Adsorbent for lignin and vanillin containing magnesium oxide particles

Abstract

To provide an adsorbent capable of removing odor derived from lignin and vanillin which is used as a pitch control agent in a pulp manufacturing step, or alternatively used by being embedded in or applied to paper.SOLUTION: The present invention is an adsorbent of lignin and vanillin which contains at least magnesium oxide particles.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adsorbent for lignin and vanillin containing magnesium oxide particles, and more particularly to an adsorbent containing magnesium oxide particles used to remove lignin and vanillin, which are causes of odor in paper products. [Background technology]

[0002] Pulp, the main raw material for paper, is typically produced by alkaline cooking, in which raw wood chips are boiled under high temperature and pressure with the addition of caustic soda or the like. Wood contains 20 to 30% by weight of lignin, a polymeric compound whose basic unit is hydroxypropane, in the lignified plant matter. If lignin remains in the pulp, it can cause a decrease in paper strength and discoloration. Furthermore, during alkaline cooking or enzymatic treatment after alkaline cooking, a portion of the lignin is decomposed to produce vanillin (4-hydroxy-3-methoxybenzaldehyde). Lignin and vanillin each have their own distinctive odors, and while most can be removed by washing the pulp, completely removing them has proven difficult.

[0003] In order to promote and increase the efficiency of the removal of lignin, it is known to carry out alkaline cooking by adding a cooking aid such as an aldehyde compound, ethanolamine, a quinone compound, or a cyclic keto compound in addition to caustic soda (Patent Documents 1 and 2).

[0004] However, even when alkaline cooking is performed with the addition of the cooking aid, it cannot be said that the lignin and vanillin in the pulp are sufficiently removed, and there is a problem that paper products such as paper containers for food, such as paper cups and paper plates, and paper filters used for drip coffee, have a characteristic odor derived from lignin and vanillin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 51-043403 [Patent Document 2] Japanese Patent Publication No. 52-037803 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, an object of the present invention is to provide an adsorbent that is used as a pitch control agent in the pulp production process, or that is incorporated into or coated on paper, and that is capable of removing the characteristic odors derived from lignin and vanillin. Here, the pitch control agent refers to a general chemical that suppresses pitch adhesion problems during the papermaking process caused by the resin content (pitch) contained in wood or waste paper, which are the raw materials for paper.

[0007] Another object of the present invention is to provide a method for adsorbing lignin and vanillin in a pulp production process, comprising adding an adsorbent to a liquid to adsorb lignin and vanillin, and then separating the adsorbent from the liquid by filtration.

[0008] Furthermore, another object of the present invention is to provide a method for reducing the amount of lignin and vanillin leaching, in which a paper product holds an adsorbent, which adsorbs lignin and vanillin that leach out from the paper product when the paper product comes into contact with a liquid, thereby reducing the amount of leaching. [Means for solving the problem]

[0009] According to the present invention, there is provided an adsorbent for lignin and vanillin, which comprises at least magnesium oxide particles.

[0010] The magnesium oxide particles are preferably baked magnesium hydroxide.

[0011] It is preferred that the adsorbent contains only magnesium oxide particles.

[0012] The adsorbent preferably contains only silica-magnesium oxide composite particles in which silica particles and magnesium oxide particles are integrally composited together.

[0013] According to the present invention, there is provided a method for adsorbing lignin and vanillin, for example, in a pulp production process, in which the adsorbent is added to a liquid to adsorb lignin and vanillin, and then the adsorbent is separated from the liquid by filtration. Here, the method for adsorbing lignin and vanillin means a method for adsorbing lignin and a method for adsorbing vanillin, and includes an adsorption method in which both lignin and vanillin are present in the liquid, and an adsorption method in which only one of lignin and vanillin is present in the liquid.

