Highly efficient activation of ferrate (VI) via corncob biochar assisted by electrochemistry for the removal of sulfamethoxazole from water

Abstract

Ferrate [Fe (VI)] has been shown to be an effective oxidant for pollutants degradation. However, its propensity to self-decompose in water has limited its application. In this study, a novel method was developed for the activation of Fe (VI) using corncob biochar (CBC) with assistance of electrochemistry (EC/Fe (VI)/CBC), aiming to continuous activation of Fe (VI) for the removal of sulfamethoxazole (SMX) from water. Experimental results showed a remarkable SMX removal efficiency of 99.23 %, with simultaneous removal of over 49.68 % of the total organic carbon (TOC) within 60 min (C0 (Fe (VI)) = 0.50 mM, C0 (SMX) = 0.02 mM, E = 25 V, mCBC = 20 mg). The electrochemistry was introduced to guarantee the regeneration of the functional groups on CBC, among which the CO was the possible active site for activation of Fe (VI). Excessive background constituents (NO3–, SO42-, HCO3–, and HA) and high pH were critical influencing factors. The results of cyclic experiments and SMX removal in different real water have demonstrated the stability and potential practical applications of the EC/Fe (VI)/CBC system. The quenching, electron paramagnetic resonance, and probe experiments revealed that 1O2 and Fe (V)/Fe (IV) were identified as the primary active species responsible for the SMX degradation. Theoretical calculation further revealed that the N atoms of SMX were susceptible to be attacked by the reactive species. Subsequently, the SMX was transformed into non-toxic or less toxic products. This work suggested that the combination of electrochemistry and biochar to activate Fe (VI) was a promising technology for antibiotics elimination.