Lanthanum hydroxide showed best application potential in La-based materials based on its stable phosphate adsorption properties in complex water environments.

Three lanthanum morphology materials encompassing all lanthanum composites were synthesized by the direct precipitation method, and their phosphate adsorption order was determined as La(CO) > La(OH) > LaO. Further comparison of the adsorption performance between La(CO) and La(OH) revealed that the former exhibited a twofold higher rate of adsorption compared to the latter. The presence of SO, HCO, Mg, and HA in the water led to a decrease in the phosphate adsorption of La(CO) and La(OH), while Ca enhances the adsorption of phosphoric acid by both materials. Compared to La(CO), La(OH) exhibited stronger resistance against coexisting ions. The pH was the limiting factor for phosphate adsorption in both cases, and their adsorption capacity decreased significantly as the pH increased. The phosphate adsorption mechanism of La(CO) was ligand exchange to form inner-sphere complexes, while the phosphate adsorption mechanism of La(OH) involved ligand exchange, inner-sphere complexation, and electrostatic attraction. The stability of La(OH) exhibited superior performance compared to that of La(CO) over 5 adsorption-desorption cycles. Although La(CO) had a higher initial phosphate adsorption capacity than La(OH), its phosphate adsorption capacity decreased by 40% after five adsorption-desorption cycles, while that of La(OH) decreased by 2.3%. Additionally, the amount of La(OH) adsorbed after five cycles was 25.6% higher than that of La(CO). Therefore, La(OH) performs better regeneration adsorption than La(CO). Furthermore, a smaller dosage of La(OH) was required compared to La(CO) in a test aimed at lowering the actual phosphate concentration in water to 0.5 mg/L. In summary, La(OH) is a more suitable substrate for cyclic adsorption for phosphorus removal than La(CO) and has better potential for practical application. In conclusion, La(OH) proves to be a more suitable substrate for cyclic adsorption in phosphorus removal compared to La(CO) and exhibits superior potential for practical application.