CA1129752A - Disinfectant chlorinated cyanurate containing compositions and method of use - Google Patents

Abstract

DISINFECTANT CHLORINATED CYANURATE CONTAINING
COMPOSITIONS AND METHOD OF USE

Abstract of the Disclosure A disinfectant composition for use in water conditioning systems is produced by dry mixing sodium chloride and a chlorinated cyanurate and pelletizing the mixture. The composition releases free chlorine to disinfect brine solutions used in regenerating domestic water conditioning ion exchange columns and prevents bacterial contamination of such columns.

Description

~1~975;~
BFN 6770 ~1~

DISINFECTANT CHLOR~N~TE~ CyA~u~ATE CONTA~ G
_ COMPOSITIONS ~ND METHOD O~ USE

........ .... .... .... ...
Back round o~ 't~e Invention g ~
Thi~ lnvention relates ~o disinfectant compositions, and more particularly to a pelletized disinfectan~ salt composition for use in water softening systems.
Dls~nfection of domestic water supplies in the United States b~ chlorination has been practiced since the late 1800's Early methods utilized chlorinated lime, ~odium and calcium hypochlorite, or chlorine gas added to water systems at a central location. The use of chIorinated cyanurates as a convenient source of available chlorine for bleaching and disinfectant purposes has also been ~opular for several years.
These organic compounds, genexally classified as chloxamines, contain chloxine bearing nitrogen atoms located ketween a pair of carbonyl (C=O) groups and have been found to exhibit good stability as well as bactexicidal properties in water.
In recent years, the increasing numbers of backyaxd swimming pools has created a need for disinfecting compositions which are added directly to the ~ater b~ the individual consumer. Both hypoc~lorite and chlorinated cyanurate compounds have found use in swimming pools as disinfectants~ See, for example, Hilton, "The Chlorinated Cyanurates"~
'SWi~n~i'ng Pool Age, Nov. 1961~
In European countries, there has been a recognition of the problem of possible bacterial growth in brine solutions used to regenerate water conditioning sx~stems, Bacterial growth in such solutions could contamlnate domestic drinking water supplies if b~cteria remained in the ion exchange resin column ~ter ~ xegeneration c~cle Efforts have '~

BFN 6770 ~-been made in Europe to combat this problem by txeating the ion exchange columns after each regeneration cycle with chemicals or in some cases with silver impregnated resins that have been dispersed into such columns.
However, chloramine compounds, one of the chemicals u$ed~ do not react rapidly and require contact times o~ at leas~ two hours to disinfect effectiv~ely a water $uppl~, See, W. Hardenbergh, Water Supply and Purification 413 ~1952). Such long contact times are impractical for domestic water conditioning systems since the ion exchange resin would be unavailable to perform its softening function for extended time periods.
Use of silver impregnated ion exchange resins in the xe$in column likewise is impractical because of the high cost of such resins and the ineffectiveness of silver compounds in disinfecting water supplies. Id. at 416.
Accordingly, the need exists in the field o~ domestic water conditioning for a means to disinfect e~ectively brine solutions used for regeneration of ion exchange resins thus avoiding contamination of such ~esins and resulting in a minimum of time for which the ~ater conditioning unit is unavailable to perform its softening function.

. .
Su-mmary of the Invention In accordance with the present invention, a di~infectant composition is compounded with sodium Chloride~ and the mixture is formed into pellets.
The disinfectant pellets can then be added to the brine storage tank o a conventional domestic water 3~ conditioning system. As brine solution is formed at the bottom of the storage tank by dissolving the pellets in water, chlorine disinfectant is released fxom the pellets to control effectively any bacterial growth in the solution. There is, therefore, no dan~er of bacterial contamination of the ion exchange column during regeneration with such brine solutions.

