2-ethylhexanol adsorbent and adsorption method therefor

Abstract

To determine 2-ethylhexanol and its derivatives as odor components specific to paper, and effectively adsorb and remove these odor components.SOLUTION: The present invention provides a 2-ethylhexanol adsorbent, comprising a silica-magnesia composite particle formed by integrating silicon dioxide (SiO2) and magnesium oxide (MgO). The BET surface area ratio (H2O / N2), which is the ratio of the BET surface area measured by water vapor adsorption to the BET surface area measured by nitrogen adsorption, is 0.4 to 0.9.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an adsorbent that adsorbs and removes 2-ethylhexanols, which are substances that cause paper odor, and a method for adsorbing 2-ethylhexanols. [Background technology]

[0002] In recent years, efforts to reduce the use of plastics have been progressing worldwide, and the demand for paper products has been increasing. However, paper has a unique odor, which has been a problem in food and beverage applications. That is, if the odor unique to paper is absorbed into food and beverages served in paper products for food and beverages, such as paper containers (paper plates, paper cups, paper bags, paper containers) and paper filters (coffee filters, filter paper), the flavor may be impaired. For example, if odorous components are dissolved in drinking water filtered through a paper filter, the person consuming it may feel uncomfortable. The unique odor of paper is caused by the odor derived from natural materials (raw wood) and the odor derived from chemicals added in pulp production.

[0003] Patent Document 1 discloses a food container packaging material having a multi-layer structure including paper and a thermoplastic resin layer, in which a polyolefin resin layer between the paper and the innermost resin layer contains a mixture of MgO and SiO2 as an inorganic porous active material. The food container packaging material of Patent Document 1 prevents the odor of the paper from transferring to the food.

[0004] Patent Document 2 discloses a trigonelline adsorbent consisting of silica-magnesia composite particles in which silica particles and magnesia particles are integrally composited, and having an anion adsorption capacity, expressed as Orange II adsorption amount, of 18 to 74 mmol / 100 g.

[0005] Patent Document 3 discloses an adsorbent for lignin and vanillin, which contains silica-magnesium oxide composite particles in which silica particles and magnesium oxide particles are integrally composited together. The adsorbent of Patent Document 3 is used as a pitch control agent in pulp production, or by being incorporated into or coated on paper.

[0006] The food container packaging material of Patent Document 1 contains a mixture of MgO and SiO2 as an inorganic porous active substance, but does not contain composite particles that combine these together. In other words, Patent Document 1 shows a mixture in which the two substances are simply mixed together without any bonding, but does not show composite particles that are integrated through the process of homogenous mixing, aging, moisture removal, and baking. In addition, Patent Document 1 shows an odor adsorption and removal effect, but does not specify the specific components that cause odor, and the adsorption and removal effect is judged only by a sensory test, without disclosing the results of objective quantitative tests.

[0007] The trigonelline adsorbent in Patent Document 2 is composed of silica-magnesia composite particles, but its sole purpose is to adsorb trigonelline, which is contained in coffee beans and some seafood, and it is not intended to adsorb paper odors.

[0008] The adsorbent in Patent Document 3 uses silica-magnesium oxide composite particles to solve the problem of odors specific to paper products, but Patent Document 3 indicates that lignin and vanillin derived from raw wood are to be adsorbed, and does not target components derived from chemicals added in pulp production. In terms of the odor specific to paper, components derived from chemicals added are generally more toxic and irritating than components derived from natural substances (lignin and vanillin), and their removal is therefore more important. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 6-340036 [Patent Document 2] Patent Publication No. 2020-179334 [Patent Document 3] Patent Publication No. 2023-71002 Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, in the present invention, 2-ethylhexanol and its derivatives are identified as odorous components specific to paper, and an object of the present invention is to provide an adsorbent for 2-ethylhexanols and an adsorption method thereof that can effectively adsorb and remove these odorous components. [Means for solving the problem]

