CA2052461A1

CA2052461A1 - Guard membranes for use in electrodialysis cells

Info

Publication number: CA2052461A1
Application number: CA002052461A
Authority: CA
Inventors: Frederick P. Chlanda
Original assignee: Individual
Current assignee: Marmon Industrial Water LLC
Priority date: 1990-09-28
Filing date: 1991-09-30
Publication date: 1992-03-29
Also published as: EP0553136A1; WO1992005863A1; AU8656091A; US5288378A

Abstract

ABSTRACT The present invention relates to an improved apparatus of the type containing membranes which are selectively permeable to ion transport and a related method. The apparatus comprises at least one guard membrane located adjacent to a first membrane. For weak acid systems a conductive bridge is formed between the guard and first membrane, either by adding an adhesive layer between the membranes or by treating the surface of the guard membrane. The adhesive layer between the guard and first membranes is preferably highly water swollen. The apparatus comprises at least one unit cell comprising at least one guard membrane which is adjacent to and in contact with a first membrane.

Description

5cF-30~ i2~ ~01`1 ~LLiET`; 51GNRL L f~W Otl~ i . IU '~lbl~ SX;bY
~ `` 2 0 ~

.~.9 r~ 07 ~ ~SO~
~hls inv~ntion r~l~ee~ to an ~pss el~c~ro~laly~i9 app;~3tu~ an~ ~od. IIDr~
part:lcul~rly, the ir~ven~lon 1~ a ~ppara~ antl o~ll for u~ ~n such ~n z~pparatu~ ri~ing a~ l~a~t on~
guard me~ran~ locatQd adja~ent to a ~ir~3t ~3~rane a~
barr~r.
~o ~e~gL~
~ctro~liaiyri~ u~ dir~ce currone aa ~ to c~.u5~ v~ont o~ lon~ oluticnc.
151e~tr~dlaly~i~ proc~ Qo ~r- well kn~wn in ~h~ art anl are ~ ic~ carried tmt in a s~cJc ~rrang~l~nt ~5 cc~pri~inS~ lural~ty ol~ ~lat ~h~et ra~bran~ Tho ~t~ak cofl~l~e~ cf ~l~ctro~a~ (~de ~nd cathcd~) ~t ~le~O~e end ~nd a ~r~.~s ~2 ~abr~ne~ a~ qJ~k~ec ar~ ope~ in ~Q ~1~11~ to ror~ a ~UltipltC~y o~
comp~ nt~ aratod by th- ~ran~Y. q'h4 D~ori~y

2 D ef th~ ~taclc b~ween th~ lQct~d~ co~pA~nt~
co~pr~eJ~ a rep~atlng ~erl~ of Imit~ of d~rfer~e ~s~br~noo ~t~ ~olutlon co~rt~n~ b~oon nQ~ghbor~ng ~br~eo. rh r~poatlng ~ni'c ~ c~llQd tha ~nit ooll, or ~lnply, a call. ~no ctaclco a n lr,c~ or~ tl~an ono ~ o~ t c ll. 9t~ ~y bo ~d ~r~:D an stilck to ~noth-r ln order to OptiJliZ-p~COC8-- e~rlc~oncy. U~ually tho ch~ng irl coz~o~ltlon o~ a etr~ a~r one pac~ h the Jt~
~o~t~ol~ 11 ~t the olut1ono ean l~o t~r~:lul ~r

3~ ~in~ pw~p~ to ~n~ rro~ r Qyo~o ~. A~ltlon or h ~01~t~o~ eo ~nd ~ 1 or prol~uc~ ~ro~
~q¢y~ ,oo~ a~n t4 oad ol~;h c:w~tlnu~ or p-rlodlc~lly in ord~r ~o control ~ho conc-~ntration Or prod~cts ln a d~sired ~l~nge.
Tre~tnont o~ a~u~ ~olt ~o by oleaC~od1~ly~ o for~ ~oid ~ a frs~ Ul- ~lt ~C Ic:no~ OU9 r~lt ~tr~ ~ to an ~E~ 91 ~ 3' r~Jrl i~LL~ ~NHL ~ 'J L't~ l . !U Ylbl.;~ ~C~ r~
~2~

i9t~0c~1alyti.c water spl~tin~ app~r~tU:~ ~hich ~o~prL~s an 014~t~ 1ye~ ~tack and a ~ ~r ~lect~odialytic~lly gplitt~ng wator. A u6~rul app~r~tU~ isclo~ l in U.S. l?atent N~. 4,740,2gl.
S u~cfu2~ ~e~nJ to ~yl~t ~4ter 'co ~) and ~ a b~ol~r ~ rane Su~h a~ dl~clo~-d in U.S. P~ nt No.

4,766,i61. Ih~ bi~ ~e i~ zoapri~od o~ 4nion ~electiv~ ~nd c~tlon 40~0ct~v~ l~y4r~ o~ ion excnanqo ~ater ~ al . ~zl or~ r tha ~r~ to ~ lon i~ a 10 wat~2r 6plitter, t;he layer~ Ulst bo arr~ng~d ~;o that th~
anion l~y-r Gf ~ach Dle~br~n~ i~ clo~er t~ the Anode th~n tho ~nti~n l~y~r. A ~$r-ct current ~ ed through th~ ~eobr~n~ in thi~ con~igur~t~on ulll c~u~ r 8pl~ g Wl~ nydroxyl ion~ bein~ produc~d lS 2nodo ~ldq ~ a ¢orr~pondlng nu~ber of hydrogen ion~
bolng produced on th- c~,tb~odc ~idn o~ th~ ibr~no.
ctrn~lytic ~t~tr-splittlng in ~ t~o-conrp2lrtm~0t Chll h~ n di~clO--~a, ~c~ HX~
~J. 9. P~t~r~t No. ~,39t,680 r~l~tln7 to t~ g~n~trat~on 20 o~ ~t~Dngly ~aldiSl~d oodi~ ~lor~ ooU-~U~ nyC~roXl~o rro~ a~3ueo~ ~o~un ch~O~i~a. ~. S.
~'cont No. ~,60~,14~ ~2~clw-o ~ ~ult~-cha~r t~o-co~p~t~nt ~l~ rool~ c ~t-~ aplitt~ nd ~ m-thod ~ u~inq th~ r~o ~o~ ion a~ n~ olu~l~
25 ~alt~. U~ S. P~t~nt No. ~,S36,269 ~ ô~ a ~ulti-eh~bor t~ ort~nt ~ ctrodl~ t-r ~ ter etho~ ~or u~ing t~ or ~-Cldlrlc~ls~l o2 a~ ou~ colu~le ~J.t~, l~o~ ~ patCnto revl~ e us- o~ t~a-oyr~-nt nl~ a w~t--r pllt~
10 to tr~at ~lta.
co~ort~nt al#;trodlol~tLc ~c~ lit~
~r~ dl~wlos~ld to be co~prl-cd o~ ~lt~rn~ng blpol~r, ~n~on ~nd oa~c~on ox~ ngo w~ana~ ~or-b~r Sox~
~ltornat~n~ aa~, ~lt nd b~- co~p~ nts. U. 5.
3~ P~t~lnt No. ~"7~.0,Z~1 di-cl~ r~:av~y of aci ~EP-~ ,5n~6 F~ liLLiE~ SlG~hL ' HW rlEPT. TO ql!~l3~63586~

, .
3 ~ ~ ~

fro~ ~ateriala co~pri3ing ~cid and salt u~inç~ o,n sl~ctro~i~ly~ ppar~ ua ea co~centrat~ t~e a~i~
~ol lowod by tba u~ ~f ~n el~cro~$a~ $o ~r~e-~:Dmpart~eTIt ~t~r ;pl1t~er to ~eparate the ~cla from .~ th~b ~Al~.
Th~ dos~gn o~ ~emb~ne~ for eloctrod;alysi~
prDca~aE~ ia co~pllC~t~d ~y tho con~licting n~ed~ of obt;~ining low olQc~ al ~e~i~tanco, ~gh p~ c4ivity ~rul go-~d, D~c~nic~ rope~ti~s~, a hlgll 10 ~ nc~ntratiDn a~ rged group~ iH n~&e~l#ry to ~c:h;eve good pe~aelffcti~it~r ~penD~ation ~el~ct;i~ity to eith~r anions or c~tionr~) ~md consid~ra~le ~at~r s~elling i~
need~d to obt~n a lo~.r r~is~nc~ or~or to ain qood ~el~ rity, ~llinq ~ o~nt~o~lQd.
~sis oan ~o ac¢o~plLone~ ~y croasl~nXing tn~ ~ran~
re~n or incorp~rati.ng an in-rt ~atrl~. 1~rly all c~l Hrc~ally avhil~bla ~on exch~ branff- u~ie o ~parat~ r~lnrarc~ br~c to ~upport ~whoAlc~llly e~ on ex¢h~ng~ ~erial. ~n~0~04t ~br~noo ~ra ~0 ~nu~a~l~red by ~hl Gl;~s~ Co. (TOXyO, Jap~n) a~d lo~cuy~a soda Co. L~. ~TOJcUy~ ~:~ty, ~ r ~r~o n~ 5~1~10n ~n~ 21 ov-p~a~. ~e~q ~
Appare~tl~ pr~p~r~ by et~ pa-te ~thod ac d~cr~'~d by Y. ~ tanl, Il. Ya~ne, AM~ ura, a~.
2S 9~..~D-~ ~, 6~9 [196S~. a '~rlts r~orclng ~at~ an ~nt~l ~r1; o~ prw~. Oth~r wid~ v~la~ ~r~ oh a- tbo~e or ~onlc~
Ino. ~9atorto~, ~a) and ~ one ~W11elng~on, Dl~
o~ploy ~ ~absle rolnrorc~nt t~ ro good ~o ~ d~anic~l prop-rtl~. N~tlon ~ n~ ma~ by ~uPont ara ~v-liloble ~rith and ~ithout ~-brlc r~inforce~n~. ~he uJe o~ ~ f~ric ~oin~oreing ~tor~l can improwl tho bu~e: ~ron~:h o~ ~ :~rar~e An~ Yp~C~ y ~psov~ lt9 t--r r~ n~. HD~ r~
~ thu u~ ot th~l r~in~orclng ~t~rl41 can c~u~ pr~ J~:

SE~-30-1991 le:e6 -;~01`1 ~LLIE~ ~IGN~IL ~ J ~E~-. TO 91c13'63~8~9 P.E5 - 2 ~ ~ii 2 ~

~) r~ushn~ axe~æ ~ealln~ ~.trrlcul~; 2) part ~f tbe arf~a i~ blc~c)~d a~r by the ih~r~ d~ i6 not availabl~
fo~ tr~n~portl 3) cr~eklns~ c~n 4ccur ~llon~ f~b*r3; ~) p~cipita~eo c~n ~o~ ins~ide t~a ~b~an~ i~ecau~e oS

5 the not~rog~r,o~ty c~ue~ ~y ehe f~bor~.
~hc~r~ors it i~ d~1r~ t to u~Q ~rarlg~ which do not r~l~ on ~ ~4b~ic rnLn~orc~c0t ts~ achLe~ gobd ~chanic~1 p~o~erties. ~ e~ru#l~ ~4n b~ p~oduccd ~y r~iat~on grafting onto a ~o-~r f~l~ wi~h th~ ~a5 ~0 ~ila ae~rin~ to ~pro~,rs ~ an~a~l proporti~s.
su~ ane~ are pro~u~:od co~or~l~lly und r 'c~-trado na~o Ralpore~ by ~aI ~r~h corpor~tlon, H~uE~p~ugo~ NY. Oth~r m~or~n~ c-n 'D~ prup~r~d bir ~1Y~nt ca~ting a ~olyol~cerolyt~ t~ix ~
15 d~ocri~ in V. ~. P~t~nt No. ~.,0~,32~ or ~ aaselng aolutlon~ o~ i~n aonta~ning poly~r~ ~t~U~ Huf~lcient c~ n~lty to ba ~a~ ~Yollen but wlt~ enouqh w~ in~olula ~t~ri~l to r~ei~t ~olllng. Thl~ typ~
o~ ~no ~at~on Do~r~o ~ ~ a ln U. S. P~tent ~o.
20 ~,73e,7s~ r anlon and blpol~r :~bra~l~a arn d~1~crib~ 0. g. P~t~t Na. ~ 16,5~g ~n~ U. 9. ~J,t~
No. 4,~66,151.
nd op~ation oY clo~trodia;~gaSo ~t~cX~
1~ v 11 Itn~n ~ ~na are ~ 1~ d, rc~r ~
25 by d. ~ ctrodl~ in ~5~ P. ~ y, 1~ on~d-lo, M. N.
d~Plnho ~dlt4r~, t~. ~d~l ~ubl~ahln~ Co., D~ ~t, l~o~l~n~. Car~ful d~-lgn o~ odl~y-la ~t c~c 3~ h~ Dnd opo~tlon to ulnl~- prs~o~uro ~r~r~m~alo ~nO. ~ an ~lp ro~u~ t~ Sallur~
rat- ~n ~ no~ h ~- not m~ lly z~bu~t.
~ nbr~n-u Yhlct~ 3r~ no~ a r~ orc-d g~nor~lly ~t.ll not t~ll in u~, ~h~uld A ~e~br~n~ rail, 3S it u~ually ro~l~ ln a larq~ t-u~ or no~ u-~ Or aE?~ 91 15:~7 Fi~ hLLlE~ Slul~ L ilW DEPT. TO ~16l35a39&'6q P.~6 -~-`` 2~2~

