Deodorant and method for producing deodorant

Abstract

A deodorant using, as a raw material, biomass derived from silicic acid plants such as rice husks, rice straws, and wheat straws, the biomass derived from silicic acid plants fed into a gasifier (10) being gasified by high-temperature water vapor and air, the deodorant comprising a composite in which the content of amorphous silica is 50-100 wt% and the content of carbon is 0-50 wt%, it is preferable that an acid site is present on the surface of the amorphous silica through an acid treatment step, or that an alkali site is present on the surface of the amorphous silica through an alkali treatment step.

Description

Technical Field

[0001] The present invention relates to a deodorant using biomass derived from silicic acid plants such as rice husks as a raw material and a method for producing the deodorant. Background Art

[0002] Patent Document 1 discloses an oil or gas adsorbent obtained by continuously carbonizing organic wastes derived from plants or animals using a kiln. Patent Document 1 also discloses the following content: As the raw material to be carbonized, organic matter derived from plants or animals is used, specifically, coffee bean residues, plum seeds, bean residues, cow dung, pig dung, sludge, rice husks, paulownia tomentosa or fir thinnings, sawdust, and other organic raw materials are used, and among the raw materials derived from plants, rice husks, paulownia tomentosa, and cedar are more preferably used.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6431469 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In recent years, solving the problem of global warming has become an urgent issue, and countries around the world are promoting the transition to renewable energy as a measure to help decarbonization. On the other hand, as an economic model to achieve sustainable growth, a circular economy with resource recycling is advocated, and as one of its measures, research is being conducted on biomassing of various product raw materials. As agricultural biomass, rice husks are produced in Japan at a rate of about 2 million tons per year. As an inorganic component, they contain a high concentration of 20% silica, so if they can be effectively used, they can contribute to both decarbonization and resource recycling.

[0008] The deodorant disclosed in Patent Document 1 discloses the use of porous carbon obtained by carbonizing organic waste derived from plants and animals as a material that exerts deodorizing ability. Although rice husks are exemplified as a raw material, it only discloses the use of carbon components obtained by carbonization as a material that exerts deodorizing ability.

[0009] An object of the present invention is to provide a deodorant containing silicon dioxide having a deodorizing function and a method for producing the deodorant by using biomass derived from silicic acid plants as a raw material.

[0010] Means of solving problems

[0011] In order to achieve the above object, the first characteristic structure of the deodorant of the present invention is that it is a deodorant using biomass derived from silicic acid plants as a raw material and is composed of a composite of 50-100wt% amorphous silica and 0-50wt% carbon.

[0012] Since amorphous silica adsorbs odorous gas components, it can exert good deodorizing ability. When carbon is contained, the deodorizing ability of carbon as a porous body can be exerted in a composite manner.

[0013] A second characteristic configuration of the present invention resides in that, in addition to the first characteristic configuration, the amorphous silicon dioxide has an acid site on its surface.

[0014] Since the surface of amorphous silica has an acid site, the deodorizing ability for alkaline odorous gas is increased. The surface having an acid site means, for example, a state in which a reactive group serving as an acid site is added to one bond of silica.

[0015] A third characteristic configuration of the present invention resides in that, in addition to the first characteristic configuration, the surface of the amorphous silicon dioxide has a basic site.

[0016] Since the surface of amorphous silica has a basic site, the deodorizing ability for acidic odorous gas is increased. The surface having a basic site means, for example, a state in which a reactive group serving as a basic site is added to one bond of silica.

[0017] The first characteristic feature of the method for producing a deodorant of the present invention is that it is a method for producing a deodorant using biomass derived from silicic acid plants as a raw material, and comprises a gasification step: by gasifying the above-mentioned biomass, a composite having an amorphous silicon dioxide content of 50 wt% or more and a carbon content of less than 50 wt% is obtained.

[0018] By gasifying the biomass, the organic components are removed, and the deodorizing ability is demonstrated through the composite of amorphous silica and residual carbon.

[0019] A second characteristic configuration of the present invention is that, in addition to the first characteristic configuration, a pulverization step is provided in which the composite material obtained in the gasification step is pulverized.

