CA2180682A1 - Succinic acid derivative degradable chelants, uses and compositions thereof - Google Patents

Abstract

Polyamino disuccinic acids are effective chelants for use in gas conditioning (preferably involving the poly-amino disuccinic acid in the form of a metal, preferably an iron complex). The copper chelates are also useful in electroless copper plating. In electroless deposition, the invention includes a method of electroless deposition of copper upon a non-metallic surface receptive to the deposited copper including a step of contacting the non-metallic surface with an aqueous solution comprising a soluble copper salt and a polyamino disuccinic acid and plating baths appropriate for such use. Another aspect of the invention includes a method for removing iron oxide deposits from a surface including a step of contacting the deposits with a solution comprising an ammoniated polyamino disuccinic acid. Yet another aspect of the invention involves gas conditioning including a process of removing H2S from a fluid comprising contacting said fluid with an aqueous solution at a pH suitable for removing H2S
wherein said solution contains at least one higher valence polyvalent metal chelate of a polyamino disuccinic acid and a process of removing NOx from a fluid comprising contacting the fluid with an aqueous solution of at least one lower valence state polyvalent metal chelate of a polyamino disuccinic acid.

Description

.~ 21 80682 This application i5 a divisional application of appLication No. 2,160,701 filed on May 20, 1994.
The invention of the parent application relates to chelants, particularly uses of certain degradable chelants in photography. The divisional application relates to the use of polyamino disucclnic acid chelants and their uses for such things as plating copper, removing iron deposits or producing iron complexes. Polyvalent metal chelates of polyamino disuccinic acia may be used to remove such compounds as 1~2S or NOX from fluids.
Chelants or chelating agents are compounds which form coordinate covalent bonds with a metal ion to form chelates. Chelates are coordination compounds ln which a central metal atom is bonded to two or more other atoms in at least one other molecule or ion (called ligand) such that at least one heterocyclic ring is formed with the meta~ atom as part of each ring.
Chelants are used in a variety of applications including food processing, soaps, detergents, cleaning products, personal care products, pharmaceuticals, pulp and paper processing, water treatment, metalworking and metal plating solutions, textile processing solutions, fertilizers, animal feeds, herbicides, rubber and polymer chemistry, photof inishing, and oil f ield chemistry . Some of these activities result in chelants entering the environment. For instance, agricultural uses or detergent uses may result in measurable quantities of the chelants being in water, It is, therefore, desirable that chelants degrade after use.

2 1 80682 .~
~ lodegradablllty, that i5 ~u~cePtlblllty to degradatlon by mlcrobes, 18 partlcularly useul because the mlcrobes are generally nRturally present ln envlronments lnto whlch the chelants may be introduced. Commonly used chelants llke EDTA ~ethyl~ne~l1AmlnP tetraacetlc acld) are blodegradable, but at rates somewhat slower and under condltlons consldered by some to be less than optlmum. (See, Tled~e, "Mlcroblal Degradatlon of Ethyl~n~ m1n~ tetraacetate ln Solls and Sedlments," Applled Mlcroblology, Aug. 1975, pp. 327-329). It would be deslrable to have a chelatlng agent whlch degrades faster than EDTA or other commonly used che lant 8 .
Whlle degradatlon of the chelant compounds themselves 18 an lmportant factor ln ascertalnlng thelr fate ln the envlronment, lt 18 also lmportant to conslder the form(s) ln whlch the c~ ~nri ls llkely to be found ln a natural envlronment llke a lake, rlver or soll. In contact wlth such envlronments, chelants can frequently be expected to be ln the form of thelr chelates wlth .. .. .

WO 94/28464 2 1 8 3 6 8 2 PCTI~IS94/0~/4 metals present in the environment or meta~s acquired in use of the chelant.
The specific metal chelated depends on the metals present, their relative ~,UI~C~ ldliV~Is and availability, and the relative affinity (e.g. as ~ ssed by stability constants which can be calculated by c~" If ~dl i"g potentiometric pH
5 measurement of the chelant in the absence of and in the presence of known ~,ollc~ ldliùl~s of metal ion as described in DETERMINATION AND USE OF
STABII ITY CONSTANTS by Martell and l1Opf~oitic~ VCH Publishers, 1985, pp.
14 and 21-27.) of the chelant for each metal present. It is often important thatthe chelant degrade well in the form of its iron, copper, manganese or calcium cu..~f~ It would be desirable for a chelant compound to degrade in the fomm(s) ft is most likely to be found in the environment. This form is cullllllul)ly the iron complex. (See, i aurent et al., IVL Report, ~Effect of Complex Formers on the Aquatic Environment, NTA, EDTA and DTPA~, Inst. Water and Air Conservation Research (IVL), Stockholm, Pub. B921, Dec. 1g88.
Some chelants are at least su",~ ,dl iJiod~yld~dbl~, but have other disadvantages that reduce their suitability for ~ s Shat may result in their presence in water.
20 Polyamino disuccinic acids have been l~.. oy"i~d as having some chelating properties but have not received wide usage. For instance, a better known member of the family, namely ethyl~"~Lid", ~e disuccinic acid (EDDS), has not been widely used because it has less ability to chelate certain metal ions such as calcium and magnesium than more widely used chelants. The 25 fJlt~fJdldl;vll ûf polyamino disuccinic acids is discussed by Kezerian et al. in U.S. Patent 3,1Ci8,635 where their use in rust removal is disclosed. Atkinson inU.S. Patent 4,7û4,233 disclose use of EDDS in d~t~ly~llt~ to enhance removal of organic stains and mention its i,' ~tc~ Y~
i3iVdt:yld~dliUI~ is of particular interest in pllUtV~U,ldf~l~y, but finding a c~""~" '~y useful i iud~yld.~ chelant has been difficuit. Chelates are particularly useful in the fJI Iulvu~l d~ u industry as iron cul llfJltu~:s used as oxidizing agents, cûmmonly referred to as bleaching agents, fûr removing silver halide images. However, the chelating agents that are most useful do not J~r,fl'5,f ~ f-' in a desirable time (e.g. ethyi~l~e~iid~ l dac~ . acid, N-hydroxyethylethlyenediaminetriacetic acid, diethylenetriaminepentaacetic acid, cyclohexanedlamlnetetraacetlc acid, end propoylon~ m1ne-tetraacetlc acld all blodegrade less than 80~ ln 28 days uslng the semlcontlnuous actlvated sludge test.
Che lat lng ab l l lt y 18 not lnd lcat lve of redox abl l lt y of chelates of metal lons capable of more than one valence state. Nor can redox ablllty be predlcted from structure as explalned by R. Wlchmann et al ln "A New Bleachlng Agent,"
presented at Imaglng Sclence and Technology ' g 7th Internatlonal Symposlum on l?hotoflnlshlng Technology, and publl~hed ln R. Wlchmann et al. "AdvAnce Prlntlng of Paper Summarles7 Seventh InternAtlonal Symposlum on Photoflnlshlng Technology," Las Vegas, NV, February 3-5, 1992 pp. 12-14.
It would be deslrable to have a chelant useful ln photographlc processes and ln other redox appllcatlons, partlcularly as a bleachlng agent ln photography, which chelant 18 greater than 80 percent blodegradeble wlthln less than 2E days accordlng to the semlcontlnuou~ Actlvated sludge test (ASTM D-2667-82~.
In the lnventlon of the parent appllcatlon the ferrlc chelates of polyamlno dlsucclnlc aclds such as EDDS
have been found to be excellent oxldlzlng agents for use ln photographlc bleach, bleach-flxlng solutlons for the bleachlng of photographlc sllver.
In one aspect, the lnvent lon of the parent appllcatlon lncludes a method of bleachlng or bleach-flxlng a photographlc materlal whlch comprlses contactlng sald materlal wlth a bleachlng solut lon contalnlng a bleachlng agent comprlslng a ferrlc complex of a polyamlno dlsucclnlc acld.

21 80682 ::
.~
This lnventlon of the p~rent Qppllcatlon lncludes the use of a ferrlc complex of a polyamlno dlsucclnlc acld ln bleachlng or bleach-flxlng Q photographlc materlal. Addltlonally, the lnventlon of the parent appllcatlon lncludes ~n aqueous photographlc bleachlng solutlon comprlslng a water-soluble hallde and as the bleachlng agent a ferrlc comple~ of a polyamlno dlsucclnlc ecld.
The lnventlon of the dlvlslonal appllcatlon lncludes methods of electroless platlng uslng varlous metals, especlally copper. It lncludes a method of electroless deposltlon of copper upon a non-metalllc surface receptlve to the deposlted copper characterlzed ln that the non-metalllc surface 18 contacted wlth an aqueous solutlon comprlslng a soluble copper salt and a polyamlno dlsucclnlc acld. Also lncluded 18 a method of electroless copper platlng whlch comprlses lmmerslng a receptlve surface to be plated ln an alkallne, autocatalytlc copper bath comprlslng water, a water soluble copper salt, and a polyamlno dlsucclnlc acld complexlng agent for cuprlc lon. Addltlonally, there 18 an 2~ lmpluv~ - 1 ln a process for platlng copper on non-metalllc surfaces, only selected portlons of whlch have been pretreated for the receptlon of electroless copper, by lmmerslng the surface ln an autocatalytlc alkallne aqueous solutlon comprlslng, ln proportlons cap~ble of effectlng electroless deposltlon of copper, a water soluble copper salt, a complexlng agent for cuprlc lon, and ~ reduclng agent for cuprlc lon, the lmpluv. ~ comprlslng uslng as the complexlng :

