Efficient Removal of Tetracyclines and Their Metabolites from Wastewater Using Purified Stevensite: Adsorption Capacity, Reusability, and Antibiotic Decontamination

Abstract

Background/Objectives: The persistence of tetracycline residues in aquatic environments poses substantial risks to ecosystems and public health, emphasizing the need for effective removal strategies. This study examines the use of purified stevensite (ST), a natural clay mineral, as an efficient and cost-effective adsorbent for removing tetracycline antibiotics from contaminated water. Methods: Batch experiments were conducted to assess the adsorption kinetics, isotherms, and influence of environmental factors. Material characterization studies were performed before and after tetracycline adsorption. Results: ST demonstrated optimal removal efficiency at an acidic pH, achieving over 99% elimination of both tetracyclines and their metabolites at an adsorbent dose of 2 g L⁻¹ and antibiotic concentration of 5 mg L⁻¹. Equilibrium was reached within 30 min. Regeneration experiments confirmed that ST retained over 90% of its adsorption capacity after five adsorption–desorption cycles. Surface characterization revealed that ST’s large surface area, high cation exchange capacity, and potential for hydrogen bonding may explain its high adsorption capabilities. The material was tested on real samples of tap water, surface water, and wastewater, demonstrating an effective removal rate over 99%. Conclusions: With its high efficiency, low cost and favourable reusability, purified ST is a promising option for large-scale wastewater treatment, contributing to safer water resources and improved environmental protection.