KR20100118691A - Method for refining waste edible oil - Google Patents

Abstract

PURPOSE: An environment-friendly removal method of free fatty acid is provided to remove the necessity of a large-scale wastewater disposal plant, and to prevent the environmental pollution by waste water. CONSTITUTION: An environment-friendly removal method of free fatty acid comprises the followings steps: mixing waste edible oil with a sodium hydroxide solution, for neutralizing the free fatty acid; firstly removing impurities from the mixture by settling or centrifuging remained sodium hydroxide, foots of neutralized free fatty acid, and other foreign materials; and adding an adsorber and stirring to remove remain impurities.

Description

Method for removing free fatty acids from waste vegetable oils of animals and plants {Method for refining waste edible oil}

The present invention relates to a method for removing free fatty acids from waste cooking oil containing a large amount of free fatty acids, and more specifically, it is possible to neutralize (salt) free fatty acids using an alkali deoxidation method and then remove and reuse them for industrial use. A method for producing industrial fats and oils.

In a restaurant such as a chicken shop or a bakery, especially a food processing factory, a large amount of edible oils (including vegetable oils and animal fats and oils) are used for frying, and thus a large amount of waste cooking oil is generated. Waste oils that are discarded after food processing cannot be reused for food under legal regulations once they are classified as waste oils.

The waste cooking oil discarded after food processing contains a large amount of free fatty acids.

Free fatty acid (FFA) is a fatty acid produced by hydrolysis of fats. Normally, fats are triglycerides, which are triglycerides in which three molecules of fatty acids and one molecule of glycerol are ester-bonded. It occupies more than 99%. When such triglycerides are rancid or hydrolyzed due to external air contact, reaction with moisture at high temperatures, they are decomposed into fatty acids and glycerol. The decomposed fatty acids are called free fatty acids.

As a method of reusing waste cooking oil generated in large quantities throughout the industry, it is largely divided into a method of reproducing industrial oils for use as industrial raw materials and a method of reproducing fuels such as biodiesel fuel or boiler fuel.

Biodiesel oil is used as a vehicle fuel by reacting waste cooking oil with methanol under an acid or alkali catalyst to produce mono fatty acid methyl ester, thus decomposing not only free fatty acids but also triglycerides (triglycerides) and esterifying them with alcohol. It is distinguished from the industrial fats and oils production method which removes only free fatty acid except fat.

For industrial fats and oils, it is essential to efficiently remove only free fatty acids that adversely affect product quality while maintaining fat (usually triglyceride) properties. Free fatty acids contained in animal or vegetable fats or oils used in waste oil have various adverse reactions such as oxide production and thermal polymerization in the production of oil-based products, which have a huge negative effect on product quality and yield. The method was developed.

Korean Patent Publication No. 2001-0002402 discloses a method for treating edible oil or fat by using a strong basic or weakly basic anion exchange resin or by using a mixture of the anion exchange resin and activated carbon. However, the deoxidation method is limited to relatively small tablets, and has a disadvantage in that a purification treatment cost is high.

On the other hand, Korean Patent Publication No. 1992-002893 discloses a method of deoxidation using Pseudo monas sp., A microorganism which ingests and removes only free fatty acids in edible oils and fats, and US Patent US 5,532,163 discloses As a deoxidation method, US Pat. No. 4,957,758 discloses a method for refining fats and oils by a filter apparatus in French fries, and Japanese Patent Laid-Open No. 2007-145974 discloses a method for refining waste oil.

In the purification of edible oils and fats, the alkali deoxidation method is most widely used as a deoxidation method of oils and fats milked from oilseed seeds. Conventional alkali deoxidation method is a soap precipitated by neutralizing free fatty acid (R-COO ^- Na ⁺ , R-COO ^- K ⁺ ) with alkali such as sodium hydroxide (NaOH), potassium hydroxide (KOH), and then centrifuging or standing. It is a method of removing the flames and other impurities and water first, then washing with a large amount of hot water (about 80 ~ 90 ℃) in order to remove the remaining impurities such as the remaining soap, dried and deoxidized.

The process of the conventional alkali deoxidation method is shown in FIG.

The alkali deoxidation method can lower the free fatty acid content in fats and oils most efficiently, but the biggest disadvantage of this method is that the waste water is generated in the washing process that removes impurities such as soap by using a large amount of water. It may cause a problem, there is a problem such as the increase in the cost of a large place and waste water treatment for the installation of waste water treatment facilities. On the other hand, there is a method of purifying free fatty acids by spraying high temperature steam, but liquid oils with low stability to heat have disadvantages such as discoloration.

