Advanced nanomaterials for water treatment: environmental aspects

Abstract

With water scarcity rising as a global issue, finding solutions for new sources of water has become a pressing need. Researchers are playing an active role in finding such solutions like seawater desalination techniques, treatment and reuse of sewage and industrial wastewater, obtaining water from steamy air, and other techniques. Wastewater treatment technology is considered as one of the easiest and least expensive solutions due to its ease of implementation and its capability of producing large quantities of treated water suitable for usage. One of the techniques used for wastewater treatment, and most widely used is adsorption (adsorption of harmful substances present in wastewater on the surface of advanced nanomaterials). The adsorption process depends mainly on the surface area of the adsorbent materials and the presence of functional groups on their surfaces that facilitate the bonding of adsorbent particles, so advanced nanomaterials have an effective and vital role in this process. One of the most important of these materials is graphene, which has a very high surface area, and it has been prepared in the form of a porous aerogel form through the freeze-drying method. Analysis showed that graphene oxide consists of sheets with a high surface area and a high density of oxygen groups at the edges. These sheets provide more adsorption sites and active centers for adsorption of heavy metal ions (iron and others). Graphene oxide has proved to be effective for removing heavy metal ions in water treatment. Other nanomaterials such as cobalt oxide distributed in a matrix of silica showed a high ability to remove methylene blue dye from industrial wastewater. In addition, activated carbon materials from agricultural waste, which have proven their ability to remove hydrogen sulfide from petroleum wastewater. Also, multi-walled carbon nanotubes doped with magnetic iron oxide were studied to remove mercury ions from water. In conclusion, studies have shown that the advanced nanomaterials have a high ability to remove pollutants (dyes and metal ions) from water for reusage for various purposes, including agriculture.