[0014] According to the present invention, there is provided a method for reducing the amount of lignin and vanillin eluted, in which a paper product retains the adsorbent, and the adsorbent adsorbs lignin and vanillin that elutes from the paper product when the paper product comes into contact with a liquid, thereby reducing the amount of elution. Here, retaining the adsorbent in a paper product means that the adsorbent is incorporated into paper products such as paper containers for food, such as paper cups and paper plates, or paper filters used for drip coffee, or the adsorbent is applied in the form of a paste and retained in the paper product. Furthermore, the method for reducing the amount of eluted lignin and vanillin means a method for reducing the amount of eluted lignin and a method for reducing the amount of eluted vanillin, and includes a method for reducing the amount of eluted lignin when both lignin and vanillin are present in the liquid, and a method for reducing the amount of eluted lignin when only one of lignin and vanillin is present in the liquid. [Effects of the Invention]

[0015] The present invention relates to an adsorbent for lignin and vanillin containing at least magnesium oxide particles, which is used as a pitch control agent in the pulp production process, particularly in the alkaline cooking process, the washing process after alkaline cooking, and the subsequent enzyme treatment and bleaching process in the papermaking process, and which is also used by being incorporated into paper itself or by being applied in the form of a paste.Paper products made from pulp using the adsorbent of the present invention, such as paper food containers such as paper cups and paper plates, and paper filters used for drip coffee, have the characteristic odors derived from lignin and vanillin suppressed, making it possible to enjoy the aroma and flavor of beverages such as sake and juice, and food ingredients such as grilled meat and vegetables at a barbecue without impairing them, and also without impairing the rich aroma and flavor of drip coffee.

[0016] The adsorbent for lignin and vanillin containing the magnesium oxide particles of the present invention can remove at least 80% or more of lignin and 40% or more of vanillin, preferably 90% or more of lignin and 70% or more of vanillin, more preferably 90% or more of both lignin and vanillin, and particularly preferably 95% or more of both lignin and vanillin. DETAILED DESCRIPTION OF THE INVENTION

[0017] The adsorbent of the present invention contains at least magnesium oxide particles, and may contain only magnesium oxide particles, may contain only silica-magnesium oxide composite particles in which silica particles and magnesium oxide particles are integrally composited, or may contain magnesium oxide particles and silica-magnesium oxide composite particles.

[0018] One advantage of the particulate form of the adsorbent of the present invention is that, while there is a possibility of environmental problems arising if the adsorbent is added to the alkaline cooking liquor or washing liquor in pulp production processes such as the alkaline cooking step and the subsequent water washing step to adsorb lignin and vanillin and then released outside together with the waste liquid, because the adsorbent is in particulate form, it can be easily separated from the waste liquids such as the alkaline cooking liquor and washing liquor by filtering using filter paper or the like, thereby easily avoiding environmental problems.

[0019] The adsorbent of the present invention can be incorporated into paper products such as paper containers for food, such as paper cups and paper plates, or paper filters used for drip coffee, or coated in the form of a paste, so that the adsorbent is retained in the paper product. When the paper product comes into contact with a liquid, there is a possibility that lignin and vanillin remaining in the paper product will be eluted. In this case, the adsorbent retained in the paper product itself adsorbs the lignin and vanillin, thereby reducing the amount of elution and, as a result, reducing the characteristic odor.

[0020] <Adsorbent containing only magnesium oxide particles> The magnesium oxide particles used as an adsorbent in the present invention can be obtained by various methods, such as by calcining magnesium hydroxide or magnesium carbonate, but the most suitable magnesium oxide is obtained by calcining magnesium hydroxide. When magnesium oxide is produced by such a method, decomposition does not occur. Therefore, by adjusting the calcination temperature within a certain range, it is possible to easily obtain magnesium oxide having a consistent BET specific surface area and pore distribution suitable for adsorbing lignin and vanillin.

