Renewable Adsorbents for Selective Phosphorus Removal: Co(OH)2-Derived ZIF-67 on Anion Exchange Resin

Metal organic framework (MOF)-basedadsorbents are appealingforremoving low-concentration phosphates with interfering ions in wastewaterpurification, a new strategy developed to maintain the good activityof metal sites. Here, ZIF-67 was immobilized onto the porous surfaceof anion exchange resin (D-201) with a high loading amount of 22.0wt % by a modifiable Co(OH)(2) template. We observed thatthe removal rate of low-concentration phosphate (2 mg P/L) by ZIF-67/D-201nanocomposites was 98.6%, and more than 90% phosphate adsorption capacitywas still maintained, with 5 times molar concentration of interferingions in the solution. Moreover, after six times of regeneration bysolvothermal reaction in the ligand solution, the structure of ZIF-67was better preserved in D-201 with more than 90% phosphate removalrate. ZIF-67/D-201 could be employed effectively in fixed-bed adsorptionruns. By the analysis of experiment and characterization, we foundthat during the adsorption-regeneration process of ZIF-67/D-201for phosphate, reversible structural transformation of ZIF-67 andCo(3)(PO4)(2) occurred in D-201. In general,the study reported a new method to develop MOF adsorbents for wastewatertreatment.