Patented Mar. 3, 1942)‘ 2,275,211

UNITED STATES PATENT OFFICE _ 2,275,2i1, rRocEss FOR moon) PURIFICATION Oliver M. Urbain and William R. Stenien, Co lumbus, Ohio, assignors to Charles H. Lewis, 4 Harpster, Ohio > " No Drawing. Application January 17, 1938, Serial No. 185,471 5 Claims. ‘ (01. 210-24) This inventidn relates to water softening and tion between polybasic organic acids and metals liquid puri?cation. More speci?cally, it relates having amphoteric properties, or their salts, such to the removal of cations from liquids by a proc reaction yielding the basic salts having cation ex ess of cation or base exchange. ' change properties. These salts may, if desired, Processes of water softening and cation re 5, be converted into other salts possessing similar moval have been known forv a number of years. vproperties by a process of cation exchange, and -Perhaps the most commonly used materials are - all such salts are to be understood as included the zeolites, or alumino-silicates, although many by- the term “basic salts of polybasic organic acids other compounds having base exchange proper and amphoteric metals” as used throughout the ties have. been prepared. Such compounds, 10 speci?cation and claims. however, are not satisfactory for use in waters of The polybasic organic acids employed for the high acidity since they tend to break down and preparation of the preferred exchange com lose their physical structure when brought into pounds are those acids containing two or more contact with acids. _ ' , " . I _ _ theoretical acid hydrogen atoms per molecule. To overcome ‘these di?iculties in the softening 15 Exemplary of such acids are the following: of waters of high acidity, efforts have recently been made to employ hydrogen permutites or Mellitic acid ______. C6(COOH)6 carbonaceous materials having exchangeable hy Mel?lophanic acid ______1-2-3-4-C6H2(CO0H)4 drogen ions. Although’such materials do e?’ect Prehnitic acid ______. 1-2-3-,5-CsH2(COOH)4 water softening and cation removal in acid solu Tetrachlorophthalic acid- CsC14(COOH)2 tions, their capacity for cation exchange is very, ' Naphthalenetetrasulfonic limited, thus making it necessary to employ large acid ______C10H4(SO3H)4 quantities of such materials and resulting in ex _ The metals employed in the preparation of the cessive costs-for softening of. waters of high hy-_ exchange compounds are those having ampho drogen ion concentration. - 25 teric properties such as: Considerable di?iculty has also been experi enced in the regeneration of those hydrogen per Aluminum mutite exchange materials now employed to Tin effect cation exchange in acid mediums. Such Zinc Lead materials appear to be effective only in their 30; ' original 'form, wherein they possess hydrogen Chromium ions, and often have little or no cation exchange Zirconium capacity after attempted regeneration. . Titanium . It is an object of this invention to provide A general equation for the formation of basic vprocesses for water softening and liquid puri? ~ 35..’ salts of polybasic organic acids and amphoteric cation employing-materials which will function . metals may be expressed as follows: satisfactorily in acid mediums. It is a further 1 object to provide materials for base exchange /H M—O—H‘ \having a high capacity for cations. Addition R\ + M(OH),—-o R + XHzO ally, ‘it is an object of this invention to provide a 4'.) H M—O—H process for cation exchange which will permit Polybasic organic . amphotcric basic salt of water acid or its salts metal or ' polybasic organic ‘the regeneration of the materials employed‘with- ‘ its salts acid and ampho1 out appreciable loss. Other objects will be ap teric metal ' parent to those skilled in the art from the fol '_ The foregoingiequation represents the forma lowing description of the processes and mate 45 tion of a desired basic salt of polybasic organic rials employed. {acids and amphoteric metals ' The materials employed .in theprocesses of this invention are the basic salts of polybasic or ' ’M—0—H ganic. acids with metals having amphoteric prop (represented by the formula R / I ) ertie's. These materials are prepared by the reac \M—O—H 2 2,275,211 through the reaction of