JP6651982B2 - Iron supply material, iron supply material manufacturing method, and iron supply method - Google Patents

Description

  The present invention relates to an iron supply material, a method for producing an iron supply material, and an iron supply method.

  In recent years, in water bodies, biological production has been reduced due to a shortage of iron necessary for the growth of living organisms. For example, in the coastal sea area, seaweed beds, which are a community of seaweeds, disappear, causing so-called scorching, leading to a decrease in not only seaweeds but also many marine resources such as sea urchins, abalones, and krill.

  One of the causes of shore burning is a decrease in iron content in seawater. It is believed that iron in coastal areas was originally supplied to the sea through rivers, and it has been suggested that the amount of iron supplied has decreased due to deforestation and deforestation in recent years (Katsuhiko Matsunaga, Dies, see Kodansha, July 20, 1993).

  In response to such a problem of the coastal environment, a fertilizer for an aquatic environment in which a humic acid-containing substance serving as a chelator is mixed with steelmaking slag or coal molten ash that is an iron-containing substance has been proposed (Patent Document 1). Here, in Patent Literature 1, waste wood chips made into humus are used as humic acid-containing substances. In addition, a method has been proposed in which fish residues obtained by fermenting fishery processing residues are mixed with iron-containing substances as humic acid-containing substances (Patent Document 2).

  Furthermore, a method has been proposed in which an organic acid containing either gluconic acid or glutamic acid is mixed with the iron-containing substance to promote the elution of iron from the iron-containing substance (Patent Document 3).

JP 2006-212036 A JP 2006-345738 A JP-A-2011-176064

Effects of surface Fe (III) oxides in a steel slag on the formation of humic-like dark-colored polymers by the polycondensorship. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 418: 117-123.

The pH of seawater is maintained at 8.0 to 8.3, and it is an environment in which elution of iron ions from iron-containing substances is difficult. Even if the iron ions are eluted, they bind to hydroxide ions (OH ⁻ ) and precipitate as colloidal iron hydroxide. Therefore, in Patent Documents 1 to 3, the iron-containing substance is mixed with a weakly acidic humic acid-containing substance or the like. Thereby, iron ions are eluted from the iron-containing substance. The eluted iron ions form a complex with the ligand. That is, in Patent Documents 1 to 3, iron is supplied as a dissolved state.

  In fact, in Patent Literatures 1 and 2, the seaweed could be supplied by supplying iron to seawater, and the seaweeds could be prosperous.

  Further, as described in (Patent Document 3), it has been clarified by experimental studies by the inventors that the effect of promoting the elution of iron obtained by adding only an amino acid to an iron-containing substance is extremely low.

  Therefore, an object of the present invention is to promote the supply of iron from an iron-containing substance, and can stably maintain, a new and improved iron supply material, a method for producing an iron supply material, And a method of supplying iron.

In order to solve the above problems, according to an aspect of the present invention, characterized in that it contains a ferruginous material, the mixture of raw materials containing softwood as the main raw material and humic acid-containing substance formed by decomposition by microorganisms Is provided.

  Here, protocatechuic acid may be further included.

  It may further contain an amino acid.

  The amino acid may include at least one of glutamic acid and glycine.

  In addition, the iron-containing substance may include at least one of steel slag, scale, iron powder, iron oxide powder, iron sand, and coal molten ash.

According to another aspect of the present invention, characterized in that it comprises a ferruginous material, the mixing step of the raw material containing softwood as the main raw material is mixed with humic acid-containing substance formed by decomposition by microorganisms, iron A method of manufacturing a supply is provided.

  Here, in the mixing step, protocatechuic acid may be further mixed with the iron-containing substance and the humic acid-containing substance.

  In the mixing step, an amino acid may be further mixed with the iron-containing substance and the humic acid-containing substance.

  The amino acid may include at least one of glutamic acid and glycine.

  In addition, the iron-containing substance may include at least one of steel slag, scale, iron powder, iron oxide powder, iron sand, and coal molten ash.

