Sorption of organic compounds with different water solubility on octadecyltrichlorosilane-modified titanate nanotubes

The potential of adsorptive removal of organic compounds with a wide range of solubility (Sw) from 55 to 75,000 mg/L onto octadecyltrichlorosilane (OTS) modified titanate nanotube (TNT) was investigated. The examined organic adsorbates included trichloromethane, benzene, toluene, ethylbenzene, propylbenzene, n-pentanol, m-cresol, and phenol. The adsorbent was prepared via a hydrothermal method to produce TNT that was modified by the OTS. Effects of OTS modified process on the revolution of microstructure and surface chemistry characteristics of TNT were characterized with XRD, nitrogen adsorption–desorption isotherms, and FTIR. It was found that the prepared TNT weakly adsorbed low-Sw organic compounds, but exhibited high uptakes for organic compounds with high Sw values. The OTS-modified TNT (OTNT) possessed both hydrophilic and hydrophobic surface and it could uptake organic compounds with a wide range of Sw values. The isotherms of low-Sw organic compounds on the OTNT approached to linearity and the adsorption capacities were inversely proportional to their Sw values, implying that the dominating sorption mechanism was partitioning. The isotherms of the high-Sw organic compounds were concave downward curves, indicating that the organic compounds were adsorbed on the sites that were not covered by OTS. It was experimentally concluded that the OTNT might be considered to be an excellent adsorbent which could effectively uptake organic compounds with a wide range of solubility due to its amphiphilic characteristics.

► We used octadecyltrichlorosilane to modify surface of titanate nanotubes to produce an amphiphilic adsorbent.
► The properties of amphiphilic adsorbent were examined using SEM, FTIR, XRD, and nitrogen adsorption–desorption isotherms.
► The adsorbent was used to adsorb the organic compounds with various water solubilities.
► The produced absorbent will become an excellent material to remove organic contaminants with wide range water solubilities.