Optimization and batch studies on adsorption of Methylene blue dye using pomegranate fruit peel based adsorbent

Abstract

Abstract Pomegranate fruit peel activated carbon (PFPAC) was prepared using potassium hydroxide impregnation and carbon (IV) oxide gasification methods for the remediation of Methylene blue (MB) from aqueous solution. The design of experiment for the optimization of variables for preparing activated carbon sourced from pomegranate fruit peel was carried out using response surface methodology (RSM). The adsorbent was characterized using BET, SEM, FTIR, and elemental analysis respectively. The BET analysis showed an improved surface area from raw PFP (1.01 m2/g) to PFPAC (845.96 m2/g). The optimum conditions for the adsorption of MB dye are 375 W, 0.9, and 4.5 min for radiation power, impregnation ratio, and activation time respectively. These resulted in high percentage of MB dye removal and PFPAC yield of 83.4% and 30.8% respectively. For batch equilibrium studies, the adsorption of MB dye onto the optimized PFPAC showed a strong dependence on the temperature, contact time, and initial MB dye concentration. Kinetic studies revealed rapid MB dye uptake at the initial stages of 0 – 3 h and attained equilibrium at 6 h for initial concentrations of 25 – 300 mg/L. Langmuir maximum monolayer adsorption capacities, q o ( max ) , at temperatures of 303, 318, and 333 K are 250.00, 239.05, and 235.58 mg/g respectively, thus suggesting a favourable adsorption at low temperature. Modeling of the adsorption data using three kinetic models, revealed that pseudo first order (PFO) model best explained the adsorption process of MB dye onto PFPAC indicating a physisorption process. Chemically activated PFPAC was found to be valuable and effective for sequestrating MB dye from the aqueous solutions. Procedure Experimental design (central composite design)