Adsorption of Direct Blend Yellow D-3RNL onto bamboo-base activated carbon: optimization, kinetics, and isotherm

Abstract

Adsorption of Direct Blend Yellow D-3RNL in aqueous solution by activated carbons prepared from Moso timber bamboo stem residues was optimized by using central composite design matrix and response surface methodology. A maximum dye removal from the experimental validation reached 92.1% under the optimum conditions (initial dye concentration 20 mg L-1, pH 2, bamboo-based activated carbon dosage 20 g L-1, temperature 50°C, and time of adsorption 20 h) with the relative standard deviation 5.37%. The high R2 value (0.9487) for the second-order model obtained from the analysis of variance (ANOVA) indicated that the experimental data fitted well with the predicted data. The adsorption followed the nonlinear model of pseudo-second-order reaction and agreed well with Freundlich judged by the levels of Akaike Information Criterion and Akaike weight. Furthermore, the thermodynamics analysis indicated that the adsorption was a spontaneous, endothermic, entropy-increasing, and chemisorption process.