Comparative studies on adsorption of methylene blue by sawdust and walnut shells carbon coated with ZnO

Abstract

The adsorption characteristics of activated carbon prepared from walnut shells and sawdust were studied by the batch equilibrium techniques. The results showed that the % of dye removed decreases as the initial concentration of dye increases. It further showed that the % of MB removed by SDZ and WNSZ fluctuates as a result of desorption occurring along side adsorption. The experimental data fitted into both the Langmuir and Freundlich isotherm models as shown by the correlation coefficients values in the range of 0.54 to 0.99. The monolayer adsorption capacity was in the order CPAC>SDZ>WNSZ. Though CPAC shows a superior performance compared to SDZ and WNSZ, the values for the adsorption capacities and efficiencies observed for both SDZ and WNSZ are high and could be used as alternative adsorbents to the commercially available activated carbon for the removal of dyes.