JPH0574521B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a treatment agent for leaked sodium hypochlorite. [Prior Art] Sodium hypochlorite is widely used in water treatment for water and sewage systems and as a bleaching agent for paper, pulp, and textiles. In particular, in recent years, disinfection of tap water, for which the use of chlorine agents is required by law, has
The switch from highly toxic chlorine agents to the safer sodium hypochlorite is progressing. However, as usage increases, accidents such as leakage also tend to increase. Sodium hypochlorite is safer and easier to handle than chlorine gas, but it is strongly alkaline and has an oxidizing effect, so there is a risk of damaging skin and clothing if it comes into contact with it. Therefore, in the event of a leak, it must be dealt with promptly. By the way, when dealing with leaked sodium hypochlorite, if you neutralize it by adding acid as it is, chlorine gas will be generated, which is dangerous. Therefore, for example, the Japan Water Works Association's ``Sodium Hypochlorite Handling Guidelines'' requires adding sodium sulfite in advance to decompose sodium hypochlorite, diluting it with a large amount of water, and confirming that no residual chlorine is detected. A method has been adopted to deal with this. This method converts sodium hypochlorite, NaClO, into safe salt through the reducing action of sodium sulfite, Na ₂ SO ₃ , as shown by the following reaction formula. NaClO+Na ₂ SO ₃ →NaCl+ Na ₂ SO ₄ [Problem to be solved by the invention] However, when adding sodium sulfite to a leaked sodium hypochlorite aqueous solution, simply spraying it on the liquid surface will not cause hypochlorous acid Sodium is not decomposed satisfactorily. This is the specific gravity of sodium sulfite (1.561 for heptahydrate salt, 1.561 for anhydrous salt)
2.633) is large, it quickly sinks into the aqueous solution of sodium hypochlorite, and its poor solubility prevents the above reaction from occurring. The present inventors have tried using ultrafine powdered sodium sulfite or porous granules of ultrafine powdered sodium sulfite in order to increase the reactivity. However, it has been found that simply spraying does not cause any reaction, and that it is absolutely necessary to thoroughly stir the aqueous sodium hypochlorite solution after spraying in order to cause a good reaction. If the amount of leaked sodium hypochlorite is small, it is easy to mix the two well by stirring. However, in the case of a large amount of leakage, it is difficult to mix by stirring, and especially in cases where the leakage covers a large area, it is necessary to mix the two evenly by stirring and completely render all the leaked sodium hypochlorite harmless. The problem was that it was almost impossible. Furthermore, in the case of a leak on a slope, unreacted sodium hypochlorite flows away before the reaction between the two is completed, resulting in a problem in that the area of the leak is expanded. Therefore, the present invention was developed by focusing on these conventional problems, and it quickly reacts and renders the solution harmless just by spraying it on an aqueous solution of sodium hypochlorite, and also slows down the flow of the solution. The object of the present invention is to provide a treatment agent for sodium hypochlorite that also inhibits the above-mentioned conventional problems. [Means for Solving the Problems] In order to achieve the above object, the first invention of the present invention mainly consists of a reducing agent for sodium hypochlorite and a gelling agent for an aqueous solution of sodium hypochlorite. The second invention of the present invention mainly consists of a reducing agent for sodium hypochlorite, a gelling agent for an aqueous solution of sodium hypochlorite, and a gel stabilizer comprising a polyvalent metal salt. The gelling agent is a highly water-absorbent gelling agent such as polyvinyl alcohol/polyacrylate-based, starch/polyacrylate-based, cross-linked polyacrylate-based, cross-linked polyvinyl alcohol-based, cross-linked carboxymethyl cellulose-based, or modified polyethylene oxide. Polymers can be used. The present invention will be explained in more detail below. The reducing agent used in the present invention is a reducing agent that reduces sodium hypochlorite to a harmless salt, and may be either an inorganic chemical or an organic chemical. Preferred inorganic chemicals are always sulfites, thiosulfates and nitrites, such as, for example, sodium sulfite, sodium nitrite, sodium thiosulfate, sodium bisulfite. Further, heavy metal salts such as stannous chloride, nickel sulfate, copper sulfate, etc. can also be used. Examples of organic chemicals include urea, its derivatives diphenyl urea, ammonium carbamate,
Thiourea, dimethylthiourea, etc. can be used. In addition, a gelling agent is a highly water-absorbing polymer that has a water-absorbing power of more than 100 times its own weight, and has the property of immediately absorbing water when poured with water, swelling, and gelling the entire water.For example, acrylic acid PVA/polyacrylate-based or starch/polyacrylate-based, such as vinyl alcohol copolymer, or cross-linked polyacrylate-based, cross-linked PVA, or cross-linked carboxymethyl cellulose, such as sodium acrylate polymer. or polyethylene oxide modified products are preferably used. These gelling agents may be used alone or in combination. In addition, the gel stabilizer is a polyvalent metal salt that has the function of stabilizing the gelled state formed by the superabsorbent polymer absorbing water, such as calcium hydroxide, magnesium hydroxide, magnesium carbonate, etc.
Calcium carbonate, calcium chloride, magnesium chloride, aluminum hydroxide, etc. can be used particularly effectively. These gel stabilizers are not only one type, but also
Two types can be mixed and used. The treatment agent for sodium hypochlorite of the present invention is a mixture mainly consisting of these reducing agents and a gelling agent made of a superabsorbent polymer. Alternatively, it is a mixture mainly consisting of these reducing agents, a gelling agent made of a super absorbent polymer, and a gel stabilizer made of a polyvalent metal salt. The ratio of gelling agent to reducing agent in the mixture is 10