[0021] For example, in the present invention, a material that exhibits high adsorption performance for lignin and vanillin has a BET specific surface area of ​​10 m 2 / g or more, preferably 100m 2 / g or more, particularly preferably 150m 2 / g or more, 500m 2 / g or less, and the pore diameter is in the range of 17 to 1000 Å, and the pore volume is preferably 0.10 cm 3 / g or more, particularly preferably 0.20 cm 3 / g or more. In particular, in the region of 17 to 100 Å, the 3 / g or more. Magnesium oxide particles having such a BET specific surface area and pore volume distribution can be obtained by calcining magnesium hydroxide at 200°C to 1100°C. The calcination temperature is preferably 250°C or higher, more preferably 350°C or higher, and preferably 1050°C or lower, more preferably 800°C or lower, and particularly preferably 400 to 500°C. The magnesium oxide particles described above can be obtained by utilizing the fact that the higher the calcination temperature, the greater the BET specific surface area and pore volume.

[0022] In the present invention, the most suitable magnesium oxide particles are those obtained by firing at 400 to 500°C, and the pore volume value when the pore diameter is 17 to 1000 Å is 0.10 cm 3 / g or more, and the pore volume value for 17 to 100 Å is 0.01 cm 3 / g or more, and the BET specific surface area is 120m 2 / g. Such magnesium oxide particles have strong adsorption selectivity for lignin and vanillin and are used as an adsorbent for lignin and vanillin in the form of granules with an appropriate particle size.

[0023] <An adsorbent containing only silica-magnesium oxide composite particles, which are an integrated composite of silica particles and magnesium oxide particles> The silica-magnesium oxide composite particles used as an adsorbent in the present invention are formed from a silica component and a magnesium oxide component, both of which are approved as adsorbents and filter aids for food production. stomach do.

[0024] Silica-magnesium oxide composite particles can be obtained by homogeneously mixing silica (A) and magnesium oxide or its hydrate (B) in the presence of water to form an aqueous slurry (homogeneous mixing), followed by aging and then removing the water.

[0025] In a specific method for producing silica-magnesium oxide composite particles, silica (silicon dioxide), one of the raw materials, is dissolved into colloidal particles or finely aggregated particles (primary and secondary particles) in the presence of moisture, for example, by homogeneous mixing in water. On the other hand, when magnesium oxide is added to water and stirred or crushed, it hardly dissolves, but due to partial hydration of the surface of the magnesium oxide particles, some or all of the crystals (or newly formed hydrate crystals) collapse or peel off, resulting in fine particles of magnesium oxide and / or magnesium oxide hydrate that are dispersed in water. In this way, an aqueous slurry with fine particles homogeneously dispersed is obtained.

[0026] Next, in the aging process, water is removed from the slurry in which these fine particles are uniformly dispersed, and as the solids concentration increases, the silica particles (A) and magnesium oxide particles (B) gradually or suddenly approach each other, and reach a composite structure without chemical bonding such as atomic exchange or recombination (completion of composite structure). In other words, the silica-magnesium oxide composite particles of the present invention have a structure that is integrated so that they cannot be separated by physical means.

[0027] In the present invention, the mass ratio of the silica component to the magnesium oxide component may be appropriately determined so that the desired adsorption capacity for lignin or vanillin is fully exhibited. For example, the proportion of magnesium oxide may be 5% by mass or more, and preferably 20% by mass or more. [Example]

[0028] The present invention will be described in more detail below with reference to examples. Measurement methods in the examples are as follows.

[0029] (1) BET specific surface area by nitrogen adsorption method Measurements were performed by nitrogen adsorption using a Micromeritics TriStar 3000, and calculations were performed by the BET method. Pretreatment was performed at 150°C for 2 hours.

