Grafting of coconut coir adsorbent with ionic liquid and its effect on the adsorption of reactive dye, drimarene red

Abstract

Dye-loaded wastewater is a threatening environmental problem that has subsequently received enormous scientific attention especially in the form of adsorption studies. Considering the adsorption technique, numerous ideas have been presented for the modification of the adsorbents to enhance their adsorption efficiency. In the present study, a new modification process has been proposed in the form of grafting of the adsorbent with an ionic liquid and its effect on adsorption efficiency has been investigated. The adsorbent used in the study is coconut coir to remove Drimarene Red dye from the water after grafting with the ionic liquid, 1-hexyl-3-methylimidazolium hexaflu-orophosphate (HMI)[PF6 ]. The results are highly encouraging and have shown that grafting greatly enhances the adsorbent efficiency of coconut coir. The percentage removal efficiency increased from 67.8% to 96.1% as well as adsorption capacity which increased from 6.78 to a 9.61 mg g–1. The kinetic studies have shown that adsorption follows the rapid kinetics and equilibrium is achieved within 6 min with a percentage removal of around 96.1%. The process follows pseudo-second-order kinetics and the data is highly compatible with the Langmuir isotherm model. The scanning electron microscopy analysis and IR spectroscopy have confirmed the process of grafting. The encouraging result of the study presents a novel technique of the modification of the adsorption for the enhancement of adsorption efficiency.