KR102323503B1 - eco-friendly Foam and method for producing the same - Google Patents

Abstract

The foam for supporting microorganisms according to the present invention has excellent adhesion and affinity for microorganisms to the pore area in the foam, greatly improves the environment for supporting microorganisms, and has a large surface area, so that sufficient water treatment efficiency can be secured after supporting microorganisms.

Description

Eco-friendly foam and method for producing the same

The present invention relates to an eco-friendly foam and a method for manufacturing the same.

Household water used and thrown away or industrial wastewater generated at industrial sites goes through various treatment processes. Specifically, physical treatment through filtration, chemical treatment using chemicals, and biological degradation using microorganisms may be performed, and wastewater is generally treated using all of these chemical treatment, physical treatment, and biological treatment. Specifically, biological decomposition using microorganisms mainly refers to a step of decomposing organic matter, etc. contained in domestic wastewater, etc. through catabolism.

Various methods may be used for this biological treatment, but in order to continuously treat wastewater while treating a large amount of wastewater, microorganisms may be supported on a carrier so that the fluidized-bed wastewater may come into contact with microorganisms as it flows. There are various types of such carriers for supporting microorganisms, but specifically, ceramics, soil, or polymer resins may be used. In the case of using a polymer resin, a method of foaming the polymer to increase the contact area with microorganisms is also used.

On the other hand, in the case of a carrier in which microorganisms are filtered, when applied to an actual water treatment facility, it should be designed to maximize the area in contact with wastewater and secure a sufficient flow rate to secure the treatment flow per unit time, and a lot of research has been done on this. . For example, JP3436947B2 discloses a filtering device including a filter medium having a particle diameter of 0.5 to 1 mm by pulverizing a porous plastic.

However, as a method of changing the structure, shape, etc. of the foam has reached its limit due to many advances in the effect of supporting microorganisms, it is necessary to seek technical improvement of other methods.

JP3436947B2 (1994.10.04)

It is an object of the present invention to provide a foam and a method for manufacturing the same, which are environmentally friendly and have excellent mechanical properties such as pore properties and structural stability compared to conventional foamed plastics.

Another object of the present invention is to provide a foam having excellent adhesion and affinity for microorganisms to the pore area in the foam and greatly improved environment for supporting microorganisms and a method for manufacturing the same.

Another object of the present invention is to provide a foam capable of securing sufficient water treatment efficiency after supporting microorganisms due to a large surface area and a method for manufacturing the same.

The method for producing an eco-friendly foam according to the present invention includes the steps of: s1) kneading and extruding a resin composition comprising a base resin and a natural material to prepare an extrudate, and s2) manufacturing a foam by pressurizing the extrudate include

In the manufacturing method according to an embodiment of the present invention, in step s1), the natural material may be a plant stem, root, leaf, fruit, peel, or a mixture thereof.

In the manufacturing method according to an embodiment of the present invention, the natural material in step s1) may be wheat flour, corn starch, or a mixture thereof.

In the manufacturing method according to an embodiment of the present invention, in step s1), the natural material may have a moisture content of 10% by weight or less.

In the manufacturing method according to an embodiment of the present invention, before step s1), drying the natural material may be further included.

In the manufacturing method according to an embodiment of the present invention, in step s1), the resin composition may contain 0.1 to 10 parts by weight of a natural material based on 100 parts by weight of the base resin.

In the manufacturing method according to an embodiment of the present invention, in step s1), the base resin is selected from the group consisting of polyolefin-based resins, polyvinyl chloride-based resins, polystyrene-based resins, polyester resins, and copolymers thereof. It may include one or two or more.

In the manufacturing method according to an embodiment of the present invention, before the step s1), it may further include a fiber surface treatment step of a natural material.

In the manufacturing method according to an embodiment of the present invention, in step s2), the pressurized foaming may be performed by introducing the extrudate, the blowing agent and the dispersion medium into the reactor, and controlling the pressure in the reactor.

In the manufacturing method according to an embodiment of the present invention, in step s2), the foaming temperature may be 100 to 250° C. during pressurized foaming, and the foaming pressure may be 0.5 to 10 Mpa.

In the manufacturing method according to an embodiment of the present invention, in step s2), the blowing agent may be any one or two or more selected from the group consisting of carbon dioxide, carbon monoxide, nitrogen, argon, helium, butane and pentane.

In the manufacturing method according to an embodiment of the present invention, the foam may be for supporting microorganisms.

The present invention includes a foam produced by the above-described manufacturing method.

The foam according to an embodiment of the present invention may be a foam for biological water treatment, including pores, in which microorganisms are supported.

The present invention includes a foam produced by the above-described manufacturing method, or a method for purifying wastewater using the above-mentioned foam.

A method for purifying wastewater according to the present invention comprises the step of purifying by contacting the wastewater with a foam.

