Joule heat mediated by graphite felt enhances peroxymonosulfate activation and carbamazepine degradation: Efficiency and mechanism

Abstract

Thermal activation of persulfate (PS) is a simple and effective method to generate sulfate radicals (SO4̇‾) for pollutant degradation but its practical application was severely restricted by the excessive energy consumption. In this study, a low energy consumption but efficient Joule heat-activation strategy was developed. The temperature of the reaction solution (TRS) rose to 76.9 °C within 30 min after 5 V external voltage (Uex) was applied onto the two sides of a graphite felt (GF) with the thickness of 6 mm (GF-6). Correspondingly, the peroxymonosulfate (PMS) decomposition ratio and the degradation efficiency of carbamazepine (CBZ) reached 82.6 % and 97.5 %. The catalytic activation of PMS on the surface of GF was the dominant pathway to generate free radicals during the Joule heating process rather than the heat-activation pathway. More importantly, removing per milligram of CBZ only consumed 5.6 kJ electric energy which was significantly lower than that of the common heating methods (namely, 80 °C water bath heating and electrical heating at 5 V using a commercially available ceramic electric heating rod). Impressively, this Joule heating system exhibited wide applicability and prominent reusability. Overall, this work developed an effective PMS thermal activation strategy with low power consumption using the widely available GF and realized efficient degradation of typical organic pollutants.