Potentiometric Online Detection of Aromatic Hydrocarbons in Aqueous Phase Using Carbon Nanotube-Based Sensors

摘要

Surfaces made of entangled networks of single-walledncarbon nanotubes (SWCNTs) display a strong adsorptionnaffinity for aromatic hydrocarbons. Adsorption of thesencompounds onto the walls of SWCNTs changes thenelectrical characteristics of the SWCNT-solution interface.nUsing these features, we have developed a potentiometricnsensor to detect neutral aromatic species.nSpecifically, we can detect online aromatic hydrocarbonsnin industrial coolant water. Our chromatographic resultsnconfirm the adsorption of toluene onto the walls of carbonnnanotubes, and our impedance spectroscopy data shownthe change in the double layer capacitance of the carbonnnanotube-solution interface upon addition of toluene,nthus confirming the proposed sensing mechanism. Thensensor showed a toluene concentration dependent EMFnresponse that follows the shape of an adsorption isothermnand displayed an immediate response to the presence ofntoluene with a detection limit of 2.1 ppm. The sensor doesnnot respond to other nonaromatic hydrocarbons that mayncoexist with aromatic hydrocarbons in water. It shows anqualitative sensitivity and selectivity of 100% and 83%,nrespectively, which confirms its ability to detect aromaticnhydrocarbons in aqueous solutions. The sensor showednan excellent ability to immediately detect the presencenof toluene in actual coolant water. Its operationalncharacteristics, including its fast response, low cost,nportability, and easy use in online industrial applications,nimprove those of current chromatographic ornspectroscopic techniques.