Adsorption of crude oil from aqueous solution: A review

Crude oil provides a significant contribution to a country's economy, resulting in a diverse range of petroleum products that can be used to create significant income. However, the major disadvantage of using crude oil is that it depletes world water resources. This has led to a large amount of literature being churned out every year on ways of mitigating crude oil spills, particularly by adsorption. In this study, the different types of adsorbents that have been employed in the sorption of crude oil in recent times were reviewed in order to identify the best class of adsorbents needed for successful clean-up and draw conclusions from the findings. The adsorbents were grouped into seven different classes, namely: biosorbents, activated carbons, biochars, polymers and resins, clays and minerals, nanoparticles, and composites. Biosorbents were found to be the most commonly used (43.8 %) due to their abundance and ease of preparation, while activated carbon and clays and minerals (4.2 % each) were the least frequently used. The majority of adsorbents had excellent adsorption capacity and removal efficiency (>85 %). The adsorption process for all the adsorbents mainly followed the Langmuir isotherm model and correlated well with the pseudo-second order kinetic model. Sorption occurs primarily through intra-particle diffusion, film diffusion, and ion exchange. Other adsorption processes, such as the effects of operating parameters, thermodynamic studies, and adsorbent regeneration and reuse, were also discussed and recommendations outlined for futuristic studies.

Automated summary

Crude oil plays a significant role in a country's economy, but it negatively affects global water resources. This study reviews recent advancements in crude oil sorption techniques, particularly through adsorption, and categorizes adsorbents into different classes. Biosorbents are found to be the most commonly used and most effective adsorbent class. Other adsorption processes and factors are also discussed, along with recommendations for future studies.