NTA aids promethium separation and purification - Chemical

Nov 6, 2010 - However, he says, the DTPA ion exchange elution flowsheet surfers from two deficiencies. First, in the normal DTPA elution sequence, ...
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Chemical & Engineering

NEWS APRIL 15, 1968

The Chemical World This Week FASEB convenes this week in Atlantic City Probably never in its 52 annual meetings has the Federation of American Societies for Experimental Biology (FASEB) assembled amid greater anxiety and social turmoil. This week, as FASEB convenes in Atlantic City, violence in the cities and possible truce negotiations in Vietnam are still very much in the news. Yet life goes on in the laboratory and the record 22,000 registrants have their own professional problems to worry about. Namely, a growing lack of research money. And it's likely that the belt-tightening will continue, because the cost of curing the country's social ills will continue to put pressure on the national budget and thus compete with the demands of scientists. Last year, Dr. Ivan Bennett, number two man behind Dr. Donald F. Hornig in the White House Office of Science and Technology, spoke before the general session and soberly gave the biologists notice that the research honeymoon was over. Money was going to get scarce. More than ever they would be forced to justify their basic research projects before the granting agencies and before Congress. For many years the pace and character of biomedical research went unquestioned. Now, however, a fundamental historical shift was altering not only the missions of the agencies but also America's social goals. This year, Vice President Humphrey had been scheduled to address the meeting. (At press time, Surgeon General William H. Stewart was set to take his place.) In his talk, the Vice President had planned to deal with one of America's international social goals: overcoming world hunger through scientific knowledge. The President's science advisory committee last year said the world food problem called for a "massive, long-range, innovative effort unprecedented in human history." Thus, in this context, biology's international challenge only intensifies its domestic travail. That is, the promise of even more competition for federal funds. What FASEB and every other scientific society seems to be challenged

FASEB meeting keeps pace with federal R&D budget 1

Year

Federal R&D Expenditures (Billions)

Attendance

Number of Papers

1958

$ 4.99

9,136

2200

1959

5.80

10,327

2489

1960

7.74

11,015

2643

1961

9.28

12,567

2823

1962

10.37

14,814

2986

1963

11.99

16,484

3280

1964

14.69

16,326

3026

1965

14.87

18,957

3431

1966

15.304

21,160

3190

1967

16.509

3200

1968

16.734

20,808 22,000 (est.)

with is to preserve the purity of their research endeavors while offering pertinent technical data to a world that needs it. It may be that they cannot have it both ways. At any rate, the "science in the cause of man" message has penetrated FASEB, a loosely structured society composed of biochemists, physiologists, immunologists, pathologists, pharmacologists, and nutritionists. Several weeks ago it established a public affairs office headed by Robert Grant. Its goal for the moment is to keep the society's 10,000 members current on public policy issues that directly affect their careers. An issue that presently bristles with controversy is the exchange between Rep. L. H. Fountain and the National Institutes of Health, bioscience's chief benefactor. The North Carolina Democrat has been stinging NIH with criticism of its administrative policies since 1961. Only 10 days ago, the Congressman aimed his latest barb at NIH—a blistering comment on an NIH report defending its policies against an earlier Fountain critique. In that report, Rep. Fountain had attacked NIH's handling of its institutional grant program, mainly one that went out to the Sloan-Kettering Institute for Cancer Research. The draft, too, is a critical problem in the minds of most scientific societies, and the federation has already urged its members to take their cases to Congress.

3100

NTA aids promethium separation and purification By substituting nitrilotriacetic acid (NTA) for diethylenetriaminepentaacetic acid (DTPA) in the separation and purification of promethium from rare-earth fission products, BattelleNorthwest chemists have obtained kilocurie quantities of high-purity promethium. According to Battelle's Dr. E. J. Wheelwright and his coworker T. R. Myers at the Hanford facility, not only is the ion exchange separation markedly superior but the processing time is twice as fast when NTA is used. Prior to the Battelle findings, Dr. Wheelwright explains, DTPA was the eluting agent of choice for the separation of promethium from neighboring rare-earth elements present in spent reactor fuel. However, he says, the DTPA ion exchange elution flowsheet surfers from two deficiencies. First, in the normal DTPA elution sequence, yttrium—a fission product present in most promethium feed solutions— elutes in a position between samarium and promethium, which results in an increase in the percentage of promethium that must be recycled from each run. This is due to a larger fraction of the total promethium in the Y-Pm binary mixture zone than that found in the Pm-Nd zone in the DTPA elution sequence; Cm+ 3 , APRIL 15, 1968 C&EN

