Foam Glass Composite

Abstract

To provide a novel foamed glass composite material capable of removing environmental pollutants such as phosphorus.SOLUTION: 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 the foamed glass composite material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to foam glass composite materials. [Background technology]

[0002] Wastewater from industries, households, and agricultural areas contains nutrients such as nitrogen and phosphorus that cause eutrophication. When this wastewater flows into rivers, lakes, and oceans, it is known to cause large-scale outbreaks of red tides and blue-green algae. 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 2017), and in areas without sewerage systems, such as suburban areas and depopulated areas, septic tanks are installed as wastewater treatment systems. Ordinary septic tanks do not have the ability to remove nitrogen and phosphorus. As a result, the achievement rate for total nitrogen and total phosphorus in lakes and ponds (FY2015) was a low 51.2%. Therefore, even in septic tanks installed in areas without sewer systems, advanced treatment to remove nitrogen and phosphorus is required.

[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) that 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 Law for Promoting Effective Utilization of Resources was enacted in 2001, and efforts to promote the 3Rs of reduce, reuse, and recycle are being promoted in the glass industry as well. 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 being collected sufficiently, and most of them are being disposed of in landfills, causing 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] In recent years, a method has been proposed to solve the above problems by utilizing waste glass to remove water pollutants such as phosphorus. For example, Patent Document 1 proposes a phosphate ion adsorbent containing foamed glass made from waste glass. Patent Document 1 describes adding a material containing at least one of calcium, magnesium, and iron to the foamed glass, but does not describe 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 describe or suggest supporting lanthanum. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-161398 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-192977 Summary of the Invention [Problem to be solved by the invention]

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

[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 invention was completed based on this finding.

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

[0011] According to the present invention, 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 invention has excellent ability to adsorb water pollutants, particularly phosphorus, and is therefore useful as a phosphorus adsorbent. [Brief explanation of the drawings]

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

[0013] 1.Foam glass composite material The foam glass composite material of the present invention contains foam glass, iron or a compound thereof, and lanthanum or a compound thereof. The foam glass composite material of the present invention can also be called an iron-lanthanum-supported foam glass composite material in which iron or a compound thereof and lanthanum or a compound thereof are supported on foam glass. The foam glass composite material of the present invention has iron or a compound thereof and lanthanum or a compound thereof supported on the surface of porous foam glass, and since the iron or a compound thereof and the lanthanum or a compound thereof adsorb water pollutants such as phosphorus, water pollutants such as phosphorus can be removed.

[0014] foam glass Foam glass is glass having many pores. Foam glass can be produced by a known method. For example, foam glass 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 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 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, it is preferable to perform particle size classification 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 pulverized glass and a foaming agent are mixed. The type of foaming agent is not particularly limited, and examples thereof include materials (such as seashells) containing silicon carbide (SiC), silicon nitride (SiN), calcium carbonate (CaCO3), dolomite (CaMg(CO3)2), magnesium carbonate (MgCO3), etc. 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% based on the raw glass (see JP 2011-161398 A). Using the foaming agent in this range ensures sufficient foaming and prevents excessive foaming, which can lead to a decrease in the strength of the foamed glass. When mixing the pulverized glass and the foaming agent, a material containing at least one of calcium, magnesium, and 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 in 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 form pores appropriately, and the glass does not become too soft, so that the formed pores can be prevented from being closed again. The firing time is, for example, 1 to 60 minutes, preferably 5 to 10 minutes. If the firing time is within this range, foaming occurs sufficiently and it is possible to prevent the formed pores from being closed again or the bubbles from sticking together, resulting in a loss of surface fineness (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 compounds The iron or its compound contained in the foam glass composite material of the present invention is not particularly limited as long as it contains iron, and may be, for example, an iron atom (Fe), an iron ion (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 (Fe3O4), and iron (III) oxide (Fe2O3). Examples of iron hydroxides contained in foam glass composite materials include goethite (FeO(OH)), iron(II) hydroxide (Fe(OH)2), and 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 phosphate (III) (FePO4). Examples of water-soluble iron compounds contained in the foam glass composite material include iron(II) chloride (FeCl2), iron(III) chloride (FeCl3), iron(II) nitrate (Fe(NO3)2), iron(III) nitrate (Fe(NO3)3), iron(II) sulfate (FeSO4), iron(III) sulfate (Fe2(SO4)3), iron(II) acetate (Fe(CH3CO2)2), and 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 inside the foam glass. The content of iron or a compound thereof 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 the foam glass. That is, the content of iron or a compound thereof in the foamed glass composite material is preferably 0.005 mass % or more, more preferably 0.01 mass % or more, still more preferably 0.05 to 0.5 mass %, and particularly preferably 0.1 to 0.25 mass %.

