HETEROGENEOUS ELECTROPHOTOCATALYSIS ON NANOSTRUCTURED TiO 2 FOR REFRACTORY POLLUTANTS AND RESISTANT PATHOGENS REMOVAL FROM WATER AND WASTEWATER

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1 DIIAR - Environmental Engineering Section HETEROGENEOUS ELECTROPHOTOCATALYSIS ON NANOSTRUCTURED TiO 2 FOR REFRACTORY POLLUTANTS AND RESISTANT PATHOGENS REMOVAL FROM WATER AND WASTEWATER SIDISA Summer School 25 june 2012 PhD advisor MANUELA ANTONELLI

POLLUTANTS AND RESISTANT PATHOGENS REMOVAL FROM WATER AND

2 INDEX

3 PROCESS FUNDAMENTALS: TiO 2 PHOTOCATALYSIS ADVANCED OXIDATION PROCESS (AOP) SEMICONDUCTOR BAND GAP: 3.2 EV UV RADIATION (λ<380 NM) REACTIVE OXYGEN SPECIES (ROS) HYDROXYL RADICAL (OH ) SUPEROXIDE RADICAL (O 2 - ) DEGRADATION OF POLLUTANTS INTO LOWER MOLECULAR WEIGHT INTERMEDIATES AND MICRORGANISMS STRUCTURE DAMAGING ELECTRON-HOLE PAIRS RECOMBINATION: MAIN PROCESS DRAWBACK

2 EV UV RADIATION (λ<380 NM) REACTIVE OXYGEN SPECIES (ROS) HYDROXYL RADICAL (OH ) SUPEROXIDE

PROCESS FUNDAMENTALS: ELECTROPHOTOCATALYSIS ON NANO TiO 2 THE PROCESS INTEGRATES PHOTOCATALYTIC DEGRADATION ON NANOTUBULAR TiO 2 AND ELECTROCHEMICAL POLARIZATION TiO 2 PHOTOCATALYSIS hν CB VB e - h +

4 PROCESS FUNDAMENTALS: ELECTROPHOTOCATALYSIS ON NANO TiO 2 THE PROCESS INTEGRATES PHOTOCATALYTIC DEGRADATION ON NANOTUBULAR TiO 2 AND ELECTROCHEMICAL POLARIZATION TiO 2 PHOTOCATALYSIS hν CB VB e - h + O 2 O - 2 OH OH - CATALYST POLARIZATION NO OXIDANTS ARE REQUIRED TO GENERATE RADICALS THE CATALYST IS NOT A DISPERSED POWDER BUT IT IS DIRECTLY GROWN ON Ti SUPPORT (WIRE MESH) BY ANODIC OXIDATION A LIGHT POLARIZATION IS APPLIED TO THE TiO 2 /Ti PHOTOANODE TO MINIMISE THE RECOMBINATION OF ELECTRON/HOLE PAIRS DISSOLVED OXYGEN IS REQUIRED NANOTUBULAR SELF-ORGANIZED TiO 2 /Ti

RADICALS THE CATALYST IS NOT A DISPERSED POWDER BUT IT IS DIRECTLY GROWN ON Ti SUPPORT (WIRE MESH) BY ANODIC OXIDATION A LIGHT POLARIZATION IS

AIM OF THE PROJECT AND RESEARCH PLAN PROCESS OPTIMIZATION: PHOTOELECTROCHEMICAL ASSESSMENT CFD SIMULATIONS REACTOR DESIGN LIFE CYCLE ANALYSIS OPTIMIZATION AND DEVELOPMENTS MECHANISTIC PHENOMENA

5 AIM OF THE PROJECT AND RESEARCH PLAN PROCESS OPTIMIZATION: PHOTOELECTROCHEMICAL ASSESSMENT CFD SIMULATIONS REACTOR DESIGN LIFE CYCLE ANALYSIS OPTIMIZATION AND DEVELOPMENTS MECHANISTIC PHENOMENA INSIGHT IRRADIATION PHENOMENA TiO 2 /Ti PHOTOACTIVATION RADICAL SPECIES GENERATION ADSORPTION AND DEGRADATION KINETICS APPLICATION TO WATER AND WASTEWATER TREATMENT ORGANICS REMOVAL BY-PRODUCTS AND ECOTOXICITY ADVANCED DISINFECTION (RESISTANT PATHOGENS) BENCHMARK TESTS (O 3, H 2 O 2 /UV)

