Highly selective and efficient phosphate removal from water bodies using triethanolamine-assisted glycine-intercalated layered double hydroxide composites

Developing highly selective phosphate adsorbents with abundant binding sites presents a significant challenge. In this study, we synthesized an amine-functionalized hydrotalcite (TEA-Gly-LDH) with a high specific surface area using triethanolamine and glycine, which was employed as an adsorbent for capture phosphate from water. We report the phosphate adsorption properties, isothermal behavior, and adsorption kinetics. The results indicate that TEA-Gly-LDH exhibits a higher adsorption capacity and a faster adsorption rate, achieving equilibrium within 2 hours at 25 °C. The removal rate reached as high as 96 %, with an adsorption capacity of 59.43 mg/g, which is 11 % greater than that of unmodified hydrotalcite. Furthermore, it maintains a high phosphate adsorption capacity across a wide pH range of 3–11. Additionally, TEA-Gly-LDH demonstrates excellent selectivity for phosphate, with a distribution factor of 2.73 × 10 4 in a mixed-ion system, surpassing the 2.39 × 10 3 of unmodified hydrotalcite. The adsorption capacity is preserved even after five regeneration cycles. The adsorption data fit well to the Langmuir isotherm model, suggesting that phosphate adsorption is a monolayer chemisorption process. Kinetic studies reveal that the material's adsorption behavior is primarily governed by ion exchange, adsorption at surface active sites, and intraparticle diffusion.