KR101330835B1 - A method obtaining fatty acids from biodiesel-derived waste glycerol - Google Patents

Abstract

The present invention relates to a method for recovering fatty acids from spent glycerol containing fatty acid salts. More specifically, the present invention relates to a method for recovering higher fatty acids from waste glycerol which is a by-product of a biodiesel production process for use as a raw material for fine chemicals such as detergents or surfactants.
The method includes converting a fatty acid salt into a fatty acid by adding an acid to a mixed solution containing glycerol and a fatty acid salt (S1), and adding an organic solvent to the mixed solution containing the fatty acid to dissolve the fatty acid in the organic solvent. (S2), separating the organic solvent in which the fatty acid is dissolved from the mixed solution (S3), and removing the pigment and impurities from the dissolved fatty acid in the organic solvent (S4).

Description

A method for recovering fatty acids from waste glycerol, a by-product of the biodiesel production process {A METHOD OBTAINING FATTY ACIDS FROM BIODIESEL-DERIVED WASTE GLYCEROL}

The present invention relates to a method for recovering fatty acids from spent glycerol containing fatty acid salts. More specifically, the present invention relates to a method for recovering higher fatty acids from waste glycerol which is a by-product of a biodiesel production process for use as a raw material for fine chemicals such as detergents or surfactants.

Due to the depletion of petroleum resources and the demand for clean energy, biodiesel production is rapidly increasing at home and abroad. For example, US biodiesel production surged from 2 million gallons in 2000 to 230 million gallons in 2006, and in Korea, the amount of biodiesel sold during 2006 was 26,826 kL, about 3.3% of US production. to be. In the biodiesel production process, oil (mostly edible oil), methanol, and a base catalyst (KOH or NaOH) are introduced into the reactor to produce biodiesel, which is a methyl ester of fatty acid, by transesterification. On the other hand, fat is a fatty acid and glycerol combined form, it is broken down into fatty acids and glycerol by the esterification reaction to produce glycerol as a by-product. In addition, some of the fatty acids produced in the side reaction react with the base catalyst to be converted into the form of fatty acid salts. About 10 kg of glycerol is produced as a byproduct for every 100 kg of biodiesel produced. The acid and base catalyst used in the biodiesel production process are mixed with the waste glycerol to be present as a high concentration salt, and the by-product fatty acid salt is not removed in the separation process. Methanol, a biodiesel component, and the like.

By-product waste glycerol is not only low-purity (60-80%) but also dark brown with abomination and cannot be used directly as a petrochemical or cosmetic raw material. High-purity refining process is required, but the price of high-purity glycerol has recently been falling, and waste glycerol more than the demand is generated and refined and sold is losing price competitiveness. Therefore, waste glycerol gradually loses its use, and it is urgent to prepare a countermeasure to deal with it. Since the landfill of excess waste glycerol may cause secondary environmental pollution, research to utilize it rather than dispose of it has become a hot issue worldwide. Most studies have recently been actively conducted to produce ethanol, hydrogen, succinic acid, lactic acid, etc. by microbial fermentation using unpurified glycerol as a microbial substrate. However, fatty acid salts, etc. present in the waste glycerol inhibit the microbial growth, there is a problem that the fermentation efficiency is not high. In addition, microorganisms consume glycerol, but the fatty acid salt consumption efficiency is not high, it is pointed out that the fatty acid salt is still generated as waste even after the end of the culture. Therefore, there is a trend to use pretreated crude glycerol from which fatty acids present in excess (about 17%) in crude glycerol are removed as a microbial substrate. However, there is still a problem in the treatment of fatty acid salts generated as waste.

It is an object of the present invention to provide a method for recovering high-purity higher fatty acids from fatty acid salts contained in waste glycerol, a by-product of the biodiesel production process. Moreover, an object of this invention is to provide the method of collect | recovering the fatty acid from which the impurity or the pigment was removed so that it can be used as a material of cleaning agent.

