Enhanced Recovery of Palladium from an Aqueous Solution Using an Ionic Liquid–Mesoporous Silica Composite in Batch and Fixed-Column Studies

Abstract

In this modern time, precious metals hold an important place in human life. Secondary resources, such as waste, have become an essential alternative source to supplant these precious metals. Ionic liquids (ILs) have demonstrated excellent performance in recovering precious metals. Immobilizing ILs onto a solid support such as mesoporous silica simultaneously diminishes the IL drawback, enhances support adsorption capacity, and improves reusability. Thus, chemically enhanced mesostructured silica nanoparticles with trioctylodecylphosphonium chloride (P8Cl_MSN) may provide a superior adsorbent for Pd(II) from an aqueous solution. P8Cl_MSN shows a high adsorption capacity in batch and fixed-bed adsorption, 264 and 213 mg g–1, respectively. The adsorption Pd(II) fits with the Langmuir isotherm model (R2 = 0.998) and is chemisorbed onto the P8Cl_MSN. Pd(II) adsorption fits (R2 = 0.999) with the pseudo-second-order kinetic model. The continuous adsorption of Pd(II) fits (R2 = ∼0.99) with the Thomas and Yoon–Nelson model. Pd(II) desorption (98%) is achieved using CS(NH2)2 in 100 min, and P8Cl_MSN also shows excellent reusability performance and selectivity.