In the wastewater treatment method using a foam according to an embodiment of the present invention, a pretreatment step of precipitating and removing contaminants contained in wastewater using natural precipitation, and a filling pipe filled with the foam loaded with microorganisms in the treated water that has undergone the pretreatment step It may include a purification step passing through.

The wastewater treatment method using a foam according to an embodiment of the present invention may include a purification step in which wastewater containing microorganisms passes through a filling tube filled with the foam.

The foam according to the present invention is environmentally friendly and has excellent mechanical properties such as pore properties and structural stability compared to conventional foamed plastics.

In addition, the foam according to the present invention has excellent adhesion and affinity for microorganisms to the pore area in the foam, and has the effect of greatly improving the environment for supporting microorganisms.

In addition, since the foam according to the present invention has a large surface area, it is possible to secure sufficient water treatment efficiency after supporting microorganisms.

Even if the effects are not explicitly mentioned in the present invention, the effects described in the specification expected by the technical features of the present invention and the inherent effects thereof are treated as described in the specification of the present invention.

1 is a scanning electron microscope photograph of the foam prepared in Example 1.
2 is an optical photograph of the foam prepared in Example 1.
3 is a scanning electron microscope photograph of the foam prepared in Example 6.

Hereinafter, an eco-friendly foam and a manufacturing method thereof according to the present invention will be described in detail.

Unless otherwise defined in technical terms and scientific terms used in this specification, those of ordinary skill in the art to which this invention belongs have the meanings commonly understood, and the subject matter of the present invention is unnecessary in the following description. Descriptions of known functions and configurations that may be blurred will be omitted.

A singular form of a term used herein may be construed to include a plural form unless otherwise indicated.

s1, s2, s3, ... as referred to herein; a1, a2, a3, ...; b1, b2, b3, ...; a, b, c, ...; The term itself referring to each step, such as etc., is only used to refer to a certain step, means, etc., and should not be construed as meaning an order relationship of the respective objects referred to by the terms.

In the present specification, the unit of % used without special mention means % by weight unless otherwise specified.

Conventional foams have a problem in that, as a hydrophobic polymer is usually used as a base resin, the adhesion of microorganisms is remarkably reduced, and it is not suitable for the culture environment of microorganisms. Accordingly, the present inventors intend to provide a foam with greatly improved adhesion of microorganisms to the pore area in the foam and a support environment, and a method for manufacturing the same.

The manufacturing method of the foam according to the present invention includes the steps of s1) kneading and extruding a resin composition comprising a base resin and a natural material to prepare an extrudate, and s2) preparing a foam by pressurizing the extrudate. do. As the foam according to the present invention is manufactured including a natural material, it has excellent adhesion and affinity for microorganisms to the pore area in the foam, and the effect of greatly improving the environment for supporting microorganisms is realized. In particular, in the present invention, pressure foaming (physical foaming) proceeds after the resin composition including the base resin and natural material is extruded, thereby achieving the above effect. Specifically, when extrusion and foaming proceed simultaneously, or when pressurized foaming does not proceed after extrusion, a pore area of sufficient size by natural materials cannot be expected, and microbial adhesion and affinity of the foam cannot be expected. Structural stability obtained in step s1) when a process separated from extrusion and foaming including step s2) in which pressurized foaming is secondarily performed after step s1) in which a resin containing a natural material is primarily extruded And as a high-density extrudate is obtained, the extrudate is effectively physically foamed in step s2) afterward, so that the internal pore activation and hydrophilization modification effect by a natural material is improved.

The natural material may be a compound, substance, or mixture thereof produced by an organism existing in nature. Specifically, the natural material may be a vegetable natural material, and more specifically, the natural material may be a cellulose-based natural material derived from a plant. Examples of cellulose-based natural materials include, but are not limited to, plant stems, roots, leaves, fruits, skins, or mixtures thereof.

In an advantageous embodiment, the vegetable natural material may be wheat flour, corn starch, or a mixture thereof. Wheat bran means wheat bran. Specifically, wheat flour is the remainder of separating wheat flour and germ from wheat flour and forms a powder form. Wheat hull is mostly composed of the outer skin of the seed and has a small amount of endosperm and germ part. More specifically, the wheat skin consists of the seed coat of wheat, the core layer, the aloe layer, and the like, and consists of water, fat, protein, ash, and carbohydrates. Corn starch is the starch extracted from the endosperm of corn, and is the whitest and finest of all starches. Corn starch is a polymeric carbohydrate in which a large number of glucose units are linked by glycosidic bonds. The grains of corn starch are very hard crystalline, but when mixed with water and heated, they become loose while absorbing moisture. Corn, which is a raw material for corn starch, is not particularly limited. For example, corn, which is a raw material for corn starch, may be varieties such as dent, hard (flint), sweet corn, popcorn, soft (soft), etc., and in the case of amylose content, general corn (amylose content of about 27%), waxy corn, high amylose corn (amylose content of 60% or more), etc., but is not limited thereto.

