Patented Apr. 25, 1939 2,155,914 UNITED STATES PATENT OFFICE 2,155,914 PROCESS FOR THE PREPARATION OF A BLEACHING AND STERILIZING AGENT Gerrit van der Lee, Deventer, Netherlands, as signor to Naamlooze Vennootschap industrieele Maatschappij Voorheen Noury & Van Der Laade, Deventer, Netherlands, a company of the Netherlands No Drawing. Application February 23, 1937, Se ris No. 127,296. In the .Netherlands February 28, 1936 11 Claims. (CL 23-190) The present invention relates to a process for to this known process, which is applied to the the preparation of a bleaching and sterilizing sterilization of water, ammonia and chlorine are agent comprising monochloramine (NHaCl) and separately dissolved in water, and subsequently dichloramine (NHCla). The process of the in the water to be treated is mixed with the aqueous 5 vention may be performed in such a manner that solution of ammonia and the aqueous solution of the bleaching and sterilizing agent may be pre chlorine. With this known process of sterilizar pared in the form of an aqueous solution contain ing water there is the difficulty that two sub ing monochloramine and dichloramine in solu stances must be added to or mixed with the water, tion, or the process may be so practiced that the each of which substances must not only be added 19 bleaching and sterilizing agent may be prepared in correct quantity to the Water but also the 10 in the form of a vapor or gas containing mono exact relative proportions of the added substances chloramine and dichloramine. must be maintained for effective sterilization. If, The liquid or gaseous bleaching and sterilizing for example, the incorrect quantity of chlorine is agent prepared according to the process of the added, which may arise because of faulty or ir present invention probably will contain small regular action of the apparatus controlling the 5 quantities of other bleaching and sterilizing sub addition of chlorine, the sterilization of the water stances besides monochloramine and dichlor does not take place in the correct or best man amine. Such other substances may be, for exam ner, although the ammonia, may be added in the ple, chlorine, nitrogen trichloride, ammonium hy required quantity. Similarly, variations in the 20 pochlorite, etc. However, the principal or main additions of ammonia may be prejudicial to the 20 bleaching and sterilizing substances contained sterilization of the water. . As regards reliability, in the bleaching and sterilizing agent or agents, this known process leaves much to be desired. produced according to the present invention, are The process according to the present invention monochloramine and dichloramine. The chem enables the production of a sterilizing agent for 25 ical reaction underlying the process of the pres water which overcomes the above mentioned ob ent invention does not take place with the forma jections. tion of the said chloramines exclusively, but, to Chloramines and nitrogen trichloride prepared Some extent, side reactions also take place. In electrolytically have already been suggested for view of these preceding explanations, it is pre bleaching and sterilizing purposes. According to 30 ferred to refer to the content of active chlorine in a known process, water solutions containing 30 the product produced by the present process in monochloramine or dichloramine, or mixtures of (stead of to its content of chloramines. Such them, can be obtained by the electrolysis of a active chlorine content may be determined by water solution of ammonium chloride, the pH of Well known iodometric methods, and is preferably which has been brought or adjusted to 4.5 to 10. 35 not calculated to chloramines, although mono Now it has appeared in practice that the prepa 35 chloramine and dichloramine are the main ration of the chloramines (mono- and dichlor bleaching and sterilizing substances contained in amines) according to the said electrolytic process the product. takes place with less good yields per unit quan According to the present invention, a bleach tity of electricity than the preparation of nitro 40 ing and sterilizing agent, or a mixture compris gen trichloride by electrolysis. This is to say, 40 ing monochloramine and dichloramine, is pre with a given quantity of electricity, nitrogen tri pared by the interaction of ammonia and nitrogen chloride may be more efficiently prepared elec trichloride or a product containing nitrogen tri trolytically than monochloramine or dichloramine chloride. Also according to the present invention or a mixture of such chloramines. The process 45 a bleaching and sterilizing agent is prepared by of the present invention takes advantage of this reacting nitrogen trichloride upon a derivative more efficient yield of nitrogen trichloride by of ammonia such as urea. The reaction or inter converting the same after production into mono action of these materials may advantageously be chloramine and dichloramine. Nitrogen tri performed at ordinary room temperature, al chloride may be obtained electrolytically accord 50 though the use of temperatures higher than or ing to the process described above by electrolyz 50 dinary atmospheric temperatures is not precluded ing an acidified solution containing ammonium as long as the temperatures employed are not and chlorine ions. prejudicial to obtaining the chloramines. Since for various purposes, such as, for ex It is well known to prepare chloramines by ample, for the treatment of water and sewage, 55 the action of chlorine on ammonia. According monochloramine and dichloramine are more suit 55

