Equilibrium and kinetics studies for the adsorption of Cr (VI) and rhodamine B from aqueous solution by almond shell

In general, adsorption involves the accumulation of molecules from a solvent onto the exterior and interior surfaces of an adsorbent. This surface phenomenon is a manifestation of complicated interactions among the three components involved, the adsorbent, the adsorbate and the solvent. Normally, the affinity between the adsorbent and the adsorbate is the main interaction force controlling adsorption. However, the adsorbate - solvent affinity can also play a significant role in adsorption.An inexpensive adsorption method has been developed for the removal of Cr(VI) and rhodamine B (RhB) dye from aqueous solution. Effects of contact time, particle size and adsorbent dose were investigated. The data evaluated for compliance with the Langmuir, Freundlich and Temkin isotherm models. Adsorption trends for both chromium (R2 0.969) and RhB (R2 0.933) followed Freundlich isotherm. Two widely used models are the Lagergren first-order kinetic model and pseudo second-order model which assume the driving force of adsorption is the difference between the equilibrium concentration qe and the adsorbate uptake q. The kinetic data were found to follow the pseudo-second-order kinetic model.

Keywords:

Biosorption , Cr (VI) , rhodamine B , Isotherm , Kinetic model