[0023] Lanthanum or its compounds The lanthanum or a compound thereof contained in the foamed glass composite material of the present invention 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), lanthanum nitrate (La(NO)), lanthanum sulfate (La(SO), lanthanum acetate (La(CHCO)), and hydrates thereof.

[0024] The lanthanum content in the foam glass composite material can be measured, for example, by fluorescent X-ray analysis. The lanthanum content in the foam glass composite material means the loading rate of lanthanum (metal) by mass, and is a theoretical value. The content of lanthanum or a compound thereof in the foam glass composite material is preferably 0.01 part 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 the foam glass. That is, the content of lanthanum or a compound thereof in the foam glass composite material is preferably 0.01 mass % or more, more preferably 0.5 to 3.5 mass %, and even more preferably 2 to 3.5 mass %. By setting the content of each component within the above range, 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 invention contains foam glass, iron or a compound thereof, and lanthanum or a compound thereof, but any material containing foam glass, iron or a compound thereof, and lanthanum or a compound thereof as raw materials may be used, 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 specify 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 / g or more, high phosphorus adsorption performance can be exhibited. The upper limit of the BET specific surface area is not particularly limited, but is preferably 20 m 2 / g.

[0027] The foamed 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 foamed 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 foamed glass composite material 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.

[0028] 2. Manufacturing method of foam glass composite material The method for producing a foam glass composite material of the present invention includes a step of mixing foam glass with iron or a compound thereof and lanthanum or a compound thereof. The method for producing the foam glass composite material is not particularly limited as long as the foam glass composite material containing foam glass, iron or a compound thereof, and lanthanum or a compound thereof can be obtained.

[0029] Examples of production methods 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 manufacturing 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 manufacturing 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 process 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 and drying the solution, and a method of spraying the iron aqueous solution onto the foam glass. Water-soluble iron compounds react as iron ions (Fe 2+ , Fe 3+ The water-soluble iron compound is not particularly limited as long as it releases iron. Examples of such water-soluble iron compounds include iron(II) chloride (FeCl2), iron(III) chloride (FeCl3), iron(II) nitrate (Fe(NO3)2), iron(III) nitrate (Fe(NO3)3), iron(II) sulfate (FeSO4), iron(III) sulfate (Fe2(SO4)3), iron(II) acetate (Fe(CH3CO2)2), and hydrates thereof. The concentration of the aqueous iron solution used may be appropriately adjusted so that the iron content in the final foam glass composite material is 0.005 parts by mass or more per 100 parts by mass of foam glass.

[0031] Examples of the process for loading lanthanum or a compound thereof onto the iron-loaded foam glass composite material include a method of immersing the iron-loaded 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 onto the iron-loaded foam glass composite material. As a water-soluble lanthanum compound, lanthanum ions (La 3+ The water-soluble lanthanum compound is not particularly limited as long as it releases lanthanum. Examples of such water-soluble lanthanum compounds include lanthanum chloride (LaCl), lanthanum nitrate (La(NO)), lanthanum sulfate (La(SO), lanthanum acetate (La(CHCO)), and hydrates thereof. 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 foam glass.

