A facile approach to lignin-based biochar derived from black liquor and the study of its removal to tetracycline from water.

The present study focuses on preparing lignin-biochar (L-Bio) from papermaking black liquor-lignin and the study its effectiveness and mechanism in removing tetracycline (TC) from water. Results showed that the yield, BET surface area and pore size of L-Bio were 36.3707-40.2567 %, 392.2232-625.3296 m•g and 2.244-1261.915 μm, respectively. Adsorption experiment results showed that Bio-800 °C has the maximum adsorption capacity of 243.9067 mg•g and it has the best removal effect on TC under neutral conditions. Adsorption kinetics results showed that the quasi second-order kinetic equation can reflect the process better, which indicates that the adsorption process is mainly chemical adsorption. The possible mechanism was proposed. It mainly includes pore filling, ion exchange, electrostatic interaction, hydrogen bonding, etc. The objectives of the study were to (1) provide a new approach for the resource utilization of lignin and achieve waste to waste conversion; (2) analysis the relationship between the structure and properties of L-Bio and propose its possible mechanism for removing TC from water, which can provide theoretical support for L-Bio's practical application.