On the other hand, there is a method of using a deoxidizing agent such as magnesium as a physical deoxidation method, but compared to the alkali deoxidation method, the removal efficiency of free fatty acids is low, for example, to adjust the amount of free fatty acids in the frying to maintain a certain level of use of frying oil It is used in a limited and small size for the purpose of increasing the color or preventing the color from darkening during deep frying.

The present invention has been made to solve the problem that a large amount of water is used to remove soap and other impurities in the conventional alkali deoxidation method, environmental pollution occurs by removing free fatty acids efficiently without the washing step in the conventional alkali deoxidation method The aim is to provide a new alkaline deoxidation method that does not require large-scale wastewater purification.

2 is a process chart of the alkali deoxidation method according to the present invention.

Free fatty acid removal method of the waste cooking oil of the present invention for achieving the above object,

A neutralization step of neutralizing free fatty acids by mixing sodium hydroxide solution with animal and vegetable waste cooking oil; A primary impurity removal process for removing sodium hydroxide remaining after the reaction, the feet of neutralized fatty acid salts and other impurities by centrifugation or standing; And a secondary impurity removal step of removing the waste adsorbent after adsorbing the impurity by adding and stirring the adsorbent after removing the primary impurity.

In addition, the present invention may further include a drying step of removing the remaining water in order to increase the adsorption reaction efficiency before the adsorbent, after the primary impurity removal process.

In the present invention, "waste cooking oil" is a concept that includes vegetable oil, animal fats and oils that are thrown away after frying various foods at home, bakery, chicken shop or food processing factory. In the present invention, the free fatty acid content of the waste cooking oil is not limited, but is preferably applied to the waste cooking oil having a free fatty acid content of 1.5% or more.

The sodium hydroxide solution concentration used for the neutralization reaction of the free fatty acid is not limited, but it is preferable to use a high concentration solution, namely, Beome (Be) 10-30 °, more preferably 16 ° or more.

In the present invention, as the adsorbent, preferably, one or a mixture thereof selected from the group consisting of magnesium silicate, activated clay, aluminum silicate silicate, activated carbon, and diatomaceous earth may be used, more preferably magnesium silicate alone or magnesium silicate and Mixtures of activated clay may be used.

When used alone, the content of magnesium silicate is preferably used in an amount of 0.2 wt% to 3.0 wt%, more preferably 0.3 wt% to 2.0 wt%, based on the weight of the waste cooking oil. If the magnesium silicate is less than 0.3% by weight, the adsorption reaction efficiency is low and the removal of free fatty acid, soap powder and water is low. If it is added more than 3.0% by weight, the removal of free fatty acid, soap powder and water is good, but the manufacturing price is increased and economical Falls.

When the content of the activated clay is used alone, it is effective in terms of quality, such as color improvement, to use under reduced pressure rather than atmospheric pressure. However, there is a disadvantage in that a lot of energy is consumed to maintain the decompression. Activated clay under reduced pressure is preferably used 0.3 to 2.0% by weight when used alone. If the activated clay is less than 0.3% by weight, there is almost no removal effect. If the amount of activated clay is more than 2.0% by weight, the removal efficiency is good, but the amount of the waste adsorbent increases, and there is a problem that the filtration rate decreases when the filter is filtered.

In order to improve the problem, when mixed with activated clay and magnesium silicate and used as an adsorbent, atmospheric pressure reaction is possible, and there is an effect of color improvement without additional energy consumption. The mixing ratio may be mixed and used within the range of 0.3% to 3.0% by weight of magnesium silicate and 0.3% to 2.0% by weight of activated clay, but 0.5% to 2.0% of magnesium silicate in view of adsorbent cost or filtration rate, etc. It is preferable to use the mixture within the range of 0.3% to 0.7% by weight of activated clay. When mixed with magnesium silicate, when the content of activated clay is lower than 0.3% by weight, the efficiency decreases, and when it is 1.0% by weight or more, the free fatty acid content increases.

Moreover, it is preferable to make reaction temperature in the range of 60 degreeC-90 degreeC at normal pressure in an adsorption reaction. If the reaction temperature is 100 ° C. or more, the free fatty acid content may increase due to rancidity, thereby degrading the quality. And under reduced pressure, it is preferable to make reaction temperature react in the range of 100 degreeC-120 degreeC.

Removal of the waste adsorbent can use well-known filtration methods, such as a filter press.

The free fatty acid removal method of the present invention is a conventional washing process by removing impurities using magnesium silicate, activated clay or mixtures thereof as an adsorbent, instead of using a washing step that must be passed after alkali neutralization in the conventional alkali deoxidation method. It is environmentally friendly because there is no large amount of wastewater discharged, and there is no burden on wastewater treatment facilities.