  According to another aspect of the present invention, there is provided a method for supplying iron, wherein the above-described iron supply material is installed in water.

  According to this aspect, a humic acid-containing substance mainly containing softwood is used. Such humic acid-containing substances contain more protocatechuic acid. The humic acid-containing substance also functions as a source of amino acids. Therefore, the protocatechuic acid and the amino acid eluted from the humic acid-containing substance polymerize to form an amino acid-protocatechuic acid polymer. This amino acid-protocatechuic acid polymer reduces iron in the iron-containing substance and elutes it in water. And the amino acid-protocatechuic acid polymer functions as a chelator for iron in water. Therefore, more iron can be stably dissolved in water by using a humic acid-containing substance whose main material is softwood.

  As described above, according to the present invention, the supply (elution) of iron from an iron-containing substance can be promoted and stably maintained.

It is a graph which shows the elution behavior of iron of an example, a comparative example, and a control example in comparison.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<1. Study by the Inventor>
The inventor of the present invention has intensively studied iron supply materials capable of promoting the supply of iron from an iron-containing substance and stably maintaining the iron supply, and as a result, came to the iron supply material and the like according to the present embodiment. Therefore, first, a study performed by the present inventors will be described.

  Iron ions in the iron-containing substance hardly elute in a water environment, particularly in a sea area having a pH of 8.0 to 8.3. Therefore, in order to elute iron from the iron-containing substance, it is necessary to make the environment around the iron-containing substance weakly acidic or to add a reducing agent to the iron-containing substance. By mixing a humic acid-containing substance, which is an acidic substance, with a ferrous substance, a weakly acidic environment can be created, but seawater with a pH of 8.0 to 8.3 always exists around the ferrous substance. It is difficult to maintain a weakly acidic environment and stabilize elution.

On the other hand, in the method of adding a reducing agent to an iron-containing substance, by adding a necessary amount of the reducing agent to the iron-containing substance, it becomes easy to adjust the concentration and period of iron to be eluted. However, even if iron ions are eluted from the iron-containing substance, in the pH 8.0 to 8.3 sea area, ferrous iron becomes trivalent iron, and trivalent iron becomes colloidal iron by binding to an OH group and precipitates. (Fe ³⁺ + 3OH ⁻ → Fe (OH) ₃ ). Therefore, in order for iron to be present as a dissolved state in the water environment, it is necessary for iron ions to bind to the chelator and form a complex.

Therefore, the present inventors have studied substances having a reducing action and also having a function as a chelator. When selecting a chelator, the complexing ability must be considered. A complex using a chelator having a high complexing ability is stable, but is less likely to release Fe ²⁺ . For this reason, it is difficult for algae to take in iron. On the other hand, a complex using a chelator having a low complexing ability immediately separates Fe ²⁺ , and thus cannot increase the solubility of iron in seawater. Therefore, the present inventor studied a chelator capable of maintaining a certain iron concentration in the eluate. That is, the present inventor has studied a chelator having a complex forming ability that enables algae to take in Fe ²⁺ in a complex while stably retaining Fe ²⁺ in water. As a result, they came to think that a polymer (for example, an oligomer) was formed by mixing a reducing agent and a substance having a COOH group that is an iron complex formation site, and the polymer was reacted with iron ions. As the combination, it is known that glycine and catechol are polymerized in the soil environment (Non-patent Document 1). Therefore, a study is conducted using a substance having two hydroxyl groups that are adjacently bonded to an amino acid and a benzene ring. went. As a result, the present inventors have found that a polymer of protocatechuic acid (PCA) and an amino acid has a reducing action and functions as a chelator. Specifically, the polymer elutes Fe ²⁺ from the iron-containing substance by a reduction reaction of the OH group derived from protocatechuic acid, and functions as a chelator by the COOH group of the phenolic substance and the amino acid. Protocatechuic acid has a structure represented by the following chemical formula 1.

