Environmental Remediation through Electrochemical Reduction-oxidation

摘要

With awareness of environmental issues on the rise, the monitoring and remediation of pollution has become a vital focus of scientific research. In this work, electrochemistry is applied to the study of reduction mechanisms for emerging environmental pollutants and simpler model compounds. In an effort to minimize the energy needed for electrochemical remediation, solution-phase catalysts and catalytic electrodes have been employed. Mechanisms have been proposed for the reduction of 1-bromodecane and 1-iododecane in the presence of a modified, electrogenerated nickel(I) salen catalyst, and for 1,2- and 1,6-dibromohexane at silver cathodes in dimethylformamide; the reactions of these simple molecules can aid in our understanding of larger, more complex pollutants. One such pollutant is atrazine, or 6-chloro-N2-ethyl-N 4-(1-methylethyl)-1,3,5-triazine-2,4-diamine, a chlorinated herbicide commonly used in the United States. Atrazine was successfully reduced at carbon and silver electrodes in dimethylformamide; its reduction at silver occurs at slightly more positive potentials than at carbon, but requires the aid of ultrasound. Other, novel electrodes with nanomaterial surfaces containing gold, silver, and palladium were applied to the conversion of CO2 to useful fuels, and mechanisms have been proposed for the formation of formate, carbon monoxide, and oxalate in various solvents. Cyclic voltammetry was used to evaluate the electrochemical behavior of each compound of interest, and controlled-potential (bulk) electrolysis coupled with traditional analytical methods such as gas chromatography--mass spectrometry led to the identification and quantitation of reduction products. Scanning electron microscopy images of electrodes before and after electrolyses revealed key information on adsorption phenomena and electrode stability for the reduction of atrazine and CO 2.