2 ~ 8G682 agent for cupric lon, a polyamlno dlsucclnic acld. The lnventlon lncludes a bath for the electroleR~ platlng of copper characterlzed in that, a polyamlno dl~ucclnlc acld 18 used as complexlng agent f or cuprlc lons .
Another aspect of the lnventlon of the dlvlslonal appllcatlon lncludes A method for removlng lron oxlde depo31ts from a surface characterlzed ln that the deposits are contacted wlth a solutlon comprlslng an ammonlated polyamlno dlsucclnlc acld.
Yet another aspect of the lnventlon of the dlvlslonal appllcatlon lnvolves gas condltlonlng. In thls aspect the lnvent lon lncludes a method of removlng H2S f rom a fluld comprlslng contactlng sald fluld wlth an aqueous solutlon at a pH sultable for removlng H2S characterlzed ln that sald solutlon contalns at least one hlgher valence polyvalent metal chelate of a polyQmlno dlsucclnlc acld.
Another aspect o~ the gas condlt lonlng lnvent lon lncludes a method of removlng N0x from a fluld characterlzed ln that the fluld 1~ contacted wlth an agueous solutlon of at least one lower valence state polyvalent metal chelate of a polyamlno dlsuccclnlc acld.
A ~urther ~pect of the dlvlslonal appllcatlon comprlses a process for produclng an lron complex of a polyamlno dlsucclnlc acld comprlslng reactlng a polyamlne dlsucclnlc acld (1) wlth ammonla or sn alkall metal hydroxlde selected from sodlum, potasslum or llthlum, and 4a ~ 2 1 80682 ( 11 ) an lron salt or lron oxlde ln an aqueous medlum to glve a correspondlng polyamlno dlsucclnlc acid lron ammonlum or alkall metal salt.
Polyamlno dlsucclnlc aclds are compounds havlng at least two amine groups to of at least two of whlch 18 attached a succlnlc acld (or salt ) group, preferably only two nltrogen atoms each have one succlnlc acld (or salt ) group attached thereto That 18, the compounds have at least two nitrogen atoms to whlch a succlnlc acld or salt group 18 attached and may optlonally have addltlonal nltrogen atoms wlth or wlthout succlnlc groups. The compound has at least 2 nltrogen atoms, and due to the commerclal avallablllty o~ the amlne, 4b --WO 94/~}4W 2 1 ~ 0 6 8 2 PCTIUS94105~14 preferably has no more than 10 nitrogen atoms, more preferably no more than 6, most preferably 2 nitrogen atoms. Preferably no more thah 4 nitrogen atoms, more preferably no more than 3, most preferably 2 nitrogen atoms are s~lhctitl~tPd with succinic acid groups. Remaining nitrogen atoms most 5 preferably are s~Jhstit~!to~l with hydrogen atoms. More preferably, the succinic acid groups are on temminal nitrogen atoms, most preferably each of which nitrogens also has a hydrogen substituent. Because of steric hindrance of two succinic groups on one nitrogen, it is preferred that each nitrogen having a succinic group has only one such group. Remaining bonds on nitrogens having a succinic acid group are preferably filled by hydrogens or alkyl or alkylene groups (linear, branched or cyclic including cyclic structures joining more than one nitrogen atom or more than one bond of a single nitrogen atom, preferably linear) or such groups having ether or thioether linkages, all of preferably from 1 to 10 carbon atoms, more preferabiy from 1 to 6, most preferably from 1 to 3 carbon atoms, but most preferably hydrogen. More preferably, the nitrogen atoms are linked by alkylene groups, preferably each of from 2 to 12 carbon atoms, more preferably from 2 to 10 carbon atoms, even more preferably from 2 to 8, most preferably from 2 to 6 carbon atoms.
The poly~_...;"~ disuccinic acid compound preferably has at least 10 carbon 20 atoms and preferably has at most ~0, more preferably at most 40, most preferably at most 30 carbon atoms. The temm succinic acid- is used herein for the acid and salts thereof; the salts include metal cation (e.g. pot~csi~
sodium) and ammonium or amine saits. Polyamino disuccinic acids useful in the practice of the invention are unsl~hct~ (preferably) or inertly 2s 5llhs~ d~ that is s~hstitl~tPd wXh groups that do not undesirably interfere with the activity of the polyamino disuccinic acid in a selected ~, " "
particularly ~JIIOtuyld~Jl)i~, uses. Such inert substitutents include but are not limited to alkyl groups (~l~r~:laL,!y of from 1 to 6 carbon atoms); and aryl groups including arylalkyl and alkylaryl groups (~ r~- dbly of from 6 to 12 carbon

3~ atoms), with alkyl groups preferred among these and methyl and ethyl groups preferred among alkyl groups. Inert substituents are suitably on any portion of the molecule, preferably on carbon atoms, more preferably on alkylene groups, for example alkylene groups between nitrogen atoms or between carboxylic acid groups, most preferably on alkylene groups between nitrogen groups.

~ 2 l 80682 Pre~erred polyelmlno dl~ucclnlc aclds lnclude ethylPne~ m1ne N,N'-dlsucclnlc acld, dlethylenetrlamlne N,N"-dlsucclnlc acld, trlethylenetetraamlne N,N"'-dlsucclnlc acld, 1,6-hexamethylenPdl~m1n~ N,N'-dlsucclnlc acld, tetra-ethylenepentamlne N,N""-dlsucclnlc acld, 2-hydroxypropylene-1,3-dlamlne N,N'-dlsucclnlc acld, 1~2-propylpn~ pm1ne N,N'-dlsucclnlc acld, 1~3-propyl~n~1Am1np N,N'-dlsucclnlc acld, cls-cycloh~ n~ qm1nG N,N'-dlsucclnlc acld, trans-cyclohexanedlamlne N,N'-dlsucclnlc acld, and ethylenebls-0 ( oxyethylenenlt rllo ) -N, N ' -dlsucclnlc acld .
Such polyamlno dlsucclnlc aclds can be prepared, for lnstance, by the process dlsclosed by Kezerlan et al . ln U. S .
Patent 3,158,635. Kezerlan et al dlsclose reactlng malelc anhydrlde ~or ester or salt ) wlth a polyamlne corr~Rrnn~lln~ to the deslred polyamlno dlsucclnlc acld under alkallne condltlons. The reactlon ylelds a number of optlcal lsomers, for example, the reactlon of ethylenedlamlne wlth m~lelc anhydrlde ylelds a mlxture of three optlcal lsomers [R,R], [S,S~ and [S,R] ethyl~n~ qmlne dlsucclnlc aclds (EDDS) because there are two asymmetrlc carbon atoms ln et~lylenedlamlne dlsucclnlc acld. These mlxtures are used as mlxtures or alternatively separated by means wlthln the state of the art to obtaln the deslred lsomer(s). Alternatlvely [S,S~ lsomers are prepared bY reactlon of such aclds as L-aspartlc acld wlth such ~ ds 28 1, 2-dlbromoethane as descrlbed by Neal and Rose, "8tereospeclflc Llgands and Thelr Complexes of E~thylen~ m1n~1Rucclnlc Acld", InP~alllc Chemls~ry, v.7. (1968), pp. 2405-2gl2.

7J,069-198 ~ 2 1 80682 The ~nvent lons includes use of lron complexes of polyamlno dlsucclnlc aclds such as ethyl~ne~ m~ n~ dl3ucclnlc acld (~DDS), especlally ln photography, The ferrlc complexes are also useful ln abatement of hydrogen sulf lde and other acld gases and Q8 a source of lron ln plant nutritlon.
Slmllarly Otner rnetal complexe3 such as the copper, zlnc and manganese complexes supply those trace metals ln plant nutrltlon. The ferrous complexes are useful ln nltrogen oxlde abat ement .
Iron complexes of polyamlno dlsucclnlc acld are convenlently formed by mlxlng an lron compound wlth an aqueous solutlon of the polyamlno dlsucclnlc acld (or sAlt ? . The pE~
of the resultlng lron chelate solutlon 15 preferably 7406g-lg8 .

WO 94128464 2 i 8 0 6 8 2 PCT/US91/05674 adiusted with an alkaline material such as ammonia solution. sodium carbonate, or dilute caustic (NaOH). Water soluble iron compounds are conveniently used. E%emplary iron compounds include iron nitrate, iron sulfate, and iron chloride. The ~inal pH of the iron chelate solution is preferably in the range of 4 to 9, more preferably in the range of 5 to 8. When an insoluble iron source is used, such as iron oxide, then the polyamino disuccinicacid is preferably heated with the iron oxide in an aqueous medium at an acidic pH. The use of an ammoniated polyamino disuccinic acid solution is particularly effective. A,l,l.lu.~ia~d polyamino disuccinic acid chelants are conveniently formed by combining ammonium or aqueous ammonia solutions and aqueous solutions or slurries of polyamino disuccinic acids in the acid (rather than saK) fomm.
Polyamino disuccinic acids are eflective as chelants especially for metals such as iron and copper. Effectiveness as a chelant is conveniently measured by cun~lt Ai, ~g the chelant with a metal such as copper such as by mixing an aqueous solution of known Cùl~C~Illldtic,l) of the chelant with an aqueous solution containing copper (il) ions of known Collc~lllldli~" and measuring chelation capacity by titrating the chelant with copper in the presence of an indicator dye, using as an endpoint detector a 1.l ,utu~t:, Isilive electrode.
Chelating capac'lty is not, however, a direct indicator of effectiveness in activities such as bleach fixing solutions for ~JI lu~vyldpl ,y. For instance, N-methyli."i, ~odiac~li,; acid (MIDA) is a relatively poor cheiating agent for ferric iron, requiring 2 to 3 moles of chelant to complex and solublize one mole of iron. The ferric comple% of MIDA, however, is a strong bleaching agent.
~ II,,~i~"e--lid",il~e disuccinic acid is i~i~)d~Vld id~l~ using a sldl~ddl ii~d testsuchasASTMD-2667-82. Inthattest,a~ld~dd~Lii tt~isludgecul,h:.lill~
municipal waste treatment plant Ul yd"is",s is used to ~i~d~VI~ i~ the chelant in the presence of metal ions l~ llldliVe of those found in the ~ i,ù"l,l~"~
including iron. Such a test simulates the environment encountered in a m unicipal waste treatment plant for screening the inherent biud~vl ~ y of non-volatile, water-soluble compounds. EDDS in this test was found to be greater than 80 percent Lio~ieylddd~l~ in less thar~ 28 days.

