Adsorption Kinetics of Blue 5G Dye from Aqueous Solution on Dead Floating Aquatic Macrophyte: Effect of pH, Temperature, and Pretreatment

Abstract

The textile industry is known to generate large quantities of effluents contaminated with dyes that are not fixed to the fibers during the dyeing process. The available technologies to remove these dyes from the wastewater are expensive and ineffective. Within this context, low-cost, easy-maintenance technologies for the removal of dyes have been studied, such as adsorption on aquatic macrophytes. Thus, the macrophyte Salvinia sp., raw or pretreated with NaOH or H3PO4, was used as biosorbent of Blue 5G reactive dye. The study showed that pH and temperature affect the dye removal capacity. The analysis of the infrared spectrum (FTIR) showed that chemical treatment of the Salvinia sp. modified the biomass surface and affected dye adsorption capacity. The pseudo-second-order kinetic model satisfactorily described the experimental data for raw and NaOH-pretreated biomass, and the pseudo-first-order model was more appropriate to describe the experimental data obtained with H3PO4-pretreated biomass. The highest capacity of Blue 5G dye removal was obtained with raw biomass, at 333 K and pH 1.0, with 98.35 % adsorption.