Bentonite-Polysorbate 80 for Removal CI Direct Blue 1 and CI Direct Yellow 4

The non-ionic surfactant Polysorbate-80, often known as Tween-80, was employed to increase the adsorption capacity of natural bentonite. The procedure of modifying bentonite was conducted using microwave radiation. The intercalation of polysorbate-80 increased the basal spacing of bentonite from 1.54 to 1.66 nm. The bentonite's BET surface area is 72.6 m²/g, accompanied by a total pore volume of 0.61 cm³/g. In contrast, the BET surface area of bentonite-polysorbate 80 is determined to be 84.2 m²/g, with a total pore volume of 0.72 cm³/g. The adsorption kinetics of direct blue-1 (DB-1) and direct yellow-4 (DY-4) on bentonite and bentonite-polysorbate 80 may be accurately described by the pseudo-second-order model. Furthermore, the adsorption isotherms data for both dyes can be best fitted using the Langmuir equation. A proposed modification of the extended Langmuir model was suggested as a means to enhance the efficacy of this model in correlating binary adsorption data. Incorporating the competition parameter into the affinity coefficient parameter of the Langmuir equation allows for the representation of the binary adsorption of DB-1 and DY-4.