[0011] The adsorbent for 2-ethylhexanols of the present invention is a silica-magnesia composite particle in which silicon dioxide (SiO2) and magnesium oxide (MgO) are integrated, and has a BET specific surface area ratio (H2O / N2), which is the ratio of the BET specific surface area measured by the water vapor adsorption method to the BET specific surface area measured by the nitrogen adsorption method, of 0.4 to 0.9. The present invention exhibits a higher adsorption function for 2-ethylhexanol and its derivatives (hereinafter referred to as "2-ethylhexanols"), which are added chemicals during pulp production, compared to the conventional silica-magnesia mixture or silica alone. The adsorption mechanism of the present invention is physical adsorption by pores, and compared to the conventional technology, the present invention has a larger pore volume available for adsorption, a smaller BET specific surface area ratio, and is hydrophobic, so that adsorption is less likely to be inhibited by the solvent (water). The adsorption target substance, 2-ethylhexanol, is almost insoluble in water and has the property of separating from water and coagulating (hydrophobic effect), so the adsorbent of the present invention, which has hydrophobic properties, can efficiently adsorb trace amounts of 2-ethylhexanol in water by coagulating it. Furthermore, a derivative of 2-ethylhexanol has a 2-ethylhexyl group "-CH2CH(C2H5)CH2CH2CH2CH3", which is a strong hydrophobic group that does not contain a hydroxyl group (-OH), and is a long-chain alkyl group that occupies most of the derivative molecule, and is greatly influenced by its hydrophobicity. Therefore, compared to 2-ethylhexanol, the derivative has a higher hydrophobic effect and is more likely to coagulate in water, and is considered to be able to exhibit extremely high adsorption ability. Therefore, in the present invention, the adsorption function of 2-ethylhexanols is extremely high, and paper produced using the adsorbent of the present invention does not emit the characteristic unpleasant odor.

[0012] In the method for adsorbing 2-ethylhexanols of the present invention, the adsorbent is added to an aqueous solution containing 2-ethylhexanols to adsorb the 2-ethylhexanols. Alternatively, the adsorbent is impregnated into paper as a final product by coating, spreading, spraying, or immersion to adsorb the 2-ethylhexanols. Effect of the Invention

[0013] The 2-ethylhexanol adsorbent and adsorption method of the present invention can highly efficiently adsorb 2-ethylhexanol, which is the cause of paper odor, as a target substance, making it possible to produce paper products in which the generation of unpleasant odors is suppressed, and by maintaining the deodorizing and odor eliminating effects, it is possible to effectively prevent odors from adhering to food and beverages from the paper products. [Brief description of the drawings]

[0014] [Figure 1] Graph showing the relationship between BET specific surface area ratio and 2-ethylhexanol adsorption rate [Diagram 2] Graph showing the relationship between pore volume and 2-ethylhexanol adsorption rate DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The following describes an embodiment of the adsorbent for 2-ethylhexanols and the adsorption method thereof according to the present invention. The following embodiment is merely an example and is not to be construed as limiting the present invention.

[0016] The 2-ethylhexanol adsorbent of the present invention (hereinafter referred to as "2-EH adsorbent") is a silica-magnesia composite particle in which silicon dioxide (SiO2) and magnesium oxide (MgO) are integrated. Since it is a composite particle made of silicon dioxide (silica) and magnesium oxide (magnesia), which are approved as food additives, the 2-EH adsorbent of the present invention can be safely applied to paper products for food and beverage use, and has a wider range of applications and is superior to, for example, known high-silica zeolites (zeolites with SiO2 / Al2O3 of 10 or more).