-- WO 94/28464 2 1 8 a 6 8 2 PCT/US94/1l_.,/4 Polyamino disuccinic acids are preferably employed in the form of water-soluble saits, notably alkali metal saits, ammonium salts, or alkyl ammonium saits. The alkali metal salts can involve one or a mixture of aikali 5 metal saits aithough the potassium or sodium saits, especially the partial or complete sodium saits of the acids are preferred because of their relatively lowcost and enhanced effectiveness.
Polyamino disuccinic acids are particularly useful in pllutoyld,ully, o especially as a bleaching agent in bleach fixing solutions in the fomm of their iron (Ill) c~ s. The solutions are used to bleach a ~ iuyldphi~ material preferably having at least one silver halide layer or cu~pù,~
Polyamino disuccinic acids used as bleaching agents which are 15 Cu~ . of the bleaching cu,,~p~,;liu,,s and bleach-fixing cu,,,~,osiliù,~s of this invention are preferably utilized in the fomm of water-soluble salts, such as ammonium or alkali metal saits, of a ferric polyamino disuccinic acid complex.
Aiternatively, the ferric complex of the present invention is used as free acid (hydrogen), alkali metal sait such as sodium sait, potassium salt, lithium salt, or 20 ammonium sait. or a water soluble amine sait such as ll i~ a~ lulal 1 l;l ~e sait.
Preferably, the potassium saH, sodium sait or ammonium sait is used. It is optional to use the ferric complex in cu" ,u;l IdliO~l with one more ~IIIil~U)JOIy~ClliJU~ . compounds.
The amount of polyamino disuccinic acid to be used depends on the amount of silver and the silver halide .,~," ,~,os;l.. 1~ in the light-sensitive material to be ~-,ucessed. It is preferred to employ û.ûl mole or more, more preferably û.05 to 1.0 mole, per liter of solution employed; preferably there is a molar ratio of polyamino disuccinic acid to ferric ion of from 1:1 to 5:1. In a ~ .,tdl 30 solution, for supplying a smaller amount of more cul ,~"I, cll~d solution, the solution is conveniently employed at the maximum cu~ dliùn pemmitted by the solubiiity of the polyamino disuccinic acid compound. The bleach ~,~""~osiiiù,~:, of this invention preferably contain 5 to 400 grams per liter of the polyamino disuccinic acid bleaching agent, more preferably 10 to 200 grams 35 per liter.

'0 94128464 2 1 8 0 6 8 2 PCT/IIS9~1O~
The bleach-fixing solution of the present invention is preferably used in a pH range of 2.0 to 10.0, more preferably 3.0 to 9.5, most preferably 4.0 to g.o. The temperature for ~,ucessi,~g is conveniently 80 C or lower, more desirably 55 C or lower, for the purpose of s~ul., ~ssi"g evaporation. The s bleach-fixing ~,u-,essi"~ time is preferably within 8 minutes, more preferably with 6 minutes.
The bleach or bleach-fix c~"")osi~ions optionally contain other additives within the skill in the art, such as amines. sulfites, me,.;d~1u~,ia~ules, alkali metal bromides, alkali metal iodides, thiols and the Ijke. An additional silver halide solYent such as wate~-soluble thiocyanate or potassium thiocyanate is optionally included in the bleach-fix c~ o~it~ . The bleach-fix ~,~",~ositiu"
optionally.also contains a non-chelated salt of an amino,uolj~,d,l,oAylic acid, e.g., sodium salts of EDDS acid, in addition to the ferric saH.
As additives which can contribute to bleach-fixing ~llaldul~ ,s, it is desirable to include alkali metal halides or ammonium halides, such as potassium bromide, sodium bromide. sodium chloride, ammonium bromide, ammonium iodide, sodium iodide, potassium iodide, and the like. Other 20 optional additives include solublizing agents such as triethanolamine, within the skill in the art for use in bleaching solutions such as acetylacetone, u:.~/l Iul lO~drbOXyl;~ acid, pol~p~ ,o~l ,o, i~ acid, organic ~1 los,ul ,o~ acid, oxycdrL,uAyl;~ acid, pOIycd~L,uA~ acid. alkylamines, polyethyleneoxides, and the like.

Use of special bleach-fixing solutions such as a bleach fixing solution cu"",,i:,i"~ a cc.""~o:,itiu,l in which a halide such as potassium bromide is added in a small amount, or aHernatively a bleach-fixing solution in which a halide such as potassium bromide, ammonium bromide and/or ammonium 30 iodide, or potassium iodide is added in a large amount, and, in addition, a bleach-fixing solution with a ~.u,,,posilic.,~ Cu"~ ,i"g a .,c,lllbilldliu,~ of the bleaching agent of the present invention and a large amount of a halide such as potassium bromide is within the scope of the invention.
Silver halide fixing agents suitable for i"~.c",uordliu" in the bleach-fixing solutions of the present invention are preferably compounds within the skill in ..

~ ~VO 94/28464 2 1 ~ 0 6 8 2 pC:l'lUS94/~ 4 the art for fixing p, vl,ds~il ,9 which can react w'~h a silver halide to fomm a water soluble complex, and include thiosulfates such as potassium~thiosulfate, sodium thiosulfate, and ammonium thiosulfate; thiocyanates such as po'~CSj~m thiocyanate, sodium thiocyanate, ammonium Ill;UCYdl~dLt3, thiourea, 5 thioether; highly cullu~ ldldd bromides and iodides. These fixing agents are conveniently used in amounts whhin the range which can be dissolved, namely 5 g/I'der or more, preferably 5û gtlaer or more, more preferably 70 g/laer or more; more preferably there are less than 400, most preferably less than 2û0 grams per laer.
The bleach-fixing solution of the present invention optionally also contains various pH buffers such as boric acid, borax, sodium hydroxide, potassium hydroxide, sodium carbonate, pot~Csillm carbonate, sodium bi~ dl bol ldl~, acetic acid, sodium acetate, and ammonium hydroxide, either singlyorinacu,,,l,i,~d~iu,,oftwoormorecompounds. Optionali,,ylt:dit~
include various fluorescent whitening agents, defoaming agents, antifungal agents, preservatives such as h~nJIuAyldlllil)e, hydrazine, sulfaes, rr~et~hiC~ ~ ~a . bisulf'lte adducts of aldehyde or ketone compounds, or other addaives. Organic solvents such as methanol, dilll~ll.yl;o~ d"~ide, and 20 dimethyl sulfoxide are optionally included. Addaion of a polymer or a copol~.l.dr having a vinyl pyrrolidone nucleus as disclosed in Japanese Provisional Patent Publication No. 10303/1985 is also within the scope of the invention.
Other optional compounds in the bleach-fixing solution of the present invention for a....dl,:,dli"~ bleach-fixing ul~ard.,l~ li~, include l~l~d"..,;~.ylurea, ~I.os,vl~uti~ llia~illloth,'...l-;d~, -cdpl~lldcldl~l, N-methylpyrrolidone, N-tl-"~ e, tetraethyleneglycol ...o.~u,ull~.-yl ether, a~.c,tùllit.il~, and glycol ~u~u~ lllyl ether.
In the ~llutuyld,ul~ ,ù~essi"g method of the present invention, a is preferred that the bleach-fixing step of the present invention is p~, ~u. ".dd i.,.."~.J' ' ~y after color developing, but optiûnally, all~,....ti.l~ly, following ~,~,cessi, .9 such as water washing, or rising or stopping after color developing.
35 Most preferably the bleach-fixing p,~ces~i"g of the present invention is conducted, after pre-fixing p,ucessil~g after color developing.

~'.'0 9~2~4~4 2 1 8 3 6 8 2 I'CI IUS9~/0~1"4 Bleach-fixing p, oc~ ,si"g ~s optionally followed by stabllizing the p,~,essi"g with or without washing with water before or after st-'"' ' ,9 plo~ess;"g. In addition to the lis~ed steps, there are optionally various auxiliary 5 steps such as steps of film hardening, neutralization, black-and-white lv~.;"~, reversal, and washings with a small amount of water, if deslred.
Typical examples o~ preferable l,,.,bes~;"~ methods may Include tlle various steps as shown below:
10 (1 ) Colot developing~Bleach-fix~ng~Water washing (2) Color ci~ ,IV~;I ,g~Bleach-fixing~Washing with a small amount of water ~Water washing (3) Color developing~Bleach-fixing~Water washing~Stabilizing

(4) Color de~r~l.,;,"-g~Bleach-fixing~Stabilking

5 (5) Color developing~Bleach-~ixing~First S' ~ g~Second Stabilking

(6) Color developing~Water washing (or ' ' "' ' )~)~Bleach-~ixing~Water washing (or ' ' "' ' l~)

(7) Color dr,v~lu~i"g~Pre-fixing~Bleach-~ixinQ~Water washing (8~ Color developin~Pre-fixing~Bleach-~ixing~' ' " ' ,~
20 (9) Colordeveloping~Pre-fixing~Bleach-fixing~First ' ' " ' ,g~Second stabilizing ~10) Color dJ J~ ~Stopping~Bleach-fixing~Water washing~
Stabili~ing.
Of these ~ essi~ ~y steps, those of (3), (4), (5), (8) and (9) are preferably employed in the present invention, with ~.,o~es ,;"y steps of (4), (5),