[0020] In the process of pulverizing the composite material in the pulverizing step, the exposed area of ​​amorphous silica increases, and the deodorizing ability is enhanced.

[0021] A third characteristic configuration of the present invention is that, in addition to the first or second characteristic configuration, an acid treatment step is provided in which the composite obtained in the gasification treatment step is brought into contact with an acid solution.

[0022] A fourth characteristic feature of the present invention is that, in addition to the first or second characteristic feature, an alkali treatment step is provided in which the composite obtained in the vaporization treatment step is brought into contact with an alkali solution.

[0023] Effects of the Invention

[0024] As described above, according to the present invention, a deodorant containing silicon dioxide having a deodorizing function and a method for producing the deodorant can be provided by using biomass derived from silicic acid plants as a raw material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an explanatory diagram showing an example of a deodorant production apparatus.

[0026] Figure 2 This is an explanatory diagram of a gasifier.

[0027] Figure 3 (a) is an illustration of the composition of rice husk used as a sample; Figure 3 (b) is an explanatory diagram of the conditions in the gasification treatment step.

[0028] Figure 4 (a) is a diagram illustrating the properties of synthesis gas generated by gasification; Figure 4 (b) is a diagram illustrating the composition of the composite obtained by the gasification treatment.

[0029] Figure 5 (a) is a diagram illustrating the relationship between water vapor ratio, vaporization rate, and specific surface area of ​​the composite; Figure 5 (b) Pore distribution diagram of the composite; Figure 5 (c) is a diagram illustrating the results of a gas phase adsorption test of odorous substances.

[0030] Figure 6 (a) is an explanatory diagram of the component analysis results of each composite; Figure 6 (b) is an explanatory diagram of the pore volume distribution of the composite.

[0031] Figure 7 (a) is an explanatory diagram of a characteristic curve showing the test results of the deodorizing effect of each composite on various odorous gas components; Figure 7 (b) is an explanatory diagram showing characteristic values ​​of the same test results.

[0032] Marking Description

[0033] 10: Gasifier

[0034] 20: Separation mechanism

[0035] 22: Heat exchanger

[0036] 24: Gas Cooling Tower

[0037] 26: Sawdust filter

[0038] 28: Induction fan

[0039] R1: lower area

[0040] R2: Upper region. DETAILED DESCRIPTION

[0041] Hereinafter, the deodorant of the present invention and an example method for producing the deodorant will be described.

[0042] The present invention is applicable to biomass agricultural wastes derived from silicic acid plants such as rice husks, rice straw, wheat straw, bamboo, corn, sugar cane, Miscanthus, and horsetail. For example, about 70% of rice husks are carbohydrates such as cellulose, hemicellulose, and lignin, about 15-20% are silicon dioxide, and most of the rest is water, with only a trace amount of alkaline impurities. The present invention is applicable to the case where such biomass containing silicon dioxide is recycled as a resource. The present invention is described below using rice husks as an example.

[0043] Figure 1 An example of a deodorant manufacturing device is shown in the figure, which is used to implement a method for manufacturing a deodorant using rice husk as a raw material.

[0044] The deodorant manufacturing device includes: a gasifier 10 for thermally decomposing and gasifying rice husk as biomass; a separation mechanism 20, such as a centrifugal cyclone filter, for separating the biomass residue from a mixture of the thermal decomposition gas and the biomass residue discharged from the gasifier 10; and a pulverizer 30 for pulverizing the biomass residue separated by the separation mechanism 20. The biomass residue separated by the separation mechanism 20 is a deodorant.

[0045] The thermal decomposition gas separated by the separation mechanism 20 is guided along the exhaust route by the exhaust fan 28, passes through the heat exchanger 22, and is cooled in the gas cooling tower 24. Furthermore, the exhaust gas is discharged into the atmosphere after tar is removed in the sawdust filter 26.

[0046] like Figure 2 As shown in FIG. 1 , the gasifier 10 is a vertical fluidized bed furnace of a two-stage cylindrical structure with a larger diameter at the upper portion than at the lower portion. The structure is as follows: the raw material rice husks and water vapor and air as gasifying agents are supplied from the bottom of the gasifier 10, and the rice husks are stirred at high speed in the furnace to be partially burned and gasified. As the reaction proceeds, the rice husks become smaller than a certain particle size and are discharged from the upper portion of the furnace together with the synthesis gas.