Wheat hull, corn starch, or a mixture thereof is mixed into a hydrophobic base resin and pressurized after extrusion, whereby the surface of the foam to which microorganisms can be attached is hydrophilically modified, thereby significantly improving the adhesion and affinity of microorganisms. can be obtained Specifically, through a two-step process of mixing a natural material and a base resin, extruding the mixture, and then foaming, the hydrophilicity of the foam can be significantly improved than that of the extruded body. More specifically, when wheat bran, corn starch, or a mixture thereof is used as a natural material, a water droplet (deionized water, 2 ml) is dropped from a height of 1 cm on the macroscopically flat side of the foam to determine the water contact angle in the equilibrium state. When measured, when the water contact angle is 10° or less, specifically 5° or less, more specifically 1° or less, and substantially 0°, the foam can exhibit excellent hydrophilicity. Furthermore, when the natural material is wheat bran or corn starch, it has a substantially 0° water contact angle, and the time it takes for the water droplets to reach the equilibrium state is extremely short, less than 3 seconds, which has higher hydrophilic surface properties than any other natural material. can represent In addition, when wheat flour, corn starch, or a mixture thereof is used as a natural material, it acts as an essential nutrient required for assimilation of microorganisms attached to the foam, thereby increasing the concentration of microorganisms attached to the pores.

In step s1), it may be preferable that the natural material has a moisture content of 10% by weight or less, specifically 0.1 to 10% by weight, more specifically 0.1 to 5% by weight, even more specifically, 0.1 to 3% by weight . When the moisture content of the natural material is higher than the upper limit, extrusion and foaming may occur at the same time as moisture is vaporized by a high temperature in the extrusion process of step s1). Accordingly, the probability of producing an unspecified, random-shaped foam increases, reproducibility is low, and the internal pore formation rate by physical pressure is also significantly reduced, and durability may also be relatively reduced. That is, in general, since natural materials have a moisture content of about 12% by weight or more, which exceeds 10% by weight, when a normal natural material is used as it is without controlling the moisture content, the above-described problems may occur. Specifically, when the moisture content of the natural material exceeds 10% by weight, undesired foaming may occur in the extrusion step, and if foaming has already occurred even partially in the extrusion step, the foaming rate during physical foaming in step s2) Not only this falls, but also durability may be reduced due to non-uniform foaming.

As for natural materials, the means for controlling the moisture content is not particularly limited, and a drying means may be cited as an example. That is, the manufacturing method of the foam according to the present invention may further include the step of drying the natural material before step s1) in order to control the moisture content of the natural material. The drying temperature and drying time may be sufficient as long as the natural material can satisfy the required moisture content.

The manufacturing method of the foam according to an embodiment of the present invention, before the step s1), more preferably, before the drying step, may further include a fiber surface treatment step of a natural material. The fiber surface treatment may be a hydrophilic surface treatment of the fiber. Since the hydrophilic surface-treated natural material is used, not only is it better dispersed in a dispersion medium such as water in step s2), but also the outer surface of the foam and the surface of the internal pores of the foam are hydrophilized, so that the attachment of microorganisms is more effective can be In detail, when the hydrophilization surface treatment is carried out in advance, the surface of the natural material is roughened and the specific surface area is increased, which is accompanied by physical modification, and at the same time, chemical modification according to the introduction of acid groups on the surface may be accompanied. According to the physical and chemical modification, the melt-kneading process and the pressurized foaming process may be affected, thereby implementing the effect of improving the adhesion of microorganisms to the pore area in the foam and the supporting environment.

An example of the hydrophilization surface treatment means is acid treatment, and specifically, means for drying the natural material after immersing the natural material in an aqueous solution containing an inorganic acid such as sulfuric acid, hydrochloric acid, nitric acid, or a mixed acid thereof for a predetermined time. have. The immersion temperature and immersion time are not particularly limited, but may be preferably in the low temperature range of 2 to 14° C. and in the range of 6 to 18 hours. The acid concentration of the aqueous solution is not particularly limited, and may be, for example, 20 to 95% by weight. In addition, ethanol may be additionally included in the aqueous solution, and in this case, it is possible to induce more effective hydrophilization of natural materials.

In step s1), the weight ratio of the base resin and the natural material is not particularly limited. For example, the resin composition preferably contains 0.1 to 10 parts by weight of the natural material, specifically 0.5 to 7 parts by weight, based on 100 parts by weight of the base resin. can do. A foam manufactured by satisfying this may have a high specific surface area and sufficient structural stability may be secured.

