Separation of Phosphate from Wastewater Using an Ion Exchanger Based on Chitosan

Abstract

Phosphate is a key contaminant that induces eutrophication in rivers, ponds and reservoirs. To control phosphates in wastewater, we developed a chitosan-bead-based ion exchanger using Cu2+ for immobilization. Changing the initial conditions, we investigated its phosphate removal efficiency from solutions. The optimal initial concentrations of chitosan, acid and base were determined to be 2.5% (w/w) chitosan, 1% (v/v) HCl, and 1M NaOH to maintain bead shape. The additional step of crosslinking reduced uptake (efficiency) by up to 10% due to the loss of amino group active sites. The phosphate removal efficiency was proportionally increased by copper uptake. A concentration of 5,000 mg/L of copper could achieve stable physical strength. The maximum phosphate uptake was 89 mg/g, fitted with a Langmuir equation. When 10% NaCl was used as a regenerate, the regeneration efficiency gradually decreased from 75% to 40% through seven cycles.