A Photocatalytic Rotating Disc Reactor with TiO₂ Nanowire Arrays Deposited for Industrial Wastewater Treatment.

Fang Li,Jiantao Li,Wai Szeto,Haibao Huang,Dennis Leung

doi:10.3390/molecules22020337

Abstract

A photocatalytic rotating disc reactor (PRD-reactor) with TiO2 nanowire arrays deposited on a thin Ti plate is fabricated and tested for industrial wastewater treatment. Results indicate that the PRD-reactor shows excellent decolorization capability when tested with methyl orange (>97.5%). Advanced oxidation processes (AOP), including photocatalytic oxidation and photolytic reaction, occurred during the processing. Efficiency of the AOP increases with reduction in light absorption pathlength, which enhanced the photocatalytic reaction, as well as by increasing oxygen exposure of the wastewater thin film due to the rotating disc design. It is found that, with a small dosage of hydrogen peroxide, the mineralization efficiency of industrial biodegraded wastewater can be enhanced, with a superior mineralization of >75% total organic carbon (TOC) removal. This is due to the fact that the TiO2 photocatalysis and hydrogen peroxide processes generate powerful oxidants (hydroxyl radicals) that can strongly improve photocatalytic oxidation efficiency. Application of this industrial wastewater treatment system is benefited from the TiO2 nanowire arrays, which can be fabricated by a mild solvothermal method at 80 °C and under atmospheric pressure. Similar morphologies and microstructures are found for the TiO2 nanowire arrays deposited on a large metal Ti disc, which makes the wastewater treatment process more practical and economical.

Highlights

Since the first research paper from Fujishima and Honda regarding photocatalytic water splitting on an anatase TiO2 electrode was reported [1], substantial research work has been conducted, showing that nanostructured TiO2 is an effective material for photocatalytic wastewater treatment [2]
The present study shows that rotating film disc design can solve the above-mentioned problems
The transmission electron microscopy (TEM) images of the scraped fractals of TiO2 nanowire deposited on the Ti plate (Figure 1a) clearly show that the as-prepared samples still contain a TiO2 nanowire array structure

Summary

Introduction

Since the first research paper from Fujishima and Honda regarding photocatalytic water splitting on an anatase TiO2 electrode was reported [1], substantial research work has been conducted, showing that nanostructured TiO2 is an effective material for photocatalytic wastewater treatment [2]. This is mainly because TiO2 has several remarkable physicochemical properties, such as photocatalytic activity, chemical stability, nontoxicity, and low cost. Some inevitable problems, such as recyclability and secondary pollution, exist for TiO2 in a suspended powder form. TiO2 thin film photocatalyst can address these problems well. Use of titanium plates as Ti source to prepare TiO2 nanostructure film material is a promising preparation method, and, in this regard, highly ordered TiO2 nanotube arrays prepared by anodization have been reported [7,8,9,10]; they require a massive electrical

Results

Discussion

Conclusion