th~ p4~r t~ar r~ t~nc~ o~ m~bran~3 whloh do nc~t Lncludc 4 Yelnfarc~nt. The re~sult~ hole causes ~
le~kage ol! ~oluti~n ~etw~en ~d~cerlt co~p~t~nt~ and u3ually oausee ~ loas o~ curren~ e~lci¢n~y, p3~d~0 c~nc~n~ratLon, Jn~or purLty. Tn~ problsn LB
~sF~clally ~cute w~ allng wlth ~ Dnc~ntr~teO.
slolutians; usu~tly ~ound ~n ~l~ctrodlalytic wat~r ~pl~tS~n~ proce~ t~ d~ocr~bed in U. S.
P~1;en~ No. ~,740,231) IJ. 9. P~tont No. ~,50~,3~3 And ~.
10 g. P~sn~c NO. 4,557,815. Tl~c ~lxin~ of a~id uld Daos c~used ~y ~a~lur~ Of a bipol~ ane ~ n ~
~lact~o~l~,ly~c~c ~t~s splLtting stacl~ c~n r~ tly r~uc:R pr~c~$J ~rr1ci~r~cy. ~ r~n on~ bipolar n~rAn~ ~n ~ tac1c o~ 100 r~ps, lt ~ u~u~lly nacec~ory 'tG dlJaa~ ck ~nd r~la~:~ th~
brc~en ~e~br~n~. ~rcn tl~ugh th~ cwt oS ~ch~ ane D;~y n~t b~ o~m, it ~ blghly d8atra~l~ to awid 3n~ n~ ~own ~o pl~nt to p~ h~s ~ e eon~Llng proc~-. ~ lnrc~rcd blpol~r ~ran~ wld be zO Iwlp~ul, but thH productlon o~ ~rarl~ whish r~t-$n th~ ot:b~r d~slrabl- ~roperti~ ha- proron di~cult. ln ;pro~urs ~ n ~ren ~rooe~eo~
1- ~11 knolm to u~ ~ ~oroUJ ~uort to onh~n~ U~e sloc~aniaal ~or~no- ot othvloo woak ~br~no~.
2S 8~ t~uc~tu~ n~Y g~noz~lly noc ~n u ~ ln ~l~tro~ Lyo~c, pro~l~ly ~auc- o~ probl~- ~lth concl~n1 isn pola;~i2~tlw- and d~ natlon c~u-ad by dl~ nc~ ln Y~lt~ n~ort ~t~n tha layor~.
~t 1O ~a~1~4b~- to ~,ul~i~ oi~ o~ ~o~n ~0 ~ branoo on ~roo~e e~ 1enoy a~ lncr~o tn-int-rYal ~otw~n p~nt ~ do~u cau~ uch 14aXago. It 1~ o d~ b~- to provi~ a lly~ts~n o~abl~ ~t lmpr~rir~ tllr ~ ctrlcal ~r~on~nco of bipol~r wr~bran~
~urthor, it t~ ~eon ~o~nd ~ot in -_P-30-Lq~l .5:0I rP01`1 ~LL!E~) Sl-~NI~L I ~IJ 3EFI. ~0 ~1161_5639~

2~32~ ~

~lectrc~dl.alysls o~ w~ak acid ~y~ite~Y guard :&e~ne~
~h~ch ~re ad~a~nt: to tl~ ~irsct 3D~Dbran~ "~ep~r2~t~"
~om~ nco~ ~h~s re~;ulto from ~or~ti~n o~ ~ non-~ondu~ ng l~y~r o~ k ~oid or ~
5 :~ub~lG ~etw~ suard and tnc f i~:ct ~r~n~ e non-c~nductin~ lay~r ~reat~ incr~a~ tbn~ Elot~rltla~
~rop ~crc~ tl1~ cell to exc~;~iY~ly lligh l~ . For guord ~ n-c to bo ~r~ct'cQl ln Y~k ~c$d ~to~4 i'e t~ ~soç4ssAry to Sind q~d ~Pb~ane~ w~ioh will n~t 1~ oeparAtc rro~ ~hc r~r~ ipol~ brane ~u:inq u~e.

The preson~ invent1on relat~ ~o ~n i-pro~
~p~re,tu~ o~ th~ tyy c~ ain~ng ~e~bran~ ~h~ re lS c~ ti~ly per~bl~ ~o lon tr~ h~ re~en~
ln~entlon lnc~ D an ~pp~ nd ce~l ~or uoo in O~JC~ ~pp~r~t~, VhlOh oO~lG~ at loact ~n~ gu~d r~bran~ l~cat~ ~d~ac~nt ~co ~ 21r~t ~r~ne to prolr~d~ qe b~i~ Hhould the rlr~t m-mbr~na 20 lQ~k or ~Ha3t. 'rt~ gu~rd _~an~ o pro~
prat~ct~on again-t ah~nlca~. att~ck ~nd h~n ~n Sound ~o ra~u~t ln l~o~d tr~porl: prop~ a.
Tl~o ~e~-nt ~mnntlon ~o relat~a tO ~ rO'J~
gunrd ~ whlo~l aro part~ tly ~u$'c~ ror ~
1~ t~ laly~ o~ c ~la-. ~ hlghly ~at~r ~voll~n, hydro~hllic l~y-~ ~n ~ d b~tY--n th ~d ~An- A~ h4 ~lr~t blp~ n~ to in~u~o ~rc~or ¢onduc~ ity ~cro~ #lo g~rd ~r~n~-~lr~t n~ ~bly. Al~tiv~ly t~ gu~d ~l~r~n-30 ~y bc tr~ to c~e~t-~ the l~y~roplllc ~uxf~c~
r~qulrcd. ~n lth~ c~c~ Iccy 1~ cognlt~n ot tAo n-cu~olty Or d~lng a hydrog--n ~on conduc~lY~ lay-~r butY~n~n t~ g~rd ~nd bi~lolor ~ran-J ln ~eok ~cl~
~ya'c~. No ouC~ cor~duc~:lvc l~ror i~ ro~ir-t in t~
3S ~ er~d~ Iytla eY~ene o2 ~trong a<:~d~ ~o SEP-~a-l~91 15:0'' ~C~ ~LLIcB 5IGNhL ~ ~i DEFT. TO 91~ 3g86~1 ~.05 ,., ~ ~ r- 2 ~

slloDbr~nea r~d only b~ a~o,c~'c.
~ 8 ~ppara~ua co~ri8e~ at lea~t ono l~nit o~ll ~Dprl~inq~ a~ 1~aot on~ ~t ~n~ c loast c~nG~ ;On s~ CtlV~ 1~YHr S~ed ~ror~ th~ gr~up 5 co~ t~n~ o~ an ~n~on 8~1eCt.~ la~r and c~ion s~ e layer. rhere i~ at lea~ ~ne se~ar~te gua~d an~, p~-~o~ y ~ ~onopol~r ~r~n~, a~ja~nt ~o a~ lea~t on~ rlrst n~ran-. By ~onopo~x ~r~n~ lt ar.t ~t~t t~le ~8~bX~IA~ tl~r ly p~r~it~
lO p~r~tlon o~ on~ typ~ ~ lon. ~t ~ thor ~n an~on oolocti~ nbr~n~ or ~I cntion ~l ctl~ no.
d ~r~ne ~t~ in cont~lct: Y~th tl~e r~rs'c ~r~no ~lon~ layar o~ r~ w~o ~o~oct~vo to tls, trp- o~ lor~ ~ t~ zonapol~ gU~ n~n~
h~ ~lr~-t ~ bran~ cdn ~e ~ bipola~ ~bran~ h~vlng eation 1~ B~ layE~r and an anion ~ ctivn lay~r.
;-'b~lar~ th~ tlrst ~ a b;~ r ~brano, th~
~uard D~llbr~l~l ~d ad~c~nt l~yer o~ a ~ r ~o~ br~n~l ha o tho ~ rlty- l~C~ r-, ~n ~nlon ~0 ~ ce~ la~r of ~ ~po~r ~ra~ 1~ ~ds~ont ~o ~. ~onopola~ nlon -l ctl~ guar~ ~br~n-~alt-rnati~ ly a c~tlon ~ r o~ thn bipol~r ~Dbr~n~ ~ ad~a~nt to a nonapolar catlon ~el~ctl~-gl~ard ~r~no.
~n ~lt~nato ~od~n~, tho ~!lr~t ~ c~
bo ~ o~t~on Do~na o~ as~ ~or. ~r~. ~-rlt ~e ~r~e n~a~ a oatlon a~ ~o gu~d ~n-o a c~tlon ~ . ~ero th~ ~r~t manbr~n~ an ~nlon ~ran-, ~n t~ ard ~ran ~0 ~ n ~n;on A~l~t~v ~bran--.
St ~o g~o3i~so~ to uo- lo~ ng ~
~n~ r~ ~r~no ~ ~ y r~ g~rally ol w~loally otamo ~ n~ ion tran-por~ ~roportl--.
I~utr~ braLn~ ~ud ~ d on c~llulo~
35 ~c~t~t~, poly~inyl ~lcohol ~.r polyel-ctrol~ ~onp~

SEP-3~-19gl 15:08 ~-~0~1 ~LLIE~ SlGi~l~L LflW DEPT. TO ~1~135~3386q :'.09 2~5~4~

c~n ~ o ~ used ~ c~nt to ~e~brnne~ or l~yer~ o~
oa'cionic~ or an~onio scl~t~Yity. ~n unit Ccil~ ot th~
pre~en~ SnYent~on we~'ul rc~2~ ele~ aly~s~ t~l~
m~ran4s ~ Pr1 ally ~llgned to a~ e$on or 5 anlon~ t~Yard~ no~e an~ c~tlon~ rds the ~thod~ rc ~c coqDp~r~nts ~t~r~en ~h~ ~e~lly ~lign-d ~br~n~ ~ h~eh ehe 4e-~ eoltlt~ons ~e ~cd and ~roDI whlah produot ~olutlon~ ~ ro~ovod.
g~rd ~r~no ay ~ d in alJloot any o ~l~c~rodl~lycl~ c~ll ccxnrlguratlon lncluding ~l~c~ro~aly~s u~-t~ and t~o and thre~ co~tDIlant ~oter ~,~llt'c~rJ.
~ ho ~m~n~ fl~ sh~-t c411~
nor~ally u~d bu~ co~ld be o~ ov~n qreater advan~aqa in 15 ~p~ral uo~ c~ n~ a oinql~ no 1~ rgor ~na ~e ~p~c~ont nlg~t ba nor~ dl~lcul~.
rho prouont lnvon~clon lrlcludoo An impro~Hd ~nthod o~ ~lo¢t:eodl~lytiL~lly tr-~tlng ~n aqu~ otr~
oont~in~ o~.~ct~olyt~, ~oh ~ ~n aqu~u~ ~lt ~0 ~olutl~n ~ an cLecl:rod~s~yolJ opp~tu~.
Plg~ a ~c~t~ ~avlng Or ~n L-ctrodlaly~lr ppa~tuo ~ t~ pr~oen'c lnv~ntion.
Plgur~ ti-:: dra~lng ot ~hree ?.5 ¢a-p~rtD~nt ~l~ctrod~alytlc ~t-r ~lltt~r ~ tb.
colnt ~n~n~ion.
F~ 3 1~ ~ ac~t~c ~Y~ng ot ~ two oo~p~r~'c ~,-e~ ~pl~ r.
~atic dr~ g Or ars 3Q ~ ct~ a~ G ~tJC)~ d. ln t~lO EX~P1~J~
Pi~ 5 i/~ a ~c~t~c t~ t o~ yo~
U040. in ~-- EK~P1~.
Plg~ a ~ono~t~o draYi~ or Ul- appar~tu~
uo~d to t-ot ~o potontl~l ~sop u:ro-~ ~br~- ln 1 g ~ca~pl~ ~ .

