Removal of copper ions from aqueous solutions using poly(vinylbenzyl chloride)

Abstract

Poly (vinyl benzyl chloride) (PVBC) was synthesized through Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerisation technique utilizing monomer, vinylbenzyl chloride (VBC), 4-cyano-4 (phenyl-carbonothioylthio pentanoic acid) (CPADB) as RAFT agent and 4,4'-Azobis (4-cyanopentanoic acid) (ACPA) as initiator. The aim of this study is to obtain PVBC polymer with higher conversion rate and higher molecular weight polymer and to test on its ability to remove copper ions from aqueous solution. In this study, the time and temperature of RAFT polymerisation of PVBC was varied while the mole ratio VBC: CPADB: ACPA of polymerisation reaction is kept constant. PVBC was successfully synthesized when reacted for 24 hours at 80°C. The PVBC was characterized by Proton Nuclear Magnetic Resonance spectroscopy (1H NMR) and Attenuated Total Reflection (ATR-FTIR). The highest monomer conversion was 57.7 % at 80°C for 24 hours. To explore the ability of the PVBC, adsorption study was carried out using Cu (II) solution. The PVBC was evaluated for removal of Cu (II) ions from aqueous solution. Important adsorption parameters such as adsorbate concentration, adsorption dosage and contact time were studied. The maximum Cu (II) adsorption ability (Qmax) of PVBC was 263.15 mg/g with copper removal rate 95 % under the optimum conditions of initial concentration (160 ppm), adsorbent dosage (14mg) and contact time (3 hours). The experimental data fitted better into Langmuir adsorption isotherm model than Freundlich model and kinetics studies were correlated with pseudo-second-order kinetic model. The polymers adsorption ability was over than 90% level after five cycles of adsorption but the total adsorption ability of PVBC for Cu (II) ions started to decrease after other five cycles from 80% to 54%. In view of the outcomes acquired, PVBC can be an effective and potential adsorbent for removing Cu (II) ions from an aqueous solution. The adsorption study showed that the PVBC has affinity towards Cu (II) ions. The prepared of PVBC proved to be potentially good for applications in wastewater treatment.