Aerogels in wastewater treatment: A review

Aerogels are highly porous and light-weighted materials with extensive surface areas. The remarkable thermal, mechanical, and chemical properties render them ideally suited as adsorbents in water/wastewater treatment. Specific search queries were used to retrieve research articles from several databases like Scopus, PubMed, and Google Scholar. The papers explicitly related to the treatment of water/wastewater by different aerogels were then screened and used to collect information related to the mechanism, kinetics, isotherms, removal efficiencies, and life cycle assessments of aerogels. This review discussed the recent advances in aerogels preparation as well. Aerogels prepared using natural, synthetic or hybrid materials could be loaded with different functional nanoparticles or subjected to chemical surface modification for efficiency enhancement. Significant advances have been made to remove various contaminants from wastewater using aerogels. Particularly, these functions are highly dependent on the pH of the medium and initial adsorbate concentration. The mechanism of absorption is mainly chemisorption with ion exchange as a mediating process, where the absorption process generally follows Langmuir isotherm and reaction kinetics of adsorptionis mostly pseudo-second-order. It was found that solution pH, p Ka of adsorbate, pH value at zero charges of adsorbent, and specific surface area of adsorbent are the major factors influencing the adsorption capabilities of aerogels from the perspective of kinetics and isotherms. Future research could investigate the unique structure of aerogels for surface engineering and functionalization to enhance overall efficiencies, as well as explore the use of waste materials to produce aerogels, thereby lowering costs and improving sustainability.