8Eo-30-i99115 ~8 ~?OM ~I LIE~- SI~N~L ~IA. ~JEF. To C1~1a5S3Y86~ 8.1~

2 ~ 4 FLg~ ~ L~ Lart ~ow~ng ~o C4~ ntla~
acro~3 thH te~ ~pparctu~ c~ Figu~:~ 5 ~hen ~n untr~atad, tr~t~d and n~ guard ~r~ ar~ use~d ir ~odsu~ acetate.
~n en~ Figw~e~ th~ follo~ing t~nspor~ ~o~ ntion wan us4d. M~or ~dQ6ired~ t3~ansp~ ia in~lc~tlsA by a ~nli~ arro~7 Th~: pros~nt lr.~e~tion ~ tood ~y tho~
~killecl in th~ y r~ ro~ce to t~ ~eoo~ny1ng P~
Figures 1 ~ougl~ 3 ~lu~r~t~ ~l~troCll~ly~1 apparatu~ ln w~l~b tl~ pr~nt imen'cian ~n b~
18 ~n ~l~ctrodialy~i~ app~r~tus col~pri~ln~
~onopolar ~n~on ~ a~tion ~rane~ gure 2 lllu~trate~ po.r~nt o~cerodiAlys~ w~t~r ~plit~ar ~4~prl~n~ alt-rn~ti~ ca'c~on ~ipol-r and ~n~on nenbrane~ 3 lllu ~ra,tac a two CoDIpar~oR~ ~atcr ~pl~tor ~yri~ng alt~rn~ting ~0 catlc~ n~ bipolar ~ an-.
Tho onbodi~nt~ ot Fl~ h 3 or~
pr~nted ~or 111u-t;rati~o ~o~ ra ~br~ r- ~ra;~rably u~ed ~ao¢n~; t~ blpol:~r ~br~ ln ~lectro~ r spll t-r~
2s ll~uotr~eod '~ ~ thr~ cc~p~rtD~nt w~t~r lpl~tt~r n ln r~ 2.
'rho ~uard ~R~r~ne c~n ~l~o ~ u~a ~n t~ro cc~partm-nt Yat-r ~pl~tt~a, ou~ ~ hown ~n rlg~ro 3.
Sh- p~oo-nt i~lr ntlon $- ~lrooco~ ~o t~l- uel- o~
gu~rd ~sano~ to pro~ront rlul~ g~ t~-p~ y opor~elvo ~tlr-t) ~ lop ~ ledc or hol~ t l~a~t on~ guard m~obrAn~ pl~ c-nt 'co a ~irnt ~nbrdrls~ ~ in t~ 9X---nt ln ~tlon the teml "od~a~en'c" with r~p-~n t~ a gu~rd ~r~Lr.~
ml~nn~ t tn~ rd 2~c~r~n~ t~ly n-xt to 3-1~91 !5 ~ 31? h_L ! FL~ lflL ~ Rl'J rlEPT, TO ~-161~;6~ 69 P. 1 ^

~3r3 2'~1 th~ ~ir~ an~ ro~orably, th~ ~rd ~an~
in ~:ontact ~th th~ ~ir~t ~e~rans ~ubatantially ~YFr thc oc~ ro ~r~a t~rough ~:ich ion~ p~s~ 'eo ~}na~ the ~axi~wll e~1~1cn~l and p~tion o~ ~erB i3 no 5 ~unctlon~l co~ar~ent ~e2Y~ d~acen~ me~r~n~c.
ar~ ~brare 1~ ln corta~ wl~ tn~ r ~eEbr~n~3 alc~ng t~e l~yer o~ t menbran~
A~l~ctllre ~o th~ ca~ typ~ of lon~ ao tha guar~
~e~brano. G~ rd ~:r~n-J ~hid o.re ~dS~celnt ~nd ln ro oontao~ A a ~lr~ ~ no ar~ ul~r~y u~
i~ a nu~b4r Or 8~B~ ~uch ~ ~trong ac~d or 3:8 zlod~rutc ~cid c~r ~ qctww. 1~ ~prcn~Q~Pnt ~ th~
prel~nt in~ -nti~n i~ u~d'ul in ~ ctrodlalytic ~par~tu~ regardl~ o~ ciflc conflguration.
lS ln th1~ l~ciAl c~e ~-t thc d~cerodi~ly~e tre~en~ of w~X aai~ i~ nae ~ fo~ hat in ~C'Sd ~ guard ~br~ncc v~ dnor~nt to tn~
r~r~e a~r~ v~ ~ con~uct~v l~yor pr~v~mt ~h~
~o~atlor~ n-con~uctlv lay r. o~ ~cid whlch 20 q~eatly ~1C~ H th~ pot-nti~ drop acro-~ tb~ ~y-~Q~.
uara ~ n~ ~ay b~ ~ ~nt, or An A~l~e l~y-r ~u~t ~ ~d~ad b~n th- sr~Sd a~d bipol~r ~r~n~ O adb~ion ~tw~n uL g~r~ an~ ~lr~t no~ran~ a~c- a~ a sondu~l~ ~l~g, ~ e- a 25 t~l~ ~ntl~ Op bCrO ~ ctro~Lalrtlc un~t.
Tbln Q~d~nt Or ~ pro~-n~ ntlon lo u~ul ln trodl~ c ~ppar~tuJ ua-~ul for tro~lng ~k Acldo r~lg~ lc eonrlgur~,'ci~n.
rn s~ ao~a ~y~e~ ~o plac~sl~ ot ~ g~rd 3~ no ~d~aC nt eo an~ os~a~ ~ ltb a~c l~ot on~
tiret ~ran- ~l~.-d rrol~ blpolar, clltLon and anlon ~r~ldct~ro n~rane t ~ con~ct~ Y-r i-~o~d b-tw-on ~,~ ~o ~raJ-~- lc a~t~
P~-s~ r th~ r~ 3-a~r~n- io ~ ,polar or ~
35 cat~on ~ OtlVO ~ano ~ c gu~l ~ c~tlc~

~Er-3~ 91 1'-:139 ~?1~ L.iEi~ 615~L ! F!!J ~EF;. TO _16105639~6'l r.l2 ~3~D~

o~ ~ctlV~ 3branQ~ 06t ~ra~ ly tna ~ir~t m~m~r~n~ i~ a bipcïar ~em~ranY.
Ay tr~ nt wh~ch ~ould alter ~h~ guard s~e~rane ~o produ~e ~ hydroph~llc ~ c~ which 1~ ~nc~ o~
5 ~igr~tln~ aoro~ ~br~e~ ~y be U~ . Pcoper a~nes1on loetween Ul~ guard ~ran- and th~ ~rs~c membran~ may b~ achiRvod by~ a~lnq a ~atlng o~ "glue betw~n tha mH~branes or b~ ing t~ ~urfllc~ o~
the ~u4~d ~mh~ . A~?~ro~i~t~ ~dhorent lAye~ muot 10 bo high:~y w~t~ awoll~n 'n~ le~t ~bout 50~), ~ln, h~ghl~ eonductive, h~g2tly ChaK~ n~ rlxo~ ~etwe~s~ ~o su~r~ ang ~r~t ~r~na~ ~uch ebat tJ~ ~on con~uct~
l~y4r i8 ino~pablQ or p r~aelng ehrough olth~r m~mb~an~ .
For ~ , cn ~ro~ te gl~n ~y bo ~A~h by pr~cSplt~t~ng ~ ~ulfoz~t-d po~y-ullon~ ~olution ~n~o ho'c w~tcr. ~ho oo~loi~al cuap n~o~ $~ collectbe!l anc~
5pY~ead onto en~ ~irse a~ vla ~ny conv~nt~on~l su~:h ao ~ ~o~l, bn~ o~ ~p~y~
~o Mlcrop~rtlcu~a~- ~on ~xch~n5p r~n o~ ~hQ tyz~-a~cribad in th~ ~lr~t ~Y~pl~ 02~ - Pnt~ o-

6,3~9 ~y ~l~o b~ W~d Ae ~qlu-~ ~een ~o gu~x~
~nd rlr~ ~r~ne~ " lay~ c~n ~ c~tod onto ~tb~r ebo ~r~ or t~ rt~ ~r~n~.
~6 ~rho ~m~ t~ ~no ~o t~-n plac~d on th~ c~at-ld ~l~o or t2~o coated ~br~
e ~ Rr optlon ~ o ~d~ a ~xr h~h c~e~tY
~ulfo~ oly~ on~ o~ o~er h~gl~ly aul~on~
po~ar layos ~a ~ g~rd D~n~ rin5~ c~-tlr~. A
30 l~y~r Or eulron t~d polyetyr~ o~t~a on~ce~ ~
~ul~na~cad poly~ul~on~ y~ a gu~r:3 1u~br2~n~ Y~ng gao~ adllc~l~ propo~ and ~ ~tnbl- ~o~ontial ~OP
~hon ~t ~ 2c~d on o 2irJt ~n- ~1th th- nigh ~paol'cy layar ~d~L~t to ~o ~t ~ru~o~
~ltorn~tiwly, ~n~ g~ ~br-n- ~y b~ ~ltHr-~d s~p-3~-lss1 15 ;~ F2a~ L~; E3 ~ll3~L a~ EP, . TO 916135639869 ~.17 _ .
2Q~2~

to in~ure pr~per adhe6~0n. Por hxamp~e, th~

)~ydrophilicity o~ t~e ~ rd ~aLbrane ~ ~e $ncs~ ed by wiping th~ adh~ing 3ur~a~:a o~ the guaJcd aD~r~n~

wltn an appropri~to Jol~ nt ~uoh ~ ~ N, I~ hyl fo~ld~), ~1~0 (~i~tnyl~ulroxi~e), or ~ æethy~-pyroll~ons~ rollo~d by qulc~ quenchlng in ~ter.

P~ disl~olUtlon Or 'eh~ g~r~ nh follaYsd w~t~r ~nchlng i~ o r~ult ~n a ~urf~eo layor w~tn h~gk~r wator con~cont ~n i~ ~or~ed by 10 wlvont ~vapc~r~tlon. Cu~rd ~ru~o~ ~ay al~c 1~4 Wr~ ~c i d a~ c~ vat~e~ . It ~ ~lie~ed th~t acld l~ rYlon ~olla~red b~ ter gu~ chlng ~nt:~ea~ th~ l~ulfonlt~on a~ the guard ~ran~.
C~r~ ~ust ~ ~olc~n ln ao~ly ~ guard-S5 ~lpolar ~ane ~or ~3a in ~o~x ~c~ ~y~c~ Ie isvery i~porta2t to J~Voi~ ~r ~ b~ ot~ta4~ tb4 two ~r~ , ~o~w~ 41r bub~ rlAt~rl oot~ whQn a curr~nt is p~oA acro~u th~ c-ll to ~oru a ~an-~:ol~ldUCtlY~ 0 ~hich, cor~s ~ co~dor~bl-~ Postion ~o o~ th- ~ctlY- ~ sur~n~. A~l~ Lon or l~rAl ~unt~ o~ ~t~r ~r ~lutc olccero1ytc ~olution ~sn th~ e~o ~o~br~r.~ oan ~ ~ ~ ali~ tlng alr . Yo~ u~o in wo~c aala ~yc~, tho 11qui~
io~ 1- ~o~bly ~ w~ion a~ colloidal ionlc 25 ~oly~ar or nlcropar~ a~e lon axc~ go ~nln.
ma g~rd D~br~n-a ~cr~ 17~re navc p~tlcul8r Utlllt~ in VaJ~C aa~d ySS~ whor- co~l~t~
ad,b~c$on oS t~ Slr-t o~br~ i~ cr'tic~1.
A~ us~ ln tbo ~a~-nt lnv-ntlon, th~ cid 30 ~dna ~n al::ld ~ a p~a o~ ~bout 2 or noro. Son ~n~lt ~y b~ dhrl~ ~Y~n v~ 30dU~lY ~tror~
AC1~1~ aUCh a~ ul~urouJ o.ei4. Whllo tna gu~d ~o~bran~ of t~o pr~ont ~n~v-~t~on ~or~c in ~t~ong acl~
n~ ~ aO~lon or u~ n-o 19 not r-guir-d ~or 3~ ~tre~n~ acl~ nd ~ moly o~ tho gu~ brano ~C~ ~IJ! I --' L;CIJ ~ HL _H~I vtr ! . I :J ,L~l_--o~

2~;2~

~y~t~U y~tch dc~ not requ~ eondue~ e l~y~r ie e~ r. Aecor~lngly, D~an~ havlng ~ lonloally co~duc~iv~ layer ~re pr~f*rred in ~alc acld ~y6~tHmU r ~hll~ non~t~te~ g~Ar4~1 ar~ ~rer~rffS rO~ 6tr9~ aci~
5 ay~tem~. $1 e apparat~;~ di~elaaea ~elow are ~t~le ~o~ h ~eak arlG ~trong acl* sycta~-lycis ~ppar~tu ~ n~ t l~st one unit cdl. Tn l~lgur~ 1, ~nit cell~ ~re str~t~d~ ~ch compr~ng ~ on ~ nge r~br~n~
lo !+) ~n~ ~n ~ion xchang~ ~ruu (-~ 28, ab, cmd 2b' r~ep~cciY~y~ ~ ~it c~ ng~ o ~ina ~lt~nating dilu ~ oo~p~r~nU~ ~D~
concontr~on oonpart~onts ~C).
'rhe unlt a~ hlch in pr~tlce ~y num~r up to 15 t~ hundrHd or morQ, 3rc arran~d bQt~ n ano~
100 ~c.g., ~ tlnw~ nd ~ c~:hode ~-) 200 (o.g~, a pl;~nu cathod~.
An ~bodl~ nt Or cn~ pre~ t ~nvortlon la tl~
placoa~r~t ot ~ guard ~rU~ nt t:o at Iu~Nt ona 20 tlr~t ~ation ~c~lange ~bran~ and~or at loa-t on~
~lr~t anion oxchang- ~bran . ~rd m~bru~oll 3~ d 3a~ ~r~ c-tlon ~ n~o ~o.n~ d~w~nt to ~rot c~tlon ~r~no- ;~o 4nd 2-' ren~ctlv~y~ ana guu~d b and 3b~ a~ an~Orl ~l~anga ~S ad~c~nt to rir~t ~nlon ~ran~l- 2b an~l 2b' r~at~raly .
T~ ~pparntus ~ Fl~ uoo~ul, 2Dr Y~pl-, ~ox th~ roCo~ 41 ~Cld ~roV ~olutt.ono ~ lo~nq ~cld ~nd oalt. I~ op~x~tion, an ~u-oU~ ~oly~o 30 ~olutlon~ pt~r~y nn aC~ C ~o3.~10n, lo ouppll~d tv ~l~tr~ rln~ CC~np~nes ~), anCI an aqy-ou-301ution~ prer~rably ~ cldlc ~olutlon, i~ ~upplL~d ~la ~tr~ la to th~. concontr~clng co~art~nt~ ~C1.
~ o~u~or~ prl~lng ~t ond ~IC~d l~ pp~l,~ to~Ch~
35 dlL~ o ¢o~pU~ont (D~ v~ iro~ ourr~r~ t~ e~n ~ 5 1 _ ~ ~ 1 .L J. I --~ J =L, ~ J C r ~ c ~ ~ci:~ ~ . L_~

