Carbon nanotube-based extraction and electrochemical detection of heavy metals

In this mini review, recent trends and challenges in developing carbon nanotube-based extraction and electrochemical detection of heavy metals in water are reviewed. Carbon nanotubes (CNT) have electrical, mechanical, chemical, and structural properties superior to those of conventional materials, for example graphite and activated carbon. CNT-based procedures are also more efficient than traditional techniques and methods, for example liquid–liquid extraction, atomic-absorption spectroscopy, flame photometry, and inductively coupled plasma, because they can enable rapid, sensitive, simple, and low-cost on-site detection. Different forms of CNT, including as-grown, oxidised, and functionalised CNT, can be well suited to metal adsorption. The measurement procedure relies on adsorbing the metal on the CNT surface after reasonable contact time, either by applying an electrical potential or under open-circuit conditions, and subsequent quantification. Different types of CNT-based electrode, including composite, paste, and binder-free, can be fabricated and used for metal detection. Application of CNT and their novel properties to the adsorption and detection of heavy metals is discussed in detail.