Foamed glass composite material

Abstract

The purpose of the present disclosure is to provide a novel foamed glass composite material capable of removing environmental pollutants such as phosphorus.　The present disclosure relates to a foamed glass composite material containing: foamed glass; iron or a compound thereof; and lanthanum or a compound thereof, and a phosphorus adsorbent containing this foamed glass composite material.

Description

Foam Glass Composite

[0001] The present disclosure relates to foam glass composite materials and the like.

[0002] Wastewater from industries, households, and agricultural areas contains nutrients such as nitrogen and phosphorus that lead to eutrophication. It is known that the flow of such wastewater into rivers, lakes, and oceans can lead to the occurrence of large-scale red tides and blue-green algae blooms. In urban areas, wastewater is primarily purified at sewage treatment plants. However, the sewerage coverage rate per capita in Japan is only 78.8% (as of FY2017). In areas without sewer systems, such as suburban and depopulated areas, septic tanks are installed as wastewater treatment systems. Typical septic tanks do not have the ability to remove nitrogen and phosphorus. Therefore, the compliance rate for total nitrogen and total phosphorus in lakes and ponds (FY2015) was low at 51.2%. Therefore, even in areas without sewer systems, advanced nitrogen and phosphorus removal treatment is required for septic tanks.

[0003] Furthermore, from the perspective of phosphorus resource depletion, it is necessary to recover phosphorus from wastewater. Conventional methods for removing phosphorus from water include coagulation-sedimentation, which uses metal salts or lime as a coagulant, biological phosphorus removal (activated sludge method), which utilizes microbial metabolism, and adsorption. The coagulation-sedimentation method requires the addition of a large amount of expensive coagulant and produces a large amount of difficult-to-treat sludge, resulting in poor initial and running cost performance. The biological phosphorus removal (activated sludge method) requires meticulous management of dissolved oxygen concentration and sludge management in the final settling tank, as well as the treatment and disposal of sludge with a high phosphorus content. Therefore, applying these methods to decentralized wastewater treatment systems such as septic tanks requires not only additional equipment but also constant operational management by experts.

[0004] In Japan, the Act on Promotion of Effective Utilization of Resources was enacted in 2001, and efforts to promote the 3Rs (reduce, reuse, and recycle) have been promoted in the glass industry. Glass has the characteristic that it can maintain its quality no matter how many times it is recycled, making it possible to recycle it. However, currently, glass products other than beer bottles are not sufficiently collected, and most of them are landfilled, resulting in problems such as soil contamination. Furthermore, there are concerns about the construction of waste disposal sites in the future, making it necessary to find new ways to effectively utilize discarded glass (waste glass).

[0005] As a method for solving the above problems, in recent years, a method has been proposed in which waste glass is used to remove water pollutants such as phosphorus. For example, Patent Document 1 proposes a phosphate ion adsorbent containing foam glass made from waste glass as a raw material. Patent Document 1 describes adding a material containing at least one of calcium, magnesium, and iron to foam glass, but does not mention or even suggest adding lanthanum. Patent Document 2 proposes a porous functional material in which a limonite component is supported on a porous support, foam glass. Patent Document 2 describes a porous functional material in which iron or manganese is supported on foam glass, but does not mention or suggest supporting lanthanum.

[0006] JP 2011-161398 A JP 2015-192977 A

[0007] An object of the present disclosure is to provide a novel foam glass composite material that can remove water pollutants such as phosphorus.

[0008] The present inventors have conducted extensive research to develop a novel foam glass composite material capable of removing water pollutants such as phosphorus, and as a result have found that a composite material in which iron and lanthanum are supported on foam glass has an excellent ability to adsorb water pollutants, particularly phosphorus. The present disclosure has been completed based on this finding.

[0009] That is, the present disclosure is as follows. Item 1. A foam glass composite material containing foam glass, iron or a compound thereof, and lanthanum or a compound thereof. Item 2. The foam glass composite material according to Item 1, wherein the content of the lanthanum or a compound thereof is 0.01% by mass or more. Item 3. The foam glass composite material according to Item 1 or 2, wherein the content of the iron or a compound thereof is 0.005% by mass or more. Item 4. The foam glass composite material according to any one of Items 1 to 3, wherein the average particle size of the foam glass is 75 mm or less. Item 5. The foam glass composite material according to any one of Items 1 to 4, obtained by firing foam glass, iron or a compound thereof, and lanthanum or a compound thereof at 700°C or less. Item 6. The foam glass composite material according to any one of Items 1 to 5, which is used to remove phosphorus contained in wastewater. Item 7. A method for producing the foam glass composite material according to Item 1, comprising a step of mixing foam glass, iron or a compound thereof, and lanthanum or a compound thereof. Item 8. Item 7. The method for producing a foam glass composite material according to Item 7, wherein the step of mixing the foam glass with iron or a compound thereof and lanthanum or a compound thereof comprises: a step of supporting iron or a compound thereof on the foam glass to obtain an iron-loaded foam glass composite material; and a step of supporting lanthanum or a compound thereof on the iron-loaded foam glass composite material to obtain an iron-lanthanum-loaded foam glass composite material. Item 9. The method for producing a foam glass composite material according to Item 8, further comprising a step of firing the iron-lanthanum-loaded foam glass composite material at 700°C or less. Item 10. A phosphorus adsorbent comprising the foam glass composite material according to any one of Items 1 to 6. Item 11. A wastewater treatment device comprising the phosphorus adsorbent according to Item 10. Item 12. A method for adsorbing phosphorus, comprising contacting the phosphorus adsorbent according to Item 10 with a phosphorus-containing liquid. Item 13. A method for removing phosphorus, comprising adsorbing and removing phosphorus from wastewater using the phosphorus adsorbent according to Item 10. Item 14. Item 14. A method for adsorbing and removing phosphorus from wastewater, comprising adsorbing and removing a foam glass composite material containing foam glass, iron or a compound thereof, and lanthanum or a compound thereof. Item 15. A foam glass composite material obtained by the method for producing a foam glass composite material according to any one of Items 7 to 9.Item 16. A phosphorus adsorbent comprising a foam glass composite material obtained by the method for producing a foam glass composite material according to any one of Items 7 to 9.

[0010] In addition, in the present disclosure, the foam glass composite material or phosphorus adsorbent defined by the manufacturing process is described as a product-by-process claim because it is currently impossible or impractical to specify all of the components contained therein or the structure thereof.

[0011] According to the present disclosure, a novel foam glass composite material capable of removing environmental pollutants such as phosphorus can be provided. The foam glass composite material of the present disclosure has excellent ability to adsorb water pollutants, particularly phosphorus, and is therefore useful as a phosphorus adsorbent.

