Clay–Biomass Composites for Water Purification

Abstract

Adsorption is one of the most commonly used water/wastewater treatment processes. Clays and biomasses have been studied widely as adsorbents for different classes of contaminants. However, these materials possess some drawbacks that prevent their application on a large scale. To overcome their drawbacks, attempts have been made in recent years to synergistically combine these two classes of low-cost adsorbents to form a new class of materials called clay–biomass composites. This paper reviews the studies reported in the recent past on the use of these composites synthesized from clay and biomass, and subsequently modified, for removal of different classes of pollutants. Synthesis of composites by different methods, and the characterization of resulting composites are presented. Further, detailed discussion on the use of these composites for removal of different classes of pollutants such as heavy metals, dyes, nutrients, dyes, organic micropollutants and microbial pathogens is included. Various factors affecting the adsorption process along with mechanisms of removal of different pollutants by these composites are presented. Reported studies on regeneration and reuse of spent adsorbents are also given. It is evident from the literature review that the clay–biomass composites show significant enhancement of adsorption capacity for different classes of pollutants. Directions for further research for utilizing these composites in industrial applications are discussed. Overall, the paper indicates the potential of these composites for use in removal of different classes of pollutants.