2.4.2 Methylene blue (Batch experiments)
For batch studies on methylene blue (MB) adsorption, 100 mL of MB solutions with initial concentrations of 50-200 mg/L were placed in Erlenmeyer flasks to which an equal mass of 0.1 g of the activated carbon of 40 mesh size was added and kept in a shaker at 30°C for 24 h to reach equilibrium. All samples were filtered prior to analysis in order to minimize interference of the carbon particles with the analysis. Each experiment was carried out in triplicate under identical conditions. The concentrations of MB in the supernatant solutions before and after adsorption were determined using a CARY Bio-300 UV-Visible Spectrophotometer (Varion) at 668 nm. The amount of adsorption at equilibrium, qe (mg/g) was calculated by the formula:
qe= (Co-Ce)V/ W
Where, C0 and Ce (mg/L) are the liquid-phase concentrations of the dye at initial and equilibrium state; V is the volume of the solution (L) and W is the mass of dry adsorbent used (g).