JP7452796B2 - Method for producing antifreeze agent derived from plant materials - Google Patents

Description

The present invention relates to a method for producing an antifreeze agent derived from plant materials.

BACKGROUND ART Large amounts of inorganic chlorides such as sodium chloride and calcium chloride have been used as antifreeze agents sprayed on roads to prevent roads from freezing in winter. However, it has been pointed out that these antifreeze agents made of inorganic chlorides have secondary effects on the environment. Specifically, these include impacts on water quality in rivers and other areas, impacts on plants and farmland, and metal corrosion of surrounding steel structures and vehicles. Particularly on highways and road bridges, chloride ions from antifreeze agents penetrate into the concrete and destroy the passive film that protects the reinforcing bars, causing not only rust but also cracks in the concrete. This may lead to dangerous conditions such as spalling or spalling of the concrete.

To solve this problem, organic acid-based antifreeze agents such as calcium/magnesium acetate and sodium acetate that avoid chloride ions have been produced. However, since the production cost of conventional organic acid-based antifreeze agents is several times higher than that of inorganic chloride-based antifreeze agents, they can only be used for partial spraying from an economical point of view.

On the other hand, large amounts of wood-based waste such as scattered wood and waste wood are generated as a result of logging and processing of wood, and there are situations in which it is difficult to dispose of this waste. Therefore, attempts have been made to produce antifreeze agents using these wood waste materials and plant materials such as rice straw.

For example, Patent Document 1 proposes a method of producing an antifreeze agent by pulverizing dead pine wood, drying it with hot air, recovering wood vinegar from the wood gas generated by carbonization, and reacting it with calcium. . Further, Patent Document 2 proposes a method of producing an antifreeze agent from an organic acid obtained by subjecting cellulose of dead pine wood to hot water treatment with dilute sulfuric acid, neutralizing it, and then fermenting it. However, these methods also require heat treatment and chemicals, and thus have the problem of increasing the production cost of the antifreeze agent.

Japanese Patent Application Publication No. 2010-155913 JP2011-205934A

Therefore, the purpose of the present invention is to solve the above-mentioned conventional problems and provide a new technology that can produce an organic acid antifreeze agent at low cost using inexpensive plant materials such as wood waste. It is to be.

In order to solve the above-mentioned problems, the method for producing an antifreeze agent derived from plant materials of the present invention is to aerobically decompose refractory organic substances such as lignin contained in plant materials using white rot fungi to reduce the molecular weight. Then, this is anaerobically treated with acid-producing bacteria under alkaline conditions to generate organic acids, and the organic acids contained in the supernatant liquid of this anaerobically treated liquid are concentrated by solvent extraction and used as an antifreeze agent. It is characterized by:

Note that the plant material may be wood waste, rice straw, or the like. Furthermore, the decomposition efficiency can be increased by pretreating the plant material with microwaves or high temperature and high pressure, and then subjecting it to aerobic decomposition using white rot fungi. Moreover, it is preferable that the organic acid contains lower fatty acids such as butyric acid, propionic acid, and acetic acid.

The plant-based antifreeze produced by this method does not contain salt and is mainly composed of organic acids, so it does not cause secondary effects on the environment or rust the reinforcing steel. It will not cause any damage or cause cracks in the concrete.

FIG. 2 is a block diagram showing the manufacturing process of the present invention. It is a graph of the amount of lignin in Examples. It is a graph of the amount of acid-soluble lignin in Examples. It is a graph of the organic acid production amount in anaerobic treatment.

Preferred embodiments of the present invention are shown below.
FIG. 1 is a block diagram showing the manufacturing process of the present invention. In the present invention, plant raw materials are used as raw materials for the antifreeze agent. The type of plant material is not particularly limited, but in addition to wood waste such as scattered wood and waste wood, rice straw and the like can also be used. Not only can these be obtained cheaply or for free, but using wood-based waste can also contribute to the treatment of waste that has been difficult to dispose of. It is preferable that the plant material used as a raw material is pulverized in order to promote the reaction.