[0017] The substance to be adsorbed (adsorbed substance), 2-ethylhexanol, is also called "2-ethyl-1-hexanol," "2-ethylhexyl-1-ol," "2-ethylhexyl alcohol," or "octanol," and its chemical structural formula is shown in formula (1) below. [ka]

[0018] 2-Ethylhexanol, which is liquid at room temperature (melting point -76°C, boiling point 183-185°C), is generally used as an organic solvent and as a defoaming agent in the pulp manufacturing process. Table 1 shows the results of gas chromatography-mass spectrometry (GC-MS) analysis of 2-ethylhexanol components in various commercially available coffee paper filters, qualitative filter papers, and quantitative filter papers (Food Analysis Development Center, a non-profit organization). It can be seen from Table 1 that 2-ethylhexanol was strongly detected in the commercially available coffee paper filters, and even more strongly detected in the various commercially available qualitative and quantitative filter papers. [Table 1]

[0019] 2-Ethylhexanol is irritating to the eyes, respiratory tract, skin, etc., and may cause nausea, headache, diarrhea, and vomiting when inhaled or ingested. Although the concentration of 2-ethylhexanol in paper products is low, it is difficult to say that it is safe for the human body if inhaled or ingested for a long period of time, or if the paper products are used for high-temperature food and drink and 2-ethylhexanol evaporates. Therefore, by using the 2-EHs adsorbent of the present invention, it is possible to provide paper products for food and drink (paper containers, paper filters, etc.) that are safe for the human body.

[0020] The 2-ethylhexanols as the substances to be adsorbed in the present invention are one or more selected from 2-ethylhexanol and 2-ethylhexanol derivatives, and the 2-EHs adsorbent is considered to exhibit the same adsorption characteristics as 2-ethylhexanol for 2-ethylhexanol derivatives having a 2-ethylhexyl group. The 2-ethylhexanol derivatives include bis(2-ethylhexyl)phthalate (DEHP, DOP) shown in the following formula (2), bis(2-ethylhexyl)adipate (DEHA, DOA) shown in the following formula (3), and 2-ethylhexyl acrylate shown in the following formula (4). [ka] [ka] [ka]

[0021] The 2-ethylhexanol derivatives to be adsorbed include 2-ethylhexyl derivatives having a 2-ethylhexyl group, such as bis(2-ethylhexyl) sebacate, bis(2-ethylhexyl) azelaate, tris(2-ethylhexyl) trimellitate, and bis(2-ethylhexyl) 4-cyclohexene-1,2-dicarboxylate.

[0022] The 2-EHs adsorbent according to the present invention preferably has a BET specific surface area ratio (H2O / N2) of 0.4 to 0.9, which is the ratio of the BET specific surface area measured by the water vapor adsorption method to the BET specific surface area measured by the nitrogen adsorption method. When the 2-EHs adsorbent according to the present invention has a BET specific surface area ratio of less than 0.4, it is excessively hydrophobic and does not disperse in an aqueous solution, resulting in insufficient adsorption ability, but when it is 0.4 or more, it has moderate hydrophilicity and disperses well, resulting in sufficient adsorption ability. When the BET specific surface area ratio is 0.9 or less, it can exhibit high adsorption ability due to moderate hydrophobicity. More preferably, it is 0.6 to 0.8, and even more preferably, it is 0.61 to 0.71. In the present invention, when the BET specific surface area ratio is within these ranges, it exhibits high adsorption performance for 2-ethylhexanol and its derivatives. Specifically, when the BET specific surface area ratio is 0.4 to 0.9, the adsorption rate is 30 to 50%. The present invention exhibits higher adsorption performance than conventional techniques such as acid clay, activated clay, silica alone, and mixtures of silica and magnesia.

[0023] The adsorbent for 2-EHs according to the present invention also has a pore volume of 0.5 to 1.5 cm when the pore diameter is 20 to 1200 angstroms. 3 / g. From the viewpoint of preventing clogging and rapidly absorbing the 2-ethylhexanol-containing aqueous solution, the 3 / g or more is preferable, and 1.5 cm 3 / g or less, more preferably 0.7 to 1.4 cm 3 / g, more preferably 0.8 to 1.2 cm 3 / g. In the present invention, when the pore volume is in this range, high adsorption performance for 2-ethylhexanol and its derivatives is exhibited. Specifically, when the pore volume is 0.5 to 1.5 cm 3 / g, the adsorption rate is 30 to 50%.