:~L2~7~iZ
BFN 6770 ~3-~ the dlsinfectant agentr yaxiou~
chloramlne compounds can ~e utilized. Des~rable properties ~or such compounds include high available chlorine content, solid cr~stalline orm for ease of pelletizing, rapid solubility in water, stability in dry formulation, nontoxlc to humans at low cancentrations, and no calcium ion ccntamination.
It h~s ~een found that chlorinated cyanurate compounds such as potassium dichloroisocyanurate ~l-potassium, 3,5~dichloro-s-triazine-2,4,6-t~ione) and sodium dichloroisocyanurate (l-sodium9 3,5-dichloro-s-triazine-

2~4~6-trlone) are particularly useful and possess all of the above properties.
The disinfectant pellets are for~ed by mixing ~ small, predetermined amount of a dry powdered cyanurate com~ound with fine grain crystalline salt (i.e., soaium chloride or other regenerant salt). The mixture may then be compressed into pellets using a conventional pill press. It has been found that by using a xatio in the range of 6.5 x 10 3 grams of potassium dichloroisocyanurate to about one gram of salt, sufficient residual chlorine will be released into the brine solution to insure bactericidal effectiveness oyer extended periods of time.
~ccordir.glv, it is an object of this invention to provide an inexpensive, convenient to use, and effective means of disinfecting brine solutions in domestic water conditioning svstems and thereby avcid contamination of the ion exchange column during regeneration, This and other objects and advan~ages of the invention Will become apparent from the following description and appended claims.

~L25975;2 BFN 6770 -~

Descri~tion of the Preferred ~m~odimen~s Chlorinated cyanurates have been used safely as sources of available chlorine for bleaching and disinfectant purposes for several years. They are, therefore/ known to be effective in controlling the growth of bacteria Their use in swimming pools as a source of chlorine has also shown them to present no toxicological problems to humans. The preferred chlorinated cyanurates for use in this invention are lQ potassium dichloroisocyanurate (l-potassium~3,5-dichloro-s-triazine-2, 4, 6-trione) and sodium dichloroisocyanurate (l-sodium-3, 5-dichloro-s-triazine-2, 4, 6-trione). They are availa~le from Monsanto Chemical Company, St. Louis, Missouri, under the trademarks ACL-59 and ACL-60, respectively. It has been found that these compounds exhibit the physical properties required for use as disinfectants in brine stoxage tanks. The compounds have a high percentage of available chlorine, they have a solid crystalline form and rapidly dissolve in water, and they are stable when dry mixed with sodium chloride.
The chIorinated cyanurates can be mixed easily with fine grain sodium chloride and then pelletized by using a conventional pellet mill or pill press. It was found that moderate pressures (up to 50,000 psi~ were sufficient to ~rm the granular m1xture into compact pellets. The size and shape of the pellets are not critical, with the major consideration being the ease of handling of the pellets. Pellets 3a having diameters of from 1/4" to 1/2" and having generally spherical or flattened pill shapes are preferred.
It has been found that the addition of as little as 1 to 3 ppm tmg/ll of dichloroisocyanurate compound produces a very high initial kill rate of bacteria which greatly reduced the bacteria even after 96 hours. Addition of 3 ppm and above of dichloro-isocyanurate to a water system should provide both a ~ 2~33752 BFN ~77a -5-high initial kill rate as well as sufficient residualchlorine to maintain an essentiall~ bacteria-free environment.
}Iowever, to establish the effectiveness of such known disinfectants in term of the present invention, a series of tests were run to check the effect of brine solution and moist air on the residual levels of chlorine produced with the disinfectant chemicals and the ability of the pelletized composition to maintain a sufficient level of residual chlorine in a brine storage tank environment~ The results were as reported in the ~ollowing examples.

EXample I
The ef~ects of brine solution and humidity on residual chlorine produced by cyanurate compounds ~5 were tested. Deionized water was saturated with sodium chloride at room temperature. Potassium dichloro-isocyanurate was then added to the saturated solution at a ratio of 100 mg cyanurate to one liter of solution. The starch-iodide method was used to determine residual chlorine content. Samples were taken and tested at several intervals. The results are xeported in Table I below~

.. ....
''Tab'le I
Rasidual 'Chlorine tm~ '~ime ' 446 0 (at mixing~
465 30 minutes 436 1 hour 195 815 days The results show that the maximum level of residual chlorine occurred shortly after mixing and that the level then dropped ovex a period of several days.

:
;2 BFN 6770 ~6- , significant level of residual chlorine remained in ~he test solution even after 8.5 days, indicating that brine has no drastic effect on the residual chlorir~e level produced by cyanurate compounds.
Fresh, dry potassium dichloroisocyanurate was tested against cyanurate which'had been exposed to the ambient air for three days to determine if moisture in the air significantly affected the stability or ability of the compound to release free chlorine. To test this~
2000 mg/1 of potassium dichloroisocyanurate ~both fresh and a~ed 3 daysl was added to one liter of deionized water.
Samples were taken at 30 minute intervals. The results are reported in Table II below.
... ... ..
' Tab'l'e 'II
Residual Chlorine Time Fresh Aged (mln.) (m~/l) ' tmg/l) gog 896 ~0 866 905 The results indicate that the cyanurate-compound remains stable upon exposure to the ambient atmosphere and that moisture in the air has no significant effect on the ability of the compound to release free chlorine in solution.