Wood contains the main components cellulose, hemicellulose, and persistent lignin. In the present invention, these are decomposed under aerobic conditions using white rot fungi, which is a type of wood-decaying fungi, and are converted into low-molecular-weight polysaccharides. White-rot fungi have the ability to decompose the persistent lignin contained in wood, and are called white-rot fungi because they change the color to white, which is the color of cellulose and hemicellulose that remain after the lignin is decomposed. In the present invention, for example, phanerochaete sordida can be used, but the type of white rot fungus is not limited thereto.

If white-rot fungi are cultured in advance in agar or liquid medium, and the above-mentioned pulverized plant material is added and placed under aerobic conditions at room temperature, the white-rot fungi will aerobically decompose the lignin contained in the plant material. The molecules are reduced and polysaccharides are produced. Nutrient salts such as phosphates and easily decomposable organic substances such as glucose can be added to the medium for culturing white rot fungi to promote the growth of hyphae. It was found that the lignin decomposition time could be shortened by using a liquid medium to which water was added as a medium for aerobic decomposition. The preferred moisture content is about 50 to 90 wt%.

According to the inventor's experiments, about 50 wt% of the lignin in wood was decomposed in two weeks. Although it takes a certain amount of time for lignin to be decomposed by white rot fungi, lignin decomposition can be promoted by pre-treating the crushed plant material using microwaves. In addition, lignin decomposition can be further promoted by subjecting the pulverized wood material to a high temperature and high pressure treatment of, for example, 130° C. and 200 kPa.

Next, the aerobic decomposition solution containing polysaccharides is sent to an anaerobic treatment reactor, and anaerobic treatment is performed using anaerobic bacteria such as acid-producing bacteria to generate organic acids. Acid-producing bacteria are collected from sludge and allowed to acclimate in an anaerobic treatment reactor for several days. As a result of experiments, it was confirmed that the amount of organic acid produced increases in a relatively high pH region, so it is preferable to adjust the pH to an alkaline range of 7.3 to 7.9. When the pH exceeds 8, the amount of organic acid produced tends to decrease.

This anaerobic treatment may be a batch process or a continuous process. In the case of continuous treatment, the anaerobic treatment can be progressed while gradually moving the liquid in the tank of the anaerobic treatment reactor toward the outlet side at low speed using, for example, a spiral stirring means. This anaerobic treatment produces water-soluble organic acids, mainly lower fatty acids such as acetic acid, propionic acid, and acetic acid, in the treatment liquid.

Anaerobic sludge and its supernatant are generated in the anaerobic treatment reactor, and the above-mentioned organic acids are contained in the supernatant. By extracting the supernatant liquid from the anaerobic treatment device, the concentration of the organic acid contained in the liquid in the treatment tank can be concentrated to about 10 times. Note that since anaerobic sludge contains a large amount of anaerobic bacteria such as acid-producing bacteria, it can be reused by sedimentation separation, but if necessary, excess sludge may be removed from the anaerobic treatment reactor.

The supernatant liquid taken out from the anaerobic treatment reactor is a black liquid and has a low concentration of organic acids, so it cannot be sprayed on roads as an antifreeze agent. Therefore, a water-soluble organic acid is further extracted from the supernatant liquid by solvent extraction. As a solvent, for example, tributyl phosphoric acid can be used. As a result, organic acids such as acetic acid, propionic acid, and butyric acid can be further concentrated by about 10 times. Furthermore, since the black pigment is not extracted, the antifreeze agent becomes colorless and can be sprayed directly onto roads.

The antifreeze agent derived from plant materials thus obtained does not contain salt and has an organic acid as its main component. When the freezing effect was confirmed, it was found that by using the antifreeze of the present invention, the ice melting rate at 4°C was 8% faster than that of tap water, and the freezing time was six times longer than that of tap water. confirmed.

As explained above, according to the present invention, organic acids can be produced by subjecting plant materials to aerobic treatment using white-rot bacteria and then anaerobic treatment using acid-producing bacteria, and the plant materials do not contain salt. It is possible to produce anti-freezing agents derived from these materials at low cost. Examples of the present invention are shown below.

A white rot fungus (phanerochaete sordida) provided by the Fungi and Mushroom Genetic Resources Research Center was inoculated into a (potato/dextrose/agar) medium and cultured for 7 days.