~4 p~s~d Sro~l the ano~e ~ o the ~ hodc ~0 caUD1ng hydrc)g~n ionB ~ om ~ch~ acid (~Deh ir~. the ~ilu'c~
c~mpart~nt ~ nd in th~ ~lec~ de rin~P) i~nd ~Qtal lon~ ~M+~ o~ t:h- JQlt to ~gr~ oY~rd tl~- c~ho~
5 200 . ~ocn ~U~ 1 0n~ ydrog~n lon3 ~r~
~Apab~ p~ ing thso~ tlon na~ra~ 7~ an~
guar~ c~tlon ~e~r~ine 3~ ', hydrog~n ~ on~ ar~
prQ~ ntially tr~n~ported into the conc~r.tr~t~ng ~::omp~ ent IC~ b~ s of ~leir iJ~e~ter mobil~l;y.
10 ~ultdneauElly, 2mions ;X-) (bo~h in the dllu~
eo~ rt~ent (D~ ~nd the ~l~tr~d~ rin~ co~parto~nt tc to~o~rd ~e ~nodo loo, paBoing t~roug~ t a~ni~n p~ lo~ o ~ran~ antl guara an1on ~r~n~ 3b. P.cc~r~nqly, ln th~ conc~ntr~1ng 1~ compart~ntY ~ c~d ia ~orm~a ~an~ a s~11 ~ount ~lt) an~ in th~ dilut~n~ co~ent ~1;) ~ ~Clt ~pl~tQt ~alt ~olu~on re~in~ c ~roduct groduc~d ln t~ concentr~ting c~p~-nt (C) ~cypically a~n cont~1n llp tO at leae* a~ oS e~lo ~ acl~
20 t~s prod~ct solu~on, an~ ~y contain ~N ~uch au abDu 9~ or ~c~rr o~ th~ ~r~ acl~ reaction ~roduct ~r~ thH conc~ntratlng col~part~nt ~C~ n ~ithdr~ ria 11ne 5 and ca~ bo r~cycled ln w~ole or in r ~r~ r ;~na~tr~tlon ~r c~n b~ r~ovul ~nd ~S r-us-~d or l~old. me r~:~a1nir~g d~p~aed salt ~olut1Or t~ ut~ng co~p~ nt ~D~ chen r~oved 11ne ~ l c~ d t~ ~t~ler proaos~
~ h~ guar~ ~e~bran-- a~ pre~nt lnv~nt~an c~n b~ uced ~ rater ~1itttl~g w~lbrano~ uo~d ln0 1~ctrodi~1ytic ~r ~pl~tting pro~oc~ U~erul la Y~t~r opl1':to~ c~n S.~ludo e~o ~o~part~nt ~at~ ttor~ ~nd ~ coJp~rt_ nt w~t ~plltt~rl~, a- ~Iho~n in F~gure- 3 ~m~ ~ r~y~ctiY ly.
Th~ pra~nt ~n~r~n~ion ~ tr~tod usin~ a thr 35 co~p~rt~nt l~at~r ~litt~ tlc~11y 3ho~n Lrl _tr~ L~l ~ 1; hLLIL:U ~ lL~Nh'~ _hi~ U~:r I . il.J ~ JY~ Y r. Lt F19Uo-4 2. ~ ~2~0~ GO~lpal~lUln~C el~ odi~i~ytic: wa~ex ~pl~tt~r co~p~ ;es: a~ l~a~ on~ unit c~ IJC~. ~ach ~ni~ ~ll c~pr1~ s a cati~ r-:3plitting, ~nd a~i~n ~ ano ~ ngod in alt~n~ ~aion ~o d~in~ Gl~ ~a~, ~nd ~alt ~$) ~ nt~.
~ploy~d ls~ ~a~n ur~ o~ ea~ ~or spLi~ing ~at:or lnto bydrog~ a~d ny~roxy~ ~on~ ~wa~
spllttin~ ~rane~ os~ pre~e~ri~ly, ths ~ n~ r~r ~litt1nq ~t~3r into hyd~gen and h~oxyl io~ i~ ~
lO bi~oi~r me~an~. iixample~ o~ bi:pol~ ~ ar.~ ~ h ~x~ ~a~$ioul.~ly u~X ~l lnclud~ ~o~ ~0 S. ~ae~n~ No. 2,B2~,~P~ t~ Od~ ic~
x~fer~nca ~o wa~c~r ~pli~ n~ gsnerally~, ln U.
~a~ Ng~ 4, ~Z~, 04~ (w~.~r~ æ~
lS ~1~18~ ana~ r ;~ U~ P~terl~ ~o. ~ 6,as~
~Yhl¢h d~c~ t b~pol~r r~ br~ne ~d i~ ~o~t pr~ r~ o~ar~ ~ny Dl~hn~ abl~ o~ ~pl~tt1n~
w~ar i~o hy~r~en ar~d h~xyl io~ ay ~ ~ or ~x~pl~, ~p~c~od ~p~ anion a~ ~aeiDn ~a~D~ara~ ~a~ ing zo ~ er di~o~ ener~eweon. ~o ~ Dr splltt~rly W~ in ~ a ~lar ;~æ~b~
~h~ ~tlom ~x~ban~ ~mbr~a~ e~ploy~d in th~
el~ctrodi~ p~r~tu~ p~ise~t inlrer~ ay S~ ~c~er~ 4idie t~.~. . pho~ n~a g~oup~
~OF~t~iRing~ n~J].y ~C~ u~Pf~ grou~-~nt~lnl~~ l on p0~s~ tiva ~x~r~o~ or ac ~ d i~
~ ors~ ~n c~t~ p~ n~.
P~ ula~ly u~ul c~ n ~ n~ ~r~ ~uPos~
N~:~lon~ ae~ lu~roc~2bDn ~an~, e~eiall~
30 ~lon~ d 3a4 ~tl~ ~r~n~0, More ~xo~o~bly, tho o~lon ~b~ a~ o~ ~ co~ si~ion ~n~ a~n~ u. s, P~
73~ 764.
~lon ~bran~ u~ l in ~ ~lect:rodi~y~i 3S ~pp;~ratw~ pre~ne lnYen$~ior~ t~o~ y/ mildl~

~Lr--_~J--L~71 ~ B I hLL~ ~LLJI~HL L HW LLr: . IU ~ltl~ irJ ~. 1 ~

o~c w4~.kly ~ anion perr6~10c'ciYo ~rano~. U3e~uL
~1!3~rr~nP~ ar~, ~Or eXa~P1~, TOYO ~d~ 2V~13 Or AS~a~i G1ZIY~ Ca5PRr~# an~on per~u~ Y~ br~n~s 6~1~
und~ the tr~de n~m~ el~or~ V, ABV or AA~ o~t 5 pr~fer~ly. th3 anion ~n~elect~Ye 7~br~ u~
t~ pra~ne lnv~ntion are tho Ae~h~ Clasc Aav bran~.
Pigurf~ ~2 wh~3s~tl~11y lllu~t:rAtQI~ ~ d~ælgn ot a thrt~ compart~er.t ~ tr~dalytlc ~at--r ~pli~tsr 1~ ~mp1o~ to r~cD~r ~n~ regRnerate aci~ hnd ba~ fram ~a~t s~lut~on~. A~ UCt~t~d, the ~hr~e comp~t2ent elcctrot~ialye_c wat~r ap1i~t~r co-pr_ses, i~ aerlQo~ an anode 300 ~ 8 P1~e1nUO anO~B~ an~lyeo cc~p~r~nt 30~, unl~ c~ (UC) oS alt~ ting b~
r~1, acltl rA~, an~ ) co~p~rtoen~ c~th~yt~
co~p~rt~r~t 40~ ~nd a ~ o~ 100 ~-~.g., a pl~tinu~
c~l~hod~ U~ ld cnd Jal~c CCnl4~nt~1 0~ th~
t~roo co~p4~0~t Yt~or ap~tter ~llu~ 4 ~n Y~guro 2 are d~fln~ by ~ llty oP ~i~lly arr~nq~
2c ~e~braneD ~IB ro~ eJ ~ ~t~ p~el.~ o~rane 1~, a ~lpol~r ~an~ ~loc~-~r~ne ~a, ~n~ on ~ cti~ n~ l~.c~
Although rlgur~ 2 ~ho~ tour ~--rlally arr-n~ed ~ran~ e th~e~ ~t ~ trodl~ Lc vater 2s ~lltt~ r- do~lned ~y ~ pl~a~ltY oP ~ t colla, o~ t ool~ ~UC~ ¢o~prie~ n~on l-e~4~, -a~tlon :lle~rane nd a blpol ~rnno tar ~qui~lant ot~ctur~o capabl~ o~ plittlng ~tur ~n~o l~yJrog~n and h~droxy~ ~,ono~ improwr-nt o~ re-~t o ln~v~nt~on ls ~t ~a~t one and ~r~eralbly OAC~ C~l~
h~ n~ o ~ono~ r ~a~on ~d ~r~-~ zs ad~cant to aat~o~ l~y~r 0~ I~lpola~ ~o ~
~n acoor~anc~ p~o~orrod ~odi~nt o~ tho pre~nt inY ntl~n, th~ n:~lytR an~ catholyt~l 35 camprlrtm~ntYI contnin a ~alt, ~ or ~ld ~o~u'c$on, 3-~gl lS~l QL'_I-3 Si~N~L ~ EFT. TO C161356~9æ6c P la ~ 2~2~

tha ~Cl~ (A) os~d ~ae (33 comp~rt~n~6 initi~lly con-~ln a ~quid ~:o~pslJln~ w~t~r, ndded Yia 13 and 17, rerdpect~ J~ a~lt 5 coDpartJ~nt Lniti~lly ~Gntains salt ~olUtinn, ~dsd v17. l~ne 10. Split~inq o the s~lt into ~ tn~l b~ c~nc~s l:~y applyir.g a di2~ect c~rr~nt thr~ugh the w~sr ~plltter rrOn ~ anc~do to th6 cothode.
~n ~he Acid co~aent ~AI ~h~ o ~up~lied with 3uia ~o~pr~ nd, pre~os~ly, ~n lO aloctrolyto, hy~rogon ions ~ v~a tnz ~unct~or~ or t~ ipolar ~b~n- llb. ~o hydxogon lon~ pasq through gu~rd n~br~o ~ ~o the ~cl~
co~pArt~nt ~A), Sl~ultan ou~ly, anl~nl ~a~ nat~a X
Ln th~ dr~wlngs~ the ~lt (o) ~ port~;d acro~s 15 ~ho ~nlon ~nbran~ lla ~nto tho acid comp~rt~nt The re~-tion o~ tho hy~r~u~ h the ~n~on~
y~el~ ~n ~oid ~rodua~ x. ~ d~o~gnatlon lr ~
or !IX) r~2~ no~ only to ;~ v~l~nt anlonG ~t ~l~o ~o ~ alen~c anlon~, ouc~ ae ~ t~ n~ ~rl~alont ~0 anlono, ~ucn ao p~ph~t~, an:~ ~zlx~ur~ ~h~r~o~, Cat~wn~ ln tho ~alt e~part~nt ~ ultan~oGoly p~ tl~ 3h th~ ult~orl ~br~n-- ~lel to the e~tholy1:~
and ~ro~ anol~ to tho ~a~ B eo~artu nt. Ir~
) eo~o.rt~nt, e~tlon~ ) Digrat~ throu~h the ZS C~lt~o~ ~r~n- l~e r~act wl~ ~o hydso~yl iono (OH ) g~ te~ by th~ o1~ ~br~ llb to produao a 1:~4 lr l.~d OC~lUt~OA .
I~tal l~ ~O. to t~ eatholyt~
eompartm nt rron ttlC salt 9 ccnDc~rt~ent~ Aceor~lngly, 30 th~ ~nolyt~ ~nd aa~hc~ alutlnn~ ar~ typlc~lly eontlnuo~aely r~tcirculat~ rrO". ~ co~on ro~oir.
~ hc acid p~CdUC'C ~rom ~ ne (A~ 1~ romo~
vla 15, t~e 'o~o- produet ~ro~ ~cc c~p~rt~JIt t~
rYmov~cl via L8, ~ cpL~t~ a1t ~ lutlorl ~r~
35 c~mp~rtmcnt rs) i~ ~oved ~ia 12 .

r ~ y ~ rLL I =~ lL L~l~ L~ S6~ . 1 g 3 2 ~

~h~ lectrcdi~lytic ~ r splitt~r oan ~e ~p~rat*d Ln ~ b~tch ~ode, a cos~tinuo,u~ 8, 01;' ~ri~tion~
~cnar~or. Produot sc~ltlors~ or porcLon~ 3ro~0r le.g., w~en u~Jlng a ~e~ an~ ~lo~d apportlon~nt operatlon) ~y ~e r~cy~ or ~ r con~ ani~ n~ ~IC~lU~ lJ
or ierial f`~ ~olsgh ~imil,~r c~nr~ntE~ lna~
sho~ r ~e employc~. 'rhelsc ~ 7th~r m~clifLcatlons, ~hanger, and 31tor~t.ion~ t.o ~he de~gn D~! ~a wa~a~
opl~ccr will noc ~Efc~c ~c ~opc or tno inYcntion ~n~
will ~ obv~ou~l tc tho~- o~ ordin~y ~
Tha ~loctrod~alyt~c w~t~r spllt.-,-r ls or~ln~xily fwppl~d with ~ dlrect curr~nt rang~ng r~ro~ ~bout 30 a~p~J~t;' (~p~roxi~ely 300 AJ~) t~ a~ut 200 ~p~*tJ
~proY~tely 2W0 ~ ?, pre~r~bly ~ro ~b~ut ~0 A~ft~ ~a~?roxls~tely 30C A/~) to a~out 120 A~ft~
~aFpr~Yi~t~ly ~L200 ~;~ ) ~p~ o ~ r ~pl~tter non~lly o~er~ttc~ at 2 ~I~XGt~e 0~ ~hreen ~ut ~O'C. ~d ~bout ~O~C., vi~ ~ t~per~tu~ r~nqel o~
botwcon ~bout 30-C. ~nd 55'C. ~q prorerre~.
~igur0 3 s~ws an ~n~aC~ v~.~ o~ tt~ o ~o:op~rt~0t water oplitt~r o~ ~ pr~ cnt ~nv~ntion.
The t~o s~ r~ent vatcr ~pl~t..~ ~nclu~ ~t le~
an~ unit sell vh~ch eo~ri~ co.tlon ~xa~an~o D~ron~ .e' ~nd ~ bip~}~r ~r~ . C~ion ~5~n~o ~lo ~ C~ 500 ~s~
tr,o C~t~lOCl~ ~00 rro~ lt coll. ~- ~mlt cQl1r ~r~
~rra~s~ to ~ lt-rnatlng ~ci~ cc~rrt~Ynt~ tAt ~nd b~-t ccop~rt~ent T2se unlt c~ ~ in practlc~ m~y nu~r up t~
30 'cwo ~undrad or ~or~, ~ro ~ l ~tuc~n ~n u~ t~l 500 ~e.g., ~ pl~tln~ ano4o) ~ ~ ¢~tb~ode (-1 600 (~.g,, a pl~tinu~ ca~c4od~).
Gu rd l~-~br~ 12~ n c~eiOn ~xchang- ~brar.
~d~cent ~nd adhor~nt to 'cha c~ion l~ro~ 0~ blpolar ~5 ~mbr~n~ lllb. ~h~uld l~i~ol~r ~ no 1113~ ~ro~, SEP-3;~-lq~l 15: 1J ~ .L!E3 .51~ L I ~'J ~L~ IU C161356~ Y ''.~

