KR102011717B1 - Method for producing biodiesel using rice bran - Google Patents

Abstract

The present invention provides a method for producing biodiesel using rice bran obtained as a by-product from rice milling process. The present invention proposes a method for producing biodiesel by adding alcohol to rice bran containing fats and oils and lipases on its own, and optimal conditions for synthesizing biodiesel for increasing the production yield of biodiesel. In addition, a method of producing biodiesel by adding fat and alcohol to degreasing rice bran is presented. The present invention enables the production of biodiesel in a very simple way by utilizing skim milk or rice bran, which is discarded after obtaining rice bran or rice bran oil obtained as a by-product during rice milling, thereby simplifying the production method of biodiesel. It can contribute to the spread of biodiesel by reducing the production cost and reducing the production cost.

Description

Method for producing biodiesel using rice bran {Method for producing biodiesel using rice bran}

The present invention relates to a method for producing biodiesel using rice bran obtained as a by-product from rice milling process.

Currently, the importance of developing biodiesel, an alternative fuel, is increasing due to the reduction of oil reserves worldwide and the reduction of greenhouse gas emissions generated when using fossil fuels. Biodiesel is a non-toxic, biodegradable and renewable fuel energy, especially with low greenhouse gas emissions such as carbon monoxide, carbon dioxide and sulfuric acid gas.

Biodiesel is a mono alkyl ester of long chain fatty acids and short chain alcohols contained in vegetable oils or animal fats. In general, biodiesel synthesis reactions use chemical catalysts or enzyme catalysts, and chemical catalytic reactions use sodium hydroxide, potassium hydroxide, or sulfuric acid. That's how it is. However, a large amount of wastewater treatment costs generated in the neutralization reaction and salt removal process to be carried out after the reaction is expensive and it is difficult to recover glycerol. On the other hand, when using an enzyme catalyst, there is a disadvantage that the enzyme is expensive, it is easy to separate the catalyst and the reaction product, there is no need for an additional treatment process, there is an advantage that the recovery of the reaction by-product glycerol is easy. In addition, since the enzymatic reaction occurs under relatively mild conditions, there is little additional energy use, and the biodiesel yield can be increased by preventing soap formation.

On the other hand, rice is the world's three largest crops along with wheat and corn, and rice bran removed from the milling process is about 10% of the brown rice weight. Rice bran contains vegetable sterols, tocopherols, tocotrienols, gamma-oryzanol, and ungumified products, and rice bran is utilized for the extraction of these useful components or rice bran oil. In addition, degreasing rice bran can be used as an animal feed, but most of them have been disposed of. Rice bran has a high hydrolytic activity of lipase, so that rice bran oil is easily hydrolyzed in the rice milling process, and thus the acid value of rice bran oil is higher than other plant fats and oils. For this reason, many methods have been studied to inhibit the activity of lipase contained in rice bran causing hydrolysis. However, to date, no attempt has been made to efficiently use lipases contained in rice bran.

The present invention is to provide a method for producing biodiesel using rice bran, which is a by-product produced in the milling process.

The production of biodiesel using enzymes requires the use of fats and oils, and lipases that react with them. However, lipases have to be purchased or synthesized and used to fix them to a carrier, and then use a complex process such as separation and recovery after use, thereby increasing the production cost of biodiesel.

The present inventors have been interested in using the rice bran lipase contained in rice bran obtained as a by-product during the rice milling process while studying the synthesis of lipase and biodiesel using the same. However, the present inventors, surprisingly, without the process of separating the rice bran lipase from the rice bran, when using the oil and rice lipase contained in the rice bran itself to add biodiesel by simply adding alcohol to induce biodiesel synthesis reaction It can be produced in high yield.

Hereinafter, the present invention will be described in more detail.

The present invention

The present invention provides a method for producing biodiesel using rice bran, which comprises dispersing alcohol in rice bran, allowing the rice bran to stand in a reactor to synthesize biodiesel, and separating starburst biodiesel.

The method of producing biodiesel according to the invention is surprisingly simple. As can be seen in the examples below, the present invention shows that biodiesel is produced by simply dispersing alcohol in rice bran and allowing it to stand in the reactor. That is, the present invention simplifies the step of supplying fats and oils and the addition of lipases, which are essential in the production method of biodiesel using general enzymes, by using fats and oils and lipases contained in rice bran itself. Enzymatic immobilization and separation steps, which are pointed out as a problem of enzymatic reaction system by using lipase in rice bran without separation, are not necessary. This method is distinguished from existing chemical or enzymatic reaction systems, and does not require a separate complicated process, thereby enabling biodiesel to be economically synthesized.

In the present invention, the fact that the rice bran, in which the alcohol is dispersed, is allowed to stand in the reactor means that the biodiesel synthesis reaction, that is, the production of fatty acid alkyl ester proceeds. The biodiesel synthesis reaction according to the present invention does not require a separate stirring process used in the conventional biodiesel synthesis process. Therefore, the reactor used in the present invention is sufficient to provide a space for reaction in which biodiesel can be synthesized, and only the basic configuration of the inlet portion of the substrate and the outlet portion of the biodiesel is provided, and no special device is provided. You don't have to. However, it may be desirable to have a dispersion device or agitation device for evenly dispersing the alcohol in the rice bran, but a separate stirring is not essential during the biodiesel synthesis reaction after the alcohol dispersion.

The method for producing biodiesel using rice bran according to the present invention includes a process of separating the synthesized biodiesel. In the process of the invention, the synthesis of biodiesel means the production of fatty acid alkyl esters. When oil in rice bran is used as a reaction substrate, biodiesel, ie fatty acid alkyl esters, will accumulate in rice bran. Therefore, the biodiesel can be finally obtained by extracting the fatty acid alkyl ester from, for example, a conventional organic solvent from the rice bran after the synthesis of the fatty acid alkyl ester is completed. In the case of using degreasing rice bran, since additional fats and oils are added as a reaction substrate, in this case, biodiesel is contained in a reaction product including degreasing rice bran and / or added fats and oils, and biodiesel is extracted and / or Alternatively, the biodiesel can be finally obtained by purification. The rice bran obtained after biodiesel separation can be reused in a two-step synthesis process or in a separate biodiesel production plant. As the organic solvent that can be used for the extraction, a conventional organic solvent used for the extraction of fats and oils can be used. For example, hexane, tert-butanol, isopropyl alcohol, isooctane, chloroform, diethyl ether, petroleum ether, etc. Can be used. The composition and amount of oil to be extracted may vary depending on the polarity of the solvent. The solvent having a higher polarity increases the extraction of the polar lipid component. Increasing unnecessary polar lipid components in biodiesel extraction can be a factor in reducing biodiesel purity. In view of this, the most preferred solvent for extraction of biodiesel may be, for example, hexane.

