Functionalized PolyHIPE polymer monoliths as an anion-exchange media for removal of nitrate ions from aqueous solutions

Monolithic anion exchanger PolyHIPE media were used for the removal of nitrate anions from aqueous solutions. Both equilibrium and column adsorption tests and regeneration tests were carried out. The suitability of the Langmuir adsorption model to the equilibrium data was investigated. The maximum adsorption capacity was 0.215meq/g as per Langmuir isotherm at 20 degrees C. At a flow rate of 5ml/min (corresponding flux was 1.0cm/min) and 150mg/L nitrate feed concentration, breakthrough capacity and apparent capacity were 1.336meq /g resin and 2.842meq /g resin, respectively. Column experimental tests were conducted to provide data for theoretical modeling and to verify the system performance of the process. The theoretical column model adopted in this work was found to describe well, the ion-exchange breakthrough characteristics. After reaching equilibrium adsorption capacity, the monoliths were regenerated using 1N HCl and were subsequently retested. It was found that the regeneration efficiency reduced from 99% after second usage to 95% after the third usage.