[0012] FIG. 1 is a graph showing the relationship between the lanthanum loading rate in foam glass and the phosphate-phosphorus adsorption rate. FIG. 2 is a graph showing the relationship between the firing temperature and the phosphate-phosphorus adsorption rate of foam glass supporting 3.5% by mass of lanthanum. FIG. 3 is a graph showing the relationship between the iron loading rate and the phosphate-phosphorus adsorption rate in iron-lanthanum (3.5% by mass)-supported foam glass when the initial phosphate-phosphorus concentration is 10 mg-P / L. FIG. 4 is a graph showing the relationship between the iron loading rate and the phosphate-phosphorus adsorption rate in iron-lanthanum (3.5% by mass)-supported foam glass when the initial phosphate-phosphorus concentration is 100 mg-P / L. FIG. 5 is a graph showing the relationship between the iron loading rate and the absorbance at a wavelength of 660 nm in iron-lanthanum (3.5% by mass)-supported foam glass when the initial phosphate-phosphorus concentration is 100 mg-P / L. FIG. 6 is a graph showing the relationship between the iron loading rate in foam glass and the specific surface area of ​​a foam glass composite material. FIG. 7 is a graph showing the relationship between the lanthanum loading rate and the phosphate-phosphorus adsorption rate on iron (0.1% by mass)-supported foam glass. FIG. 8 is a graph showing the change in the amount of phosphate-phosphorus adsorption over time for iron (0.1% by mass)-lanthanum (2% by mass)-supported foam glass when the initial phosphate-phosphorus concentration is 1 mg-P / L. FIG. 9 is a graph showing the change in the amount of phosphate-phosphorus adsorption over time for iron (0.1% by mass)-lanthanum (2% by mass)-supported foam glass when the initial phosphate-phosphorus concentration is 10 mg-P / L. FIG. 10 is a graph showing the relationship between the equilibrium concentration and equilibrium adsorption amount of phosphate-phosphorus for iron (0.1% by mass)-lanthanum (2% by mass)-supported foam glass. FIG. 11 is a schematic diagram of a phosphorus removal device used in an adsorption experiment using actual wastewater. 12 is a graph showing the change in phosphate-phosphorus concentration over time in wastewater 1 (initial phosphate-phosphorus concentration of 5 mg-P / L) when an iron (0.1 mass%)-lanthanum (3.5 mass%)-supported foam glass composite material or foam glass was used. FIG. 13 is a graph showing the change in phosphate-phosphorus concentration over time in wastewater 2 (initial phosphate-phosphorus concentration of 15 mg-P / L) when an iron (0.1 mass%)-lanthanum (3.5 mass%)-supported foam glass composite material or foam glass was used.FIG. 14 is a graph showing the change over time in the phosphate-phosphorus concentration in wastewater 3 (initial phosphate-phosphorus concentration 50 mg-P / L) when an iron (0.1 mass%)-lanthanum (3.5 mass%)-supported foam glass composite material or foam glass was used.

[0013] 1. Foam Glass Composite Material The foam glass composite material of the present disclosure contains (1) foam glass, (2) iron or a compound thereof, and (3) lanthanum or a compound thereof. The foam glass composite material of the present disclosure can also be referred to as an iron-lanthanum-supported foam glass composite material in which (1) foam glass is supported with (2) iron or a compound thereof, and (3) lanthanum or a compound thereof. The foam glass composite material of the present disclosure has iron or a compound thereof and lanthanum or a compound thereof supported on the surface of porous foam glass, and the iron or a compound thereof and lanthanum or a compound thereof adsorb water pollutants such as phosphorus, thereby enabling the removal of water pollutants such as phosphorus.

[0014] Foam glass Foam glass is glass having many pores. Foam glass can be produced by a known method. For example, it can be produced by firing a mixture of crushed glass and a foaming agent. An example of a method for producing foam glass will be described in detail below.

[0015] First, glass (hereinafter referred to as "raw glass") used as a raw material for foam glass is crushed. The type of raw glass is not particularly limited, and examples thereof include soda-lime glass, borosilicate glass, aluminosilicate glass, and crystal glass. The raw glass may be waste glass derived from, for example, cathode ray tubes, liquid crystal displays, plasma displays, solar panels, or the like, or new manufactured glass. The method for crushing the raw glass is not particularly limited, and the raw glass may be crushed using, for example, a commercially available vibration mill or ball mill. As a preliminary step to crushing, the raw glass may be crushed to a size of about 10 mm using, for example, a jaw crusher, and the crushed glass may be crushed. The particle size of the crushed glass (hereinafter referred to as "crushed glass") is not particularly limited, but is preferably small so that the crushed glass and the foaming agent are uniformly mixed. For example, after crushing the raw glass, particle size classification is preferably performed using a sieve with a mesh size of 200 μm or less, so that the particle size of the crushed glass is 200 μm or less.

[0016] Next, the crushed glass and a foaming agent are mixed. The type of foaming agent is not particularly limited, and examples thereof include silicon carbide (SiC), silicon nitride (SiN), calcium carbonate (CaCO ３ ), dolomite (CaMg(CO ３ ) ２ ), magnesium carbonate (MgCO ３Materials containing calcium, magnesium, or iron (such as shells) can be used. Such foaming agents generate gas at the temperature at which the glass softens, resulting in the formation of numerous pores within the glass, producing foamed glass. The amount of foaming agent added is not particularly limited, but is preferably 0.1 to 5 mass% and more preferably 0.2 to 2.0 mass% relative to the raw glass (see JP 2011-161398 A). Using the foaming agent within this range ensures sufficient foaming and prevents excessive foaming, which could lead to a decrease in the strength of the foamed glass. When mixing the crushed glass and the foaming agent, a material containing at least one of calcium, magnesium, or iron can also be added. Specific examples of such materials include calcium hydroxide, magnesium carbonate, magnesium hydroxide, red iron oxide, and ferrite. The amount of the material added is not particularly limited, but is preferably 1 to 20 mass% and more preferably 5 to 15 mass% relative to the raw glass (see JP 2011-161398 A). Using the material within this range can improve the adsorption rate of phosphorus and other substances.

[0017] Next, the mixture of pulverized glass and foaming agent is fired. The firing temperature and time may be appropriately set depending on the type of glass and foaming agent so that the glass foams appropriately. The firing temperature is, for example, 600 to 1150°C. When the raw glass is soda-lime glass, the firing temperature is preferably 800 to 1000°C, and more preferably, the glass is melted at 800°C and then foamed at 900°C. If the firing temperature is within this range, the glass is sufficiently softened to properly form pores, and the glass does not become too soft, so that the formed pores can be prevented from being re-closed. The firing time is, for example, 1 to 60 minutes, preferably 5 to 10 minutes. If the firing time is within this range, sufficient foaming occurs and the formed pores can be prevented from being re-closed or the bubbles can be prevented from sticking together, resulting in a loss of fineness in the surface (see JP 2011-161398 A).

[0018] Foam glass is produced by the above steps. The produced foam glass may be used as is in a lump form, or may be crushed before use. The average particle size of the foam glass when used as is in a lump form is not particularly limited, but is preferably 75 mm or less, more preferably 2 to 75 mm, even more preferably 5 to 40 mm, and particularly preferably 10 to 20 mm. The average particle size of the foam glass after crushing is not particularly limited, but is preferably 2 mm or less, more preferably 1 mm or less, and even more preferably 0.6 mm or less.

[0019] In addition, foam glass is commercially available under the trade names Supersol (registered trademark), Miraclesol, Bubglass (registered trademark), Porous α (registered trademark), etc., and these commercially available products can also be used.

[0020] Foam glass is porous and lightweight, making it easy to transport, move, handle, etc. Furthermore, foam glass is structurally chemically stable, making it less susceptible to deterioration, leaching, etc.

[0021] Iron or its compound The iron or its compound contained in the foam glass composite material of the present disclosure is not particularly limited as long as it contains iron, and examples thereof include iron atoms (Fe), iron ions (Fe ２＋ , Fe ３＋ ), iron oxide, iron hydroxide, iron oxyhydroxide, iron phosphate, etc. Also, water-soluble iron compounds used as raw materials may be used. Examples of iron oxide contained in the foam glass composite material include iron (II) oxide (FeO), iron (II, III) oxide (Fe ３ O ４ ), iron (III) oxide (Fe ２ O ３ Examples of iron hydroxides contained in the foam glass composite material include goethite (FeO(OH)), iron(II) hydroxide (Fe(OH) ２ ), iron(III) hydroxide (Fe(OH) ３ Examples of iron oxyhydroxide contained in the foam glass composite material include goethite (FeO(OH)). Examples of iron phosphate contained in the foam glass composite material include iron(III) phosphate (FePO ４Examples of water-soluble iron compounds contained in the foam glass composite material include iron(II) chloride (FeCl ２ ), iron(III) chloride (FeCl ３ ), iron(II) nitrate (Fe(NO ３ ) ２ ), iron(III) nitrate (Fe(NO ３ ) ３ ), iron(II) sulfate (FeSO ４ ), iron (III) sulfate (Fe ２ (SO ４ ) ３ ), iron(II) acetate (Fe(CH ３ CO ２ ) ２ ) or hydrates thereof.