In step s1), the base resin is not limited as long as it is a polymer capable of forming a foam, for example, any one selected from polyolefin-based resins, polyvinyl chloride resins, polystyrene resins, ester resins, and copolymers of the resins. It may include two or more. As a specific example, the polyolefin-based resin may include polyethylene and polypropylene, and the copolymer may have a random form, an alternating form, and a block form. Although the base resin as described above is chemically hydrophobic, the foam finally prepared by the above-described means has high hydrophilicity. As a preferred example, a poly(propylene-ethylene) random copolymer may be selected as the base resin.

As a more preferred example, when a poly(propylene-ethylene) random copolymer is selected as the base resin and wheat flour, corn starch, or a mixture thereof is selected as a natural material, wheat flour and poly(propylene-ethylene) random copolymer While the viscoelastic properties of the coal are very high compared to wheat bran or corn starch, the poly(propylene-ethylene) random copolymer and wheat bran or corn starch, especially wheat bran, have excellent adhesion properties to each other. Due to the above properties, when foaming under pressure after extrusion of the resin composition, the high viscoelasticity of the poly(propylene-ethylene) random copolymer can generate pores at a very high ratio, and wheat flour or corn starch, which has low viscoelastic properties, has high viscoelasticity in the foaming process. It is mainly located on the inner wall of the pores due to its adhesive force, so it is effective for the attachment and culture of microorganisms. Among the total weight of the wheat hide, corn starch, or a mixture thereof contained in the foam, the weight ratio of the wheat hide located on the outer surface of the foam and the inner pore surface of the foam may be 60% by weight or more, preferably 70% by weight, but is not limited thereto. 95% by weight or less.

Melt flow rate (MFR) of the base resin is not particularly limited, and may be, for example, 2 to 20 g/10 min at 230°C, and a melting point (MP) of 120 to 180°C. In addition, the weight average molecular weight of the base resin is not particularly limited, and may be, for example, 5,000 to 1,000,000 g/mol. However, this is only described as a specific example, and the present invention is not necessarily limited thereto.

In step s1), the extrusion temperature may be higher than the temperature at which the resin composition can be melted, and for example, a melting range of the thermoplastic resin such as 130 to 250° C. may be mentioned.

In step s1), the shape and size of the obtained extrudate may be appropriately adjusted to suit the required shape and size of the final manufactured foam. As a specific example, the shape may include various types such as a spherical shape, a rod shape, a cylindrical shape, a cylindrical shape, a cross shape, and an n-hedron (n is 4 or more). Examples of the size may be 0.1 to 5 cm, but it is not limited because it may be appropriately adjusted according to the scale of use.

In step s2), the pressurized foaming may be performed by introducing the extrudate, the blowing agent and the dispersion medium into the reactor, and controlling the pressure in the reactor. As described above, in the present invention, since the above-described effect is realized as the process of pressurized foaming is performed after extrusion, pressurized foaming is one of the important components for implementing the effect. This physical foaming is made by pressurization, and the extrudate containing the natural material is converted into a very low-density foam having internal pores (including open pores) due to the instantaneous pressure change. At this time, the content of the extrudate, the foaming agent and the dispersion medium may be appropriately adjusted, for example, 0.5 to 30 parts by weight of the foaming agent and 50 to 500 parts by weight of the dispersion medium based on 100 parts by weight of the extrudate, but the present invention is not limited thereto is of course

In step s2), the foaming temperature and foaming pressure during pressurized foaming may be sufficient as long as the extrudate can be expanded and foamed, for example, may be 100 to 250° C. and 0.5 to 10 MPa, respectively. However, this is only described as a preferred example, and the present invention is not necessarily limited thereto.

In step s2), when the required foaming temperature and/or the required foaming pressure is reached after the reactor is sealed inside, the foaming temperature and foaming pressure may be maintained for a predetermined time to maintain a high-temperature peak calorific value. In this case, the holding time is not particularly limited, but may be, for example, 3 to 30 minutes. However, this is only described as a preferred example, and the present invention is not necessarily limited thereto.

In step s2), the foaming agent may be any physical foaming agent that allows the extrudate to expand and foam due to a change in pressure. As a specific example, any one or a mixture of two or more selected from an organic physical foaming agent such as an aliphatic hydrocarbon or a halogenated hydrocarbon, and an inorganic physical foaming agent may be used. In this case, the aliphatic hydrocarbons may mean C3 to C6 aliphatic hydrocarbons such as n-butane, i-butane or n-pentane, and the halogenated hydrocarbons include ethyl chloride, 2,3,3,3-tetrafluoro-1- halogen substituted aliphatic hydrocarbons such as propene or trans-1,3,3,3-tetrafluoro-1-propene and the like. The inorganic physical foaming agent may include, for example, any one or two or more selected from carbon dioxide, carbon monoxide, nitrogen, argon, helium, air, and the like. However, this is only described as a preferred example, and the present invention is not necessarily limited thereto.

