Study of Adsorption Equilibrium and Kinetics of direct blue 71 by activated red mud from aqueous solutions

Some of dyes are toxic and even carcinogenic and require separation and advanced treatment of textile effluents before being discharged into conventional systems. The objective of this study was to remove the direct blue 71 dye from aqueous solutions using activated red mud. Red mud was activated by nitric acid and was used in the adsorption experiment. Direct blue 71 removal, using activated red mud was studied as a function of contact time, pH, and initial dye concentration. The adsorption isotherms were analyzed using the Langmuir and the Freundlich isotherms. Kinetics data were fitted with Pseudo-first-order and Pseudo-second-order models. The adsorption rate increases with pH decrease, contact time increase, and increase initial dye concentrations. The Freundlich isotherm (R2=0.9737) was the best-fit adsorption isotherm model for the experiment. The adsorption data, followed a pseudo-second-order model (R2=0.9902). Based on the result of the study, the use of activated red mud, as an efficient low-cost adsorbent, can be considered for (pre-) treating direct blue 71 contaminated wastewater.