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ABSTRACT
Eskisehir sepiolite (SEP) was given a hydrophobic surface through acid treatment followed by silanization. The silanization process was realized with trimethoxy(octadecyl)silane (TMODS), (3-aminopropyl)triethoxysilane (APTES) and (3-glycidyloxypropyl)trimethoxysilane (GPTMS) coupling agents. The effects of temperature and reaction time on the silanization degree were studied within the ranges 25–50°C and 2–48 h, respectively. The efficiency of silanized SEP as an oil absorbent was investigated in pure olive oil media. The structural changes in sepiolite samples were monitored by X-ray diffraction (×RD), N2 adsorption (BET), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Fourier Transform Infrared spectroscopy (FTIR). Accordingly, maximum organic loading was achieved as 20.6% (w.) corresponding to 0.69 mmol silane/g SEP, when silanization was conducted with TMODS at 50°C for 24 h. Acid activation with hydrochloric acid removed the dolomite fraction and thus was in favor of silanization. The oil uptake capacities followed the order: GPTMS modified acid-activated SEP > APTES modified acid-activated SEP> TMODS modified acid-activated SEP > acid-activated SEP > SEP reaching as high as 2.77 ± 0.01 g/g at utmost. The augmentation in oil uptake capacity was not solely related to increased hydrophobicity, but also to altered surface area and porosity. Absorbed oil was recoverable at nearly 90% after three absorption – desorption cycles.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Novelty statement
The reported work aimed for the synthesis of chemically modified sepiolites by silanization reaction in order to attain increased hydrophobicity and concordantly enhance oil absorption capacity. Sepiolite has long been used as a nanofiller in polymeric composites. In such applications, the silanization reaction has been extensively used for the enhancement of the interfacial interaction between composite constituents and to obtain better distribution of sepiolite. Though the resulting materials were characterized in detail, very few studies focus on the properties of modified sepiolites. Moreover, the evolution of oleophilicity as a result of silanization is mostly overlooked. Also, the characterization of silanized sepiolite was studided in detail and the changes in oleophilicity were discussed in relation to material characteristics.