Deuterium from electrolysis

These distillation plants concentrated deuterium from 0.0143 a/o (atom percent) to 87 to 91 a/o. Further concentration to 99.8 percent was effected by electrolysis. The average recovery of DjO from the steam fed was only 1.94 percent 360,000 mol of steam were,fed per mole of DjO produced. 

Batch electrolysis was used to concentrate deuterium from 90 to 99.87 percent at the large Savannah River heavy-water plant of the U.S. Atomic Energy Commission, at Aiken, South Carolina [B7, B8], but this final concentration step is not needed when the plant is operated at reduced capacity. 

As the most electroactive gas, H2 was the first object of electrochemical separation. In an unusual circumstance, separation was not proposed from a mixture of chemically dissimilar species such as N2, C02, etc., but rather, from deuterium, D2. It had been noted as early as the late 1930 s [4] that H2 is preferentially evolved on several cathode materials over HD or D2 during electrolysis of water ... 

No doubt Chadwick and Rutherford would have been quick to pronounce similarly on the experiments of Pons and Fleischmann, a who announced on 23 March 1989 that they had observed I sustained nuclear fusion from the electrolysis of heavy water using palladium electrodes. Deuterium is absorbed by palladium in the same way as hydrogen, but its fusion into helium does not require such extreme conditions (see page 109). All the same, these conditions have long proved impossible to sustain in physicists attempts to harness nuclear fusion for energy generation. Now two chemists were claiming that these massively expensive fusion projects could be abandoned all you needed was a test tube and two strips of palladium. 

Deuterium (2D) and tritium (3T) are heavier isotopes of hydrogen. The former is stable and makes up about 0.015 per cent of all normal hydrogen. Its physical and chemical properties are slightly different from those of the light isotope Tl For example, in the electrolysis of water H is evolved faster and this allows fairly pure D2 to be prepared. Tritium is a radioactive b-emitter with a half-life of 12.35 years, and is made when some elements are bombarded with neutrons. Both isotopes are used for research purposes. They also undergo very exothermic nuclear fusion reactions, which form the basis for thermonuclear weapons (hydrogen bombs) and could possibly be used as a future energy source. 

By far the most frequently encountered deuterium compound is D20 or heavy water. This material is generally obtained by enrichment from natural water by electrolysis. 

Deuterium as D20 is separated from water by fractional distillation or electrolysis and by utilization of very small differences in the free energies of the H and D forms of different compounds, the H20—H2S system being particularly favorable in large-scale use ... 

The scientific world was stunned in March of 1989 when two electrochemists, Stanley Pons and Martin Fleischmann, reported that they had obtained evidence for the occurrence of nuclear fusion at room temperatures. During the electrolysis of heavy water (deuterium oxide), it appeared that the fusion of deuterons was made possible by the presence of palladium electrodes used in the reaction. If such an observation could have been confirmed by other scientists, it would have been truly revolutionary. It would have meant that energy could be obtained from fusion reactions at moderate temperatures. 

The rewards of a workable nuclear fusion process would be great. Fusion produces neither the long-lived radioactive nuclides that accompany nuclear fission (although tritium requires care in handling) nor the environmental pollutants released by the burning of fossil fuels. Although deuterium is present in only 1/6000 of the abundance of ordinary hydrogen, its separation from the latter by the electrolysis of water is readily accomplished, and the oceans contain a virtually unlimited quantity of deuterium. 

When considered with regard to the amount of water available on earth it is sufficient to provide energy for many thousands of years. Moreover, deuterium can be separated from the water by electrolysis. Electrolysis is a simple, efficient process. The other fuel, tritium, is a slightly radioactive, electron emitting, isotope of hydrogen with a 12.5 year half-life. Tritium is produced from lithium by reaction with neutrons. 

The electrolytic process was also used by the Manhattan District, at Morgantown, West Virginia, and at Trail, British Columbia [M8], to refine crude heavy water from a primary plant where some process other than electrolysis was employed. These electrolytic plants were operated batchwise. The cells had no diaphragm, so the product was a mixture of hydrogen and oxygen. The gases were recombined in a burner, and the water was recycled to the primary plant when its deuterium content was leaner than primary-plant product or to the next batch of the electrolytic plant when its deuterium content was richer than primary-plant product,... 

Figure 13.16 is a flow sheet for a plant for the case in which hydrogen from stage 5 and higher is burned and recycled. The fraction of deuterium in the feed that is recovered is only 0.238. This low recovery is characteristic of the electrolytic process when used as the sole means of concentrating deuterium. As a result, the amount of heavy water that could be produced by electrolysis alone, even at a large electrolytic plant, is small. 

Electrolysis of water produces hydrogen gas at the cathode, which contains a lower proportion of deuterium than the original water. The isotope effect stems from the... 

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