2 ~

lg ~u~rd ~o~b~D.n~ 12E 'IQU~ rev~ t~e con~eslts of th~
acid com~a~on~ fro~ x~ng ~itn tne conten~ f n~igll~or~ng ~s~ ~o~p~r~c~Dt.
Tho ~pp~r~tun ~r Flgur~ 3 ~9 us4~ul, ~or 4x~plR, S ~nr the ~cov~ry o~ acid ~ram s~lutlon~ co~pri~ing a ~lt '~X'~ of t:he ~c~d. In oper~tion, an aqu~ous ~l~ctro~yt~ olutiorl, ~rei!cr~blf co~ d o~ ~ th~
lul~tc or h~d~oxlde o~ upplio~ to clectrode rin~o oo~ar~c~onta ~, and ~ ~uaol~3 aolutior"
10 ~efora~ly o~prioing the hydroxlO~ of ll~ Uppl~Od a ~tr~a~ 7 and 1,17 ~ to b~a~ eo~partment~ t~ . A
~o~u~ion co~4priclng tsalt 1~ ~upplld to th~ ~cld co~pa~t~ent ~A) vi~ 113~ D~r~c'c currRnt i~ t)~cn pa~Rd ~rolD ~h~ anc~de gO0 tu ~ c~thod~ 600 ¢~ in~ w~ter to plit ~t t~ r ~rane, hy:lrogon ion~ (t~) to ntroduc~d lnto ~he acid co~art~nt A~ h~roxide ~on~ (O}rl to ~ lntroduce~ intD tllO l~e co~partacne B, ~n~ ~c~l 1on~ ~K+) of th~ ~lt t~ r~t~ towar~
tne a~th 6~0. I~ot-~ th~ ~otal lon-~ JnO, hy~o4an o lon~ c~pabl-l o~ p~ir~ tbrough the c~tlon ~br ~n~ , lllc' llnd lllC~ ' . Anlon~ ar~ tr~pp~d ln ~chc acld co~par~nt ~ and ~ cl~ ~th t~
yt~o~cn ~ono gon-~tQd ~f bi~l~r ~br~no 11l~.
Accordln~ly"~cld l~- ~ornod in aci~ ~p~r~ant A, and 25 a b~cl~od stro~n 1~ prDdus~d ln t>~ae co~t~nt ~.
t~n ~t 1~ th- ~alt e~t a ~o~k acl~, th- hydrog-~n ion concen1:ration ln a~ld CD~P~rt~n~ nS 1D~ b~lrau~e Or tll~ lwr d~gr~o Or lani~tion o~ NX. I~oct ~ ~
corr~nt ~a c~rr~-d ocro~- 'cho ~t~on ~r~ c~ by 30 M~ ion~ ~ntii th~ ~ concen~r~tion la clu1to ~o~. Yor solt~ oY f~oak acid~ un ~oQtat~ or po~iuu ~o~ a, i~ po~aiblo to aonY~rt al-ost all ~9~) o~
t2~G sa1t lntro~uc-~ lntG ~cLd caop~ nt- lnto 4cl~ lt d~ir~ Dlte ol~ ~satol~ ~)c ~c1~, 8.g. XP
~5 Gr Ne~ , con~erolon o~ 90~ ol t~ ~o1t 11~ gonoral-y tr To -1t.1_.~5~q~ .21 ~e~ le. T~.e product rr~l~ aoid cs~ m~nt A i~; thar~
~ithdr~wn ViP linR 115. 1~1Q ba~ ied solutic~n r co~pa~tm~nts ~s) i~ rQmolr~d tria linee~ ~18 and li8'. Th~ gu8rd 2e~r~ne has~ ~ i'cs~ pr~y pu~ e~ to 5 pro~ e ~ ~e~cup ab.ould tha ~ipolar ioD~rane d~el~p ~ altlonally, ~e u~ o~ tha s~p~r~cQ ~uard mu~bran~ haYlng 1 on ~elec~ ~ ve pro~rt ~ P~ can ~ h~r hclp to con~rol ~e oper~t~n o~ t~e ~ trod~i~lytic a~ r~tus. ~y c~re~ully 6electin~ th~ d me~n~, 1~ the ~f~ic~oncy ~or gonc~ltlo~ ~nd p~ty o~ t~o pre~u_t acis~ snd ~ ~n ~e cor~ero~ aDa onn~noocl.
Con~ldor~cn oS cur2~nt ~rsicioncy~ expQn~a, ~lze ~nd tt~ boul~ o in d~srwinin~ ho~ ~sr.y Dnd wh~t typell o~ gu~rd mol~bran~ to U~ . A~ 'ndic21ted .S abov~, it i~ pr~lterabl~ ~t thc guard ~ n~ h~r~
highE~r p~r~abil~ty to ~t~ mes~br~n~ l~y~r3 to which they ~Q nd~c~nt. q~nn pri~y operat$ng ~unoe~on 6noul~ bo 1:ha ~p-,rative :l~ran~l wlt~
gu~rd nololcr~n-l~ boinq ~ot~ ~or suFport ana l~pro~ ne~
~0 1D ~rlcl~ncy r~t~r ~an '~ unct~onn~cy w~th regnrd to tho ~at-br ~olltti7~ apparatu~' go~l.
~ hcn ~--~blinq tl~ SUICX ~or u~e- othar th~n Y~X
ac~d ~l~t~ a taY alr bu~bleo ~y beco~ ppod nct~on~l ~t~.rano ~d ~hc gua~d ~r~ne.
2 S q~lo~ o~ 1~ ~ni~i2ed by l~r~ lc-tlon o~ ~ator or ~Alt ~olutlon ~o eh0 ~brano urtace- dur1n~
a~c~ly .
on ~ tacit ~or uee in a ~o~k ~cid ~y~t~, c~ra ~UJ~ b~ t~c~ to ~LYo~d ~pping ~r 30 ~bbl~ re~n t~ ~u~d a~ ~a~lon~l ~r~ n Ch~ ~e ~t YAe~r apLltting to ~!or:ll v~ ~c~a~, o.q.
acoelc, l~ctl~, or t4rs!l1c a~ta, high r~ anc~ ca~
r~ult upcln op~r~t~on ~:,f th~ p~ itting nYQn Yhon air ~ub~ ro ~l~ulncl~d co~l~t~ gh 35 re~lotar.oo i~ rorltly ello ~o~ul~ of ~ or~c~o~ o~

IjF~ J- ! ~? ~ J, 1 -L ~ I Gi if: L _~'.. J .,EF . T0 ~ ib ~ -~56~a~6'~ ~ . c~

2or32 ~cl~ ~tw~n ~hQ ~ipol~r an~ ar~ ~ez~sa~ Th~ acid laye~ tor~ b~:4uso o~ ~f~i~r~nco- ~n lonio tr3n~pox~
nt~r ~e~~Rn th~ ~~ati~n exch~ng~ y~r o1~ blpolar menbr~n~ ~nd th~ ~dj~cent ~u~d m~n~, In tho o~s~
S o~ ~tron~, hiqhly ioniz~d ~¢ld~, a.g. H~l or Hz~O~ e fos~t~on o~ lay~er i~ not i~port~nt, 31nc~ the~e a~da a~ hly oor~uotlvo. For~tlon o~ a lay~r o we~C ao~d i~ d~tri~ont~l to th~ o~r~tion or tno Y~t~
vplltt~r becausc w~lc ~cld ~ vcry low aondua~ivi~y.
o rt l~ ~Hliev~d th~t ths hydrophillc lay~r sr coating o~
p~cnt ln~r~ntlon operot~ to roduc~ or ~lS;~in~t~
'chio ~robl4~ b~ ~otlr.g ~ ~ a~ro~ Y ~cid1~, hig~ly 40neluotlY~ b~idge whicr~ bac-u~ o~ ~S;B Asgn ~ol~oular ~ight c~ n~poFt~d ~w~y rror~ ~ Sn~Qrrac4 lS bo~eon e~o gu~ na th~ ~pol~r ~r~no.
~huo ~ add~tlon o~ a hlghly ccnduc~ ~obi1~
intar~aCQ lay~r ln~e~ pro~ ion ~xchang~ Acroo~ the rolyt~c cal~, ~h~ o ~dglns~ ~ech~nical 8t~ng~, ~nd dtcr~ g ~ ood oY ~olution 20 con~in~ion ~I:OUla U~o ~i~t ~ran- break.
~ 61~ r ~f-ct ~- ob~ n anlon por~ uar~ ~br~no l~ Hnt to th~ ~n~o~
sce ~t th~ blpal~r ~bran~ r~ b~
p~o~uc~d ~ Tn ~l~ c~a-- ~--terl41a ~hloh ar~ ¢ondu~ivc 2S to hy~roxyl, lons oh5uld b~ u~d to toml ~e condu~e'~ c l~y~ twe~n ~o bipol~r ~nd gu~ ~lsran~
~au bub~lco aro ln~S~y ~pp-d"~t t~ey al~app~r durlng U~o n~ l op-ra~lon oS t~- ~taclc. ~tart-up ~t low~r th~ no~l curront d~n-lty ~y b~ n~c~y 30 ~hH ~tack pot~mtlal drop 1- too ll~gh ~t Slr~.
ollo~rlnq ~x~le~ u~ eo ~A4 pr~ct~co or tl~o praGont lnvene~on. ~e ~pl~ ~oul~ no~
con4tru~d ~o ~ ln~ ntlc~n t<~ anytll~ng 1~
than tha~ Jh t o ~ lo-ed ~r ~hlch ~ b~Y~ h~n ~!j obv~ to on~ at ordln~ kill in thQ art t~r¢t'~olo.

~ L~J~~ r~L ' r~! Llt~- I . IU --ltl~ Yi~

L~

Per~nts~ ~n~ part~ are ~y ~e~ht ur;l*o~ other~isQ
l~d~ ca~d.

Exa~pLe~ were ~ondu~ted u6in~ tbe olocero~ ytt c ~t~cx a~own ln Figt~r~ g . ~ho aE~Be~bly COmpriSed ~,W~ e~ld p~a'ce~ 202 aru~ 204. A ~lurality o~
~ ells~ R ~t~d bet-~e~n ~ n~ l anod~ ~0~ z~nd a ot~inl~so ~t~l c~hod~ 208. E~ unit c~ll ~s ~
oo~p~ en~ W~e4~ ~pllt~ng ~locl:rolala~ unlt lU cell ~USj. ~rhe repeat l~nl~ o~ ~he unit oall 18 ~own eo znce~pa~ a ba6e c~pa~en ), an a¢la ce.~part~ent ~ nd a salt c~rt3lent (5). ISac~ of th~-- cc~p~rtm~nt~ l~ ccneaine~ ~ith~n th~ ep~nlng ln gal~k~t. T~e~e~ 18 a ~'~rl~t g2~8~:-t 21t) lac~-t.cd ad~at~t tO anod~ 2a5. Ihla ~aoke~ cont~ d th¢ ~n~l~e co~p;~tnent 212. Th~s~ w~c ~ ~econ~ g~GXa~ 214 ~d~ae:~nt 'co en~ c~e:n~ 20~ a g~ cct cont~ th-catnolyto co~p~st~nt 2~S. ~t~ecn t2t- an~lyte ao~partslent ~ontairLlng ~aslcat 210, th~ catholyte c:03par~nnt containln~g ga~k~t 214 ~ the o~cr~tilre ~l~ct~ AlrtlC ~t~ak o~ ~lt~rnatinq i~n o~lect n~ ~nn~ ~nd qsd~-tJ h~ e VG~ 13 acit base ~nd 8;~1~ co~par~ents. m~ ~a a c~tion ~o~an- ~15 ad~ to g~t~t 210. ~~ fo~
~5 plur~ cy ~r rcpc-tlng un~ c~ uC~. e4ch unlt cell ('UC) containe a ~N ccl~r~ ) ln gad~.~t 218, An ac~d ao~part~nt ~A) in g~ t 220 and a ~lt c~pe~rt~-nt ~S~ in ~o~k-~: 222. 9-two-r1 g~X~-t ~18 ¢o~pa~t~uDt~ ;~nd ga~ 22~ (wid oo~ar~n~c~
10 t~oro w~ a ~ r ~br~- ~a4 wl~ tb~ ~nlon lAye~
~,clng to~ lo 206 and c~tlon ~ c~iv~ l~y~r ~al::inq tow~rd c~atho~ 20~. Tn th~ ~ca~pl~c o~
pre~ent inven~lon, a çluard Dle~ran~t 226 ~a ~ c-nt to the c~tion lal!~r o~ r ~r~n~ aa~ bctsr-en tne ~5 ~ipclar ~r~n-. 2~4 ~nd 5~1c~ o. ~ctw~ g~kot jEP~ g9l c 1~ LLi_~ 5IG~L ~_.qW DEFT. ~o C16~'5b3~869 ,-. c~

