Separation of toxic contaminants from water by silica aerogel-based adsorbents: A comprehensive review

Every day, water sources are polluted with various contaminants due to destructive human activities. In the past, humans released a lot of sewage into water bodies. Today, this is no longer an option, and environmental protection agency regulations are in place to reduce pollution. As knowledge and understanding regarding public health increased, incentives to find ways to isolate pollution from water sources and industrial wastewater also increased. After knowing the pollutants, choosing the right method is a priority. Adsorption is one of the most widely used methods with easy operating conditions, which can be applied using several low-cost adsorbents. Among different sorbents, silica aerogel (SA) is a suitable adsorbent for removing toxic substances from water and has unique properties. In this study, contaminants like dyes, heavy metals (HMs), Pesticides and herbicides (P&H), phenolic compounds, pharmaceutical and radioactive pollutants (RPs) and nitrates are considered, and different methods to remove these pollutants are investigated. Also, various types of SA-based adsorbents are reviewed and discussed. Finally, according to previous studies, the appropriate type of silica adsorbent is introduced for the separation of each pollutant.