[0047] The rice husks stored in the rice husk hopper 11 are quantitatively fed into the gasifier 10 through the screw feeding conveyor 12. Figure 1 The boiler shown generates superheated steam and Figure 1 The air heated by the heat exchanger is supplied from the lowermost portion of the gasifier 10, and the rice husk is stirred at a high speed in the formed spouted bed.

[0048] The rice husks fed into the gasifier 10 undergo a water-gas reaction or a water-gas shift reaction at a high temperature of 550°C to 800°C under normal pressure and are gasified and discharged from the exhaust port at the top. The water-gas reaction mainly occurs in the lower region R1 of the gasifier 10, and the water-gas shift reaction mainly occurs in the upper region R2 rising in the gasifier 10.

[0049] The water gas reaction is an endothermic reaction in which solid carbon C as biomass and water vapor H2O generate carbon monoxide CO and hydrogen H2 in a high temperature environment of 500°C or higher, as shown in the following formula. In addition to the water vapor supply unit, an oxygen supply unit is provided to supply a small amount of oxygen or air to the gasifier 10, and the necessary reaction heat is provided by partial combustion of the biomass. In the present embodiment, the temperature is adjusted to 550 to 650°C.

[0050] C+H2O→CO+H2

[0051] The water gas shift reaction is an exothermic reaction that generates carbon dioxide CO2 and hydrogen H2 from carbon monoxide CO and water vapor H2O at a high temperature of about 800°C as shown in the following formula. In the present embodiment, the temperature is adjusted to 700-800°C to maintain the silicon dioxide in the rice husk in an amorphous state.

[0052] CO+H2O→CO2+H2

[0053] The synthesis gas generated from the biomass by the water-gas reaction in the lower region R1 and the ash containing carbides and silicon dioxide rise to the upper region R2 along the flow direction of the gas, thereby promoting the water-gas shift reaction. In addition, the water vapor required for the water-gas shift reaction is supplied by the water vapor supply unit, and the water vapor in the lower region R1 that does not participate in the water-gas reaction can be used.

[0054] The temperature of the rice husk during thermal decomposition in the gasifier 10 needs to be at least lower than the phase transition temperature region where silicon dioxide contained in the rice husk crystallizes, for example, needs to be below 800° C. This is because if silicon dioxide crystallizes, it is not suitable for industrial use from the perspective of health effects.

[0055] In addition, by adjusting the ratio of air (oxygen) supplied to the gasifier 10, it is possible to adjust whether the gasification reaction of the rice husk is mainly promoted or the combustion reaction of the rice husk is mainly promoted, and as a result, the composition of the biomass residue containing silicon dioxide (ash) or carbide (coke, char) separated in the separation mechanism can be adjusted. When the gasification reaction is promoted, in addition to the silicon dioxide component, a composite with a high carbon content can be obtained, and when the combustion reaction is promoted, a composite with a high silicon dioxide component and a very low carbon content can be obtained.

[0056] That is, by gasifying the biomass in the gasifier 10, a method for manufacturing a deodorant having a composite of 50 wt% or more amorphous silica and less than 50 wt% carbon can be achieved. In addition, by a pulverizing step of pulverizing the composite obtained by the gasification step using a pulverizer 30, the deodorizing ability can be enhanced. Generally, if the deodorant has carbon as the main component, the deodorizing ability tends to decrease by pulverizing, but as a deodorant containing a composite of silica, the deodorizing ability increases by pulverizing. It is considered that this is because, by pulverizing, the silica reveals a new face that exhibits adsorption performance.

[0057] As the deodorant obtained, since the carbon component exhibits hydrophobicity and the silica component exhibits hydrophilicity, when manufacturing a deodorant in a kneaded form with an aqueous composition, the more the composition of the silica component exhibiting hydrophilicity, the more uniform the kneaded product is distributed, and as a result, a deodorant with high deodorizing performance can be achieved. On the contrary, since it is difficult to uniformly distribute the carbon component exhibiting hydrophobicity and the kneaded product, when manufacturing such a deodorant, it is preferred to perform a gasification treatment step in an environment that promotes a combustion reaction.

