Removal of diclofenac from water by zeolite-assisted advanced oxidation processes

• We studied diclofenac (DCF) removal by heterogeneous photo-Fenton process with FeZSM5 catalyst.
• Degradation mechanism includes surface complexation with Fe(III) and subsequent degradation by UV-A.
• UV-A/FeZSM5/H2O2 process resulted in significant improvement in biodegradability and toxicity of DCF aqueous solution.
• FeZSM5 catalyst showed good stability and activity through consecutive runs.

The goal of the study was to evaluate the performance of zeolite-assisted advanced oxidation processes for the removal of diclofenac (DCF) in water matrix. Heterogeneous Fenton type catalyst (FeZSM5) was prepared by solid-state ion exchange and characterized by SEM/EDS and ICP/MS analyses. The uniform distribution of iron and atom economy was established. The influence of key operating parameters of applied UV-A/FeZSM5/H2O2 process on the activity of zeolite catalyst was investigated using statistical modeling. The results obtained revealed the contribution of adsorption and oxidative degradation to the overall treatment effectiveness, whereas the oxidation became dominant at the end of the treatment. UV-A/FeZSM5/H2O2 process applied at optimal conditions determined within the investigated range (pH 4, [H2O2] = 50 mM and [Fe]FeZSM5 = 2.0 mM) resulted in significant improvement in biodegradability and lower toxicity after 2 h treatment of DCF aqueous solution. The used catalyst showed good stability and retained its catalytic activity in consecutive runs, which was documented by low iron leaching and similar consumption of oxidant in repetitive cycles.

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