Structure-based classification and performance analysis of superhydrophobic and superoleophilic oil absorbents/adsorbents for oily wastewater treatment and oil spill cleanup: A comprehensive review

Recently, oil spill treatment has become a significant issue due to oil leakage accidents and oily industrial wastes, resulting in numerous articles being published. However, most approaches for oil spillage cleanup have limitations, and the cleaning method should be suitable for seawater. One applicable method in seawater is employing oil absorbents/adsorbents, but most of them have low selectivity for oil, meaning they will not completely clean the water or make the collected oil reusable. Accordingly, in this review, the works aiming for oil spillage treatment using superhydrophobic absorbents/adsorbents have been reviewed. Superhydrophobic absorbents/adsorbents, due to their strong water-repelling ability, have high selectivity for oil. Moreover, some superhydrophobic absorbents/adsorbents can absorb/adsorb emulsified oil in water. Consequently, this type of absorbent/adsorbent will reduce final costs and environmental impacts. This review paper provides an overview of previous studies and their pros and cons to help future researchers find inspiration for more advanced and thorough studies. In this review paper, the urgency of oil spill cleanup is discussed in the introduction, and the superiority of employing superhydrophobic absorbents/adsorbents is compared to other types of treatment. Section 2 provides information about superhydrophobic absorbents/adsorbents' durability, selectivity, physical structure, chemical properties, reusability, mechanical stability, etc. The physical structures of the absorbents/adsorbents were compared in Section 3. Finally, in Section 4, some research opportunities and ideas are presented based on previous publications.