~2d~1 ~20 and g~k~t 222 ~a~ anlon m~ran~ 22~ rhs ani~n m~r~ne ~as ~'c~een t~c ac~d co~part~t (A~ ~r~ the c~1~ co~part~ent ~j. Ad~ co tna ~lt coD~n~4nt (S~ on ~4 ~ o ~ppoait~ ~rc;~ ion ~brano la~ w~
5 c~iDn ~cll~ti~rq ~ n~ 230. ~ho un~t cc~ Uc~ ls 6hown t~ ~xtend eron th~ baoE~ c4~rt~nt ~) tD catilm m~bran~ 230 ~n~ c~nt~ina a b~ ca~ nt ~B~, ~n ~eid oo~rtm~nt (A) nd a ~lt conp~ 5). ~hsrr~
i~ ~ guard ~r~ Col~ t~e ~c4 ~pa~en~ ~
1~ ana tno ~o~d ~o~p~rt~nt (a~ ad~con~ to tl~o ~at~ on l~y~r oS ~ blpolar ~bn~.
7cpanad me~ran~ ar~ ~r eac:h ~e~r~ne ~as 23 Cl1~7. Sha g~dc~ts ~era m~- o~ poly-tbyl~ ~nd con~i~t~ CUtGUt c~ntr~l port~ llled Yl'ch ~
:5 ~cra~n whlch f~ed --he solution com~art~nt ~nd ~n outa~d~ a~c~ ~ed ~or ~e~lln~ ~n~ ~or~lnq tb-~ ~ntern ~ani~sldo Yor acl~ 30 and ~a~t ~olu~iono. ~acn 0aslcet aloo lla~ a ~ls o~ n~n~ol~ Op~l~Jtg8 t~ carry rlu~ to ~n~ ~ro3ll lthor tt~ ~oid, ~ or ~alt ~nput 20 and vutput ~ liold~ to ~nd tr~ th- c~ntral acti~-~r~a hccordln~ to 'c~n iunetlon o~ ~ gaJk-tA In ~lcctrolo rin~ gsJks~ 210 and 21~ a DuPont Natlon~ 3a ~ran~ (2~ 6 ~nd 2301 v~o Plaoo~ C-rlt to ~CI~
pl~t~ SC~ t Cell5 (UC) ~e 1.nco~or~t~d int~
~6 t~ 4t~ ntlally ~ddirlg ~o~ th- anod-- ~nd A
~ 4a~1~0~, a blpol~r ~ n~ cLd gaJkat~ an anion 4x~hang~ 3~lDbrano~ a salt ~l~alcoe, ~ a o~t~on ~xcllan~o ~r~na. N~Yt to t2~- iln-1 cat~on oxohang~
I~Dbr~n~ wa~ p~acC~ ddltion~ ~ g~-kot o th~
3a tacK con~l~toll OS o~r ~ea co~rt~n~ but ~nly ~r~ acl~ ~nd ~1t ca~part~-nt~. m~ catlan ~rAne~
n th- un~.t c~ UC) ~-r~ producnd by th~ ~ thod oS ~J.
~. P~t~nt ~"3~6~, t~- bi~ol~ o- by ehd m~thod o~ U. B. P~t~nt No. 4,76~ n~ ~o u~lo~
35 ~br~n~ acoo~din~ ~co el~o 3-eJ~o~J o~ pr~parlng thu ~nlon OJ l ~ L L . ~IJ ~ I IJr~lHL HW ~Jt~ !, I U j l t L _.5t ~ t.Y i~ . _ layer o~ tho ~sran~o ~n T~ , Patont N~. 4,'J66,161.
The ~tH~ plac~ ln a ~ater Rpllttinq syet~ a~
sho~n in Flsur~ 3. ~c:h loop ~acid ~40, b2~e 14~ a~d ~lt 144~ consi~te~ o~ a recirculat$on ~ ~P~ to pu3r~p 5 ~oluti~n t~rou~n th~ ~t~ok at a~out 500 ~J~ n~
~o~aring pu:~p ~l to pu~ ~olut~an rros~ a ~oed rQser~o~ to ~t~.e recircul~tlon loop~ ~ho S~d o~u5e~1 ar~ a~ar~lD~ ~r~o ~ach a~ tho loD~. Fro~ ~ Slux andl ~o;npo~itlGn ~,e ~he o~ flo~ ePfici~ncy for acld 10 ~nd b~3~ ~r~duct$or~ could be do~ine~.
C~L~
~ h~ unit ~:nll UC Or Figur~ 4 W~ a~ d witno~t th~ guard ~ran~ 3~6. ~4 loop~ ~ro ~ach onarg~d wlth 10~ m~ Or dilutR XF llat~r ~a~ r~ to tha 5 ~ald c.nd ba~ lwp- and a ~aLution o~ 0. ~M XttO?
1. 06M ~F ~as, m~t~red ta thH ~a~t Loop. A~t~r r~nin~
~or 8 hour~ wit~ nt ~ 2.0 A the ~y~te~ r.e-lr 3t~dy ~cato . ~ otcntl~l drDp ac~w~ t~e s~ac~
11~ 0 volts. Th~ ~oi~ avQrrloY ~ 4 ~J~in o~ a. 78N
20 ~cld. ~ a~ rcrrl~ r~ .g~s g~ nd wao 1.60~N. Tt~ oalt ~v ~Slo~ r~t- w~ 3.304 g~ an4 va~
0.131~ nd ha~ u~tivlty o~ 0.0~1 ~/c~.
Ba~ l on ~ha ~troa~ analy~, t~R ef~ciency for ccid ~uctlon ~a~ 0.63 ~nd tha t~cier~ey lor b~ae 2~ I?rodu~tlon ~ 0.7~. Mol-t of tho di~-reno~ is ~oYn~
ln ~ho aold ~lnq lo~t ~n eh- oalt ov~rflow.
operatlo~ ~aa ty~1cal ~r ~t~ck- oporat~d und~r eh~-~con~ltlon~ ~ith the ~ran-~ Q~loy~d.
~0 T~ tdck a~ C~l~d ln Cosp~rativ~ o ~so~ d ~ut thls t~ ~n ~ddiClonal gu4rd ~e~ane ~26 wa~ pl~COd in ~ACn l~nle coU ~JC~ l~dl-t-ly ad~c~ to eh4 ~atlon ~ld~ ot tt~ blpol~ nn~
~hRM~a ~uard ca~,lan o~nbraneo 226 ln th~ drA~-ing w~r~: 2 3!; mll t~ c R~ re~ t~Ar Re~rch Co~r~ti~ R 10~0 L.Li~ L ~ J l~ I . !iJ `'lb~_~5.~ 86q '~. . '--i ~0~; 2'~ ~

strsnq aci~ c~ion ~ raneia ~aYin~7 a s~ooi~t~nc~i of ~ou~ o.~ o~ . ~e ~ c wae op~rai~ce~ ln a ~
r t~ Co2Dp~ti~ o ~ hs oalt ~od w~ +
o. 3~ ~o,. A~t~r 24 hc~rw o~ opor~tlon tt~o pi~tont1al d~op ~cro~ tho is~Hck ~ . 0 valt~ c~ ~ ~verS l ~w 1.3g g/~nin :)f 2.~a-N 3~atar~ x ~as ~6 g/~in oS norD~ ty 1.567. q!be o~ Yer10w wa~ 1.66 gJ~1n~ w~o s~ tlg ~s~c, ~d ~ad conduet1Yity of 0,043 c~, 'rJ~ ac~d and ~o of~c~enc~os w~re ~o ¢alculAt~ t~ be 0.7~. ~e l~provo~l e;tf1clency c3rpar~d t~3 Co~parativ~ b4b~y du~t w~tly to ~he a~dit~on~l f1uorlde in t.~e ~alt feed. T~a oper~tion Or ~h~ 3cack ~-~ not ~ rnibly ~-ran'c fr~ thc opern'clon o~ ~t~ vit~out th~ rd ~o~ran¢l-.
1;~ ~
T~ C~: rr~ ~p~o ~ alsa~s4~ a an4 a .5 cs~ ~1uwtor hc~ wr~ p~nch-d ~ n~ bipola~
~rane~ ta~c wa~ then r~usP~blod wlth th~
gu~rd n~r~ne~ ln pl~c~. A t~t ~ba~ a l~ak rat~ of 20 l~c th~n ~ c~d to ba~ ~n ' hou~ ao ~inu~a~
Wit21 ~ ~low to th~ acld of ~60 ~ nu~ ~d rlD S~ O
ehe ~a~e. Th~ lt3~k ~ra~ ~laa~d ~cX in ~ w~t~
~plitt1ng ~Iy~t~ a2l~1 o~r~ e ls~ ~unplo 1, Art~r Xl llo~ , th~ pot4ntlA1 dr~p ~cro~l~ th~ ~t~c~c ~a- 1:.9 25 val~r, thq acia av~rr~ 0- gf~ln Or 2.44N
~olutior, the baA~ cv~r~lo~ va- 2.6a g/~ 0~ 1.46!~
oo~.ut~n ~ t 5~ I.s~ q~ f ~l~gh'cly ~olc solut~on or oo~ y 0.03s~!~t~.
~urrent o~lci~cy ~ tbo ~e~ na baJIQ ov~r~;o~
t~ w~ ~ . 7 3 .
stack ~ ~ke~ apare ~nd reoc~ t vlt~out th~ R-lO~o ~ rbron~ . A 1~ ~o~t q~ve l~O
~Lf ~l~ rlow rro~ ~ld ~o ~aJo. op~ra~lon c,r th~ J~C-~
3 s wl~ such a larqo l~ loar.ly nc~t pa~iblH. T~

~2 ne~ thorefD~e we~ effecti~r~ in ~LlC~Yi~ls operatlon w~th ~n~a~ cl;ange in perfo~an~e ~her.damage to the ~lpolar Jle~rano n~ op~r~S~n UithOut th~ 'mp~ibl~R.
S lS~
The potential d~F ~rooo Irariou~ co:~inati~
bipolar ~ ne~ art ~r~nes w~ 14 ing ~SI ~rrar:ge~nt el~o~ adu~atlcallq 1~ r~
~ ~rane~ wQre ~pace~ apart 1.7 ~ ~y cylindriclll 10 ~ectlcn~ o~ 3.74 c.. dia~let~r pla~tic pip~. Each ~nct~or, ~a~ eq~ p~ld w~t~ iDlet ~lld outl~'c tub~ ~or Ad~ltior. ar.d rc~ov~l or ~o~Ytio~2. me ~ec~ nd ~eD~r~n~ wer~ h~ld in ~lace ~y ~Sd ~a~e~ 154, 154î to wnicn war~ a~ac~e8 a p1a~/nu~ tls6~ and a ~.5 platlnu~ a~thod~ 8~. ~a _3~r~ n-Y~ to t~
~1ectro~e~ warc ~uPont Na~ionO 11~. 1 mn d~ a~r qCl ~le~:~rod~ o~ ~o~ r~ pl~c~d ~n ~ehe c~nt~r o~ th~ t~o canp~n~ on ~the2 Jid~ o~ tho c~ntral ~ o ~ u~ ~ Yol~ga pro~Lc. 0.5 l~
2~ ~ cu1~t w~e ciroul~ted to ~, co~r*~r.t~ rlQXt to thu elootrc~o~ ~ra~ ~ co~on r~olr. 0.5~ 90diulo sul~at- ol~tion controll~l ~t ~ t~,l.peraturo o~ 30t 0.2'C w~ ci~ula~od to ~h~ pa~antc 51 ~d S~. A
hi~h ~ danc ~u~ti~e~sr Yae uaed to no4auro ~o 25 pot~tl~ n ~ ro1t g pro~ v~ an~ Ya ae a dlr-c'c ~-nk w~ p~oed thro~h tne c~ n-~-ntr~1 s~n~ w~ ~ n r~ov~ ~ tho prw~dur0 ~ac rop~a~od ~o ~-t -~bo ~so~tr1but1on a~ th~ solution t~s the ~cot~l o~orvc~d potenti~-l drop ~ould bo ;letoaned.
30 Tho n~t pot~nt~-l drop acrooJ a ~ r no~ran- o~ t~e ae t~De ~ U~ ln l~pl,a I Y~ r.d ~Lt~o~t gu~d ~br3nos i2~ giY~n :n ~b~a ~.
S~ guJ~sd ~3br-~n-~ ~Hr~- a~ ro~
3~ 8P5~ ~a-~ pr~parad ~y o~ on~lt~on ot ~701y~ulfon~ by SEP-30-l''ql '~:16 '~ CLLlE~ SIGN~L L~0 DEPT. TC 8161.5639~t9 P.-8 20~?~1 tha ~t~o~ dG~crlb~d ln ~. S. P~cont ~o~ 3"64.
The lon exch~nge c~tpaclty of tne ~ater~a~ w~ L.~8 meqt~. Th~ me~Dbrane thickn~ss ~a~ 2 ~Lls ~nd t~e m~mbrane ~e~ista~lce ~a~3 1.0 ohm-c~ ln O.g M ~ociu~
5 sulf~t~ ct 30'C. Tbc bipolar ~nc!l guard ass~ly w2r~
me~ured with th~ 6P6U ~e~ne ~n ths c~thode side of ~ha bipolhr ~e~rano. 8P~ was pr~par~d by wlon~tion poly0~yren~ r~ton-s ~ccordlnq to ~h~ procod~sr~
ln U. S. ~atcrlt ~a. 4,731~,7~4. ~ ~br~lr.ra waY 4.5 10 rnll~ thick an~ A a rr~ t~nce in 0.5~ utrat~
~t 30~C o~ 2.a o~ tho bipol~r ~nd gu~d A5-all~ly YBa ~e~aur~ wit~ t~e 8~'6 ~br~n~ plncs~d on t~
oat:hodQ 3idO 0~ ~0 ~polar nc~ra~o.
~403~ ~8 ~ ~o~ci~lly ~vail~bl~ anlon exch~ngc 'S ~o~ran~ ~ro~ ~AI Reg,~r~l~ Corporation. the ~embran~
bas ~ knoss o~ 2 ils and a ra~s'caDc~ ~n 0.~1 ~;odlum sul~te at 30-1:: a~ l-Z ~ r~. The bipola~
~emh~ane hnd gullrd ~ ly ~as ~asurffi ~
4035 on the anodc cid~ o~ ~ bipol~r ~n~.
2~ ~

