Groundnut shell chemically treated with KOH to prepare inexpensive activated carbon: Methylene blue adsorption and equilibrium isotherm studies

Groundnut shell activated carbon (GNSAC) is made from groundnut shells using potassium hydroxide (KOH) at 600 °C in a nitrogen atmosphere. The properties of the products were examined using FT-IR, XRD, SEM with EDS, and BET analysis. The activating temperature of 600 °C and the impregnation ratio of 1:1 were observed as optimum for achieving the highest surface area (412 m2/g). The adsorption efficiency of optimized GNSAC (1:1) was evaluated using a methylene blue (MB) dye solution. The effects of contact time, pH, adsorbent dose, and beginning dye concentration on the removal efficiency of MB were investigated among the GNS/KOH ratios of a 1:1 sample used as the adsorbent. Additionally, the Langmuir and Freundlich adsorption models were used to support the adsorption isotherms. According to the adsorption data at these ideal conditions, GNSAC is capable of absorbing 83.33 mg/g of dye at equilibrium as demonstrated by the Langmuir isotherm. This result demonstrates that GNSAC is a potentially useful material for wastewater treatment.