Biodiesel production method using the rice bran according to the present invention can be carried out by recycling the rice bran obtained after the separation of the biodiesel. Intravitreal oils will be exhausted during the first stage synthesis of biodiesel, but bran lipases are present in the rice bran with the enzyme activity maintained continuously. As can be seen in the following examples, the rice bran used in the synthesis of biodiesel can effectively perform the role of lipase even after repeated use up to about 10 times.

Thus, in one embodiment of the invention,

The production method,

After adding the fat or oil to the rice bran obtained after the biodiesel separation and dispersing the alcohol, it is left in the reactor to synthesize biodiesel, and further comprising the step of separating the synthesized biodiesel, the process is one to Can be repeated 10 times.

In view of the repeated use of rice bran lipase, it may be considered to use degreasing rice bran which is obtained and discarded rice bran oil as a rice bran for the synthesis of biodiesel according to the present invention.

 Therefore, the inventors of the present invention devised a method of using lipase in degreasing rice bran, but adding the fats and oils lacked in degreasing rice bran.

In one embodiment of the invention, when the rice bran is degreasing rice bran, the production method according to the invention

After adding fats and oils to skim rice bran and dispersing alcohol, these mixtures were left to synthesize biodiesel,

Isolating the synthesized biodiesel.

Degreased rice bran can also function as a lipase even after repeated use. Therefore, in one embodiment of the method for producing biodiesel according to the present invention, after the synthesis and separation of biodiesel using degreasing rice bran, fats and oils are added to the degreasing rice bran, the alcohol is dispersed, and the biodiesel is allowed to stand in a reactor. It further comprises the step of synthesizing, separating the synthesized biodiesel, the process can be repeated 1 to 10 times.

In another embodiment of the present invention, the rice bran may have an acid value of 0 to 200, such as 0 to 100. Rice bran is rapidly increased in acidity with time in the rice milling process, so if the rice bran is supplied with low price, the acid value may be high. As the acid value increases, the production yield of biodiesel is somewhat lowered, but as can be seen in the following examples, there is no particular problem to implement the production of biodiesel from rice bran according to the present invention. Therefore, the acid value of rice bran used in the present invention is not particularly limited.

The type of fat or oil additionally added to the rice bran or degreasing rice bran which is reused through the primary synthesis of biodiesel is not particularly limited, and generally, any known oil that can be used for the production of biodiesel can be used. For example, the oil or fat may be vegetable oil, animal oil, algae oil, oil-derived microorganism oil, oil distilllate fatty acid, waste oil or acid oil, and the like. . Examples of vegetable fats and oils include, but are not limited to, soybean oil, palm oil, coconut oil, rapeseed oil, canola oil, sunflower oil, rice bran oil, and the like. Examples of animal fats and oils are derived from fish, algae, mammals, and the like. It may be one oil. Algae that can be used for oil supply include marine microalgae, flax algae, and freshwater microalgae. Specific examples include Nannochloropsissp . , Isochrysis sp . And Scenedesmussp. .), and chlorella (including the Chlorellasp.) and the like. In addition, oil- producing microorganisms include, for example, Aeromonas microorganism, Achromobacter microorganism, Acidovorax delafieldii , Acidovax facilis , Acinetobacter genus microorganism, Actinomyces genus microorganism, Aeromonas Genus Microorganism, Alcaligenes genus Microorganism, Alteromonas Genus Microorganism, Althornia genus microorganism, Aplanochytrium genus microorganism, Aspergillus genus microorganism, Amoebobacter genus microorganism, Aphanocapa sp., Aphanothece sp. Aquaspirillum autotrophicum , Azorhizobium caulinodans, Azospirillum sp., Azospirillum spp, Azotobacter spp, Bacillus spp, Beggiatoa spp, Beijerinckia spp, Beneckea spp, Blakeslea spp, Bordetella pertussis , Bradyrhizobium japonicum , Caryophamon latum , Caulobacter genus microorganism, Chlorogloea genus microorganism, Chromatium Genus Microorganism, Chromobacterium Genus Microorganism, Clostridium Genus Microorganism, Comamonas Genus Microorganism, Corynebacterium Genus Microorganism, Crypthecodinium Genus Microorganism, Cyanobacteria Genus Microorganism, Derxia Genus Microorganism, Desulfonema Genus Microorganism, Desulfosacina variabilis , Desulfovibrio sapovorans , Ectothiorhodospira genus microorganism, Elina genus microorganism, Entomophthora Microorganism , Ferrobacillus ferroxidans , Flavobacterium sp., Haemophilus influenzae , Halobacterium genus microorganism, Haloferax mediterranei , Hydroclathratus clathratus, Hydrogenomonas facilis, Hydrogenophaga spp, Hyphomicrobium spp, Ilyobacter delafieldii , Japonochytrium Genus microbiology, Labrys monachus , Lamprocystis reseopersicina , Lampropedia hyalina , Legionella sp., Leptothrix discophorus, Methylobacterium spp, Methylosinus spp, Micrococcus spp, Mortierella spp, Mycobacterium spp, Nitrobacter spp, Nocardia spp, Paracoccus dentrificans , Oscillatoria limosa, Penicillium cyclopium, Photobacterium spp, Physarum ploycephalum , Phycomyces genus, Pseudomonas genus, Pythium genus, Ralstonia genus, Rhizobium genus, Rhodobacillus genus, Rhodobacter genus, Rhodococcus Genus microorganism, Rhodocyclus genus microorganism, Rhodomicrobium vannielii, Rhodopseudomonas spp, Rhodospirillum spp, Schizochytrium microorganism of the genus Sphingomonas paucimobilis , Spirillum genus microorganism, Spirulina genus microorganism, Staphylococcus genus microorganism, Stella genus microorganism, Streptomyces genus microorganism, Syntrophomonas wolfei , Thermophilic cyanobacteria , Thermus thermophilus , Thiobacillus A2, Thiobacillus Genus microorganism, Thiocapsa Genus microorganism, Thraustochytrium genus microorganism, Thiocystis violacea , Vibrio parahaemolyticus , Xanthobacter autotrophicus , Xanthomonas maltophilia , Zoogloea genus microorganisms and transformed with genes encoding the enzyme having the ability to produce oil, and the like, but is not limited thereto. Distilled fatty acids can come from all oils, so oil diseillate fatty acids are by-products that occur in the purification of oils and fats and can be derived from oils of all origin, for example palm oil fatty acids. On the other hand, acid oil (Acid oil) refers to the oil extracted by acid treatment (Acidification) extracted from the by-product of the soap (Soapstock) generated during the deoxidation process during the oil refining process. Examples of such acid oils include acid oils derived from rice bran which can be obtained during the purification of rice bran oil.

