Development of adsorptive ultrafiltration membranes for heavy metal removal

The adsorption process has been successfully used as a technique for water and wastewater treatment over the past 40-50. years, but it is not without drawbacks as the treatment method for heavy metal removals. One of the main issues of the process is the posttreatment requirement to separate nanoparticles from the water sources. This chapter provides a review on the development of adsorptive ultrafiltration (UF) membranes composed of organic polymer and inorganic nanomaterial for elimination of heavy metal ions in a relatively simple way. The roles of different types of nanomaterials embedded in the membranes, including metal oxides (e.g., zirconium oxide, iron oxide, and titanium dioxide), carbon-based nanomaterials (e.g., carbon nanotubes and graphene oxide) and other nanomaterials (e.g., natural clays and waste) are assessed for their selectivity toward heavy metal ion adsorption. In most of the published research work, the adsorptive membranes exhibited promising results with respect to adsorption capacity and water permeability. However, more research is needed to address the possible leaching of nanomaterials from the membrane during operation and the potential of membrane degradation upon exposure to strong acid/alkali solutions during the desorption process.