JP2005281242A - Laver acid treatment agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laver acid treatment agent which is rendered a phosphorus-free formulation to prevent an adverse affect on the laver growth environment, and excels in buffer capacity to extremely reduce the variablity of pH, exhibits the acid treatment effect to a maximum, and can surely exterminate miscellaneous algae, bacteria and the like from laver. <P>SOLUTION: Since an organic acid which constitutes mainly the acid treatment agent is mixed with a buffer compound which forms a conjugate base with an acid in a solution and seawater to obtain a state containing a buffer in an acidic solution, the dilution with seawater in the acid treating operation and the variability of pH due to the addition of the acid or a base can be reduced to maintain a necessary acidity for the acid treatment, and thus the acid treatment for laver can be efficiently performed, and there is no need to use a phosphate buffer containing phosphorus which accelerates the eutrophication of seawater, and an adverse affect on the environment surrounding the laver farm can be removed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a nori acid treatment agent for controlling diseases caused by mixed algae and bacteria, etc. mixed in cultured nori seaweed, and in particular, there is very little pH change due to contamination of seawater, and no excessive phosphorus in the ocean. The present invention relates to a nori acid treatment agent that does not cause eutrophication and the deterioration of the nori growth environment resulting therefrom.

  In the cultivation of seaweed, there are problems such as mixed algae and diseases caused by bacteria, etc. As a method for controlling such algae and diseases, we use the difference in resistance to acids between the algae and bacteria and laver. Acid treatment has been commonly used in the past. The acid treatment agent used for this acid treatment is required to have sufficient effect as an acid treatment agent, ease of handling in work, etc. while ensuring the safety of seaweed as a food and the safety of aquaculture workers. There are always improvements. As an example of a laver treatment agent used in recent years, Japanese Patent No. 3296174 discloses an addition of inorganic salts and acids to seawater.

  This conventional seaweed acid treating agent contains seawater, inorganic salts, and acid, has a specific gravity adjusted to 1.03-1.13, and a pH adjusted to 0.5-5.0. . In this seaweed acid treatment agent, compared with the previous treatment agent, the effect of controlling algae and diseases other than seaweed is higher, and the specific gravity is too high and does not damage normal seaweed. The effect obtained with the previous acid treatment agent can be obtained in a shorter time.

  Another laver treatment agent is disclosed in Japanese Patent No. 3369544. This other conventional laver acid treating agent is a solution containing an organic carboxylic acid and ferric chloride, and has a specific gravity of less than 1.03. In this nori acid treatment agent, due to the synergistic effect of organic acid and ferric chloride, it is possible to effectively control noriweed and diseases of nori in a shorter time while having a lower concentration than the previous one, In addition, there is no damage to the laver leaf body, and the work efficiency is improved, and the effect of preventing the deterioration of quality due to fading of the laver by compensating for the lack of nutrient salts in the aquaculture ground is expected.

However, the seawater that forms the growth environment of the cultured nori maintains a pH of about 8 due to its own buffering capacity, and when a large amount of seawater is mixed when using an acid treatment agent for the nori, the pH value increases, that is, acidic. In order to maintain the effect of the acid treatment, a buffer solution composed of a compound such as phosphoric acid or citric acid is generally added to the conventional acid treatment agent in order to maintain the effect of acid treatment. Even if it was mixed, the pH value did not change so much due to the buffering action of the buffer solution.
Japanese Patent No. 3296174 Japanese Patent No. 3369544

  Conventional acid treatment agents are configured as described above, and in many cases, a phosphoric acid compound is included as an acid, buffer solution, or nutrient as the main component of the acid treatment agent. The amount of phosphorus adhering to the seaweed will flow out into the seawater, and the excess phosphorus content compared to the naturally occurring amount will lead to eutrophication of the seawater, that is, a large amount of plankton, and the accompanying nitrogen content in the sea There was a problem that the risk of reducing the growth of seaweed raw algae and discoloration was extremely high.

  In addition, acid treatment of seaweed is best performed with an acid of about pH 2. Conventionally, phosphate buffer or citrate buffer is used together with acid, and it has been devised so that the pH value does not change as much as possible due to its buffer capacity. However, the pH region having the maximum buffering action such as phosphate buffer and citrate buffer is far away from the vicinity of pH 2 where this acid treatment can be effectively performed. There was a problem that the pH suitable for the acid treatment could not be maintained even when the dilution due to seawater contamination did not progress so much.

  The present invention has been made to solve the above-mentioned problems, and as a formulation not containing phosphorus, it prevents adverse effects on the nori growth environment, has excellent buffering capacity, has very little pH change, and exhibits the acid treatment effect to the maximum. It is an object of the present invention to provide a seaweed acid treatment agent that can reliably control miscellaneous algae, bacteria, and the like from seaweed.

