Preparation of hydrophobic sepiolite via a facile one-step methyltrichlorosilane vapor deposition for oil-water separation

Hydrophobic sepiolite with good oil adsorption performance is prepared by the atmospheric pressure vapor deposition method with methyltrichlorosilane (MTS) as the modifier. Systemic investigations reveal that MTS modification on the sepiolite surface introduces hydrophobic groups and enhances the oils' wetting and spreading ability on the sepiolite fibers. At the same time, bead-string-shaped SiO 2 nanowires formed by hydrolysis polymerization of MTS are observed, increasing adsorption surface and pores. Besides, the HCl hydrolyzed from MTS reacts with interlayer Mg 2+ in sepiolite's layered magnesium silicate crystal structure. This reaction leads to delamination, increasing the pore volume and pore area of sepiolite. The generated MgCl 2 products are removed by washing without causing environmental pollution. The modified sepiolite exhibits good hydrophobicity (WCA max  = 144°) and excellent oil-adsorbed capacity (saturated oil adsorption 2.29 g·g −1 ). In addition, the modified sepiolite still has excellent oil adsorption capacity (oil adsorption 2.17 g·g −1 ) after 15 adsorption-desorption cycles. Therefore, this work presents a facile and low-cost route for natural clay materials modification and its environmental application.