Methylene blue removal using grape leaves waste: optimization and modeling

Abstract

Abstract The present study focuses on the preparation of activated carbon (AC) from grape leaves as a low cost, non-toxic, efficient and available adsorbent for the removal of methylene blue (MB) from aqueous solution. The experimental design and data modeling have been carried out using response surface methodology (RSM) through DoE software version 8.0.0. The effect of independent variables including initial dye concentration (100–500 mg/L), pH (3–11), contact time (10–90 min) and adsorbent dosage (0.25–12.25 g/L) on dye removal was determined using the response surface methodology (RSM). The results of analysis of variance (ANOVA) displayed high R 2 value of 0.91% for dye removal that shows the developed model has acceptable accuracy. The highest removal efficiency of MB (97.4%) was obtained at optimum condition (pH: 11, adsorbent dosage 12.5 g/L, MB concentration 100 mg/L and contact time 90 min). The results indicated that the initial dye concentration and adsorbent dosage play an important role in increasing the adsorbent efficiency for adsorption of MB. The equilibrium data onto the adsorption of MB were measured using Langmuir and Freundlich, isotherm models. The experimental data obtained follow the Langmuir model (R 2 = 0.88). In addition, the second-order kinetic model is more consistent with the adsorption data.

Keywords

• Activated carbon
• Grape leaves
• Adsorbent
• Modeling
• Methylene blue