Thiopropyl-containing ionic liquid based periodic mesoporous organosilica as a novel and efficient adsorbent for the removal of Hg(II) and Pb(II) ions from aqueous solutions

In the present study, a novel thiol-functionalized ionic liquid based periodic mesoporous organosilica (PMO-IL-SH) is prepared and characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and energy dispersive X-ray analysis (EDAX). The PMO-IL-SH nanomaterial was successfully used for the removal of Hg(II) and Pb(II) ions from aqueous solution. A series of batch adsorption experiments was conducted to study the effects of pH, contact time, adsorbent dose, initial dye concentration, and temperature. Isotherm, kinetics and thermodynamics models were used to study the adsorption behavior. Adsorption isotherms of Hg(II) and Pb(II) ions obeyed the Langmuir equation indicating monolayer sorption. Adsorption kinetics based on a pseudo-secondorder rate equation showed that the rate limiting step involves a chemical reaction. Based on thermodynamics data, Delta G degrees, Delta H degrees and Delta S degrees, it was concluded that the adsorption of Hg(II) and Pb(II) ions on the PMO-IL-SH is endothermic, spontaneous and feasible in nature.