[0022] The iron content in the foam glass composite material can be measured, for example, by X-ray fluorescence analysis. The content of iron or its compounds in the foam glass composite material indicates the theoretical loading rate in terms of iron (metal) by mass. The iron content in the foam glass composite material does not include the content of iron derived from the glass contained within the foam glass. The content of iron or its compounds in the foam glass composite material is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, even more preferably 0.05 to 0.5 parts by mass, and particularly preferably 0.1 to 0.25 parts by mass, per 100 parts by mass of foam glass. That is, the content of iron or its compounds in the foam glass composite material is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.05 to 0.5% by mass, and particularly preferably 0.1 to 0.25% by mass.

[0023] Lanthanum or Compound Thereof The lanthanum or compound thereof contained in the foam glass composite material of the present disclosure is not particularly limited as long as it contains lanthanum, and examples thereof include lanthanum atom (La), lanthanum ion, lanthanum oxide, lanthanum hydroxide, lanthanum phosphate, etc. Water-soluble lanthanum compounds used as raw materials may also be used. Examples of water-soluble lanthanum compounds contained in the foam glass composite material include lanthanum chloride (LaCl), ３ ), lanthanum nitrate (La(NO３ ) ３ ), lanthanum sulfate (La ２ (SO ４ ) ３ ), lanthanum acetate (La(CH ３ CO ２ ) ３ ) or hydrates thereof.

[0024] The lanthanum content in the foam glass composite material can be measured, for example, by X-ray fluorescence analysis. The lanthanum content in the foam glass composite material refers to the support rate in terms of mass of lanthanum (metal) and is a theoretical value. The content of lanthanum or a compound thereof contained in the foam glass composite material is preferably 0.01 parts by mass or more, more preferably 0.5 to 3.5 parts by mass, and even more preferably 2 to 3.5 parts by mass, per 100 parts by mass of foam glass. That is, the content of lanthanum or a compound thereof in the foam glass composite material is preferably 0.01% by mass or more, more preferably 0.5 to 3.5% by mass, and even more preferably 2 to 3.5% by mass. By setting the content of each component within the above ranges, a foam glass composite that can exhibit higher phosphorus adsorption performance can be obtained.

[0025] As described above, the foam glass composite material of the present disclosure contains foam glass, iron or a compound thereof, and lanthanum or a compound thereof. However, any foam glass composite material may be used as long as it contains foam glass, iron or a compound thereof, and lanthanum or a compound thereof as raw materials, and may include, for example, the raw materials "foam glass composite material obtained from foam glass, iron or a compound thereof, and lanthanum or a compound thereof," "foam glass composite material produced by reacting foam glass, iron or a compound thereof, and lanthanum or a compound thereof," etc. Since it is impossible or impractical to identify all of the components contained in the "foam glass composite material obtained from foam glass, iron or a compound thereof, and lanthanum or a compound thereof" as referred to here, the foam glass composite material is recited as a product-by-process claim.

[0026] The BET specific surface area of ​​the foam glass composite material is 1 m ２ / g or more is preferable, and 2m ２ / g or more is more preferable, and 4m ２ / g or more. ２ The upper limit of the BET specific surface area is not particularly limited, but is preferably 20 m ２ / g.

[0027] The foam glass composite material is preferably particulate. The particle size is not limited and can be appropriately set depending on the application, use conditions (phosphorus adsorption conditions), etc. For example, the average particle size may be about 1 to 30 mm. When the foam glass composite material is used as a phosphorus adsorbent in a septic tank, from the viewpoint of handling, the average particle size is preferably 5 mm or more, more preferably 5 to 30 mm, and even more preferably 10 to 20 mm. These particle size adjustments can be performed using known methods such as classification and pulverization. The particle shape of the foam glass composite material is also not limited and may be any form, such as agglomerated, spherical, flake-like, or amorphous. In particular, agglomerated or spherical shapes are preferred from the viewpoints of packing into a fixed bed (such as a column) and liquid flowability.

[0028] 2. Manufacturing Method of Foam Glass Composite Material The manufacturing method of the foam glass composite material of the present disclosure includes a step of mixing foam glass with iron or a compound thereof and lanthanum or a compound thereof. The manufacturing method is not particularly limited as long as a foam glass composite material containing foam glass, iron or a compound thereof, and lanthanum or a compound thereof can be obtained.

[0029] Examples of the production method include: (1) a method of simultaneously loading iron or a compound thereof and lanthanum or a compound thereof onto foam glass to obtain a foam glass composite material in which iron or a compound thereof and lanthanum or a compound thereof are loaded onto the foam glass (iron-lanthanum-loaded foam glass composite material); (2) a method of loading iron or a compound thereof onto foam glass to obtain an iron-loaded foam glass composite material, and then loading lanthanum or a compound thereof onto the iron-loaded foam glass composite material to obtain a foam glass composite material in which iron or a compound thereof and lanthanum or a compound thereof are loaded onto the foam glass (iron-lanthanum-loaded foam glass composite material); and (3) a method of loading lanthanum or a compound thereof onto foam glass to obtain a lanthanum-loaded foam glass composite material, and then loading iron or a compound thereof onto the lanthanum-loaded foam glass composite material to obtain a foam glass composite material in which iron or a compound thereof and lanthanum or a compound thereof are loaded onto the foam glass (iron-lanthanum-loaded foam glass composite material). Among the above-mentioned production methods, from the viewpoint of increasing the specific surface area of ​​the foam glass and improving the lanthanum loading rate, a preferred method is (2) to load iron or a compound thereof onto foam glass to obtain an iron-loaded foam glass composite, and then load lanthanum or a compound thereof onto the iron-loaded foam glass composite to obtain a foam glass composite material in which iron or a compound thereof and lanthanum or a compound thereof are loaded onto the foam glass (iron-lanthanum-loaded foam glass composite material). The production method (2) can be said to be a method comprising a step of loading iron or a compound thereof onto foam glass to obtain an iron-loaded foam glass composite material, and a step of loading lanthanum or a compound thereof onto the iron-loaded foam glass composite material to obtain an iron-lanthanum-loaded foam glass composite material.

[0030] In the above (2), examples of the step of loading iron or a compound thereof onto foam glass to obtain an iron-loaded foam glass composite material include a method of immersing foam glass in an iron aqueous solution prepared by dissolving a water-soluble iron compound in water, followed by drying, and a method of spraying the iron aqueous solution onto the foam glass. The water-soluble iron compound is a compound that converts iron ions (Fe ２＋ , Fe ３＋ There is no particular limitation on the compound as long as it releases iron. Examples of such water-soluble iron compounds include iron(II) chloride (FeCl２ ), iron(III) chloride (FeCl ３ ), iron(II) nitrate (Fe(NO ３ ) ２ ), iron(III) nitrate (Fe(NO ３ ) ３ ), iron(II) sulfate (FeSO ４ ), iron (III) sulfate (Fe ２ (SO ４ ) ３ ), iron(II) acetate (Fe(CH ３ CO ２ ) ２ The concentration of the aqueous iron solution used may be adjusted appropriately so that the iron content in the foam glass composite material, which is the final product, is 0.005 parts by mass or more per 100 parts by mass of the foam glass.

[0031] Examples of the step of supporting lanthanum or a compound thereof on the iron-supported foam glass composite material include a method of immersing the iron-supported foam glass composite material in a lanthanum aqueous solution prepared by dissolving water-soluble lanthanum or a compound thereof in water, followed by drying, and a method of spraying the lanthanum aqueous solution on the iron-supported foam glass composite material. ３＋ There is no particular limitation on the compound as long as it releases lanthanum. Examples of such water-soluble lanthanum compounds include lanthanum chloride (LaCl). ３ ), lanthanum nitrate (La(NO ３ ) ３ ), lanthanum sulfate (La ２ (SO ４ ) ３ ), lanthanum acetate (La(CH ３ CO ２ ) ３ The concentration of the lanthanum aqueous solution used may be adjusted appropriately so that the lanthanum content in the final product, the iron-lanthanum-supported foam glass composite material, is 0.01 parts by mass or more per 100 parts by mass of the foam glass.