a polybasic organic acid ' equation for the preparation of such a salt reads with an amphoteric metal. It will be observed as follows: that the resulting salt is basic since it possesses replaceable cations attached to the organic mole cules through the amphoteric metal and oxygen. The acidic hydrogen of the polybasic organic acid C O O has combined with one or ,more, but not with C O 0 . all, of the anion groups of the amphoteric metal compound. The remaining anion groups of the amphoteric metal compound provide the replace 10 ' 000 able cation which is utilized according to this in C 0 0 vention to e?ect cation exchange. ' Exemplary of one reaction which may be ef iected to produce the cation exchange materials C O O I 15 Basic aluminum mellitate sodium or this invention is the following equation show chloride ing the reaction between mellitic acid and alu C 0 O minum hydroxide: A1—0--Na coon C O O 20 -

C. %coon/c oon Cs /c 0 0\Al-- O —N B + 3 H 0 l x0001: x0 0 0/ 26' ' C O O \coonC O OH Al——0—Na Mellitic acid aluminum hydroxide ' 000/ ' sodium salt of basic hydro ' aluminum meliitate chloric acid 3° It will thus be observed that the materials em ployed in this process conform in general to the following structural formula or modifications ‘Cu _ Al-O-H + BRIO thereof: C00 xcoo/coo 35 \m-o-n s1--o-H coo/ 000 Basic aluminum water /coo ‘ 40 m/ \Al_ 0 ' n I ’ mellitsto The preparation of the sodium salt or stannic prehnitate through the reaction of sodium \coo/' coo prehnitate with stannic chloride is represented by lu-o-n the following equation: 45 - C00 ' 0 0 ONa It will be understood that this formula is illus C 0 ONa trative only; that the organic acid radical portion C‘H: + 2SllCl| + ‘H30 —-—0 may be any one of many organic acids with poly C 0 0Na basic acidic components, such as carboxylic, sul 0 O ONa Iuric, and other radicals; that the metals may Sodium preh¢ stannic water so be any metals having amphoteric properties; and . nitste chloride 0 O 0 CM: that the compounds may have exchangeable hy \ / drcgen or metallic cations. It will also be under /s§ stood thatthe number 01' groupings as shown in ca 2000 0N8 + 8H0! 55 the above exemplary structural formula may be '\c o o om widely varied. \ / The essential characteristics of such materials are (1) their‘formation through the reaction of C 0 0/s§ ONa sodium salt oi’ hydro polybasic organic acids or their salts on metals stannic prehni- chloric having amphoteric properties,- or theirsalts, and tote acid (2) their available replaceable cation,‘ either con These and other materials obtained by meth stitutive or sorbed, resulting from the incomplete ods similar to those represented by these equa- reaction or some, but not all, of the amphoteric (tions were found to possess a high capacity for anion groups with the cations of the organic base exchange, were quite stable in acid solu-_ 65 acids or salts. This latter characteristic is spe tion, and could be quickly and satisfactorily re ci?cally recited in the claims by the use of the generated without appreciable Lloss. term "basic" in referring to the exchange salts. The exchange materials containing replaceable The reaction products are solid materials having hydrogen may be converted into their salts by a solubility of less than 0.03 gram per 100 cc. treatment with solutions containing cations 70 of water at 20'C. which will replace the hydrogen ions. For ex The base exchange materials thus prepared are ample, the sodium'salt of basic aluminum mel- » employed in water softening or liquid puri?ca 'litate may be prepared by treating the material tion in conventional methods. They may be obtained in the ?rst oi the above equations with utilisedincontact?ltersandadaptedtouse> a concentrated solution or sodium chloride. The In in the ?lter'bed type of water softening ap 2,275,211 '3 paratus. Or-such materials may be added din from water may be illustrated by the ‘following rectlyv to the liquid with agitation, after which equation: the converted exchange compounds are separated coo , andremoved from the softened water or puri?ed Al~0 liquids. 