Enhancement of methylene blue adsorption onto activated carbon prepared from Date Press Cake by low frequency ultrasound

This study was aimed to evaluate the adsorption of methylene blue onto activated carbon prepared from Date Press Cake (AC-DPC) in the absence (stirring) and presence of low frequency ultrasound (no stirring). Date Press Cake (DPC) was converted into activated carbon (BET surface area of 2632.5 m(2) g(-1)) using solid KOH. Batch adsorption experiments illustrated that the adsorption of MB onto AC-DPC was more favored at alkaline conditions. Kinetics analysis showed that the adsorption of MB onto AC-DPC was controlled by film diffusion in both agitation methods. The values of adsorption rate constants in kinetic models were increased by applying low frequency ultrasound to the adsorption system. Such acceleration effect was reflected in equilibrium contact times, which were 180 and 20 min in the absence and presence of ultrasound, respectively. The experimental equilibrium data for both agitation methods were best fitted with Redlich-Peterson isotherm model, indicating chemisorption nature of MB adsorption onto AC-DPC. The maximum monolayer adsorption capacity of MB on AC-DPC was found to be increased from 546.8 mg g(-1) (stirring) to 613.8 mg g(-1) in the presence of low frequency ultrasound. Therefore, low frequency ultrasound increased both the rate and amount of MB adsorption onto ACDPC. Overall, KOH-activated carbon prepared from Date Press Cake efficiently adsorbed MB from aqueous solutions. Moreover, the equilibrium and kinetics of MB adsorption onto AC-DPC could be improved in the presence of low frequency ultrasound. (C) 2018 Published by Elsevier B.V.