[0032] The amount of iron supported per 100 parts by mass of foamed 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 foamed 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 foam glass composite material thus obtained is preferably further dried and then fired. By drying the foam glass composite material and then firing it, the bond between the foam glass and lanthanum can be strengthened to prevent the lanthanum from peeling off, and the phosphorus adsorption performance of the foam glass composite material can be improved. 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 foamed glass, the drying temperature, etc., but basically, it is sufficient to set the time required to remove the moisture content. It is also preferable to perform drying in a highly breathable oven such as a hot air oven. The firing temperature is usually 750°C or lower, preferably 250 to 700°C, more preferably 260 to 400°C, further preferably 300 to 380°C, and particularly preferably 330 to 370°C, so that lanthanum and the like do not peel off and a high phosphorus adsorption rate is obtained.

[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 adjusted appropriately depending on the firing temperature, etc.

[0035] The obtained fired body may be further processed depending on the specific environment of use. 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 being subjected to treatment such as crushing and classification as necessary. The foam glass composite material of the present invention 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 invention exhibits excellent environmental purification activity. Specifically, the foam glass composite material of the present invention can be used as a material for removing water pollutants from water, such as removing phosphorus and arsenic from water. The foam glass composite material of the present invention can be used as a phosphorus adsorbent, particularly because it has excellent adsorption capacity for phosphorus (phosphate ions, phosphate phosphorus, dissolved inorganic phosphate, etc.) in wastewater.

[0036] 3. Phosphorus adsorbent The phosphorus adsorbent of the present invention includes the foam glass composite material described above, and therefore 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 1m 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 / g or more, high phosphorus adsorption performance can be exhibited. 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. 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 ions (PO4 3- ), dihydrogen phosphate ion (H2PO4 - ) and hydrogen phosphate ion (HPO4 2- ), as well as phosphite ions, polyphosphate ions, etc.

[0040] Although the phosphorus adsorption capacity of the phosphorus adsorbent of the present invention varies depending on the experimental conditions, for example, the phosphorus adsorption capacity 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 invention is approximately 1.6 to 6.6 mg / L / h (see Examples). As described above, the phosphorus adsorbent of the present invention has high phosphorus adsorption capacity (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 invention has high phosphorus adsorption capacity at phosphorus concentrations (1 to 5 mg / L) (low concentration range) such as those occurring in septic tank wastewater, and therefore can be applied to decentralized wastewater treatment devices, particularly septic tanks.

[0041] 4. Phosphorus adsorption method The present invention also encompasses a method for adsorbing phosphorus, 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 phosphorus, and dissolved inorganic phosphate.

[0042] In the adsorption method of the present invention, 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 phosphate phosphorus, which indicates the mass concentration of phosphorus present as phosphate ions. The temperature at which the phosphorus-containing liquid is brought into contact with the phosphorus-containing liquid (i.e., the liquid temperature of the liquid) is not particularly limited as long as the liquid state is maintained.

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

[0045] As described above, the phosphorus adsorbent containing the foam glass composite material of the present invention can be applied to, for example, wastewater treatment devices. Specific examples of such wastewater treatment devices include collective wastewater (sewage) treatment facilities and decentralized wastewater treatment devices. Therefore, the present invention 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 invention is inexpensive and requires little maintenance, making it suitable for decentralized wastewater treatment devices.

[0046] After use in the adsorption method of the present invention, the adsorbed phosphorus can be desorbed by physical or chemical treatment. Examples of physical treatment include ultrasonic waves, heating, applied voltage, and atmospheric 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 a fertilizer as is. [Example]

[0047] The present invention will be explained in more detail below with reference to examples, but the technical scope of the present invention 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, crushed in an agate mortar, was determined using a wavelength-dispersive compact X-ray fluorescence analyzer (Rigaku Corporation, Supermini200). 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 from transparent 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 from colored glass, crushed in an agate mortar)

[0049] [Table 1]

[0050] <Result> From Table 1, it can be seen that the main component of foam glasses 1 and 2 is soda glass, and that they contain high amounts of sodium and silicon.

