Ion-exchange properties of 2,2’-dihydroxybiphenyl urea - formaldehyde terpolymer resins

A number of resins have been synthesized by reacting 2,2’-dihydroxybiphenyl with urea and formaldehyde in presence of 2M HCl as catalyst, proved to be selective chelating ion-exchange resins for certain metals. Chelation ion-exchange properties of these terpolymer were studied for Fe3+, Cu2+, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+ ions. A batch equilibrium method has been employed in the study of the selectivity of metal ion uptake involving the measurements of the distribution of a given metal ion between the polymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The terpolymer showed higher selectivity for Fe3+, Cu2+ and Ni2+ ions than for Co2+, Zn2+, Cd2+ and Pb2+ ions.

1. It is selective chelating ion-exchange resin for Fe3+, Cu2+, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+ metal ions. 2. These resins showed a higher selectivity for Fe3+, Cu2+ and Ni2+ ions as compared to Zn2+, Cd2+ and Pb2+ ions. 3. These polymers showed higher selectivity for Fe3+ at pH 2.5 as compared to other metal ions. 4. The amount of metal ions taken up by the BPhUF terpolymer resins increases in the order: BPhUF-1 < BPhUF-2 < BPhUF-3 < BPhUF-4. It may be due to the introduction of more and more ligand groups (Urea monomers) in the repeating unit of the terpolymer resins. Acknowledgment The authors are thankful to Head of the Department of Chemistry for providing the laboratory facilities. List of abbreviations BPh UF A.R. HCl HNO3 NaOH NaNO3 D h 2,2’-dihydroxybiphenyl Urea Formaldehyde terpolymer; Analytical grade; Hydrochloric Acid; Nitric Acid; Sodium Hydroxide; Sodium Nitrate; Distribution ratio; hour.