Carbon Nanotube Based Flow-Through Electrochemical Cell for Electroanalysis

A novel approach is proposed for increasing the sensitivity and reducing the time required for the electrochemical detection of both organic and inorganic pollutants in water. In the present work a membrane flow-through electrode made of multi walled carbon nanotubes (MWCNT) buckypaper is utilized for the detection of copper by anodic stripping voltammetry and parathion and tartrazine by adsorptive stripping voltammetry. The convective mass transfer obtained in flow condition combined with the large surface area and adsorptive properties of buckypaper enables an efficient accumulation of the analyte on the electrode surface in a short time, improving sensitivity and time efficiency. Buckypaper porous electrodes were prepared by filtration of MWCNT dispersion through a PTFE membrane and their sheet resistance and water permeation flux resulted to be inversely proportional to the thickness of the MWCNT layer. We demonstrated that for analytical applications thin membranes electrodes perform better than thick electrodes in virtue of their higher permeability and lower capacitance. In particular, buckypaper membranes with a surface mass of 0.12 mg cm⁻² enabled the detection of 64 ppt of copper in 5 min, 53 ppb of tartrazine in 2 min, and 0.12 ppm of parathion in 1 min. Thus, the electrochemical sensor based on the MWCNT porous flow-through electrode promises to be a key part of the quality control of drinking water at any level of the water supply chain. Moreover, the water permeation flux of 10200 L h⁻¹ m⁻² achievable with buckypaper membrane electrode associated with an electrical conductivity of 2200 S m⁻¹ makes this system also suitable for large scale electrochemical water treatment.