Tetracycline adsorption mechanisms by NaOH-modified biochar derived from waste Auricularia auricula dregs

Tetracycline (TC) is not easy to degrade in human or animal and can even be converted to more toxic substances. The overuse and wanton discharge of TC also caused serious problem of water pollution. This study investigated the removal of TC by biochar (BC) prepared from waste Auricularia auricula dregs and modified with NaOH by characterizing the pH and adsorption kinetics, and using isotherm models. Three BC samples were prepared and that produced using the highest concentration of NaOH (8 M) was more suitable for removing TC, where the adsorption amount was 26.65 mg/g. Pseudo-second order and Freundlich models both fitted well to the adsorption kinetics, and diffusion of the liquid film was considered the rate-controlling step. The multivariate mechanism involved electron interplay, H-bonding, and pi-pi electron donor-acceptor interactions. The results of this work can not only make the waste Auricularia auricula dregs resourceful, but also provide a new method for the removal of TC in wastewater, which is of great practical significance.

Automated summary

This study investigated the removal of tetracycline by using biochar prepared from waste Auricularia auricula dregs, showing that biochar produced with the highest concentration of NaOH (8 M) was the most effective in removing tetracycline with an adsorption amount of 26.65 mg/g. Both pseudo-second order and Freundlich models fit well to the adsorption kinetics, with liquid film diffusion considered as the rate-controlling step. The multivariate mechanism involves electron interplay, H-bonding, and pi-pi electron donor-acceptor interactions.