The extraction of uranyl nitrate with tetrahydrosylvane and tetrahydropyrane was imvestigated and compared with that of ethylacetate and diethylether. The effect of ammonium nitrate and nitric acid was shown and the influence of sulfate, chloride, and phosphate anions as well as calcium nitrate and ferric nitrate was examined

B. Težak

E. Bona

M. Branica

N. Šimunović

English

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CR 0 AT I CA CHEM IC A ACT A 28 (1956) 9 CCA- 2 542.61 :546.791.2.175 Extraction of Inorganic Ions with Organic Solvents. I. Continuous Extraction of Uranyl Nitrate MTith Tetrahydrosylvane and Tetrahydropyrane* M. Branica, E. Bona, N . Simunovic and B . Tefok I nstitute »Ruder Boskovic«, Zagreb and Laboratory of Physical Chemistry, FacuLty of Science, University of Zagreb, Croatia, Yugoslavia Received December 31, 1955 The extraction of uranyl nitrate with tetrahydrosylvane and tetrahydropyrane was imvestigated arnd compared with thaf of ethylac~ta,te and diethylether. The effect of ammonium nitrate and nitric acid was shown and the influence of sulfate, chloride, and phosphate anions as well as cakium nitrate and ferric nitrate was examin~d. · In the course of our work on separation of uranium from solutions of very 1ow concentration we have used the extraction of uranyl nitrate with organic solvents. According to many authors\ best results are obtained with extraction media containing oxygen bound in ether-, keto- or esther-form. The influence of nitric acid, nitrates and other ions on the extraction of uranium with ethyl eth er has been described2. Following chromatographic data3, we investigated the extraction of uranyl nitrate with tetrahydrosylvane (THS) and tetrahydro-pyrane (THP) . The results of these experim ents are briefly described in this pa,per and compared with those obtained using ethyl ether and ethyl acetate. O.S 1M 1.5 2N 2.5 3N CONC ENTRATI ON OF AMMONIUM NITRATE Fig. I. The extraction data of uranyl nitrate ('l o) plotted against the concentration (N) of ammonium nitrate in the aqueous phase, Solvents: tetrahydrosylvane (THS) , tetrahydropyrane (THP) , ethylacetate (EtAC) and diethylether (Et20). The amount . of uranyl nitrate !mg. U/ 12ml. , the concentration of -nitric acid 0.25 N, and the extraction time 70 minutes. * ContribuUon No. 57 from the Laboratory of Physical Chemistry. 10 I1I. BRANICA, E. BONA, N . S IMUNOVIC AND B. TEZAK Fig. 1. shows how the extraction of uranium with tetrahydrosylvane (THS), tetrahydropyrane (THP), ethyl acetate (EtAc) and diethyl ether (Et20) depends on the concentration of ammonium nitrate in the aqueous phase ; the extraction time (70 min.) and the concentrations of nitric acid (0.25 N) and of uranyl nirtrate (1 mg. U/12 ml.) were kept constant. The best extraction medium seems to be the THS. The salting out effect of ammonium nitrate is less pronounced with ethyl acetate and diethyl ether; 100 percent extraction was obtained with THS and THP at 0.8 N and 1.2 N ammonium nitrate respectively. Et~O D. 0.1 0.3N 0.6N O.llN CONCENTRATION OF NITRIC ACID Fig. 2. The extraction data of uranyl nitrate ('lo) plotted against the concentration (N) of nitric acid in the aqueous phase . Solvents: tetrahydrosy lvane (THS), tetrahydropyrane (THP), ethyl-acetate (EtAc) and diethylether (Et20) . The amount of uranyl nitrate lmg.U/12 ml., the con-centration of ammonium nitrate 0,8 N, the extraction time 70 minutes. '1.JOr-----r r~-x I I\ I I \ THS I \ I I \ I I \ I I \ ·~ I I \ / I I v \ I I \ I I \ I z <! ~ 01 .). I I 1j ::: '" " ' " ' 0 z 0 t-u <( a:: I-x w COMPOSITION OF THE SYSTEM 3 z z 0 4 2 a:: 1-z w u z 0 u ~ .?... 50 ::?: :::> z <( a:: :::> ~ 0 z 0 ,_ ~ 1- n I I 1 ~ ); COMPOSITION OF THE SYSTEM 3 z z 0 ~ 2~ z w u z 0 u Fig. 3. and 4. The extraction data of uranyl nitrate ( 'io) for different comp )sitions of the aqueous phase. Solvents: tetrahydrosylvane (THS in Fig. 3.) and tetrahydropyrane (THP in F ig. 4.). The amount of uranyl nitrate was lmg.U/12 ml., the extraction 70 minutes. EXTRACTION OF URANYL NITRATE WITH ORGANIC SOLVENTS 11 The change of the extractibility of uranyl nitrate by THS, THP, EtAc and Et"O, with the concentration of nitric acid is given in Fig. 2. The concentrations -0f ammonium nitrate (0.8 N) and uranyl nitrate (1 mg. U/12 ml.) , and the .extraction time (70 min.) being consrtant. It seems that a complete extraction of urany l nitrate with EtAc and Et~O is impossible under these conditions. To obtain a 100 percent extraction of uranyl nitrate (in 70 min.) - in th e concentration range from 12 [J.g. to 180 mg, of uranium per 12 ml. - it is thus necessary