Dinamica degli inquinanti Characterization techniques Renato Baciocchi University of Rome Tor Vergata, Rome, Italy
Characterization techniques Preparation Water content Loss on Ignition, LOI Alkaline extraction technique: elemental composition Atomic Absorption Spectroscopy, AAS: elemental composition X-Ray Diffraction, XRD: crystalline phases detection Thermo Gravimetric Analysis, TGA/DTA Raman Spectroscopy Results (MSWI BA/APC Steel Slags)
Preparation Quartering procedure Removal of visually oversized particles Size classification (ASTM sieves) Several granulometric classes obtained
Water content Performed in 3-replicates on each granulometric class A 25 g sample is dried at 60 C (at least 24 h) Cooling down (10 min) in a dessiccator w = Mtot w, sample water content M totw, weight of the wet sample + container M totd, weight of the dry sample + container t, container weight M campw, wet sample weight t M campd, dry sample weight M w, weight of water in the sample w Mtot d Mtot d Mw 100 = 100 Mcamp d
Loss on Ignition (LOI) Provides an estimate of the content of: -graviticwater - chemically bound water (crystalline/hydroxide) -CO 2, SO 2 and other pyrolitic volatile compounds - organic matter A 1 g sample is put in a muffle oven (30 min at 400 C + 20 min at 1000 C) After cooling down sample stored in a dessiccator and weight LOI = Mtot Mtot 100 LOI, Loss on ignition M toti, weight of the original sample + container M totf, weight of the sample after treatment + container i Mcamp i f
Alkaline extraction Allows the quantitative extraction of elements into the aqueous phase 0.5 g sample are placed in a Pt-crucible and mixed with 3.0 g LiB 4 0.5 g LiB 4 is finally added to reduce the fusion temperature of the solid Samples are put in a muffle oven at 1050 C for 2 hours After cooling the crucible is placed in a 2L beaker 10% HNO3 solution is added to the beaker so to cover the sample The system is kept under moderate mixing at 60 C untill the solid is dissolved completely (about 12 hours) The obtained solution is filtered and the solution mixed with nitric acid used to wash the beaker (total volume 200ml) The solution is then analyzed by AAS The procedure is usually repeated in triplicate for each sample
Chlorides content The Italian Standard Procedure UNI 8520/IRSA is followed A 5 g sample is mixed with 200 ml distilled water and brought to boiling point The system is kept under mixing for 2 hours (slightly below the boiling point) The system is then decanted for 10 min and the solution filtered The solution is diluted before titration, depending on the expected concentration (1:2-1:10 dilution can be used) and a drop of indicator (K 2 CrO 4 ) is added. Titration is made adding a volume of a 0,1 N AgNO 3 solution until colour change is observed, thus provinding the equivalents of chloride V N V N = AgNO 3 AgNO 3 = Cl Cl n equvalenti
Sulphates content The Italian Standard Procedure UNI 8520/IRSA are followed A 5 g sample is mixed with 150 ml distilled water and brought to boiling point After 30 min, 30 ml 18% HCl solution are added and left boiling for 10 min Glycerine solution (1:1 in water), NaCl solution( 50 g in 250 ml water/10 ml HCl) are prepared and then mixed (1:2 volume ratio) BaCl 2 solution (22.5g hydrated salt in 250 ml water) is prepared Mix and stir: 30 ml sample + 10 ml Gly/NaCl solution + 5 ml BaCl 2 solution A BaSO 4 solution is formed and stabilized by NaCl/Gly Settle for 15 min then stir for 15s and pour the solution immediately into the AAS vial (precipitation must be avoided) An AAS calibration curve with sodium sulphate is previously prepared
Carbonates content The CO 2 evolved by reaction of carbonates with HCl is measured Ambient P and T are measured The sample weight to be used is given by a proper table. The sample is added to bottle A 10 ml HCl (37%) is also added to bottle A The CO 2 volume evolved is measured on the graduated tube B The carbonate content is readily calculated
X-Ray Diffraction (XRD) The XRD technique is based on the Bragg law
TGA
Characterization of alkaline residues Materials Bottom Ash (BA) from a Municipal Solid Waste Incinerator (MSWI) (Rome, I) Slags from a Stainless Steel Industry (Mix from landfill) (Italy) Air Pollution Control (APC) residues from a medical waste incinerator (Rome, I)
MSWI BA characterization Particle size distribution Weight %
MSWI BA characterization Size classification Name Particle Size Weight fraction(%) Oversize >12 mm 4,74 CLASS A 5,6<d<12 mm 27,60 CLASS B 2<d<5,6 mm 34,63 CLASS C 0,425<d<2 mm 26,98 CLASS D 0,150<d<0,425 mm 4,96 CLASS E d<0,150 mm 0,87
MSWI BA characterization Elemental composition: macro-elements Concentrazione (%) 40 30 20 10 0 Ca Al Fe Mg Na K
