Mechanistic insights into efficient phosphorus adsorption and recovery from water using functional ZnO/ZnFe-LDHs alginate hydrogels

This study is devoted to the development of zinc oxide/zinc-iron layered hydroxide/alginate hydrogel composites (ZnO/LDHs/Alg), aiming to improve the removal and recovery efficiency of phosphate in aqueous solution. The results show that the maximum phosphate adsorption capacity of the composite material reaches 17.06 mg/g, which is better than that of traditional adsorption materials such as bentonite, biochar, and zeolite. The main adsorption mechanisms involve electrostatic attraction, hydrogen bonding, ligand exchange, and ion exchange. After the adsorption is completed, the ZnO/LDHs/Alg composite material can achieve efficient recovery of phosphate through a simple filtration operation, and the recovery efficiency is as high as 96.81 %. It is worth mentioning that even after five consecutive adsorption-desorption cycles, the removal rate of phosphate can still be maintained at more than 90 %. In summary, ZnO/LDHs/Alg hydrogels represent a highly promising solution for the sustainable removal and recovery of phosphorus from aqueous environments, offering significant potential for environmental applications.