  The seaweed acid treating agent according to the present invention is a seaweed acid treating agent containing an organic acid, which does not contain phosphorus and at least a conjugated acid and base compound that forms a buffer solution when mixed with water, and seawater. When mixed with an organic acid, the acidity of the organic acid and the buffering capacity of the buffer components make the pH 1 to 4, and the total specific gravity is less than 1.03.

  As described above, in the present invention, the organic acid that is the main component of the acid treatment agent is mixed with the seawater and the compound that generates a conjugated acid and a base in the solution to obtain a state in which the buffer solution is contained in the acidic solution. Therefore, it is possible to reduce the pH change accompanying the addition of acid and base, including dilution with seawater during acid treatment work, maintain the acidity necessary for acid treatment, and efficiently maintain acidity for seaweed In addition to being able to perform processing operations, it is not necessary to use a phosphate buffer containing phosphorus that promotes eutrophication of seawater, thereby eliminating adverse effects on the environment around the laver farm.

  In addition, the noble acid treating agent according to the present invention is a substance in which each of the conjugated acid and base compounds becomes a buffer solution having a maximum buffering action near pH 2 when mixed with a predetermined amount of seawater as necessary. Is.

  As described above, in the present invention, a compound that forms a buffer solution having a maximum buffering action in the vicinity of pH 2 is used, and a buffer solution component in the acidic region is generated in the acid treatment agent, whereby pH 2 necessary for acid treatment of laver. Has a high buffering capacity in the region, the acid treatment agent can maintain pH around 2 even after dilution with seawater, etc., and can reliably prevent the adhesion of miscellaneous algae and diseases to the laver .

In addition, the noble acid treating agent according to the present invention is one in which the conjugated acid and base compounds are sodium hydrogen sulfate and sodium sulfate, if necessary.
As described above, in the present invention, sodium hydrogen sulfate and sodium sulfate, which are buffers capable of obtaining the maximum buffering action of the buffer solution at pH 1.82, are used, and the maximum buffering ability is exhibited at around pH 2 suitable for acid treatment of seaweed. As a result, even if the acid treatment agent undergoes a change such as dilution with seawater, the acid treatment agent is maintained at a constant value of approximately pH 2, and the acid treatment operation can be carried out efficiently. In addition, the use of highly safe sodium sulfate and sodium hydrogen sulfate, which are commonly used as food additives, etc., does not adversely affect the seaweed and the surrounding environment, and only controls miscellaneous algae and bacteria. Can be executed reliably.

In addition, the noble acid treating agent according to the present invention is one in which the sodium hydrogen sulfate and sodium sulfate are dissolved in seawater from a solid crystalline state and mixed with the organic acid and seawater as necessary.
As described above, in the present invention, sodium hydrogen sulfate and sodium sulfate as a buffering agent are dissolved in seawater in a solid state and mixed with an acid treatment agent to form a buffer component, thereby dissolving sodium hydrogensulfate and sodium sulfate. The minimum required volume can be handled until just before, reducing the work burden on the operator and greatly improving the efficiency of the acid treatment work.

In addition, the noble acid treating agent according to the present invention has a blending molar ratio of sodium hydrogen sulfate and sodium sulfate in the range of 10: 1 to 1:10 as necessary.
Thus, in the present invention, sodium hydrogen sulfate and sodium sulfate having a predetermined blending ratio in advance are mixed with an organic acid and seawater to form an acid treatment agent, whereby a buffer solution component having a maximum buffering capacity near pH 2 is obtained. The contained state can be obtained easily and reliably, and a state capable of exhibiting good acid treatment performance without causing a pH change can be realized without complicated preparation work.

  Hereinafter, the laver acid treating agent according to one embodiment of the present invention will be described. The noble acid treating agent according to the present embodiment is a conjugated acid and base compound that forms a buffer solution having a maximum buffering capacity near pH 2 when mixed with a predetermined amount of seawater, specifically sodium hydrogen sulfate and sulfuric acid. Sodium and seawater are mixed with a predetermined organic acid, and the pH becomes 1 to 4 due to the acidity of the organic acid and the buffer capacity of the buffer solution component, and the total specific gravity is less than 1.03.