~1~`~ ''~I~St 250.05 0.710.73 0.7~ 0.17 0.1~ ~.75__U.7S 0.77 0 7 û 2 O.dl9.81 0.~ . 0.
_ _ _0 . 4 0 . ~R G . as O . 90 O. 90 0.~ 0.~20.~ 0.96 0.95 ooo.e o.sc_ G.97 ~.0~ t).
1.O Q.99~.0~ ~.. 05 1.0~
1.2 1.~2~.o~ 1 0~ ~.06 . , _ ~ _ ~ .
.~ c~rrot~t of 1.~ A ~a d~Iuhral~n~ eo ~ut 100 A/~t~, ~5 ~p~roxi~ly 1000 ~J~ 4 curr~nt aoneity ~re~uo~t'y ~t~-_s~ YYi i~ LL ' rJ ~ L u~' J ~EFT . T~l ~161~5~3Y~Y i'. c5 ~Q~;2~ ~

3~gei~t~d ~or oo~cro~al opc~tlons. ~he ~iot~nt~al drop ac:soss ~ne ~pol~r ~s~rane, it ~e~ b~ 4r~rgy re~IuirY~Lent~ ~or acid bas~ qener~tion WQ13. no~
sub~t~nt~ y chan~led by p~ nce or t~e g~u~d 5 ~e~br~n~.
Appa~at~ ei~lar to t~ae o~ l~x~ple ~ w~ UBed tO
~s~ur~ curron~ orr~ic~ncy o~ ar ~D~ano u~ld, ln Exa~pl~ 3 wlt~ and ~ithaut a ~u~rd Jneobrane.
10 T~n apparatuu wz~ codiflod ~o t~at ~parate ~olutiLn could be pu~d to the oo~rt~ntl~ 31 ~nd 92. ~el volt~go proboe ~ r¢Y~d. ~o ~olutlon~ ~srcula~d ~co ~ and ~a wQre ~n NaC~ ne erSlalonoy tor ny~rogon and ~y~oxyl, ton g~r~-t~on W ~ur~l l~y lS porlo~ lly cdlng ~ ~;nown ~aunt Or ~tandard 1~ HC~
to th~ ~Y~r~oir ~upplying coop~rt~nt 8~ ~nd ~al~uring tn~ ti~ or the pH to ~oturn 'co n~utr~ te~
meaouring the oSf ie~ ncy ~ ~ ru~oti4n o~ c-~rr~nt donol'cy ~r~th th~ blpol~ ~a~br~n- alo~e~ thc ~-4~5 20 ~ ne o~ ;EX~plO 3 W~ pla~d on t:ho anod~ Or th~ blpol~r ~n~l thO o~Slcl~ncy wa~ rmlned a~aln.
~ ro~ult~ ~ro ~ bl- 2.

~ ~ ~ .
o ~o o ~ 0.9~0 0 9~ O. gl2 n~
~20 ~
~n~ ~o~ulto cl~rly ~ C ln aO.~ltion to providinq protoction agalr~t ~chanlc~ a~ag~- acro~s 3g tho bip~l~r ~4~brar~H, th~ guard ~Dbran~ 18 a~l- 'eo ~Dprov~ th~ ~at~r ~plitt~n~ ~iSic~cy ot th~ no.

~-Y~ U i~Ji i h' ~ flL _H~J L)t~ I . IU ''ibl~ Y'do'~ Y, ~

~ 2~24~ ~

T~f~ perfor~anca i~prolr~n~n~ swu1d ~ mo~t ~ u} when higher pu~ity ecid a~ o ~ ~coir~bl~.
3.sI~ o netny~ene cn~ Q wa~ plac~ ln ~ 12L
f l~k . ~th ~tlrring, 1000g of poly~ul~on~
co~e~ci~lly ~v~Sl~le Ud~ 18~5 trom A~oc~
~e~or~-lc~ Produc~ rlottA~ 0~1 W41al ~Ade~. ~fl tno ~olyl3ulron~ ~leaollretl, t~ e~raturc ~;a~ ra~
to 40 C ~nd s67g of ~c~tic ~nnyar$ae wa~ acl~G~a cvar a lC p~rlo~ o~ 6 ~ utes. 42lg of g6~ sulrurio acid wae ~dd~d ov~r tho nPxt 30 ~nut~. DUring th~ aG1d ~ddit~on, t~ temparbturR ro~ t~ ~3'C and re~lux oco~rr~. Folla~lrsng t~e a~d~tlqn tho r~a~ctlon was atir~ed ~t ~O'C ~Gr 23.S ~. ~hc ~sac~ion was tho~
5 cool~ to 3~-C ~nd 250 DL o~ ~anol ~oll~wod by lL ct N,~ Q~ylron~ (D~1 v~ ~a~ h~ thy~n~
oi~lorl~ r4nov~a rrO~ t~ r~ctlon Dlrtur~ ~y v~c~um di~ti~l~tion ~ith p~r~ic ~l~dlti<:~n ar D~tP.
~o~utlon con~l~in~ aut 30~ by voight non-~ol~tlle~
~0 includirl~ so~- lrpurltiee. Sho i~purlt~c ~y ~o~rqd ~Y Praclpit~tlon into ~no~ntrate~ NaCl oolu~lon and ro~ o~ltlon o~ asned poly~r, ~u~
tlon 1- not n-co~ or ue- o~ th~ ~eo~
guA~d D~:~n~. ~on ~ax~h~rgo oapac~ty of ~s puri~ d poly~r va~ 6 ~-q~.

A gu~rd ~ n~ W~D pr~p~d ~ e 80~tion ar Ex~pl~ 5 ~3y ~pr~ing tn4 po~.y~r ~olutlorl on a 91 as~
plat~ wlth a ~ cor bl~d~ ~-t ~t ~ nll~- and dr;viny 3e o~ tho sal~r~nt ~n a rorc-d cc~nvu~:tion ovon at 12~C
~ar ~o ~nut~a.
A g~r~ ~o~ran~ propJ~d ~aCOrd1ng to Sx~
w~ pl~ca~ cn eh~ C~ On p~-l-Ct$va ~1d~I o~ a 35 biPO1nr ~Srnnr PreParPd aCCOr~1n9 tO EYn~ Q L a~

~'-r~ r ~ S i hL. . t ~ HL ~ ,IW Ltr ~ . I l i '-ltl J~D ~Y~Y ~, c _ ~ ~'3 '~

. S . 4, 76~ ,161 u~d s~othcd~ r.d to ~li~in~t~
bubbl~ o conductiYc l~y~ ~s us~d. ~h~ potonti41 dro~s o~ the ca~in~tion Y~ ~oasur~ t~ ~o~ir c~arr~ent la~ora~ory electro~ialy~ ppi~a~u~ o~
~gur~ ~ u~ir~g o. ~ ul~t~ at ~o' ~. S~lu~
~ul~a~e ~o~s ~ul~urlc ~cld, ~hlch 1~ highly oos~d~c'cl~e, at th4 ~u~c~ o~ thc J~i~ol~r ~a~r~ne.
Tr.Q ~c~pa~t~en~s wer~ ~ep~rated t~y circul~r ~e;obrane~
havlng ~ 4~ aroa ot ~lC~. q hs outer 1~ co~p~rt~cr~4 o~ th~ ~pp-~utw con~inKl ~odl~ ~ul~ate ~olutlon ~ t~e ~ ct~ c ~15~ and 15~ ~y ~
dlr~t cu~r~ln~ ~as p~u~d throug~ th~ Ja~lonO
~lo c~ r~n~ 2, ~2~ E.p~r~t~ auts~
co~ortment~ (154~ 15~ ~rall t~c lnn~r co;~t~nt~
15 ~$1, S~J. E~s of t~c ~ er ~o~p~en~ ~a~ p~ed srit~ all Ag/A~Cl elec*rod4 '160, ~60~ ~, 1 c~ rro~
st ~ran~ 0), w~ d a~ volt~g~
pro~oc. A ~lr~c: c~rro~ o~ A ~100 A/J1:~ 02 ~F, ~pp~oY~t-~y ~,Voo AJ~ e ~ppllO~I ~cr~
0 gu~Jblpol~ rar~ t~. ~ vo~tags~ acr~f ~
t~t ~ran-e and l~olutlon ~ ~nitored ~a a ~unct~n of til~ vi~ th~ probo-. rh~ potlticl drop ~S 1.2A
~loO A~P~ a~t~r u~trectir.~ th eolt~t~on r-~latan~e 1 4ho~ in ~r~bl~

~..0~ ,, 2 1 . u~
S 1.0 l9 1.02 . .
;~9 ~ Ig _ 3S 3~i 1.0 LYYi ~ Ll'J ~;iul~l~L L H'~l lltl~;. !U 51~ 5~9869 P.3~

2~2~

Witho~t thR gul~ ~rane, ~he potenti~l d~op of the ~pola~ ~e~ran¢ ~e~aur¢d in 1:~8 B~ sol~tie~l w~
Volta. ~U3 for u~e in ~yst~6 ~or~lng etxo~l~
ae~e, n~ #o~l~ication iw no~ d J!or ~ehio l-a~rano to 5 tun~tion a~ An ~ticiont gu~rd ~ran U~in~ ~ ~olution o~ ~3% so~ t~t~
~h~ oa~a~cod 3~ 30- in t~e l~ddle comportm~nt3 o~
oloc~o~al~ c~ll deecri~ed in ~Yanpl~ 3~ a ata~l~
,OOl ~f~in ~hange~ total ~otont$~ rop or 3.6 volts ras ob~erYed ~ wl~r Junnbr~n- pr~par~d ac~or~$ng to ~sc~l~ 1 o~ V. 8. ~" 76~,161. ~e ~o~enti~l drop ~r h~ Jtq ~0 i6ipol~r Dl~b~OnOJI 'Itdtll 2 . 3 ~ol'cs .
~u0, en~ ne~ poe-nto,L ~rop elCrO~lD t.hQ bi~ol~r 15 ~rano was ~ou~ ~.3 vo~t~.

The poten~ial drop neasur~ent~ ot ISX~1~ 8 v~ro r~ t~d, Y~57t that a ~u~rd ~-~brane pr~par~d In 2~ EX~pl~ 6 ~a c~re~!ully ~l~c~ cant to th~l c~t$on lay-r o~ tho ~i~olar ~JIno. ~!he total po~ntial ~rop ~po~n~a~ r~p o~ U~ r- C~ It2~ou~: et~
pc~torlti~l drop ~ ulut~ c~d o~t) ~
~ea~ur~ Wittl the r~ult ~hcvn in Sabl~ 4 And ~lgur~ 7.

S ~ l L ~ ! hlJ D~ l556~986~ P. 33 _ .
2~2l~

_~=~ = i ~ . ~n;~iai ~F
- - : ,., 1 , ,,, .. ;,.. ,.. ;.. . _ _ 0.0 ~i.14 .~ ,,,,4,!1~ -. 4 .
~.5 4.~g Z.O ~.16 LO ¦ 3~0 4.00 . __. .
3.S 4.3 . _ .4~0_ Ac c~n b~ s~n ~p~c~all5r ~ra~ Flgure 7 ) the 1~ ~ot~ntl~l dro~? or an untr~t~ ç~r~ ~rans unc~c3l~l0 ~n~ ~o~< v-ry hlgt~ ~rt-r only ~ ~nut~
~cro~dlngly, gu~/Sir~t ~b~n~ na~on~ w~lcn n~t h~vo ~ aon~uctlve l~.y-r ~r~ not sultab~e rOr a~ ir~
a w~ak aci~ ~y~t~.
2~) ~

n~ ~ ro r~oqo~ troc ths cal~ o d ~an# ~a~ wiped wi~n a p~p r co~ ~oic~ned witn ~ r~ rLn~ ae ~y wl~ or. ~-~e~rAn~ wora tnen ~AA~c~l~ ln ~ho c~ nd thR

pDtor~ti~l ~rop ~a ~e~urod ~ hq ~e~ult~ ~ho~m in Tabls 3, ~nd by ~a ~ol~d lino ln F

2~24~

U - 5 .
:. ; :: .: : : ' . q~dt~l~ Pc~t~ Drcp T ~ ~M ~t. I - ~ ~i~ at ~ ~olt~);
0.~ 4.15 O.S 3.~g 1.0 3.83 1,5 ~.e~
.
2.5 3.79 ~ ~ 3.
10 _ ~ ."

