Removal Studies of S2- Based on SBA-15-Pb(II) Composite

SBA (Santa Barbara Amorphous)-15 nano mesoporous molecular sieve was successfully synthesized by hydrothermal method and after its adsorption of Pb²+ the prepared material was used to adsorb S²- from aqueous solution. The surface and pore structure of SBA-15, the (SBA-15)-Pb(II), and the composite material of S²- adsorbed by the (SBA-15)-Pb(II) were characterized by powder X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and low-temperature nitrogen adsorption-desorption isotherm. The effects of solution acidity, S²- concentration, contact time, and temperature on the adsorption of S²- by the (SBA-15)-Pb(II) were investigated. The optimized adsorption conditions were obtained. The adsorption rate for S²- by the (SBA-15)-Pb(II) reached 96.33 %. The change of Gibbs free energy in the adsorption process, G° 0, can judge that the adsorption process is spontaneous. The enthalpy change in the adsorption process is less than zero, showing that the adsorption process is an exothermic reaction. The negative value of entropy change indicates that the adsorption process is a process of entropy reduction. The adsorption of S²- by the (SBA-15)-Pb(II) belongs to the pseudo-second-order kinetics. Freundlich isothermal adsorption equation can better describe the adsorption process. A novel method has been developed to adsorb S²- from wastewater.