CRYSTAL VIOLET DYE ADSORPTION BY A BIOSORBENT MIXTURE OBTAINED FROM Salvinia biloba AND Pistia stratiotes

The macrophytes Salvinia biloba and Pistia stratiotes were used to prepare a biosorbent capable of removing the crystal violet (CV) dye present in an aqueous solution. The biosorbent preparation process included washing, drying and grinding the macrophytes, and the final biosorbent comprised a mixture of the two macrophytes in a 1:1 ratio. The biosorbent was characterised using infrared (IR) spectroscopy and scanning electron microscopy (SEM). The results of SEM showed that the biosorbent had a structure that promoted adsorption, whereas IR analysis showed the presence of acid functional groups. An investigation of adsorption potential showed that the biosorbent efficiently removed the CV dye from aqueous solutions, with a maximum observed adsorption capacity of 384 mg g−1. The Freundlich and Langmuir models were applied to the data; the adsorption was adjusted in both isotherm models, and the adsorption capacity was superior at 25ºC. Tests of the samples revealed relatively fast kinetics (with equilibrium reached in approximately 150 min) that followed the pseudo-second order-rate equation. This study showed that S. biloba and P. stratiotes can be used together to increase the capacity for the adsorption of CV dye; these organic materials are low cost and abundant in nature.