Specifically, the present inventor prepared a first sample by mixing an iron-containing substance, protocatechuic acid, and an amino acid, and performed an elution experiment in artificial seawater. As a result, the solution turned black and the iron concentration in the solution increased. From this, it was confirmed that the above-mentioned polymer was formed in the solution. It is known that the ratio of the absorbance E of the solution at a wavelength of 400 nm to the absorbance E at a wavelength of 600 nm, E ₄₀₀ / E ₆₀₀ , decreases as the molecular weight increases (Wang, ZD, Pant, BC, Langford). , CH, 1990. Spectroscopic and structural charactrization of a Laurentian fulvic acid: notes on origin of color. Anal. Chim. Therefore, the change in the ratio of the absorbance E with the passage of time was measured. As a result, it was confirmed that the absorbance ratio E ₄₀₀ / E ₆₀₀ decreased with time. Also in this respect, it was confirmed that the above-described polymer was formed in the solution.

  Further, the TOC (total organic carbon) of the solution was measured with a TOC meter. As a result, it was confirmed that the TOC maintained a certain value even after a lapse of time from the start of the dissolution test. Also in this regard, it was confirmed that the above-mentioned polymer was formed in the solution.

  Furthermore, the absorbance of the ultraviolet / visible part (200-400 nm) of the solution was measured. As a result, it was found that the absorbance decreased from the 10th day onward after the start of elution, and that the oxidation of carbon content occurred. Therefore, it was found that the above-mentioned polymer promoted the elution of divalent iron by oxidation.

  From the above results, in a system containing an iron-containing substance, protocatechuic acid, and an amino acid, a polymer of protocatechuic acid and an amino acid was formed, and with the oxidation of the carbon content of the polymer, It was presumed that iron content was reduced and eluted. It was presumed that the iron ions stably dissolved in the liquid by forming a complex with the protocatechuic acid-amino acid polymer.

On the other hand, based on the fact that the reducing action of the OH group has the effect of promoting the elution of iron, a similar elution test was performed by replacing the above-mentioned protocatechuic acid with gallic acid having one more OH group. Gallic acid is a phenolic acid substance having three hydroxyl groups adjacent to each other and bonded to a benzene ring as shown in the following chemical formula 2. As a result, little change in the color of the solution was observed, and the iron concentration in the solution did not increase. Also, the ratio E ₄₀₀ / E _{600 of} the absorbance hardly changed. On the other hand, TOC showed a significant value at the start of the dissolution test, but decreased significantly immediately thereafter. Therefore, it was presumed that the carbon content was not dissolved in any form. As the reason, once the solution adsorbed eluted gallate steelmaking slag surface during or advances the carbon content of the oxide in the gallic acid eluted in the solution, it is believed that is discharged from the system as CO ₂ Was. Thus, the absorbance of the eluate in the ultraviolet / visible region (200-400 nm) was measured. As a result, almost no change in absorbance was observed. From this, it was inferred that the decrease in TOC was due to the adsorption of gallic acid to the steelmaking slag surface.

  As a result, in the system containing gallic acid, a remarkable decrease in TOC was observed, and no change was observed in the absorbance in the ultraviolet / visible region (200-400 nm). It was presumed that the steel immediately adsorbed on the surface of the steelmaking slag. Therefore, it was presumed that gallic acid did not form a polymer with the amino acid and did not promote the elution of iron.

  According to the above findings, it is clear that an amino acid and protocatechuic acid form a polymer, and that such a polymer can promote the elution of iron from an iron-containing substance and stably dissolve iron. It became.

  Next, the present inventors focused on humic acid-containing substances as a source of protocatechuic acid and amino acids. Here, the humic acid-containing substance is a general term for organic matter generated in the process of decomposing animal and plant litter such as fallen leaves, fallen trees, and seafood residues by microorganisms using the same as an energy source. Humic acid-containing substances include protocatechuic acid and amino acids because protocatechuic acid and amino acids are produced during the decomposition of these raw materials (ie, animal and plant litter). Furthermore, the present inventors have intensively studied a humic acid-containing substance containing more protocatechuic acid. Specifically, the present inventor prepared a humic acid-containing substance using softwood as a raw material and a humic acid-containing substance using hardwood as a raw material. Furthermore, the present inventor prepared iron-containing substances, and performed an elution test of iron using these iron-containing substances and humic acid-containing substances. The details of the dissolution test will be described in Examples described later.