[0051] Experimental Example 2 (Evaluation of phosphorus adsorption capacity of foam glass only) 1.5 g of foam glass 3 (trade name Supersol® L2, manufactured by Kokko Co., Ltd.; foam glass primarily made from colored glass (particle size: approximately 2-10 mm, specific gravity: 0.35-0.5) or 2 g of foam glass 4 (trade name Supersol® L4, manufactured by Kokko Co., Ltd.; particle size: approximately 2-10 mm, specific gravity: 1.0-1.6) was placed in a 50 mL centrifuge tube, 50 mL of 10 mg-P / L phosphate standard solution was added, and the mixture was shaken at 100 rpm at 25°C for 24 hours in a shaker (Tokyo Rikakikai Co., Ltd.; MMS-1020) in an incubator (Tokyo Rikakikai Co., Ltd.; LTE-1010). The mixture was then filtered through a 0.45 μm syringe filter (Milipore; SLHN033NB). The phosphate concentration of the filtrate was determined by measuring the absorbance at 880 nm using a molybdenum blue absorptiometry method with 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.

number

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

[0053] [Table 2]

[0054] <Result> 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, an experiment was conducted using foam glass 3 (trade 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) and foam glass 4 (trade name Supersol (registered trademark) L4, manufactured by Kokko Co., Ltd., particle diameter: approximately 2 to 10 mm, specific gravity: 1.0 to 1.6). (3-1) Preparation of various metal-loaded foam glass Lanthanum chloride heptahydrate, iron (II) chloride tetrahydrate, and zirconium oxide chloride octahydrate were dissolved in pure water to prepare metal solutions such that the theoretical loading 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 foam glass 3 or foam glass 4 was weighed into a disposable cup, the metal solution was added, and pure water was added until all the particles of foam glass 3 or foam glass 4 were immersed. The mixture was left to stand for one day to load the metals. Thereafter, foam glass 3 or foam glass 4 loaded with various metals was dried at 100°C for 10 hours in a dryer (DO-300FA, manufactured by AS ONE Corporation).

[0056] (3-2) Preliminary test for phosphorus adsorption experiment (selection of supported metal) 1.5 g of foam glass 3 carrying various metals listed in Table 3 below or 2 g of foam glass 4 carrying various metals was placed in a 50 mL centrifuge tube, 50 mL of 10 mg-P / L phosphate standard solution was added, and the mixture was shaken at 100 rpm and 25 ° C. for 24 hours in a shaker (Tokyo Rikakikai Co., Ltd., MMS-1020) in an incubator (Tokyo Rikakikai Co., Ltd., LTE-1010). Then, the mixture was filtered with a syringe filter (Milipore Co., Ltd., SLHN033NB) having a pore size of 0.45 μm. The phosphate concentration of the filtrate was determined by measuring the absorbance at 880 nm using a molybdenum blue absorptiometry method with an ultraviolet-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] [Table 3]

[0058] <Result> Table 3 shows that among lanthanum, iron, and zirconium, lanthanum had the highest adsorption rate of phosphate phosphorus. Based on these results, the following experiment was conducted using the widely distributed 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) as the foam glass, and using lanthanum and iron as the metals to be supported on the foam glass.

[0059] Experimental Example 4 (Study of lanthanum loading rate in foam glass) (4-1) Supporting lanthanum on foam glass Lanthanum chloride heptahydrate was weighed out to theoretical loading rates of 0.01%, 0.05%, 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, or 3.5% by mass and dissolved in pure water to prepare a lanthanum solution. Next, 8 g of foam glass 3 (trade name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass primarily made from colored 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 foam glass 3 particles were immersed, and the mixture was left to stand for one day to load lanthanum. The lanthanum-loaded foam glass 3 was then 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, followed by shaking in an incubator at 100 rpm and 25° C. for 3 hours. The phosphate-phosphorus solution was then filtered through a syringe filter with a pore size of 0.45 μm (Milipore Corporation, SLHN033NB). The phosphate concentration of 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 in the same manner as above. The results are shown in Table 4 and Figure 1. Figure 1 is a graph showing the relationship between the loading rate (theoretical value) of lanthanum loaded on foam glass 3 and the adsorption rate of phosphorus phosphate.

[0061] [Table 4]

[0062] <Result> As can be seen from Table 4 and FIG. 1, the phosphorus adsorption rate increased to 90% when the lanthanum loading rate was 2 mass %.

