information

AS B E S T O S C O N V E R S I O N P R O C E S S ( AC P )

AS B E S T O S C O N V E R S I O N P R O C E S S ( AC P ) AS B E S T O S C O N V E R S I O N P R O C E S S ( AC P ) Dipl.-Ing. F.W. Mayer, Dr. H. Kolb, Prof. Dr. A. Mayer, Dipl.-Ing. T. Pollak ARP - Analysing, Recycling, Processing GmbH and Mining University

More information

CHEM1001 Example Multiple Choice Questions

CHEM1001 Example Multiple Choice Questions HM00 xample Multiple hoice Questions The following multiple choice questions are provided to illustrate the type of questions used in this section of the paper and to provide you with extra practice. It

More information

Deposition of Magnesium Silicide Nanoparticles by the Combination of Vacuum Evaporation and Hydrogen Plasma Treatment

Deposition of Magnesium Silicide Nanoparticles by the Combination of Vacuum Evaporation and Hydrogen Plasma Treatment Proc. Int. Conf. and Summer School on Advanced Silicide Technology 2014 JJAP Conf. Proc. 3 (2015) 011301 2015 The Japan Society of Applied Physics Deposition of Magnesium Silicide Nanoparticles by the

More information

Chemical Engineering - CHEN

Chemical Engineering - CHEN Auburn University 1 Chemical Engineering - CHEN Courses CHEN 2100 PRINCIPLES OF CHEMICAL ENGINEERING (4) LEC. 3. LAB. 3. Pr. (CHEM 1110 or CHEM 1117 or CHEM 1030) and (MATH 1610 or MATH 1613 or MATH 1617

More information

NORDIC VOLCANOLOGICAL INSTITUTE 78 05 UNIVERSITY OF ICELANO XRF-SPECTROSCOPY. February '.1 9 7 0

NORDIC VOLCANOLOGICAL INSTITUTE 78 05 UNIVERSITY OF ICELANO XRF-SPECTROSCOPY. February '.1 9 7 0 NORDIC VOLCANOLOGICAL INSTITUTE 78 05 UNIVERSITY OF ICELANO THE ANALYSIS OF RUBIDIUM IN LOW POTASSIUM THOLEIITES BY XRF-SPECTROSCOPY b v February '.1 9 7 0 - 1 - INTRODUCTION The low Rb concentration of

More information

Ref. Ch. 11 in Superalloys II Ch. 8 in Khanna Ch. 14 in Tien & Caulfield

Ref. Ch. 11 in Superalloys II Ch. 8 in Khanna Ch. 14 in Tien & Caulfield MTE 585 Oxidation of Materials Part 1 Ref. Ch. 11 in Superalloys II Ch. 8 in Khanna Ch. 14 in Tien & Caulfield Introduction To illustrate the case of high temperature oxidation, we will use Ni-base superalloys.

More information

105 Adopted: 27.07.95

105 Adopted: 27.07.95 105 Adopted: 27.07.95 OECD GUIDELINE FOR THE TESTING OF CHEMICALS Adopted by the Council on 27 th July 1995 Water Solubility INTRODUCTION 1. This guideline is a revised version of the original Guideline

More information

CHEM 120 Online: Chapter 6 Sample problems Date: 2. Which of the following compounds has the largest formula mass? A) H2O B) NH3 C) CO D) BeH2

CHEM 120 Online: Chapter 6 Sample problems Date: 2. Which of the following compounds has the largest formula mass? A) H2O B) NH3 C) CO D) BeH2 CHEM 120 Online: Chapter 6 Sample problems Date: 1. To determine the formula mass of a compound you should A) add up the atomic masses of all the atoms present. B) add up the atomic masses of all the atoms

More information

TDS. Dirk Rosenthal Department of Inorganic Chemistry Fritz-Haber-Institut der MPG Faradayweg 4-6, DE 14195 Berlin dirkrose@fhi-berlin.mpg.