Through the following examples will be described in more detail the waste cooking oil free fatty acid removal method of the present invention. This embodiment only describes a preferred embodiment of the present invention, the technical spirit of the present invention is not limited thereto.

Example 1 ① neutralization of sodium hydroxide, ② drying, ③ magnesium silicate adsorption

(1) 80 g of sodium hydroxide solution was added to 2,000 g of waste cooking oil containing high content of free fatty acid, mixed with a blender, and neutralized.

(2) Centrifugation was performed to separate layers of neutralized salts, foots such as soap powder, other impurities, and the water layer from the neutral layer of the upper layer.

(3) The separated neutral oil was heated under reduced pressure to remove residual water.

(4) 0.5% by weight (10g), 1.0% by weight (20g) and 2.0% by weight (40g) of magnesium silicate powder were added and mixed with a stirrer and reacted at 85 ° C. Industrial fats and fats were removed.

Example 2: ① sodium hydroxide neutralization, ② magnesium silicate adsorption

It was carried out in the same manner as in Example 1 except that the drying step after the primary impurity removal step was carried out to produce industrial fats and oils.

Example 3: ① sodium hydroxide neutralization, ② activated clay adsorption

The same method as in Example 1, except that the drying step after the first impurity removal step, 0.5 wt% (10g), 1.0% by weight (20g) and 2.0% by weight (40g) of activated clay, respectively, as an adsorbent Addition and adsorption produced industrial fats and oils.

Example 4: ① sodium hydroxide neutralization, ② magnesium aluminum silicate adsorption

The same method as in Example 1, except that the drying step after the primary impurity removal step, and 0.5 wt% (10g), 1.0 wt% (20g) and 2.0 wt% (40g) of magnesium aluminum silicate as an adsorbent, respectively Was added and adsorbed to produce an industrial fat or oil.

Example 5 ① neutralization of sodium hydroxide, ② adsorption of magnesium silicate / active clay mixture

In the same manner as in Example 1, except that the drying step after the first impurity removal step, 0.5% by weight (10g), 1.0% by weight (20g) of the same ratio mixture of magnesium silicate powder and activated clay as an adsorbent, respectively And 2.0 wt% (40 g) were added and adsorbed to produce an industrial fat or oil.

Comparative Example 1: prior art (① neutralization of sodium hydroxide, ② water washing)

(1) 80 g of sodium hydroxide solution was added to 2,000 g of waste cooking oil containing high content of free fatty acid, mixed with a blender, and neutralized.

(2) Centrifugation was performed to separate layers of neutralized salts, foots such as soap powder, other impurities, and the water layer from the neutral layer of the upper layer.

(3) The separated neutral oil was washed with 20 wt% (about 400 ml) of hot water at 85 ° C., and water was removed to produce an industrial fat or oil having free fatty acids removed.

Comparative Example 2: Prior Art (① Magnesium Silicate Adsorption)

After adding 1.0 wt% (20 g) of magnesium silicate powder as an adsorbent to 2,000 g of waste cooking oil containing high content free fatty acid as an adsorbent, it was mixed with a stirrer and reacted at 85 ° C. to produce industrial fats and oils free of fatty acids.

Experimental Example 1: Confirmation of free fatty acid and water removal rate

Free fatty acids and water removal rates according to Examples 1 to 5 and Comparative Examples 1 to 2 are shown in Table 1 below.

Free fatty acid and water removal rate

Waste Cooking Oil Free fatty acid removal result Free fatty acid (%) moisture
(%) Free fatty acid (%) moisture(%) 0.5%
adding 1.0%
adding 2.0%
adding 0.5%
adding 1.0%
adding 2.0%
adding Example 1
(Dry ○, magnesium silicate) 2.3 0.6 0.3 0.2 0.1 0.1 0.05 0.04 Example 2
(Drying X, magnesium silicate) 2.3 0.6 0.5 0.4 0.3 0.2 0.06 0.05 Example 3
(Dry X, activated clay) 2.3 0.6 0.8 1.2 1.8 0.3 0.06 0.05 Example 4
(Dry X, magnesium aluminum silicate) 2.3 0.6 1.2 0.7 0.7 0.4 0.06 0.05 Example 5
(Dry X, magnesium silicate / activated clay) 2.3 0.6 0.4 0.3 0.2 0.2 0.05 0.04 Comparative Example 1
(Flushing) 2.3 0.6 0.3 0.05 Comparative Example 2
(Sodium hydroxide X, magnesium silicate) 2.3 0.6 1.3 0.05

As can be seen in Table 1, the method of the present invention (Example 1) using the drying step and the magnesium silicate after alkali deoxidation, the embodiment without the drying step (Example 2), conventional washing with magnesium silicate / activated clay mixture It was confirmed that the free fatty acid removal rate was high or comparable to that of the alkali deoxidation method (Comparative Example 1).