  The organic acid is a substance that lowers the pH to a value close to a predetermined value (pH 2) as a main component of the acid treatment agent. Specific examples include citric acid, malic acid, lactic acid, acetic acid, gluconic acid, maleic acid, Examples thereof include organic carboxylic acids containing no phosphorus such as fumaric acid, malonic acid, formic acid, tartaric acid, acrylic acid, crotonic acid, succinic acid, oxalic acid and glutaric acid. The concentration of the organic acid in the acid treatment agent in the state actually used in the acid treatment operation is 0.05 to 0.5%, preferably 0.1 to 0.4%. When citric acid is used as the organic acid, it can be dissolved in seawater or the like from a solid (powder, granule, tablet) state.

  Sodium bisulfate and sodium sulfate as the conjugated acid and base compounds are dissolved in seawater and ionized to form a buffer solution. In addition to being used in a solid (powder, granule, tablet) form in a solvent such as seawater, these may be used in the form of a solution from the beginning and mixed and diluted before use. The blending molar ratio of sodium hydrogen sulfate and sodium sulfate is desirably in the range of about 10: 1 to 1:10, and the pH value of the acid treatment agent can be adjusted to an appropriate range. Table 1 shows the pH value at each blending ratio of 1 molar sodium hydrogen sulfate and sodium sulfate. The concentration of sodium hydrogen sulfate and sodium sulfate in the acid treatment agent actually used in the acid treatment operation is 0.03 to 0.2% for sodium hydrogen sulfate and 0.05 to 0.3% for sodium sulfate. .

  Seawater is used as it is for dilution and dissolution of organic acids and compounds. The solution in which each material is mixed is diluted and adjusted so that the specific gravity of the acid treatment agent actually used in seawater is less than 1.03. The reason why the specific gravity of the acid treatment agent is less than 1.03 is to improve the properties of the seaweed finally obtained as a product. When the specific gravity of the acid treatment agent is 1.03 or more, the acid treatment was performed. The seaweed becomes too soft, leading to defects such as the product being easily broken. On the other hand, when the specific gravity is 1.03 or more, the pH value of the acid treatment agent is excessively lowered, and other adverse effects on the seaweed are increased.

Next, preparation of the nori acid treatment agent according to this embodiment will be described. First, an organic acid, sodium hydrogensulfate, sodium sulfate, and seawater are charged at a predetermined rate into a treatment tank of a predetermined capacity provided on the acid treatment work site such as on a ship, and mixed and stirred as an acidic aqueous solution. An acid treatment agent is obtained. In this case, the amount of seawater mixed may be reduced to obtain a high-concentration stock solution, and this may be further diluted to an appropriate concentration with seawater at an acid-treated site to obtain an acid treatment agent. As the organic acid, sodium hydrogen sulfate, and sodium sulfate, solids can be used, and those previously made into aqueous solutions can also be used.
In the acid treatment agent in this treatment tank, sodium hydrogen sulfate is completely ionized as shown in the following equation.

^{_{NaHSO 4 → Na + + HSO 4}} - ···· (1)
In addition, the hydrogen sulfate ion is partially ionized (however, the symbol for equilibrium is replaced by a double layer of the original top → bottom ←)
HSO ₄ ^- ⇔H ⁺ + SO4 ^2- (2)
And the solution is acidic.

On the other hand, sodium sulfate is completely ionized in the solution as shown below,
Na ₂ SO ₄ → 2Na ⁺ + SO4 ²⁻ (3)
It becomes.
On the other hand, an equilibrium such as the following equation is obtained in the solution.
^{_{H 2 O⇔H + + OH - ··········}} (4)

Here, a large amount of hydrogen sulfate ions and sulfate ions are present in the solution. When an acid is added (H ⁺ increases), H ⁺ reacts with SO4 ²⁻ present in a large amount in the solution and changes to HSO ₄ ⁻ , so that the equilibrium in equation (2) moves to the left, and H ⁺ Decreases and weakens the effect of acid. On the other hand, when a base is added (OH ⁻ increases), H ⁺ is lost due to neutralization, and the equilibrium in equation (4) moves to the left, and the equilibrium in equation (2) is made up to compensate for this decrease in H ^+. As a result, the influence of the base is weakened. Further, even when diluted with water, sodium hydrogen sulfate and sodium sulfate are diluted in the same manner, and the concentration ratio does not change, so there is almost no change in pH.

The acid dissociation equilibrium constant, Ka ₂ (mol / l) of hydrogen sulfate ion (HSO ₄ ⁻ ) is Ka ₂ = 1.50 × 10 ⁻² (pKa ₂ = 1.82), and based on this, pH = 1.82, that is, pH = A buffer solution having a maximum buffer capacity in an acidic region where pKa ₂ is obtained can be obtained.
Thus, the acid treatment agent containing the buffer solution component prepared in the treatment tank has a buffer capacity capable of maintaining the pH at a predetermined value, and using this acid treatment agent, acid treatment work on the laver on the laver net Can be implemented.