(8) and (g) most preferred.
In the bleach-fixing solution of the lnvent long, chelat lng agent andlor ~erric ~. ." ,~ , thereof outslde the scope of the present invention are optionally added. However, it Is preferred to use the ferric complex outs~de thescope of the present Invention at a proportion of 0.45 mole percent or less relat~ve to the organ~c acid ferric ~UIlllJlt~ 5 of the present Invention.
The reduced product of the ~ron complex formed ~n use of the bleach-fixing solution ~s opt~onally returned to the oxidized state, j~,ef~ by an Il WO 94/28464 2 1 8 0 6 8 2 PCTIUS9410~_ . 4 oxidation treatment. Oxidation l,~dl."a"ts include, for instance, introducin3 air or oxygen bubbles for example into the iJ~ UCtls:,;l ,9 solution irl the bleaching solution tank or the bieach-fixing solution tank, e.g., in an automatic developing machine, or by natural contact of the air on the liquid surface. For oxidation, 5 effective contact of air or oxygen and solution is needed. Such contact is within ths skill in the art and achieved by such means as stirring.
Polyamino disuccinic acids are also useful, for instance, in food products vulnerable to metal-cataly~ed spoilage or ~ ;OlUldtiul~, in cleaning products for removing metal ions, that may reduce the effectiveness, a~d.d,.ce, stability.
rinsibility, bleaching effectiveness, germicidal effectiveness or other property of the cleaning agents; in personal care products iike creams, lotions, deocir~.d,-t:, and ointments to avoid deletrious effects such as metal-catalyzed oxidation, rancidity, turbidity, and reduced shelf-life; in pulp and paper ~,-u..es:,i.lg to enhance or maintain bleaching effectiveness; in pipes, vessels, heat ~I.a~ -a, evproratnrc~ fiiters and other equipment to avoid or remove scaling, in ~JI.d.--.~re~tirAls in metal working; in textile ~ d~dliù.~, desizing, scouring, bleaching, dyeing; in agricuiture as in chelated micronutrients or h~,Li.~ , in pol~ 7Atjnn or ~ ' " . of polymers; in the oil field such as 20 for drilling, production, recovery, hydrogen sulfide abd~t:",a-ll.
The chelants can be used in industrial IJ~vce~ses whenever metal ions such as iron or copper are a nuisance and are to be prevented.
The polyamine disuccinic acids are also useful in ~,, u~esses for the elt l,l. ul~ss ~ p- " ~n of metals such as nickel and copper. Cl~_l- ult~:~s plating is the controlled Al~t ' lyti.; deposition of a continuous film of metal withoutthe assi:,la,~ce of an extemal supply of electrons such as described in U.S.
Patents 3,119,7û9 (Atkinson) and 3,257,215 (Schneble et al.). Non-metallic surfaces are ~,. t t-~dled by means wlthin the skill in the art to make them receptive or Al~t ~ytic for deposition. All or selected portions of a surface are sultably ~ t-t:dt~d. Cu~ Jle~ g agents are used to chelate a metal being deposited and prevent the metal from being ~ ildlt:d from solution (that is as the hydroxide). Chelating a metal renders the metal available to the reducing agent which converts the metal ions to metallic form. Growth of .,l.ul~ss plating can be attributed in part to growth of the ele-,l.u"i~

WO 9412t~464 PCl'lU594/05614 industry, especially for printed citcuits. Cl~_l, u l~:,s plating solutions are complex and contain a variety of il~lddi~ . For example, an illustrative ele~,l,ul~ss copper solution would advantageously contain copper saits, a reducing agent, a material forthe adjustment of the pH, a cu"",ldA;.,g agent, a 5 buffer, and various additives to control qualities such as stability, film - properties, depos'ltion rates. Typical copper salts include the water soluble salts such as copper sulfate, chloride, nittate and acetate. Other organic and inorganic salts of copper may also be used. Typical of the reducing agents that can be used in alkaline elecl,uleas copper plating baths are ~u~ ",dlddl ,yde o and ru""dl~l."de pl~ulaul:~ such as glyoxal and pald~ulllldll~ de.
B~, ul l~ll i.ies such as sodium or potassium bo, ul "~ e and boranes such as amino boranes are also useful. In acidic copper solutions, h~Ju~llo~lJI! ' such as sodium or potassium hypo~l lo~ ild are used. On the acidic side, acids such as sulfuric may be employed. The pH ddjl,l~ l 11 is used to 15 regulate the plating potential of the bath. A polyamino disuccinic acid is preferably used to chelate the copper. A typical aqueous bath utilizing the polyamino disuccinic acids ad.~dllld~ously contains from 0.002 to 0.60 moles of a water soluble copper salt, the polyamino disuccinic acid at a molar ratio of c~,ul~u~ dlt~ly 1 to 2 times that required to complex the copper, an alkali metal 20 hydroxide in sufficient amounts to give a pH of from 10 to 14, and for exdmple lu,,,,~ I,yde from 0.03 to 1.3 moles per liter. One particularly important need in the ~k:~,l,ul~ss metal plating baths are for chemicals of high purity. This cdn be extremely important since the surfaces being plated must be a,~lu.dl~'ytically active. Many impurities poison the catalytic surface even 25 when present in very small amounts. When this is the case, it is ~mportant that the chelating agents that are used be of high purity. r~ O disuccinic acids that are especially effective and lend ll t~ cv to being easily purified by isolation as the water insoluble acid fomm include ~tl "fl~.le..iid".;. ,d disuccinic acid, dieth~lt,. ,~, idmi. ,e disuccinic acid, and h~ a~id- ";"e disuccinic 30 acid. Ethyla,~elid...;. ,e disuccinic acid ~s a particularly preferred chelant. Used plating solutions, especially copper plating solutions, may be difficult to treat since they contain strong ~ s such as EDTA
(~I,;I~.,edid,~ R~ . acid) that are slowly biode3~adPrl The use of more biode~JIdldlJlt: chelants such as EDDS are particularly useful in this 35 regatd.

-- ~1'0 94/28464 2 1 8 ~ 6 8 2 PCTII~S9410S~.,4 In the pOI~ aliul) of rubber polyamino disurcinic acids are suitably used fûf preparing for example the tedox catalysts used therein. They ddditiùllall~ prevent the ~ iLdliul) of such compounds as iron hydroxide in an alkaline polymerization medium.