The present invention has been made in order to solve the above problems to convert the fatty acid salt to fatty acid by adding an acid to the mixed solution containing (S1) glycerol and fatty acid salt, (S2) mixed solution containing the fatty acid Dissolving the fatty acid in an organic solvent by adding an organic solvent to the organic solvent, (S3) separating the organic solvent in which the fatty acid is dissolved from the mixed solution, and (S4) dissolving pigments and impurities from the fatty acids dissolved in the organic solvent. It provides a fatty acid recovery method comprising the step of removing.

It is preferable to add the said acidic aqueous solution in the same amount as the said mixed solution.

The acidic aqueous solution may be selected from aqueous hydrochloric acid, aqueous sulfuric acid and nitric acid.

The organic solvent is preferably at least one selected from the group consisting of hexane, ether, isobutyl acetate and CHCl ₃ .

The recovering of the fatty acid is preferably performed by distillation under reduced pressure of an organic solvent in which fatty acid is dissolved.

In addition, the present invention may further perform the step of recovering the fatty acid by performing a reduced pressure distillation of the organic solvent in which the fatty acid is dissolved before or after the step (S4).

Removing the pigment and impurities from the recovered fatty acid may be made by treating activated clay with the recovered fatty acid. The step of treating the pigments and impurities is treated with activated clay in a fatty acid solution having a color OD ₃₇₅ 20 to 40 so that the value of the color OD ₃₇₅ of the fatty acid after treatment is 0.1 or less. Treatment of the pigment and impurities may be performed by adding 10% to 60% by weight relative to 100% by weight of a fatty acid solution having a color of OD ₃₇₅ 20 to 40.

The mixed solution is preferably a waste glycerol solution generated in the biodiesel production process.

The fatty acid recovery method according to the present invention provides a method for recovering a higher fatty acid from a lower waste glycerol which is a by-product of a biodiesel production process, and using this as a raw material, it is possible to manufacture fine chemical products such as skin cleaners and surfactants. As a result, synergies can be expected to reduce raw materials and prevent secondary environmental pollution.

1 is a flow chart showing each step of the fatty acid recovery method of the present invention.
Figure 2 schematically shows how the fatty acid moves to the organic solvent layer.
Figure 3 shows the fatty acid solution recovered with the organic solvent removed.
4 and 5 illustrate experimental data performed to search for the optimal ratio of chromaticity (OD ₃₇₅ ) of the fatty acid solution and the amount of activated clay added when the activated clay is removed by adding activated clay to the recovered fatty acid. It is.
Figure 6 is a photograph comparing the color of the fatty acid before and after the addition of activated clay.
Fig. 7 shows gas chromatograph peaks showing the composition of fatty acids before and after treatment with activated clay.
Figure 8 shows the experimental results confirming the peroxide reduction in fatty acid before and after the treatment of activated clay.

The present invention relates to a method for recovering fatty acids containing large amounts of unsaturated fatty acids, linolenic acid and / or oleic acid, which can be used as raw materials for skin cleansers and fine chemicals from a mixed solution containing glycerol and fatty acid salts.

In particular, the present invention is that the mixed solution is a waste glycerol solution which is a by-product generated from the biodiesel production process. Approximately 10 kg of waste glycerol solution is produced as a by-product per 100 kg of biodiesel produced in the general biodiesel production process. The waste glycerol solution contains acid and base catalysts used in the biodiesel production process, so that the fatty acid is a high concentration of salt. exist. The fatty acid salt is known to be present in a proportion of 15% to 20% by weight in 100% by weight of the waste glycerol solution. In addition, the waste glycerol solution includes methanol and biodiesel components not removed in the separation process. The present invention is conceived to recover a higher fatty acid from the fatty acid salt contained in the waste glycerol to provide as a raw material such as cleaning agent.

For convenience of explanation, the mixed solution will be described as a waste glycerol solution, for example, a by-product generated in the biodiesel production process. However, the present invention is not limited thereto and those skilled in the art will be able to assume various mixed solutions within the scope of the present invention.

Hereinafter, a fatty acid recovery method of the present invention will be described in detail with reference to FIG. 1, which is a flowchart schematically illustrating a fatty acid recovery method.

