The removal of residual antibiotics, such as tetracycline (TC), from the environment is an important global grand challenge to combat an ever-increasing prevalence of antimicrobial resistance (AMR). Herein, a novel ternary deep eutectic solvent (DES) comprising choline chloride (ChCl), γ-valerolactone (GVL) and maleic acid (MA) to produce lignocellulosic nanofibers (LCNFs) from sunflower stalks which when combined with sodium alginate (SA) and polyacrylamide (PAM) afforded hydrogels for efficient removal of TC. The ternary ChCl/MA/GVL DES is highly effective for lignin removal (delignification efficiency, 91.70%). The physical properties of the LCNFs could be tailored with respect to temperature, i.e., with increasing temperatures, the lignin content ranged from 4.90 to 25.90%, the crystallinity index (CrI) from 31.85 to 45.66%, and size dispersity from 11.47 to 31.29 nm. The incorporation of obtained LCNF into SA/PAM hydrogels significantly enhanced their adsorption performance (92.3% vs 72.96%) for TC. Kinetic adsorption experiments revealed that chemical adsorption is mainly mechanism dominating the TC removal, and the pseudo- second-order model (Q e =79.24 mg g -1 ) was considerably closer to the experimental result (Q e = 69.71 mg g -1 ). The interactions between adsorbent and adsorbate were investigated via Langmuir and Freundlich models. The R² value for the Langmuir (0.981, 0.986, and 0.989, respectively) exhibited higher R²values (0.981, 0.986, and 0.989) in comparison with Freundlich model (0.937, 0.948, and 0.953), suggesting that the TC adsorption occurs via a monolayer process, with adsorption sites evenly distributed on the surface of hydrogels. The Freundlich constants were approx. 2.3, demonstrating the thermodynamic favorability of the adsorption process. The incorporation of LCNFs enhanced the removal rate of TC to a maximum of 92.3%, and the hydrogel still maintains relatively high adsorption capacity (49.87 mg·g - ¹) and removal rate (62.34%) for TC after four cycles. These findings demonstrate a practical approach to employing LCNFs for removing tetracycline antibiotics from water and, thus contributing to the fight against AMR.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)