Adsorption of organics onto an high-area C-cloth electrode from organic solvents and organic solvent/water mixtures

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2003-04, Vol.546, p.59-72
• Main Authors: Niu, Jianjun, Conway, Brian E.
• Format: Article
• Language: English
• Subjects: Adsorption; Aniline; Carbon-cloth electrode; Chemistry; Electrochemistry; Electrosorption; Exact sciences and technology; General and physical chemistry; Organic solvents; Pyridine; Study of interfaces; UV spectrometry; Waste-water purification
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/S0022-0728(03)00146-3

The application of high-area C-cloth electrodes as effective adsorbent materials in organic solvents and in aqueous/organic solvent mixtures was studied using aniline and pyridine as model adsorbate solutes. These were selected in relation to understanding the adsorption and electrosorption behaviours of organic pollutants in such aqueous/non-aqueous mixtures and to development of methodology for clean-up of organic solvents or industrial waste-waters. The adsorption/electrosorption processes were followed by in situ UV-spectroscopy which also provided dynamical data for easy kinetic analysis. Large differences in the (apparent) double-layer capacity of the C-cloth observed in ethanol (EtOH), n-propanol, and acetonitrile (MeCN), in relation to that in water, suggest the significance of differences of solution conductivity determining the distributed electrolytic resistance in the pores of the C matrix, as in the model of de Levie. Adsorption of both aniline and pyridine was found to be significantly promoted by either galvanostatic or potentiostatic polarization of the C-cloth electrode, as previously found for aqueous solutions. Introduction of organic solvents into aqueous solution was shown to have strong positive or negative effects on the electrosorption processes depending on the respective solvents and adsorbates used, and the role of hydrophobic effects in adsorption from aqueous media. A common enhancement of extents of adsorption of both aniline and pyridine in each of the organic solvents investigated was also found by measurements of adsorption on open-circuit followed by electrosorption upon polarization.