New ion-imprinted polymer-functionalized mesoporous SBA-15 for selective separation and preconcentration of Cr(III) ions: modeling and optimization

A new Cr(III) ion-imprinted polymer (Cr(III)-IIP) was prepared by functionalizing the surface of an SBA-15 support with dithizone (DZ) indicator followed by an imprinting polymerization method. The Cr(III)-IIP was characterized using FTIR, EDS and SEM techniques. Using dispersive solid phase extraction coupled with flame atomic absorption spectrometry (DSPE-FAAS), the ultrasound-assisted adsorption properties of the Cr(III)-IIP were investigated and compared with those of a non-imprinted polymer (NIP), using the batch method. Central composite design under response surface methodology was used for the evaluation of the effect of variables, individually, as well as their possible interaction effects, on the adsorption process. Variables such as sonication time, Cr(III)-IIP mass, concentration of Cr(III) and pH were involved in this study. Under optimum experimental conditions, this DSPE-FAAS method exhibited a linear range of 2-950 mu g L-1 for the Cr(III) ion concentration with a detection limit of 0.06 mu g L-1. The relative standard deviation for the analyte was found to be lower than 2.44%. The selectivity of the method was tested by analyzing the interference of ions such as Pb2+, Co2+, Ag+, Zn2+, Ni2+ and Fe2+, and the method showed good selectivity. The method was successfully applied to the separation and preconcentration of Cr(III) ions from tap, river and spring water. The IIP adsorption capacity was found to be 131.4 mg g(-1). The enrichment and preconcentration factors were found to be 97 and 147.7, respectively.