E~ le II
The tests in this example were designed to determine the disinfection potential o~ salt and potassium dichloroisocyanurate pellets in a simulated brine storage tank environment. The experiment was carried out over a three-month period to insure that the pellets would not be degraded over a reasonable period of time such as would be required for a given BFN 6770 ~7- ~29752 charge of pellets to be used by a domestic water conditioning system.
Fine grain crystalline sodium chloride and powdered potassium dichloroisocyanurate were mixed together in a ratio of about 6.5 x 10 3 grams of cyanurate to one gram of salt. The mixture was fed to a three-eighths inch diameter pill press where it was formed into pellets.
Two 4.4 cm diameter ylass columns were constructed and sealed at the bottom with one hole ~ubber stoppers. Tubing from the stoppers was clamped shut ~hen water was not being added to or removed from the column. Disinfectant pellets we~e added to the columns maintaininy a ratio of 36" of pellets for every 6" to 8" of water. Brine solution ~as removed every third day for testing of the level of residual chlorine by the starch iodide method. Fresh deionized water ~as introduced to replace the brine. The tops of the column5 were loosely covered to keep out contaminants 2Q but permit air circulation. The results are reported in Tables III and IV below.

Table III
Water Column Inches of No. of Height No. Pellet's 'Pellets ' (in.) 1 30 690 5.84 2 23 530 4.50 ~Z~75~
BFN 6770 -8~

~able IV
, :
~esiduaL Chlorine ... ............ ............
Column #l Column # 2 Ti~e Elapsed_ . -mg~l mg~l days 53880.0 3150 3 85~.0 990 6 1870.0 801 970.0 801 . 12 100.0 826 lS
10 800.0 . 740 40 25.3 2~7 46 ~:
14.4 1280 ~9 400.0 485 52 15 885.0 362 55 312,0 668 59 550.0 20 62 296.0 366 65 ~ .
866.0 1188 68 2Q 5~4.0 1184 72 322,0 868 75 595.0 616 78 154.0 275 81 1120.0 482 8~
25 380.0 790 87 121,0 1015 ~0 1036.0 504 ~3 Ayera~e 658.0 my~1 777 mg/l As can be seen from Table IV, there was 30 substantial variation in the measured residual chIorine levels. This can be explained partly by the visually observed phenomenon of hanging up of the pellets in the small diameter columns above the water level. This BFN 6770 ~9~ ~ ~297Sz problem would not be present in a large diameter brine storage tank such as those used in domestic water conditioning systems. Additionally, when fresh water was added to the colum~ the pellets under water would dissolve and new pellets would slide down the column to replace them. Water would be displaced upwardly, wetting even more pellets and causing high residual chlorine levels for a short tîme.
However, even after g3 days, the pellets in both columns were producing significant residual chlorine levels. The dry pellets remaining in the columns had not degraded, and the long-term exposure to ambient air and humidity had not adversely affected their disinfecting potential.
While the compositions and methods herein descxibed constitute preferred embodiments of the in~ention, it is to be understood that the invention is not limited to these precise compositions and methods, and that changes may be made in either without departing from the scope of the invention, which is defined in the appended claims.

Claims (6)

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

1. A disinfectant composition for use in water conditioning systems comprising, a mixture of a bactericidally effective amount of a chlorinated cyanurate and sodium chloride.

2. The composition of Claim 1 in which said mixture has been compressed into pelletized form.

3. The composition of Claim 1 in which said chlorinated cyanurate is potassium dichloroisocyanurate.

4. The composition of Claim 1 in which said chlorinated cyanurate is sodium dichloroisocyanurate.

5. The composition of Claim 2 in which the weight ratio of chlorinated cyanurate to sodium chloride is in the range of 6.5 x 10 3 to 1.

6. A method of disinfecting brine solutions used to regenerate ion exchange resins in a water conditioning system and thereby avoid bacterial contamination of said resins comprising adding the composition of Claim 1 to water in a brine storage tank.