Nanomaterials-modified disposable electrodes and portable electrochemical systems for heavy metals detection in wastewater streams: A review

Monitoring heavy metals in wastewater streams is necessary to comply with standard governmental water treatment and discharge policies. Electrochemical heavy metal detection is a promising technology for developing miniaturized systems equipped with disposable electrodes. Such electrodes and/or systems are required for point-of-care and field-based requirements of sample analysis. In this review, comprehensive and up-to-date coverage of both disposable electrodes and portable systems is provided. The types of electrodes are discussed based on the substrate material used, e.g., carbon, plastic, metal, paper, and glass. For each substrate material, the recent studies reporting the utilization of such material for disposable electrodes are reviewed. In addition, recent advances related to hand-held and compact portable potentiostat devices at the research and development stage are summarized. Finally, commercial electro-analytical devices used for general electrochemical analysis applications and specifically for heavy metal removal from wastewater samples are summarized. Such electrodes and/or systems showed low detection limits and wide linear ranges comparable to standard laboratory-based instruments. However, more work is required to advance this field of research and develop commercial devices showing enhanced performance, short analysis duration, and low overall cost.