JPS6042207A - Solidifying agent for aqueous solution of sulfuric acid - Google Patents

Abstract

PURPOSE:To solidify efficiently an aqueous soln. of sulfuric acid by adding a polymer of acrylic acid or a copolymer contg. a specific amount of acrylic acid to the aqueous soln. of sulfuric acid and by mixing them. CONSTITUTION:Acrylic acid, a salt thereof acrylamide is homopolymerized to manufacture a polymer, or >=50wt% of said monomer is copolymerized with <=50wt% other copolymerizable monomer to manufacture a copolymer. The copolymerizable monomer is a hydrophilic monomer such as methacrylic acid or itaconic acid or a hydrophobic monomer such as methyl acryl acrylate or styrene. The polymn. is carried out by a conventional method, and the average mol.wt. is adjusted to >=about 50,000. The polymer or copolymer is added to an aqueous soln. of sulfuric acid by about 1-20wt%, and by mixing them, the aqueous soln. of sulfuric acid can be solidified. Sulfuric acid which can be solidified ranges from about 98% concd. sulfuric acid to about 1%dil. sulfuric acid.

Description

[Detailed description of the invention] The present invention relates to an aqueous sulfuric acid solidifying agent.

Dilute sulfuric acid has traditionally been used as the electrolyte in lead-acid batteries, but if this dilute sulfuric acid leaks.

This caused damage to the storage battery itself or surrounding equipment, and also caused health and safety problems. As a measure to prevent such accidents, a solid electrolyte and a method for solidifying dilute sulfuric acid were developed. For the former solid electrolyte, H3MO
12PO40・29H20, H3PW1204G・2
9H20, ZrO(HzPO4)z.nH2O, and strong acid type cation exchange membranes have been reported in gh, but their resistance values are significantly higher than dilute sulfuric acid, making them impractical for use in lead-acid batteries. Inorganic substances have been reported as solidifying agents for dilute sulfuric acid9, and for example, sodium silicate is disclosed in JP-A-48-37642.

The object of the present invention is to provide a solid sulfuric acid stopper consisting of an organic substance, which is achieved by means of an acrylic polymer or copolymer.

The solidifying agent for an aqueous sulfuric acid solution according to the present invention includes acrylic acid,
Polymers or copolymers having a composition containing 50% by weight or more of their salts and/or acrylamide are not limited to sulfuric acid, but also include concentrated sulfuric acid, sulfuric anhydride, fuming sulfuric acid, and arsulfonic acid. .

It is essential that the polymer or copolymer used as solidifying agent according to the invention contains at least 50% by weight of acrylic acid, its salts and/or acrylamide. If the monomer consisting of acrylic acid, its salt and/or acrylamide is less than 50% by weight, the sulfuric acid aqueous solution will not be solidified at all, or even if it is solidified, it will be unstable. In other words, even if the sulfuric acid aqueous solution is solidified when the solidifying agent is mixed with the sulfuric acid aqueous solution, it becomes fluid and phase separation between the 9 polymer and the sulfuric acid aqueous solution occurs over the course of one hour, and the solidified product becomes stable. Bad sex. Acrylic acid, its salts, and acrylamide may each be used alone to form a polymer, or may be mixed in any desired ratio to form a copolymer. In this case, acrylic acid, its salts and/or acrylamide 5
0 wt% or more and 50 wt% of other copolymerizable monomers
A copolymer consisting of the following can be used. The amount of the copolymerizable monomer is appropriately selected within a range that does not interfere with the solidification of sulfuric acid and does not deteriorate the stability of the solidified product.

The copolymerizable monomers may be hydrophilic or hydrophobic. In the case of hydrophobic monomers, the copolymerization rate must not be so high that the resulting copolymer exhibits no solubility in sulfuric acid. One type or a combination of two or more copolymerizable monomers II'i can also be used.

Examples of hydrophilic monomers include methacrylic acid.

Itaconic acid, styrene sulfonic acid and their salts I with N
, N-dimethylaminoethyl (meth)acrylate, N
, N-diethylaminoethyl (meth)acrylate and salts thereof: as well as methacrylamide, N-methylolacrylamide, and the like.

Examples of hydrophobic monomers include acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate, similar methacrylic esters, styrene,
Examples include vinyltoluene, hiniritene chloride, γ-crylonitrile, and the like.

In order to reduce the amount of polymer necessary to solidify the aqueous sulfuric acid solution, a crosslinkable monomer may be copolymerized with the monomer. The crosslinking monomer is preferably used in an amount of 10% by weight or less based on the total monomers.