[0063] Experimental Example 5 (Investigation of the firing temperature of lanthanum-loaded foam glass) (5-1) Supporting lanthanum on foam glass and firing Lanthanum chloride heptahydrate was weighed out to a theoretical loading rate of 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 primarily made from colored glass (particle diameter: approximately 2-10 mm), specific gravity: 0.35-0.5) was weighed into a 50 mL centrifuge tube, and the lanthanum solution was added. Pure water was then added until the entire foam glass 3 particles were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25°C, and the lanthanum was allowed to load for one 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 in a gas-substituted electric furnace (HPM-0G, manufactured by AS ONE Corporation) at 250°C, 350°C, 450°C, 550°C, 650°C, or 750°C for 2 hours, 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 tube was then shaken in an incubator at 100 rpm and 25°C for 3 hours. The phosphate-phosphorus solution was then filtered through a syringe filter (Milipore, SLHN033NB) with a pore size of 0.45 μm. The same procedure as above was also carried out on uncalcined lanthanum-supported foam glass 3. The phosphate concentration of 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 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 concentration of phosphate phosphorus of 10 mg-P / L.

[0065] [Table 5]

[0066] <Result> As can be seen from Table 5 and FIG. 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) Supporting iron and lanthanum on foam glass and firing Iron(II) chloride tetrahydrate was weighed out to theoretical loading rates of 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.05%, 0.075%, 0.1%, 0.25%, or 0.5% by mass and dissolved in pure water to prepare iron solutions. Next, 8 g of foam glass 3 (trade 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 foam glass 3 particles were immersed. The centrifuge tube was then shaken at 100 rpm and 25°C in an incubator to allow iron to be loaded for one day. The glass 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 foamed glass 3 and iron-free foamed glass 3 by the following procedure. Lanthanum chloride heptahydrate was weighed out to a theoretical loading rate of 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 foam glass 3 without iron loading was weighed into a 50 mL centrifuge tube, and the lanthanum solution was added. Pure water was then added until the entire foam glass 3 particles were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25°C to load lanthanum for one 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). Next, the iron-lanthanum loaded foam glass 3 was fired at 350°C for 2 hours using a gas-exchange electric furnace (HPM-0G, manufactured by AS ONE Corporation).

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

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

[0070] (6-4) BET specific surface area measurement Furthermore, to confirm how the specific surface area of ​​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 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. to allow iron to be loaded for one day. The sample 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) to produce iron-loaded foam glass 3. The sample was then crushed in an agate mortar and subjected to BET specific surface area measurement by nitrogen gas adsorption using a specific surface area measurement device (FlowSorb III, manufactured by Micromeritics). Similarly, BET specific surface area measurement was performed on foam glass 3 without iron loading. The results are shown in Table 8 and FIG. 6.

[0071] [Table 6]

[0072] [Table 7]

[0073] [Table 8]

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

[0075] Experimental Example 7 (Study of lanthanum loading rate on iron-loaded foam glass) (7-1) Supporting iron and lanthanum on foam glass and firing Iron(II) chloride tetrahydrate was weighed out to a theoretical loading rate of 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 primarily made from colored glass (particle diameter: approximately 2-10 mm), specific gravity: 0.35-0.5) was weighed into a 50 mL centrifuge tube, and the iron solution was added. Pure water was then added until the entire foam glass 3 particles were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25°C to allow iron to be loaded for one 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 this iron-loaded foam glass 3 using the following procedure. Lanthanum chloride heptahydrate was weighed out to a theoretical loading rate of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 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 the entire foam glass 3 particles were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25°C to load lanthanum for one 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). The iron-lanthanum loaded foam glass 3 was then fired at 350°C for 2 hours using a gas-exchange 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 solution was added. The tube was then shaken at 100 rpm and 25°C for 3 hours using a shaker (Tokyo Rikakikai Co., Ltd., MMS-1020) in an incubator. The phosphate solution was then filtered through a 0.45 μm syringe filter (Milipore, SLHN033NB). The phosphate concentration of the filtrate was measured by molybdenum blue absorptiometry using a UV-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. Furthermore, a graph showing the relationship between the lanthanum support rate and the adsorption rate of phosphorus in the form of phosphate is shown in FIG.

