Nanomaterials-based adsorbents for remediation of microplastics and nanoplastics in aqueous media: A review

Contamination of water resources with inorganic and organic pollutants presents a great challenge for aquatic, human, and wildlife sustainability. Microplastics (MPs) have also been identified as ubiquitous environmental pollutants. The widespread use of plastic products, their long persistence in the environment, and improper disposal result in the generation and accumulation of MPs in the environment. They have been detected in various kinds of water, such as wastewater, seawater, freshwater, and drinking water. Recently, they have been detected even in human blood, deep lung tissues, and human placentas, indicating a severe exposure of human beings to these contaminants. It is important to remove such hazardous contaminants from the water to make it suitable for human consumption. Adsorption is one of the advantageous technologies for water treatment due to its simplicity, low-cost, and efficiency. Nanomaterials are excellent adsorbents due to their high surface area, ease of functionalization, and high affinity toward various pollutants. In this review, we have presented an overview of emerging applications of nanomaterial-based adsorbents, such as metal-organic frameworks, bio-based nanomaterials, carbon-based nanomaterials, and layered double hydroxides, for adsorptive removal of MPs from aqueous media. These materials have shown excellent performance in removing MPs under different experimental conditions. However, research in this area is in its infancy stage from many aspects, and several questions remain unanswered. Ultimately, we provide a brief account of the strengths, weaknesses, and future research dimensions of nanomaterial-based adsorbents for removing MPs from aqueous media.