In the textile industry, the chelants are suitably used for removing metal traces during the manufacture and dyeing of natural and synthetic fibers, thereby preventing many problems, such as dirt spots and stripes on the textile material, loss of luster, poor wettability, unlevelness and off-shade dyeings.
r~",l,la,yof various other uses are ~ 5 in pl~d.lll~e~ti~AIs, cûsmetics and foodstuffs where metal catalyzed oxidation of olefinic double bonds and hence, dl ~Uidil;CdliUI I of goods is prevented. The chelates are alsouseful as catalysts for organic syntheses (for example air oxidation of paraffins, hydroformylation of olefins to alcohols).
Metal chelates are important in agriculture because they supply micronutrients (trace metals such as iron, zinc""an~di,~se, and copper) which are vital in the Ill~talh~ ..ll of both plants and animals. Plant problems ~o previously ascribed to disease and drought are now ~ d as possible sy."~tu",s of micronutrient d~ l Ibi~s. Today these d~ 5 are generally con~ d to be caused by (1 ) the trend toward higher anâlysis fertilizers cr,..~di,)i,~ fewer~i,,,pu,ili~ ; soils whjch had been A~ t~,~y supplied with trace metals from these impurities' have now become deficient 2s (2) i"l~" " ~ cropping practices which place a severe dem2nd on the soil to SUpply ~ " ul~ul. it~ , to maintain high yields, -~ "ldry addition of trace metals is now necessary (3) high phosphorus rt" lili~dLiùl~, which tends to tie up metals in the soil in 8 fomm Ul ~ dildbl~ to the plant and (4) the leveling of marginal land for cultivation, which often exposes subsoils deficient in 30 micronutrients. The metal chelates of a..,i,~.,d,l,u,.ylates such as EDTA andHEDTA are co"""ol~ly used to chelate micronutrients for agricultural use. The iron, copper, zinc, and ")dr,yd,~ese chelates of the polyamino disuccinic acids such as E~DS can be used to deliYer these metals to the plant. Because of the excellent solubility, these metal chelates are more readily utilized by the 3~ plant than are the inorganic fomms of the metals. This is especially true in highly competitive ionic systems. As a result, the micronutrients that are ~VO 9 ~/2846GI rcT/us941o5-" J
chelated to the pGlya"",~o disuccinic acids are more effic~ent than when compared to the inor~anic sources. The iron chelates of ~rorl", la~ Iydl ~e5e, copper, and zinc with the biUd~Uld idl le polyâmino disuccinic acid EDDS are particularly preferred. BiUd~yld idbl~ chelants would have less residence time in soll.
Further fields of .a" i~ , for polyamino disuccin~c acids ~nclude gas washing, .,u"dit~o"i"g or scrubbing (of for examplQ flue, gec,ll~".,al, sour, synthesls, process, fuel, or h~dlu~,allJul~ ~âS) to remove a~ least one acldic o ~as, p(t~t~ldbl~ the removal of NOX from flue gases, H2S oxidation and metal extraction. Polyvalent metal chelates of polyamino disuccinic aclds are pdl ~;U~ l Iy useful ~n removing H2S from a fiuTd, particularly a gas, containing H2S, by (directly or indirectly) co, l~el ,lil ,9 the fluid with at least one chelate of at least one, preferably one polyvalent metal in a higher valence state such ~hat sulfur ~s formed along wlth the chelate o~ the metal in a lower valence state.
The chelate of any oxidizing polyvalent metal capable of being reduced by reaction with H2S or hydrosulfide and/or sulfide ions and, pl ,~ iJ~y which can be I ~yt,-l~, clt~d by oxidation, ~s suitable. Preferably the chelates are watersoluble. iJ ~IIl,uldl~ metals include lead. mercury, nickel, chromium, cobait, ~o tungsten, tin, vanadium, titanium, tantalum. plat~num, palladium, zirconium, molybdenum, preferably Iron, copper, or IllâllLla~ se, most ~, Jf~.a~ly ~ron.
Polyamino disuccinic acids are sultâbly used In any process of removal of H2S within the skill ~n the art such as those ~, ~",, ~ ~ by United States Patents 4,421,733; 4,614,644; 4,62g,608; 4,683,076; 4,696,8û2; 4,774,071;
4,816,238; and 4,830,838. The polyvalent metal cheiates are read~ly tormed ~n aqueous solution by reaction of an ap~ u~ t, sait, oxide or hydroxlde of the ~ul~ ,. .l metal and the chelating agent in the acld fonm or an alkall metal or . . "" ,u,, 1 sait thereof.
Preferably contact of H2S, I,~ . and/or sulfide with the chelate takes place at a pH of from 6 to 10. The more preferred range is from 6.5 to 9 and the most prefened range of pH is from 7 to 9. In general, operation at the highest portion of the range is preferred In order to operate at a high efficiency of hydrogen sulfide ~bsu,~-t;u,,. Since the hydrogen sulfide ~s an acid gas, there ~s a tendency for the hydrogen sulfide to lower the pH of the aqueous ~ WO 94/28464 pr'TlUS9410:..,4 alkaline solution. Lower pH is preferable in the presence of carbon dioxide to reduce at~sor,uliù,~ thereof. Optimum pH also depends upon stability of a particular polyvalent metal chelate. At the pH values below 6 the efficiency of hydrogen sulfide a~s~,~liu,1 is so low so as to be generally impractical. At pH
5 values greater than 10, for instance with iron as the polyvalent metal, the .ipi~dl;ul~ of insoluble iron hydroxide may occur resultin3 in cl~cu""ousiLiu"
of the iron chelate. Those skilled in the art can ascertain a preferred pH for each operating situation.
Buffering agents optionally useful as cu,,,pù,~ . of aqueous alkaline scrubbing solutions of the invention include those which are capable of ",s~ :.,ing the aqueous alkaline solution at a pH generally in a operating pH
range of 6 to 10. The buffering agents are advantageously water soluble at the Cul)Ct~ ld~;UI I in wnich they are effective. Examples of suitable buffering 5 agents include the dllllll~l ,;u", or alkali metal salts of ~dlLn~lldl~ dl~OI Idt~s, or borates, including sodium carbonate, Li~dl~Ul-dlt~ or sodium borate, particularly Cdl bùndles and biCdl ~Orldl~s when used in the presence of C02 (carbon dioxide).
The temperatures employed in a r,u, ~ ,lil ,g or àbsul ~liol ,-contact zone are not generally critical, except that the reaction is carried out below the melting point of sulfur. In many Cullllllt:n,idl:,, ' " 5, al"o-~.liù.~ at ambient temperatures is desired. In general, temperatures from 10C to 80C are suitable, and temperatures from 20C to 45C are preferred. Contact times 25 cc~ lllly range from 1 second to 27û seconds or longer, with contact times of 2 seconds to 120 seconds being preferred.
Suitable pressure conditions vary widely, clupe~.di- ~9 on the pressure of the gas to be treated. For example, pressures in a cu, Itd~:til ,9 zone may varyfrom one all I ,us,ul ,e, t, up to one hundred fifty or even two hundred all"ùs,.~l,u,~s, with from one dllllù~ to one hundred al",oslJ~,e,t:s preferred.
In H2S removal, preferably at least an amount of chelate in a higher valence state ~lui~;l,;~n,t~l,;., with the H2S to be removed is used. Preferred mole ratios of chelate to H2S are from 1:1 to 15:1, more preferably from 2:1 to ~ /28~ 2 1 80682 ~ s~ s~
~:1 When chelates ~n both higher and lower valence states ~re present, R is generally preferable to maintain a .,o"c~"l, illiul1 of lower valence state chelate at least S times the ~Oll~ llla~iul~ Of tha~ in the higher valence state. When, for instance an iron chelate is used, 'It ~s preferably present in an amount from 1 û0 to 100,000 ppm iron ~n the higher valence state most ~ tnavly from 1000 to 50,000 ppm by welght iron in the higher valence state. The circulation rate of ti1e chelate solution depends upon the hydrogen sulfide level ~n the H2S
CUI llt~;. Iil Iy fluid In general, the circulation rate should be sufficient ~o provide from 1 to 6 moles and preferably 2-4 moles of high valence (e.g. ferric) chelateo for every mole of H2S entering the react~on zone. The contact time of the reactants should be at least 0.05 second or more and preferably ~n the range from 0.02 to 1.0 seconds.
Polyamlno disuccinic ac~ds are preferably used in ~u"li,i"~iù" with additives such as rate ~"l ~àl1~ tor catalysts, for example ~or cv"~.~;u., of H2S to sulfur) andlor stabilizers for the chelates. Cationic polymeric catalystsare advd"la~eou~ and Include pOl~lh~ all l;~ l~s, poly(2-hydroxypropyl-1-N-r"~ "l."u"' ., chloride~ and the 1,1-dimethyl analogue, polylN-(dimeth~la.,.i(,u.,.~ "~l) acrylamide], poly(2 v;"yli., ' '; ~u~
bisulfate), poly(~ llylJi."e~ l allllllulliulll chloride) and poly(N-dimethyl ululu~uyl)~ 'a~ ,I;u~ These cationlc polymers are well known and are cu~ ' "y available under various ll aJ~l lal l .es. See, for example, Cu"""~".~ Oraanlc Fln~ n~c oy J. Vostrcil et al Noyes Data Corp. 1972 .
Other u3eful cat lonlc cataly3t~ are set for~h ~n J. Macromol. Sciance-Chem. A4 pages 1327-1417 (197û) .
Pre~erred cntaLyr~t~ lnclude polyethylene amlnes and poiy (dially1dimethyl ammonium chloride). Preferred Cvl~ l ' al~ul~ ranges for the polymeric catalysts are from û.75 to 5.û welght percent, and from ~.0 to 3.0 weight percent Is the most preferred range. The amount of polymeric catalyst is sufficient to prû~de a we~ght rat~o o~ ~ron or other polyvalent metal In the range frûm 0.2 to 1û:1. Cvllc~llllaliOIls of from 10 to 25 ppm in solution are preferred. S' ' " I~ agents include, for example bisulfite lons such as sodium, potassium, lithium, all""u~, , bisulfite and mixtures thereof. They are used in stabilizing amounts, that is amounts su~ficient to reduce or inhibit rate of d~l adal;vl ~ of the chelate, p,~r-, aL,ly from ~0 ~`1/Z.,4C4 2 1 8 0 6 8 2 I'CIIUS9~10S~"4 0.01 to 0.6 ~:u,uiV ,1~ per liter of solution, more pre~erably from 0.05 to 0.3 equival~"lsl;;t~
After the chelate of lower valence state is produced from that of higher 5 valence state, it ~s preferably oxidized back to the higher valence state and recycled. Oxidation ~s suitably by any means within the ski~l in the art, for example ~16~l~u~ ically, but preferably by contact with an oxygen-co. Ild;. ,i. .g gas, for example air. If CO2 is absorbed, it is preferably removed before contact wdh the oxygen-~,u"t..:. Iil lu gas. The oxygen (in 1~ wnatever foml supplied) ~s dd~ ~. Ita~OUS~y suppl~ed ~n a :,lu~ul ,~u, "~t, i~
equivalent or excess with respect ~o the amount o~ lower valence state metal ~on of ~he chelate or chelates present ~n the m~xture. Preferably, the oxygen issupplied in an amount from 1.2 to 3 fold excess and in a cûl~ dl,uil of from t percent to 100 percent by volume, more preferably from 5 percent to 25 15 percent by volume. Temperatures and pressures are suitably Yaried widely, but generally those used in the cul Itd~,lil 1~ zone~s) are prQferred, preferably temperatures of from 10C to 8ûC more preferable from 20C to 45C w'dh pressures from 0.5 ~111110 ~J1161d to 3 or 4 ~tlllOb~ preferred. Mild oxidizing conditions are generally pre~erred to avoid dey,a.ldtiull of chelating20 agent. Such conditions are within the skill in the art.
Sulfur produced by reaction of H2S with the polyvalent meta~ chelate ~s optionally solll' "' 1, for example by oxldat~on. Ox~dat~on is sudably by any means w~th~n the sk~ n the art. When S02 ~s present or eas~ly gt" ,t" dt~d by zs oxidation of H2S (e.g. using oxygen or elt~ull ù~ dl means) 'd Is a preferredoxidizing agent to produce, for example tl,' '' ' ?~ from the sulfur. Other suitable oxidizing agents ~nclude for example alkal~ metal or dll~lllUll;~ saits of ~norganic oxid~z~ng acids such as perchloric, chloric,' hypochlorous, and fJe" lldl l~dl 1~. afids. Otherwise, the sulfur ~s optionally recovered by means30 within the skill ~n the art including f' ~ ' ' 1, settling, c-~:"t, ir~ S '' " fiitration, flotation .

74û69-198 Processes of the lnventlon of the dlvlslonal appllcatlon lnclude, for lnstance: a process for removlng at least a portlon of H2S from a fluld stream contalnlng H2S
whlch comprlses (A) contactlng sald fluld stream (optlonally ln a ~lrst reactlon zone) wlth an aqueous solutlon at a pH
range sultable for removlng H2S whereln sald 18a .. .. ... .

941284G4 2 1 8 0 6 8 2 I'Cl`IU57410~ 74 solu~ion cu.~\~nl:,es at least one higher valence polyvalent metal chelate of a po1yamino disuccinic acid whereby said h~gher valence polyvalent metal chelate is reduced to a lower valence polyvalenl metal chelate. Optionally the aqueous solution aci iiliun y comprises an oxidizing agent capable of 5 oxidizing elemental sulfur to soluble sulfur compounds, and/or one or more water soluble cation~c polymer~c catalysts and~or a stabilizing amount of a stabilizing agent each as bisulfite ion.
The process optionally includes at least one additional step such as:
o (B) bUI lab'til 1~ sdid solutlon contalning the lower valence puly-;. .I che~ate ~n a second reaction zone wRh an oxy~en-containing gas stream whereby sa7d chelate is It~U~ idi t i, (C~ recirculating said reoxidized solution back to said first reaction zone;
(D) feeding said aqueous solution from said oxidation zone to a sulfur recovery zone;
(E) removing Srom said aqueous solution at least a portion of sa~d sulfur and Il .3(~ ' , (F) ~ ldt~ the aqueous admixture ~n a ~U~ ld~iUl~ zone to produce a ll:yt~ lal~d reâctant;
20 (G) retuming aqueous admixture containing It y~ d reactânt from the ~yt~llelal;ull zone to the bul~a :tillg zone;
(H) ;, Ibil It~l dlil .g hydrogen sulf~de to fomm sul~ur dioxide;
(I) selectively absorbing sald sulfur dioxide ~n an alkaline aqueous solut~on without S.JIJ:.lal,lial carbon dioxide 6i~:7ul~iUII to fomm a solution of sulfites 25 ess~"lially free of inso1uble baliJUllall ~.
(J) c~ said sulfur with sa~d sulfites to fomm soluble sulfur compounds;
(K) l~bin;b~al~ said reoxidized polyvalent metal chelate back to said f1uid all~6 ~u~uus cheiate solution contacting step; and/or (L) cul~ rJtl~",.dl steam in a reaction zone, ~ tiy in said first 30 reaction zone, for r,u. ,làbl;~ ~ said reduced poiyv.,l~. l metai cheiate.
74û69-198 2~ 8Q682 *
Composltions of the lnvention o~ the dlvlYlonal appllcatlon, thus, lnclude aqueous 301utlons of polYValent metal chelates (ln one or more oxldatlon states) wlth at least one of s H2S, sul~lde or bl3ulflde lons, rate enhancers such as poly(dimethyldlallyl ammonlum chlorlde) and/or polyethyleneamlnes, and/or stablllzers such as blsulf lte lons .

