Sequestration of Congo red Dye from Aqueous Solution using Unmodified Almond Shell as a Local Adsorbent

Abstract

The adsorption of Congo red dye in aqueous solution using locally sourced almond shell adsorbent was investigated in this study. The effect of various factors such as contact time, initial dye concentration and adsorbent dosage on the adsorption capacity of the adsorbent was studied. The adsorption of Congo red dye was a fast kinetic process. The process was favoured at low dye concentration and medium adsorbent dosage. The results also show that maximum adsorption was obtained at a contact time of 100 minutes, an initial dye concentration of 50 mg/L and adsorbent dosage of 2 g/L. The equilibrium behaviour of the process was well described by the Langmuir isotherm equation (R2 = 0.98) indicating monolayer adsorption type. The kinetics and diffusion mechanism of the process were explained by the pseudo-second order and the int ra-particle diffusion models respectively (R2 > 0.95). The results obtained in this study shows the applicability of the almond shell adsorbent for the removal of Congo red dye from solution.

Keywords: Congo red, Adsorption, Isotherm, Contact time, Kinetic modelling