Application of Castor plant (Ricinus communis. L) as a green sorbent for removing cationic dyes from textile effluents.

Abstract

The present study reports the removal of cationic dyes from water using Castor plant byproducts (castor seed shell (CC), castor seed shell envelope (CE), and castor leaves (CF)) as low-cost and ecofriendly materials. The different parts of the castor plant were characterized using various techniques such as FTIR, X-Ray diffraction, SEM and EDX analysis. Dye adsorption experiments were conducted in a batch reactor to study the kinetics, thermodynamics, and equilibrium of the adsorption process. The adsorption was strongly described by Langmuir isotherm, and followed the pseudo second-order-kinetic model. The thermodynamic parameters indicate that the adsorption in this case is an exothermic, spontaneous and physical process. The results showed that all the castor plant materials had a much higher uptake capacity for the Toluidine Blue (TB) dye compared to Yellow X-GL 200% (YX-GL) one, reaching maximum adsorption capacities above 1107.69 mg.g^-1 for BT and 109.02 mg.g^-1 for YX-GL. The desorption study showed that different Castor plant based-adsorbents could be reused multiple times (at last 6 times) without losing their adsorption performance. Overall, the experimental outcomes demonstrated that the Castor plant byproducts may be considered as efficient and reusable alternative adsorbents for the treatment of dye-contaminated effluents.