Synthesis of ZnFe2O4/B,N-codoped biochar via microwave-assisted pyrolysis for enhancing adsorption-photocatalytic elimination of tetracycline hydrochloride

B, N-codoped biochar was modified by ZnFe2O4 (ZnFe/BN-biochar) via the one-pot microwave-assisted pyrolysis for enhancing the adsorption-photocatalytic elimination of tetracycline hydrochloride (TCH). The addition of ZnFe2O4 could enhance the adsorption and photocatalytic capacity of B,N-codoped carbon under solar light irradiation. Among these composites, the optimal 3-ZnFe/3b-BN-biochar could remove 98.19 % of 150 mg L−1 TCH solution within 120 min, and its adsorption capacity estimated by Langmuir was 244.34 mg g−1 for TCH removal. However, the removal efficiency of TCH over 3-ZnFe/3b-BN-biochar decreased to 89.45 % after seven cycles. The photocatalytic and adsorption kinetics of biochar-based composites for TCH removal were well descried with Langmuir-Hinshelwood and second-order models, respectively. In addition, Langmuir well fitted with the adsorption isotherms of biochar-based composites. The adsorption process of TCH over 3-ZnFe/3b-BN-biochar was a spontaneous and physisorption process. Hence, 3-ZnFe/3b-BN-biochar was a promising material for the adsorption and photocatalytic elimination of pollutants in wastewater.