Although not limited thereto, the fats and oils are preferably added at a ratio of 5 to 25% of the total weight of fat and rice bran when considering biodiesel yield.

In the biodiesel production method of the present invention, the synthesis of biodiesel is produced according to various conditions such as the state of rice bran used (degreasing, acid value, etc.), the type of alcohol, reaction temperature, fat and oil: molar ratio of alcohol, and the like. can be changed. When the synthesis of biodiesel is carried out under specific conditions, the production yield of biodiesel is improved, but the production yield is that the user can select any cutoff value in order to obtain economic feasibility. It should not be construed as limiting Whatever conditions are selected, the biodiesel production method of the present invention can produce biodiesel by the simple process described above.

In the present invention, alcohol dispersed in rice bran for the production of biodiesel may be used as long as it can be used for production of biodiesel. Preferably, short-chain alcohols, that is, C1-6 lower alcohols, in particular C1-4 alcohols such as methanol, ethanol, isopropyl, butanol and the like can be used as the alcohol dispersed in the rice bran. For example, when methanol is used as alcohol, methanol separates glycerol from triglycerides and breaks it down into free fatty acids, and lipase in rice bran causes esterification of these free fatty acids, producing fatty acid methyl esters as biodiesel. Likewise, when ethanol is used as the alcohol, fatty acid ethyl esters are produced as biodiesel.

In one embodiment of the invention, the alcohol dispersed in the rice bran may be methanol. It is generally considered that alcohols used for the synthesis of biodiesel have long chains, but the following examples show that methanol is the most suitable alcohol for reaction with fats and oils.

The amount of alcohol required for biodiesel synthesis correlates with the amount of lipase or oil. Therefore, in the present invention, the amount of alcohol dispersed in the rice bran should be appropriately adjusted according to the amount of fat or oil added to the recycled rice bran or degreasing rice bran in consideration of the amount of lipase present in the rice bran. .

If you use regular rice bran, the amount of lipase and fat or oil in the rice bran is fixed. On the contrary, in the case of using recycled rice bran or degreasing rice bran, the amount of lipase in rice bran may be fixed but the amount of fat or oil may vary. Therefore, it is necessary to appropriately adjust the amount of fat and alcohol to be added. For example, increasing the amount of fats and oils added to rice bran may increase the absolute amount of biodiesel synthesized, but the time required for synthesis may increase, and therefore, an appropriate amount and ratio should be selected in consideration of cost and time.

In the present invention, the alcohol inhibits the hydrolysis of the rice bran and is involved in the ester reaction in the synthesis of biodiesel. Considering the appropriate amount of alcohol that does not inhibit the activity of rice bran lipase, it is preferable that the alcohol is dispersed in 0.1 to 100 parts by weight based on 100 parts by weight of rice bran.

In the following examples, when adding 10%, 15%, 20%, 25% fat or oil based on the sum of the weight of rice bran and fats and fats added thereto, the synthetic yield of biodiesel depends on the molar ratio of fats and oils: alcohol. Show the results of analyzing how the changes are made.

The amount of fats and oils: fats and fats: fats and fats: 10% to 25% of the total weight of the rice bran and fats and oils to obtain an optimum yield by adjusting the molar ratio of alcohols between 1: 1 and 1: 3. The molar ratio of can be determined.

In another embodiment of the present invention, the synthesis of biodiesel may be carried out under the condition that the molar ratio of fats and oils: 1: 1 to 1: 3. It was shown that the molar ratio of fats and oils to the above ranges is sufficient to obtain sufficient reaction between substrates and high reaction yields. Unless otherwise indicated, the molar ratio of fats and oils according to the present specification is based on fatty acids in fats and oils. That is, in this specification, the molar ratio of fats and oils: alcohol means a molar ratio of fatty acid: alcohol. In a preferred embodiment, the molar ratio of fats and oils: alcohol can be from 1: 1.5 to 1: 2.5.

In another embodiment of the invention, the synthesis of biodiesel can be made at 20 to 70 ℃, for example, 20 to 50 ℃, 30 to 60 ℃ and the like. In the following examples, the temperature range in which the production yield of biodiesel can be increased is 20 to 70 ° C, among which the optimum yield is shown at about 40 ° C. Within the above temperature range, both constant temperature and ambient temperature conditions will be acceptable. In consideration of the convenience in the case of actual industrialization, the temperature may be 20 to 50 ° C.

In another embodiment of the present invention, the rice bran used in the synthesis of biodiesel may have a water content of 5-25%. Preferably the rice bran may have a water content of 10 to 15%. Moisture in rice bran is associated with acid value, and the higher the moisture, the higher the acid value. In the method of the present invention, biodiesel can be produced even when using a high acid value rice bran, but in order to increase the production yield, it may be preferable to use rice bran having an appropriate acid value because the water content is within the above range.