  As a result, in the test using the humic acid-containing material using softwood as a raw material, more iron was eluted than in the test using the humic acid-containing material using hardwood as a raw material. For this reason, it became clear that the humic acid-containing substance made from conifers contained more protocatechuic acid. Protocatechuic acid is known to be produced from coniferyl alcohol. Coniferyl alcohol is a precursor to lignin, a cell wall component of conifers. For this reason, it is inferred that the humic acid-containing substance made from softwood contains a larger amount of protocatechuic acid. Further, in a test using a humic acid-containing substance using hardwood as a raw material, the elution amount of iron was not sufficient. From these results, it is inferred that the humic acid-containing substance made from hardwood contains not only protocatechuic acid but also a lot of gallic acid. As described above, gallic acid is adsorbed on the steelmaking slag surface and inhibits elution of iron. As a result of the test, the inventor of the present invention has conceived of using a humic acid-containing substance mainly containing softwood as a source of protocatechuic acid and amino acids. The present inventor has arrived at the iron supply material and the like according to the present embodiment based on the above findings.

<2. Iron Supply Materials>
Next, the iron supply material according to the present embodiment will be described. The iron supply material of the present embodiment is characterized by containing an iron-containing substance and a humic acid-containing substance whose main material is softwood.

  As the iron-containing substance, at least one of iron slag, scale, iron powder, iron oxide powder, iron sand, and coal molten ash can be used.

  The iron-containing substance that supplies iron may be a solid that has a moderate effect, and a steel slag can be used. The steel slag includes steel slag generated from a steelworks and electric furnace slag (electric furnace steel slag) generated from an electric furnace maker. Steel slag generated from steel works is generated as a by-product in the steel manufacturing process. Steel slag is roughly classified into blast furnace slag and steelmaking slag. The slag used in the present invention is preferably a steelmaking slag. Blast furnace slag (about 0.4% by mass) having a lower iron content is lower than steelmaking slag (about 20% by mass). Therefore, when performing more efficient iron supply, it is preferable to use steelmaking slag. Of course, the slag used in the present invention is not limited to steelmaking slag.

  Steelmaking slag is a general term for slag generated when steel is manufactured from pig iron or scrap in a steelmaking furnace (a converter, an electric furnace, etc.), but the steelmaking slag used in the present invention is a converter-based steelmaking slag. Desirably. Converter steel slag has a stable composition and easy quality control compared to electric furnace steel slag. In recent years, in order to cope with the sophistication of steel quality, removal of impurities has become insufficient only by refining using a converter, and a high-grade steel manufacturing process to which processes (hot metal pretreatment, secondary refining) before and after the converter have been added. The molten iron pretreatment slag and secondary smelting slag generated from slag are also included in the converter steelmaking slag like the converter slag. The steelmaking slag used in the present invention can be supplied inexpensively and stably because it generates about 10% of the mass of crude steel in a mass ratio with respect to the amount of crude steel, and is very promising as an iron supply material. It is.

As the steelmaking slag used in the present invention, it is particularly desirable to use a steelmaking slag subjected to a carbonation treatment. Since steelmaking slag contains f-CaO (free lime) of about 1 to 2% by mass, it has a property of easily increasing the pH in water temporarily. For this reason, a carbonation treatment is performed to obtain a carbonized steelmaking slag in which f-CaO is CaCO ₃ . By making the steelmaking slag a carbonated steelmaking slag, the degree of pH rise of the elution water can be suppressed, and thus the elution of iron from the steelmaking slag can be further promoted. The carbonation treatment of steelmaking slag can be performed by bringing steelmaking slag into contact with carbon dioxide or carbonic acid-containing water. By this operation, CaO becomes CaCO ₃ , and CaCO ₃ is formed on the surface of the steelmaking slag, so that rapid elution of the remaining Ca ²⁺ can be suppressed. By performing such a carbonation treatment on the steelmaking slag, it is possible to prevent a temporary increase in pH in the water area, and thereby the dissolution effect of the present invention (that is, steelmaking by a polymer of protocatechuic acid and an amino acid) can be prevented. The effect of elution of iron from slag) is more positively exhibited.

