When the Industry Charged Ahead
In the 1890s, electrochemistry energized the growth of the chemical enterprise.
A convincing case can be made that the U.S. chemical industry came of age during the final decade of the 19th century. For the first time in history, American scientists played a key role in the development of new chemical technology. In addition, U.S. chemical producers had put homegrown production methods into practice instead of borrowing processes from Europe.
Cover from 1997 Calendar, courtesy of Bioanalytical Systems, Inc.
The technology at issue was electrolysis. It quickly became the leading way to make two important chemicalschlorine and caustic soda (sodium hydroxide)which were in rapidly growing industrial demand.
The renowned British chemist Sir Humphrey Davy observed in 1807 that sodium could be isolated from soda ash by passing an electric current through it. Later, he and his protégé Michael Faraday helped formulate the laws governing the action of electricity in aqueous salt solutions. Another chemical milestone occurred when Charles Watt obtained an English patent in 1851 for producing chemicals, including chlorine, caustic soda, and sodium hypochlorite by electrolysis of brine. Chlorine formed at the anode of a cell; caustic soda and hydrogen formed at the cathode. The equation is
2NaCl + 2H2O Cl2 + 2NaOH + H2
This reaction, however, was of no more than experimental interest. It had no industrial use until two obstacles were overcome. Foremost was a source of abundant, cheap electricity. Secondly, some way had to be devised to prevent sodium formed at the cathode from reacting with chlorine at the anode or with other constituents in the brine. Lack of low-cost power was resolved in the 1870s when Werner von Siemens in Germany and Zenobe Gramme in Belgium developed the dynamo for generating electricity. This breakthrough led several scientists to explore ways for separating the anode and cathode in a cell.
In 1890, the German company Chemische Fabrik Greisheim-Elektron began producing chlorine and potassium hydroxide (used in making coal-tar dyes) in an electrolytic cell in which the anode and cathode were in chambers separated by a porous cement membrane or diaphragm. The apparatus was not very efficient, however.
Then the remarkably innovative but now largely unrecognized American chemist Hamilton Y. Castner devised a better system. Born in Brooklyn, NY, in 1858, Castner studied chemistry at Columbia Universitys School of Mines under Charles F. Chandler, a founding father of the American Chemical Society. He left Columbia without graduating to establish a career as an independent analytical chemist but soon devoted much of his attention to working out new chemical processes. One of the first was a method for producing sodium at relatively low cost by reducing caustic soda with iron carbide. At that time, sodium was used to prepare aluminum metal by its reaction with aluminum chloride.
Unable to obtain financial backing for his invention, he left New York for England. There, Aluminium Co. was established, using Castners inexpensive sodium to produce aluminum in 1887. As a result, the price of aluminum dropped to about 5% of its previous level. But Castners aluminum success was short-lived. In 1889, Charles N. Hall in the United States and Paul L. F. Héroult in France independently invented an even cheaper way to make aluminum by electrolysis without using sodium.
Castner then turned his efforts to manufacturing sodium cyanide, used for electroplating and extracting gold from low-grade ores. Needing high-purity caustic soda for producing sodium, he then developed a cell for the electrolysis of brine. His device consisted of three compartments separated by partitions that reached almost to the bottom. The two end compartments contained brine and a graphite anode. (Castner also invented a method for converting carbon electrodes to longer-lasting graphite.) The center compartment held just water. On the bottom of the cell was a pool of mercury, which served as the cathode. Sodium that formed there amalgamated with the mercury. When the cell was rocked, the sodium came into contact with the water in the center to produce caustic soda. Castner patented his equipment in 1892.
Kellner Joins Castner
At the same time, the Austrian chemist Carl Kellner independently worked out a similar mercury cell. Although Castners model was somewhat more efficient, the two got together to exchange patents and avoid lengthy litigation. They founded CastnerKellner Alkali Co. in 1895 for using and licensing their technology.
A plant using the CastnerKellner cell to turn out caustic soda and chlorine for preparing bleaching powder (calcium hypochlorite, made by passing chlorine gas over slaked lime) was built near Runcorn in Cheshire, England, in 1897. A few other small-scale electrolytic caustic chlorine plants had operated for a short time in England earlier in the 1890s. CastnerKellner cells also were started up in Germany, France, Belgium, Italy, Sweden, and Russia during the 1890s. By 1900, more than 30 electrolytic facilities were operating in Europe.
Meanwhile, other efforts were underway in the United States. While a student at the Massachusetts Institute of Technology in 1887, Canadian-born Ernest A. LeSuer worked out an electrolytic cell using a percolating asbestos diaphragm to separate the anode and cathode. After he graduated in 1890, an experimental unit was put into operation at a paper mill in Bellows Falls, VT. It proved so successful that a larger plant was constructed in Rumford, Maine, in 1892 to produce caustic soda by electrochemistry.
