Improving the yield and tetracycline adsorption performance of kitchen waste biochar through subcritical dimethyl ether pretreatment

In the context of low-carbon development, it is important to promote resource utilization of kitchen waste, which has the dual properties of pollution and resources. In this study, we explored a method to enhance biochar yield and tetracycline adsorption performance using subcritical dimethyl ether (DME) dewatering and lipid-extraction pretreatment. The mechanism of the effect of lipids and moisture on pyrolysis was investigated by comparing the differences among solid residue biochar, kitchen waste biochar, and dry kitchen waste biochar. Meanwhile, the adsorption performance and mechanism of solid residue biochar on tetracycline was clarified. It was found that lipids did not participate in the generation of biochar, but their decomposition products adhered to the biochar surface. Through DME pretreatment, 95.12% of lipids and 61.34% of moisture could be removed from kitchen waste, the biochar yield was increased by at least 22.77%, and the specific surface area and pore capacity were enhanced. The adsorption performance of tetracycline on solid residue biochar reached 79.11 mg center dot g(-1), and the potential adsorption mechanisms included pi-pi interaction, hydrogen bonding and pore filling.