New Strategy To Enhance Phosphate Removal from Water by Hydrous Manganese Oxide

摘要

Hydrous manganese oxide (HMO) is generally negatively charged at circumneutral pH and cannot effectively remove inionic pollutants such as phosphate. Here we proposed a new strategy to enhance HMO-mediated phosphate removal by immobilizing nano-HMO within a polystyrene anion exchanger (NS). The resultant nanocomposite HMO@NS exhibited substantially enhanced phosphate removal in the presence of sulfate, chloride, and nitrate at greater levels. This is mainly attributed to the pH_(pzc) shift from 6.2 for the bulky HMO to 10.5 for the capsulated HMO ninoparticles, where HMO nanoparticles are positively charged at neutral pH. The ammonium groups of NS also favor phosphate adsorption through the Donnan effect Cyclic column adsorption experiment indicated that the fresh HMO@NS could treat 460 bed volumes (BV) of a synthetic influent (from the initial concentration of 2 mg P[PO_4~(3-)]/L to 0.5 mg P[PO_4~(3-)]/L), while only 80 BV for NS. After the first tune of regeneration by NaOH-NaCl solution, the capacity of HMO@NS was lowered to ～300 BV and men kept constant for the subsequent 5 runs, implying the presence of bom the reversible and irreversible adsorption sites of nano-HMO. Additional column adsorption feeding with a real bioeffluent further validated great potential of HMO@NS in advanced wastewater treatment This study may provide an alternative approach to expand the usability of other metal oxides in water treatment.