Wood powder, which is a mixture of cedar and cypress, was ground using a general-purpose grinder to adjust the particle size to 1 mm or less, placed in an Erlenmeyer flask, and sealed with a breathable lid. This was sterilized by autoclaving (120° C., 30 minutes), and the moisture content of the scattered wood powder was adjusted to 50 wt% with ultrapure water. White rot fungi were punched out from the above medium together with the medium using a cork borer with a diameter of 5 mm, and the resulting disks were inoculated one by one into the center of an Erlenmeyer flask containing scattered wood powder. As a control sample, an Erlenmeyer flask containing only scattered wood powder was prepared. Both were cultured for 2 weeks under aerobic conditions in an incubator at 25°C.

Thereafter, the amount of lignin in the scattered wood flour was measured. The procedure for measuring the amount of lignin is as follows.

First, a cylindrical filter paper containing 1 g of wood powder sample was subjected to Soxhlet extraction for 6 hours using a mixed organic solvent of ethanol and benzene to extract the organic solvent soluble content, and after removing the mixed organic solvent, it was weighed together with the cylindrical filter paper. The amount of organic solvent available was measured.

Approximately 0.3 g of the defatted wood flour from which the organic solvent soluble content had been extracted was combined with 4.5 ml of 72% H ₂ SO ₄ on ice and incubated at 30° C. for 1 hour. Next, the concentration of H ₂ SO ₄ was diluted to 3% with distilled water, heated in an autoclave for 30 minutes, and filtered and suctioned. The residue was weighed to determine the amount of lignin. Further, 2.7 mL of 3% H ₂ SO ₄ was added to 0.3 mL of this filtrate to dilute it 10 times, and the absorbance in the vicinity of 205 to 210 nm was measured using a spectrophotometer to determine the amount of acid-soluble lignin.

The results were as shown in FIGS. 2 and 3. Figure 2 shows the amount of lignin. In the control sample, the amount of lignin did not change after 14 days, but in the sample inoculated with white rot fungi, the amount of lignin decreased significantly, and the decomposition rate was about 50%. On the other hand, the acid-soluble lignin shown in FIG. 3 increased slightly after 14 days. This confirmed that the presence of white-rot fungi decomposed the lignin, which is difficult to decompose and has a high molecular weight, into acid-soluble lignin, which is a low-molecular organic substance.

Next, the anaerobic sludge that had adapted to the anaerobic treatment reactor was collected, and a solution containing aerobically treated scattered wood flour was added to perform anaerobic treatment at room temperature. As a result of measuring the amount of organic acid produced every day, the results shown in FIG. 4 were obtained. This shows that acetic acid, propionic acid, isobutyric acid, and butyric acid were produced.

A supernatant liquid was extracted from this anaerobic treatment reactor and subjected to solvent extraction with tributyl phosphoric acid. The obtained antifreeze is colorless and does not contain salt. When we confirmed the antifreeze effect, as mentioned above, by adding this antifreeze, the ice melting rate at 4℃ was 8% faster than that of tap water, and the freezing time was six times longer than that of tap water. . This confirmed the snow melting effect and antifreeze effect of the antifreeze agent of the present invention.

Claims (4)

Recalcitrant organic substances such as lignin contained in plant materials are decomposed aerobically by white-rot bacteria to reduce molecular weight, and then treated anaerobically by acid-producing bacteria under alkaline conditions to produce organic acids. A method for producing an antifreeze agent derived from plant materials, which comprises concentrating an organic acid contained in a supernatant liquid of an anaerobic treatment liquid by solvent extraction to obtain an antifreeze agent. The method for producing an antifreeze agent derived from a plant material according to claim 1, wherein the plant material is wood waste, rice straw, or the like. 3. The method for producing an antifreeze agent derived from plant materials according to claim 1, wherein the plant materials are pretreated with microwaves or high temperature and high pressure, and then aerobically decomposed by white rot fungi. 4. The method for producing an antifreeze agent derived from plant materials according to any one of claims 1 to 3, wherein the organic acid is mainly a lower fatty acid such as butyric acid, propionic acid, or acetic acid.

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