l9a 7gO69 -1 98 '~ WO 9~/28464 2 1 8 ~ 6 ~ 2 Pcr/uss~/o . 4 Similarly, polyamino disuccinic acids are used in removal of nitrogen oxides, preferably nitric oxide (NO), from fluids co, lldil lil l9 them. For instance, nitrogen oxides (N0x) and S02 can be removed from flue gas streams by 5 absorbing the SO2 using an absorbent or reactant therefor, particularly an amine based absorbent such as a nitrogen-containing heterocyclic compound preferably having at least one carbonyl group such as a ~i~,e, d~;~ IUI ,e, ~Jipe, kJi"v~-e, piperidine, piperazine or triazine having a carbonyl group;
hydantoin; cyclic urea, ' '~ ,e or morpholinone in conjunction with a chelate of a polyvalent metal. 1 Iu"t,se"tdli./e metal ions are chromium, cobalt, copper, iron, lead, ."al~yd,~dse, mercury, molybdenum, nickel, palladium.
platinum, tin, titanium, tungsten, and vanadium; preferably iron, copper! and/ornickel all ~referably with a valence of +2, the more preferably iron, most preferably iron in the ferrous state. Such chelates are conveniently prepared 5 by admixing a vrdter soluble salt of the metal, such as a sulfate or acetate with a wdter soluble form of the chelating agent. for example a salt, advd, ,ldyeuusly in water. The chelates are useful in any process within the skill in the art such as those disclosed in United States Patents 4,732.744 to Chang et al.;
4,612,175 to Harkness et al.; 4,708,854 to Grinstead; 4,615,780 to Walker;
20 4,126,529 to DeBerry; 4,820,391 to Walker; and 4,g57,716 to Ciul,a,.û..: et al. When an SO2 absorbent is used, it is preferably regenerated, more preferably themmally I ~:9el l~ldldd, and preferably recycled. The Cul IC6`l 11l dl;VI) of NOX in the fluid (directly or indirectly) contacting the chelate is preferably from 1 ppm to 15,000 ppm by volume such as is found, for instance, in flue 25 gases from buming for example coal.
Whether used with an absorbent for S02 or not, the metal chelate is ad~,d,.~a~vu ;l~ present in the solution which contacts the NOX co,~tc.;..;.,g fluid at a metal ion cu- ,.it:, llldliun greater than 100 ppm with a chelatiny- agent to 30 metal ion molecular ratio of greater than or equal to one. The metal chelate is preferably present at a metal ion co"w~ Ill dliUI) of 1,000 to 10,000 ppm and a chelating agent to metal ion molecular ratio between 1:1 and 10:1. The optimum amounts depend on the chelating agent generally with preferred ratios between 1:1 and to 5:1.

~ro 114/~84Ç4 2 ~ 8 0 6 8 2 rCTlUs~4105~ 4 An absorber is suitsbly operated at a Itllll,u~ln~ of from 0 to 120C, but is prelerably opera~ed at a tempera~ure of from 5 to 95C. In the process, both absorber and (optionally) a stripper are typically operated at a pressure of from t~tl~lu:"ul~ , to 10 ~I IlU~ 5 (e.g. 0 to 69 Pa gauge), however, 5 tlll . .o~l ,e.~ pressure is preferred for the convenience of lower equipment and operatin~q costs and reduced SO2 absorbent losses. Higher temperatures and pressures are not v~l it~. ~vus so tong as they are below the ciecv. . IpuSiliv temperature of the chelate and absorbent, ~f present. The absorber is preferably ill.A~.,t~ d at a pH between 3 and 8 to reta~n NOX aL,sv.L,t,.,ce in o t~le absorber.
Chelates absorb NOX or act as :,lvl.:l ,iv, . .~I, i., reactants to Increase ~hesolub~lity of NOX in aqueous solu~ion. f l~f~ ly sulfite and/or bisulfite ions c ~ ~ly referred ~o here~n as ~sul~ites~ are also present. Such lons react ts with ~he NOx-chelate complex ~o form imino~iic~ le saits and free ~he c~lelate for NOX d~:,v.~liun. Examples of suitable soluble sulfite saits includesodium, potassium, lithium, Ill.l.,ll~Si~ lll and/or ~,...,. ,-, .. sulfite and/or b~sulfite. When SO2 Is present, SO2 In aqueous solutlon forms sulfurous acld, and ~he cu..r,~..l.dtiu.. of sulfites In the absorbent is generally suffic~ent for 20 ~ o~ al~ forma~ion without ItS~ I ""~, Il, but sulfites may be added, 7 necessary, to malntain a ~,v~cen ,I, dl;VI1 of a~ least 0.05 ~o 1 g-moles/i absorbent, preferably at least 0.1 g-moles/i. A sulfite salt ~s, thus, preferably present with the chelate.
Al~t,--.dli~/~!y, as described In U.S. Patent 4,957,716, t he che lRt e promot es Atjsc,.~.tiu., of NOx whlch may be converted ~o such cv,..~v~ "vb as HN02 And HNO3 which react with HSO3, If present, ~o form l.J~v~Jl...~ e- 3l 'tt. I -(HON(S03H)2, ~b.~ .,t~,~i HADS) and related compounds, which are 30 preferably suhse ~ ntly converted to soluble ammonium and sulfate ions Avval~a,uJ~u~lyatapHof4.20rless,p~f~rnl~1y4. More~n~f~ Liythe ammonium ~ons are subsequently removed, ~or example by dbsvrp~u " and most pre~erably, the sulfate ions are P~
In remov~ng NOX from a fluid, the polyvalent metal chelate is oxidized from a lower to a hiQher valence s~ate. The lower valence metal chelate ~s 74û69-198 .