MSWI BA characterization Elemental composition: micro-elements Concentrazione (mg/kg) 10.00 1.00 0.10 0.01 Mo Cu Zn Pb Cr Mn Ni Sb V
MSWI BA characterization 600 XRD Class D 500 Relative intensity (%) 400 300 200 Class D Calcium hydroxide 100 0 5 15 25 35 45 55 65 75 85 2 theta
MSWI BA characterization 600 XRD Class D 500 Relative intensity (%) 400 300 200 Class D Hydrocalumite 100 0 5 15 25 35 45 55 65 75 85 2 theta
MSWI BA characterization 700 XRD Class D 600 500 Relative intensity (%) 400 300 200 Class D Calcite 100 0 5 15 25 35 45 55 65 75 85 2 theta
MSWI BA characterization 600 XRD Class D 500 Relative intensity (%) 400 300 200 Class D Forsterite 100 0 5 15 25 35 45 55 65 75 85 2 theta
MSWI BA characterization 600 XRD Class D 500 Relative intensity (%) 400 300 200 Class D Calcium silicate 100 0 5 15 25 35 45 55 65 75 85 2 theta
MSWI BA characterization XRD Class D 600 500 400 Relative intensity (%) 300 200 Class D Ghelenite 100 0 5 15 25 35 45 55 65 75 85 2 theta
MSWI BA characterization XRD Class D Relative Intensity (%) 700 600 500 400 300 Classe D Hydrocalumite Calcium Hydroxide Forsterite Calcite Ghelenite Calcium silicate Quartz Hematite Calcium silicate 2 Silicato di calcio 2 Anorthoclasium 200 100 0 5 15 25 35 45 55 65 75 85 2 Theta ( )
MSWI BA characterization XRD Class A CLASSE A (5,6<d<12 mm) Relative Intensity (%) 1000 900 800 700 600 500 400 300 Classe A Hydrocalumite Calcium hydroxide Quartz Calcite Calcium silicate Ghelenite Forsterite Hematite Anorthyte Calcium silicate 2 200 100 0 5 15 25 35 45 55 65 75 85 2 Theta ( )
MSWI BA characterization XRD ghelenite MAIN PHASES Large size fractions (A-C) - Ghelenite Intensità Ca(OH) 2 Ca(OH) 2 ghelenite - Silicates A Smaller size fractions (D-E) - Hydrocalumite - Calcite - Ca(OH) 2 (products of hydration and carbonation) 5 15 25 35 45 55 65 75 85 2 Theta ( ) Hydrocalumite Calcite B C D E
MSWI BA characterization Raman Class D zona chiara zona nera Intensity (arb. units) Intensity (arb. units) 200 400 600 800 1000 Raman shift (cm -1 ) 500 1000 1500 2000 2500 3000 Raman shift (cm -1 ) zona rossa Intensity (arb. units) 250 500 750 1000 1250 Raman shift (cm -1 ) 500 1000 1500 2000 2500 3000 Raman shift (cm -1 )
MSWI BA characterization Raman Class D (view b) a Intensity (arb. units) b Amorphous C (1500 cm -1 ) Calcite (inset a) Ghelenite (inset b) Olivine (inset c) Intensity (arb. units) 200 400 Raman 600 shift (cm 800-1 ) 1000 200 400 600 800 1000 1200 1400 Raman shift (cm -1 ) c 800 850 900 950 Raman shift (cm -1 ) 500 1000 1500 2000 2500 3000 Raman shift (cm -1 )
MSWI BA characterization Raman Class A (view b) a Intensity (arb. units) b Amorphous C (1500 cm -1 ) Calcite (inset a) Ghelenite (inset b) Olivine (inset c) Intensity (arb. units) 200 400 Raman 600 shift (cm 800-1 ) 1000 200 400 600 800 1000 1200 1400 Raman shift (cm -1 ) c 800 850 900 950 Raman shift (cm -1 ) 500 1000 1500 2000 2500 3000 Raman shift (cm -1 )
Stainless Steel Slags characterization Size classification 50 A Weight fraction (%) 40 30 20 10 D C B 0 d<105 105<d<177 177<d<425 425<d<2000 Particle size (micron)
Stainless Steel Slags characterization Elemental composition: macro-elements % 60,00 50,00 40,00 30,00 20,00 10,00 0,00 Classe D tal quale Classe C tal quale Classe B tal quale Classe A tal quale Al Ca Cr Fe Mg Mn
Stainless Steel Slags characterization Elemental composition: micro-elements 0,25 0,2 0,15 Classe D tal quale Classe C tal quale Classe B tal quale Classe A tal quale % 0,1 0,05 0 As Cd Cu K Mo Na Ni Pb Sb V Zn
Stainless Steel Slags characterization XRD Ca,Al,FeO CaCO 3 Classe D Classe C Classe B Classe A Arb. Units Ca 2 (SiO) 4 MgO 5 15 25 35 45 55 65 75 85 2theta
Stainless Steel Slags characterization XRD Legend Mineral Formula a Calcium silicate Ca 2 (SiO 4 ) b Forsterite Mg 2 (SiO 4 ) c Periclasium MgO d Quartz SiO 2 e Anorthite Ca(Al 2 Si 2 O 8 ) f Ca,Al, Fe oxide Ca 12 Al 113,8 Fe 0,14 O 32 g Cr, Mg oxide MgCr 2 O 4 h Cristobalite SiO 2 j Calcium carbonate CaCO 3 k Gehlenite Ca 2 Al 2 SiO 7 n Calcium silicate Ca 2 (SiO 4 ) o Akermanite Ca 2 Mg(Si 2 O 7 ) p Cuspidine Ca 4 Si 2 O 7 (F,OH) 2 q Magnetite Fe 3 O 4 r Merwinite Ca 3 Mg(SiO 4 )
MSWI APC characterization Elemental composition and anion content Concentration (mg/kg) 1000000 100000 10000 1000 100 10 1 ~ 35% Al Ca Fe K Mg Na Si Cd Cr Cu Mn Ni Pb Zn Cl SO4 calcium speciation Content (%w/w) 50 40 30 20 10 0 ~ 75% Ca(OH)2 CaCl(OH) CaCO3 CaSO4 from TG analysis, CaCl(OH) content and calcimetry from Cl - content, leaching results and XRD analysis from calcimetry and TG analysis from SO4 2- content
MSWI APC characterization XRD
MSWI APC characterization TGA / Gas analysis CaCO 3 Ca(OH) 2 CO 2 evolved