PHOTOACTIVATION RADICAL SPECIES GENERATION ADSORPTION AND DEGRADATION KINETICS APPLICATION TO WATER AND WASTEWATER

6 MECHANISTIC PHENOMENA INSIGHT: RADICAL SPECIES MEASUREMENTS SHORT LIFETIMES: 10-9 SECONDS LOW CONCENTRATIONS: MOL/L HIGH REACTIVITY: 2.80 V DIFFICULT DIRECT MEASUREMENT PROBE MOLECULES SPECIFIC CHEMICALS THAT REACT SELECTIVELY WITH REACTIVE OXYGEN SPECIES GENERATING PRODUCTS THAT CAN BE MEASURED SUPEROXIDE (O 2 - ) DETECTOR (SPECTROMETRIC METHOD): XTT QUENCHER: SUPEROXIDE DISMUTASE (SOD)

80 V DIFFICULT DIRECT MEASUREMENT PROBE MOLECULES SPECIFIC CHEMICALS THAT REACT SELECTIVELY WITH

7 Current intensity [ma] OPTIMIZATION AND DEVELOPMENTS: PHOTOELECTROCHEMICAL TESTS EXPERIMENTAL SETUP ALLOWS GENERATED PHOTOCURRENT MONITORING: TiO 2 /Ti PHOTOACTIVATION INDEX GENERATED PHOTOCURRENT = TOTAL CURRENT INDUCED CURRENT HIGHER VALUES OF PHOTOCURRENT = BETTER CATALYST PHOTOACTIVATION GENERATED PHOTOCURRENT + INDUCED CURRENT INDUCED CURRENT 0 00:00:00 00:28:48 00:57:36 01:26:24 01:55:12 02:24:00 02:52:48 Time OPERATING PARAMETERS INFLUENCE ASSESSMENT: PROCESS OPTIMIZATION

OF PHOTOCURRENT = BETTER CATALYST PHOTOACTIVATION 300 250 200 150 GENERATED PHOTOCURRENT + INDUCED CURRENT 100 50 INDUCED

8 OPTIMIZATION AND DEVELOPMENTS: CFD SIMULATIONS NON-IDEAL REACTOR HYDRAULIC BEHAVIOR NON-OPTIMIZED PROCESS YIELDS COMPUTATIONAL FLUID DYNAMIC FOR MODELING AND SIMULATION (FINITE ELEMENT SOFTWARE)

APPLICATION TO WATER AND WASTEWATER TREATMENT: ORGANICS REMOVAL AND ECOTOXICITY WATER AND WASTEWATER CHARACTERISTICS: OPTICAL PROPERTIES (TRANSMITTANCE, SUSPENDED SOLIDS)

9 APPLICATION TO WATER AND WASTEWATER TREATMENT: ORGANICS REMOVAL AND ECOTOXICITY WATER AND WASTEWATER CHARACTERISTICS: OPTICAL PROPERTIES (TRANSMITTANCE, SUSPENDED SOLIDS) CATALYST POISONING OR COVERING COMPOUNDS (OILS, METALS) TARGET POLLUTANTS REMOVAL VS. OXIDATION BY-PRODUCTS BIOLOGICAL AGGREGATE INDECES (MICRO-BIOASSAYS) VIBRIO FISCHERI DAPHNIA MAGNA

CATALYST POISONING OR COVERING COMPOUNDS (OILS, METALS) TARGET POLLUTANTS REMOVAL VS.

10 DIIAR - Environmental Engineering Section HETEROGENEOUS ELECTROPHOTOCATALYSIS ON NANOSTRUCTURED TiO 2 FOR REFRACTORY POLLUTANTS AND RESISTANT PATHOGENS REMOVAL FROM WATER AND WASTEWATER THANK YOU SIDISA Summer School 25 june 2012 andrea.turolla@mail.polimi.it

Photoelectrocatalytic Treatment and By-Product Formantion

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