Optimization of Cr(VI) removal onto biosorbent eggshell membrane: experimental & theoretical approaches

The discharge of heavy metal pollutants, particularly Cr(VI) ions emerging out from the industries into water, has become a serious concern. In the present study, feasibility of eggshell membrane has been tested for the removal of Cr(VI) ions from its aqueous solutions. The membrane was separated from the eggshells, dried at 40°C for about 3 h and then crushed into powder. The characterization of powdered eggshell membrane was carried out using scanning electron microscopy, FTIR, and XRF analysis. Batch adsorption experiments have been performed for the investigation of the ability of powdered egg membrane to remove Cr(VI) ions from its solution. The effect of pH, Cr(VI) ion concentration, sorbent dosage, contact time, and temperature has been evaluated. The theoretical treatment from the experimentally gathered data has been carried out to measure the effect of these variables using central composite design (CCD). The results of the CCD show that the maximum removal (81.47%) was achieved at temperature 20°C, pH 3.54, Cr(VI) ion concentration 5.0 mg/L, time 117.52 min, and dosage 3.78 g.