[0058] In addition, by carrying out an acid treatment step of contacting the composite obtained in the gasification step and / or the composite crushed in the crushing step with an acid solution, a deodorant having an acid site on the surface of amorphous silica can be obtained, and the deodorizing ability of alkaline odorous substances can be improved. For example, by immersing the composite in hydrochloric acid, stirring it for a predetermined time with a stirrer, etc., and then drying it, a powder deodorant having an acid site on the surface of amorphous silica can be obtained.

[0059] Furthermore, by carrying out an alkali treatment step of bringing the composite obtained in the gasification step and / or the composite pulverized in the pulverization step into contact with an alkali solution, a deodorant having an alkaline site on the surface of amorphous silica can be obtained, and the deodorizing ability against acidic odorous substances can be improved. For example, by immersing the composite in a sodium hydroxide solution, stirring it for a predetermined time with a stirrer or the like, and then drying it, a powder deodorant having an alkaline site on the surface of amorphous silica can be obtained.

[0060] Acidic odor substances refer to acidic gases that cause bad odors, specifically, acetic acid, isovaleric acid, butyric acid, etc. In addition, alkaline odor substances refer to alkaline gases that cause bad odors, specifically, ammonia or organic amines that are produced in large quantities in sewage treatment plants, feces and urine treatment plants, garbage incinerators, etc.

[0061] Example

[0062] Rice husks were activated by gasification treatment using a test device simulating the above-mentioned deodorant production device, and a porous and amorphous deodorant was produced, and the adsorption performance for odorous gases was evaluated.

[0063] Figure 3 (a) shows the composition of the rice husk used as a sample. In order to determine the differences in properties between different regions, rice husks from 12 varieties in 8 prefectures and cities, including the rice husks used for the test, were analyzed. No significant differences were found due to different regions. The combustible components (organic components) were about 80%, and the ash (inorganic components) were about 20%. About half of the combustible components were carbon, and about 95% of the ash was silicon dioxide (SiO2). The remaining % was fertilizer components such as K, Ca, and P.

[0064] The deodorant was manufactured using a test device with a capacity of 1 t / day (based on the input of rice husk). The gasifier 10 is a two-stage cylindrical fluidized bed type as described above. The raw material rice husk and water vapor (evaporator steam) and air of the gasifier are supplied from the bottom of the furnace, and the rice husk is stirred at high speed in the furnace to be partially burned and gasified. As the reaction proceeds, the rice husk becomes smaller than a certain particle size and is discharged from the upper part of the furnace together with the synthesis gas. The silica-containing compound discharged from the gasifier 10 is collected in a cyclone filter.

[0065] Figure 3 (b) shows the operating conditions of the device. The temperature in the furnace was adjusted to 550 to 650°C in the lower region R1 and 700 to 800°C in the upper region R2.

[0066] The specific surface areas of the generated composites containing silica were compared and evaluated under the gasification promoting condition (RUN1) with the air ratio (O2 / C ratio) set to 0.3 and the water vapor ratio (H2O / C ratio) varied from 0.8 to 1.8 based on 1.5. In addition, the operation was carried out under the combustion promoting condition (RUN2) with the air ratio increased to 1.4, and the composite containing silica with a low carbon concentration was evaluated.

[0067] Figure 4 (a) shows the average properties of the synthesis gas. Under the gasification promotion condition (RUN1), the reducing components CO, H2, and CH4 are the main components, and under the combustion promotion condition (RUN2), the oxidizing components O2 and CO2 are the main components. Under the gasification promotion condition (RUN1), 0.26 kg of the composite containing silica and 1.45 Nm of synthesis gas were discharged by treating 1 kg of rice husk. 3 The conversion rate of C in rice husk to synthesis gas (hereinafter referred to as gasification rate) was calculated to be 62.7%. In addition, the calorific value of the synthesis gas was calculated to be 3,232 kJ / Nm 3 , the air conditioning efficiency is calculated to be 30%.