Then, the acid treatment operation | work which applies the seaweed acid processing agent which concerns on this embodiment is demonstrated. First, in the state where there is enough prepared acid treatment agent in the treatment tank on the ship, the seaweed net on which the seaweed raw algae is attached is pulled up to the sea so that the ship is positioned below the ship. The seaweed net is raised, placed in a treatment tank on the ship, immersed for several tens of seconds to several minutes, treated with acid, and then removed from the treatment tank and returned to the sea. The worker performs the same operation for each position of the laver net while moving the ship as appropriate. Even if seawater is mixed into the acid treatment agent after the acid treatment work, the pH near 2 optimum for the acid treatment is maintained by the buffer capacity, and the acid treatment can be continued as it is. Even if the pH value changes significantly from the optimum range due to excessive use of the acid treatment agent in the acid treatment operation, only a solid or solution of organic acid and sodium hydrogen sulfate is added to the acid treatment agent at the treatment site. Thus, it is possible to easily return to the original pH value and to restore the buffer capacity.
In addition, the acid treatment work includes a method of spraying the acid treatment agent on the laver net when the laver net is dried, in addition to immersing the laver net in the acid treatment agent.

  Thus, in the laver acid treating agent according to the present embodiment, sodium hydrogen sulfate, sodium sulfate and seawater as a compound that generates a conjugated acid and base in the solution in the organic acid that is the main component of the acid treating agent. To obtain a state in which an acidic solution contains a buffer solution having a maximum buffering action near pH 2, so that the pH change accompanying addition of an acid or a base starts with dilution in seawater during acid treatment Can be made extremely small, can maintain the optimum pH value for acid treatment, can efficiently perform acid treatment work on seaweed, and does not need to use a phosphate buffer containing phosphorus that promotes eutrophication of seawater Eliminate adverse effects on the environment around the seaweed farm.

A plurality of types of nori acid treatment agents according to the present invention are produced by changing the compounding conditions of the organic acid and the compound serving as a buffer, and the evaluation results comparing the pH value of the obtained treatment agent and the degree of influence on the nori are described To do.
(Test 1) A stock solution (first example) in which 15 g of citric acid monohydrate, 11.2 g of sodium sulfate, and 5.2 g of sodium hydrogen sulfate were added to 100 ml of water, and citric acid monohydrate were added. 15 g, 5.6 g of sodium sulfate and 2.6 g of sodium hydrogen sulfate were added respectively (second example), and citric acid monohydrate was not added, 11.2 g of sodium sulfate and sodium hydrogen sulfate were added. A stock solution (third example) added with 5.2 g was prepared. As a first comparative example, a stock solution was prepared by adding 15 g of citric acid monohydrate and 15 g of sodium monophosphate to 100 ml of water as in the case of a conventional acid treatment agent. Diluted solutions were prepared by diluting each of these stock solutions 50 times and 100 times with seawater. The specific gravity of each diluted solution was less than 1.030. Table 2 shows the concentration of each component and the pH value of each solution in each stock solution and diluted solution.

In any of the diluted solutions, the difference in pH due to the difference in the amount of dilution is small, and is kept in the range required as an acid treatment agent. It has been confirmed that the composition of the present invention has a desired pH value that is optimal for acid treatment at the concentration actually used as the acid treatment agent.
(Test 2) A stock solution (fourth example) was prepared by adding 15 g of citric acid monohydrate, 11.2 g of sodium sulfate, and 5.2 g of sodium hydrogensulfate to 100 ml of water. As an example, a stock solution containing 15 g of citric acid monohydrate and 15 g of sodium monophosphate was prepared. And the diluted solution which diluted each undiluted solution 50 times, 100 times, 150 times, and 200 times with seawater was prepared, respectively. The specific gravity of each diluted solution was less than 1.030. Table 3 shows the pH values of each stock solution and diluted solution.

  The composition of the fourth example has a buffering capacity that does not change abruptly even when the concentration is decreased by dilution, and hardly changes even when compared with the phosphate buffer solution of the comparative example. It can be said that the effectiveness as a practical acid treatment agent with little change in acid treatment performance even when diluted with seawater was confirmed.

(Test 3) A stock solution (fifth example) was prepared by adding 15 g of citric acid monohydrate, 11.2 g of sodium sulfate, and 5.2 g of sodium hydrogen sulfate to 100 ml of water. Was added to 50 ml of seawater to obtain a solution having a pH of 1.8. As a third comparative example, a solution of about 0.7 ml of 1N hydrochloric acid was added to 100 ml of water to adjust the pH to 1.8, and as a fourth comparative example, citric acid monohydrate 3.18 g and primary phosphorus were added to 20 ml of seawater. Solutions each having a pH of 2.04 were added by adding 3.27 g of sodium acid. Then, the laver leaf body was immersed in each solution, and the degree of soundness of the laver leaf body, that is, the presence or absence of change in the laver leaf body was examined every 0.5, 1, 5, 10, 15, and 20 minutes. Table 4 shows the rate of change in the laver leaf body for each elapsed time.

