Adsorption and detection of organic pollutants by fixed bed carbon nanotube electrochemical membrane

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An electrically conductive, flow-through, fixed bed adsorption membrane (FCME) made of carbon nanotubes (CNT) installed in an electrochemical flow cell, was applied for the highly efficient adsorption and detection of organic pollutants. Three analytes with different chemical nature, i.e., parathion ethyl, tartrazine and diquat, were chosen as model systems to demonstrate the capabilities of the system. Adsorptive stripping voltammetry (AdSV) performed by the FCME provided directly the amount of analyte adsorbed; in contrast to an adsorption column, that monitors the effluent concentration. The adsorption capacity and kinetic constants were obtained by AdSV and were comparable with those predicted by the Thomas model. The FCME enabled the detection of nanomolar levels of tartrazine and parathion, and submicromolar levels of diquat with a linear range of three orders of magnitude. In addition to being a very sensitive analytical tool, FCME is an adsorption membrane that enables its simple electrochemical regeneration.