Synthesis of Ionic Liquid Enhanced Natural Adsorbent via Impregnation for the Recovery of Precious Metals from Aqueous Solutions

Precious metals, such as platinum, palladium, and rhodium plays a significant role in our modern life. Due to dwindling of natural resources, secondary resources, such as waste hold a significant importance as alternative resource for these precious metals. Ionic liquid and natural adsorbent such as chitosan have been explored to extract various types of metals from aqueous solution. Thus, chemically enhancing the chitosan by using ionic liquid could provide a superior adsorbent for precious metals recovery. Cyphos IL101 was impregnated onto chitosan (Cy101/chitosan) and was used in the adsorption of Pd(II) from aqueous solution. The adsorbent was characterized by using SEM, EDX, XRD, and FTIR. Various parameters, such as pH, adsorbent dosage, kinetic, thermodynamic and isothermal were carefully studied. The impregnation process did not significantly alter the physicochemical characteristic of chitosan. However, the results showed that Cy101/chitosan exhibit a fast reaction kinetic and low thermodynamic barrier for the adsorption of Pd(II). According to the results, Pd(II) was chemically adsorbed onto Cy101/chitosan and the reaction follows pseudo second-order kinetic model. The equilibrium data fitted well with the Langmuir isotherm model with maximum adsorption capacity of 284.8 mg g^-1. Thermodynamic parameter showed that the adsorption was spontaneous and exothermic in nature. This study highlighted a simple process of enhancing adsorption capacity of natural adsorbent, such as chitosan by using a phosphonium-based ionic liquid. The adsorbent performed excellently in the recovery of precious metals, providing an insight into a sustainable way to acquire precious metals.To format your abstract, use the Microsoft Word template style.