[0032] The amount of iron supported per 100 parts by mass of foam glass is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, even more preferably 0.05 to 0.5 parts by mass, and particularly preferably 0.1 to 0.25 parts by mass, and the amount of lanthanum supported per 100 parts by mass of the foam glass is preferably 0.01 parts by mass or more, more preferably 0.5 to 3.5 parts by mass, and even more preferably 2 to 3.5 parts by mass.

[0033] The resulting foam glass composite material is preferably further dried and then fired. Drying and firing the foam glass composite material strengthens the bond between the foam glass and lanthanum, preventing lanthanum from peeling off and improving the phosphorus adsorption performance of the foam glass composite material. The drying temperature is preferably 50°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. The upper limit of the drying temperature is not particularly limited, but is generally 200°C or lower, preferably 150°C or lower. The drying time depends on the type of foam glass, the drying temperature, etc., but is basically set to the time required to remove the moisture content. It is also preferable to perform drying with excellent breathability, such as in a hot air oven. From the viewpoint of preventing lanthanum and the like from peeling off and achieving a high phosphorus adsorption rate, the firing temperature is usually 750°C or lower, preferably 250 to 700°C, more preferably 260 to 400°C, even more preferably 300 to 380°C, and particularly preferably 330 to 370°C.

[0034] The firing atmosphere is not particularly limited, and may be, for example, an oxidizing atmosphere (air), a reducing atmosphere, an inert gas atmosphere, etc. The firing time can also be appropriately adjusted depending on the firing temperature, etc.

[0035] The obtained fired body may be further processed depending on the specific usage environment. For example, when a foam glass composite material is produced using relatively large foam glass, it may be used as is, or may be used after processing such as crushing and classification as necessary. The foam glass composite material of the present disclosure obtained in this manner has iron and lanthanum supported on the surface of the porous foam glass, and the iron and lanthanum adsorb water pollutants such as phosphorus, thereby removing the water pollutants. Therefore, the foam glass composite material of the present disclosure exhibits excellent environmental purification activity. Specifically, the foam glass composite material of the present disclosure can be used as a water pollutant remover for removing phosphorus, arsenic, etc. from water. The foam glass composite material of the present disclosure can be used as a phosphorus adsorbent, particularly because it has excellent adsorption ability for phosphorus (phosphate ions, phosphate phosphorus, dissolved inorganic phosphate, etc.) in wastewater.

[0036] 3. Phosphorus Adsorbent The phosphorus adsorbent of the present disclosure includes the foam glass composite material described above. Accordingly, the phosphorus adsorbent of the present disclosure includes foam glass, iron or a compound thereof, and lanthanum or a compound thereof.

[0037] The BET specific surface area of ​​the phosphorus adsorbent is 1 m ２ / g or more is preferable, and 2m ２ / g or more is more preferable, and 4m ２ / g or more is more preferable. ２ The upper limit of the BET specific surface area is not particularly limited, but is preferably 20 m ２ / g.

[0038] The phosphorus adsorbent is preferably particulate. Its particle size is not limited and can be appropriately set depending on the application, use conditions (phosphorus adsorption conditions), etc. For example, the average particle size may be about 1 to 30 mm. When used in a septic tank, from the viewpoint of handling, it is preferably 5 mm or more, more preferably 5 to 30 mm, and even more preferably 10 to 20 mm. These particle size adjustments can be performed using known methods such as classification and pulverization. Furthermore, the particle shape of the phosphorus adsorbent is also not limited and may be any form such as agglomerated, spherical, flake-like, or irregular. In particular, agglomerated or spherical shapes are preferred from the viewpoints of packing into a fixed bed (such as a column) and liquid flowability.

[0039] The phosphorus to be adsorbed is not particularly limited as long as it contains phosphorus element, and examples thereof include ions containing phosphorus element (phosphate ions). Phosphate ions include orthophosphate (H ３ P.O. ４ ) dissociates, orthophosphate ion (PO ４ ３－ ), dihydrogen phosphate ion (H ２ P.O. ４ － ) and hydrogen phosphate ion (HPO ４ ２－ ), phosphite ions, polyphosphate ions, etc.

[0040] Although this varies depending on the experimental conditions, for example, the phosphorus adsorption capacity of the phosphorus adsorbent of the present disclosure is 1.4 mg / g or more, and a higher phosphorus adsorption capacity is preferable. The phosphorus adsorption rate of the phosphorus adsorbent of the present disclosure is approximately 1.6 to 6.6 mg / L / hour (see Examples). As such, the phosphorus adsorbent of the present disclosure has high phosphorus adsorption performance (high phosphorus adsorption capacity and fast phosphorus adsorption rate), and therefore can be used to remove phosphorus from water. In particular, the phosphorus adsorbent of the present disclosure has high phosphorus adsorption performance at phosphorus concentrations (1 to 5 mg / L) (low concentration range) that occur in septic tank wastewater, and therefore can be applied to decentralized wastewater treatment devices, particularly septic tanks.

[0041] The present disclosure also encompasses a method for adsorbing phosphorus, the method comprising the step of contacting the phosphorus adsorbent with a liquid containing phosphorus. The phosphorus contained in the liquid is not particularly limited as long as it contains elemental phosphorus, and examples thereof include ions containing elemental phosphorus (phosphate ions), phosphate-type phosphorus, and dissolved inorganic phosphate.

[0042] In the adsorption method of the present disclosure, the form of the adsorbent is not particularly limited as long as it can be brought into contact with the phosphorus-containing liquid. For example, either a batch method in which the adsorbent is brought into contact with the liquid, or a continuous method in which the adsorbent is brought into contact with the liquid while continuously supplying and flowing the liquid, may be used. In addition, a fixed bed process or a moving bed process may also be used.

[0043] The phosphorus-containing liquid (particularly, a liquid containing water as a medium) is not particularly limited, and examples thereof include wastewater such as industrial wastewater, domestic wastewater, and agricultural wastewater; lake water, seawater, and river water. The phosphate concentration of these liquids is also not limited, and can be adjusted in advance to, for example, about 0.1 to 200 mg-P / L. The unit of concentration (mg-P / L) is the concentration of phosphorus in the form of phosphate, and indicates the mass concentration of phosphorus present as phosphate ions. The temperature at which the liquid is brought into contact with the phosphorus-containing liquid (i.e., the liquid temperature of the liquid) is also not particularly limited, as long as the liquid state is maintained.

[0044] The amount of the ion adsorbent of the present disclosure used in a liquid containing phosphorus is not particularly limited, and can be determined appropriately depending on the concentration of phosphorus, etc.

[0045] As described above, the phosphorus adsorbent containing the foam glass composite material of the present disclosure can be applied to, for example, wastewater treatment devices. Specific examples of the wastewater treatment devices include collective wastewater (sewage) treatment facilities and decentralized wastewater treatment devices. Therefore, the present disclosure also encompasses a phosphorus removal method comprising a step of adsorbing and removing phosphorus in a collective wastewater (sewage) treatment facility or a decentralized wastewater treatment device using the phosphorus adsorbent. Examples of collective wastewater (sewage) treatment facilities include sewage treatment plants, agricultural wastewater treatment facilities, and sewage treatment plants. Decentralized wastewater treatment (also referred to as individual decentralized wastewater treatment) refers to treatment at the source of wastewater. Decentralized wastewater treatment devices refer to devices used in decentralized wastewater treatment, such as septic tanks, septic tanks, small-scale business wastewater treatment devices, and vegetation purification devices. The phosphorus adsorbent of the present disclosure is inexpensive and requires little maintenance, making it suitable for decentralized wastewater treatment devices.