to perform the extraction with THS in presence of 0.8 N ammonium nitrate and 0.1 N nitric acid, or with THP in p resence of 1.2 N ammonium nitrate and 0.25 N nitric acid. The influence of various impurities in the aqueous phase on the extraction -of uranyl nitrate with THS and THP is shown diagramatically in Figs. 3. and -4. The inhibitory effect of phosphate ions is very pronounced; the chlorides .and sulfates act in the same way but their effect is weaker. To remove inhibitory effect of these ions we added calcium- and fe rric- nitrate. Calcium nitrate was without effect , while ferric nitrate enabled the extraction of uranyl nitrate in presence of phosphate- chloride- and sulfate- ions. The precipitate of uranyl nitrate w1th phosphate-ions is soluble in ferric n itrate solution, w hereas calcium nitrate itself was precipi:tated with phosphate-icns. The mixture of ammoniumphosphate (0.1 N) , -chloride (0.05 N) and -sulfate (0.1 N) , with uranyl nitrate (1 mg. U/12 ml.), ferric nitrate (0 .6 N) and calcium nitrate (0.4 N) is a clea r solution, from which uranyl nitrate can be easily .extracted. EXPERIMENT AL An automatic micrnextractor, was u sed for continuou s extraction of uranyl 11itrate. There were always 12 ml. o;f aqueous ;phase in the contacting vessels (thl? vessels were 12 cm. high and 1.4 cm. in diameter) ; the organic solvent layer was 1 cm. high. The circulation rate of the solvent was about 1 ml./min. (2.6-3.5 drops/ sec.) for THS and THP ; iit was much greater for EtAc and Et20 ; the heating con-ditions were always the same. For each extraction 6-8 ml. of solvent were used. After the extraction was finished and the solvent evaporated, the residue (probably a polymerisate of THS or THP) , was destroyed by heating on an air-bath; 2 X 0.5 ml. of redistilled nitric acid (15 N) were carefully added, followed by 2-3 X 1 ml. 300/o H20 2, and evaporated nearly to dryness each time. Finally 0.5 ml. perchloric acid (700/o) were added to remove nitrate-ions and change uranium into six-valent state. The residue was dissolved in the supporting electrolyte (0.160/o salicylic acid, D.0090/o thymol and 0.40/o v/v sulphuric acid) and uranium determined polarogra-phically5, Cambridge Pen- recording Type polarograph was used ; the results are given percentages (the ratio of the diffusion currents Qof the sample to that of the standard). Tetrahydrosylvane and tetrahydropyrane were synthesized in the Institute for Industrial Research, Zagreb. Ethyl acetate and nitric acid were redi'stilled. All other chemicals were of analytical grade purity. Acknowledgment. This work vvas performed in the Institute for Medical Re-search, Yugoslav Academy of Science and Arts, Zagreb, and we want to express our thanks for the assistance during our e~periments. We are also greatly indebted to Mr. I. Brihta, head of the Division for Organi l( Syntheses -of the Institute for Industrial Research, Zagreb, for the synthesis of .solvents used in this work. 12 M. BRANICA, E . BONA, N. SIMUNOVIC AND B. TEZAK REFERENCES l. H. N. Irving, Quart. Revs. (London) 5 (1951) 200. 2. A. Nostro m and L. G. Si 11 en, Svensk Kem. Tidskr. 60 (1948) 227; C. J . Roden, Anal. Chem. of Manhattan Project, New York 19·50. 3. T. V. Arden, F. H. Burst a 11 a nd R. P. Lins tea d , J. Chem. Soc. 1949 (Suppl. Issue, No. 2.) S 311. 4. M. Bran i c a, Arhiv kem. 26 (1954) 119. 5. V. B . Vo u k, M. Bran i c a and 0. A. Weber, Arhiv kem. 25 (1953) 225. IZVOD Ekstrakcija anorganskih iona organskim otapalima. I. Kontinuirana ekstrakcija uranil nitrata tetrahidrosilvanom i tetrahidropiranom M. Branica, E. Bona, N. Simunovic i B. Tefok Ispitivana je ekstrakcija uranil nitrata, tetrahidrosilvanom (THS) i tetrahidro-piranom (THP) u usporedbi prema etilacetatu (EtAc.) i dietileteru (Et/ )) , u automat-skom mikroekstrakto.ru4. Istrazivan je utjecaj amoniumnitrata i dusicne kiseline na ekstrakciju uranilnitrata, nepovoljan utjeca j amonium-sulfata, -klorida i -fosfata kao i sprecavanje tih pojava kalcium i fer i nitratom. Uz umjerene uvjete potrebno je 70 minuta za postizavanje kvantitativne ekstrakcije uranilii.itrata (od 12 .ug do 180 mg urana/12 ml) tetrahidrosilvanom i tetrahidropiranom, dok se to ne maze posUCi etilacetatom i dietileterom. Odredivanja urana vrsena su polarografskom metodom5. INSTITUT »RUDER BOSKOVI C:«, ZAGREB i FIZICKO-KEMIJSKI INSTITUT PRIRODOSLOVNO-MATEMATICKI FAKULTET ZAGREB Primljeno 31. decembra 1955. 

Extraction of Inorganic Ions with Organic Solvents. I. Continuous Extraction of Uranyl Nitrate with Tetrahydrosylvane and Tetrahydropyrane

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