Polyacrylamide-Grafted Actinidia deliciosa peels powder (PGADP) for the sequestration of crystal violet dye: isotherms, kinetics and thermodynamic studies

Abstract

Herein, a novel and eco-friendly low-cost adsorbent polyacrylamide-grafted Actinidia deliciosa (Kiwi fruit) peels powder (PGADP) was synthesized and utilized as a potential adsorbent for the sequestration of crystal violet (CV) dye from aqueous solution. The material was characterized by various analytical techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption process was carried out in a batch process with different concentrations, adsorbent doses, pH, contact time and temperatures. The maximum adsorption of CV dye from aqueous solution was observed at pH 7.3, contact time 180 min and initial dye concentration 20 mgL ⁻¹. The equilibrium data were tested by applying various isotherms models such as Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D-R), and the results showed that Langmuir was found to be the best fitted model based on the highest correlation coefficient ( R ²). Kinetic data showed that pseudo-second order model was best obeyed over wide range of concentrations. In thermodynamic study, positive value of ∆H ^o and negative value of Δ G° confirm endothermic and spontaneous nature of adsorption process with increased randomness at solid-solution interface. Desorption of CV dye was performed successfully using 1 M acetic acid with excellent regenerating capacity that lasts up to fourth cycle. Therefore, PGADP can be used effectively and economically for removal of CV dye from aqueous solution and industrial waste water.