| Abstract
| - The degradation of pentachlorophenol (PCP) in a heterogeneous system with maghemite (γ-Fe2O3) and oxalate under UV illumination was investigated in this study. The results of adsorption experiments demonstrated competitive adsorption between PCP and oxalic acid on the surface of γ-Fe2O3. The results of photodegradation experiments showed that the rate of PCP degradation strongly relied on the oxalic acid concentration and that an optimal tested initial concentration of oxalic acid (C0ox) of 0.8 mM was obtained under our experimental conditions. It was observed that a sufficient amount of oxalic acid can be adsorbed on the γ-Fe2O3 to form various Fe(III)-oxalate complexes at C0ox = 0.8 mM. During the photoreaction, Fe(C2O4)2− and Fe(C2O4)33− were found to be the dominant Fe(III)-oxalate complexes at different C0ox, while Fe(C2O4)22− was the dominant Fe(II)-oxalate complex at C0ox ≥ 0.8 mM. The mechanism of H2O2 formation and consumption in the UV-irradiated γ-Fe2O3/oxalate system was proposed and evaluated. Furthermore, six intermediates of PCP degradation were identified by GC/MS, HPLC, and IC analyses, respectively, and a possible pathway of PCP degradation in such a system was proposed.
- Competitive adsorption between PCP and oxalic acid, Fe species distribution, H2O2 formation, and a possible pathway of PCP degradation in a γ-Fe2O3/oxalate/UV system are investigated.
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