Phosphorus removal from water by the layered double hydroxides (LDHs)-based adsorbents: A review for structure, mechanism, and current progress
Degui Gao, Wentao Zhang, Hao Dong, Yifan Yu, Weiping Liu, Hang Luo, Zibo Jing, Baorui Liang, Lele Peng, Bingdang Wu, Tianyin Huang, Hui Cheng
Abstract
Phosphorus (P) is an essential macronutrient for organism growth, but human activities in industry, agriculture, and daily life have significantly disrupted its natural cycle. The excessive discharge of P into water bodies leads to eutrophication, endangering aquatic ecosystems. Recycling and reusing P, while improving its utilization efficiency, are critical for addressing this issue. Layered double hydroxides (LDHs), as tunable layered inorganic materials with large specific surface areas and high porosity, show great promise for wastewater treatment. This paper evaluates the potential of LDHs for P removal and recovery, examining key adsorption mechanisms—ion exchange, electrostatic attraction, complexation, and intermolecular forces, and factors such as initial P concentration, pH, temperature (T), and coexisting ions. Initial P concentration is the most influential factor, with higher T enhancing adsorption and increased pH inhibiting it. Coexisting ions, despite competitive effects, generally promote adsorption. Challenges, including high production costs, limited selectivity, mechanical instability, and potential biotoxicity, are discussed alongside strategies to address them, such as cost-effective synthesis, defect engineering, and composite materials. Future research should focus on developing scalable, eco-friendly LDHs with high stability, regeneration capacity, and efficiency in real-world conditions. Addressing these challenges could position LDHs as key materials for sustainable P management and restoration of the natural P cycle. • The mechanisms of phosphorus (P) removal and recovery via LDHs is presented. • The factors affecting P adsorption with LDHs are summarized. • The application cases of LDHs in phosphate removal and recovery are reviewed. • The challenges and future prospects of LDHs for P removal and recovery are proposed.