preferably replenlshed, for example by replacement of the polyvalent metal lon of the chelate, but more preferably by reductlon of the metal by any means wlthln the sklll ln the art, such as by contact wlth a reduclnq agent, or preferably by electrochemlcal means (at a cathode). The chelate ~8, then, preferably recycled.
When electrorh~m1cA1 regeneratlon 18 used, the solut lon contalnlng the hlgher valence polyvalent metal chelate (whlch solutlon 18 preferably flrst [advantageously thermally) strlpped of ~02) la preferably dlrected to a cathode compartment of an electrochemlcal cell comprlsed of an anode ln an Qnode compartment separated, preferably by a mem-brane, from a cathode ln a cathode compartment. An electrlcal potent lal ls imposed across the Anode and cathode to reduce lnactlve oxldlzed chelates to an actlve state. Preferably, an anlonlc exchange membrane 18 used. Heat stable amlne salts may also be converted to free amlne sorbent ln the cathode compartment and soluble salt anlons diffuse from the cAthode compartment through the anlon exchange ~membrane lnto the anode department. Preferably, ln a further step, regenerated absorbent solutlon form the cathode compartment 18 recycled to the N0x contalning flUld contactlng step. The process more preferably addltlonally comprlses a step of ad~ustlng the pH
of the regenerated recycle absorbent to from 3 to 8.
Composltlons of the lnventlon of the dlvlslonal appllcatlon, thus, lnclude aqueous solutlons of the polyvalent metal polyamlno d1succinlc aclds wlth at least one of N0x, at least one twater soluble) sulflte, or at least one absorbent 2 ~ 80682 for S02. Mlxtures of the chel~tes ln hlgher and lower valence states and m~xtures of the chelQte wlth the chelate-Nox complex are also aspects of the lnstant lnventlon.
Processes of the lnvent lon of the dlvislonal appllcatlon, thus, lnclude a process for removlng at le~st a portlon of N0x, preferably N0, from a fluld containlng N0x, sald fluld preferably also contalnlng S02 and sald fluld preferably belng a gas, but sultably belng ln a form such as a llquld, suspenslon, or rrlml~n~te comprlslng the step of (A) (dlrectly or lndlrectly) cont~ctlng the fluld wlth an aqueous solutlon comprlslng at least one lower valence stQte polyvalent metal chelate of a 22a ~ wo 94128464 2 1 8 0 6 8 2 PCTiUS94ll/Jo74 polyamino disuccinic acid and optionally additionally co, Ilc.i";"g an absorbentfor S2 and/or a sulfite.
The process optionally additionally comprises at least one of the 5 following steps:
(B) themmally stripping sulfur dioxide from an S02-rich d~::.Olbel 1~ solution to obtain an SO2-lean absorbent solution;
(C) directing the absorbent solution to a cathode co",pa, 1,1 ,t" 1l in an 10 elt~llU~ lll;Cdl cell, said cell having an anode in an anode compartment separated (preferably by a membrane) from a cathode in said cathode Culll~.dll,nt:"l, and imposing an electrical potential across said anode and said cathode to reduce oxidized chelates in said cathode compartment to obtain a dl~d absorbent solution;
15 (D) recycling said ~,:g~"tz,dl~d absorbent so1ution to cullldulil~9 step (A);(E) converting heat stable amine saits into free amine dbss, i t:"l in said cathode c~lllpdlllll~lll, (F) s~dldlillg salt anions from said cathode cu".pa,l",~,ll through said anionicexchange",r"~b,dneintosaidanodeculllpdlllll~lll 20 (G) circulating an aqueous electrolyte solution through said anode compartment;
(H) p~, "y refreshing said electrolyte to eliminate byproduct salts in said anode C~ drllll~
(I) adjusting said ~g~,le, dl~d absorbent solution to a pH of from 3 to 8 for a25 recycling step;
(J) (when HADS is formed) mixing at least a portion of Il~llu~;...ll;l~e-li .ulÇulldltHn a reaction zone in an aqueous envi.u"",t",l of pH
of 4.2 or less, thereby converting said hydroxyl~",i"edi~ulfonate to dllll~lUllil~lll ions and sulfate ions in a second aqueous solution;
30 (IC) I,ullld~ g said second aqueous solution v~ith a second ~"""ù"i.l", ion-absorbing sorbent suitable for removing ammonium ions from said second aqueous solution and sepa,dli"g said second sorbent from said second aqueous solution;
(L) eluting said second sorbent and exposing the eluted ammonium ions or 35 ammonia to nitrogen oxides at a temperature sufficient to fomm nitrogen and water ll,e,~r,ulll; and/or 23 ~VO 9 tl28464 2 1 ~ 0 6 8 2 1~CT/tJ594/Os~ ~4 (M) removing said su~a~e ~ons from said second aqueous solution by forming a sulfate salt p~ ld~.
The followin~ examples 3re offered to illustrate but not limfl the lnvent lona .5 E~erCelltaçle8 r rrlt lo~ ~Ind p~rt~ ~re by welsht un1ess stAted o~er~vise. Examples o~ the invention (Ex.) are ~iu, laled numet~cally while ol"pd,ali~c samples (C.S.), which are not examples of the inven~ion are desiy, Idl~cJ dl~ dlx:tiu~
10 EXAMPI F 1: PREPARATION OF i_THYLENFnl/`~AI'~CDlSUCClNlC ACID
FROM ETHYLENEDIAMINE AND MALEIC ACID AND PREPARATION OF
THE FERRIC CHELATE
A sample 120.5 grams oi maleic acid (1.03 mole - Fisher reagent ~rade) was added to a beaker. Deionized wâter (120 ~rams) and 167 grams of 50 percent NaOH (Z.08 mole - Fisher reagent grade) were added and the mixture was slirred until dissolution was observed. The resulting solution was 1I dl l~ i tO a t liter stainless steel autoclave vessel usin~ 40 mL of deionized waler as rinse. A sample, 31.03 grams, of ethyl~ ia.,.;,le (0.51 20 mole - cull ll l l~l l 'Iy available from The Dow Chemical Co.) was slowly added to the stirred (magnetic stirrer) sodium maleate solution over a 10 minute period. Then a cap was placed on the autoclave which was equipped with a tl~""u.v~l: and lilr-""u,.,~l~r cullnt~cl~d to a Therm-O-WatchrU temperature controlier (Cu,.l~.,t", "y ava~lablQ ~rom l~ u,.l~ for Research & Industry (Cn~ "lla"" Pa.)). Heat was supplied by a 30~ x 0.75~ (76.2 cm x1.g cm) sect~on of heating tape wrapped around the autoclave whlch was then ~nsu~ated wHh glass wool. Stirring was achieYed by a Illn~ y dr~ven 1.5' (3.8 cm) TeflonTU pol~1~t, u~ lene coated stirrer bar. Temperature was mdil ~t~ ed at 1 40C fûr 9 ilûurs, after which the m~xture WâS allûwed tû cûol tû
30 room tt~ . The carbon NMR and proton NMR o~ the reaction m~xture indicated ess~ lly no remaining eth~ e.lia...il ,e and a very small amount of residual maleic acid. The reaction mixture was adjusted to a pH of au~uluA;l l ldl~ly 2.0 with 36-37 percent hyd. u~i ,lu, ~ acid (. c,. . "- ,~l u~.lly available from Aldrich Chemical Co.). A powdery whHe ~ i,uildle developed and was 35 filtered with Whatman #41 filter paper in a Buchner funnel. The plt~ ilall:sdsoiid was washed twice with 300 mL of deionized water. The resultinrJ so1ids 74û69-1 98 1~ WO 94/28464 2 1 8 0 6 8 2 PCrlUS9410__,4 were dried ovemight in a vacuum over at 60C. Ap,u~u~J~dlel~ 108 grams of product were obtained ~74 percent yield of acid). The carborl NMR and proton NMR indicated ess~ lly pure ethylenediaminedisuccinic acid.

STABILITY AT VARIOUS pH s An d~uulu~ ldlt~ly 0.01 M iron (ferric) - ethylenedid",i"eJia,Jccinic acid chelate solution was prepared by adding 1.63 grams of eth~ "edid, n;. ,ed;~.sccinic acid and 200 mL of deionized water to a beaker.
The slurry was stirred with a magnetic stirrer bar and the pH was adjusted to 10.0 with 1.43 grams of 50 percent NaOH solution. A sample 2.4 grams of iron nltrate solution (11.75 percent iron) c~",r"t~,.;ially available from Shepherd Chemical Company were added with stirring The pH of the solution which drops to 1.7 was adjusted to 6.6 with aqueous ammonia (29 percent cùn~ t "I,dliùn) solution ~cu"""e,ui~ll" available from J. T. Baker Chemical Co.).
The iron chelate solution was then diluted in a volumetric flask to a final volume of 500 mL. Fifty gram aliquots of the solution were then placed in four 2 oz (û.059 I) bottles and the pH of each was adjusted to 7.0 8.05 9.1 and 10.0 20 , t~ u';~ly with a few drops of an aqueous ammonia solution. One 5û gram aliquot was adjusted to a pH of 6.0 with a few drops of dilute h~dlu~ lol i~ acid.
and one 50 gram aliquot was adjusted to a pH of 10.5 with a 10 percent solution of sodium carbonate (8.5 9). The sample that was pH 10.5 develops an iron hydroxide ~ dl~: almost i,n",edidlely. The sample at pH 10.0 25 begins to form iron hydroxide after 4 hours. The samples that were pH 6.0 7.0 8.05, and 9.1 do not develop any noticeable iron hydroxide. The samples were allowed to stand for 6 days at which time the ~overheads~ (that is liquids not cul ",~g visible solids) from each of the samples were analyzed for soluble iron by inductively coupled plasma ~ usc~,y. Results are given in 30 Table 1.

2~ 8~682 1~ r~'O 94/28~64 PCT/US9S10.
Table 1 Fe(lll~ - EDD'' vs pH
pH ppm^ Fe in solution percent Fe in solution 6.0 669 100 7.0 671 100 8.05 671 100

9.1 674 100

10.0 235 35 10.5 74 10 t parts per million by weight 5 This data shows that EDDS can complex iron and keep it in a soluble fomm (and thus availa~le for reaction) at the pH values that are used for the I '' '' ~s described in the invention (that is ~ UIUyld,UlliC bleaching agents hydrogen sulfide abatement and other processes.) FXAMPLF 2: PREPARATION OF DIETHYLENETRIAMINE N N~-DISUCCINIC
ACID AND STABILITY AT VARIOUS pH's Diethyl~n~:~, idll~il ,e disuccinic acid was prepared and isolated by the procedure of Example 1 except that 51.5 9 of diethylenetriamine were used in place of ethyl~,~e-lid",;"e and 116.1 9 of maleic acid were used. Also, 160.0 9 of 50 percent sodium hydroxide solution were used. The ability to complex iron at various pH values was d~lt"",i,~ed in th0 same manner as was described for EDDS in Example 1 with the results in Table 2.

j~ ~0 91/28464 2 1 8 0 6 8 2 Pcr~sg-~los pH ppm^ Fe in percent Fe in solution solution 5.9 531 99 7.0 526 98 8.0 535 1 00 9.2 527 99 10.0 531 99 10.5 166 31 1 1.0 22 4 ~parts per million by weight 5 This data shows diethyl~"t~llid",ille N N"-disuccinic acid is an excellent chelating agent for iron and enables iron to remain soluble and available for reaction for the uses described in the invention.
FXAMPLF 3- BiODEGRADABlLlTY SCREENING VIA ASTM D2667 10 SEMI-CONTINUOUS ACTiVATED SLUDGE TEST
The procedure of ASTM D-2667-82 was used to determine the inherent biode~ulddduiliIy of EDDS.
Copper titration value was used to measure the extent of biodegradation of the chelating agents during the procedure. rtration was performed using ammonium purpurate (indicatorforcu,,lplt,,~u,,,el,i~.titration ~u,l""e,. ;ally available from Aldrich Chemical Co. j Inc. under the trade de~ , Id~iUI) Murexide) as the indicator at ~u~-lu~;,ll~t~ly pH 8 and using sodium acetate as 20 buffer. Titration of EDDS in 1û0 mL water with 0.01 molar copper chloride resuited in a 1:1 (molar) chelation of copper. Analyses were pe~u""~d daily for a period of 28 days.
Using the above procedure, EDDS was found to be greater than 80 25 percent L,iudeu,,dddble in less than 28 days.
n 1-- ~o 94/28464 PCT/U594//~_ .4 A control was used to verify the absence of interfering chelating substances in the test.
These resu.ts of the bio~idy~ 'ity test show that EDDS was 5 inherently biodegradable and could be expected to be utiiized by ~, ydl~;;.lllS in a municipal treatment facility after an ~ c~ acclimation period.
FXAMPI F 4: AND COMPARATIVE SAMP- ES A: REDOX POTENTIALS FOR
EDDS AND EDTA

The Reduction Potential of ferric ~ s were measured using nommal pulse pulaliJyldyl ,y with a saturated calomel reference electrode.
rolali~ld/ul~i~; data was obtained on a Bioanalytical Systems BAS-100a Vollal"",~l~k, Ar.alyzer interfaced to a Metrohm VA 663 Multimode electrode stand according to the procedure described in Electrochemical Methods, Fundamentals and A,, ' " ~s by A. J. Bard and L F. Faulkner, 1980, Wiley.
Solutions were prepared of c~o~ 5 of EDDS (Ex. ~) and EDTA
(ethylt!l)e. id" ~ aacetic acid) (as C.S. A), 0.001 molar in conc.-,-, .l.dlio,~ in iron (Ill) [added as ferric p~ l.,l.lo,dl.~ and with a 10 mole percent excess of20 chelating agent. The solutions were 0.1 molar in NaCI04, and adjusted to pH
5 w.th NaOH and/or HCI04 as needed to reach the stated pH, diluted with the same electrolyte solution. ~ al~ electrolyte was used because p~,.,l,l.~,dl-~was'non-coo,di,,d~i,,y~thatwasitcannotinteractwiththeferric center and interfere in the -~p-~l i" ,~"I.

