5G blue textile dye biosorption using eichhornia crassipes root: characterization and kinetic and equilibrium essays

Abstract

The textile industry has prominence in the national scenario, however, it generates a high volume of effluents, which contain dyes, which even in low concentrations can cause problems to the ecosystem and human health. Adsorption is a technique for wastewater treatment, which allows the use of effective and low-cost materials, as known “biosorbentsâ€, with the Eichhornia crassipes root being reported as an effective biosorbent. Thus, the present work aimed to use the water hyacinth root to remove the 5G reactive blue dye, commonly used in the dyeing processes of the textile industries. The biosorbent was evaluated for its morphology and subjected to adsorption tests, to determine the ideal conditions of pH, temperature, and agitation speed, also to obtaining the kinetic and equilibrium curves. In the SEM characterization, a material with a fibrous surface was verified. The optimized operational conditions that favor adsorption were: pH 2, 40 ° C and 70 rpm, with 99% removal. In the kinetic tests, it was found that the equilibrium time was reached after 210 min, with a better fit of the pseudo-second order model. The isotherm demonstrated an H2 profile, and the Freundlich and Temkin models best described the equilibrium behavior. The maximum adsorption capacity or monolayer estimated by the Langmuir model was 41.3 mg g-1. In general, water hyacinth showed adsorption capacity similar to other agro-industrial wastes reported in the literature and can be made viable for use as a biosorbent.