Sequestering Groundwater Contaminants via Emerging Nanocomposite Adsorbents

Groundwater resources have seen a potent contamination threat due to a spurt in industrial and anthropogenic activities in recent years. It is the only reliable water resource for a major chunk of rural and semi-urban population and serves as a backbone for drinking water supply. Although chemical quality of groundwater is also influenced by geological conditions of the natural aquifers, the share of industrialization and urbanization is profound. Typical groundwater pollutants such as arsenic, chromium, fluoride, and nitrate are growing causes of concern due to their toxic and lethal nature if consumed in excess to human as well as natural ecosystem. Conventional water treatment technologies are inefficient and uneconomical for sequestering these contaminants. Nanomaterials and nanocomposites are composed of nanometer size particulates. Due to their ample surface area, surface charge and functionalities, they have an extensive research scope for mitigating different contaminants. Carbon-based nanocomposites made up of carbon nanotubes (CNTs) and graphene oxide (GO) have been studied widely in this regard and have resulted in excellent adsorption capacities for different heavy metals and inorganic contaminants. Recently discovered super nano adsorbents—metal–organic frameworks (MOFs) due to its unique cage-like structure also promise better outcomes. In this vein, this chapter provides a holistic approach for investigating the potential of various CNTs, GO, and MOFs nanocomposites/nanohybrids in remediation of four major groundwater pollutants-arsenic, chromium, fluoride, and nitrate. The chapter shall help the reader briefly understand the typical synthesis methods, removal mechanism and chemistry, adsorption capabilities and influence of pH on adsorption of these contaminants by different nanocomposites.