Application of Taguchi design approach to parametric optimization of adsorption of crystal violet dye by activated carbon from poultry litter

Abstract

The present study focuses on the use of agricultural waste to achieve a cleaner environment by preparing an activated carbon from poultry litter for the removal of a cationic dye (crystal violet, CV) from an aqueous solution. The prepared poultry litter activated carbon (PLAC) was characterized by Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Taguchi design approach was applied to establish the optimum condition for the CV dye removal by PLAC. The PLAC with a graphitic carbon structure demonstrated a high specific surface area (148.05 m2/g) to enhance the adsorption of CV. Among the studied process variables, adsorption efficiency was mainly affected by initial concentration, pH and adsorbent dosage. At the optimum initial CV concentration of 50 mg/L, solution pH of 10, adsorbent dosage of 2.5 g/L and contact time of 45 min, the removal efficiency was 92.03%. Based on ANOVA results, pH showed the largest contribution percentage of 76.95%, indicating that it had the most significant effect on removal efficiency. The experimental results were analyzed by Langmuir, Freundlich and Temkin models of adsorption. The Freundlich isotherm gave the best fit with the experimental data, indicating a multilayer and heterogeneous adsorption system with a maximum adsorption capacity of 70.32 mg/g. Kinetic data obtained at optimum initial concentration were evaluated using pseudo-first-order and pseudo-second-order kinetic models. The experimental data fitted very well the pseudo-second-order model, which indicated the dominance of chemisorption mechanism.