Table 3 examplel chelate reduction sample potential Ex. 4 Fe(EDDS) -126 mV
C.S. A- FetEDTA) -135 mV
not an example of the invention 30 The polarographic data shows that Fe(EDDS) gives a very good reversible reduction. The Fe(EDDS) was 10 millivolts easier to reduce than the C~lllllli3~idl1y used Fe(EDTA). This indicates that the Fe(EDDS) complex will WO 94128464 PCT/U59411)_ _ ~ 4 oxidize silver in the ~l lUlUy~d~JI ,i~ bleach process bud was not sufficientiy strong as an oxidizing agent to inRiate bleach-fixer stabil'dy problems.
The data in Table 3 for EDDS represents an average of two slightly 5 different potentials distinguishable at high resolution. Thus, there appeared to be two solution species in the Fe(EDDS) which were close in potential. These are believed to represent different isomers of the complex since ethylt,ne.l;d",;"~.lisuccinic acid has two asymmetric carbons as discussed earlier. The different isomers of the puly...~ lo disuccinic acids and their metal 10 cù".~ es are wRhin the scope of the invention.
FXAI~PI F 5: H2S ABATEMENT
A 2000 mL sample of 2 percent Fe (Ill) solution prepared from 15 ethylenediamine disuccinic acid and iron nRrate (pH adjusted to-? wRh aqueous ammonia~ was placed in a four l'lter kettle equipped w'dh a stirrer, themmometer, heating mantle, temperature controller, gas lines, caustic scrubber lines, pump, and sulfur filter, and allowed to equilibrate. The t~mrePtllre was maintained at 120C. A gas mon'dor was engaged and lead 20 acetate tape placed around the flask joints and gas fittings. Air at d~JlU~illldl~ly 500 standard cubic feet per minute (scfm) t14,160 I'ders per minute) was sparged into the bottom of the flask through a 7~u stainless steel fr'lt using 1/4 (0.64 cm.) stainless steel tubing. Air sparging was done for 30 minutes to assure there was little fenous iron present. After the sparging was ~5 cu""ul~te:r~, 100 scfm (2832 Iders per minute) of a mixture of H2S and N2 gases were introduced for 10 minudes to the reaction mixture through the 7,u sparge frit. After the adddion of gas mixture, some sulfur particles were noted fomming on the surface of the reaction mixture. No breakthrough of the H2S
gas was dt~ttl" l li, l~d at the 10 ppm level by the monitor and no darkening of30 the lead acetate paper was observed. The gas was shut off and the sulfur filtered from the soludion.
This data shows that the ferric chelate of ethylenediamine disuccinic acid is effective in the a~dl~",~"l of hydrogen sulfide.

-vo s~ns464 2 1 8 0 6 8 2 Pcr/uss~lo ~ .
EXAMPLF ~: CHELATION OF COPPER WITH POLYAMINO DISUCCINIC
ACIDS
Ethyienediamine disuccinic acid and diethylenetriamine disuccinic acid 5 were titrated with standard 0.01 M copper chloride solution. The titrations were p~, rull ~ ,ed using ammonium purpurate (indicator for cu" ~ple.~u"~etric titration collllll~l~,idlly available from Aldrich Chemical Co., Inc. underthe trade desi~ dliu" Murexide) at a pH of ~uy~o,~ dlely 8 using sodium acetate as buffer. Both polyamino disuccinic acids c~lllpl~ d copper at a molar ratio of 1 mole of copper per mole of polyamino dlsuccinic acid.
EXAMPLE 7: COMPLEXATION OF COPPER IN ALKALINE SOLUTIONS
To be effective in an ~l~ul, ules~ copper plating bath, a chelating agent must maintain the copper in a soluble form in the pH range of 10 to 14. An especially preferred range is 11 to 12.~. To determine the effectiveness of the polyamino disuccinic acids to prevent the u,t~Ci,uildliul, of copper across this pH
range, a 0.05 M copper chelate solution of ethyl~"e~;lia,~ ,i"e disuccinic acid was prepared from copper chloride, ethylt" ,e~id",i,~e disuccinic acid and sodium 20 hydroxide. Ap~lu~illldl~ly 70.0 gram portions were adjusted with sodium hydroxide solution to pH values of 10, 12, and 14. The ~I,~ edid,l,i"e disuccinic acid was observed to maintain the copper in solution at these pH
values p", ./~ il ,g the ~ ui~Jildliull of insoluble copper hydroxide. By ..~""Jdn:,on, a 0.0~ M copper solution prepared without the polyamino 25 disuccinic acid ligand, used in the same manner at a pH of 10 ,12 and 14 resulted in ,ul~ui,uildliul~ of insoluble copper hydroxide from the solutions almost i" ", le~lidl~
FXAMPLF.~ 8 AND 9: DISSOLUTION OF IRON OXIDE SCALE
A sample, 1.0 gram, of ethylen~did",i"e disuccinic acid (EDDS) was dissolved in deionized water, and sufficient aqueous ammonia solution was added to obtain a pH of 9Ø Deionized water was added to obtain a 5 weight percent EDDS solution. The resulting solution was heated at 1 00C for three 35 hours with 0.2 grams of iron oxide (Fe3O4) and cooled to room temperature.
The amount of soluble iron was then determined by inductively coupled plasma ~ wo 94/~8~ 2 1 8 0 6 8 2 PCTIIJS94/0 4 S,Ut~ US~U~Jy. After 3 hours, a~ UA;llld~ y 31 weight percent of the iron oxide was dissolved. (Example 8) - In a similar ~A~,e,i",~"~ an EDDS solution was adjusted to a pH of 4.5 5 with an aqueous ammonia solution. Afterthree hours at reflux, a~ UAillldl~ly 7û weight percent of the iron oxide had dissolved. (Example 9) This data shows that d"ll"ul,idl~d polyamino disuccinic acids are effective in dissolving iron oxide scales.
EXAMPI F 10: PREPARATION OF ZINC CHELATE
The zinc chelate of ethyl~"edid",i,)e disuccinic acid was prepared by dissolving 0.0055 moles (1.64 9) of ethylenediamine disuccinic acid in 6.û
grams of deionized water and 3.2 grams of 25 percent NaOH (sodium hydroxide). A sample, 0.005 moles (0.68 g), of zinc chlofide was added with stirring. The final pH was adjusted with 25 percent aqueous NaOH solution to a pH of 7.6 and deionized water was added to obtain a final solution c~, lldil lil)9 2.8 percent chelated zinc.
FXAMPLF 11: PREPARATION OF MANGANESE CHELATE
The ",anyd,)ese chelate of ethylt~"edid",i"e disuccinic acid was prepared by dissolving 0.0055 moles of ethyl~ id,oi,le disuccinic acid in 5.8 25 grams of deionized water and 2.6 grams of 25 percent NaOH solution. A
sample, 0.005 moles, of MnCI2-4H2O (1.0 9) was added with stirring. The pH
was adjusted to 6.7 with 25 percent NaOH solution, and water was added to giYe a final solution containing 2.4 percent chelated ",a",u,d.)ese.
.

Claims (14)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of electroless deposition of copper upon a non-metallic surface receptive to the deposited copper characterized in that the non-metallic surface is contacted with an aqueous solution comprising a soluble copper salt and a polyamino disuccinic acid.

2. The method of claim 1 wherein the solution has a pH of from 10 to 14 and additionally comprises a reducing agent .

3. In a process for plating copper on non-metallic surfaces, only selected portions of which have been pre-treated for the reception of electroless copper, by immersing the surface in an autocatalytic alkaline aqueous solution comprising, in proportions capable of effecting electroless deposition of copper, a water soluble copper salt, a complexing agent for cupric ion, and a reducing agent for cupric ion, the improvement comprising using as the complexing agent for cupric ion, a polyamino disuccinic acid.

4. A bath for the electroless plating of copper characterized in that a complexing agent for cupric ions is a polyamino disuccinic acid.

32 A method for removlng iron oxide deposits from a surface characterized in that the deposits are contacted with a solution comprising an ammoniated polyamino disuccinic acid.

6. A method for removing H2S from a fluid by contacting said fluid with an aqueous solution at a pH suitable for removing H2S characterized in that said solution contains at least one higher valence polyvalent metal chelate of a poly-amino disuccinic acid.

7. The process of claim 6 wherein in the chelate the metal is Fe+3 and the polyamino disuccinic acid is EDDS.

8. A method of removing NOx from a fluid characterized in that the fluid is contacted with an aqueous solution of at least one lower valence state polyvalent metal chelate of a polyamino disuccinic acid.

9. A process for producing an iron complex of a poly-amino disuccinic acid comprising reacting a polyamine disuccinic acid (i) with ammonia or an alkali metal hydroxide selected from sodium, potassium or lithium, and (ii) an iron salt or iron oxide in an aqueous medium to give a corresponding polyamino disuccinic acid iron ammonium or alkali metal salt.

10. The process of claim 9 wherein the polyamino disuccinic acid is reacted with ammonia and iron oxide.

11. The process of claim 10 wherein the iron oxide is Fe3O3.

12. The process of claim 9 wherein the polyamino disuccinic acid has at least two nitrogen atoms to each of which is attached a succinic acid or salt thereof wherein the polyamino disuccinic acid has from 10 to 50 carbon atoms which are unsubstituted or inertly substituted and from 2 to 6 nitrogen atoms, said nitrogen atoms being separated by alkylene groups of from 2 to 12 carbon atoms each.

13. The process of claim 12 wherein the polyamino disuccinic acid is ethylenediamine-N,N'-disuccinic acid.

14. The process of claim 13 wherein the ethylene-diamine-N,N'-disuccinic acid is the (S,S) isomer.