Ferrioxalate-mediated photodegradation of organic pollutants in contaminated water

The UV-visible photolysis of ferrioxalate in the presence of hydrogen peroxide (the UV-vis/ferrioxalate/H2O2 process) is investigated for the treatment of contaminated groundwater and industrial wastewater. This process generates the hydroxyl radical, which is a strong oxidant and reacts rapidly with most organic compounds present in solution. Tap water spiked with various organic pollutants, a process water containing chlorobenzene, a tank-bottom water containing a mixture of benzene, toluene and xylenes (BTX), a wastewater containing 1,4-dioxane and another wastewater containing methanol, formaldehyde and formic acid were treated with the UV-vis/ferrioxalate/H2O2 process and the efficiency compared with alternative oxidation processes, including the UV/H2O2 and UV-vis/Fe(II)/H2O2 (UV-Fenton) processes. The destruction of specific compounds and group parameters, such as TOC and BOD, were used to examine the relative energy efficiencies of the alternative processes. The data indicate that in nearly all cases, the new UV-vis/ferrioxalate/H2O2 process has a much higher efficiency (by a factor of about 3 to 30) than does either the UV-vis/Fe(II)/H2O2 process or the UV/H2O2 process. It is concluded that this new process is very efficient and useful for the treatment of moderate to highly contaminated waters.