[0046] After use in the adsorption method of the present disclosure, the adsorbed phosphorus can be desorbed by physical or chemical treatment. Examples of physical treatment include ultrasonic waves, heating, applied voltage, air pressure or water pressure control. Examples of chemical treatment include pH control using an acid or alkali. The desorbed phosphorus component can be separated from the phosphorus adsorbent and recovered. The phosphorus adsorbent from which the phosphorus component has been separated can also be reused. Alternatively, the adsorbent with adsorbed phosphorus can be used as fertilizer as is.

[0047] The present disclosure will be explained in more detail below using examples, but the technical scope of the present disclosure is not limited to these examples.

[0048] Experimental Example 1 (Composition of Foam Glass) The chemical composition of the foam glass raw material was determined. The chemical composition of the two types of foam glass shown below, which were crushed in an agate mortar, was determined using a wavelength dispersive small-sized X-ray fluorescence analyzer (Supermini 200, manufactured by Rigaku Corporation). The results are shown in Table 1. - Foam Glass 1 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass (particle diameter: approximately 2 to 10 mm) made primarily of clear glass, crushed in an agate mortar) - Foam Glass 2 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass (particle diameter: approximately 2 to 10 mm) made primarily of colored glass, crushed in an agate mortar)

[0049]

[0050] <Results> From Table 1, it was found that the main component of foam glasses 1 and 2 was soda glass, and that the contents of sodium and silicon were high.

[0051] Experimental Example 2 (Evaluation of phosphorus adsorption capacity of foam glass alone) In a 50 mL centrifuge tube, 1.5 g of foam glass 3 (trade name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass mainly made of colored glass (particle diameter: about 2 to 10 mm), specific gravity: 0.35 to 0.5) or 2 g of foam glass 4 (trade name Supersol (registered trademark) L4, manufactured by Kokko Co., Ltd., particle diameter: about 2 to 10 mm, specific gravity: 1.0 to 1.6) was added, and 50 mL of 10 mg-P / L phosphate phosphorus standard solution was added and shaken at 100 rpm and 25 ° C. for 24 hours in a shaker (manufactured by Tokyo Rikakikai Co., Ltd., LTE-1010) in an incubator (manufactured by Tokyo Rikakikai Co., Ltd., MMS-1020). Then, filtered with a syringe filter (manufactured by Milipore, SLHN033NB) having a pore size of 0.45 μm. The concentration of phosphate phosphorus in the filtrate was determined by measuring the absorbance at 880 nm by molybdenum blue absorptiometry using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600), and the adsorption rate was calculated using the following formula. The adsorption test was performed in triplicate.

[0052] The pH at the end of the experiment was measured using a pH meter (HORIBA Compact pH Meter LAQUAtwin pH-33B, manufactured by HORIBA Ltd.). The results are shown in Table 2.

[0053]

[0054] <Results> Table 2 shows that Foam Glass 3 and 4 have almost no ability to adsorb phosphate-phosphorus. Furthermore, the pH at the end of the experiment shifted to the alkaline side, from 8.30 to 10.2. Foam Glass 3 exceeded the septic tank discharge standard (pH 5.8 to 8.6).

[0055] Experimental Example 3 (Selection of Supported Elements for Foam Glass) As in Experimental Example 2, foam glass 3 (trade name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass mainly made of colored glass (particle diameter: about 2 to 10 mm), specific gravity: 0.35 to 0.5) and foam glass 4 (trade name Supersol (registered trademark) L4, manufactured by Kokko Co., Ltd., particle diameter: about 2 to 10 mm, specific gravity: 1.0 to 1.6) were used. (3-1) Preparation of Various Metal-Supported Foam Glasses Lanthanum chloride heptahydrate, iron (II) chloride tetrahydrate, and zirconium oxide chloride octahydrate were dissolved in pure water to prepare metal solutions so that the theoretical supported rates of lanthanum, iron, and zirconium were 1% by mass relative to the mass of foam glass 3 or foam glass 4. Next, 8 g of the foam glass 3 or foam glass 4 was weighed out into a disposable cup, the above-mentioned metal solution was added, and pure water was added until all particles of the foam glass 3 or foam glass 4 were immersed, and the mixture was left to stand for one day to support the metals. Thereafter, the foam glass 3 or foam glass 4 supporting various metals was dried at 100° C. for 10 hours in a dryer (DO-300FA, manufactured by AS ONE Corporation).

[0056] (3-2) Pre-test of phosphorus adsorption experiment (selection of supported metals) 1.5 g of foam glass 3 or 2 g of foam glass 4 supporting various metals listed in Table 3 below was placed in a 50 mL centrifuge tube, and 50 mL of a 10 mg-P / L phosphate phosphorus standard solution was added and shaken at 100 rpm and 25 ° C. for 24 hours in an incubator (Tokyo Rikakikai Co., Ltd., LTE-1010) using a shaker (Tokyo Rikakikai Co., Ltd., MMS-1020). Then, filtered with a syringe filter (Milipore, SLHN033NB) having a pore size of 0.45 μm. The phosphate phosphorus concentration of the filtrate was measured by molybdenum blue absorbance at 880 nm using a UV-visible spectrophotometer (Shimadzu Corporation, UV-2600) and the adsorption rate was calculated in the same manner as above. The results are shown in Table 3.

[0057]

[0058] <Results> Table 3 shows that, among lanthanum, iron, and zirconium, lanthanum had the highest phosphate-phosphorus adsorption rate. Based on these results, the following experiment was conducted using foam glass 3 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass made primarily from colored glass (particle diameter: approximately 2 to 10 mm), specific gravity: 0.35 to 0.5), which is widely available, and lanthanum and iron were used as the metals supported on the foam glass.

[0059] Experimental Example 4 (Study of lanthanum loading rate in foam glass) (4-1) Lanthanum loading in foam glass Lanthanum chloride heptahydrate was weighed out so that the theoretical loading rate was 0.01 mass%, 0.05 mass%, 0.1 mass%, 0.5 mass%, 1.0 mass%, 1.5 mass%, 2.0 mass%, 2.5 mass%, 3.0 mass%, or 3.5 mass%, and dissolved in pure water to prepare a lanthanum solution. Next, 8 g of foam glass 3 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass (particle diameter: approximately 2 to 10 mm), specific gravity: 0.35 to 0.5) was weighed into a disposable cup, and the lanthanum solution was added. Pure water was added until the entire particles of the foam glass 3 were immersed, and the mixture was left to stand for 1 day to load lanthanum. Thereafter, the lanthanum-supported foam glass 3 was dried at 100° C. for 10 hours in a dryer (DO-300FA, manufactured by AS ONE Corporation).

[0060] (4-2) Phosphorus Adsorption Experiment 0.5 g of lanthanum-supported foam glass 3 was placed in a 50 mL centrifuge tube, and 50 mL of a 10 mg-P / L phosphate-phosphorus solution was added. The mixture was shaken in an incubator at 100 rpm and 25 ° C. for 3 hours. The phosphate-phosphorus solution was then filtered using a syringe filter (Milipore, SLHN033NB) with a pore size of 0.45 μm. The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600), measuring the absorbance at 880 nm, and the adsorption rate was calculated in the same manner as above. The results are shown in Table 4 and FIG. 1. FIG. 1 is a graph showing the relationship between the lanthanum loading rate (theoretical value) of foam glass 3 and the adsorption rate of phosphate-phosphorus.

[0061]

[0062] <Results> From Table 4 and FIG. 1, it can be seen that the phosphorus adsorption rate increased to 90% when the lanthanum loading rate was 2% by mass.