Biodiesel production method from rice bran according to the present invention can be maximized through a two-step synthesis process. In order to improve the yield of biodiesel, it is characterized by supplying additional substrates to the reactants and maximizing the reaction yield. For example, the biodiesel production method of the present invention extracts biodiesel from the reactants obtained after the synthesis of biodiesel, removes water and alcohol from the residue, and then disperses the alcohol again, and stands in the reactor to synthesize biodiesel. It may further include. This process can lead to production yields of biodiesel from rice bran up to 96% by weight.

In the method for producing biodiesel from rice bran according to the invention, the synthesis of biodiesel can also be carried out in a solvent. The solvent used in such a solvent-based synthesis method does not participate in the reaction, and may be used as a medium, and a solvent used in a conventional solvent-based synthesis method may be used, but is not limited thereto. For example, hexane, Tertiary butanol, isopropyl alcohol, isooctane, chloroform, diethyl ether, petroleum ether and the like can be used. When the synthesis of the biodiesel according to the present invention is carried out in a solvent, it may be preferable in that the biodiesel can be extracted simultaneously with the synthesis of the biodiesel in the solvent system, thereby simplifying the production process.

In one embodiment of the present invention, the biodiesel synthesis process may be performed for about 7 days to about 21 days. The time required for the synthesis is also related to the yield and can be arbitrarily adjusted by the user. Within the range of about 9 days to about 15 days, high production yields can be obtained, which may be more desirable.

The present invention proposes a method for producing biodiesel by adding alcohol to rice bran which itself contains fats and enzymes, and optimum conditions in the synthesis of biodiesel for increasing the production yield of biodiesel. The present invention enables the production of biodiesel in a very simple way by utilizing skim milk or rice bran, which is discarded after obtaining rice bran or rice bran oil obtained as a by-product in the rice milling process, thereby simplifying the production method of biodiesel. It can contribute to the spread of biodiesel by reducing the production cost and reducing the production cost.

1 is a graph showing a phenomenon that the hydrolysis of the rice bran is inhibited with the heat treatment time.
Figure 2 is a graph showing the synthesis yield of biodiesel using rice bran over the heat treatment time.
Figure 3 shows the synthesis yield of biodiesel according to the type of alcohol in biodiesel synthesis using rice bran.
Figure 4 shows the effect of the reaction temperature on the yield of biodiesel during biodiesel synthesis reaction using rice bran.
Figure 5 shows the effect of the molar ratio between the substrate on the biodiesel yield during biodiesel synthesis reaction using rice bran.
Figure 6 shows the effect of the moisture content in the rice bran in biodiesel synthesis reaction using rice bran.
7 is a graph showing that the two-step synthesis using moisture control can improve the synthesis yield of biodiesel using rice bran.
8 is a graph showing that the synthesis of biodiesel using rice bran according to the present invention is performed even when the high acid rice bran is used.
9 is a graph showing the effect of the type of solvent used for degreasing on biodiesel synthesis using degreasing rice bran.
Figure 10 shows the synthesis yield of biodiesel according to the type of fats and oils added during biodiesel synthesis using degreasing rice bran.
Figure 11 shows the effect of the content of soybean oil added to degreasing rice bran and the molar ratio of methanol according to the biodiesel synthesis.
Figure 12 shows the effect of the molar ratio between the substrate on the biodiesel yield at 15% fat content during biodiesel synthesis using skim rice bran.
Figure 13 shows the effect of the reaction temperature on biodiesel synthesis during biodiesel synthesis using degreasing rice bran.
Figure 14 shows the effect of the moisture content in the rice bran during biodiesel synthesis using degreasing rice bran to biodiesel synthesis.
FIG. 15 is a graph showing biodiesel yield according to the number of reactions under optimal conditions for biodiesel synthesis using degreasing rice bran. The treatment group is a case in which glycerol is generated during the reaction, and the control group is no glycerol removal.
FIG. 16 is a graph showing biodiesel synthesis yield using rice bran as a catalyst in a solvent system.

material

The rice bran used in this study was made from rice bran obtained from the process of refining domestic rice (Break-chan, Japonica rice). Rice bran was used to remove rice husks, embryos, wraps and other impurities using a 30 mesh sieve. At this time, the average water content and oil content of rice bran were 12% and 15%, respectively. Fats and oils used in biodiesel synthesis using skim rice bran are vegetable oils (soybean oil, canola oil), animal fats (lard), palm oil, palm oil fatty acid (deodorant distillate), waste cooking oil (M hamburger fries waste oil), acid oil (Acid oil) and the like. Prepared rice bran and degreasing rice bran was stored in -85 ℃ ultra low temperature freezer used. Tricaprin, an internal standard, was purchased from Sigma Aldrich (Seoul, Korea). Other reagents not mentioned were used above express.

Extraction and Analysis Method

The extraction process of the oil and fat component in rice bran using hexane is as follows. 4 g of substrate and 60 mL of hexane were added to a 250mL beaker and stirred at 300 rpm for 1 hour. And the hexane layer was separated by filtration. The above procedure was repeated four times and extraction was performed. The hexane layer containing the fats and oils was transferred to a 250 mL round flask and 60 Removal was carried out via a rotary vacuum evaporator at < RTI ID = 0.0 > C < / RTI >

About 40 mg of the extracted oil component was accurately weighed into a 5 mL volumetric flask and quantitatively analyzed by gas chromatography (Model 3800; Varian, Palo Alto, CA, USA) with an internal standard of 0.5 mg tricaprine. The column used a DB-1ht column (15 m × 0.25 mm i.d .; J & W Scientific, Folsom, Calif., USA) and the detector used a flame ionization detector. The temperature of the column was programmed to hold at 120 ° C. for 3 minutes, rise to 370 ° C. at 25 ° C./min, and then hold at 370 ° C. for 5 minutes. The carrier gas was flowed at 1.5 mL / min using helium. Both the inlet and the detector were kept at 370 ° C.

The acid value of the extracted oil component was measured by the AOCS Cd 3d-63 method.

The yield of synthesized biodiesel represents the percentage (by weight) of fatty acid alkyl esters in the extracted fats and oils.

