Advisor(s)

Akram N. Alshawabkeh

Date of Award

2011

Date Accepted

8-2011

Degree Grantor

Northeastern University

Degree Level

M.S.

Degree Name

Master of Science

Department or Academic Unit

College of Engineering. Department Civil and Environmental Engineering.

Keywords

environmental engineering, civil engineering, chemistry, chemical changes, electrochemical, groundwater remediation, iron electrolysis, redox, TCE

Subject Categories

Groundwater - Pollution, Electrolysis, Iron

Disciplines

Civil and Environmental Engineering

Abstract

Sustainable and effective technologies are required for remediation of contaminated groundwater. Iron electrolysis is a promising technology, which uses natural and low-cost materials, to enhance remediation of groundwater contaminated with chlorinated solvents.

A two-stage experimental program is conducted to evaluate chemical changes induced by iron electrolysis and its potential for enhanced electrochemical transformation of trichloroethylene (TCE). The first stage includes evaluation of changes in electrolyte pH, redox potential, and conductivity due to iron electrolysis in batch and sand-packed flow-through columns. The controlled variables selected for batch experiments include anode material (inert or iron), background electrolyte composition, electric current and polarity configuration. The controlled variables for flow-through experiments include anode material, current density, flow rate and background electrolyte composition.

The batch experiments are conducted in a glass electrochemical cell. The pH of mixed electrolyte is stable when inert (MMO) anode is used. When the iron anode is used, the pH for relatively low current density does not tend to show significant changes; however, the pH increases sharply under high current densities. Using iron anodes results in reducing electrolyte condition. Inert anode (MMO) produces an oxidizing environment when compared to iron anode due to oxygen release from the MMO anode. In addition, the distribution of pH and redox potential in the flow-through column is dependent on the applied current density and flow rate. Low flow rate does not produce significant changes in pH and redox potential until a specific period of application. When steady state condition where reached, chemicals distribution in column were similar under different flow rates.

The second stage is focused on evaluation of the role of iron electrolysis on improved electrochemical dechlorination of TCE. The controlled variables for the second stage include the anode and cathode material types, current density and initial TCE concentration. Iron anodes enhance the reductive dechlorination of TCE on the cathode surface by creating favorable electrolyte conditions for TCE reduction. Combining porous copper cathodes and iron anodes show the best dechlorination rates. The dechlorination rate constants (k) increase with increase in applied current and decrease in initial TCE concentration.

Document Type

Master's Thesis

Rights Holder

Ali Ciblak


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