[0024] The method for producing the 2-ethylhexanol adsorbent (2-EH adsorbent) will be described in detail below. First, in the homogeneous mixing step, silicon dioxide particles and magnesium oxide particles are put into water and homogeneously mixed to dissolve the silicon dioxide particles into colloidal particles and fine aggregated particles (primary and secondary particles), and the magnesium oxide particles are surface-hydrated to form fine particles of magnesium oxide and its hydrate, forming a slurry in which these particles are homogeneously dispersed in water. Next, in the aging step, water is removed from the slurry to increase the solid concentration, and the silicon dioxide particles and magnesium oxide particles are brought close to each other to form composite particles that are physically integrated without chemical bonding. The homogeneous mixing step and the aging step are carried out at 50 to 79°C with stirring.

[0025] In the next moisture removal step, the composite particles are dried in a dryer at 110 to 200°C to remove the hydration of magnesium oxide, and in the firing step, the composite particles are fired in a firing furnace at 550 to 750°C to increase the particle strength, thereby obtaining silica-magnesia composite particles (2-EHs adsorbent) of the present invention in which silicon dioxide particles and magnesium oxide particles are closely composited. If necessary, the particles are pulverized, classified, and molded to have a particle size and shape suitable for adsorbing 2-ethylhexanols. The average particle size of the 2-EHs adsorbent is 5 to 500 μm, preferably 7.5 to 200 μm.

[0026] Hereinafter, an embodiment of the method for adsorbing 2-ethylhexanols according to the present invention will be described in detail. The 2-EH adsorbent of the present invention is added to an aqueous solution containing 2-ethylhexanols to adsorb the 2-ethylhexanols. The aqueous solution containing 2-ethylhexanols is, for example, a pulp dissolving solution in papermaking. In the pulp production process before the papermaking process, the 2-EH adsorbent is added to the pulp dissolving solution and uniformly dispersed in the pulp dissolving solution by stirring or the like. This allows the 2-EH adsorbent to penetrate into the interior of the pulp fibers, resulting in a high deodorizing effect. Below, the pulp production process and the timing of adding the 2-EH adsorbent are explained.

[0027] In the pulp manufacturing process of papermaking, first, raw material wood chips are put into a digester and treated with caustic soda or the like at high temperature and high pressure (digestion) to generate a pulp-dissolving solution, and then impurities such as lignin are removed from the pulp-dissolving solution using a washer (washing). Further, foreign matter such as wood chips is removed from the pulp-dissolving solution (screening), and the pulp is treated with a bleaching agent such as chlorine dioxide or hydrogen peroxide (bleaching). In the pulp manufacturing process, foaming and fine bubbles are generated due to the resin content (pitch) decomposed and extracted from the wood chips, and due to the concentration of foaming substances caused by the reuse of filtered water (white water) in the papermaking process, which causes problems such as poor dehydration in the washer, reduced productivity, and deterioration of the quality of paper products. Therefore, a defoamer (foam suppressor, foam breaker) containing 2-ethylhexanol or its derivatives is added to the pulp-dissolving solution in advance (generally during the washing process). However, 2-ethylhexanol and its derivatives remain and cause the odor peculiar to paper. Therefore, in this embodiment, the 2-EHs adsorbent of the present invention is added to the pulp dissolving solution before the next papermaking process. The addition of the 2-EHs adsorbent may be done before, after, or simultaneously with the addition of the defoaming agent, so long as it is done before the papermaking process.

[0028] In the papermaking process, the bleached pulp is spread on a papermaking wire in the wire part to form a fiber sheet, which is then dehydrated, the water is squeezed out of the sheet in the press part, the sheet is dried in the dryer part, and the final paper product is produced by further surface treatment, etc. The produced paper retains the 2-EH adsorbent to an extent that does not affect the quality, has the odor of 2-ethylhexanol removed, and maintains its deodorizing effect.

