Hydrophobic modification of sepiolite by fatty acids for efficient oil removal: Influence of the alkyl chain length

Oil pollution has seriously affected the ecological balance, and the development of an efficient and low-cost sorbent material to treat oil pollution is work with practical applications. In this work, a novel hydrophobic sorbent based on natural sepiolite was obtained by modifying with four saturated fatty acids with different carbon chain length and used for oil removal from water. The original and modified samples were tested for SEM, XRD, FTIR, CA, XPS and BET analysis. The results showed that the functional groups of the modifier were successfully grafted onto the sepiolite surface. The sepiolite fibers changed from the original agglomerative morphology to more dispersed with a coarser surface. The contact angle of modified sepiolite was improved greatly compared with the original sepiolite. Among them, octadecanoic acid modified sepiolite (O-SEP), with a lower water contact angle showed the best diesel removal efficiency, indicating that there was no significant positive correlation between the oil sorption efficiency and the value of the contact angle. This study presented a simple and feasible method to produce hydrophobic-based sorbents with good performance based on clay minerals that could be used for oil spill cleaning up.