In one embodiment of the present invention, in step s2), any one or two or more additives selected from a dispersing agent, a hydrophilic powder, and a foaming activator may be added together in the reactor together with the foaming agent and the dispersion medium. As a specific example, the dispersion medium may be any medium capable of dispersing the extrudate, for example, water or an organic solvent. and waxes and metal stearate. A variety of known surfactants may be used, and examples thereof include anionic surfactants such as sodium alkylbenzenesulfonate. In addition, the hydrophilic powder includes calcium carbonate, activated clay, aluminum hydroxide, slaked lime, zeolite, bentonite, diatomaceous earth, montmorillonite, illite, stilbite, kaolinite, pyrophyllite, andalusite, kyanite, miranite, grovenite, Amesite, cordierite, feldspar, elephant metakaolin, hectorite, saponite, hectorite fluoride, beidellite, nontronite, stevensite, vermiculite, volconite, soconite, magadite, kenyarite It may include any one or two or more selected from smectite, attapulgite, sepiolite, halloysite, permutite, and the like. In addition, the foaming activator may include any one or two or more selected from aluminum sulfate, potassium aluminum sulfate, aluminum ammonium sulfate, ferric sulfate, ferric polysulfate, sulfuric acid, sulfamic acid, sodium hydroxide and potassium hydroxide. The amount of the additive used is not particularly limited, and for example, may be used in an amount of 0.001 to 5 parts by weight or 0.1 to 10 parts by weight, depending on the type of additive, based on 100 parts by weight of the extrudate.

The foam according to the invention may have an apparent density of from 10 to 180 g/l, in particular from 10 to 100 g/l.

The foam according to the present invention may include pores, and the volume ratio of pores in the total volume of the foam may be 60% or more, specifically 70% or more, 80% or more, or 90% or more, and may be 99% or less.

In this case, the average diameter of the pores may be 20 to 300 μm, specifically 50 to 250 μm, and more specifically 80 to 250 μm.

As described above, the foam according to the present invention can be used for supporting microorganisms, and more specifically, it can be used for biochemical water treatment. Specifically, as the foam can be used for biochemical water treatment purposes, the treatment efficiency of the fluidized bed wastewater treatment device is high, the treatment tank volume is reduced, and the effect of preventing the outflow of sludge due to fluctuations in the flow rate of the inlet wastewater is obtained. have. In addition, it can be used for biochemical water treatment as a practically excellent carrier because of its high stability against fluctuations in wastewater quality and quantity.

In addition to supporting microorganisms, the foam according to the present invention can be applied without limitation if it is a field that can be used as a material in which pores are formed, that is, if it is a foamed plastic field, for example, it can be used for various purposes such as insulation, filler, buoyancy material, interior / exterior material, etc. of course there is

The wastewater treatment method using the foam according to the present invention includes the step of being purified by contacting the foam.

Specifically, the wastewater treatment method using the foam according to an embodiment of the present invention includes a pretreatment step of precipitating and removing contaminants contained in wastewater using natural sedimentation, and the treated water subjected to the pretreatment step, wherein the foam is loaded with microorganisms. It may include a purification step passing through.

When wastewater is treated through this wastewater treatment method, the amount of permeation per unit time can be increased while sufficiently securing a contact area between microorganisms and wastewater in the purification step, so that a large amount of wastewater can be treated in a short period of time. have.

The pretreatment step may refer to a step of primarily removing solid contaminants contained in wastewater by using a method such as filtration. By going through this pre-treatment step, it is possible to prevent the problem that the purification efficiency is rapidly reduced as solid contaminants are filtered through the foam during purification using microorganisms later.

The means for supporting the microorganisms on the foam is generally any method of supporting the microorganisms on the carrier, and specifically, Korean Patent No. 10-0945309, Korean Patent No. 10-1002696, or Korean Patent Application Laid-Open Publication No. 10-2008-0092091. A method may be used, and more specifically, a method of immersing the foam in a solution containing a microbial culture solution may be used.

In addition, the wastewater treatment method using the foam according to another aspect of the present invention may include a purification step in which the wastewater containing microorganisms passes through the foam filling tube. As described above, the foam can be used in a state in which the microorganism is supported on the foam, but it can also be used in a state in which the initial microorganism is not supported. Specifically, the biochemical reaction of microorganisms by the foam, for example, BOD reduction rate, can be significantly increased even when the wastewater containing the microorganisms subjected to biochemical treatment in the aerobic reactor passes the foam through the filling tube. That is, the wastewater treatment method using a foam according to an aspect of the present invention comprises the steps of performing biochemical treatment by introducing microorganisms and wastewater into an aerobic reactor, and wastewater containing the microorganisms subjected to the biochemical treatment, wherein the foam is It may include a purification step through the filling tube.