The waste glycerol solution contains glycerol and a fatty acid salt and has a pH of about 11 to about 12, wherein the fatty acid is present in the form of a fatty acid salt, and the fatty acid is contained in the range of 15% to 20% by weight of 100% by weight waste glycerol. do.

The first step of the fatty acid recovery method according to the invention is to first add an acid to the waste glycerol solution. The addition of the acid lowers the pH of the solution to convert fatty acid salts into fatty acids (S1). The acid may be an inorganic acid or an organic acid, preferably hydrochloric acid, nitric acid or nitric acid. However, the present invention is not limited thereto, and any pH can be used as long as the pH of the basic waste glycerol solution can be used to form a fatty acid.

Preferably, the same amount of water as the prepared solution is added to the waste glycerol solution, and then acid is added, or an acidic aqueous solution prepared in advance is added to the waste glycerol solution to prepare an acidic waste glycerol solution.

In the step (S1), a waste glycerol aqueous solution having a pH of about 1 to about 2 is obtained, and the fatty acid salt in the waste glycerol solution is converted into a fatty acid.

Next, an organic solvent is added to the waste glycerol aqueous solution (S2). The amount of the organic solvent added is preferably the same amount as the prepared waste glycerol aqueous solution. For convenience of explanation, an organic solvent is added to the waste glycerol aqueous solution as a second mixed solution. The second mixed solution may be separated into an aqueous solution layer and an organic solvent layer. The resulting fatty acids have low solubility in water while high solubility in organic solvents. Therefore, in the second mixed solution, the fatty acid moves to the organic solvent layer, and the remaining inorganic substances and methanol remain in the aqueous solution layer. Figure 2 shows the schematic of the migration of the fatty acid in the second mixed solution to the organic solvent layer. The organic solvent may representatively use hexane, ether, isobutyl acetate and CHCl ₃ . However, the present invention is not limited thereto, and any solvent may be used as long as it can selectively dissolve only fatty acids contained in the first mixed solution.

Thereafter, the organic solvent layer including the fatty acid in the second mixed solution is separated from the aqueous solution layer (S3).

The fatty acid is dissolved in the organic solvent layer separated from the second mixed solution, which is called a first fatty acid solution for convenience. The first fatty acid solution is dark brown due to untreated impurities derived from the first mixed solution. Therefore, it is difficult to use fatty acids in the first mixed solution directly as raw materials for the preparation of skin cleaners and fine chemicals. Therefore, it is necessary to perform the step (S4) of removing impurities such as pigments from the first fatty acid solution.

According to one specific embodiment of the present invention, activated clay is used to remove impurities and pigments from the first fatty acid solution. The activated clay has a high surface area and an excellent adsorption capacity, and is effective for removing impurities. The activated clay is also called kaolin.

The active clay is preferably acidic clay. The activated clay has a water content of 6 to 10%. The particle size is preferably 200 mesh or less. In addition, the larger the surface area, the higher the adsorption force, so the specific surface area is preferably 200 to 250 m ² / g.

Impurity removal efficacy of the activated clay tends to increase linearly with the amount added. On the other hand, impurity removal effects according to reaction time or reaction temperature of activated clay and fatty acid are insignificant.

Accordingly, the present invention removes impurities from the first fatty acid solution to recover the fatty acid solution (hereinafter referred to as the second fatty acid solution) having a colorless and transparent appearance suitable for use as a raw material for skin cleansers and fine chemicals. It provides a preferred amount range.

After treating activated clay with the first fatty acid solution and analyzing the absorbance using a UV / VIS spectrophotometer, the absorbance value after the treatment is drastically decreased in comparison with the treatment in the wavelength range of about 350 nm to about 400 mm. On the basis of this, it is possible to secure the most effective amount of activated clay added to remove impurities from the first fatty acid solution. Preferably, among the points at which the decolorization degree of the first fatty acid solution is 100%, an easy operation condition may be selected as an optimum point (see FIGS. 4 to 5). For example, a solution with a high chromaticity (absorbance value at 375 nm, OD ₃₇₅ of 50 or more, measured by UV / VIS spectrophotometer) among several points with 100% decolorization has a high viscosity from the solution after decolorization. It is difficult to separate active clay.

