Decolorization of textile dyes by TiO2 -based photocatalyst using polyol as electron donor

Hao Minh Hoang,Thuy Thi Thanh Nguyen,Van Thi Bich Pham,Xuan Thi Hong Cao

doi:10.32508/stdjns.v2i5.782

Abstract

Decolorization of textile dyes including 2,6-dichlorophenolindophenol (DCIP), congo red (CR) and methyl orange (MO) by using TiO2-based photocatalyst in the presence of polyols such as glycerol and ethylene glycol was investigated. Polyols were used as sacrificial electron donors (SEDs). The results showed that the polyols improved the rate and yield of a light-induced decolorization of dyes in comparison with a photocatalytic reaction without polyols. A possible reaction mechanism of dye decolorization by the photocatalyst in the presence of electron donors was proposed. TiO2 photocatalyst absorbed light to generate electrons (e-) and holes (h+). The electrons and holes were prevented from recombining by the presence of SEDs. The free electrons and holes then involved in decolorization processes through reduction or oxidation reactions. The effects of TiO2 catalyst amounts, irradiation time and polyol concentrations on dye decolorization were investigated. The decolorization efficiency significantly increased with the increasing irradiation time, SED concentrations and certain amounts of TiO2.

Highlights

Photocatalyst causes an increase in the rate of a light-induced reaction by a catalyst
The results showed that the positions of the maximum absorption peaks of DCIP, congo red (CR) and methyl orange (MO) were 600, 498 and 464 nm, respectively
The irradiation time on DCIP solutions was 45 min while CR and MO solutions were irradiated for 90 min

Summary

Introduction

Photocatalyst causes an increase in the rate of a light-induced reaction by a catalyst. Pham Thi Bich Van, Hoang Minh Hao, Nguyen Thi Thanh Thuy, Cao Thi Hong Xuan1 – 1Nong Lam University – Ho Chi Minh City, 2HCMC University of Technology and Education photochemical system into which the energy enters via the absorption of light with a certain wavelength by one of the components such as colored organic dyes or photocatalyst [1, 7]. These systems generally consist of a semiconductor and a colored dye that adsorbs on the surface of the semiconductor. The photogenerated electron from CB decolorized R into reductive products via a chemical reduction (eq 4) [1, 11]

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Results

Conclusion