Synthesis, characterization, and heavy metal ion adsorption studies of polyamides, polythioamides having pendent chlorobenzylidine rings



Aromatic polyamides and polythioamides with pendent chlorobenzylidine rings were synthesized through direct polycondenzation of 2-(p-chlorobenzalimino) terephthalic acid with the diamines 4,4′-oxidianiline (1a), 4,4′-methylenediamide (1b), 4,4′-diaminodiphenyl sulfone (1c), and thioamines 4,4′-(bisthiourea) diphenyl ether (3a), 4,4′-(bisthiourea) diphenyl methane (3b), 4,4′-(bisthiourea) diphenyl sulfone (3c), respectively, in DMF using P(OPh)3/pyridine. The polymers were precipitated using water as nonsolvent. FTIR and 1H-NMR spectroscopic analysis was used to characterize the monomers and polymers. Representative polyamides and polythioamides were used for the removal of heavy metal ions such as Pb(II), Cd(II), Cu(II), and Cr(III) from aqueous solutions. The effects of pH, contact time, and initial concentration on the uptake of metal ions have been investigated. The adsorption capacities under competitive conditions were in the order Pb (II) > Cu (II) > Cr (III) > Cd (II). The adsorbed ions were eluted by treatment with 2N HCl, and the activities of the polymers are retained after fourth regeneration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011