According to one preferred embodiment, activated clay is added to the first fatty acid solution obtained in the step (S3) so that the chromaticity (OD ₃₇₅ , as measured by UV / VIS spectrophotometer) is 0.1 or less after treatment.

Specifically, the first fatty acid solution obtained in the step (S3) is adjusted by adding or subtracting an appropriate organic solvent such as hexane such that the absorbance (OD ₃₇₅ ) value is about 20 to 40, and 100 wt% of the first fatty acid solution is added thereto. 10 to 60% by weight of active clay is added as a reference.

The conditions presented above are advantageous because the amount of solvent such as hexane used for dilution can be reduced by treating concentrated fatty acids, so that the amount of waste organic solvent generated as an economic benefit and pollution source can be reduced. In addition, the first fatty acid solution in the above range may exhibit a degree of decolorization of 99% or more. Figure 6 shows the first fatty acid solution before treatment with activated clay and the second fatty acid solution treated with activated clay under optimum conditions. The fatty acid solution before treatment is dark brown but the fatty acid solution treated with activated clay has a colorless and transparent appearance.

If necessary, the step of recovering the fatty acid from the first fatty acid solution before performing the step (S4) and / or recovering the fatty acid from the second fatty acid solution after the step (S4). The recovery step may be performed by distilling the organic solvent layer under reduced pressure to remove the organic solvent from the fatty acid solution. Figure 3 shows the fatty acids recovered after removing the organic solvent in the first fatty acid solution.

If the recovery step is performed before step (S4), after adjusting the OD ₃₇₅ to 20 to 40 by adding or subtracting an organic solvent such as hexane to the recovered fatty acid, step (S4) is preferably performed.

Example

(1) fatty acid solution recovery

50 ml of a waste glycerol solution generated during the biodiesel production process was prepared. The pH of the waste glycerol is 11 and the composition is shown in Table 1 below. The fatty acid salts were 80% higher fatty acids having C18 or more, most of which were unsaturated fatty acids oleate (C18: 1) and linoleate (C18: 2).

Furtherance content(%) Glycerol Content 80 K 1.1 Na 0.03 MeOH 14.2 Fatty acid salt 17.4

50 ml of water was added to the waste glycerol solution to prepare an aqueous waste glycerol solution, and then, hydrochloric acid was added to pH 1 to add an aqueous hydrochloric acid solution (purity, 35%) to adjust the acidity. 50 ml of hexane was added to the waste glycerol solution to transfer fatty acids to the hexane layer, and the aqueous layer was separated and removed. The first fatty acid solution was recovered by removing hexane through distillation under reduced pressure in the hexane layer.

(2) decolorization of fatty acid solution

OD ₃₇₅ which shows the chromaticity of a 1st fatty acid solution by adding or subtracting hexane to the fatty acid solution obtained above. The value was set to 20. After adding 3.5 g of activated clay to 10 ml of the first fatty acid solution, the mixture was stirred for 30 minutes at 100 rpm and room temperature. A colorless transparent second fatty acid solution was recovered from above.

Color analysis of the second fatty acid solution (absorbance value at 375 nm, measured by UV / VIS spectrophotometer, OD ₃₇₅ ) showed 99.7% of decolorization.

Test Example

(1) Analysis of impurities removal effect

Since activated clay is an adsorbent, it is necessary to confirm not only because it adsorbs color substances but also fatty acids. Therefore, gas chromatography analysis was performed to confirm the change of fatty acid content in the treated first and second fatty acid solutions. The initial temperature was 140 ° C. (5 minutes) and warmed up to 240 ° C. at a rate of 4 ° C. per minute. Helium was used as the carrier gas and was set at a speed of 20 cm per second. The injection temperature was 240 degreeC and the detection temperature was 260 degreeC. The amount of the sample injected on the basis of 100: 1 was 1 μl (240 ° C.). First, the existence time of each fatty acid was confirmed by comparing the retention time of each fatty acid with the fatty acid standard solution, and the area change was calculated to investigate the loss of fatty acids. 7 is a result of confirming the change of fatty acid content before and after active clay treatment. As shown in Table 2, about 38% of fatty acids were also lost during the treatment of activated clay. In addition, changes in the peroxide content of the first and second fatty acid solutions were measured, and after removal of impurities, the H 2 O 2 content and the organic peroxide content decreased by about 86% and 80%, respectively (FIG. 8).

