Removal of Remazol Brilliant Violet-5R dye using periwinkle shells

The purpose of this research is to obtain optimal processing conditions for the adsorption of Remazol Brilliant Violet-5R (RBV-5R) dye onto activated carbon prepared from periwinkle shells (PSAC) by chemical activation with KOH using response surface methodology. Central composite design (CCD) was used to determine the effects of three preparation variables; CO₂ activation temperature, CO₂ activation time and KOH:char impregnation ratio (IR) on two responses; percentage RBV-5R dye removal and PSAC yield. Based on the CCD, two quadratic models were developed for percentage RBV-5R dye removal and PSAC yield, respectively. The most influential factor on each experimental design response was identified from the analysis of variance (ANOVA). The optimum conditions for the adsorption of RBV-5R dye onto PSAC were CO₂ activation temperature of 811 °C, CO₂ activation time of 1.70 h and IR of 3.0, resulting in 81.28% RBV-5R dye removal and 28.18% PSAC yield. PSAC prepared under optimum conditions was mesoporous with a Brunauer–Emmett–Teller surface area of 1894 m²·g^?1, total pore volume of 1.107 cm³·g^?1 and average pore diameter of 2.32 nm. The surface morphology and functional groups of the activated carbon were respectively determined from the scanning electron microscopy and Fourier transform infrared analysis.