Chemical and Physical Characterization of a TiO₂-Coated Fiber Optic Cable Reactor

Practical application of metal oxide photocatalysts for the remediation of contaminated wastestreams often requires immobilization of the photocatalyst in a fixed-bed reactor configuration that allows the continu ous use of the photocatalyst by eliminating the need for post-process filtration. A novel optical fiber cable reactor (OFR) is used to transmit UV light to solid-supported TiO 2 in order to investigate the photocatalytic degradation of pentachlorophenol (PCP), 4-chlorophenol (4-CP), dichloroacetate (DCA), and oxalate (OX). The distribution of light as a function of fiber diameter and the quantum efficiencies as a function of incident light intensity are investigated. Light propagation down individual fibers is found to increase with increasing fiber diameter. An increased linear transmission of light results in increased quantum efficiencies, while a 2-order of magnitude reduction in incident light intensity results in a 4-fold increase (φ = 0.010−0.042) in quantum efficiency for the degradation of 4-chlorophenol. The rates of degradation of dichloroacetate and oxalate have strong pH de pendencies. Relatively high apparent quantum efficien cies of φ = 0.010, 0.015, 0.08, and 0.17 for PCP, 4-CP, DCA, and OX, respectively, and complete mineralization to CO 2, H 2 O, and HCl are observed in the OFR system.