Tailored fly ash materials: A recent progress of their properties and applications for remediation of organic and inorganic contaminants from water

Abstract

Fly ash (FA) is the by-product of coal combustion, which is known to be an environmental pollutant. India produces about 221 million tons of Coal Fly ash annually. A large area is required for the disposal of fly ash as it can cause secondary land and water pollution. Improper disposal of fly ash has become a common issue and caused a waste of a lot of resources. However, coal fly ash has proven its worth, and today fly ash, due to its cementitious properties, is widely used in cement production, and it is also a promising adsorbent for water treatment. Fly ash was studied effectively for the removal of various pollutants from wastewater. The chemical and pozzolanic properties make fly ash very useful for water remediation. Phenols and substituted phenols, dyes including methylene blue (MB), methyl orange (MO), etc., heavy metal ions like Hg, Cu, Cr, As, Pb, etc., pesticides, and many other organic and inorganic ions like fluoride and phosphate are present in wastewater. These pollutants can be removed by adsorption process using fly ash. In this paper, different adsorption isotherms and adsorption kinetics used for the removal of various contaminants from wastewater are also discussed. Photocatalytic property and various ways of utilizing fly ash and modified fly ash for wastewater treatment are also discussed in this paper. Lastly, future research and prospects for the utilization of fly ash for water remediation are also highlighted.