Removal of tetracycline in the water by a kind of S/N co-doped tea residue biochar.

Abstract

Tetracycline (TC) is widely present in the environment, and adsorption technology is a potential remediation method. S/N co-doped tea residue biochar (SNBC) was successfully prepared by hydrothermal carbonization method using tea residue as raw material. S was doped by Na₂S₂O₃·5H₂O, and N was doped by N in tea residue. The adsorption efficiency of SNBC could reach 94.16% when the concentration of TC was 100 mg L^-1. The adsorption effect of SNBC on TC was 9.38 times more than that of unmodified biochar. Tea biochar had good adsorption effect at pH 4-9. The maximum adsorption capacity of 271 mg g^-1 was calculated by the Langmuir isotherm model. The adsorption mechanism involved many mechanisms such as pore filling, π-π interaction and hydrogen bonding. The adsorbent prepared in this study could be used as an effective adsorbent in the treatment of TC wastewater.