Modification and Characterization of Novel Porous SiO2 Material Functionalized with C,C-Pyridylpyrazole acceptor for sulphate Removal from wastewater

Different pollutant reach every day to the ground water which is the main source of water to the Palestinian, one of these pollutants is sulfate; high sulfate concentration can unbalance the natural sulfate cycle and cause different health problem to both human beings and animals. This research involve the modification of pure porous polysiloxane SiO2 by condensing a functionalized C,C-pyridylpyrazole with a 3-glycidoxy-propyltrimethoxy-silane silylant agent, previously anchored on silica surface is reported. The epoxide group was opened yielding a receptor pendant group bonded to the inorganic surface. The Surface Modification (MS) was characterized by elemental analysis, infrared spectra, and SEM. This porous material exhibits good chemical and thermal stability determined by thermogravimetry curves and hence they can be used as perfect adsorbents to uptake sulfate from water. The concentration of adsorbate in the filtrate was determined using uv-spectrophotometry. In order to investigate the adsorption efficiency for the adsorption of sulfate onto (Si-RO-PzPyr) the effect of solution condition on each adsorption process were studied. The result showed that the product have high adsorption efficiency. These conditions that affect adsorption of sulfate were studied involve the effect of contact time, pH, temperature, adsorbent dose and the initial concentration of adsorbate. It was observed that the percentage removal of sulfate decreased with an increased initial concentration and pH while it increased with increase in solution contact time and adsorbent dose and temperature. The best equilibrium isotherm model for the adsorption process was investigated according to the value of the correlation coefficient of Langmuir and Freundlich and Temkin isotherm adsorption model. The result showed that the adsorption followed Temkin adsorption isotherm. Also the kinetic of adsorption were investigated using pseudo first-order and pseudo second-order kinetics model. The results showed that the mechanism of these reaction followed pseudo –second order kinetic adsorption model. In addition, Van't Hoff plot for adsorption in order to determine the values of enthalpy change and entropy change, and hence determining if the adsorption process is spontaneous or not, and if it is exothermic or endothermic one, the thermodynamic parameter of all the adsorption proved that these process are endothermic (∆H>0)and spontaneous (∆So>0).