SCIENCE CHRONICLE

A L L - U N I O N CONFERENCE ON R A D I O C H E M [ S T R Y

Rad[ochclnlcal research has assumed large proportions 1, die Soviet Union. In order to prbvlde an oppoc- tun[~ for the discussion of the main problemsof radiochemlstry and the dlfect[ons in which this science Is do- veloping, an All-Union Conference was called for March 195'/in Lent.grad. Abo.t six hundred scientific workers from various cities of our country" took part in dzis conference. [n die fifty papers ]xcse.zad at the con ~ ferunce, the maln probE:ms of theoretical radiochemisuy and dzc chcrnistsy of certain radioactive elements wer~ considered. The topics included the forms in wls[ch small amounts of radloacUve substances exist $n solu- Uons and solids, dlelr behavior when co?.ecip[tatcd with carrlt:rs, the laws of dlsLrlbution between two immis- cible igzascs, thu chem[stxy of tcchnc:tium, pros.ethium, and the [ransplutonJc elcme.ts (arr~erlclum, curium. berkeLiun,, califondum, etc.).

"['lle invcsUgadon of the state of radio elements in dil.te sol.tlon and their behavior when r with crystalline ixcclp[tates constltutu the cenzxal problem of radiochcnd'.uy, on which Soviet scienUsts have been working sl.ce 1924 (V.G. Khlopln's school). The experimental material presented showed that work on this problem has developed successfully and has resulted in the necessity of re-examining some of the earlier views. As a n:sult of numerous uxperimcutal invcsUgaL[ons, I.E. 5tarik and co~-workcrs es'zablished the existence of true collolds in die cas~ of substances Ixcscnt [n solution at high dilution. This result confirms the view. which wa~ for a long'Urnc rejected, that radioactive substances found In nature in extremely low amount form true colloidal solutlens when the solubility product has been attalned. It was shown, moreover, that by a corn o binar.ion of various nlethods of [nvestisating colloidal solutions it is posslble to determine unequivocally die ]xoporUon of a substa.ce Present In solution, both in the ionized state, and also as true colloids or pseudocof loids.

.~:veraI Investigators presented int,:resting data on the leaching of daughtL:r radloacUve substances from minerals and artificial salts, and hypotheses were advanced co.cernlng th�9 form in which radlo..clements are Pre~nt In solids (I.E. Starik and co-workerl, V.I. Baranov, K.V. Zaberenko and co-workers).

New theo~dral and experimcnta! results were obtal.ed on d~ ccpr~r of radio elcmenu with crystal!ine Precipitates. $~veral exalnples wcz~ given w show ,~Itat anomJ'" �9 "nl~d crystals are subject m laws that were ix�9 cotisldured to be valid only for true mixed :,fstals (V.L Orebenshch[kova. E.~.L Ioffe). It follows that the merited, used both h~:re and abroad, of [somorphous coprecipitation for die detennl,adoa of valency In substances present in sol, lion in extremely smallamountsnJay sometimes lead to Incorrect concht- slum. VoN. Dohrova pollltud out that the n~:cha,lsm of enurah,n)ent depends not only on experimental condi- tions, as was considered [xevlously, but also on die Ixoputties of the macrocomponent.

Values of crystallization coefficients obtah~d by the classical inethods of V.G. Khlopin have been util- Ized in nlany systems for dte Improvement Of the technology of preparing pure reagents (G.L Gorshteln).

From the paper of N.A. Rudn~v and A.A. Bragina on die coprcclp[tation of thallium and gallium with sulfides it may be Inferred that the mechanism of entrainment is very complex and depends on the namns Of the adsorbent and the character of thu aging of die [xec[p[tates.

A.A. Gt[nberg, In' a paper on die [inportance of complex compounds f~r radiochcmlsuy, examined the sigrdficance of complex-formation for tho d~tailed drscriprdon of ~ e statu of radio-~lem~nt Ions in solution. TIle part played by complox formation In [xocesses of cocrystalUzat|on of radio elements with cxystallino [xe~ cipltates In dieir isola~on from solutions a.d melts was noted for the fi~t time (V.I. Grebenshchlkova and E.M. Ioffu for solutions; V.R. KE)kman fm n~lu) .

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A.A. Grinl~rg pointed out that a cr i t ical aoaly~is of data obtain,:d in dze study of anomalous mixed crys- u l r suggests that cite ]x'~:~tlc'~ of con)p:ux iota in soStHon may sometimes provide tim explanation of dm ab- scfl~: o f a k~wcr l imi t of miscibil i ty. ILV. 6ryzgalova pointed out tltat by dcrurmining crystalUzatlon cocff i- drnt.~ alp: may cstablidl the nli:ziz~mln conocntration of complex former at which complex ions begin to I~. ro~d [r~m ~bstanc~s pcusmr in soluClml Its amomtrs ~ luctabl r by an Impulse counter.

confezeno~ discu.~d .~vrral lxoblonts conocrl~cd widm the application of adsorption processes In dl�9 ixactio=. In the papers and discussious on dds topic the ruml~ of experimental and dleoredcal In- l~sdgattons on the following questions w~:rc prr

l . Theory of ion excha,gc (Dapcr by B.P. NikoLd~).

