Adsorption of phosphate from aqueous solution by lanthanum modified macroporous chelating resin

A highly effective adsorbent of lanthanum-modified D751 resin (D751 resin for macroporous styrene chelated resin, sodium form) was prepared to enhance the effect of removing phosphate from solution. FTIR, SEM were used to explore the functional groups and structural features on the surface of D751-La; XPS analyzed the action mechanism between phosphate and D751-La. The adsorption performance about D751-La toward phosphate was investigated by batch experiment. The results showed that Langmuir, Freundlich, Temkin, Koble-Corrigan as well as Redlich-Peterson models fitted well for the adsorption isotherms. The adsorption kinetics could be better fitted by Double Constant, Elovich, and Pseudo-second-order model. The effect of salinity was not significant, such as Cl⁻ and SO₄²⁻. When the solid-liquid ratio was 15 g·L⁻¹ with setting the reaction time as 8 h, the unit adsorption quantity of D751-La to phosphate (calculated in P) reached up to 26.3mg·g⁻¹ under the solution pH=3 at 293 K. The process was spontaneous and exothermic from thermodynamic analysis. It shows that D751-La has potential to remove phosphate from solution.