Synthesis of Hydrophobic Porous Silica for Removal of Organic Contaminations from Water

Abstract

A hydrophobic porous silica material was successfully synthesized using sodium silicate as silica source, hydrochloric acid as catalyst, and trimethylchlorosilane (TMCS) as a surface modifying agent, through sol-gel and surface modification processes. The structure and properties of the fabricated porous silica were analyzed by Fourier-transform infrared (FTIR) spectroscopy, contact-angle analyzer, liquid N 2 adsorption, and scanning electron microscopy (SEM). The porous silica displayed a hierarchical porous structure and was super-hydrophobic, with contact angle as high as 156°. Specific surface area and pore volume were determined to be 566 m 2 ·g -1 and 2.28 cm 3 ·g -1 , respectively. Moreover, the porous silica could adsorb up to 14 times its own mass of toluene, gasoline, diesel, and lube oil. The abundant mesopores and macropores allowed adsorption saturation to be reached within several minutes. In addition, the porous silica was extremely hydrophobic in gasoline-water mixture and thus preferentially adsorbed organic compounds other than water. This is an important requisite of good recyclability. It was verified that, following extraction with n-hexane, the regenerated porous silica retained its initial adsorption capacity. This porous silica, with good selectivity and excellent regeneration capability for oil removal, could find novel applications in the adsorption and separation of organics from polluted water. © Editorial office of Acta Physico-Chimica Sinica.