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

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Tarih

2015

Dergi Başlığı

Dergi ISSN

Cilt Başlığı

Yayıncı

Elsevier Science Bv

Erişim Hakkı

info:eu-repo/semantics/closedAccess

Özet

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 pH(i) 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 pH(i). 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 C-Cl bond cleavage in chlorinated compounds yielding Cl-center dot radicals, responsible for further chlorination. The k(obs) value observed in 2,2',5,5'-tetrachlorobiphenyl degradation by TF-based PCT at pH(i) = 7.3 +/- 0.1 was 0.0169 +/- 10(-3) min(-1) and 1.5 times higher than at pH(i)=3.0 +/- 0.1. The observed k(obs) values in TF based PCT for PCB generation at pH(i)=3.0 +/- 0.1 and pH(i)=10.0 +/- 0.1 were 0.0037 +/- 10(-3) and 0.0015 +/- 10(-3) min(-1), respectively. (C) 2015 Elsevier B.V. All rights reserved.

Açıklama

Anahtar Kelimeler

Tetrachlorobiphenyl, Industrial sludge, Thin film, Photocatalytic treatment, Chlorination, PCBs, Photocatalytic Activity, Tio2, Degradation, Temperature, Pcbs, Metal, Dechlorination, Deposition, Oxidation, Biphenyl

Kaynak

Applied Catalysis B-Environmental

WoS Q Değeri

Q1

Scopus Q Değeri

Q1

Cilt

179

Sayı

Künye