[0063] Experimental Example 5 (Study on the calcination temperature of lanthanum-loaded foam glass) (5-1) Loading and calcination of lanthanum on foam glass Lanthanum chloride heptahydrate was weighed out so that the theoretical loading rate was 3.5% by mass and dissolved in pure water to prepare a lanthanum solution. Next, 8 g of foam glass 3 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass made primarily from colored glass (particle diameter: approximately 2 to 10 mm), specific gravity: 0.35 to 0.5) was weighed into a 50 mL centrifuge tube, and the lanthanum solution was added. Pure water was then added until the entire particles of foam glass 3 were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25 ° C., and lanthanum was loaded for 1 day. The mixture was then transferred to a disposable cup and dried in a dryer (DO-300FA, manufactured by AS ONE Corporation) at 100 ° C. for 10 hours. Next, the lanthanum-supported foam glass 3 was fired for 2 hours at 250°C, 350°C, 450°C, 550°C, 650°C, or 750°C using a gas replacement electric furnace (HPM-0G, manufactured by AS ONE Corporation), and then allowed to cool naturally.

[0064] (5-2) Phosphorus Adsorption Experiment 0.5 g of each calcined lanthanum-supported foam glass 3 was placed in a 50 mL centrifuge tube, and 50 mL of a 10 mg-P / L phosphate-phosphorus solution was added. The mixture was shaken in an incubator at 100 rpm and 25 °C for 3 hours. The phosphate-phosphorus solution was then filtered using a syringe filter (Milipore, SLHN033NB) with a pore size of 0.45 μm. The same operation as above was also performed on uncalcined lanthanum-supported foam glass 3. The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600), measuring the absorbance at 880 nm, and the adsorption rate was calculated in the same manner as above. The results are shown in Table 5 and Figure 2. Figure 2 shows the results of the adsorption rate of phosphate-phosphorus when the calcination temperature was changed at an initial phosphate-phosphorus concentration of 10 mg-P / L.

[0065]

[0066] <Results> As can be seen from Table 5 and Figure 2, Reference Example 17, which was not fired, had a phosphate-phosphorus adsorption rate close to 100%, but lanthanum peeled off. When fired at temperatures of 250 to 750°C, the resulting foam glass composite material was able to adsorb phosphate-phosphorus without lanthanum peeling. In particular, when fired at temperatures up to 350°C, the phosphate-phosphorus adsorption rate was nearly 100%. Therefore, the following experiment was conducted at a firing temperature of 350°C, at which lanthanum did not peel off and the phosphate-phosphorus adsorption rate was high.

[0067] Experimental Example 6 (Study of iron loading rate in foam glass) (6-1) Loading and calcination of iron and lanthanum on foam glass Iron (II) chloride tetrahydrate was weighed out so that the theoretical loading rate was 0.005 mass%, 0.01 mass%, 0.015 mass%, 0.02 mass%, 0.025 mass%, 0.05 mass%, 0.075 mass%, 0.1 mass%, 0.25 mass%, or 0.5 mass%, and dissolved in pure water to prepare an iron solution. Next, 8 g of foam glass 3 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass mainly made of colored glass (particle diameter: about 2 to 10 mm), specific gravity: 0.35 to 0.5) was weighed into a 50 mL centrifuge tube, and the iron solution was added. Pure water was then added until the entire particles of foam glass 3 were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25 ° C., and iron was allowed to be loaded for 1 day. The tube was then transferred to a disposable cup and dried in a dryer (DO-300FA, manufactured by AS ONE Corporation) at 100 ° C. for 10 hours. Lanthanum was loaded onto the resulting 10 types of iron-loaded foam glass 3 and iron-free foam glass 3 using the following procedure. Lanthanum chloride heptahydrate was weighed out so that the theoretical loading rate was 3.5% by mass, and dissolved in pure water to prepare a lanthanum solution. Next, 8 g of each iron-loaded foam glass 3 or iron-free foam glass 3 was weighed into a 50 mL centrifuge tube, and the lanthanum solution was added. Pure water was then added until the entire particles of the foam glass 3 were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25 ° C., and lanthanum was allowed to be loaded for 1 day. Thereafter, the mixture was transferred to a disposable cup and dried in a dryer (DO-300FA, manufactured by AS ONE Corporation) at 100° C. for 10 hours. Next, the iron-lanthanum-supported foamed glass 3 was fired at 350° C. for 2 hours using a gas-substituted electric furnace (HPM-0G, manufactured by AS ONE Corporation).

[0068] (6-2) Phosphorus Adsorption Experiment 0.5 g of iron-lanthanum-supported foam glass 3 or lanthanum-supported foam glass 3 with a theoretical iron loading rate of 0.005 to 0.1% by mass was placed in a 50 mL centrifuge tube, and 50 mL of a 10 mg-P / L phosphate-phosphorus solution was added. The mixture was then shaken in an incubator at 100 rpm and 25 °C for 3 hours. The phosphate-phosphorus solution was then filtered using a syringe filter (Milipore, SLHN033NB) with a pore size of 0.45 μm. The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600) to measure the absorbance at 880 nm, and the adsorption rate was calculated in the same manner as above. The results are shown in Table 6. A graph showing the relationship between iron loading rate and phosphate-phosphorus adsorption rate is shown in Figure 3. 1.5 g of iron-lanthanum-supported foam glass 3 or lanthanum-supported foam glass 3 with a theoretical loading rate of 0.1 to 0.5% by mass was placed in a 50 mL centrifuge tube, and 50 mL of a 100 mg-P / L phosphate-phosphorus solution was added. The mixture was shaken in an incubator at 100 rpm and 25 ° C. for 3 hours. The phosphate-phosphorus solution was then filtered using a syringe filter (Milipore, SLHN033NB) with a pore size of 0.45 μm. The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600), measuring the absorbance at 880 nm, and the adsorption rate was calculated in the same manner as above. The results are shown in Table 7. Graphs showing the relationship between iron loading rate and phosphate-phosphorus adsorption rate are shown in FIG. 4.

[0069] (6-3) Absorbance Measurement 50 mL of the above 100 mg-P / L phosphate solution was added, and the unfiltered sample was shaken in an incubator for 3 hours. The absorbance at a wavelength of 660 nm was measured and used as an index of turbidity. The results are shown in Table 7. A graph showing the relationship between iron loading and absorbance at a wavelength of 660 nm is shown in Figure 5.

[0070] (6-4) BET Specific Surface Area Measurement Furthermore, in order to confirm how the specific surface area of ​​the foam glass changes when the iron loading rate is changed, iron (II) chloride tetrahydrate was weighed out so that the theoretical loading rate was 0.1 mass%, 0.25 mass%, 1 mass%, or 2 mass%, and dissolved in pure water to prepare an iron solution. Pure water was then added until the entire particles of foam glass 3 were immersed. Thereafter, the centrifuge tube was shaken in an incubator at 100 rpm and 25 ° C., and iron was loaded for 1 day. Thereafter, the sample was transferred to a disposable cup and dried at 100 ° C. for 10 hours in a dryer (manufactured by AS ONE Corporation, DO-300FA) to prepare iron-loaded foam glass 3. The sample was then pulverized in an agate mortar and subjected to BET specific surface area measurement by nitrogen gas adsorption using a specific surface area measurement device (manufactured by micromeritics, FlowSorb III). The BET specific surface area was also measured for the foam glass 3 that did not support iron. The results are shown in Table 8 and FIG.