[0077] [Table 9]

[0078] <Result> The graph shows the results of the adsorption rate of phosphate-phosphorus when the iron loading rate was 0.1% by mass and the lanthanum loading rate was changed. Table 9 and Figure 7 show that the adsorption rate of phosphate-phosphorus reached 94.6% when the lanthanum loading rate was 2% by mass. Therefore, the following experiment was conducted with the iron loading rate set to 0.1% by mass and the lanthanum loading rate set to 2% by mass.

[0079] Experimental Example 8 (Adsorption Rate and Adsorption Isotherm) (8-1) Supporting iron and lanthanum on foam glass and firing Iron(II) chloride tetrahydrate was weighed out to a theoretical loading rate of 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 primarily made from colored glass (particle diameter: approximately 2-10 mm), specific gravity: 0.35-0.5) was weighed into a 50 mL centrifuge tube, and the iron solution was added. Pure water was then added until the entire foam glass 3 particles were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25°C to allow iron to be loaded for one 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 this iron-loaded 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-loaded foam glass 3 was weighed into a 50 mL centrifuge tube, and the lanthanum solution was added. Pure water was then added until all of the foam glass 3 particles were immersed. The centrifuge tube was then shaken in an incubator at 100 rpm and 25°C to load lanthanum for one 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). Next, the iron-lanthanum-loaded foam glass 3 was fired at 350°C for 2 hours using a gas-purged electric furnace (HPM-0G, manufactured by AS ONE Corporation).

[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 the mixture was shaken in an incubator at 100 rpm and 25°C. Five mL of the solution was sampled at predetermined intervals and filtered through a 0.45 μm pore size syringe filter (Milipore, SLHN033NB). The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using a UV-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 capacity> q = S rem (C con -C sam ) / (1000 a) q: Phosphate adsorption amount (mg-P / g) S rem : Remaining solution volume (mL) C con : Control concentration (mg-P / L) C sam : Sample concentration (mg-P / L) a: Adsorbent dosage (g) The unit of the adsorption amount (mg-P / g) is the amount of phosphorus in the phosphate form, 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 FIG. 8, and the results when the initial phosphate phosphorus concentration was 10 mg-P / g are shown in Table 11 and FIG.

[0082] [Table 10]

[0083] [Table 11]

[0084] <Result> 8 and 9 are graphs showing the change over time in the amount of adsorbed phosphorus phosphate of foam glass 3 that supports 0.1 mass % of iron and 2 mass % of lanthanum and is fired at 350° C. for 2 hours. From Table 10 and FIG. 8, it can be seen that when the initial concentration of phosphate phosphorus 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. From Table 11 and FIG. 9, when the initial concentration of phosphate phosphorus 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 One gram of iron-lanthanum-supported foam glass 3 was placed in a 500 mL Erlenmeyer flask. Next, 500 mL of phosphate-phosphorus solution (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 the mixture was shaken in an incubator at 100 rpm and 25°C. After 48 hours, 5 mL of the solution was sampled and filtered through a 0.45 μm syringe filter (Milipore, SLHN033NB). The phosphate-phosphorus concentration of the filtrate was measured by molybdenum blue absorptiometry using a UV-visible spectrophotometer (Shimadzu Corporation, UV-2600) to measure the absorbance at 880 nm. The equilibrium adsorption amount was calculated as described above. The results are shown in Table 12 and Figure 10.

[0086] [Table 12]

