Enhanced electrochemical removal of sulfadiazine using stainless steel electrode coated with activated algal biochar

With the increasingly discharging and inappropriately disposing of antibiotics from human disease treatment and breeding industry, extensive development of antibiotic resistance in bacteria raised serious public health concern. In this work, algal biochar was coated onto the stainless steel mesh, and was employed as cathodic electrode for the degradation of sulfadiazine (SDZ) in an electro-Fenton (EF) system. It was found that algal biochar pyrolyzed at 600 degrees C with 1:1 KOH achieved best catalytic performance to generate H2O2 via oxygen reduction. Moreover, removal efficiency of SDZ reached 96.11% in 4 h with an initial concentration of 25 mu g/mL, under the optimized condition as: initial pH at 3, 50 mM of Na2SO4 as electrolyte and an applied current of 20 mA/cm(2). In addition, it was found that the SDZ removal kept at about 96.99% even after four repeated degradation process. Moreover, four possible SDZ degradative pathways during the EF process were proposed according to determined intermediates, model optimization and density functional theory calculation. Finally, acute and chronic biotoxicity of the degradative products against fish and green algae was evaluated, to further elaborate the environmental impact of SDZ after electrochemical degradation.

Automated summary

In this study, algal biochar was used as a cathodic electrode in an electro-Fenton system to successfully degrade sulfadiazine. The use of algal biochar resulted in efficient removal of sulfadiazine, with H2O2 playing a crucial role in the degradation process. Four possible degradation pathways of sulfadiazine were proposed, and the biotoxicity of the degradation products on fish and green algae was evaluated.