Performance of iron electrolysis for transformation of trichloroethylene in groundwater

by Ali Ciblak

Institution: Northeastern University
Year: 2016
Keywords: electrochemical; groundwater remediation; iron anode; iron electrolysis; TCE; Electrolysis; Electrochemistry; Groundwater; Purification; Trichloroethylene; Purification; Iron; Electrometallurgy; Copper; Electrometallurgy; Anodes
Posted: 02/05/2017
Record ID: 2135331
Full text PDF: http://hdl.handle.net/2047/D20200193


Groundwater contamination with chlorinated solvents, such as trichloroethylene or TCE, is a major environmental challenge. The development of innovative, efficient, and sustainable remediation technologies is needed. In this study, iron electrolysis is assessed as a potential technology for the remediation of TCE contaminated groundwater.; A three-stage experimental program is conducted in this study: (i) the evaluation of chemical changes in the electrolyte due to iron electrolysis in batch reactors, as well as the investigation of TCE degradation rates; (ii) the optimization of electrochemical operating variables using a multivariable statistical approach; and (iii) the assessment of a proposed electrochemical system under flow conditions for the remediation of groundwater contaminated with TCE.; The first phase of this study focuses on the temporal chemical changes in the electrolyte due to iron electrolysis and TCE degradation kinetics with various electrode materials. Unlike an inert anode, an iron anode releases Fe (II) into the system and generates a highly reducing electrolyte condition (lower oxidation-reduction potential). This reducing electrolyte condition facilitates the reductive dechlorination of TCE. The TCE dechlorination rate of various anode materials is investigated. The iron anode coupled with a copper foam cathode provides the best TCE dechlorination performance.; In the second stage, the significance of changes in operating variables on final TCE elimination efficiency (FEE) and specific energy consumption (SEC) is investigated using an iron anode-copper cathode couple. Under the same total charge conditions, changes in applied current impact FEE the most. For SEC, the ionic conductivity of the electrolyte is the most influential parameter.; In the final stage, a three-electrode (the sequence of an iron anode, a copper foam cathode, and an MMO anode) electrochemical system is implemented for the remediation of TCE in groundwater under flow conditions. Higher TCE removal efficiencies are reached at a lower flow rate, supporting the conclusion that a longer residence time of the electrolyte improves TCE removal efficiency. Conversely, the treating capacity of TCE is higher for a higher flow rate.