2. Chn)matographic separation or rare earth and trnnsuranic clcments (paints by N.N. Tunitsky, B.K. I~:obraT]tensky. M.~,L Sm,yavin. V.B. [~dov. ^.K. Lavrukh[~la and co-workers, and others).

3. Determination of the staz~ of r a t a clvn)unts in solution by the m~thod of adsorption on glass and on ion..cxchangv resins (papers by A.V. Ko~ir~yn. V.L Paramonova and co-work~rs. Yu.B..GcrHt. A.N. Subbotina. and othen).

4. Selective a~orption of sotwc radio ~luineqts on ion-exchange pJsins. ~ silica gel, and o~cr porous ad- sof t .n i t (B.P. Niko]sk)- and co-worker~. D.N. SLrazhesko).

[~ the papt:rs on fit,: chromatography of raru.-r e!~mcnts, the main attention was devoted to the the- oretical and cxperin~:ntal basis for the rapid separation of th~ rar~ ~arth products of u,clear reactiom. The remit= reported at the confr indicate that i t b possible to s~param two rare.~:arth elcmcuts completely In the space of five minutes (B.IC Prcobrazhensky). A theoretical equation was propo~cd (N.N. TuniL~kT) for dr t~rminlng d~ minilnum drr~ rcquirud for the separation of two rarc~arth r

V.M. Vdovenko read a review paper untiOed "Extraction Processes [o the Study and ,%paratiolt of Rad[o- Ek:nr~:qts." Extraction Is used extensively in radiochcmical investigations, so dlat the stltdy of processes of ex- rractin~ the elements has acquired special importance. Co~ltributions on the fl~corctical and r in- ~sttgat ton of extraction ixoccs~es were mack: by dze following: A.V. Nikolacv - o b t a i , i n g weighable amounts of cerium by ex~action of Cc 4~" with ~iburyi phosphate; i.A. Rcformatslry and M.N. Ryzhov -r o~ americium and curium with tributyl phosphate= and aim A.M. RorJ:n.

V.M. Vdovenko, LN . Lazarev. A.A. LIpovsky and M.G. Kuzina reported the preparation or aniline uranyl lxlac~tatr In the form of which uranium can I~ cxlractcd with certain organic solvents. Taking the example of d~e distribution of uranyi nitrate between ",queous nitr ic acid and dibutyl ether, they showed that d,= forma- tion of complex compoue,ds has a very im]x,rtaur effect on the cxtrac~on of radio el~n-,~nts.

In d~ examination or the chcmic:,i properties or ii~dividual radio elements, the greatest interest and the most Uvr discussions were arou,~d by th~ papers o=1 flw chemistry of technetium and americium. V.L Spitsyn and A.F. Kuzina detailJd the ixoc~dure rot obtainizlg weighable amotmts of technetium. Yu.B. Gcrlit described the behavior of technetium lo~ls in. various valency states in acid. neutral and alkaUr~ n~dia.

in a review of the: c]zcndstry or americium, G.N. Yakovicv discussed methods or obtaining appreciabl~. ~ lghab l= amounts or Am =4z andAm ~= at~d the futort: [xos[:x:cts in this field, lit charact~:rizcd the valunc,/ status of the �9 and d~scribed m~:dmds of separati,tg an~r[cium from uansplutoulc and ra~..r e]e- menB. He mcndor~d that z,~mricium has I~en studied enore thoroughly thau some long-known elumentl.

A.G. Rykov and A.A. Zait~:v reported their ruce~tt remits on die reduction of Am v and Am V| by the tadiolysb products of water subjected to rile a-radlaflo== of Am z4t. As a ~sult of an investigation of the Idn- cz/cs o~ these reactions. [t was shown that dz~:r~ is a relationship between the radiational yield of the reducing radlolysb products from water and the cunc~ntration of sulfate ions. A substa,~tial diffcrcnc~ was noted between the rates o1' r�9 ruactiofls Of Aln V and Am VI.

Interesting r~suhs on the dtromatograpl~ic r~paration of bcrkuliwn and californium were lepr t~d by K.V. FlUppova and L L Guava. TI~y obtained zh= best ~eparation whr=z they used ammonium hydroxy[sobutyrata as �9

confi:r=nc~ p a ~ d a resol;~tion on the directions of further inv~stlgat[r in ~adlochemistty, and f l~

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question of the publlca[[on of a six:clal Journal "Radiochemllsl~7'* was ra|sed. Part of d~e poceed|nss of the etmferunce will be l~ubll~icd in Inmganir Chemistry.

V.L C, mbenshddkova and A.M. Troflmov

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