Photodegradation of Molasses Wastewater Using TiO2-ZnO Nanohybrid Photocatalyst Supported on Activated Carbon

Journal article

Authors / Editors

Ochieng, Aoyi

Research Areas

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Publication Details

Author list: Benton O, Apollo S, Naidoo B, Ochieng A

Publisher: Taylor and Francis Group

Place: PHILADELPHIA

Publication year: 2016

Journal: Chemical Engineering Communications (0098-6445)

Journal acronym: CHEM ENG COMMUN

Volume number: 203

Issue number: 11

Start page: 1443

End page: 1454

Number of pages: 12

ISSN: 0098-6445

eISSN: 1563-5201

Languages: English-Great Britain (EN-GB)

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Abstract

Molasses wastewater (MWW) is characterized by high organic loading and a recalcitrant dark brown color. A study was carried out to determine the photocatalytic efficiency of TiO2-ZnO nanohybrid supported onto activated carbon (AC) for the remediation of MWW. Immobilization of ZnO onto TiO2 formed TiO2-ZnO, which was then supported onto AC forming TiO2-ZnO-AC composite. X-ray diffraction (XRD), scanning electron (SEM), energy-dispersive X-ray (EDX) and Fourier transform infrared (FTIR) spectroscopies, and transmission electron (TEM) microscopy revealed the successful hybridization of TiO2 and ZnO, and the subsequent support of the hybrid onto AC. Photoluminescence (PL) spectroscopy further revealed a restrained electron-hole pair recombination resulting from both the successful formation of a heterojunction, and the introduction of electron accepting AC support. Photodegradation process was monitored by color and total organic carbon (TOC) reductions. It was observed that TiO2-ZnO (ratio 3:1) supported onto AC (30% loading) had a higher adsorptive capacity and catalytic activity than bare TiO2-ZnO resulting in a 14% increment in overall color reduction. UV-photodegradation was found to be very effective for color as compared to TOC reduction, with 96% and 9% reductions, respectively, after 1 hour of irradiation. A pH of 5 was found to be optimum for photodegradation.

Keywords

Activated carbon, Color reduction, Hybrid, Immobilization, TOC reduction, UV-photodegradation

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