A novel comparative study: synthesis, characterization and thermal degradation kinetics of a terpolymer and its composite for the removal of heavy metals

Abstract

A novel comparative account for the ion-exchange and thermal decomposition of a terpolymer and its terpolymer/activated charcoal composite was performed. The terpolymer resin was synthesized involving o-toludine and semicarbazide with formaldehyde and the novel composite was prepared using terpolymer and activated charcoal. The structure and properties of the terpolymer and terpolymer/activated charcoal composite were observed by various characterization techniques such as elemental analysis, FTIR, UV–Visible, NMR (13C and 1H) and SEM. The heavy metal ion removal by the terpolymer and the composite was performed by batch separation technique for the selected divalent metal ions, e.g., Cu2+, Zn2+, Co2+, Pb2+ and Cd2+. The study was extended to various concentrations at different electrolytes, wide pH ranges and different rates. The selectivity of the order of removal of metal ion by the terpolymer was Zn2+ > Cu2+ > Co2+ > Pb2+ > Cd2+ and by the composite was Pb2+ > Cd2+ > Cu2+ > Co2+ > Zn2+. The difference in the selectivity of order of metal ions may be due to the particle size, high porosity nature, large surface area, nature of the material and metal ions. Moreover, the ion-exchange results of the terpolymer and its composite were compared with a commercially available resin. The thermal decomposition of the terpolymer and its composite was investigated by TGA, as well. Freeman–Carroll (FC) and Sharp–Wentworth (SW) methods have been adopted to determine the various kinetic and thermodynamic parameters. The decomposition reaction for terpolymer was found to be of second order but higher order was obtained for the composite. From the results, the activation energy, frequency factor and entropy change support the good thermal stability of terpolymer and its composite.