Novel Polymeric Adsorbents Bearing Amide, Pyridyl, Azomethine and Thiourea Binding Sites for the Removal of Cu(II) and Pb(II) Ions from Aqueous Solution

Abstract

Novel polyamides bearing pyridyl and azomethine groups as pendant pyridylformylimino groups along with thioamide moieties in the polymer backbone were synthesized using 4-pyridylformylimino-N-(phenyl,2′,5′-dicarboxylic acid) with 4,4′-(bisthiourea)benzidine and 4,4′- diaminodiphenyl methane through one pot phosphorylation polymerization technique. The optimization of experimental conditions and parameters including pH, adsorbent dosage, contact time, and initial metal ion concentration for the removal of heavy metal has also been investigated. Kinetic studies showed that the pseudo second order rate equation fits well with experimental values. The FT-IR spectrum indicated that the pyridine, amide, amide carbonyl, and azomethine groups were the major binding sites with metal ions. The maximum adsorption capacities of the resin for Cu(II) and Pb(II) evaluated from Langmuir models were 389.9 and 403.1 mg/g, respectively. Desorption studies revealed that Cu(II) and Pb(II) can be easily removed by treating metal ion adsorbed resins with 0.1 M H2SO4 or 0.1 M HCl. The adsorption-desorption process was a reversible process, which indicates that the polyamides are promising adsorbents for heavy metal removal from aqueous medium.