  In addition, electric furnace slag may contain heavy metals other than iron that are unfavorable in a seaweed cultivation environment. For this reason, it is desirable to use steelmaking slag or blast furnace slag of the converter system. More preferably, converter steel slag is used.

  In addition to iron and steel slag, iron oxide, scales containing metallic iron, iron powder, iron oxide powder, iron sand, and coal molten ash may be used as the iron-containing substance.

  A typical example of the scale is a scale (eg, a mill scale) generated in a steel manufacturing process.

  Iron powder, iron oxide powder and iron sand are also preferable as the iron-containing substance. However, those containing iron oxide or metallic iron in a complex manner, such as slag, are more preferable because of their high reactivity with the chelator and high elution ability of iron ions.

Coal molten ash includes fine-powder boiler ash (fly ash) and molten ash (slag) from a spouted bed coal gasifier. The fly ash contains about 0.6 to 23% by mass of iron as iron oxide (Fe ₂ O ₃ ), but the molten ash generated in a reducing atmosphere in the integrated coal gasification combined cycle (IGCC) has an About 80% by mass of iron is present as ferrous iron.

The humic acid-containing substance according to the present embodiment is a source of protocatechuic acid and amino acids. As described above, protocatechuic acid polymerizes with amino acids to form a polymer (hereinafter, such a polymer is also referred to as “amino acid-protocatechuic acid polymer”). Of the amino acid-protocatechuic acid polymer, iron (i.e., Fe2 ⁺ ions) elutes into water from the iron-containing substance due to the reducing action of the OH group derived from protocatechuic acid. Further, since the amino acid-protocatechuic acid polymer has a COOH group derived from an amino acid and a COOH group derived from protocatechuic acid, it functions as a chelator of eluted Fe ²⁺ . That is, the amino acid-protocatechuic acid polymer forms a complex by coordinating to Fe ²⁺ . In the amino acid-protocatechuic acid polymer, an OH group as a reducing site and a COOH group as a complex forming site are structurally close to each other. Therefore, the iron complex formed by the amino acid-protocatechuic acid polymer can be stably present in water.

Since the OH group and the COOH group constituting protocatechuic acid are not close to each other, protocatechuic acid alone cannot stably exist in seawater. Specifically, when added to ferrous material protocatechuic acid alone, protocatechuic acid is temporarily bound to Fe ^2+, thereby dissociating Fe ^2+. Fe ²⁺ dissociated from protocatechuic acid is easily oxidized to Fe ³⁺ . The oxidized Fe ³⁺ becomes a hydroxide colloid as described above and precipitates. Therefore, the use of protocatechuic acid alone lowers the effect as a chelator. Therefore, in the present embodiment, protocatechuic acid is polymerized with an amino acid to form an amino acid-protocatechuic acid polymer, and this polymer functions as a reducing component of iron and a chelator. A complex using an amino acid-protocatechuic acid polymer as a chelator can stably dissolve iron (that is, Fe ²⁺ ) in water. In addition, algae can easily take up iron in the complex.

  The humic acid-containing substance according to the present embodiment is produced using softwood as a main raw material. That is, the humic acid-containing substance is produced by decomposing a raw material containing softwood as a main raw material with a microorganism. Here, the “main raw material” means, for example, a raw material that accounts for 30% by mass or more of all the raw materials. The proportion of softwood in all the raw materials is preferably at least 40% by mass, more preferably at least 50% by mass. Microorganisms use humic acid-containing materials as energy sources. The specific method for producing the humic acid-containing substance is not particularly limited, and a conventional production method can be arbitrarily applied.

