Multifunctional Composite Aerogels—As Micropollutant Scavengers

Abstract

AbstractComposite aerogels are low-density porous material with a high surface area, facilitating their application in wastewater treatment. The surface of these aerogels can be modified based on the ionic charge of the target pollutants. Improved properties like high gas holdup, a low mean free path of diffusion, high mechanical strength, and integrated 3D gel architecture make them an ideal matrix for several environmental applications. This review focuses on carbon, silica, metal-based, and biopolymer composite aerogels toward effluent treatment. The challenges in the synthesis of aerogels using various reduction methods and strategies for surface modification of aerogels having improved water treatment properties are compared. Composite aerogels’ application for removing textile dyes, heavy metals, and pesticides, and the oil separation is discussed along with relevant reaction kinetics. The adsorptive and photocatalytic removal of micropollutants by aerogels are also compared. Though several novel composite aerogels have been experimented with in wastewater treatment, the toxicity implications limit their extensive scale application. The toxicity of precursor compounds such as polyacrylonitrile, resorcinol–formaldehyde, phenol, Tetramethyl orthosilicate (TMOS), and leaching of nanoparticles from aerogels are discussed. As a solution to these impediments, bio-aerogels’ use and further improvement for water treatment are highly warranted. The possibility of using aerogels in large-scale applications in moving toward a sustainable circular economy is also emphasized.KeywordsAerogelsSynthesisMicropollutantsReaction kineticsEcotoxicology