[0030] (2) Lignin and vanillin adsorption test In this example, the lignin and vanillin adsorption capacity was defined as the percentage (%) of the amount of lignin or vanillin that 1 g of a sample (in an anhydrous state) could adsorb from a 0.2 g / L aqueous solution of lignin or vanillin, and was measured and calculated by the following method. First, lignin (manufactured by Tokyo Chemical Industry Co., Ltd.) and vanillin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were dissolved in 1 L of ion-exchanged water to obtain an aqueous solution of lignin or vanillin with a concentration of 0.2 g / L. 30 g of this 0.2 g / L lignin or vanillin aqueous solution was weighed into a 50 ml centrifuge tube, and 1 g (3.3% by mass relative to the liquid) of adsorbent sample was added, followed by shaking for 2.5 hours using a shaker (SA300, manufactured by Yamato Scientific Co., Ltd., shaking speed 5). Next, the mixture was centrifuged at 3500 rpm for 20 minutes using a centrifuge (5200 manufactured by Kubota Corporation), and the supernatant was used as the sample solution. The lignin concentration of the sample solution was calculated using a calibration curve showing the relationship between lignin concentration and absorbance of 400 nm wavelength light. The vanillin concentration of the sample solution was calculated using a calibration curve showing the relationship between vanillin concentration and absorbance of 230 nm wavelength light. From these values, the lignin adsorption rate and vanillin adsorption rate per unit mass of sample were calculated.

[0031] Table 1 shows the lignin adsorption rate and vanillin adsorption rate for the adsorbents shown in Experimental Examples 1 to 5 and Comparative Examples 1 to 6 below.

[0032] (Experimental Example 1) This adsorbent contains only magnesium oxide particles, obtained by calcining commercially available magnesium hydroxide at 450°C for 1 hour. (BET specific surface area: 177 m 2 / g)

[0033] (Experimental Example 2) Adsorbent containing only magnesium oxide particles (BET specific surface area = 120 m 2 / g)

[0034] (Experimental Example 3) Adsorbent containing only magnesium oxide particles (BET specific surface area = 2m2 / g)

[0035] (Experimental Example 4) Adsorbent containing only magnesium oxide particles (BET specific surface area = 10 m 2 / g)

[0036] (Experimental Example 5) An adsorbent containing only composite particles of silica and magnesium oxide as described in Experimental Example 2 (magnesium oxide content: 33% by mass).

[0037] (Comparative Example 1) Magnesium silicate manufactured by Mizusawa Industrial Chemicals Co., Ltd.

[0038] (Comparative Example 2) Zinc aluminosilicate manufactured by Mizusawa Industrial Chemicals Co., Ltd.

[0039] (Comparative Example 3) High silica zeolite (MFI type) manufactured by Mizusawa Industrial Chemicals Co., Ltd.

[0040] Comparative Example 4 Silica manufactured by Mizusawa Industrial Chemicals Co., Ltd.

[0041] (Comparative Example 5) Activated clay manufactured by Mizusawa Industrial Chemicals Co., Ltd.

[0042] (Comparative Example 6) Bentonite manufactured by Mizusawa Industrial Chemicals Co., Ltd.

[0043] [Table 1]

Claims

1. An adsorbent for lignin and vanillin, which is used as a pitch control agent in the pulp manufacturing process, or is incorporated into or coated on paper, characterized by containing at least magnesium oxide particles.

2. 2. The adsorbent according to claim 1, wherein the magnesium oxide particles are calcined magnesium hydroxide.

3. The adsorbent according to any one of claims 1 to 2, which contains only magnesium oxide particles.

4. The adsorbent according to any one of claims 1 and 2, which contains only silica-magnesium oxide composite particles in which silica particles and magnesium oxide particles are integrally composited together.

5. A method for adsorbing lignin and vanillin, comprising adding the adsorbent according to any one of claims 1 to 4 to a liquid as a pitch control agent in a pulp production process, adsorbing lignin and vanillin, and then separating the adsorbent from the liquid by filtration.

6. A method for reducing the amount of lignin and vanillin eluted, comprising incorporating the adsorbent according to any one of claims 1 to 4 into a paper product or applying it to the paper product, and adsorbing lignin and vanillin eluted from the paper product when the paper product comes into contact with a liquid, thereby reducing the amount of elution.

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