2 2,155,94 able than nitrogen trichloride, it was of impor tance to find a process by which the advantages tion. On the other hand, nitrogen trichloride of the electrolytic preparation of nitrogen tri is used for improving the color and the baking chloride were combined with the well known good quality of the flour. Now, according to the pres action of the chloramines (mono- and dichlor ent invention it is possible to carry out both amines) as treating agents. The process of the treatments with a single apparatus for produc present invention solves this problem in that it ing nitrogen trichloride. One only has to con converts the said nitrogen trichloride into the duct the gases from the apparatus for the pro more desirable chloramines. duction of nitrogen trichloride into two pipes, 0. According to the present invention nitrogen One of which goes direct to the mill, i. e., to trichloride may be successfully converted with the place where the flour is to be treated and a very good yield into a bleaching and steriliz the second of which discharges into a vessel ing agent, mainly consisting of chloramines, by where the gases are contacted with a dilute water causing nitrogen trichloride to act on ammonia. solution of ammonia. In this vessel the steriz 15 By the usual methods of preparation, nitrogen ing agent is formed, and it may then be used trichloride is obtained as a gaseous mixture with washingfor the treatmentdepartment. of the Water for the Wheat air, in which the air is present in a great excess in respect to the nitrogen trichloride. If such Methods and directions that have been foll a gas containing nitrogen trichloride is conduct lowed for the treatment of various products with 20 ed into a dilute water solution of ammonia, a chloramines may also be followed in using the bleaching and sterilizing agent is formed accord bleaching and sterilizing agents produced accord ing to the process of the present invention. ing to the invention for similar purposes. The In addition, the process of the present inven quantities of active chlorine that must be ap tion has the advantage that chlorine which might plied for the treatment of water, are, for ex be present in the gas mixture containing nitro ample, as large as with the process according gen trichloride is likewise converted into chlor to which ammonia and chlorine are conducted armines, and thereby such chlorine acquires an into the water separately. increased activity, since in various respects chlo These quantities of active chlorine fluctuate rine is less suitable for treating water than the depending on the composition and the impuri 30 ties of the water, the time of action, etc., and chloramines. If desired, the air coming from must, therefore, be determined for each case the solution of ammonia may again be conducted separately, Also, for the treatment of other into the apparatus for the preparation of nitro products, such as, for example, flour and the gen trichloride. According to this latter pro like, such quantities of the bleaching and steriliz cedure any ammonia carried in the air is not ing agents prepared according to the invention 35 lost but is bound by the acid constituents that are used as correspond with those that are ap are normally present in the electrolyte used for plied for chloramines prepared in a different way. 35 lytically,the preparation of nitrogen trichloride electro The addition of the bleaching agent to the flour is best effected by spraying the liquid, for ex The process according to the invention is, how ample, according to the Humphries process. ever, neither limited to a special method for the electrochemical production of the nitrogen tri the following example will serve to illustrate chloride, nor to electrochemical production gen the process of preparing the bleaching and steril erally. Any suitable electrochemical method of izing agents according to the invention. From the production of nitrogen trichloride may be em foregoing description it will be appreciated that ployed. It is also possible to prepare nitrogen modifications of this following example may be trichloride used in the present invention in the made without departing from the invention. chemical way, for example, by the action of Eacample chlorine or of hypochlorous acid on a solution In a bottle having a wide neck an electrolyte of an ammonium salt. containing per 2000 ccm, of water, 25 g. of am ) Also according to the present invention, the monium chloride, 475 g. of sodium chloride and ammonia may be wholly or partly substituted 25 ccm. of hydrochloric acid, specific gravity 1.19, by urea. If, for example, the gas containing is electrolyzed with a current strength of 1.25 nitrogen trichloride, which is obtained by the amperes. Two graphite rods of 5 mm. diameter electrolysis of an acidified ammonium chloride placed at a distance of 10 mm. from each other solution, is conducted through a water solution are used as electrodes. During the electrolysis of urea of 1% strength, the nitrogen trichloride air is blown through the electrolyte to carry away 55 is bound and the solution of urea acquires the volatile reaction products formed. Accord strongly sterilizing properties. ing to an analysis 0.556 g. of nitrogen trichlo Instead of a water solution of ammonia, an ride and 0.126 g. of chlorine were formed per monia in the form of vapor, preferably in the ampere hour. The gases are conducted into a presence of moisture, may be allowed to act mixture of 5 ccm. of ammonia, specific gravity 60 with nitrogen trichloride, or with air or other 0.91 and 300 ccm. of water. After one ampere gas containing nitrogen trichloride. hour has passed through the electrolyte, the ab The process according to the invention is par sorption liquid contained, according to an iodo 65 ticularly useful in those cases where One can metric titration, 0.469 g. of active chlorine. apply both nitrogen trichloride and chloramines. 