Enhanced phosphate anion flux through single-ion, reverse-selective mixed-matrix cation exchange membrane

Phosphate recovery from wastewater is vital for both environmental sustainability and resource conservation, offering the dual benefit of reducing phosphate pollution while providing a valuable source of this essential nutrient. We previously reported an approach for synthesizing hydrous manganese oxide (HMO) nanoparticles within a polymeric cation-exchange membrane (CEM) to achieve a phosphate-selective mixed-matrix membrane (PhSMMM); however, the phosphate flux was lower than desired. Herein, we demonstrate a next-generation PhSMMM membrane with enhanced phosphate flux and selectivity. Experimental results confirm the successful incorporation of up to 28 wt% HMO nanoparticles into the polymeric CEM. The new PhSMMM exhibits a phosphate flux of 1.57 mmol∙m^–2.hr^–1 (an 8.5X enhancement), with selectivity over chloride, nitrate, and sulfate ions of 9, 11, and 104, respectively. This significant enhancement in phosphate flux marks a promising advancement in a sustainable solution for phosphate removal and recovery from wastewater.