Highly Efficient Phosphate Removal By Polymeric Anion Exchanger Containing Poorly Crystalline Nano-hydrated Manganese Dioxide

Excessive phosphorus is generally considered as a dominant factor responsible for the eutrophication of water bodies. Currently, how to achieve highly efficient phosphate removal from water is still a challenging task to meet increasingly stringent regulations on phosphate discharge.Hydrated manganese dioxide is an environmental friendly material for pollutant removal through oxidation and/or sorption. In the current study, a polymeric hybrid adsorbent HMO-201was fabricated by immobilizing poorly crystalline hydrated manganese dioxide (HMO) within a macroporous anion exchange resin D-201. The resulting nanocomposite was examined for the enhanced phosphate removal from aqueous solutions. Batch adsorption experiments indicate that HMO-201exhibits favorable sorption toward phosphate even in the presence of some competing anions like sulfate and chloride. Adsorption equilibrium could be reached within180min. Fixed-bed column tests indicate that phosphate adsorbed by HFO-201from the synthetic waters results in the decrease of P from2mg/L to<0.5mg/L, with the treatment capacity of510bed volume (BV), while that for D-201was less than60BV under otherwise identical conditions. Moreover, P adsorbed by HMO-201was amenable to efficient desorption with a binary NaOH-NaCl solution without any significant Mn capacity loss. The repeatability of the composite adsorbent needs further improvement, and the underlying mechanism was not clear.