  The humic acid-containing substance according to the present embodiment is produced using softwood as a main raw material, and therefore contains a particularly large amount of protocatechuic acid. Coniferyl alcohol, one of the raw materials of protocatechuic acid, is a precursor of lignin, a cell wall component of conifers. For this reason, it is presumed that the humic acid-containing substance according to the present embodiment contains many protocatechuic acids. Therefore, more iron can be eluted from the iron-containing substance into seawater.

  Further, softwood has a feature that corrosion hardly proceeds. For this reason, conventionally, conifers have not been used as a main raw material. Specifically, humic acid-containing substances were often produced using hardwood as a main raw material. However, the fact that the humus of conifers does not easily progress (in other words, the time required for corrosion) means that the corrosion of the humic acid-containing substance progresses slowly in seawater from a different viewpoint. That is, it is presumed that the humic acid-containing substance produced using softwood as a main raw material is slowly corroded in seawater, and elutes protocatechuic acid and amino acids generated by the corrosion into seawater. Therefore, further corrosion of the humic acid-containing substance and formation of the iron complex proceed simultaneously in seawater, and iron can be supplied to seawater stably and for a long time. That is, it is possible to expect a longer life of the iron supply material. If a longer life of the iron supply material is desired, a humic acid-containing substance that has undergone humification and a humic acid-containing substance that has undergone little corrosion may be mixed.

  Further, the humic acid-containing substance according to the present embodiment contains a large amount of inorganic nitrogen (nitrate nitrogen, ammonia nitrogen) and phosphorus (phosphate phosphorus) generated in the process of decomposing the raw material. Therefore, nitrogen and phosphorus essential for the growth of seaweed can be simultaneously supplied.

  By the way, the raw material of the humic acid-containing substance only needs to contain softwood as a main raw material, and may further contain other raw materials. Other raw materials include plant litter such as fallen leaves of broadleaf trees and fallen trees, and animal litter such as seafood residues. In addition, the softwood and the hardwood as raw materials may be waste wood chips or thinned wood.

  Here, other materials may be added to the iron supply material as long as the effects of the present embodiment are not impaired. For example, at least one of protocatechuic acid and an amino acid may be further added to the iron supply material. In particular, since the humic acid-containing substance according to the present embodiment is produced using softwood as a main raw material, there is a possibility that corrosion has not sufficiently progressed when it is put into seawater. Therefore, in the initial stage of the introduction, there is a possibility that protocatechuic acid and amino acids are deficient, and iron is not sufficiently eluted into seawater. Therefore, in order to compensate for the shortage of protocatechuic acid and amino acids, at least one of protocatechuic acid and amino acids may be added to the iron supply material. Here, the amino acids added to the iron supply material are preferably neutral and acidic amino acids when the iron supply material is introduced into seawater. In order for an amino acid to form a polymer with protocatechuic acid, the hydrogen of the amine group as a binding site must be in a state where it is not bound to another element. Therefore, the isoelectric point of the amino acid to be added must be lower than the pH of seawater (8.0 to 8.3). Therefore, it is preferable to add neutral and acidic amino acids having an isoelectric point lower than 8. Particularly preferred examples of amino acids are glutamic acid and glycine. Such amino acids are naturally contained in the humic acid-containing substance according to the present embodiment. Further, a humic acid-containing substance mainly composed of a material other than softwood may be further added. However, the content of the humic acid-containing substance from softwood as a raw material (that is, the humus of the conifer) is preferably 30% by mass or more, more preferably 40% by mass or more, of the total humic acid-containing material. It is more preferred that the content be at least mass%.

