New adsorbent material based on nitrothiophene-functionalized silica particles for aqueous heavy metals removal

Research of efficient materials is a well-established technology. In this work, a novel and excellent host, with sulfur donor atom, for heavy metals adsorption was synthesized by chemical immobilization of nitrothiophene receptor onto silica particles. The new adsorbent was well characterized by Brunauer–Emmett–Teller, Barrett-Joyner-Halenda, scanning electron microscopy, elemental analysis, FT-IR, and solid-state ¹³C nuclear magnetic resonance. The new surface exhibits good thermal stability determined by thermogravimetric analysis, and a good chemical stability as investigated in various acidic and buffer solutions. The adsorption properties were investigated using Cu(II), Pb(II), Cd(II), and Zn(II) metals by varying all relevant parameters including pH, contact time, concentration, temperature, kinetics, and Langmuir isotherms. The adsorption efficiency increases with increasing pH and follows pseudo-second-order kinetics. The maximum equilibrium time was found to be 30?min for all metal ions. The thermodynamic analysis (ΔH°, ΔS°, and ΔG°) revealed that the adsorption was endothermic and spontaneous.