Example  One: Rice bran  Biodiesel Synthesis

Using the fresh rice bran immediately after the scouring mill (initial acid value = 0), the reaction temperature, molar ratio, and water content in the rice bran were selected as parameters, and the biodiesel yield according to the reaction time was investigated to determine the optimum reaction conditions for each parameter. Investigate.

The biodiesel synthesis reaction process using rice bran used in this example is as follows. First, 100 g of rice bran and alcohol at a specific molar ratio based on fats and oils (fatty acids) contained in rice bran were added to a 1 L polypropylene bottle. Then, it was shaken vigorously for 5 minutes to distribute the alcohol evenly in the rice bran. Bioglycine was synthesized by transferring 4 g of rice bran evenly dispersed in alcohol into a 15 mL polypropylene bottle and sealing the alcohol to prevent it from flying.

Experimental Example  One: Rice bran  Confirmation of Biodiesel Synthesis by Internal Autozyme

Hydrolysis reaction and biodiesel yield through heat treatment using an autoclave used for microbial sterilization to determine whether the synthesis of biodiesel using rice bran according to Example 1 is a reaction by autologous enzyme, ie rice lipase, in rice bran. Was investigated. In order to confirm the degree of inhibition of enzyme activity, rice bran was sealed in a heat-resistant glass bottle (Media bottle) and heat-treated at different times of heat treatment for 0 minutes, 15 minutes, 30 minutes, and 60 minutes in an autoclave (121 ° C). In addition, in order to confirm the inhibitory effect of the hydrolytic activity of rice bran enzyme (rice lipase) according to the heat treatment time, 4 g of rice bran, which had been heat-treated for different periods of time, was sealed in a 15mL polypropylene bottle and reacted in a thermostat. In addition, to confirm the esterification activity of rice bran lipase according to the heat treatment time, that is, to inhibit the biodiesel synthesis reaction, a certain amount of methanol was added to the rice bran, which was heat-treated for different times, to perform a biodiesel synthesis reaction, that is, an ester reaction. The reaction process is as follows. First, 2 mol of methanol was added to the polypropylene bottle based on the amount of fat (fatty acid) contained in rice bran and rice bran. After that, the lid was sealed and then mixed vigorously for 5 minutes to allow methanol to be evenly dispersed in the rice bran. 4 g of the substrate evenly dispersed with methanol was transferred to a 15 mL polypropylene bottle and sealed by closing the lid to prevent methanol from flying away. Samples made through the above process were reacted in a thermostat maintained at a constant temperature to synthesize biodiesel. At this time, the reaction temperature was 40 ° C., and the moisture content in the rice bran was 12%.

(1) Change of Hydrolysis and Ester Reaction Activity of Enzyme with Heat Treatment Time

The rice bran was heat-treated in autoclave for 15 minutes, 30 minutes, and 60 minutes, and the activity of both the hydrolysis and ester reaction of the enzyme in the rice bran was inhibited.

(2) according to the heat treatment time Rice bran  Hydrolysis inhibition

1 is a graph showing a phenomenon that the hydrolysis of the rice bran is inhibited with the heat treatment time. In the case of the hydrolysis reaction, the rice bran, which had not been subjected to the high-pressure heat treatment, was stored at 40 ° C. for 15 days, and then the acid value of the oil (control) extracted with hexane was 110. In the case of, the acid values of the fats and oils extracted through hexane after storage under the same conditions were 28, 30, and 9, respectively.

(3) according to the heat treatment time Rice bran  Biodiesel Yield

Figure 2 is a graph showing the synthesis yield of biodiesel using rice bran over the heat treatment time. In the case of the ester reaction involved in biodiesel synthesis, the reaction was performed using raw rice bran which was not heat-treated through a sterilizer (Autoclave) to obtain biodiesel yield of 83% by weight on the 12th day. On the other hand, when the heat treatment for 15 minutes, 30 minutes, 60 minutes, yields of 34, 35, 12% by weight were obtained. Therefore, if the heat treatment for 15 or 30 minutes, the activity of the enzyme involved in biodiesel synthesis in the rice bran was inhibited to a similar level, and if the heat treatment for 60 minutes, it was more inhibited of the activity of the enzyme in the rice bran Could know.

From the results of Experimental Example 1, it was proved that biodiesel synthesized using rice bran was synthesized by rice bran lipase, which is an enzyme of rice bran.

Example  1- (1) Rice bran  Effect of Alcohols on Biodiesel Synthesis

Biodiesel was synthesized using methanol, ethanol, butanol (1-butanol) to confirm the effect of alcohol type on biodiesel synthesis using rice bran. Reaction conditions are oil-fat (fatty acid): alcohol molar ratio 1: 2, reaction temperature 40 It was ℃.

Figure 3 shows the synthesis yield of biodiesel according to the type of alcohol in biodiesel synthesis using rice bran. As shown in FIG. 3, on the 12th day of the reaction, the biodiesel yield of methanol was 83 wt%, the highest biodiesel yield among the three alcohols, and the biodiesel yield using ethanol and butanol was 69 wt%. .

Therefore, it was concluded that methanol is the most suitable alcohol for this experiment.

Example  1- (2) Rice bran  Effect of Reaction Temperature on Biodiesel Synthesis

The effect of reaction temperature on the yield of biodiesel during biodiesel synthesis using rice bran was investigated. The temperature range in this experiment ranged from 20 ° C to 70 ° C. At this time, the molar ratio of fat (fatty acid) and methanol in rice bran was 1: 2 and water content in rice bran was 12%.

Figure 4 shows the effect of the reaction temperature on the yield of biodiesel during biodiesel synthesis reaction using rice bran. As can be seen in FIG. 4, biodiesel yield was proportional to the increase in temperature from 20 ° C. to 50 ° C. for 9 days, and the yield dropped again at 60 ° C. and 70 ° C. But 50 In the case of ℃, the biodiesel yield no longer increased after 9 days of reaction, while in the case of 40 ℃, it continued to increase until 12 days of reaction to obtain a maximum yield of 83% by weight .

At 60 ° C. and 70 ° C., biodiesel yield increased up to 6 days of reaction, but biodiesel yield no longer increased after 6 days. In the case of 20 ° C. and 30 ° C., biodiesel yield was increased up to 12 days of reaction, but biodiesel yield no longer increased after 12 days. Thus 40 ° C. was shown as the optimum reaction temperature.

