Rice straw and rice husk-based absorbents for oil spill response

The cleanup of oil spills on water has gained increasing importance as a result of environmental regulations, and absorbents are a crucial solution in oil spill remediation efforts. Therefore, low-cost and eco-friendly oil absorbents originated from rice straw/husk for enhancing oil absorption efficiency and streamlining the recovery process were presented in this current work. Indeed, the influences of oil spills on ecosystems, properties, and weathering processes were critically reviewed. In addition, rice straw/husk characteristics for oil spill application, as well as factors affecting the oil absorption mechanism and the capacity of rice straw/husk, were scrutinized. Alternatively, the characteristics and oil absorption capacity for rice straw/husk were presented based on natural and modified rice straw/husk. As a result, raw rice straw could absorb spilled oil as much as other natural absorbents because its cellulose fibers have high pore size and volume, while raw rice husk showed very low oil absorption capacity. In the case of modification, rice straw cellulose-based aerogels and thermally treated rice husks could reach significantly high oil absorption capacity, corresponding to 130 g/g and 12.0 g/g, respectively, which is similar to that of other high-cost polymers. Finally, strategies and perspectives for utilizing rice straw/husk in oil spill response activities were analyzed in detail. In general, rice straw/husk could be considered as green absorbents towards a sustainable environment, although low-cost and eco-friendly advanced techniques should be developed and incorporated with rice straw/husk to enhance the oil absorption capacity in the future.