Synthesis of a Novel Ambipolar Resin Membrane for Ion Adsorption

Abstract

ABSTRACT We have synthesized a novel composite ambipolar resin membrane with a high water absorption capacity (150−200%) and superior ion adsorption properties. The ambipolar membrane was capable of adsorbing nitrate, ammonium, potassium and phosphorus simultaneously from aqueous solutions. The adsorption capacity of the membrane varied with ionic concentration and composition. Thus, from a mixed solution of 30 mmol…L− 1NH4 + and 10 mmol…L− 1 each of NO3 −, K+, and H2PO4 −, the synthetic membrane was able to take up 0.241 mmol NH4 +, 0.151 mmol NO3 −, 0.120 mmol K+, and 0.046 mmol H2PO4 − per g membrane. A large proportion (73.9−92.5%) of the adsorbed ions could be desorbed with dilute (5%) HCl. The rate of desorption is inversely related to the cross-linking density of the membrane. The competition between NO3 −and H2PO4 − as well as between K+ and NH4 + was also investigated.