These results indicate that activated clay not only partially adsorbs fatty acids but also completely adsorbs colored materials, and effectively removes oxygen radical-containing substances such as peroxides, which have a fatal effect on the human body or chemical reactions. Can be.

fatty acid area Area change amount (%) Before processing After processing Palmitic acid 1496 ± 91 946 ± 28 -37 ± 3.7 Palitolene Phosphate 100 ± 5 63 ± 1 -37 ± 4 Stearic acid 316 ± 156 327 ± 14 18 ± 45 Oleic acid 2722 ± 496 1673 ± 35 -37 ± 12 Linolenic Acid (C18: 2) 3652 ± 228 2301 ± 93 -37 ± 4 Linolenic Acid (C18: 3) 495 ± 34 310 ± 13 -37 ± 4.2 Behein acid (C22: 0) 33 ± 2 21 ± 1 -38 ± 2

(2) Review of raw material conformity of recovered fatty acids

The conformity of raw materials of the second fatty acid solution according to Example 1 was examined. Lead, arsenic and mercury content must be below the baseline to be used as a cleaning material. Table 2 shows the contents of the components present in the second fatty acid solution according to a recognized test method. The lead content was 2.1 ppm, which is much less than the baseline of 20 ppm. Arsenic content represented much less than the measurable range. That is, according to the test method, when the reaction reagent is added, the sample containing arsenic of 2 ppm or more as a reference value turns yellow, but the sample does not show any color change. Mercury was not detected at all. These results indicate that all fatty acid samples recovered and purified from waste glycerol pass the set standard and are suitable as skin cleanser raw materials.

Review of raw material conformity of recovered fatty acids Evaluation item unit Results standard ( specification ) Assessment Methods Heavy metal (lead) content ppm 2.1 20 Cosmetic Standards and Test Methods
(Notice of KFDA) Arsenic content ppm fitness 2 Cosmetic Standards and Test Methods
(Notice of KFDA) Mercury content ppm Not detected One Food Code
Test method

Claims (8)

(S1) converting the fatty acid salts into fatty acids by adding an acid to the mixed solution containing glycerol and fatty acid salts;
(S2) dissolving the fatty acid in the organic solvent by adding an organic solvent to the mixed solution containing the fatty acid;
(S3) separating the organic solvent in which the fatty acid is dissolved from the mixed solution containing glycerol; And
(S4) recovering the fatty acid by distillation under reduced pressure of the organic solvent in which the fatty acid is dissolved;
Fatty acid recovery method comprising a.
The method of claim 1,
The acid added to the mixed solution is selected from hydrochloric acid, sulfuric acid and nitric acid.
The method of claim 1,
The organic solvent is characterized in that at least one solvent selected from the group consisting of hexane, ether, ethyl acetate and CHCl ₃ , fatty acid recovery method.
The method of claim 1,
Removing a pigment and impurities from the recovered fatty acids; fatty acid recovery method further comprising.
5. The method of claim 4,
Removing the pigment and impurities from the recovered fatty acid is a fatty acid recovery method, characterized in that made by treating activated clay with the recovered fatty acid.
5. The method of claim 4,
The step of treating the pigment and impurity is a fatty acid recovery method of treating the activated clay to a fatty acid having a color OD ₃₇₅ 20 to 40 so that the value of the color OD ₃₇₅ of the fatty acid after the treatment is 0.1 or less.
5. The method of claim 4,
Removing the pigment and impurities from the recovered fatty acid is a fatty acid recovery method characterized in that the addition of 10 to 60% by weight of activated clay relative to 100% by weight of fatty acids having a color of OD ₃₇₅ 20 to 40.
The method of claim 1,
The 'mixed solution containing glycerol and fatty acid salts' is a waste glycerol solution generated in the biodiesel production process, fatty acid recovery method.

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