[0029] Instead of adding the 2-EH adsorbent to the pulp dissolving solution in the pulp manufacturing process, the 2-EH adsorbent or its solution may be impregnated and retained in the final paper product by coating, spreading, spraying or immersion. This makes it possible to prevent the 2-EH adsorbent from being removed during the papermaking process and allows the 2-EH adsorbent to be retained in the paper efficiently and without waste.

[0030] The 2-EH adsorbent may not be retained in the final paper product as in the above embodiment. In another embodiment, a liquid or gas containing 2-ethylhexanols may be passed through an adsorption device filled with a 2-EH adsorbent to continuously adsorb the 2-ethylhexanols. Alternatively, a batch-type (batch-type) adsorption treatment may be performed in which the 2-EH adsorbent is added to a liquid containing 2-ethylhexanols and stirred, and the 2-EH adsorbent is removed after the treatment. The used 2-EH adsorbent that has reached the breakthrough point in the above continuous or batch-type adsorption treatment may be replaced with an unused one, or the 2-ethylhexanols may be desorbed using, for example, hot water, an acid, an alkali, an organic solvent, or the like, by backwashing, or by reduced pressure treatment, to regenerate and reuse the 2-EH adsorbent. EXAMPLES

[0031] Examples (the present invention) and comparative examples (prior art) will be compared below.

[0032] [2-EH adsorbent particles of the present invention (Examples 1 to 4)] 2-EHs adsorbent particles having mass ratios (Sm / Mm) of the magnesium oxide content Mm [mass%] converted to MgO to the silicon dioxide content Sm [mass%] converted to SiO2 of 2.00, 1.69, 1.64 and 2.03 were prepared, and designated as Examples 1, 2, 3 and 4, respectively.

[0033] [Adsorbent particles of the prior art (Comparative Examples 1 to 3)] Adsorbent particles of acid clay (manufactured by Mizusawa Chemical Industry Co., Ltd.), activated clay (manufactured by Mizusawa Chemical Industry Co., Ltd.), and silica (manufactured by Mizusawa Chemical Industry Co., Ltd.) were prepared and designated as Comparative Examples 1, 2, and 3, respectively.

[0034] [Test 1: BET specific surface area ratio] The 2-EH adsorbent particles of Example 1 were measured for the BET specific surface area [m 2 / g] was measured and calculated, and the BET specific surface area [m 2The BET specific surface area ratio (H2O / N2) was calculated from each BET specific surface area. The BET specific surface area ratio was calculated for each of the adsorbent particles of Examples 2 to 4 and Comparative Examples 1 to 3 by the same method as above.

[0035] [Test 2: Pore volume] The BET specific surface area [m 2 / g] and the pore volume [cm 3 / g](=(average pore diameter [m] × BET specific surface area [m 2 / g]×10 6 ) / 2) was calculated.

[0036] [Test 3: 2-Ethylhexanol adsorption rate] 0.8 g of the 2-EH adsorbent particles of Example 1 was added to 25 g of 2-ethylhexanol test liquid prepared to 20 ppm using water as a solvent, and the mixture was shaken at room temperature for 2 hours. Next, the amount of 2-ethylhexanol remaining in the liquid obtained by solid-liquid separation using a centrifuge was measured using a gas chromatograph measuring device (GC-2014, Shimadzu Corporation), and the 2-ethylhexanol adsorption rate [%] (= (amount of component input-amount of component remaining) x 100 / amount of component input) was calculated. Using the same method as above, the 2-ethylhexanol adsorption rate [%] was calculated for each of the adsorbent particles of Examples 2 to 4 and Comparative Examples 1 to 3.