In particular, it is preferable that the weight be 2 weight or less. Too much crosslinking monomer reduces the degree of swelling of the polymer. Examples of crosslinkable monomers include monomers containing two or more vinyl groups in one molecule and monomers having functional groups that form bonds between or within molecules upon heating or the like. The former includes divinylbenzene, ethylene glycol diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, ethylene glycol dimethacrylate,
Polyethylene glycol dimethacrylate 1/-t.

Examples include trimethylolpropane trimethacrylate.

The latter includes 9 such as N-methylolacrylamide,
Examples include alkoxymethylol acrylamide.

The copolymerization ratio can be arbitrarily changed depending on the purpose.

The weight average molecular weight of the polymer (copolymer Kanakuramet) is preferably 500,000 or more, particularly preferably 1,000,000 or more. If the molecular weight is too small, it will be difficult to solidify the sulfuric acid aqueous solution. In order to reduce the amount of polymer added necessary for solidifying sulfuric acid, it is preferable that the molecular weight is as large as possible.

The above polymers are synthesized by known polymerization methods such as solution polymerization, precipitation polymerization, and reversed-phase suspension polymerization. Solution polymerization, 10 to 5
A water-soluble polymerization initiator is added to a 0% by weight aqueous monomer solution, and polymerization is performed by heating.

Ammonium persulfate is used as a water-soluble polymerization initiator.

Persulfates such as sodium persulfate, potassium perchlorate.

Examples include perchloric acids such as sodium perchlorate, and azo compounds such as 2,2'-azobis(2-amidinopropane) dihydrochloride. The polymerization temperature is adjusted to the decomposition temperature of the polymerization initiator used, but is preferably 50°C to 90°C from the viewpoint of the synthesis operation. The polymerization solution is a viscous liquid, which may be used as is, but it can be dried and dehydrated to form a powder. During precipitation polymerization, the polymerization initiator and monomer are dissolved in alcohol. When the polymerization reaction progresses by heating, the polymer becomes a precipitate. When the precipitate is separated, a powder is obtained.

In reverse-phase suspension polymerization, an emulsifier with a low HLB value and a cellulose derivative are used (0.1 to 1 ON amount relative to the monomer), an organic solvent that is incompatible with water is used as a continuous phase, and an aqueous monomer solution is used as a dispersed phase. In this method, a dispersion liquid is prepared and polymerized as it is to produce polymer beads. This polymerization method also uses a water-soluble polymerization initiator as in solution polymerization. The polymerization temperature must be adjusted to ensure stable polymerization.

The temperature is below the azeotropic temperature of the organic solvent used and water. After the polymerization reaction is completed, the 9 polymer beads are separated by kW.Which polymerization method to use can be decided taking into account the desired polymer, economic efficiency, etc.

In order to solidify the sulfuric acid aqueous solution, the sulfuric acid aqueous solution and the polymer may be mixed. Stirring is preferred for uniform and rapid solidification. The polymer to be added can be added in the form of a single particle, a powder, or an aqueous solution. The amount added is 9
Although it varies depending on the composition and molecular weight of the polymer, it is preferable to use about 1 to 20 layers per sulfuric acid aqueous solution.

The solidifying agent according to the present invention made of the above-mentioned polymer can be applied to a wide range of preparations, from 98% concentrated sulfuric acid to about 1% diluted sulfuric acid. It can also be applied to sulfuric anhydride, fuming sulfuric acid, and chlorosulfonic acid, which exhibit strong oxidizing properties similar to concentrated sulfuric acid, and can be suitably solidified. Therefore, the solidifying agent according to the present invention can be applied not only to sulfuric acid solidifying scales for lead @ batteries, but also to solidifying waste sulfuric acid as a safety measure during storage and disposal in various industries.

Next, the present invention will be explained in detail based on examples.

The present invention is not limited to this.

Example 1 Sodium polyacrylate powder having a weight average molecular weight of about 5 million yen was gradually added little by little to 100 g of concentrated sulfuric acid of 97 J while stirring, and when 89 J was added, 979 J
Concentrated sulfuric acid gelled and lost fluidity.

Example 2 The same operation as in Example 1 was carried out using a copolymer of acrylamide/sodium acrylate (90/l oMM ratio) with a weight average molecular weight of about 5 million, and when 10 g was added, 97% of concentrated sulfuric acid turned into a gel and lost its fluidity.

Example 3 When a 10% aqueous solution of polyacrylamide with a weight average molecular weight of 1 million and 12N sulfuric acid were mixed at a ratio of 1:1,
A gelled, non-flowable 6N sulfuric acid was obtained.

The solidifying agent for a sulfuric acid aqueous solution according to the present invention can efficiently solidify a sulfuric acid aqueous solution.

Claims (1)

[Claims] A solidifying agent for an aqueous sulfuric acid solution, comprising a polymer or copolymer having a composition containing at least 50% by weight of acrylic acid, a salt thereof, and/or acrylamide.