~80% by weight. If it is less than 10%, it will not gel, while if it is more than 80%, it will be wasted. The ratio of gel stabilizer to reducing agent should be in the range 10-40% by weight. If it is less than 10%, no gel stabilizing effect can be obtained. On the other hand, if it exceeds 40%, it becomes excessive and gel aggregation progresses too rapidly, preventing the reducing action of the reducing agent from reducing sodium hypochlorite. The treatment agent for sodium hypochlorite of the present invention is composed of the above-mentioned reducing agent and gelling agent, or reducing agent, gelling agent, and gel stabilizer, and further includes other auxiliary agents for reducing action and gelling. This also includes substances added to the extent that they do not inhibit the action. In other words, if powdered inorganic compounds such as white carbon, activated alumina, zeolite, diatomaceous earth, and acid clay are added as auxiliaries, the deterioration and caking of superabsorbent polymers due to moisture absorption can be prevented, and long-term shelf life can be improved. It is effective for improving These auxiliary agents also function as free-flowing agents, so for example, the above-mentioned sodium hypochlorite treatment agent to which these auxiliary agents have been added can be filled in the container of a pressurized gas emission device using carbon dioxide gas. For example, in the event of a leakage accident, it is possible to effectively radiate almost the entire amount and respond quickly. When the sodium hypochlorite treatment agent of the present invention is sprayed on an aqueous solution of sodium hypochlorite, the gelling agent rapidly absorbs water and swells. And prevent the free flow of the leaked sodium hypochlorite aqueous solution. Therefore, it is possible to prevent the dangerous aqueous sodium hypochlorite solution from spreading over a wide area. At the same time, this gelling agent also prevents the mixed reducing agent particles from settling to the bottom of the aqueous sodium hypochlorite solution and floats them to the surface of the gel to catalyze the reaction with sodium hypochlorite. be promoted. As a result, the reduction reaction can proceed rapidly even without stirring the sodium hypochlorite aqueous solution. However, in the absence of a gel stabilizer, sodium hypochlorite and the reducing agent react with each other, and the polymer chain of the gelling agent is broken and decomposed, and once inside the three-dimensional structure of the superabsorbent polymer, It releases the water trapped in it. Therefore, the stabilization time for gelation is extremely short, for example within several minutes, and fluidization occurs again. Therefore, if a gel stabilizer is not mixed, it is necessary to quickly dilute leaked sodium hypochlorite with a large amount of water after decomposition treatment. When a gel stabilizer is mixed, multivalent ions in the stabilizer form a cross-linked structure with the superabsorbent polymer, thereby enhancing the stability of the gel. As a result, the gelled state is maintained for several hours to several tens of hours or more, and after the reduction treatment, it can be processed with a scoop, making subsequent handling extremely easy. [Examples] The present invention will be explained below using Examples. Examples 1 to 4 A reducing agent and a gelling agent were mixed in the composition shown in Table 1, SiO ₂ was added as an auxiliary agent to prevent caking, and the mixture was filled into a sprayer, and the mixture was filled with sodium hypochlorite. Injected into aqueous solution. The sprayer nozzle has a radiation distance of 1
A modified jet with a low speed of about 2 meters was used so that the treatment agent could make a soft landing on the sodium hypochlorite liquid surface. Industrial grade sodium hypochlorite with 12% or more of available chlorine was used and placed in a 500 x 500 x 200H container. The results are shown in Table-1. In the table, A-
Na is sodium acrylate polymer, A/VA
represents an acrylic acid vinyl alcohol copolymer. Note that residual chlorine was determined by the orthotolidine method. Comparative Examples 1-2 Using only a reducing agent, it was sprayed into a sodium hypochlorite aqueous solution containing 12% available chlorine using a sprayer as in the example. Comparative Example 1 was simply sprayed. In Comparative Example 2, the liquid was stirred after spraying. From the above results, the reduction reaction did not proceed by simply spraying only the reducing agent, and stirring of the liquid was an essential condition. On the other hand, in the case of the example in which the reducing agent was mixed with a gelling agent and a gel stabilizer, the reduction reaction of sodium hypochlorite proceeded rapidly just by spraying it, and it remained in the solution after treatment. No chlorine was detected. In addition, gelation occurred extremely quickly, and post-treatment procedures were also extremely easy.

〔Effect of the invention〕

As explained above, according to the present invention, the contact between sodium hypochlorite and the reducing agent is significantly promoted by the gelling agent. All you have to do is spray the leaked aqueous solution of sodium hypochlorite, and there is no need to stir it at all. Furthermore, when a gel stabilizer is mixed, the liquid to be treated maintains a gel state for a long period of time, so that leaked liquid can be prevented from spreading, and handling such as transportation after treatment can be made extremely easy.

Claims (1)

[Scope of Claims] 1. A treatment agent for sodium hypochlorite, which comprises mainly a reducing agent for sodium hypochlorite and a gelling agent for an aqueous solution of sodium hypochlorite. 2. A treatment agent for sodium hypochlorite, which comprises mainly a reducing agent for sodium hypochlorite, a gelling agent for an aqueous solution of sodium hypochlorite, and a gel stabilizer consisting of a polyvalent metal salt. 3 The gelling agent is polyvinyl alcohol/polyacrylate type, starch/polyacrylate type,
The treatment agent for sodium hypochlorite according to claim 1 or 2, which is a highly water-absorbing polymer such as a cross-linked polyacrylate-based, cross-linked polyvinyl alcohol-based, cross-linked carboxymethyl cellulose-based, or modified polyethylene oxide.