Investigation of the Kinetics and Nature of Malachite Green Biosorption by Green Microalgae

In the present study, the Box-Behnken design was used to investigate the effects of the four main parameters of initial Malachite green)MG(concentration, initial solution pH, algae content, and contact time on the efficiency of dye biosorption by the green microalgae Scenedesmus quadricauda and Chlorella vulgaris. The results showed that maximum dye removal efficiencies of S. quadricauda and C. vulgaris biomasses for the biosorption of MG were 76.23 and 91.32%, respectively. Under optimum conditions, the pseudo-second order fitted with the experimental data much better than other similar models (R2>0.99). The FT-IR spectroscopy method showed that several functional groups, especially carboxyl, hydroxyl, and amine groups, present on the surface of the S. quadricauda and C. vulgaris biomasses are responsible for binding of MG ions in the biosorption process. The differences observed in the MG biosorption efficiencies of algal biomasses may be attributed to differences in interactions between the dye molecules and the algal biomasses. Finally, the findings revealed that the algal biomasses used in this study are suitable as the biomaterial for MG biosrption from wastewaters.