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Tetrachlorobiphenyl removal from sludge matrix using mixed crystal Ti0.97Fe0.02Ni0.01O2 thin film

Paper ID Volume ID Publish Year Pages File Format Full-Text
45446 46412 2015 7 PDF Available
Title
Tetrachlorobiphenyl removal from sludge matrix using mixed crystal Ti0.97Fe0.02Ni0.01O2 thin film
Abstract

•Ti:Fe:Ni nano-composite thin film was successfully synthesized and used as catalyst.•Tetrachlorobiphenyl was successfully removed from sludge using thin film method.•Nano-particle surface h+ and OH− groups played an important role in PCB removal.•Effect of pH on PCB decomposition and formation rates and behaviors were determined.•A model was proposed to explain further chlorination and PCB formation under UVC.

In this study, 2,2′,5,5′-tetrachlorobiphenyl removal from activated sludge matrix using thin film (TF)-based photocatalytic (PCT – TF + UVC + H2O2) and UVC + H2O2 (photolytic) treatment systems were investigated for three different initial sludge pHi values of 3.0 ± 0.1; 7.3 ± 0.1 and 10.0 ± 0.1. A novel, visible light active Ti:Fe:Ni nano composite TF was successfully synthesized and used as catalyst. The fabricated TF was characterized by SEM, TEM, XRD, XPS and UV–vis spectroscopy methods. Experimental results indicated that while raw industrial sludge contains only 2,2′,5,5′'-tetrachlorobiphenyl, treated sludge samples contained more chlorinated PCB congeners in descending chlorination order from 2,2′,3,3′,4,4′,5,5′,6,6′ decachlorobiphenyl to 2,3′,4,4′,5 pentachlorobiphenyl. Experimental results also indicated that 2,2′,5,5′-tetrachlorobiphenyl was removed from the sludge matrix by only TF-based PCT that was carried out at neutral pHi. In addition, UVC + H2O2 system caused significant PCB formation at all studied pH levels. PCB generation/degradation reactions followed pseudo-first order reaction kinetics. Obtained results also proposed that UV irradiation can induce CCl bond cleavage in chlorinated compounds yielding Cl radicals, responsible for further chlorination. The kobs value observed in 2,2′,5,5′-tetrachlorobiphenyl degradation by TF-based PCT at pHi = 7.3 ± 0.1 was 0.0169 ± 10−3 min−1 and 1.5 times higher than at pHi = 3.0 ± 0.1. The observed kobs values in TF based PCT for PCB generation at pHi = 3.0 ± 0.1 and pHi = 10.0 ± 0.1 were 0.0037 ± 10−3 and 0.0015 ± 10−3 min−1, respectively.

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Keywords
DS, dry solids; MLSS, mixed liquor suspended solids; MLVSS, mixed liquor volatile suspended solids; PCB(s), polychlorinated biphenyls; POPs, persistent organic pollutants; pH, iinitial pH value; PCT, photocatalytic treatment; SEM, scanning electron micros
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Tetrachlorobiphenyl removal from sludge matrix using mixed crystal Ti0.97Fe0.02Ni0.01O2 thin film
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 179, December 2015, Pages 171–177
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us