[0068] Figure 4(b) shows the properties of the composite containing silica. Under the gasification-promoting condition (RUN1), about 40% of the combustible components remain, and a composite material of silica and carbon is generated. In contrast, under the combustion-promoting condition (RUN2), almost no combustible components remain, and an ultra-high-purity silica material with a silica concentration of about 95% is generated. The specific surface area of ​​the composite under the gasification-promoting condition (RUN1) is as high as 224 m 2 / g. It is believed that this is because the carbon in the rice husk is activated by water vapor and becomes porous during the gasification process. By adjusting the gasification promotion conditions (RUN1) and the combustion promotion conditions (RUN2), a deodorant composed of a composite of 50-100wt% amorphous silica and 0-50wt% carbon can be obtained. When other inorganic components are added, a deodorant composed of a composite of 50-95wt% amorphous silica and 0-45wt% carbon can be obtained.

[0069] Figure 5 (a) is shown in Figure 4 (b) The relationship between the water vapor ratio, the gasification rate, and the specific surface area of ​​the composite when the water vapor ratio is changed under the gasification promotion condition (RUN1). It can be seen that the higher the water vapor ratio, the higher the specific surface area of ​​the composite. It can be considered that the higher the water vapor ratio, the higher the empty tower velocity in the furnace, the shorter the residence time, and the relatively lower the gasification rate, so more porous carbon remains and the specific surface area increases.

[0070] Figure 5 (b) shows the Figure 4 (b) The results of pore distribution measurement of the composite obtained under the gasification promotion condition (RUN1). Most of the pores are micropores less than 1 nm. In addition, when the crystal identification is performed based on XRD analysis, the silica is amorphous regardless of the conditions. It can be considered that because the gasification furnace is a fluidized bed type, the rice husk is always stirred in the furnace, there is no local high temperature part, and the reaction time is as short as about tens of seconds, so crystallization does not occur even at high temperatures.

[0071] The composites (crushed products) produced under the gasification-promoting conditions (RUN1) and the combustion-promoting conditions (RUN2) were subjected to a gas-phase adsorption test for 10 odorous substances to evaluate the adsorption characteristics.

[0072] Cut open a corner of the 10L air bag, insert a petri dish loaded with 10mg of the complex to block it, inject a specified concentration (set by the odor threshold) of the odor substance to be adsorbed with a syringe, and let it stand at room temperature for 1 hour. Then, collect a portion of the gas in the bag, quantify the concentration of the odor substance using a detection tube or GC-MS, and calculate the adsorption removal rate from the concentration reduction rate relative to the blank condition.

[0073] Figure 5 (c) shows the test results. The composite material under vaporization-promoting conditions exhibits a high adsorption removal rate for a wide range of odorous substances such as fatty acids, aldehydes and ketones, aromatics, and sulfur series. The composite material under combustion-promoting conditions also exhibits adsorption capacity for some substances. In the composite material under vaporization-promoting conditions, polar (hydrophilic) silica and non-polar (hydrophobic) carbon are compounded, and adsorption can be performed based on various mechanisms such as chemical adsorption via polar functional groups and physical adsorption of non-polar parts. Therefore, it is believed that the range of adsorbable substances is wider than that of the composite material under combustion-promoting conditions. In addition, most pores with a pore size of less than 1 nm are roughly the same as the molecular size of odorous substances, which is also believed to be the reason for the high adsorption rate.

[0074] Furthermore, by subjecting the composite of silicon dioxide and carbon under the gasification-promoting conditions, that is, high-carbon gasification ash, to acid treatment / alkali treatment, it was confirmed whether the adsorption performance changed.

[0075]

Table 1

[0076]

[0077] Table 1 shows the Figure 4 The adsorption characteristics of acetic acid, acetaldehyde and pyridine were tested for the composite obtained under the gasification promotion conditions of (b), the untreated composite (untreated composite), the composite obtained after the acid treatment step of contacting with an acid solution (hydrochloric acid) and drying (acid-washed composite), and the composite obtained after the alkali treatment step of contacting with an alkali solution (sodium hydroxide) and drying (alkali-washed composite). Acetic acid as an acid substance showed good results for alkali-treated alkali-washed ash, acetaldehyde for alkali-treated alkali-washed ash, and pyridine as an alkaline substance for acid-treated acid-washed ash.