海苔葉体は、第４比較例で１５分後に１０％に変化が見られ、２０分後には第５実施例及び第３比較例＜第４比較例の順で変化度合が大きくなっており、硫酸ナトリウムと硫酸水素ナトリウムを用いている第５実施例について、海苔に対する短時間の使用では従来製品以上に海苔への影響が少ないことが確認できた。

The nori leaves are changed to 10% after 15 minutes in the fourth comparative example, and after 20 minutes, the degree of change increases in the order of the fifth example and the third comparative example <the fourth comparative example, About 5th Example using sodium sulfate and sodium hydrogensulfate, it has confirmed that there was little influence on a laver more than a conventional product in the use for a short time with a laver.

(Test 4) In order to obtain a state close to actual use, 440 g of sodium sulfate, 200 g of sodium hydrogensulfate monohydrate, and 578 g of citric acid monohydrate were added to 200 l of seawater (No. 1). Example 6), acid treatment solution (seventh example) in which 224 g of sodium sulfate, 106 g of sodium hydrogen sulfate monohydrate and 288 g of citric acid monohydrate were added, 222 g of sodium sulfate, 98 g of hydrate and 592 g of citric acid monohydrate were added, respectively (Example 8), and 440 g of sodium sulfate, 440 g of sodium hydrogen sulfate, and 578 g of citric acid monohydrate were added. Each acid treatment solution (9th Example) was prepared. Further, as a fifth comparative example, an acid treatment solution was prepared by adding 458 g of citric acid monohydrate and 598 g of sodium phosphate monohydrate to 200 l of seawater in the same manner as in the conventional acid treatment agent. Further, diluted solutions were prepared by adding 50 l of seawater (assuming the amount of seawater mixed during the acid treatment operation) to each of these acid treatment solutions. The seawater used had a pH of 8.17 and a specific gravity of 1.021 (water temperature of 17 ° C.), and the specific gravity of each acid treatment liquid and dilution liquid was less than 1.030. Table 5 shows the acid treatment solutions and the pH values after dilution.

  Compared to the sixth embodiment as a reference, the seventh embodiment in which the concentration is about half, the eighth embodiment in which the ratio of sodium sulfate and sodium hydrogen sulfate is about half, and the ratio of sodium sulfate is more than doubled. In any of the ninth examples, the pH change after dilution was small and kept within the range required as an acid treatment agent. With the formulation of the present invention, it has sufficient buffering capacity, acid treatment performance hardly changes even when diluted with seawater, it is comparable to the phosphorus-containing acid treatment liquid used as a comparative example, and can be effectively used as an acid treatment agent Was confirmed.

  As a result, when the acid treatment operation is performed using the organic acid of the present invention and the noble acid treatment agent using sodium sulfate and sodium hydrogen sulfate, sufficient acidity necessary for the acid treatment is maintained and the algae is surely maintained. In addition, the acid treatment operation in a short time as in the prior art has little adverse effect on the laver leaf body and the quality of the laver is not impaired. It was confirmed that the treatment was very effective.

Claims (5)

In the nori acid treatment agent containing organic acid,
Each compound of conjugated acid and base that does not contain phosphorus and forms a buffer solution by mixing with water and seawater are mixed with the organic acid, and the acidity of the organic acid and the buffer capacity of the buffer component A norilic acid treatment agent having a pH of 1 to 4 and an overall specific gravity of less than 1.03. In the seaweed acid treating agent according to claim 1,
The noble acid treatment agent, wherein each of the conjugated acid and base compounds is a substance that becomes a buffer solution having a maximum buffering action near pH 2 when mixed with a predetermined amount of seawater. In the seaweed acid treating agent according to claim 2,
Each of the conjugated acid and base compounds is sodium hydrogen sulfate and sodium sulfate. In the seaweed acid treating agent according to claim 3,
The noble acid treating agent, wherein the sodium hydrogen sulfate and sodium sulfate are dissolved in seawater from a solid crystalline state and mixed with the organic acid and seawater. In the seaweed acid treating agent according to claim 3 or 4,
The noble acid treating agent, wherein the blending molar ratio of sodium hydrogen sulfate and sodium sulfate is in the range of 10: 1 to 1:10.