ADSORPTIVE REMOVAL OF METHYLENE BLUE FROM SYNTHETIC WASTEWATER USING DATE PALM SEEDS, GOETHITE AND THEIR COMPOSITE

Abstract

The adsorption of Methylene Blue (MB) onto Raw Date-palm Seeds (RDS), Thermally Activated Carbon (TAC), Chemically Activated Carbon (CAC), Goethite (GT) and their Composite (COM) were studied using batch equilibrium technique. Variations of sorptive properties such as initial solution concentration, pH, adsorbent dosage, contact time and temperature had a remarkable influence on the adsorption processes. The data fitted well tested isotherm models in the order; Langmuir (R2 = 0.942 and 0.963) > Freundlich (0.886 and 0.948) > Temkin (0.869 and 0.83) for GT and COM respectively. That of CAC and TAC was best described by Freundlich and Langmuir models respectively while RDS showed very poor fittings. Pseudo-second order and film diffusion models best described the adsorption kinetics. The adsorption was feasible, spontaneous (∆G < 0) and exothermic (except MB-CAC with ∆H being positive). The combined results of isotherm, kinetics and thermodynamic studies suggested a combined chemisorptions and physisorptions processes. Also, the kinetic modeling suggested that intra-particle and film diffusions occurred simultaneously and/or in combination with other processes in the mechanism of adsorption.