Furthermore, the wastewater treatment method according to an embodiment of the present invention may further include a washing step of washing the foam after the purification step. Through such washing, it is possible to remove substances such as suspended matter existing in the foam, and to secure high wastewater treatment efficiency in the long term. Furthermore, the foam that has undergone the washing step may be subjected to a purification step again, and of course, the washing step and the purification step may be alternately performed.

When the foam according to the present invention is filled in the filling tube, the porosity, which is the ratio of the empty space to the total volume of the filling tube in which the foam is filled, may be 30 to 60%.

The microorganism may be any biochemical treatment possible in the field of wastewater treatment, for example, the microorganism is Bacillus sp. , Leuconostoc sp. , Lactobacillus sp. , Lactococcus genus ( Lactococcus sp. ), Streptococcus sp. , Aspergillus sp. , Saccharomyces sp. , Pseudomonas sp. , and Candida sp. It may include any one or two or more selected from the like. However, this is only described as a specific example, and the present invention is not necessarily limited thereto.

Hereinafter, the present invention will be described in detail by way of Examples, but these are for describing the present invention in more detail, and the scope of the present invention is not limited by the Examples below.

<Kneading and extrusion process of wheat flour, a natural material>

First, the wheat blood was dried at 50° C. to prepare a wheat blood having a moisture content of 3% by weight or less.

990 g of a propylene-ethylene random copolymer having a melt flow rate (MFR, at 230°C) of 7 g/10 min and a melting point (MP) of 140°C and a moisture content of 3 wt% or less and an average particle size 10 g of this 20 ㎛ wheat bran (bran) was blended and melt-kneaded at 170°C. This molten composition was fed to a twin-screw extruder having an inner diameter of 20 mm, and poured into a water bath while extruding in a strand shape, and cooled. The cooled extrudate was cut to about 2 mg and dried to obtain resin particles. At this time, under the extrusion conditions, the raw material supply part of the extruder is filled with the molten composition, and with respect to the discharge amount of the raw material resin of the extruder under the normal filling operation condition, the discharge amount of the raw material resin by the same screw rotation speed during the filling operation condition, the resin It was extruded by supplying while adjusting the supply with a capacitive feeder. Here, the discharge amount during the gear operation with respect to the full operation was adjusted to 70%. The discharged resin particles are manufactured in the form of mini-pellets in a cross shape through the shape of the discharge part.

<Pressure foaming process>

3 kg of the resin particles were dispersed in 3 kg of water in a sealed container equipped with a stirrer, and 10 g of kaolin, 2 g of sodium alkylbenzenesulfonate, and 1 g of aluminum sulfate were additionally supplied during dispersion. In addition, 80 g of carbon dioxide was supplied in the sealed container and the temperature was raised to 130° C. to adjust the pressure in the sealed container to 6.0 Mpa and then maintained for 15 minutes. The airtight container was then opened and released under atmospheric pressure to produce a foam with an apparent density of 45 g/L. 1 is a scanning electron microscope photograph of the foam (cross-shaped mini pellets) prepared in Example 1. 2 is an optical photograph of the foam prepared in Example 1.

In Example 1, a foam was prepared in the same manner as in Example 1, except that 970 g of propylene-ethylene random copolymer and 30 g of wheat flour were used in the kneading and extrusion process.

In Example 1, a foam was prepared in the same manner as in Example 1, except that 950 g of propylene-ethylene random copolymer and 50 g of wheat flour were used in the kneading and extrusion process.

In Example 1, a foam was prepared in the same manner as in Example 1, except that in the kneading and extrusion process, an acid-treated wheat flour through the following acid treatment process was used.

<Acid treatment process>

The natural material was immersed in a mixture containing 20 ml of ethanol and 15 ml of 0.5 M aqueous sulfuric acid solution, irradiated with ultrasonic waves at 25° C. for 1 hour, and then dried at 50° C. to obtain an acid-treated natural material having a water content of 3% or less. .

In Example 1, a foam was prepared in the same manner as in Example 1, except that wheat skin having a water content of 12.15% was used instead of wheat skin having a water content of 3% or less in the kneading and extrusion process.

<Kneading and Extrusion Process of Corn Starch, a Natural Material>

First, corn starch having a moisture content of 3% or less was prepared by drying at 50°C.

The corn starch and a propylene-ethylene random copolymer having a melt flow rate, MFR, at 230° C.) of 7 g/10 min and a melting point (MP) of 140° C. were sufficiently kneaded to obtain 900 g of the copolymer. A masterbatch containing 100 g of corn starch was prepared.

