4-aminosalicyclic acid, urea, and formaldehyde copolymer resin non-isothermal degradation studies and ion-exchange properties

Abstract

Copolymer resin 4-ASAUF was synthesized by the condensation of 4-aminosalicylic acid (4-ASA) and urea (U) with formaldehyde (F) in the presence of 2 M HCl as catalyst with 2 : 1 : 4 molar ratios of reacting monomers. The structure of the resin was characterized by various spectral techniques like infra-red (FTIR) and nuclear magnetic resonance (1H and 13C NMR) spectroscopy. The empirical formula and empirical weight of the resin were determined by elemental analysis. The morphological feature of the 4-ASAUF copolymer resin was established by Scanning Electron Microscopy (SEM). Thermal study of the resin was carried out to determine its mode of decomposition and relative thermal stability. The Freeman-Carroll, Sharp-Wentworth, Friedman and Change methods have been used in the present investigation to calculate thermal activation energy (Ea), order of reaction (n) and frequency factor (z). The chelating ion-exchange property of this copolymer was studied for eight metal ions viz. FeIII, CuII, NiII, CoII, HgII, ZnII, CdII and PbII ions by using batch equilibrium method. The chelating ion-exchange study was carried out over a wide pH range at different time intervals using different electrolyte of various ionic strengths.