Highly energy-efficient removal of acrylonitrile by peroxi-coagulation with modified graphite felt cathode: Influence factors, possible mechanism

A highly energy-efficient peroxi-coagulation (PC) process was developed based on modified graphite felt, and the acrylonitrile removal efficiency was also comparatively studied by electro-Fenton (EF) and electrocoagulation (EC). The results showed that acrylonitrile was slowly and ineffectively removed by EC and EF, whereas by PC it was not only more rapid, but also effective at wide pH ranges of 3.0-9.0, which overcame the pH limitations for EC and EF. In addition, the electric energy consumption (EEC) of EF, EC and PC was 36.01, 14.43 and 3.08 kWh/kg respectively, suggesting PC was more economical. The influence of important operating factors such as pH, applied current and initial concentration were investigated for these three processes. The production of (OH)-O-center dot and transformation of iron ions were analyzed to explore the mechanisms of PC process. Compared to conventional treatment methods, PC was more cost-effective due to the combined action of (OH)-O-center dot as well as the coagulation with the formed Fe(OH)(3) precipitate. Primary intermediates were identified by GC-MS analysis, and a possible pathway was proposed by the action of (OH)-O-center dot in EF and the hydrogenation in EC. This work demonstrated that PC is cost-effective and has potential for the degradation of acrylonitrile.