<3. Manufacturing method of iron supply material>
The method for producing (supplying method) the iron supply material according to the present invention includes the following method. That is, the humic acid-containing substance is added to the iron-containing substance such that the iron content eluted from the iron-containing substance becomes a desired amount. Here, as described above, the humic acid-containing substance is produced using softwood as a main raw material. Further, an amino acid and protocatechuic acid may be further added to the iron-containing substance. The amino acids are neutral and acidic amino acids, preferably glutamic acid and glycine. Further, a humic acid-containing substance mainly composed of a material other than softwood may be added to the iron-containing substance. However, the content of the humic acid-containing substance from softwood as a raw material (that is, the humus of the conifer) is preferably 30% by mass or more, more preferably 40% by mass or more in the total humic acid-containing material. It is more preferred that the content be at least mass%. The materials are then mixed well. The mixing method is not particularly limited, and may be the same as the conventional manufacturing method. Thereby, a supply material of iron is produced. Then, the iron supply material may be filled in a water-permeable bag or container in accordance with the place to be applied.

<4. Iron supply method using iron supply material>
The method of supplying iron using the iron supply material according to the present embodiment is not particularly limited, but the iron supply material may be installed in the water to be supplied with iron. Here, the setting method (application method) of the iron supply material is not particularly limited. For example, the iron supply material is placed in an organically decomposable and water-permeable bag (for example, a hemp bag or a coconut fiber bag). Submerged in the water bottom, buried in the water bottom or shoreline, or packed in a steel box and laid. As a result, the water infiltrates the iron supply material, and the nutrients from which the iron content eluted are supplied to the outside, and the growth effect of seaweeds and other organisms around the application is expected.

  The location where the iron supply material can be used is not particularly limited. For example, the iron supply material of the present embodiment can be used mainly in algae farms in the sea, brackish water, and land, and the effect of the present embodiment is mainly due to the growth of algae and microalgae. , It has an effect on breeding.

  The place where the iron supply material of the present embodiment exerts an effect includes a seaweed bed. A seaweed bed means a place where large seaweeds form communities on the water floor. The seaweed beds include, for example, a kelp seaweed bed composed of a kelp community, a galamo bed composed of Honda straws such as saw-toothed moku and oobamoku, and also an alame / kajime ground. It is known that iron is essential for the growth of seaweed, and examples of seaweed bed regeneration by supplying iron have been reported in various parts of Japan.

<1. Production of iron supply material>
Steelmaking slag, two kinds of humic acid-containing substances, and protocatechuic acid were prepared as raw materials for iron supply materials. Here, the steelmaking slag was obtained by grinding steelmaking slag having a particle size of 0 to 25 mm (greater than 0 and 25 mm or less) to 0.5 mm or less. The humic acid-containing substance was a humic acid-containing substance (hereinafter, also referred to as “Lb”) produced from hardwood, and a humic acid-containing substance (hereinafter, also “Lc”) produced from softwood.

  Next, as a control example, an iron supply material consisting only of steelmaking slag was prepared. Further, as a comparative example, a supply material of iron mixed with steelmaking slag and Lb was prepared. Further, as Example 1, a supply material of iron mixed with steelmaking slag and Lc was prepared. Further, as Example 2, a supply material of iron mixed with steelmaking slag, Lc, and protocatechuic acid was prepared. Here, the mixing ratio between the steelmaking slag and each humic acid-containing substance is based on the mixing ratio disclosed in Patent Document 1 (steelmaking slag: waste wood chips converted to humus = 6: 5 mass ratio). Were determined. The addition amount of protocatechuic acid was set so that it could sufficiently form a complex with iron (about 20% by mass or less) contained in the steelmaking slag. Table 1 summarizes the composition of the iron supply material. In Table 1, the concentration of PCA indicates the concentration in artificial seawater described later.

  Then, four Erlenmeyer flasks previously filled with 100 ml of artificial seawater were prepared, and the iron supply material prepared above was charged into each Erlenmeyer flask. Subsequently, elution with shaking at 125 rpm was performed at 25 ° C. for 430 hours.

  During the period of shaking elution, 1.2 ml of the eluate was periodically collected, and the collected eluate was centrifuged to remove the suspension. Then, 1 ml of the supernatant was collected, and 10 ml of pure water was added to the collected supernatant. Further, the pH of the supernatant was adjusted to less than 2 by subjecting the supernatant to acid treatment with hydrochloric acid. Thereby, the iron content in the supernatant was stabilized. Then, the concentration of iron was measured as the concentration of acid-soluble iron using an iron analyzer (FEA-07 manufactured by Kimoto Denshi Kogyo Co., Ltd.) using the luminol emission method. The measurement result was taken as the iron concentration in the eluate.