TDS. Dirk Rosenthal Department of Inorganic Chemistry Fritz-Haber-Institut der MPG Faradayweg 4-6, DE 14195 Berlin dirkrose@fhi-berlin.mpg. Modern Methods in Heterogeneous Catalysis Research TDS Dirk Rosenthal Department of Inorganic Chemistry Fritz-Haber-Institut der MPG Faradayweg 4-6, DE 14195 Berlin dirkrose@fhi-berlin.mpg.de TDS = TPD

More information

Chemical Kinetics. Reaction Rate: The change in the concentration of a reactant or a product with time (M/s). Reactant Products A B

Chemical Kinetics. Reaction Rate: The change in the concentration of a reactant or a product with time (M/s). Reactant Products A B Reaction Rates: Chemical Kinetics Reaction Rate: The change in the concentration of a reactant or a product with time (M/s). Reactant Products A B change in number of moles of B Average rate = change in

More information

Well Water Iron Removal Using Quantum DMI-65 Granular Filter Media

Well Water Iron Removal Using Quantum DMI-65 Granular Filter Media Well Water Iron Removal Using Quantum DMI-65 Granular Filter Media ASME Research Committee Power Plant and Environmental Chemistry Overland Park, Kansas April 2-4, 2007 Prepared by: W. H. Stroman Primary

More information

DETERMINING THE ENTHALPY OF FORMATION OF CaCO 3

DETERMINING THE ENTHALPY OF FORMATION OF CaCO 3 DETERMINING THE ENTHALPY OF FORMATION OF CaCO 3 Standard Enthalpy Change Standard Enthalpy Change for a reaction, symbolized as H 0 298, is defined as The enthalpy change when the molar quantities of reactants

More information

FILTRATION. Water Treatment Course

FILTRATION. Water Treatment Course FILTRATION Course, Zerihun Alemayehu FILTRATION Filtration involves the removal of suspended and colloidal particles from the water by passing it through a layer or bed of a porous granular material, such

More information

ISR IRON REMOVAL MEDIA. Characteristics. Recommended influent Conditions. Description

ISR IRON REMOVAL MEDIA. Characteristics. Recommended influent Conditions. Description ISR IRON REMOVAL MEDIA Description INDION ISR is a special media designed to provide excellent catalytic properties to remove dissolved iron from ground water. INDION ISR is an insoluble media which oxidizes

More information

Coal Properties, Sampling & Ash Characteristics by Rod Hatt Coal Combustion, Inc. Versailles, KY 859-873-0188

Coal Properties, Sampling & Ash Characteristics by Rod Hatt Coal Combustion, Inc. Versailles, KY 859-873-0188 Coal Properties, Sampling & Ash Characteristics by Rod Hatt Coal Combustion, Inc. Versailles, KY 859-873-0188 Introduction The Powder River Coal is classified as sub-bituminous ranked coal. Coal rank is

More information

Update of the scientific evidence on asbestos and cancer. Kurt Straif, MD MPH PhD. The IARC Monographs

Update of the scientific evidence on asbestos and cancer. Kurt Straif, MD MPH PhD. The IARC Monographs Update of the scientific evidence on asbestos and cancer Kurt Straif, MD MPH PhD International Agency for Research on Cancer Lyon, France World Health Organisation Asturias, 17 March 2011 The IARC Monographs

More information

Scanning Electron Microscopy Services for Pharmaceutical Manufacturers

Scanning Electron Microscopy Services for Pharmaceutical Manufacturers Scanning Electron Microscopy Services for Pharmaceutical Manufacturers Author: Gary Brake, Marketing Manager Date: August 1, 2013 Analytical Testing Laboratory www.atl.semtechsolutions.com Scanning Electron

More information

Chemistry Diagnostic Questions

Chemistry Diagnostic Questions Chemistry Diagnostic Questions Answer these 40 multiple choice questions and then check your answers, located at the end of this document. If you correctly answered less than 25 questions, you need to

More information

Ion Beam Sputtering: Practical Applications to Electron Microscopy

Ion Beam Sputtering: Practical Applications to Electron Microscopy Ion Beam Sputtering: Practical Applications to Electron Microscopy Applications Laboratory Report Introduction Electron microscope specimens, both scanning (SEM) and transmission (TEM), often require a

More information

1. Fluids Mechanics and Fluid Properties. 1.1 Objectives of this section. 1.2 Fluids

1. Fluids Mechanics and Fluid Properties. 1.1 Objectives of this section. 1.2 Fluids 1. Fluids Mechanics and Fluid Properties What is fluid mechanics? As its name suggests it is the branch of applied mechanics concerned with the statics and dynamics of fluids - both liquids and gases.

More information

7. 1.00 atm = 760 torr = 760 mm Hg = 101.325 kpa = 14.70 psi. = 0.446 atm. = 0.993 atm. = 107 kpa 760 torr 1 atm 760 mm Hg = 790.

