A study on sorption of organic compounds with different water solubilities on octadecyltrichlorosilane-modified NaY zeolite

This article investigated the sorption capacities and sorption mechanisms of several organic compounds, benzene, toluene, ethylbenzene, propylbenzene, trichloromethane, n-pentanol, m-cresol, and phenol with different water solubilities (Sw, ranging from 55 to 75 000 mg/L) onto n-octadecyltrichlorosilane (OTS)-modified and unmodified NaY zeolite. The OTS-modified NaY zeolite (OMZ) featured an external hydrophobic surface, but its internal pores retained their hydrophilic surfaces. Several techniques – including Fourier transform infrared (FTIR) spectroscopy, BET analysis, and elemental analysis – were used to demonstrate experimentally that the OMZ was an amphiphilic adsorbent. The unmodified NaY zeolite weakly adsorbed organic compounds with values of low Sw, but exhibited high uptakes of those organic compounds that could form hydrogen bonds with the zeolite surface. For the OMZ, however, the low-Sw organic compounds partitioned to the OTS on the modified zeolite to increase their sorption dramatically, while the high-Sw organic compounds adsorbed on the internal pore surfaces to maintain their high adsorption capacities. The water solubility, molecular size, and chemical structure of the tested organic compounds were all key factors affecting their adsorption capacities. The OMZ could uptake organic compounds effectively over a wide range of water solubilities.

► We used octadecyltrichlorosilane to modify surface of NaY zeolite to produce an amphiphilic adsorbent.
► The organic compounds with high water solubilities adsorb on the internal hydrophilic pore surface.
► The organic compounds with low water solubilities partition to octadecyltrichlorosilane on the external hydrophobic surface.
► The produced absorbent will become an excellent material to remove organic contaminants with wide range water solubilities.