Carbon nanotubes for heavy metal removal: Advanced adsorption and detection strategies

Since the early ۲۰۰۰s, extensive research has focused on developing effective materials and technologies for removing heavy metals from industrial wastewater due to their severe toxicity, persistence, and bioaccumulative nature. Traditional methods, such as chemical precipitation, ion exchange, membrane filtration, and adsorption using activated carbon, have been widely used; however, these approaches often have limitations, including low efficiency, high costs, and secondary pollution. In contrast, carbon nanotubes (CNTs) have emerged as highly efficient adsorbents, providing superior performance because of their large specific surface area, tunable surface chemistry, and unique hollow cylindrical structure. This review summarizes research from ۲۰۰۰ to the present, focusing on the comparative performance of CNTs, particularly as-grown, oxidized, and functionalized forms, in adsorbing and removing heavy metals compared to conventional materials. The underlying adsorption mechanisms, dominated by surface complexation and electrostatic interactions between metal ions and functional groups on CNTs, are discussed in detail. It highlights the dual functionality of CNTs in both adsorption and sensing applications, as well as their integration into advanced solid-phase and liquid-liquid extraction techniques for rapid and sensitive monitoring. Overall, CNTs represent a versatile and promising platform for environmental remediation, outperforming many traditional methods in efficiency, reusability, and detection sensitivity.

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Keywords: CNT ، Extraction ، Heavy metal ions ، Adsorption ، Aqueous Samples