[0078] In order to study the relationship between the adsorption results and the adsorption points of each composite, the results of TPD test are shown in Table 2.

[0079]

Table 2

[0080]

[0081] ※nd not tested

[0082] According to the above content, it can be evaluated as follows for acidic substances (acetic acid etc.): the result sequence of CO2-TPD is associated, and acidic substances are mainly adsorbed on the base site. In addition, it can be evaluated as follows for nonionic polar substances (aldehyde etc.): the result sequence of NH3-TPD without water vapor treatment is associated, and polar substances are mainly adsorbed on the acid site, particularly weak acid site. Further, it can be evaluated as follows for alkaline substances (pyridine etc.): the result sequence of NH3-TPD with water vapor treatment is associated, and alkaline substances are mainly adsorbed on the strong acid site.

[0083] like Figure 6 As shown in (a), the following complexes are prepared respectively: Figure 4 (b) under the gasification promotion conditions (RUN1) obtained by the composite A; the composite B of the composite A pulverized by grinding; the composite C of the alkali treatment of the composite A; Figure 4 The composite obtained under the combustion promoting condition (RUN2) of (b) is pulverized by a grinder and is a pulverized composite D.

[0084] Figure 6 (b) shows the pore distribution of composite A (original ash) and alkali-treated product C of composite A. It was confirmed that both the micropore distribution and the mesopore distribution increased by alkali washing.

[0085] Figure 7 (a) and (b) show the blank conditions and the results of the confirmation test of the deodorizing effect of composites A, B, C, and D of rice husk biochar on the odorous gas components of hydrogen sulfide, sulfur, ammonia, amines, organic acids, aldehydes, esters, aromatics, and hydrocarbons generated by foods (horse mackerel, kimchi, pickled radish, and fried dumplings).

[0086] Fill a 5L air bag with 10g of each of the above-mentioned compounds A, B, C, and D (sample) and food (source of odor), seal it and place it in a refrigerator (3°C constant temperature bath) to stand, and sample and analyze the internal gas after 1 day and 3 days to produce the results. There was basically no difference in the blank condition, but a certain deodorizing effect was confirmed in 10g of each of the compounds A, B, C, and D (sample). The odor intensity was in the following order: blank>complex D>complex A>complex B>complex C.

[0087] From the above content, it can be seen that the deodorant containing amorphous silica obtained by gasifying biomass derived from silicic acid plants as raw materials, especially the deodorant containing amorphous silica as the main component produced under gasification-promoting conditions, has the ability to adsorb a wide range of odorous substances and has material characteristics as a deodorant.

[0088] The above embodiment is a specific example of the deodorant and the method for producing the deodorant according to the present invention. The scope of the present invention is not limited to this description, and the specific composition of the composite can be appropriately set while satisfying the above numerical range.

Claims

1. A deodorant, characterized in that: The raw material is biomass derived from silicic acid plants and is composed of a composite material in which amorphous silicon dioxide accounts for 50 to 100 wt % and carbon accounts for 0 to 50 wt %.

2. The deodorant according to claim 1, characterized in that The surface of the amorphous silicon dioxide has acid sites.

3. The deodorant according to claim 1, characterized in that The surface of the amorphous silicon dioxide has a basic site.

4. A method for producing a deodorant, characterized in that: This is a method for producing a deodorant using biomass derived from silicic acid plants as a raw material. The production method comprises a gasification step: the biomass is gasified to obtain a composite having 50 wt% or more of amorphous silicon dioxide and less than 50 wt% of carbon.

5. The method for producing a deodorant according to claim 4, characterized in that: A pulverization step is provided: the composite material obtained in the gasification step is pulverized.

6. The method for producing a deodorant according to claim 4 or 5, characterized in that: An acid treatment step is provided: the composite obtained in the gasification treatment step is brought into contact with an acid solution.

7. The method for producing a deodorant according to claim 4 or 5, characterized in that: An alkali treatment step is provided: the composite obtained in the gasification treatment step is brought into contact with an alkali solution.

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