Then, 50 g of the masterbatch was melt-kneaded at 170°C. This molten composition was fed to a twin-screw extruder having an inner diameter of 20 mm, and poured into a water bath while extruding in a strand shape, and cooled. The cooled extrudate was cut to about 2 mg and dried to obtain resin particles. At this time, under the extrusion conditions, the raw material supply part of the extruder is filled with the molten composition, and with respect to the discharge amount of the raw material resin of the extruder under the normal filling operation condition, the discharge amount of the raw material resin by the same screw rotation speed during the filling operation condition, the resin It was extruded by supplying while adjusting the supply with a capacitive feeder. Here, the discharge amount during the gear operation with respect to the full operation was adjusted to 70%. The discharged resin particles are manufactured in the form of mini-pellets in a cross shape through the shape of the discharge part.

<Pressure foaming process>

3 kg of the resin particles were dispersed in 3 kg of water in a sealed container equipped with a stirrer, and 10 g of kaolin, 2 g of sodium alkylbenzenesulfonate, and 1 g of aluminum sulfate were additionally supplied during dispersion. In addition, 80 g of carbon dioxide was supplied in the sealed container and the temperature was raised to 130° C. to adjust the pressure in the sealed container to 6.0 Mpa and then maintained for 15 minutes. The airtight container was then opened and released under atmospheric pressure to produce a foam with an apparent density of 45 g/L. 3 is a scanning electron microscope photograph of the foam (cross-shaped mini-pellets) prepared in Example 6. Comparing FIGS. 1 and 3 , it can be seen that in the case of corn starch, more uniform pores are formed throughout the pellet.

[Comparative Example 1]

In Example 1, in the kneading and extrusion process, the same as in Example 1, except that wheat skin having a water content of 12.15% was used instead of wheat skin having a water content of 3% or less, and the pressure foaming process was not performed. The foam was prepared by the method. At this time, as the moisture content of 10% by weight or more wheat blood is used, it is possible to foam the resin particles by the moisture of the wheat blood even by extrusion in the atmospheric atmosphere.

[Comparative Example 2]

In Example 1, a foam was prepared in the same manner as in Example 1, except that wheat blood was not used.

[Experimental Example 1]

<Evaluation of BOD reduction rate of foam>

The foams of Examples 1 to 5 and Comparative Example 1 were filled in an aerobic reactor with a capacity of 100 L so as to be 25% by volume, and sewage having a Biochemical oxygen demand (BOD) of 300 ppm was discharged at 20°C. The initial driving was started. The BOD reduction rate was measured when the hydraulic retention time (HRT) of the reactor was 3 hours by controlling the inflow and outflow flow rates, and the results are shown in Table 1 below. BOD measurement was measured based on what is stipulated in the Enforcement Regulations of the Environmental Conservation Act.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 BOD reduction rate (%) 91.3 92.9 94.1 98.2 84.1 60.8

In Table 1, it can be seen from Examples 1 to 3 that the BOD reduction rate increases as the content of wheat blood increases. With this, it can be seen from Example 4 that when acid-treated wheat blood is used instead of conventional wheat blood, the BOD reduction rate is significantly increased. This result is due to the incorporation of wheat blood into the hydrophobic base resin, and the surface of the foam to which microorganisms such as the outer surface of the foam and the inner surface of the pores of the foam can be attached is hydrophilicized by the wheat blood. . Furthermore, when sulfuric acid-treated wheat blood is used, it can be seen that better results are achieved, which is a physical modification in which the specific surface area is increased by roughening the surface of wheat blood by sulfuric acid treatment and chemical modification due to the introduction of sulfonic acid groups on the surface. , which affects the melt-kneading process and the pressurized foaming process, resulting in an increase in the effect of improving the adhesion of microorganisms to the pore area in the foam and the supporting environment.

In the case of Example 5, compared to the case of Examples 1 to 4, it showed a low BOD reduction rate. This is considered to be due to the fact that, as wheat flour with a high water content is mixed into the base resin in the kneading and extrusion process, foaming proceeds in the extrusion process, and the structural stability and durability of the resin particles are deteriorated. Specifically, in Examples 1 to 4, no foaming occurred during the extrusion process, but in the case of Example 5, it was confirmed that constant foaming already occurred during extrusion. In the extrusion process, the foaming caused by a high content of moisture in the wheat hides significantly lowers the effect of increasing internal pores and specific surface area compared to the case of pressurized foaming. In addition, the foamed resin particles are significantly inferior in structural stability and durability compared to non-foamed resin particles in which wheat blood having a low moisture content is used. Therefore, when the resin particles foamed by the high content of moisture in the wheat blood during the extrusion process are then pressurized and foamed, the probability of producing an unspecified random foam is increased, the reproducibility is low, and internal pores are formed by physical pressure. Not only the rate is significantly reduced, but also the durability is relatively reduced. From these results, it can be seen that the smaller the moisture content of the wheat blood, the more preferably 10% by weight or less, 5% by weight or less, preferably 3% by weight or less.