65 This is, for example, the case in mills for grind The content of active chlorine in the reaction ing grain. In these mills the water for washing liquid may be further increased by continuing grain, and especially for washing wheat, must the introduction of nitrogen trichloride contain 70 be of good quality in view of the desired keeping ing air. One must, of course, take care that a quality of the grain products. If no water of sufficient concentration of ammonia is present, as 70 good hygienic quality is available, then available otherwise no complete conversion can take place. water of poor or inferior hygienic quality may If required, ammonia is added during the prepa be treated with the bleaching and sterilizing ration, either continuously or periodically. It is 75 agent produced according to the present inven of importance, however, to keep the concentra tion of ammonia as low as possible consistent 75 2,155,914 3 with a good absorption, as otherwise the air flow chloride with gaseous ammonia, said gaseous ni ing through the absorption apparatus may carry trogen trichloride being produced out of con ammonia, with it. Preferably, care is taken that tact with said gaseous ammonia. - the contact of the gas with the ammonia solu 7. Process for preparing a mixture containing tion is as intimate as possible. monochloramine and dichloramine which COm It is also possible to carry out the preparation prises reacting preformed gaseous nitrogen tri of the bleaching and sterilizing agent continu chloride with an aqueous solution of ammonia, ously, for example by making use of an absorp said gaseous nitrogen trichloride being produced tion tower in which the solution of ammonia, en out of contact with said aqueous solution of am monia. 0. 0 ters at the top and from which the bleaching and 8. Process for preparing a mixture containing sterilizing agent is drawn off at the bottom. The monochloramine and dichloramine which com air mixed with nitrogen trichloride accordingly prises preforming nitrogen trichloride and re enters into the absorption tower at the bottom acting such nitrogen trichloride with ammonia to and is carried away at the top after having been form a mixture containing monochloramine and 5 s freed from nitrogen trichloride by the annonia dichloramine, the said nitrogen trichloride being Solution. produced out of contact with said ammonia. claim: 9. Process for preparing a mixture containing 1. Process of preparing a bleaching and steriliz monochloramine and dichloramine which con ing agent which comprises reacting ammonia prises preparing nitrogen trichloride by electro 90 20 with preformed nitrogen trichloride produced out of contact with Said ammonia. lyzing an aqueous solution containing ammonium 2. Process for preparing a bleaching and steril and chloride ions, removing electrolytically izing agent which comprises reacting ammonia formed nitrogen trichloride from said solution, with a material containing preformed nitrogen and, then reacting such nitrogen trichloride with trichloride produced Out of contact with said ammonia to form a mixture containing mono ammonia. chloramine and dichloramine. 3. Process for preparing a mixture of mono 10. Process for preparing a mixture containing monochloramine and dichloramine which com chloramine and dichloramine which comprises prises preparing nitrogen trichloride by electro reacting ammonia with preformed nitrogen tri- . lyzing an aqueous solution of acid reaction con 80 30 chloride produced out of contact with said am taining ammonium and chloride iQns, the acidity monia. of the said solution being greater than the nor 4. Process for preparing monochloramine and mal acidity of Water solutions of ammonium chlo dichloramine which comprises reacting an aque ride, removing electrolytically formed nitrogen ous solution of ammonia with nitrogen trichlo trichloride from said solution and, then reacting 35 ride product out of contact with said aqueous so Such nitrogen trichloride with ammonia. lution of ammonia. 11. Process for producing a bleaching and steri 5. Process for preparing monochloramine and lizing agent which comprises subjecting an aque dichloramine which comprises reacting gaseous ous solution containing ammonium and chloride ammonia with preformed nitrogen trichloride ions to electrolysis to form nitrogen trichloride, 40 40 produced out of contact with said gaseous am collecting such nitrogen trichloride as a product monia. of the said electrolysis and reacting it with am 6. Process for preparing a mixture containing monia to form a chlorine substitution product of monochloramine, and dichloramine which com ammonia. prises reacting preformed gaseous nitrogen tri GERRIT vAN DER LEE. 45 45