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Am+ 3 , Gd+ 3 , Eu+ 3 , Sm+ 3 , Y+ 3 , Pm+ 3 , Nd+ 3 , and Pr+ 3 . However, when NTA is used, a shift in the elution order of the rareearth series occurs and yttrium is removed from the critical Sm-Pm-Nd zone. Thus, the elution order is Y+ 3 , Gd+ 3 , Eu+ 3 , Sm+ 3 , Pm+ 3 , Nd+ 3 , and Pr+ 3 . The second deficiency relates to the time needed to reach the maximum degree of separation allowed by thermodynamics and the physical geometry of the processing equipment. With DTPA, the separation efficiency in purifying promethium decreases rapidly when the rate of advance of the absorbed band is increased beyond 0.36 milliequivalent per min.cm. 2 , Dr. Wheelwright says. With NTA, at least a 100% increase in the rate of band advance can be achieved while maintaining a separation efficiency at least equal to that obtained for the current DTPA process. From the standpoint of promethium production, an economic advantage is gained by switching from DTPA to NTA, as the shorter time cycle results in less resin radiolysis per run. This increases the number of production runs which can be made before the resin must be discarded. Moreover, NTA costs only half as much per pound as DTPA, Dr. Wheelwright points out. Although NTA is the better eluting agent for promethium, DTPA has a significant role in fuel reprocessing operations, the Battelle chemist hastens to add. For example, in recent work by Dr. Wheelwright and coworkers L. A. Bray and F. P. Roberts the simultaneous recovery and purification of promethium, americium, and curium was accomplished by

NTA as eluting agent in purifying promethium halves processing time

Battelle's Dr. Wheelwright Kilocurie quantities

use of alternate DTPA and NTA cation-flowsheets. According to Dr. Wheelwright, the sequential use of the two complexants permits a first-cycle separation with DTPA in which four fractions are collected; a Cm-Am Gd fraction, a Pm product fraction, a Pm recycle fraction, and a waste fraction. The second cycle, using NTA, separates curium from americium with gadolinium between them. The result of this technology—a joint effort by Atlantic Richfield Hanford Co., and Battelle-Northwest— was the purification of 60 grams of curium, 1100 grams of americium, and 150 grams of promethium (about 150 kilocuries) from 13& tons of Shippingport Reactor Blanket fuel elements. This work, Dr. Wheelwright notes, is the first demonstration on an appreciable scale of the recovery of these radioisotopes from material typical of spent power reactor fuels. The two companies are both prime contractors to the Atomic Energy Commission at Hanford. Although extensive industrial uses for these isotopes do not now exist, they are being considered in aerospace applications, such as fuels in converters to produce electricity.

cyclical oversupply situation during this period with production and consumption coming into balance by 1971 at about 3.6 million tons. Such are the supply-demand projections of American Zinc Co. chairman Richard A. Young and American Smelting and Refining Co. vice president Simon D. Strauss. Speaking in Montreal at the joint annual meeting of the Lead Industries Association and the American Zinc Institute, both industry experts voiced some apprehension about zinc's next four years. Mr. Young feels that the zinc industry is planning to build itself a "problem of major proportions. Anyone planning additional smelting capacity should carefully reassess the zinc markets," he says. Mr. Strauss says that he hopes his estimate for a 47c annual growth rate in zinc consumption proves to be overly conservative. Another leading zinc producer confides to C&EN: "I'm worried." Currently, Free World production and consumption of zinc are in excellent balance, Mr. Young says, partly because the U.S. lost about 100,000 tons of smelter production in the second half of 1967 during the steelworkers strike. As a result of this loss, excessive inventory stocks were consumed. At the end of last quarter, Free World metal inventories at the smelters were at comfortable levels, he adds. Discussing latest figures from the International Lead and Zinc Study Group, Mr. Young projects that the Free World's mines will increase their production of zinc by 660,000 tons over the next four years, bringing annual production in 1971 to about 4.5 million tons. These increases of 165,000 tons a year reflect a healthy an-

Serious zinc oversupply looms if planned capacity is added 0.40 0.60 Mass Flow Rate (milliequivalents/min-cm2) 15 gm NTA/L; pH 7.00

25 gm NTA. 1 ; pH 6.40

O 20 gm NTA/L; pH 7.00

v 15 gm DTPA, L; pH 6.50

20 gm NTA/L; pH 6.40

O 20 gm DTPA/L; pH 6.50 • 25 gm DTPA L;pH 6.50

NTA: nitrilotriacetic acid DTPA: diethylenetriaminepentaacetic

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C & E N A P R I L 15, 1968

acid

A serious oversupply situation looms if the Free World's zinc producers increase today's 3.7 million tons of annual capacity by the 1.2 million tons they now plan to add by 1971. In contrast, the Free World's lead producers will see only a moderate and

Zinc Institute's John Kimberley More international