Adsorption properties and mechanism of suaeda biochar and modified materials for tetracycline

Adsorption was an available way to eliminate Tetracycline (TC) from waste water. Suaeda biochar (800SBC) and iron modified biochar (Fe–800SBC) were prepared using pyrolysis under oxygen-limiting conditions. BET and SEM showed that the surface of Fe–800SBC was rougher, and the specific surface area (SBET) was 7 times that of 800SBC. There existed pore filling, ion exchange, metal ion complexation, hydrogen bonds and cation-π interaction mechanism. Both 800SBC and Fe–800SBC conformed to quasi-second-order kinetics model, belonged to chemisorption. Fe–800SBC conformed to Elovich model too. The adsorption process of 800SBC conformed to Freundlich and Sips L-F models, Fe–800SBC conformed to the Sips L-F and Temkin models, identifying the presence of physical and chemical adsorption during adsorption. Response surface method (RSM) was used to optimize important process parameters. The quadratic model was sufficient to predict TC removal response in the range of studied parameters.