In the early 1890s, a group of investors laid plans for making soda ash in Saltville, VA, where salt, coal, and limestone were abundant. They persuaded Thomas T. Mathieson to come to the United States to run the operation, which was named Mathieson Alkali Co. Mathiesons father had operated an ammonia soda works in England until he sold out to United Alkali Co. in 1890 (see Soda Ash, Solvay Style, TCAW, Feb. 2002, p 87). But the soda ash venture was unsuccessful and Mathieson went back to England. However, the new company licensed the CastnerKellner electrolytic process and, in 1895, began turning out caustic soda and bleaching powder at Saltville on a small scale. In 1897, the company put up a much larger plant at Niagara Falls, NY.
Dow Builds Pilot Plant
Also in the mid-1890s, Herbert H. Dow was developing an electrolytic cell of his own design. Dow had formed Midland Chemical Co. in Midland, MI, in 1890 to use an electrolytic process for tapping the vast brine sources underlying central Michigan to extract bromine. Dow recognized that the brine contained much more than bromine, so he set up a pilot plant to explore ways to recover chlorine by electrolysis. When his experimental equipment blew up shortly after he turned the switch, his financial backers, who controlled the company, banned further dangerous tests.
Disgruntled, Dow went off to Navarre, OH, near Canton, to work out the kinks in his chlorine process on his own in a small experimental plant. Then he returned to Midland in 1897 to establish Dow Chemical Co. and produce chlorine for making bleaching powder. In doing so, he broke the back of the near monopoly in the U.S. bleaching powder market held by Britains United Alkali Co.
Dows rather makeshift cells were long, shallow troughs made of wood divided by wood-and-tar partitions; his electrodes were rods of carbon intended for use in arc lamps. He discarded the caustic soda that was a byproduct of the process. The hydrogen caused frequent explosions. In 1913, the company installed newly designed, more efficient cells from which it made both caustic soda and chlorine.
Another American pioneer in caustic-chlorine was Pennsylvania Salt Manufacturing Co. The company was formed in 1850 and made caustic soda from the mineral cryolite to be sold to households that prepared their own soap. In 1902, it started up a caustic-chlorine plant on top of the salt beds at Wyandotte, MI, using a mercury cell designed by George Bell in England. The cell worked poorly, but Arthur E. Gibbs, an English engineer who had been hired by Pennsylvania Salt, perfected the diaphragm cell by 1908.
A different type of cell was invented by Clinton P. Townsend, a chemist and patent attorney, and Elmer A. Sperry, an electrical engineer who later invented the gyroscope. Their cell consisted of a steel tank, the side of which served as the cathode, with graphite anodes in the center; a porous asbestos diaphragm separated the cathode and anode. In 1903, this cell came to the attention of Elon H. Hooker, an engineer who had recently launched a small venture capital firm. Hooker sent his older brother, a chemist named Albert, to evaluate the apparatus and was favorably impressed. In 1906 in Niagara Falls, NY, Hooker formed a company (soon to become Hooker Electro Chemical Co.) and built a plant to make caustic soda and bleaching powder using the Townsend cell.
Mercury Cells Costly
Today, nearly all chlorine and caustic soda is manufactured by descendents of these early mercury and diaphragm cells. In general, mercury cells turn out a purer product, but the high cost of mercury makes them expensive to install. They also must operate at a higher voltage.
An electrolytic cell produces about 1.1 lb of caustic soda for each pound of chlorine. So a market must be found for both if the business is to be economical. Caustic soda was in good demand as an industrial alkali during the early 20th century as a competitor with soda ash. But growth of the electrochemical business was hampered by lack of a strong outlet for chlorine, which was used largely for making bleaching powder.
Demand for chlorine soon blossomed, however. As newspaper circulation mushroomed at the turn of the century, mills making newsprint consumed increasing volumes of chemicals to bleach their wood pulp. Later, chlorine was in big demand for bleaching the pulp used to make rayon and cellulose acetate. And in 1910, the U.S. Army Medical Corps demonstrated that chlorine was an effective water disinfectant. The first broad trial was at Niagara Falls in 1912, after a typhoid epidemic hit the town. Over the next decade, chlorination of public water supplies became widespread. Now, by far the biggest use for chlorine is in synthesizing such chlororganic chemicals as vinyl chloride monomer, ethylene dichloride, organic solvents, and pesticides.
As their major markets have matured, output of both chlorine and caustic soda has stagnated in recent years. Annual production of the two chemicals in the United States runs between 12 and 13 million tons.
David M. Kiefer is a consulting editor for Todays Chemist at Work. Send your comments or questions regarding this article to firstname.lastname@example.org or the Editorial Office, 1155 16th St N.W., Washington, DC 20036.