Example  1- (3) Rice bran  For biodiesel synthesis Rice bran  Effect of Mole Ratio of Oil Retention and Methanol

The effect of mole ratio between substrates on the yield of biodiesel was investigated in biodiesel synthesis using rice bran. The molar ratio of oil in the rice bran (fatty acid) and methanol in this experiment ranged from 1: 1 to 1: 3 (oil in the rice bran: methanol). At this time, the reaction temperature was 40 ℃, water content in the rice bran was 12%.

Figure 5 shows the effect of the molar ratio between the substrate on the biodiesel yield during biodiesel synthesis reaction using rice bran. The biodiesel yield increased as the molar ratio was increased except for 1: 3. However, in the case of 1: 1, after 2 days of reaction, the reaction rate was significantly slowed down. In the case of 1: 2 and 1: 2.5, the highest biodiesel yield was shown for the whole reaction period, and there was no significant difference between the two molar ratios. In the case of 1: 3, the reaction rate was the slowest for 2 days, but the biodiesel yield continued to increase until the 12th reaction and then decreased again at the 15th reaction. Therefore, the optimum molar ratio of 1: 2 was chosen in consideration of the effect and cost of methanol on enzyme denaturation. The maximum yield at 1: 2 was 83% by weight on day 12 of the reaction.

Example  1- (4) Rice bran  For biodiesel synthesis Rice bran  Effect of moisture content in

The effect of water content in rice bran on biodiesel yield was investigated during biodiesel synthesis using rice bran. The moisture content ranged from 1.6% to 24%. The water content of 1.6% was the minimum water content remaining when lyophilized rice bran. Reaction conditions at this time were the temperature of 40 degreeC, and molar ratio 1: 2 of rice fat (fatty acid) and methanol.

Figure 6 shows the effect of the moisture content in the rice bran in biodiesel synthesis reaction using rice bran. As can be seen in Figure 6, the moisture content in the rice bran increased from 1.6% to 12% biodiesel yield increased as the water content increases. However, biodiesel yield gradually decreased as the water content in rice bran increased to 18% or 24%. The maximum yield was 83% by weight on day 12 of reaction at 12% in moisture . Therefore, the optimum water content in rice bran was chosen as 12%.

Example  2-step reaction using 1- (5) moisture control

The maximum biodiesel yield was 83% by weight at the optimum conditions obtained above. At this time, 8.5% by weight of fatty acid and 1-2% by weight of acylglycerol (monoglyceride + diglyceride + triglyceride) remained in addition to the biodiesel. When the acid value of the water content was observed, the acid value increased with increasing moisture. Therefore, optimal conditions for 12 days to remove remaining fatty acids (temperature 40 ℃, molar ratio of fatty acid and methanol 1: 2, water content in rice bran 12%) and then reacted with methanol to remove the water by drying and re-add methanol 40 The reaction was carried out at 占 폚. As a result, as can be seen in Figure 7, all fatty acids are converted to biodiesel in 6 days of re-reaction, yielding a maximum yield of 96% by weight ( 100% conversion to biodiesel except for 4% by weight of non- saturated material ) Biodiesel was obtained.

Example  1- (6) High Peak From rice bran  Biodiesel Synthesis

Rice bran lipase has a very high hydrolysis titer. According to Siti Zullaikah (2005), free fatty acids in rice bran begin to increase rapidly within an hour after milling and increase by about 5% per day. In particular, the free fatty acid content in rice bran increases with higher temperature and longer storage period. Therefore, the degree of biodiesel synthesis was investigated using rice bran with high free fatty acid content.

The initial acid value of the oil in the rice bran used in this experiment was 100 (50% free fatty acid). As a result of reacting the rice bran oil (fatty acid) with methanol at a molar ratio of 1: 2, a reaction temperature of 40 ° C., and a water content of 12%, as shown in FIG. 6, a yield of 78% by weight was obtained at day 12 of the reaction.

Comparative Experiment  One: From rice bran  Synthesis of Biodiesel Using Isolated Lipase Extracts

Since the method for synthesizing biodiesel using rice bran according to the present invention is based on rice lipase which is an enzyme in rice bran, it was intended to check whether biodiesel can be synthesized by separating such rice bran lipase. Thus, biodiesel was synthesized using lipase extract from which lipase was separated from rice bran.

First, rice bran of the rewarding variety was extracted with hexane to obtain skim rice bran. To degreasing rice bran, potassium phosphate buffer (50 mmol mM, pH 7.0) corresponding to 8 times the weight of degreasing rice bran is stirred for 30 minutes. Centrifuge and collect the supernatant separately, add fresh potassium phosphate buffer to the lower layer and stir for 30 minutes. Repeat the above four times. The supernatant, that is, crude lipase extract and waste cooking oil were added in a 1:10 weight ratio, and methanol was added in two times the corresponding mole (mol) of waste cooking oil and reacted at 50 ° C. for 3 hours. As a result, in Comparative Example 1, no biodiesel was synthesized, and the yield was 0% by weight.

Example  2: degreasing Rice bran  Biodiesel Synthesis

This experiment was carried out to check whether the synthesis of biodiesel according to the method of the present invention is possible even when degreasing rice bran which has undergone milking process to obtain rice bran oil.

First, in order to prepare a degreasing rice bran to be used in the experiment, 500 mL of a solvent was added to 100 g of rice bran, followed by a 20 min agitation, and a degreasing process was performed four times. The solvent contained in the extracted skim rice bran was removed from the fume hood at room temperature for at least 12 hours.

Biodiesel was synthesized from various fats and oils using degreasing rice bran prepared through the above process, and the process is as follows. In a 1 L polypropylene bottle, a 10-25% fat or oil was added to 100 g of degreasing rice bran together with hexane, and then hexane was removed using a rotary vacuum evaporator to uniformly disperse the fat or oil in the degreasing rice bran. Thereafter, the remaining hexane was removed by evaporation in a fume hood at room temperature. To adjust the optimum moisture and methanol content in the rice bran added fat or oil, a certain amount of water and methanol were added and dispersed. Samples made through this process were synthesized by reacting in a thermostat maintained at a constant temperature.