[0037] [Test results and discussion] The results of the test methods for each of the adsorbent particles in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in the table below. [Table 2]

[0038] Based on the test results shown in Table 2, the relationship of 2-ethylhexanol adsorption rate (vertical axis) to BET specific surface area ratio (horizontal axis) is shown in Figure 1. As shown in Figure 1, in Examples 1 to 4 using the 2-EHs adsorbent particles of the present invention, a high adsorption rate of 29.9 to 47.4% was achieved in the range of BET specific surface area ratios of 0.61 to 0.71. As shown in Figure 1, it is considered that the 2-EHs adsorbent particles of the present invention have a high adsorption rate not only in the above range but also at least up to about 0.4 to 0.9 with respect to the BET specific surface area ratio. On the other hand, in Comparative Examples 1 to 3 using the adsorption particles of acid clay, activated clay, and silica of the prior art, a low adsorption rate of 0 to 10% was achieved in the range of BET specific surface area ratios of 0.95 to 2.60.

[0039] Based on the test results shown in Table 2, the relationship between the pore volume (horizontal axis) and the 2-ethylhexanol adsorption rate (vertical axis) is shown in Figure 2. As shown in Figure 2, in Examples 1 to 4 using the 2-EHs adsorbent particles of the present invention, the pore volume was 0.8 to 1.2 cm 3 2, the adsorption rate was high at 29.9 to 47.4% in the range of 0.5 to 1.5 cm3 / g. 3 / g. On the other hand, in Comparative Examples 1 to 3 using the conventional adsorption particles of acid clay, activated clay, and silica, the pore volume was 0.3 to 0.5 cm3. 3 / g, the low adsorption rate was 0 to 10%, as described above.

[0040] [Conclusion] 1, it was found that the 2-EHs adsorbent particles of the present invention (Examples 1 to 4) had a high adsorption rate for 2-ethylhexanol when the BET specific surface area ratio was in the range of 0.61 to 0.71, and the adsorption rate was high up to about 0.4 to 0.9. Also, from FIG. 2, it was found that the 2-EHs adsorbent particles of the present invention (Examples 1 to 4) had a high adsorption rate for 2-ethylhexanol when the BET specific surface area ratio was in the range of 0.8 to 1.2 cm. 3 / g, 2-ethylhexanol has a high adsorption rate, and the adsorption rate is in the range of 0.5 to 1.5 cm 3 It was found that the adsorption rate was as high as about 1 / g. [Industrial Applicability]

[0041] By impregnating not only paper products but also threads, fibers, cloth, building materials, interior materials, paints, etc., with the 2-EH adsorbent particles, the deodorizing function of the present invention can be exerted in the fields of apparel, medicine, construction, automobiles, etc. In addition, it can be used for purifying gases, liquids, and soils contaminated with 2-ethylhexanols in the fields of air purification, wastewater treatment, soil improvement, oil refining, etc.

Claims

1. Silica-magnesia composite particles in which silicon dioxide and magnesium oxide are integrated, An adsorbent for 2-ethylhexanols, characterized in that a BET specific surface area ratio, which is a ratio of a BET specific surface area measured by a water vapor adsorption method to a BET specific surface area measured by a nitrogen adsorption method, is 0.4 to 0.

9.

2. The adsorbent for 2-ethylhexanols according to claim 1, wherein the 2-ethylhexanols as the substances to be adsorbed are one or more selected from the group consisting of 2-ethylhexanol, bis(2-ethylhexyl) phthalate, bis(2-ethylhexyl) adipate, and 2-ethylhexyl acrylate.

3. Pore ​​volume is 0.5 to 1.5 cm 3 The adsorbent for 2-ethylhexanol according to claim 1, wherein the adsorbent has a molecular weight of 2-ethylhexanol / g.

4. 13. An adsorption method comprising adding the adsorbent according to claim 1 to an aqueous solution containing 2-ethylhexanols to adsorb the 2-ethylhexanols.

5. The aqueous solution containing 2-ethylhexanols is a pulp dissolving solution, The method for adsorption according to claim 4, wherein the adsorbent is added to a pulp dissolving solution prior to a papermaking process.

6. 13. An adsorption method comprising impregnating a paper as a final product with the adsorbent according to claim 1 by coating, spreading, spraying or immersion to adsorb 2-ethylhexanols.

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