[0087] <Result> Figure 10 shows the adsorption isotherm for the iron-lanthanum-loaded foam glass composite. 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 iron and lanthanum on foam glass and firing The foam glass used was foam glass 5 (trade name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass made mainly of colored glass (particle diameter: approximately 10 to 20 mm), specific gravity: 0.35 to 0.5). This foam glass 5 was obtained by using a sieve to select foam glass 3 (trade name Supersol (registered trademark) L2, manufactured by Kokko Co., Ltd., foam glass made mainly 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 loading 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 out and placed in a 2 L polypropylene (PP) bottle (Azwan Corporation, Eyeboy wide-mouth bottle), and the iron solution was added. Pure water was then added until the entire foam glass 5 particles were immersed. The container containing the foam glass 5 and the iron solution was then reciprocally shaken horizontally in a shaker (Yamato Scientific Co., Ltd., Shaker (SA300)) at 25°C for 18 hours or more to load the iron. The container was then dried at 100°C for 18 hours or more in a dryer (Yamato Scientific Co., Ltd., Constant Temperature Dryer DX41). Lanthanum was loaded onto the iron-loaded foam glass 5 using the following procedure. Lanthanum chloride heptahydrate was weighed out to a theoretical loading rate of 3.5% by mass and dissolved in pure water to prepare a lanthanum solution. Next, 2 L of iron-loaded foam glass 5 was weighed out and placed in a 2 L polypropylene (PP) bottle (Azwan Corporation, Eyeboy wide-mouth bottle), and the lanthanum solution was added. Pure water was then added until the entire foam glass 5 particles were immersed. The container containing the iron-loaded foam glass 5 and the lanthanum solution was then reciprocally shaken horizontally in a shaker (Yamato Scientific Co., Ltd., Shaker (SA300)) at 25°C for 18 hours or more to load the lanthanum. The mixture was then dried in a dryer (Yamato Scientific Co., Ltd., Constant Temperature Dryer DX41) at 100°C for 18 hours or more. 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 The produced iron-lanthanum-supported foam glass 5 was used to measure the phosphorus adsorption rate using a phosphorus removal device shown in Figure 11. The phosphorus removal device is a device with a scale of 1 / 1000 of that of an actual septic tank. The operating conditions are shown in Table 13 below. The composition of the raw water, the wastewater from the septic tank, 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, wastewater 3: wastewater with an initial phosphate-phosphorus concentration of 50 mg-P / L).

[0090] [Table 13]

[0091] [Table 14]

[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. NH4-N stands for ammonia nitrogen. PO4-P stands for phosphate phosphorus. TP stands for 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 for 24 hours at 20°C. The iron-lanthanum-supported foam glass 5 or foam glass 5 was filled into the phosphorus removal device, and sampling was carried out before operating the pump (0 hour), 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] [Table 15]

[0095] [Table 16]

[0096] [Table 17]

[0097] <Result> Tables 15 to 17 and FIGS. 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. [Industrial Applicability]

[0098] The foam glass composite material of the present invention 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 a compound thereof, and lanthanum or a compound thereof, The foam glass composite material is an iron-lanthanum-loaded foam glass composite material in which iron or a compound thereof and lanthanum or a compound thereof are loaded on foam glass, The loading rate of the iron or the compound thereof is 0.005 to 0.5 mass% relative to the mass of the foam glass, The loading rate of the lanthanum or a compound thereof is 0.5 to 3.5 mass% relative to the mass of the foam glass, and Foam glass composite material for adsorption removal of phosphorus from wastewater.

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

3. 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.

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

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

6. The step of mixing the foam glass with iron or a compound thereof and lanthanum or a compound thereof, A step of supporting iron or a compound thereof on the foam glass to obtain an iron-supported foam glass composite material; and The method for producing a foam glass composite material according to claim 5, comprising 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.

7. The method for producing a foam glass composite material according to claim 6, further comprising a step of firing the iron-lanthanum-supported foam glass composite material at 700°C or less.

8. A phosphorus adsorbent comprising the foam glass composite material according to any one of claims 1 to 4.

9. A wastewater treatment device comprising the phosphorus adsorbent according to claim 8.

10. A method for adsorbing phosphorus, comprising contacting the phosphorus adsorbent according to claim 8 with a liquid containing phosphorus.

11. A method for removing phosphorus, comprising adsorbing and removing phosphorus from wastewater using the phosphorus adsorbent according to claim 8.

12. 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, comprising: The foam glass composite material is an iron-lanthanum-loaded foam glass composite material in which iron or a compound thereof and lanthanum or a compound thereof are loaded on foam glass, The loading rate of the iron or its compound is 0.005 to 0.5 mass% with respect to the mass of the foam glass, and The method for use, wherein the loading rate of the lanthanum or a compound thereof is 0.5 to 3.5 mass% relative to the mass of the foam glass.

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