Enhanced Removal of Trichloroethylene in Water Using Nano-ZnO/Polybutadiene Rubber Composites

Dae Jang,Jong Kim,Chang Ahn,Jin Joo,June Choi

doi:10.3390/catal6100152

Abstract

An innovative nanoscale ZnO/polybutadiene rubber composite (ZBRC) was developed as a valid alternative to TiO2 particles or immobilized TiO2 for the mineralization of chlorinated hydrocarbons without difficulties in the recovery of nanoscale photocatalyst particles. A synergistic increase in the removal of 1,1,2-trichloroethylene (TCE) through the coupled reaction processes (i.e., sorption, photolysis, and photocatalysis) was observed because sorption of TCE to the ultraviolet(UV)-transparent polybutadiene rubber occurred, and was coupled with the heterogeneous photocatalytic reactions with nanoscale ZnO particles on the surface of ZBRC. The removal rate of TCE decreased with an increase in the initial concentration of TCE because of both inhibited generation of electron–hole pairs and deficiency of photons to activate ZnO particles. Also, the TCE removal rate increased as the loading amount of ZBRC increased. Based on satisfactory linear regressions (R2 ≥ 0.94) between the apparent degradation rate constant (Kapp) and the initial concentration vs. the ZBRC loading amount, the Kapp values can be estimated, a priori, without performing photocatalytic experiments. The removal efficiencies were more significantly affected by the changes in the initial concentration of TCE and the ZBRC loading amounts than by the changes in light intensity and pH in aqueous solutions. From the results of response surface analysis, the greater removal efficiencies of TCE were achieved with higher pH values, greater amounts of ZBRC, and greater intensity of light. Based on these results, newly-developed ZBRC with both high removal efficiency and low cost performs as a valid alternative to TiO2 particles or immobilized TiO2 for the mineralization of chlorinated hydrocarbons in various environmental and industrial matrices.

Highlights

In the last three decades, heterogeneous photocatalytic oxidation processes with TiO2 -based materials and binary oxides have been investigated for the remediation of water resources contaminated by recalcitrant hydrocarbons [1,2,3,4,5,6,7,8,9,10,11]
While many TiO2 -based photocatalysts have been developed with bare TiO2 or modified TiO2 particles, several limitations have still been reported for bare TiO2 or modified TiO2 particles [7,8]
These results indicate that the initiation of the zinc oxide (ZnO) photocatalysis reaction is not significantly affected by the light intensity as long as a sufficient amount of photon energy

Summary

Introduction

In the last three decades, heterogeneous photocatalytic oxidation processes with TiO2 -based materials and binary oxides have been investigated for the remediation of water resources contaminated by recalcitrant hydrocarbons [1,2,3,4,5,6,7,8,9,10,11]. These studies have reported that highly reactive transitory species (e.g., superoxide radical (O2 ·− ), hydroxyl radicals (·OH), and hydrogen peroxide (H2 O2 )) involved in the heterogeneous photocatalytic reactions effectively degrade various ambiguous. TiO2 photocatalytic membrane reactors have been recently developed by integrating hybrid photocatalysis-membrane processes for the complete recovery of photocatalyst particles [12,13]

Objectives

Methods

Conclusion