Preparation of resin-based composites containing Ce and cationic polymers with abundant promotional affinity sites for phosphate capture

Abstract

The eutrophication of water bodies caused by excessive phosphate discharge has always been a hotspot issue that needs to be addressed urgently. However, the fabrication of a practical capturer with high phosphate affinity remains a challenging task. In this work, a novel type of composite adsorbent (D301-Ce⁺) was synthesized, aiming for efficient and selective phosphate capture from wastewater. Characterizations including FTIR spectroscopy, XRD, and SEM confirmed the successful synthesis of the composites with multiple functionalities. It was shown that the maximum phosphate adsorption capacity of D301-Ce⁺ was 246.74 mg P g⁻¹ because of the porous matrix of the weak basic anion exchange resin of D301 jointly modified with cerium and cationic polymeric layers. Adsorption kinetics and thermodynamics experiments confirmed that the intra-particle diffusion dominated phosphate adsorption, and the process was spontaneously endothermic naturally. Recycling studies indicated that this newly fabricated sorbent behaved with excellent reusability. Most importantly, in the presence of coexisting anions (Cl⁻, NO₃⁻, SO₄²⁻, and HCO₃⁻), D301-Ce⁺ exhibited a strong selectivity for phosphate, which could be attributed to the high affinity of the cerium component toward phosphate. For practical purposes, fixed-bed column experiments demonstrated that the Thomas model fitted the parameters better. By virtue of component optimization and sorption testing, the capturing mechanism could be fully described as electrostatic attraction and inner-sphere complexation.