5 Reactions of the basic salts of polybasic organic 000 \\cu acids and amphoteric metals with hardness, - 000 forming cations of water or with other cations which one may be desirous of removing from c. \Al——0/ +2110] —» a solution are given in the following equations. 10 For purposes of illustration, the exchange mate XCOQ/coo rial is shown as containing only a few active groups, but it should be understood that such materials may contain a plurality of such active COO groups. ‘ 15 Calcium salt‘ of basic _ hydro aluminum mellitate , chloricacid O O 0 ‘ COO /Al—O-H " C 0 0 0'00 /Al—-O—H 20 %o 0 0\ //c00 ’ \ Ce ' ‘ Al-O-H + CaCl: * Cl . Al-O-H-l-CaCh \_ C 0 0 / C O 0 xcoo/COO Al-O-H 25 Al—0—-H C 0 0 C O 0 Basic aluminum calcium basic aluminum calcium mellitate chloride mellitate chloride 0 O O Exemplary of the regeneration of the sodium 30' salt of stannic prehnitate after it has become /Al—0 exhausted in the removal of magnesium cations C 0 0 \ from water, through the use of an acid, there /c0o/ '\ / Ca‘ is given the following equation: 0¢\ /Al—0 +2HCl 35 \ G 0 O C O 0

C 0 0 /A1—O—H calcium salt of hydro basic aluminum chlorlc Magnesium salt of mellitate acid stannic prehnitate ' 0 0 0 O-Na \ / 0-H /sn\ 45 60H /C0O 0—-Na + 2M 01 2\.o o o 0—Na a g ' ——> \ '/ /s“\ C O O 0—N a . Sodium salt of stannic magnesium 50 prehnitate chloride “ ba'sic stannic prehnitate magnesium nitra to C0 0\ . /O\ Or an exhausted basic stannic prehnitate ex /Sn\ /Mg I change material may be regenerated through 55 treatment with an alkali in accordance with the cm. /0 0 O 0 + ma C] following equation: ‘ ’\c00\ /0\ ' /sn\ /Mg 0 0 0 v0 magnesium salt of stannic sodium prehnitate. chloride After the exchange materials have become ex hausted, they may be regenerated by treating with solutions of acids, salts, or bases. A pre Magnesium salt of ferred process of regeneration involves the treat 65 stannic prclmitate hydroxidesodium I ing of the exhausted exchange materials with O-Na solutions containing from_2% to 8% of mineral acids. The regenerating solutions may be ?owed ‘ through the exchange material in the conven O-Na tional regeneration process, or the exhausted ex-. ' change material may be treated with the regen crating liquid in vats or containers. The regeneration of a basic salt of_ a -poly \sodium salt of basic _ magnesium '‘ basic organic acid and an amphoteric metal stannic prehnitata , Lydroxidc which has been used to remove calcium ions 75 The cations removed from theluliquid being 4 2,275,211 treated will, of course, be found in the regen 3. A process for exchanging cations in water crating solutions, and, if recovery is desired, they which comprises contacting the water with a can be removed by conventional methods such solid, water insoluble basic salt of a polybasic as fractional distillation or fractional crystal organic acid and an amphoteric metal charac lization. terized in that it is stable in water and possesses It is tobe expressly understood that the fore high exchange capacity. going description and examples are merely il 4, A process for exchanging cations in liquids lustrative and are not to be considered as limiting which comprises the steps of adding a cation ex this invention beyond the scope of the subjoined change material comprising a solid, water in 10 soluble basic salt ofa polybasic organic acid and claims. , Having thus described our invention, we claim: an amphoteric metal to the liquid, agitating for 1. A process of liquid puri?cation which com a short period, and effecting removal of the con .prises exchanging cations by contacting the verted exchange material. liquid with a solid, water insoluble basic salt 5. A process for exchanging cations in liquids of a polybasic organic acid and an amphoteric which comprises the step of passing the liquid metal, said salt having cation exchanging prop through a ?lter charged with a cation exchange erties. material comprising a solid, water insoluble 2. A process of water puri?cation which com basic salt of a polybasic organic acid and an prises removing hardness-forming cations by amphoteric metal. contacting the water with-a solid, water insol 20, OLIVER M. URBAIN. uble basic salt of a polybasic organic acid and an WILLIAM R. STEMEN. amphoteric metal, said salt having cation ex changing properties.