Novel self-sustained flow-through electrochemical advanced oxidation processes using nano-Fe0 confined B, N co-doped carbon nanotubes/graphite felt cathode: Higher mineralization efficiency under wider pH

Abstract

To improve the mineralization efficiency of pollutants under wide pH ranges by self-sustained electrochemical advanced oxidation processes (EAOPs) without any reagent addition, a flow-through system based on the bifunctional cathode of B, N-doped carbon nanotubes embedded with nano-Fe0 particles that loaded on graphite felt (Fe@BN-C/GF) was developed. Dominant by 1O2 oxidation, the sulfamethazine (SMT) degradation rate and TOC removal in this recirculated flow-through system were 2.6 ∼ 3.3-folds and 1.4 ∼ 2.4-folds that of the batch system under the pH ranges of 3 ∼ 11, respectively. The SMT degradation performance was found not affected in the presence of HCO3–, NO3–, Cl-, K+, or humic acid (HA). The Fe@BN-C/GF cathode had more potential to treat enlarged wastewater by 5-folds during 10 h operation, and the SMT and TOC removal was 99% and 70.31%, respectively. The total phosphorus (TP), ammonia nitrogen (NH3-N) and TOC in reverse osmosis concentrate and secondary wastewater effluent could be simultaneously removed to <0.01 mg L-1 and 8 mg L-1 by this flow-through system with a low electric energy consumption (EEC) of 0.022 and 0.18 kWh gTOC-1, respectively. This EAOPs based on the flow-through Fe@BN-C/GF cathode was self-sustained, and had very promising application prospect of high mineralization of pollutants even for low-conductivity wastewater.