Sustainable Polylactic Acid–Enhanced Biowaste Composite for Tetracycline Adsorption

ABSTRACT The development of adsorbent materials from renewable and biodegradable sources stands out as a green approach for removing pharmaceutical‐based contaminants. In the current research, composites of walnut shell (WS), an agricultural waste, and polylactic acid (PLA) at various ratios were created, and the adsorption performance of these novel biocomposites for tetracycline (TC) was thoroughly evaluated. The composites synthesized using the melt‐compounding method and containing various PLA ratios were characterized using FT‐IR, SEM, and BET analyses. Sample WS@PLA0.9 showed superior performance with the highest surface area (18.05 m ² g ⁻¹ ) and maximum adsorption capacity (6.62 mg g ⁻¹ ). The monolayer Langmuir isotherm model provided the best fit to the equilibrium data, whereas the adsorption kinetics were described by a pseudo‐second order model, with chemical interactions dominating. Thermodynamic results revealed that TC adsorption was endothermic, spontaneous, and progressively disordered. The adsorbent WS@PLA0.9 retained its high efficiency through three reuse cycles; however, the efficiency decreased slightly due to ionic interference in real water matrices. The findings suggest that PLA‐supported WS has high potential for removing pharmaceutical contaminants as a sustainable, low‐cost, and effective alternative.