• La(OH) 3 @MMCH exhibits high phosphate adsorption capacity of 105.72 mg P/g. • La(OH) 3 @MMCH performs effectively over a wide pH range between 3.0 and 9.0. • MMCH shows the enhanced surface charge density and Donnan membrane effect. • Phosphate adsorption efficiency in actual surface water reaches 95.21%. • Phosphate removal is achieved through electrostatic attraction and ligand exchange. Cationic hydrogels have received great attention to control eutrophication and recycle phosphate. In this study, a type of La(OH) 3 loaded magnetic MAPTAC-based cationic hydrogel (La(OH) 3 @MMCH) was developed as a potential adsorbent for enhanced phosphate removal from aqueous environment. La(OH) 3 @MMCH exhibited high adsorption capacity of 105.72±5.99 mg P/g, and reached equilibrium within 2 hr. La(OH) 3 @MMCH could perform effectively in a wide pH range from 3.0 to 9.0 and in the presence of coexisting ions (including SO 4 2−, Cl−, NO 3 −, HCO 3 −, SiO 4 4− and HA). The adsorption-desorption experiment indicated that La(OH) 3 @MMCH could be easily regenerated by using NaOH-NaCl as the desorption agent, and 73.3% adsorption capacity remained after five cycles. Moreover, La(OH) 3 @MMCH was employed to treat surface water with phosphate concentration of 1.90 mg/L and showed great removal efficiency of 95.21%. Actually, MMCH showed high surface charge density of 34.38-59.38 meq/kg in the pH range from 3.0 to 11.0 and great swelling ratio of 3014.57% within 24 h, indicating that MMCH could produce the enhanced Donnan membrane effect to pre-permeate phosphate. Furthermore, the bifunctional structure of La(OH) 3 @MMCH enabled it to capture phosphate through electrostatic attraction and ligand exchange. All the results prove that La(OH) 3 @MMCH is a promising adsorbent for eutrophication control and phosphate recovery. [Display omitted] [ABSTRACT FROM AUTHOR]