A comprehensive review on magnetic carbon nanotubes and carbon nanotube-based buckypaper- heavy metal and dyes removal

ABSTRACT Industrial effluents contain several organic and inorganic contaminants. Among others, dyes and heavy metal introduce a serious threat to drinking water bodies. These pollutants can be noxious, or carcinogenic in nature, and can be harmful to mankind and different aquatic species. Therefore, it is of high importance to remove heavy metals and dyes to reduce their water and environmental toxicity. This has led to extensive research for the development of novel materials and techniques for the removal of heavy metals and dyes. One route to the removal of these pollutants is the utilization of magnetic carbon nanotubes as adsorbents. Magnetic carbon nanotubes hold remarkable properties such as surface-volume ratio, higher surface area, convenient separation methods, etc. The suitable characteristics of magnetic carbon nanotubes have led them to an extensive search for their utilization in water purification. Along with magnetic carbon nanotubes, the buckypaper (BP) membranes are also favorable due to their unique strength, high porosity, and adsorption capability. However, BP membranes are mostly used for salt removal from the aqueous phase, limited literature shows their applications for removal of heavy metals and dyes. This study focuses on the existence of heavy metal ions and dyes in the aquatic environment, and methods for their removal. Various fabrication approaches for the development of magnetic-CNTs and CNT-based BP membrane are also discussed. With the remarkable separation performance and ultra-high-water flux, magnetic-CNTs, and CNT-based BP membranes have a great potential to be the leading technologies for water treatment.