Adsorptive removal of Ni²⁺ and Cd²⁺ by polymethacrylamide and polyvinylamine derivatives from water

Abstract

Heavy metals are environmental toxins entering in the food chain through drinking water causing serious health hazards. In the present work, surface of polymethyl methacrylate and polyvinyl chloride was functionalized with amine groups using 1,2-ethylenediamine and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and elemental analysis. The resulting polymers polymethacrylamide derivative of 1,2-ethylenediamine (PMAm) and polyvinylamine derivative of 1,2-ethylenediamine (PVAm) were tested for the adsorption of Ni²⁺ and Cd²⁺ ions from water. Effect of various physicochemical parameters such as pH, adsorbent dose, contact time, initial Ni²⁺ and Cd²⁺ ion concentration, and temperature on adsorption of Ni²⁺ and Cd²⁺ ion was investigated. Langmuir and Freundlich isotherm models were used to analyze equilibrium data of adsorption. Monolayer adsorption capacity of PMAm-Ni²⁺, PMAm-Cd²⁺, PVAm-Ni²⁺ and PVAm-Cd²⁺ systems was found to be 7.87 mg/g, 10.57 mg/g, 23.92 mg/g, and 31.44 mg/g, respectively. Kinetic studies were performed using pseudo-first-order, pseudo-second-order kinetic models, and intraparticle diffusion method. The spontaneity and nature of adsorption process were determined by thermodynamic parameters, such as change in Gibb’s free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°).

Keywords:

• Adsorption
• Nickel
• Cadmium
• Isotherm
• Kinetics
• Thermodynamics

Acknowledgments

Authors are thankful to the SAIF-CDRI Lucknow for elemental analysis; Dr Dinesh Deva of Nanoscience, IIT Kanpur for recording SEM, and Council of Scientific and Industrial Research (CSIR), New Delhi, India, for the financial support.