Adsorption of methylene blue dye onto modified activated carbon produced from groundnut shells

Abstract

In this research work, groundnut shells agricultural byproducts were utilized for the production of modified groundnut shell based activated carbon (MGSAC) through the use of phosphoric acid and ethylene-diamine tetraacetic acid disodium salt (Na2EDTA) as an activating agent and a modifier, respectively. A three factor, two-level full factorial design (FFD) was employed for the exploratory design of experiments (DoE). The independent process variables are temperature, activation time, and activating agent concentration for the production of MGSAC in a muffle furnace. The product yield and methylene blue (MB) dye adsorption were considered as the performance indicators for the process. Regression analysis was conducted to examine the influence of process variables on the responses of the process parameters. From the analysis, it was found that the activation temperature has the most significant effects on the MGSAC product yield and the activation time for the adsorption of MB dye. The results obtained showed that the best operating conditions for production of MGSAC were carbonization temperature of 450°C, activation time of 30 min and activating agent concentration of (35 mmol Na2EDTA; 50% H3PO4) which resulted in the product yield of 55.5% MGSAC, and 99.6% MB dye adsorption. It was also observed that experimental values obtained were in good agreement with the values predicted by the model. Hence, the two-level FFD DoE technique demonstrated worthwhile features in disclosing the dominant factors that affect the production of modified groundnut shell based activated carbon. The products appear to be promising adsorbents for the adsorption of cationic MB dye from wastewaters.