Adsorption of Tetracycline From Water by a Kind of Recyclable Sodium Alginate/Polyvinyl Alcohol Granular Biochar Adsorbent

Abstract

The persistence and antibiotic resistance potential of tetracycline (TC) from livestock and poultry farming pose severe ecological and human health risks. To address this issue, we developed a recyclable S/N co-doped tea residue biochar (GSNTB), encapsulated within a matrix of sodium alginate (SA) and polyvinyl alcohol (PVA). Characteristic peaks in the FT-IR spectrum confirmed the presence of N- and S-containing functional groups on the adsorbent. Meanwhile, the x-ray photoelectron spectroscopy (XPS) results showed a decrease in the peak areas corresponding to N 1s at 398.6, 399.49, and 401.3 eV, as well as the peak areas of S 2p at 164.0 and 165.4 eV, confirming the involvement of nitrogen- and sulfur-containing groups in the reaction process. Adsorption followed the Langmuir model, yielding a 95.01 mg g⁻¹ maximum capacity. After five repeated uses, the removal efficiency of TC could reach over 85%. With its strong adsorption capacity, high mechanical strength, and excellent reusability, GSNTB shows great promise for practical use in treating wastewater.