Removal of emerging pollutants by clay and clay-nZVI nanocomposites-A review

Abstract

ABSTRACT Emerging pollutants (EPs) are the contaminants in the environment that have been extensively studied over the past two decades and can include anthropogenic and naturally present chemicals such as pharmaceuticals, personal care products and their derivatives, counterfeit drugs, engineered nanomaterials, and antibiotic resistance genes. Unfortunately, the present wastewater treatment technologies fail considerably to remove the EPs from the contaminated aqueous systems. Therefore, increasing attention is paid to clay nanocomposites, especially nanoscale clay-supported zero-valent iron (nZVI) composites, as an attractive remediation material for environmental clean-up. The clays and various clay minerals are plentiful and quite inexpensive. They are being applied as effective sorbents to treat various water pollutants. These minerals with outstanding physicochemical properties can be excellent candidates for supporting the matrix of nZVI. The review's main focus is to highlight the applications of the clay nanocomposites and clay–nZVI composites for the removal of different types of emerging contaminants alone or in combination with heavy metals and to understand the possible reaction mechanism. Further, removing different types of emerging pollutants by the clay–nZVI composites has been elaborated, emphasizing the onsite remediation approaches. Finally, the current challenges and future research directions on utilizing nZVI–clay-based composites for treating emerging water pollutants are also highlighted.