A review on the synthesis and application of magnetic nanoadsorbents to the treatment of oilfield produced water

Oilfield produced water is the largest waste stream associated with oil production and is considered a major environmental concern, demanding new treatment strategies to efficiently remove its contaminants before disposal. These new technologies should be cost-effective with near-zero pollutant discharge. Adsorption with nanostructured materials has the potential to meet these characteristics since it is possible to remove contaminants present even in low concentrations, being suitable as a polishing step. Magnetic nanoadsorbents, in particular, can be easily separated after the sorption process and subsequently regenerated and reused. The present study provides a review of the technologies available for the treatment of produced water, focusing on the removal of dissolved compounds and the use of magnetic nanoadsorbents. The synthesis, surface modification, and regeneration strategies of magnetic nanoparticles and their subsequent reuse are also addressed. This class of nanomaterials is a promising alternative for the treatment of oilfield produced water, especially on offshore platforms, where weight and space limitations are crucial when choosing the ideal treatment technology.