Example  2- (1) Degreasing depending on the type of degreasing solvent Rice bran  Biodiesel yield comparison

In order to determine the effect of the type of solvent used for degreasing on biodiesel synthesis using degreasing rice bran, the degreasing rice bran was obtained in the same way using hexane, chloroform, diethyl ether and acetone as solvents, and soybean oil using enzymes in rice bran. The degree of synthesis of biodiesel was compared. The reaction was carried out by adding a certain amount of oil, methanol and water to degreasing rice bran degreased with various solvents. Namely, the reaction conditions were 15% by weight of fat or oil (soybean oil), 12% water content in rice bran, molar ratio 1: 2 (added soybean oil (fatty acid): methanol), and a temperature of 40 ° C.

9 is a graph showing the effect of the type of solvent used for degreasing on biodiesel synthesis using degreasing rice bran. As can be seen in FIG. 9, on the 9th day of the reaction, the yield of biodiesel was hexane (88.71 wt%), chloroform (83.42 wt%), ethyl ester (78.60 wt%), acetone (77.89 wt%) appear. Therefore, degreasing rice bran made with hexane showed the highest yield for biodiesel synthesis.

Example  2- (2) Biodiesel Synthesis by Oil Type

In order to determine the effect of biodiesel synthesis yield on the type of oil added during biodiesel synthesis using skim rice bran, vegetable oil (soybean oil, canola oil), animal oil (lard), palm oil, palm oil distillate, waste cooking oil The yield of biodiesel was compared using acid oil. Reaction conditions were 15 weight% of fats and oils, molar ratio 1: 2 of fats and oils (fatty acid basis), and methanol, reaction temperature 40 degreeC, and water content 12%. The degreasing rice bran used at this time was the degreasing rice bran degreased with hexane.

Figure 10 shows the synthesis yield of biodiesel according to the type of fats and oils added during biodiesel synthesis using degreasing rice bran. As can be seen in Figure 10, on day 12 of the reaction, 90.43% by weight (soybean oil), 90.65% by weight (canola oil), 91.36% by weight (rad), 91.92% by weight (palm oil), 87.15% by weight (palm oil distillation), respectively Water: fatty acid content 98%>), 87.29% by weight (waste cooking oil; fried oil), 80.02% by weight (acid oil).

Example  2- (3) degreasing Rice bran  Effect of Oil Addition on Biodiesel Synthesis

An experiment was conducted to derive the optimum conditions by analyzing the effect of addition oil retention and the molar ratio of methanol on biodiesel synthesis yield in the synthesis of skim rice bran. At this time, the fat or oil added to skim rice bran was used as a representative vegetable oil. Soybean oil was added to skim rice bran to prepare soybean oil-containing rice bran having 10, 15, 20, 25% (fat percentage calculated by the amount of fat / oil skimmed + weight of skim rice + oil). To this, 1 mol, 2 mol, and 3 mol of methanol were added based on fats and fats, and biodiesel yields were measured at optimum temperatures and moisture content (40 ° C., 12%) in the rice bran.

Figure 11 shows the effect of the content of soybean oil added to degreasing rice bran and the molar ratio of methanol according to the biodiesel synthesis. In the case of 10% fat or oil addition, a molar ratio of 1: 3 was optimal, and a yield of 89% by weight was obtained on the 9th day of the reaction. In the case of 15% fat or oil, the molar ratio of 1: 2 was optimal, and a yield of 90% by weight was obtained on the 12th day of the reaction. In the case of 20% fat or oil addition, a molar ratio of 1: 1 was optimal, and a yield of 94% by weight was obtained on the 27th day of the reaction. In the case of 25% of the oil-fat addition amount, the yield of 83 weight% was obtained on the 27th reaction.

Example  2- (4) Degreasing  About biodiesel synthesis Rice bran  Effect of Mole Ratio of Oil Retention and Methanol

The effect of the molar ratio between the substrates on the biodiesel synthesis at 15% fat or oil was shown in FIG. 12 according to the reaction time. The molar ratios performed ranged from 1: 1 to 1: 3 (oil retention in rice bran: methanol). At this time, the reaction temperature was 40 ℃, water content in the rice bran was 12%. The yield of biodiesel according to the molar ratio was as follows. Biodiesel yield was proportional to the molar ratio increase of molar ratio 1: 1 to 1: 2, and 1: 3 fell from 1: 2.5. However, in the case of 1: 1, after 2 days of reaction, the reaction rate was significantly slowed down. The highest biodiesel yields were found for 1: 1.5 and 1: 2 for 6 days, whereas 1: 2 did not increase for 1: 2 after 9 days.

Therefore, the optimum molar ratio was selected to be 1: 2 in consideration of the maximum yield and the effect and cost of methanol on enzyme denaturation. The maximum yield at 1: 2 was 93% by weight on day 15 of the reaction .

Example  2- (5) Degreasing  Effect of reaction temperature on biodiesel synthesis

13 shows the effect of the reaction temperature on the yield of biodiesel during biodiesel synthesis by the rice bran autoenzyme. The temperature range in this experiment ranged from 30 ° C to 60 ° C. At this time, the molar ratio of fat and oil in rice bran and methanol was 1: 2 and water content in rice bran was 12%.

The yield of biodiesel according to the reaction temperature was as follows. The biodiesel yield was proportional to the temperature increase from 30 ° C. to 40 ° C., and at 50 ° C. or higher the yield decreased again with increasing temperature. 50 For temperatures above 캜, biodiesel yield no longer increased after 9 days of reaction, while for temperatures below 40 캜, it continued to increase until reaction 15. At 40 ° C., the reaction rate was the fastest and biodiesel yield maximum (93 wt% on day 15 of reaction) was obtained, and 92 wt% on day 12 of reaction.

Thus, 40 ° C. was found to be the optimum reaction temperature.