7 . 0 3.7-~
9.0 3.12 11.0 3 ,71 17~0 3.73 . . .
1~ 20. o 3 .72 2~.0 3 ~73 a4.0 I ~Z

po'cont~al drDp ror cna o~ll c~n~ nlng tn- D2rr zo tr~a~o~ ro~brano~ or ~ pr-~ nt ln~vontlon i~ ruch ~or ~tabl~ ~-n thc ~r~latcd gu~d~bipolar ~enbran~
co~in~t~orl ~Co~par~tiv~ ~xa~la ~) an~ ~ho~ ~
~ot-ntl~ hi~:h io only ~ h' ly hlgher th~n tho ~.6 vo~ to~io.l drop ~ oboerv~d Y~ch an 25 uu~ rdod ~lpol-r ~ (~c~plD ~1. Aecord tr~at1n51 ~uar~ ~ranoe Witl~ 1~10 roculte ln Oran h~v~nq qood ~tabillty ~nd lo~ ~ot~ntl~l drop ~n ~Ak ~Cid ~y~t-~ .

LICl) a IUIYI-/L ~ J L~r ~ 0 A eul~on~t~d polyo~lfono ~a~ pr~parod a~o~rd~ng ~o prsco~ro Or ~ca~ple 5 u~ng 2~ ~vr~ a~
anhy:lrL~ ~nd ~uliuric aci~ to gi~e nat~r~ ith ~n 5 i~ln ~xch~e caDac$tY o~ 1.62 e~J~ wo.~ pur~fLed by e~otin~ into 9heQ~ 3n~ otin~ ~,ntt. ~a~cer. A
15'~ wl~lt~on ~ rQP~rc~ y dl~s~vSng ~ n~
g~ls~lnou3 ~at~ri~l w~o prop~o4 b~ ~lns~ L p~;~t o~
th~ mot~anal ~olutioTl to 2 ~ar~ o~ Ya~r . A li~WJl I
lD ~ount oi th~ g~lntinoul~ ~at~rial w ~p~ea~ on t21s al~rf~c~ o~ t~se bi~olor ~r~ nd C~ an~
pr~p~ro~ ~aoore~ng ~co ~xa~l~ 6 w~ pl~ood on ~op. Tb.o pvt~nti~l d~op in Z3~ ~od5.u~ ~cot-t~ ~clu~o~ ~
uro~ ~ abovo ~nd ~a ro~ulSJ aro ~own in Table 6.

0.0 4.
0.5 3.
.
1.0 3.
2.0 3.~2 .~ 3 .
_ ~i5 5~5 ~ 7 _ r I
~1.0 3~89 J.O. O 3 ~ !~0 T~bl~ fi c1-~arly ~ho~J ~ low, o~abl~ tot 30 potenti~l drop. ~hu~ sd _~rnr.~ h~ ng lC91 !5:'0 -~Ji`1 r~LLI_ ~ IG~!iL L~ EP~. TO ~lDl3~D39~6q P.36 ., ~
2~2~

conduotive ~ ayer e~ the i~l~or~t~d polysullono dl~play goo~ con~uct~,ro propere~ n ~ w~k ~c1~ i~y~to~
Cl~aratlv~ a sse~ly ~as ~ n ap~rt and ~ ss rin~ed ~oro1~ghly with water ~e~or~ roa~e~l~ng. r~l~
po~ential ~op ~cros~ t~e coll ~ 8~sr~d a~ a~ove and ~h6l1 r~ult~ ~rQ ~h~n ln T~l- 7, ~low~
10 ~
, ~, ~, . ',', >, ~ , .
, ,, ~ . c s~
0.0 4.;22 . . . ., -.
0.5 4.00 I ~; 1 . ~ 5 . ~i9 ~ _ _ ,,., . , ~ _ Tt~a pot0nt~aL 6ro~ ~o~ur-d ~'chout t~ gal2~tinou~
po1yQ1~ o~y~e bot~c~n t~ ~r~ w~s no~ stab~ ~5 ~hown ln ~ab1~ 6. ~cco~8~y, ~lu--lon o~ a ao ~onduc~v~l lay~r ruch a~ t~ ~ on~td pOly~ulron4 1 c~ltAc~l ~o ~chiovlng ~ 1ow ~nd 4~bl~ tentl-l drop ln o v~ cld ~yda~, ~uch a~ ~odlu~ acut~te .
A gUasd 2~-~;rane ~ pr~p~rod ac¢ordi~g to D~pl-as 6 an~ ~lppd ~n~co 96~ cul~urlc acl~ ror 1 ~lnut-, ~h~n 1eached ~ t~r ~c~ 10 ~lnuee- . ~rhe tr~at4 i ~rd ~n~mbrhn~ c~rs~ully pl~c~d on top ot the ~tic~n 1~yor o~ ~- b~ r ~bran~ co th~t no ~lr ~bble~
w~r~ Preo~nt ~t~fo~n ~ ~r~no~ ot4n'ç~al ~0 drop ~ this gt~rd - Dipol~r ~ran~l o~ebin~ti~n w~
ur~d ln 23~ c-~t~ ao ~ t~ p~rlou-~xanple~t and the re~ t8 ar- ~o~n ln ~ab? ~ , b~low .

~ LL ~ J ~ Y~L _H. ' L;.r ! . I U '_lbl~ l Y. ~ ~

, ~ .
2~2~

, . ~ ~ .i-~f~
. ~ . .,;-.. - .. ,..".. ,,. ~ p $
~1~ ~nutés~, ... (~. ~
.. ~ . _ 3 . ~5 . o 3 . 7 2 .S 3 ~gO
_ . . ~
4.~ 3.
g . 5 ~ .8~
7 . O ~ .~S
il. 5 3 . 7~

'rhuY t~r~Atinq th~ rd ~an~ yilelded a gua~d ~br.~ne wh1ch gaYc a loY and ~ potnnt.al drop.
T)~el r~ult ~ d to b~ dditlon-l sul~on~tlon o~ urfac- ot ~ br~na or ~h~
~ol~n~ ~celost or u~ oulr~r~o scld.

~o sul~onat~d polycul~on~ ~ pared c~ccor~1nsl tL~
thH gRnor~l proc-tur- os' ~pla ~ ~lng elgy o~ poly~er in 170 ~L o~ dlchl~ron~na and ~8g c~ acot~c anhyd~ld~, snd 6~g d ~ulh~ic acld. ~aotlon tl~ ~a~
ext~nd~d ts J,OOb- A~tor caoelnq lnto ~ ~t~ ~d axtr~C~Cing, tnD polym~r na~ a ~ g ~at4r~g ~y mo~r~r.~ o~ ~.o ~ ~r. lon oxcb~ngo capaclty Or 2.71 9.
~. gua~d ~abr~n~ vao ~re~ d ~ ln Ex~yplc 6.
30 Art~r ooollr.g to ro~ t~ra~use a St 3C>].UtrOn S~r ~SI

~J-J~ 5~ LLI~D ~iGNflL _i tW DEPT. TO ~lbl351~3~8t~ ~. a 2 0 ~

oul~on~d pol~r o~ ~x~ple 12 t-ra~ ~p~caa ~nto th~
3uard ~ran~ wlt~ ~ Coctor ~laae w~n 5 m~l cla~rance and th~ co~ted ~e~br~nQ w~6 ~ at l~S-C ~or 5 ~lnut-t~. TA~ gu~d ~na bipol~r _brD.n~s wa~
5 ~ co~ting n~xt tD th~ a~tiDn l~yer Or thQ ~i~¢l~r ~mbr~ in the pr~rious exa~ and ~che po~enti~l drs~p ~aeur-d. F~ults ;~r~ ~ho~m ln T~ble 9 belo~.

~1 t_~

O.~ 3.i~
. . . . ._, 1.0 ~.70 _ . . . _, 2 . 0 3 . 67 3.0 3~7 4.0 3.~
~ O 3.~1 1~GI 3-a2 .
2~ l~. 0 3. 79 .
18.0 ~.19 ~ ~ 3.7~

q~ tot~ potont~ ~Op a~oo~ ~e C-11 we~ low ;~5 ~nd stablo. ~huo, tha culSon~t d ~o~ rone po1yror prov~ tn- r~oc~ ry condu~1v br~go b~ n guard ~nd blpol~r ~ran .
un hy~roxid~ for~ e~- ~n uoak ao~ Ya'cer, 30 on tn~ cation cld- Or ~ bipol~r ~ nen 1~ ic ~r~ L.. ~ r~u~ LLIcA, :~1Ul~ L L~ ~rrI . IU ~ i7bY ~'.~

2~2~ ~

3a ~pllt. ~ biyql2~r ~rar~ i~ 0.~ M Nz~OH h~ a s~et ~o~centi~l drop o~ ~lts at 30- a~ AJllc2~
eur~Qnt den41~ ~he tot~l ~ot~ntil~l drop iRclud~ng t~on W~3 2.7~ ~ol~;~. When ~ rd 3le~0br~n~
5 p~tp~d ~c~ord~ ng to Ex~ltp14 6 W~ pl~lC~ ext to the ca~lvn ~id~ o~ tho bipolar ~ n~ and a cur~nt of 1. 2A ~a~ s~d, th~ pc~t~ l drop ~ra~ un~t~bl~ a~
aho~n in ~le ~Ø

~ n~
0.0 12.35 A. 69 _~

1~.5 5.615 2~S J,.5~
3 .0 4.~2 2P 3.5 ~ .9g 4.0 3 .~'g ~ 4.S 3.61 5 . /~ 3 .63 , !5 . !~ 3 . 1~6 _ . . _ as .5 ~ 7 '~ .5g l~n~ ne~ wero ~op~r~to~, ~nd on~ drap o~ 9.4 '~t~ Y'~l ~S; .~S r~UI I ~LL --~J '~IW~H~ _H8 IJ~r !, i U ~l~ 7 r . .:~;

2~2~

3~
o~ icroyarticulatQ clltlon exc~ ~ng~ res~n p~par~d ~cc:ordlng to Bc~3pl- 6 0~ ~.1.5. 4,76i;,16~ wa8 plaGsil be'c~o~n t~c q~ar~ ~nd bipol~ ei~r~ ~t wau z~tu~ to tl~ c~ cotal po~ntial tr~p ~B
mq~a?~urE~d ~ Ln Cospar~tl~ tx2ulple 1~ e ~cen~lal drop ~r~s ns~t Yery ~ h 2-~ ~ir~t, but atter st~n~lnq i~llio ln t2~ r 1 hour, i~ ~t~ble potentl~l dros~
o~i3~nred ~ n in Ta~l~B 1l ~lOW. Sn ot~e~
ca~n, a ~ta~le poeqntial ~rap ua~ o~erv~ i'chout tha 0 n~-~d. tc~ ~t~ncl ldl~ unlS~r~ dl~ril:ution o~
rhsln ~nsy hl~vq be~n cl~taln~d during th~z ~standlng.

15 -=
O.Q 3.a~ .

1.0 , 2.gl 1.~ ~
2~ ~ . 0 2. 9~_ 2.5 I z.

3.5 3.0~ _ .~ 3.02 ~5 . 4.5 3.01 5.0 ~.95 1~ 0 _ a.o 13.0 _ 3~ 1~.0 2.92 x~plary ~od~nt~ o~ ~o Lnv~urClon hav~
b~n deacrlb~ trtld ~cap~ ;:~ tbo lm~-nt$on $~ tc:
b~ d~t~r~in~ r~ t~lU ~ollol~ln~

Claims

In the claims:

1. An electrodialysis apparatus including at least one unit cell characterized by having:
at least one first membrane having at least one ion selective layer selected from the group consisting of anion selective layers and cation selective layers, and, at least one separate monopolar guard membrane selected from the group consisting of anion selective and cation selective membranes adjacent to and in contact with the first membrane along a layer of the first membrane selective to the same type of ions as the guard membrane.

2. The apparatus as recited in claim 1 further characterized in that the first membrane is a bipolar membrane having a cation selective layer and an anion selective layer.

3. The apparatus according to claims 1 or 2 further characterized by an ionically conductive layer disposed between the guard membrane and the at least one first membrane.

4. The apparatus according to claim 1, 2, or 3 further characterised by:
an ion selective membrane which is selective to anions or cations spaced apart from and serially aligned with the first membrane and the guard membrane, a product compartment therebetween and, an aqueous salt solution feed compartment adjacent to the additional ion selective membrane.

5. The apparatus according to claim 4 further characterized by the additional ion selective membrane is selective to ions of a charge opposite the charge of the ions to which the layer of the first membrane adjacent to the product compartment is selective.

6. The apparatus according to claim 5 further characterized by:
at least one cation selective membrane spaced apart from and serially aligned with the adjacent bipolar membrane and guard membrane, there being a base product compartment between said cation selective membrane and the adjacent membranes;
at least one anion selective membrane spaced apart from and serially aligned with the adjacent bipolar membrane and guard membrane, there being an acid product compartment between said anion selective membrane and the adjacent membranes; and at least a portion of an aqueous salt solution feed compartment serially aligned with each product compartment with the ion selective means therebetween.

7. The apparatus according to claim 3 wherein the ionically conducting layer is hydrophilic or polymeric or formed by wiping the guard membrane with N,N-dimethyl formamide.

8. The apparatus according to claim 3 wherein the ionically conducting layer is a polymeric layer which is a microparticulate ion exchange resin or a sulfonated polysulfone.

9. A method for electrodialytically treating an aqueous stream comprising electrolytes in an electrodialytic apparatus characterized by providing an electrodialysis apparatus according to any of the preceding claims; and treating said aqueous stream.