[Preparation of Tea Waste Biochar and Its Application in Tetracycline Removal from Aqueous Solution]

Tea waste biochar (TWBC) was prepared at 300℃, 500℃, and 700℃ under oxygen-limited atmosphere, and was characterized by elemental analysis, Brunauer-Emmett-Teller measurement, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. TWBC was then used to remove tetracycline from aqueous solution. The influences of solid-to-liquid ratio, pH, ionic types, and strength were investigated. The potential mechanism between tetracycline and TWBC was also explored. The results showed that the proper solid-to-liquid ratio was 4 g·L^-1. The pH of the solution had little influence on the removal of tetracycline. The inhibition effects of cation ions on tetracycline follows Mg²⁺ > Ca²⁺ > K⁺ > Na⁺. The NH₄⁺ in the solution can slightly promote the adsorption of tetracycline by TWBC700. However, the existence of Cu can decrease the adsorption effect of tetracycline by TWBC700. Increasing temperature can improve the adsorption effect of tetracycline by TWBC700. The pseudo-second-order and Langmuir model can well fit the adsorption process of tetracycline onto TWBC. The adsorption capacity of tetracycline by TWBC was TWBC700 > TWBC500 > TWBC300. The mechanisms of tetracycline by TWBC referred to the pore-filling effect, hydrogen binding, and π-π interaction. Therefore, high-temperature TWBC has the potential to act as an adsorbent for removing tetracycline from wastewater.