Solar-Powered Photocatalytic Fiber-Optic Cable Reactor for Waste Stream Remediation

Environmental Engineering Science, W. M. Keck Laboratories, California Institute of Technology, Pasadena, CA 91125 The design and testing of a solar-powered fiber-optic cable reactor prototype for the photocatalytic destruction of organic pollutants is presented. A concentrating collector directs sunlight into a fiber-optic cable which transmits light to a Ti02 photocatalyst immobilized on the fibers and immersed in a reaction solution. The peiformance of the reactor using solar and artificial UV radiation are compared. The system is also compared to another fiber-optic cable reactor having a 50 percent higher P.ho.toc~talytic surface area-to-reactor volume ratio to investigate niass transport llmltatrons. Reaction rates for the oxidation of 4-chlorophenol of 25 and 12 μMmin -J were measured for solar and artificial UV sources, respectively. The faster reaction rate using solar radiation is due to a higher UV light flux compared to the artificial source. Both fiber-optic reactor systems were determined not to be mass transport limited. Relative quantum efficiencies of = 0.014 and <P = 0.020 were determined for the solar and artificial irradiations, respectively. Jn agreement with previous findings, enhanced quantum efficiencies are attributed to a lower absorbed light intensity-to-photocatalytic suiface area ratio. The solar reactor prototype was found to degrade effectively 4-chlorophenol and may prove useful for the in situ passive decontamination of subsurface and other remote environments.