7. 1.00 atm = 760 torr = 760 mm Hg = 101.325 kpa = 14.70 psi. = 0.446 atm. = 0.993 atm. = 107 kpa 760 torr 1 atm 760 mm Hg = 790. CHATER 3. The atmosphere is a homogeneous mixture (a solution) of gases.. Solids and liquids have essentially fixed volumes and are not able to be compressed easily. have volumes that depend on their conditions,

More information

Chemical Waves in the Belousov-Zhabotinsky Reaction: Determining a Rate Constant with a Ruler

Chemical Waves in the Belousov-Zhabotinsky Reaction: Determining a Rate Constant with a Ruler Chemical Waves in the Belousov-Zhabotinsky Reaction: Determining a Rate Constant with a Ruler John A. Pojman Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg,

More information

Igneous Geochemistry. What is magma? What is polymerization? Average compositions (% by weight) and liquidus temperatures of different magmas

Igneous Geochemistry. What is magma? What is polymerization? Average compositions (% by weight) and liquidus temperatures of different magmas 1 Igneous Geochemistry What is magma phases, compositions, properties Major igneous processes Making magma how and where Major-element variations Classification using a whole-rock analysis Fractional crystallization

More information

Chapter Test B. Chapter: Measurements and Calculations

Chapter Test B. Chapter: Measurements and Calculations Assessment Chapter Test B Chapter: Measurements and Calculations PART I In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question. 1.

More information

Removal of Sulfate from Waste Water by Activated Carbon. Mohammed Sadeq Salman Computer Centre/ University of Baghdad

Removal of Sulfate from Waste Water by Activated Carbon. Mohammed Sadeq Salman Computer Centre/ University of Baghdad Al-Khwarizmi Engineering Journal, Vol. 5, No. 3, PP 72-76 (29) Al-Khwarizmi Engineering Journal Removal of Sulfate from Waste Water by Activated Carbon Mohammed Sadeq Salman Computer Centre/ University

More information

Soil contamination and remediation. Introduction to soil chemistry

Soil contamination and remediation. Introduction to soil chemistry Soil contamination and remediation Introduction to soil chemistry Chemistry background History chemical reactions Colloids - soil ph soil s buffer capacity Chemistry - background atom, molecule, chem.

More information

CHAPTER 4: MATTER & ENERGY

CHAPTER 4: MATTER & ENERGY CHAPTER 4: MATTER & ENERGY Problems: 1,3,5,7,13,17,19,21,23,25,27,29,31,33,37,41,43,45,47,49,51,53,55,57,59,63,65,67,69,77,79,81,83 4.1 Physical States of Matter Matter: Anything that has mass and occupies

More information

AP Chemistry 2007 Scoring Guidelines Form B

AP Chemistry 2007 Scoring Guidelines Form B AP Chemistry 2007 Scoring Guidelines Form B The College Board: Connecting Students to College Success The College Board is a not-for-profit membership association whose mission is to connect students to

More information

rate = k [NO] 2 [H 2 ] CHEMICAL KINETICS Review Exam 3 1. How FAST {Speed like miles per hour and 2. By what MECHANISM Does a Reaction Take Place?

rate = k [NO] 2 [H 2 ] CHEMICAL KINETICS Review Exam 3 1. How FAST {Speed like miles per hour and 2. By what MECHANISM Does a Reaction Take Place? Review Chap 14: CHEMICAL KINETICS Review Exam Chapters 14 15 16 CHEMICAL KINETICS DEALS WITH 1. How FAST {Speed like miles per hour and. By what MECHANISM Does a Reaction Take Place? Given the following

More information

CHEM 116 Rates of Reaction

CHEM 116 Rates of Reaction UMass Boston, Chem 6 CHEM 6 Rates of Reaction FSG is cancelled Lecture Prof. Sevian today (Oct 4) in order to keep both FSG sections at the same pace (since there was no school yesterday) Today s agenda

More information

Unit 6 The Mole Concept

Unit 6 The Mole Concept Chemistry Form 3 Page 62 Ms. R. Buttigieg Unit 6 The Mole Concept See Chemistry for You Chapter 28 pg. 352-363 See GCSE Chemistry Chapter 5 pg. 70-79 6.1 Relative atomic mass. The relative atomic mass

More information

Test Review # 9. Chemistry R: Form TR9.13A

Test Review # 9. Chemistry R: Form TR9.13A Chemistry R: Form TR9.13A TEST 9 REVIEW Name Date Period Test Review # 9 Collision theory. In order for a reaction to occur, particles of the reactant must collide. Not all collisions cause reactions.

More information

EXPERIMENT 7 Reaction Stoichiometry and Percent Yield

EXPERIMENT 7 Reaction Stoichiometry and Percent Yield EXPERIMENT 7 Reaction Stoichiometry and Percent Yield INTRODUCTION Stoichiometry calculations are about calculating the amounts of substances that react and form in a chemical reaction. The word stoichiometry

More information