Hydrogels: Novel materials for contaminant removal in water—A review

This review focuses on contaminant removal from water using hydrogel-based materials. It highlights the recent results achieved, unresolved problems, and possible developments. Polymer and graphene hydrogels are promising new materials for removing inorganic (e.g., metals and metalloids) and organic (e.g., dyes) trace contaminants from water. They can be prepared as composites with practically any desired conventional or innovative adsorbent, to enhance the removal efficiency. Obtaining a three-dimensional highly effective network is one of the significant features of hydrogels, which confer specific characteristics on them. There are number of benefits of using hydrogels: easy separation and handling, the facility for large-scale application, and the ability to regenerate and reuse the hydrogels. At present, the experiments based on hydrogels for water purification are mostly limited to the laboratory scale and further research needed to move toward large-scale industrial applications. Moreover, the present studies are currently limited to a few types of contaminants, so that further experiments needed for removal of more contaminant types and mixtures of contaminants, considering that in practical situations. All these features are described and discussed in this review, which, to the best of our knowledge, is the first comprehensive review on hydrogel applications for contaminant removal from water.