Kinetic and thermodynamic studies of malachite green adsorption on alumina

The present study concerns the optimization of the parameters involved in the adsorption process of malachite green (mg) onto commercial alumina (al2o3). the effect of temperature,ph,contact time (ta) and initial concentration (c0) of adsorbate on adsorbed amount was studied. it has been found that the retention rate of mg,by a mass m = 0.1 g of al2o3,is optimal by adopting the following experimental parameters: ph = 7,c0 = 8×10-5 m and ta = 2 h. the adsorption capacities (qt),obtained at different adsorption temperatures (25,30 and 40 °c),are respectively equal to 13.49,13.61 and 13.64 mg/g. the modelling of the experimental results showed that the adsorption kinetics of mg on al2o3 follow pseudo-second-order kinetics at the temperatures studied,while the langmuir model describes the adsorption isotherms.the thermodynamic study showed that the adsorption reaction of mg on al2o3 is spontaneous (δg° < 0) and endothermic (δh° > 0). the characterization of surface of alumina by ftir,xrd and dta/tga,before and after its contact with mg,made it possible to elucidate the nature of the interactions between mg andal2o3. © 2017,university of mohammed premier oujda morocco.