[0071]

[0072]

[0073]

[0074] <Results> Tables 6 and 7, as well as Figures 3 and 4, show the results of the phosphate-phosphorus adsorption rate when the iron loading rate was changed between 0 and 0.5% by mass. Table 6 and Figure 3 show that when the initial phosphate-phosphorus concentration was 10 mg-P / L, the phosphate-phosphorus adsorption rate was high, ranging from 89.3% to 99.9%, regardless of the iron loading rate. Table 7 and Figure 4 show that when the initial phosphate-phosphorus concentration was 100 mg-P / L, the phosphate-phosphorus adsorption rate tended to be highest when the iron loading rate was 0.1% by mass. The turbidity in Table 7 and Figure 5 show that when the initial phosphate-phosphorus concentration was 100 mg-P / L, the absorbance (turbidity) at 660 nm increased when the iron loading rate was 0.25% by mass or higher. This is thought to be due to the generation of rust-like suspended matter when the iron loading rate was 0.25% by mass or higher. Furthermore, Table 8 and Figure 6 show that the BET specific surface area of ​​foam glass 3 was 0.043 m ２ / g, but by supporting 0.1 mass % of iron, ２ / g. This indicates that supporting iron is effective for increasing the specific surface area of ​​foam glass. Based on the above results, the following experiment was carried out with the iron supporting rate set to 0.1 mass %.

[0075] Experimental Example 7 (Investigation of Lanthanum Loading Rate in Iron-Loaded Foam Glass) (7-1) Loading and Calcination of Iron and Lanthanum on Foam Glass Iron (II) chloride tetrahydrate was weighed out so that the theoretical loading rate was 0.1% by mass and dissolved in pure water to prepare an iron solution. Next, 8 g of foam glass 3 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass made primarily from colored glass (particle diameter: approximately 2 to 10 mm), specific gravity: 0.35 to 0.5) was weighed into a 50 mL centrifuge tube, and the iron solution was added. Pure water was then added until the entire particles of foam glass 3 were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25 ° C., and the iron was allowed to load for 1 day. The mixture was then transferred to a disposable cup and dried at 100 ° C. for 10 hours in a dryer (DO-300FA, manufactured by AS ONE Corporation). Lanthanum was loaded onto this iron-loaded foam glass 3 by the following procedure. Lanthanum chloride heptahydrate was weighed out so that the theoretical loading rate was 0.5% by mass, 1% by mass, 1.5% by mass, 2% by mass, 2.5% by mass, 3% by mass, or 3.5% by mass, and dissolved in pure water to prepare a lanthanum solution. Next, 8 g of iron-loaded foam glass 3 was weighed into a 50 mL centrifuge tube, the lanthanum solution was added, and pure water was added until all of the particles of foam glass 3 were immersed. Thereafter, the centrifuge tube was shaken in an incubator at 100 rpm and 25 ° C., and lanthanum was loaded for 1 day. Thereafter, the mixture was transferred to a disposable cup and dried at 100 ° C. for 10 hours in a dryer (DO-300FA, manufactured by AS ONE Corporation). Next, the iron-lanthanum-loaded foam glass 3 was fired at 350 ° C. for 2 hours using a gas-substituted electric furnace (HPM-0G, manufactured by AS ONE Corporation).

[0076] (7-2) Phosphorus Adsorption Experiment 0.5 g of iron-lanthanum-supported foam glass 3 was placed in a 50 mL centrifuge tube, and 50 mL of a 10 mg-P / L phosphate-phosphorus solution was added. The mixture was shaken at 100 rpm and 25 ° C. for 3 hours using a shaker (Tokyo Rikakikai Co., Ltd., MMS-1020) in an incubator. The phosphate-phosphorus solution was then filtered using a syringe filter (Milipore, SLHN033NB) with a pore size of 0.45 μm. The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600) to measure the absorbance at 880 nm, and the adsorption rate was calculated in the same manner as above. The results are shown in Table 9. A graph showing the relationship between lanthanum loading rate and phosphate-phosphorus adsorption rate is shown in FIG. 7.

[0077]

[0078] <Results> The following shows the results of the adsorption rate of phosphorus phosphate when the iron loading rate was 0.1 mass% and the lanthanum loading rate was changed. From Table 9 and Figure 7, it was found that the adsorption rate of phosphorus phosphate reached 94.6% when the lanthanum loading rate was 2 mass%. Therefore, the following experiment was performed with the iron loading rate of 0.1 mass% and the lanthanum loading rate of 2 mass%.

[0079] Experimental Example 8 (Adsorption Rate and Adsorption Isotherm) (8-1) Supporting and Calcining of Iron and Lanthanum on Foam Glass Iron (II) chloride tetrahydrate was weighed out so that the theoretical loading rate was 0.1% by mass and dissolved in pure water to prepare an iron solution. Next, 8 g of foam glass 3 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass made primarily from colored glass (particle diameter: approximately 2 to 10 mm), specific gravity: 0.35 to 0.5) was weighed into a 50 mL centrifuge tube, and the above-mentioned iron solution was added. Pure water was then added until the entire particles of foam glass 3 were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25°C, and iron was allowed to be supported for 1 day. The mixture was then transferred to a disposable cup and dried in a dryer (DO-300FA, manufactured by AS ONE Corporation) at 100°C for 10 hours. Lanthanum was supported on this iron-supported foam glass 3 using the following procedure. Lanthanum chloride heptahydrate was weighed out so that the theoretical loading rate was 2% by mass, and dissolved in pure water to prepare a lanthanum solution. Next, 8 g of iron-supported foam glass 3 was weighed into a 50 mL centrifuge tube, the above-mentioned lanthanum solution was added, and pure water was added until all of the particles of foam glass 3 were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25 ° C., and lanthanum was supported for 1 day. Thereafter, it was transferred to a disposable cup and dried at 100 ° C. for 10 hours in a dryer (manufactured by AS ONE Corporation, DO-300FA). Next, the iron-lanthanum-supported foam glass 3 was fired at 350 ° C. for 2 hours using a gas-substituted electric furnace (manufactured by AS ONE Corporation, HPM-0G).

[0080] (8-2) Phosphorus adsorption experiment 1 g of the obtained iron-lanthanum-supported foam glass 3 was placed in a 500 mL Erlenmeyer flask. Next, 500 mL of 1 mg-P / L or 10 mg-P / L phosphate-phosphorus solution was added and shaken in an incubator at 100 rpm and 25 ° C., and 5 mL of the solution was collected at predetermined intervals. The phosphate-phosphorus solution was filtered using a syringe filter (Milipore, SLHN033NB) with a pore size of 0.45 μm. The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2600) to measure the absorbance at 880 nm, and the phosphate adsorption amount was calculated using the following formula.

[0081] <Phosphate adsorption amount> q = Sｒｅｍ (C ｃｏｎ -C ｓａｍ ) / (1000·a) q: Phosphate-phosphorus adsorption amount (mg-P / g) S ｒｅｍ : remaining amount of solution (mL) C ｃｏｎ : Control concentration (mg-P / L) C ｓａｍ : sample concentration (mg-P / L) a: adsorbent dosage (g) The unit of adsorption amount (mg-P / g) is the amount of phosphate phosphorus, and indicates the mass of phosphorus present as phosphate ions. The results when the initial phosphate phosphorus concentration was 1 mg-P / g are shown in Table 10 and Figure 8, and the results when the initial phosphate phosphorus concentration was 10 mg-P / g are shown in Table 11 and Figure 9.

[0082]

[0083]

[0084] <Results> Figures 8 and 9 are graphs showing the change over time in the amount of adsorption of phosphate-phosphorus of foam glass 3 supporting 0.1 mass% iron and 2 mass% lanthanum and fired at 350 ° C. for 2 hours. As shown in Table 10 and Figure 8, when the initial phosphate-phosphorus concentration was 1 mg-P / L, the amount of adsorption reached equilibrium 48 hours after the start of shaking, and the equilibrium adsorption amount was 0.37 mg-P / g. As shown in Table 11 and Figure 9, when the initial phosphate-phosphorus concentration was 10 mg-P / L, the amount of adsorption reached equilibrium 48 hours after the start of shaking, and the equilibrium adsorption amount was 1.44 mg-P / g.

