Novel Calix[4]arene Network resin for Cr(VI) ions remediation: A response surface approach

Abstract

Novel Calix[4]arene Netwok (NCN) resin has been synthesized using Amberlite XAD-2 as the starting material. Hydroxyl groups have been introduced onto the para position of alkylated phenyl ring of Amberlite XAD-2 followed by the condensation to NCN by reacting it with formaldehyde. The NCN resin has been used for the remediation of Cr(VI) contaminated water using factorial design approach. A face-centered Draper-Lin composite design predicted ∼100% removal efficiency at optimum variables (the initial concentration of Cr(VI) ion 10 mg/l sorbent dose 200 mg, agitation time 136 min and pH 2). The accuracy and the fitting of the model were evaluated by ANOVA and R2 (0.9992) values. The 99.5% removal efficiency has been achieved experimentally at the optimum values of the variables. The Langmuir and D-R isotherm models were applicable to the sorption data with the value of RL and the sorption free energy 0.0057-0.1 and 7.93 kJ/mol respectively, suggesting favorable and physical/ion-exchange nature of the sorption. The calculated sorption capacity was 176.1±2.4 mg/g. The recycling studies of NCN resin showed that the multiple use of resin is feasible. Effect of concomitants has also been studies and proposed method was applied successfully for removal (98.7%) of Cr (VI) from electroplating wastewater.