Example  2- (6) Degreasing  About biodiesel synthesis Rice bran  Effect of moisture content in

The effect of moisture content in rice bran on biodiesel synthesis is shown in FIG. 14 according to reaction time. The moisture content ranged from 0.96% to 24%. The water content of 0.96% was the minimum water content remaining when lyophilized rice bran. Reaction conditions at this time were the temperature of 40 degreeC, and molar ratio 1: 2.

The yield of biodiesel according to moisture content in rice bran was as follows. Biodiesel yield increased with water content from 0.96% to 12%. However, biodiesel yield gradually decreased as the water content in rice bran increased to 18% or 24%. The initial reaction rate was maximum at 12% moisture, and biodiesel yields at 6% and 12% moisture were not significantly different on day 15 of the reaction. In addition, the initial moisture content in the rice bran was 12%, and considering the cost and time, 12% moisture was selected as the optimum water content in the rice bran. A maximum moisture content of 93 wt% was obtained on the 15th day of the reaction, and a yield of 92 wt% was obtained on the 12th day of the reaction.

Example  2- (7) Degreasing  Degreasing under optimum conditions for biodiesel synthesis Rice bran  Lipase Activity Measurement

Optimum conditions measured in Examples 2- (4) to 2- (7) (oil content 15%, reaction temperature 40 ℃, molar ratio of fat and oil and methanol 1: 2, water content 12%, reaction time 12 days) The activity of the enzyme was measured from biodiesel yield. In addition, in order to determine the effect of glycerol on the inhibition of enzyme activity, the yield of biodiesel was compared according to the number of reactions by dividing the reaction between removing glycerol generated during the reaction with acetone and not removing glycerol after each reaction. Acetone was used as a solvent for removing glycerol, and after degreasing in the same manner as in Example 2 for each batch of reaction, a stirring process was performed three times for 20 minutes at a volume of 5 times the weight of rice bran. Thereafter, the mixture was twice subjected to a stirring process for 20 minutes using hexane in a volume of 5 times the weight of rice bran. The subsequent process was performed in the same manner as in Example 2.

As a result of not removing glycerol (FIG. 15 control curve), as the reaction was repeated, biodiesel yield was steadily decreased after 2 reactions, and then rapidly decreased after 8 reactions. On the other hand, as a result of removing glycerol (Fig. 15 treatment group curve), the reaction yielded a constant biodiesel yield up to 3 times, and then gradually decreased to 9 times, and then rapidly decreased thereafter.

Therefore, it was confirmed that the removal of glycerol produced during the reaction from the degreasing rice bran lipase was effective in maintaining the activity of the enzyme and extending the use period.

Example  3: In a solvent system Rice bran  Biodiesel Synthesis with Catalyst

3 g of rice bran or degreasing rice bran is placed in a 50 mL Erlenmeyer flask, methanol is added so that the molar ratio of methanol to fats and oils contained in the sample bran is 1: 2, 10 mL of hexane is added, and the mixture is sealed and shaken with an orbital water bath (orbital water). The reaction was performed at 40 ° C. while stirring at 300 rpm in a bath shaker to synthesize biodiesel.

In a solvent-based reaction system using hexane as a reaction medium, when the reaction was performed with rice bran as a catalyst, oil in the rice bran and methanol as a raw material, a yield of 57% by weight was obtained on the 12th day of the reaction, and the acid value was zero. When degreasing rice bran was used as a catalyst and vegetable oil (soybean oil) was reacted with methanol as a raw material, a yield of 52% by weight was obtained at day 12 of the reaction (Fig. 16).

Claims (14)

Dispersing alcohol in rice bran, and mixing the mixture of rice bran and alcohol in a reactor to synthesize biodiesel,
Separating the synthesized biodiesel,
The rice bran has a moisture content of 1.6 to 24%
Production method of biodiesel using rice bran.
The method of claim 1,
The production method,
After adding the fat or oil to the rice bran obtained after the biodiesel separation and dispersing the alcohol, it is left in the reactor to synthesize biodiesel, and further comprising the step of separating the synthesized biodiesel,
The process is repeatable 1 to 10 times
Production method of biodiesel using rice bran.
The method of claim 1,
If the rice bran is degreasing rice bran,
After adding fats and oils to skim rice bran and dispersing alcohol, these mixtures were left to synthesize biodiesel,
Comprising separating the synthesized biodiesel
Production method of biodiesel using rice bran. The method of claim 3,
The production method,
After adding the fat or oil to the rice bran obtained after the biodiesel separation and dispersing the alcohol, it is left in the reactor to synthesize biodiesel, and further comprising the step of separating the synthesized biodiesel,
The process is repeatable 1 to 10 times
Production method of biodiesel using rice bran.
The method of claim 1,
The rice bran has an acid value of 0 to 200
Production method of biodiesel using rice bran.
The method according to any one of claims 2 to 4,
The fats and oils are vegetable oils, animal oils, algae oil, oil-derived microbial oil, oil distilllate fatty acid, waste oil or acid oil (Acid oil)
Production method of biodiesel using rice bran.
The method according to any one of claims 2 to 4,
The fats and oils are added in a ratio of 5 to 25% of the total weight of the fat and rice bran
Production method of biodiesel using rice bran.
The method according to any one of claims 1 to 5,
The alcohol is methanol, ethanol or butanol
Production method of biodiesel using rice bran.
The method according to any one of claims 1 to 5,
The alcohol is dispersed in 0.1 to 10 parts by weight based on 100 parts by weight of rice bran
Production method of biodiesel using rice bran.
The method according to any one of claims 2 to 5,
Synthesis of the biodiesel is carried out under the condition that the molar ratio of fats and oils: 1: 1 to 1: 3.
Production method of biodiesel using rice bran.
The method according to any one of claims 1 to 5,
Synthesis of the biodiesel is made at 20 to 70 ℃
Production method of biodiesel using rice bran.
delete The method according to any one of claims 1 to 5,
The production method further includes the step of separating the biodiesel from the reactants obtained after the synthesis of the biodiesel, removing the water and alcohol from the residue and then dispersing the alcohol again, and standing in the reactor to synthesize biodiesel. That
Production method of biodiesel using rice bran.
The method of claim 1,
Synthesis of the biodiesel is carried out in a solvent
Production method of biodiesel using rice bran.

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