On the other hand, Comparative Example 1 showed a significantly lower BOD reduction rate compared to Examples. This is considered to be due to the fact that the microbial loading area of the foam itself was not significantly improved as the pressurized foaming was not performed. From these results, it can be seen that the physical foaming of wheat blood must be performed in the base resin to greatly affect the adhesion of microorganisms to the pore area in the foam and the improvement of the supporting environment. In the case of Example 6, it is a result of manufacturing an eco-friendly foam using corn starch, and a reduction rate similar to that of Examples 1 to 3 using wheat blood was confirmed as a result of measuring the BOD reduction rate.

[Experimental Example 2]

<Evaluation of mechanical properties of foam>

The pore size, porosity and structural stability of the foams of Examples 1 to 4 and Comparative Example 1 were evaluated. As a result, in the case of Examples 1 to 4 in which wheat blood was used, there was substantially no significant decrease in structural stability compared to Comparative Example 2 in which wheat blood was not used, and also in the pore size and porosity of the foam. It was confirmed that it was more excellent.

[Experimental Example 3]

<Evaluation of water contact angle of foam>

After dropping 2 ml of deionized water droplets at a height of 1 cm on each of the flat surfaces of the foams of Examples 1 to 6 and Comparative Examples 1 and 2, the time to equilibrium and the water contact angle in the equilibrium state were measured. When measuring the water contact angle, the time required to reach the equilibrium state by dropping 10 drops of deionized water randomly on the flat surface of the foam (hereinafter, stabilization time) and the water contact angle were measured, and the average value was taken.

In the case of the foams prepared in Examples 1 to 5 and Example 6, it was confirmed that the water contact angle was 0°, and the foam was completely wetted in water. Looking at the stabilization time, in the case of the foams prepared in Examples 1 to 3, the stabilization time was at a level of 2.4 to 2.8 seconds, and the stabilization time became a little shorter as the content of wheat blood increased. In the case of the foam prepared in Example 4, it was confirmed that the stabilization time had the highest hydrophilic surface property at a level of 1.2 seconds. In the case of the foam prepared in Example 5, the water contact angle was 0°, but it was confirmed that the stabilization time was significantly different (2 to 5 seconds) depending on the location where the droplet fell compared to the foam prepared in the other examples. Although it has a hydrophilic surface, it can be seen that the surface properties are non-uniform and the degree of hydrophilicity is also relatively low. In the case of Example 6, the stabilization time was 2.7 seconds, and when the relative content of corn starch compared to the resin is considered, it can be seen that the wheat blood exhibits better hydrophilic surface properties. In the case of the samples prepared in Comparative Examples 1 and 2, the contact angle was at a level of 10 to 15°.

Claims (15)

s1) preparing an extrudate by kneading and extruding a resin composition comprising a base resin and a natural material; and
s2) comprising the step of producing a foam by pressurizing the extrudate,
The natural material is a state in which the moisture content is adjusted to 0.1 to 3% by weight by a drying process,
The pressurized foaming is performed by introducing the extrudate, the blowing agent and the dispersion medium into the reactor, and controlling the pressure in the reactor,
The natural material is wheat flour, corn starch or a mixture thereof, a method for producing a foam. delete delete delete delete According to claim 1,
In step s1), the resin composition is a method of manufacturing a foam comprising 0.1 to 10 parts by weight of a natural material based on 100 parts by weight of the base resin. According to claim 1,
In step s1), the base resin is a polyolefin-based resin, a polyvinyl chloride-based resin, a polystyrene-based resin, a polyester resin, and a method for producing a foam comprising any one or two or more selected from the group consisting of copolymers thereof. According to claim 1,
Before the s1) step, the method for producing a foam further comprising the step of surface treatment of natural materials. delete According to claim 1,
In step s2), the foaming temperature during pressurized foaming is 100 to 250° C., and the foaming pressure is 0.5 to 10 Mpa. According to claim 1,
In step s2), the foaming agent is carbon dioxide, carbon monoxide, nitrogen, argon, helium, butane and a method of manufacturing a foam comprising any one or two or more physical foaming agents selected from the group consisting of pentane. According to claim 1,
The foam is a method for producing a foam for supporting microorganisms. A foam produced by the method for producing the foam of any one of claims 1, 6 to 8 and 10 to 12. 14. The method of claim 13,
The foam includes pores, the microorganisms are supported in the pores, biological water treatment foam. Claims 1, 6 to 8, and 10 to 12, characterized in that the purification by contacting the waste water with the foam produced by the method for producing the foam of any one of claims 10 to 12, waste water using the foam purification method.

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