Response surface methodological approach for the optimization of adsorption process in the removal of Cr(VI) ions by Cu2(OH)2CO3 nanoparticles

Cu2(OH)2CO3 nanoparticles were synthesized and characterized by XRD, TEM, SEM and ATR-FTIR. SEM suggested the porous nature of nanoparticles. BET surface area of nanoparticles was measured to be 87 m2 g−1. Cu2(OH)2CO3 nanoparticles were used as adsorbent for the removal of Cr(VI) ions from aqueous solutions and wastewater of the printing press. The central composite design (CCD) of the response surface methodology was employed to optimize important adsorption parameters viz. initial Cr(VI) concentration, pH and dose. Analysis of variance (ANOVA) of the quadratic model suggested that experimental data were excellently fitted to the quadratic model. Optimum conditions for approximately 99% removal of Cr(VI) from synthetic wastewater were determined to be pH 6.5, initial concentration of 550 mg/L, adsorbent dose 0.69 g. The kinetic data for Cr(VI) adsorption were best fitted to the pseudo second order model. The Langmuir adsorption capacity of the adsorbent was determined as 87.72 mg/g. Thermodynamic analysis revealed that the adsorption process was spontaneous and endothermic. Desorption study confirms its reusability up to four adsorption–desorption cycles. Cu2(OH)2CO3 nanoparticles also showed efficient removal in presence of anions like SO42−, PO43−, NO32− and Cl−. Findings of the present study suggest that Cu2(OH)2CO3 is a suitable adsorbent material for the removal of Cr(VI) from aqueous solutions and wastewater.