Publications

The reduction of dioxygen in aprotic media yields superoxide ions which react with polyhalogenated aromatic hydrocarbons by nuclcophilic substitution. The degradation of hexachlorobenzene to bicarbonates and chlorides using in situ generated superoxide ions was carried out at room temperature in a flow cell system equipped with a gas fed, porous electrode. The effects of current, electrolyte flow, and aprotic media on the extent of degradation of hexachlorobenzene are presented.

Newman s BAND(J) subroutine, which has been used widely to solve models of various electrochemical systems, is extended to solve a system of coupled, ordinary differential equations with interior boundary conditions. A set of coupled, linear ordinary differential equations is used to demonstrate the solution procedure. The results show that the extended technique has the same accuracy as that of using pentadiagonal BAND(J), but the execution speed is about five times faster than that of pentadiagonal BAND(J). Using sparse matrix solver Y12MAF to solve the same set of equations takes even longer time than pentadiagonal BAND(J).

A model is presented for a zinc/bromine cell that considers the effects of an increase or a decrease in the cathode channel width due to zinc removal on discharge and zinc deposition on charge, respectively. The model also includes the effect of an organic bromine complexing agent (OCA) on the cell performance. Changes in the channel width affect the catholyte velocity, cathode side pressure drop, mass transfer and potential drop in the cell, while the inclusion of the bromine complexing organic phase shows a marked effect on the available bromine in the aqueous phase. It is shown that during discharge, the release of complexed Bromine by the OCA could degrade the cell performance. A simple equation is derived and used to express the relationship between the total bromine in the organic phase and the bromine in the aqueous phase. Copyright © 1991 American Institute of Chemical Engineers

A simple mathematical model is presented and used to analyze the potential and current distributions in a HORIZON(R) sealed lead-acid battery. It was found that an increase in the thickness of an electrode would not enhance the discharge rate of that electrode; instead, it causes the transfer current distribution to be less uniform in the electrode. Also, the ohmic drop across the separator would decrease with a decrease in the thickness of the separator more rapidly when the thickness is small than when it is large. In addition, it was found that efficient high-capacity, high-rate electrodes must consider the electrode reaction kinetics because of the high sensitivity of transfer current distribution to the reaction kinetics.

An electrochemical process for the decomposition of hydrogen sulfide into its constituents in an aqueous alkaline so- lution is presented. It essentially consists of presaturation of an alkaline scrubber solution with H2S. Thereafter, partial neutralization of the presaturated solution provides not only the necessary mass balance for electrolysis, but also creates the optimum conditions under which passivation of the anode, as well as side chemical and electrochemical reactions, are minimized. Finally, the electrolysis stage of the process leads to precipitation of crystalline sulfur at the anode and evolu- tion of hydrogen at the cathode. Regeneration of the alkaline solution via an osmotic effect developed during electrolysis completes the process