[0085] (8-3) Adsorption Isotherm 1 g of iron-lanthanum-supported foam glass 3 was placed in a 500 mL Erlenmeyer flask. Next, 500 mL of phosphate-phosphorus solution of 1 mg-P / L, 2 mg-P / L, 5 mg-P / L, 10 mg-P / L, 20 mg-P / L, 40 mg-P / L, or 100 mg-P / L was added and shaken at 100 rpm and 25 ° C. in an incubator. After 48 hours, 5 mL of the solution was collected, and the phosphate-phosphorus solution was filtered using a syringe filter (manufactured by Milipore, SLHN033NB) with a pore size of 0.45 μm. The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-2600) to measure the absorbance at 880 nm, and the equilibrium adsorption amount was calculated in the same manner as above. The results are shown in Table 12 and FIG.

[0086]

[0087] <Results> Figure 10 shows the adsorption isotherm for the iron-lanthanum-supported foam glass composite material. The adsorption isotherm shown in Figure 10 is of the Langmuir type. Table 12 shows that the saturated adsorption amount was 1.24 mg-P / g.

[0088] Experimental Example 9 (Adsorption Experiment Using Actual Wastewater) (9-1) Supporting and Firing of Iron and Lanthanum on Foam Glass Foam glass was used (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass made primarily of colored glass (particle diameter: approximately 10 to 20 mm), specific gravity: 0.35 to 0.5). Foam glass 5 was obtained by using a sieve to select foam glass 3 (product name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass made primarily of colored glass (particle diameter: approximately 2 to 10 mm), specific gravity: 0.35 to 0.5) with a particle diameter of approximately 10 to 20 mm. Iron (II) chloride tetrahydrate was weighed out so that the theoretical support rate was 0.1% by mass and dissolved in pure water to prepare an iron solution. Next, 2 L (460 g to 463 g) of the foam glass 5 was weighed into a 2 L polypropylene (PP) bottle (I-Boy wide-mouth bottle, manufactured by AS ONE Corporation), the iron solution was added, and pure water was added until all of the particles of the foam glass 5 were immersed. The container containing the foam glass 5 and the iron solution was then reciprocally shaken horizontally in a shaker (Shaker (SA300), manufactured by Yamato Scientific Co., Ltd.) at 25 ° C. for 18 hours or more to support the iron. The container was then dried at 100 ° C. for 18 hours or more in a dryer (constant temperature dryer DX41, manufactured by Yamato Scientific Co., Ltd.). Lanthanum was supported on this iron-supported foam glass 5 using the following procedure. Lanthanum chloride heptahydrate was weighed out so that the theoretical support rate was 3.5 mass % and dissolved in pure water to prepare a lanthanum solution. Next, 2 L of the iron-supported foam glass 5 was measured out and placed in a 2 L polypropylene (PP) bottle (manufactured by AS ONE Corporation, I-Boy wide-mouth bottle), and the above-mentioned lanthanum solution was added, followed by pure water until all of the particles of the foam glass 5 were immersed. Thereafter, the container containing the iron-supported foam glass 5 and the lanthanum solution was shaken back and forth horizontally in a shaker (manufactured by Yamato Scientific Co., Ltd., Shaker (SA300)) at 25 ° C. for 18 hours or more to support the lanthanum. Thereafter, it was dried at 100 ° C. for 18 hours or more in a dryer (manufactured by Yamato Scientific Co., Ltd., constant temperature dryer DX41). Next, the iron-lanthanum-supported foam glass 5 was fired at 350 ° C. for 2 hours using an electric furnace (manufactured by Yamato Scientific Co., Ltd., FO810).

[0089] (9-2) Measurement of Phosphorus Adsorption Rate Using Actual Wastewater Using the prepared iron-lanthanum-supported foam glass 5, the phosphorus adsorption rate was measured using the phosphorus removal device shown in FIG. 11. The phosphorus removal device was a device at 1 / 1000 the scale of an actual septic tank. The operating conditions are shown in Table 13 below. The composition of the septic tank wastewater, which was the raw water, is shown in Table 14 below. Three types of wastewater with different initial phosphate-phosphorus concentrations were used (wastewater 1: wastewater with an initial phosphate-phosphorus concentration of 5 mg-P / L, wastewater 2: wastewater with an initial phosphate-phosphorus concentration of 15 mg-P / L, and wastewater 3: wastewater with an initial phosphate-phosphorus concentration of 50 mg-P / L).

[0090]

[0091]

[0092] BOD stands for Biochemical Oxygen Demand. d-BOD stands for soluble BOD, and components that pass through a filter with a pore size of 0.45 to 1 μm are generally called "soluble." ATU-BOD is the BOD measured after adding a nitrification inhibitor (allylthiourea (ATU)). COD stands for Chemical Oxygen Demand. TN stands for total nitrogen. NH ４ -N refers to ammonia nitrogen. ４ -P refers to phosphate phosphorus. TP refers to total phosphorus.

[0093] The prepared iron-lanthanum-supported foam glass 5 (Example) or foam glass 5 (Comparative Example) was filled into the phosphorus removal device shown in Figure 11, and the wastewaters 1 to 3 were treated at 20°C for 24 hours. Iron-lanthanum-supported foam glass 5 or foam glass 5 was filled into the phosphorus removal device, and sampling was performed before operating the pump (0 hours), and 0.5 hours, 1 hour, 2 hours, 4 hours, 8 hours, and 24 hours after operating the pump, and the phosphate concentration in the wastewater was measured by molybdenum blue absorptiometry. The results are shown in Tables 15 to 17 and Figures 12 to 14.

[0094]

[0095]

[0096]

[0097] <Results> Tables 15 to 17 and Figures 12 to 14 show that the iron-lanthanum-supported foam glass composite material has the ability to remove phosphorus, even in actual wastewater, without being affected by other ions. This application claims priority from Japanese Patent Application No. 2023-173693, filed October 5, 2023. Japanese Patent Application No. 2023-173693 is incorporated herein by reference.

[0098] The foam glass composite material of the present disclosure has a high phosphorus adsorption rate and is therefore useful as a phosphorus adsorbent for removing phosphorus from water.

Claims

1. A foam glass composite material containing foam glass, iron or its compounds, and lanthanum or its compounds.

2. The foam glass composite material according to claim 1, wherein the content of the lanthanum or a compound thereof is 0.01% by mass or more.

3. The foam glass composite material according to claim 1, wherein the content of the iron or its compound is 0.005 mass% or more.

4. The foam glass composite material according to claim 1, wherein the average particle size of the foam glass is 75 mm or less.

5. The foam glass composite material according to claim 1, obtained by firing foam glass, iron or a compound thereof, and lanthanum or a compound thereof at 700°C or less.

6. The foam glass composite material according to claim 1, which is used to remove phosphorus contained in wastewater.

7. A method for producing the foam glass composite material of claim 1, comprising the step of mixing foam glass with iron or a compound thereof and lanthanum or a compound thereof.

8. The method for producing a foam glass composite material according to claim 7, wherein the step of mixing the foam glass with iron or a compound thereof and lanthanum or a compound thereof comprises: a step of supporting iron or a compound thereof on the foam glass to obtain an iron-supported foam glass composite material; and a step of supporting lanthanum or a compound thereof on the iron-supported foam glass composite material to obtain an iron-lanthanum-supported foam glass composite material.

9. The method for producing a foam glass composite material according to claim 8, further comprising a step of firing the iron-lanthanum-loaded foam glass composite material at 700° C. or less.

10. A phosphorus adsorbent comprising the foam glass composite material according to any one of claims 1 to 6.

11. A wastewater treatment device comprising the phosphorus adsorbent according to claim 10.

12. A method for adsorbing phosphorus, comprising contacting the phosphorus adsorbent according to claim 10 with a liquid containing phosphorus.

13. A method for removing phosphorus, comprising adsorbing and removing phosphorus from wastewater using the phosphorus adsorbent according to claim 10.

14. A method for using a foam glass composite material containing foam glass, iron or a compound thereof, and lanthanum or a compound thereof for adsorbing and removing phosphorus from wastewater.

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