[Adsorption of Tetracycline in Composite-polluted Water by Biochar from Industrial Production]

Compared to the laboratory preparation of biochar, there is less research on the adsorption of antibiotics by industrial production of biochar in water. In this study, three types of industrial production biochar （peanut shell biochar, sludge biochar, and perishable waste biochar） were selected, and their adsorption performance for tetracycline in composite-polluted water was systematically studied. The results indicated that the Freundlich equation could well fit the adsorption isotherms of the three types of biochar for tetracycline. At medium to high concentrations （>10 mg·L^-1）, the order of adsorption capacity of biochar for tetracycline was： perishable waste biochar > sludge biochar > peanut shell biochar. The aromaticity, hydrophobicity, and specific surface area of peanut shell biochar had important effects on its adsorption of tetracycline. The possible main adsorption mechanisms were π-π interaction, hydrophobicity, and pore filling. The specific surface area and pore volume of sludge biochar had a significant impact on its adsorption of tetracycline, and its possible main mechanisms included pore filling, surface complexation, and hydrogen bonding. The soluble organic carbon components and ash content of perishable waste biochar played a dominant role in its adsorption, with distribution being the main adsorption mechanism, followed by cation-π interaction and surface complexation. The effect of coexisting pollutants on the adsorption of tetracycline by biochar varied with the type of biochar. With the increase in ion strength and ammonia nitrogen concentration in the water, the adsorption capacity of peanut shell biochar for tetracycline showed a slight upward trend overall, whereas sludge biochar showed a slight downward trend. The adsorption of tetracycline on perishable waste biochar was not affected by ionic strength and ammonia nitrogen. Coexisting phosphates significantly reduced the adsorption efficiency of biochar for tetracycline, while coexisting aerobic organic compounds had no significant effect on the adsorption. The adsorption of tetracycline in water by sludge biochar and perishable waste biochar had good recyclable regeneration ability. The results of this study provide a reliable scientific basis and theoretical support for the engineering application of biochar in removing antibiotics from water.