  The elution behavior for 430 hours (about 18 days) is shown in FIG. The horizontal axis in FIG. 1 shows the elapsed time (unit: time) from the start of the test, and the vertical axis (unit: μg / L, logarithmic axis) shows the iron concentration. As compared with the control example (steel slag alone), the elution of iron was promoted in Examples 1, 2 and Comparative Example. Further, the iron concentration on the last day of the experiment in the comparative example was 44 μg / L, whereas the iron concentration in Example 1 was 62 μg / L and that in Example 2 was 76.1 μg / L. Therefore, in Examples 1 and 2, the elution of iron was further promoted than in Comparative Examples. In the comparative example, it is presumed that gallic acid eluted from Lb adhered to the surface of the iron-containing substance and inhibited elution of iron. Therefore, it was clarified that the elution of iron from the iron-containing substance can be promoted by using softwood as the main raw material of the humic acid-containing substance.

  Further, in Example 2, the elution of iron was promoted more than in Example 1. This indicates that adding PCA to the iron supply material further enhances the elution promoting effect. In Example 2, since more amino acid-protocatechuic acid was generated than in Example 1, it is considered that the elution of iron was promoted.

By the way, in Example 2, the concentration of iron reached 770 μg / L in the early stage of elution (specifically, at the time when about 30 hours had elapsed from the start of the test), but then decreased. The present inventor considers the reason as follows. That is, in Example 2, since protocatechuic acid was added to the iron supply material, it is presumed that protocatechuic acid was present in excess of the amino acid supplied from the humic acid-containing substance. Excess protocatechuic acid reduces the iron content in the iron-containing substance and elutes it into seawater. For this reason, the concentration of iron rapidly increases. Then, the amino acid-protocatechuic acid polymer forms a complex with the eluted iron (that is, Fe ²⁺ ). However, the eluted Fe ²⁺ is present in excess of the amino acid-protocatechuic acid polymer present in water. For this reason, some Fe ²⁺ cannot form a complex with the amino acid-protocatechuic acid, and is easily oxidized to Fe ³⁺ . Then, Fe ³⁺ becomes iron hydroxide and precipitates. Therefore, it is inferred that the above-described phenomenon has occurred.

As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those skilled in the art to which the present invention pertains can conceive various changes or modifications within the scope of the technical idea described in the claims. It is understood that these also belong to the technical scope of the present invention.

Claims (11)

Ferruginous material and supply material for iron raw material including softwood as the main raw material, characterized in that it contains a mixture of humic acid-containing substance formed by decomposition by microorganisms.   The iron supply material according to claim 1, further comprising protocatechuic acid.   The iron supply material according to claim 1, further comprising an amino acid.   The iron supply material according to claim 3, wherein the amino acid contains at least one of glutamic acid and glycine.   The iron component according to any one of claims 1 to 4, wherein the iron-containing substance contains at least one of steel slag, scale, iron powder, iron oxide powder, iron sand, and coal molten ash. Supplies. Ferruginous material and the raw material containing softwood as the main raw material, characterized in that it comprises a mixing step of mixing a humic acid-containing substance formed by decomposition by microorganisms, the production method of the feed material iron.   The method according to claim 6, wherein in the mixing step, protocatechuic acid is further mixed with the iron-containing substance and the humic acid-containing substance.   The method according to claim 6, wherein in the mixing step, an amino acid is further mixed with the iron-containing substance and the humic acid-containing substance.   9. The method according to claim 8, wherein the amino acid contains at least one of glutamic acid and glycine.   The iron component according to any one of claims 6 to 9, wherein the iron-containing substance includes at least one of steel slag, scale, iron powder, iron oxide powder, iron sand, and coal molten ash. Manufacturing method of supply material.   A method for supplying iron, comprising placing the iron supply material according to any one of claims 1 to 5 in water.

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