Experimental Example 2 Checking the Effect of Free Fatty Acid Removal by Drying Process

In order to confirm the effect of drying prior to the adsorption process on the removal efficiency of free fatty acids in the present invention, neutralizing the waste cooking oil having a high free fatty acid content with sodium hydroxide, removing impurities, and then adsorbing with magnesium silicate powder without one drying step. The adsorption efficiency was tested by removing water after removing almost all of the moisture.

Confirmation of Removal Effect of Free Fatty Acids with or without Drying Process division No additives 1.0% added 2.0% added Free fatty acid (%) moisture(%) Free fatty acid (%) moisture(%) Free fatty acid (%) moisture(%) Drying Process × 3.6 0.8 3.5 0.07 3.3 0.05 Drying Process ○ 3.6 0.1 3.1 0.05 2.8 0.04

As shown in Table 2, it was confirmed that free fatty acid was effectively removed in the case of drying before the adsorption step compared with the case of not drying. This is understood because magnesium silicate used as the adsorbent is more sensitive to moisture than free fatty acids.

Experimental Example 3 Removal of Free Fatty Acid and Confirmation of Pigmentation by Addition of Activated Clay

After adding activated clay, the adsorption process under normal pressure and reduced pressure is shown in Table 3 below.

Result of adding activated clay division Before treatment After 0.5% treatment 1.0% after treatment Free fatty acid (%) Color Free fatty acid (%) Color Free fatty acid (%) Color Atmospheric pressure 3.6 8.1 3.8 7.6 4.0 7.2 Decompression reaction 3.6 8.1 3.6 6.8 3.5 5.7

As shown in Table 3, it was confirmed that the free fatty acid was increased under normal pressure, and the free fatty acid was significantly removed under reduced pressure, and the color was also significantly improved compared to the normal pressure. .

Experimental Example 4: Confirming the effect of removing soap powder according to the type of adsorbent

Soap powder removal effect according to the type of adsorbent is shown in Table 4 below.

Color and soap removal result by adding adsorbent division No additives 1.0% added 2.0% added color
(Red) Soap
(ppm) color
(Red) Soap
(ppm) color
(Red) Soap
(ppm) Example 1 8.1 9,960 7.8 1,846 7.6 861 Example 3 8.1 9,960 6.9 3,153 6.1 1,487 Example 4 8.1 9,960 8.1 8,093 8.7 4,028 Example 5 8.1 9,960 7.2 2.093 6.9 913

As shown in Example 1, the result of adsorption with magnesium silicate was the best soap removal effect, and the result of adsorption with a mixture of magnesium silicate and activated clay showed excellent soap removal effect.

Experimental Example 5 Confirmation of Soap Removal Effect by Adsorption Process

The primary impurities were removed after the sodium hydroxide neutralization reaction, and then the results of adsorption with magnesium silicate without the conventional washing process (Examples 1, 2 and 5) and the results of the conventional washing process (Comparative Example 1) are shown in Table 5 below.

Comparison of flushing and magnesium silicate results division Neutralization Washing
20% added 0.5% added 1.0% added 2.0% added moisture
(%) Soap
(ppm) moisture
(%) Soap
(ppm) moisture
(%) Soap
(ppm) moisture
(%) Soap
(ppm) moisture
(%) Soap
(ppm) Comparative Example 1 0.74 3,130 0.1 360 - - - - - - Example 1 0.74 3,130 - - 0.11 12 0.05 0 0.04 0 Example 2 0.74 3,130 - - 0.14 18 0.07 4 0.06 0 Example 5 0.74 3,130 - - 0.15 25 0.07 5 0.05 0

As shown in Table 5, the residual soap content (3,130 ppm) after removing the first impurity was reduced to 360 ppm in the conventional washing process, while in the present embodiment was almost removed to 12 to 25 ppm when added 0.5%, When added 2.0% it was confirmed that the complete removal.

Through the above experiments, it was confirmed that the deoxidation method of the present invention exhibited an excellent free fatty acid removal effect without a washing step which was an essential step in the prior art.

1 is a process chart of a conventional alkali deoxidation method for removing free fatty acids from waste cooking oil.

2 is a process chart of the alkali deoxidation method according to the present invention.

Claims (6)

In the method for removing free fatty acids from waste cooking oil containing a large amount of free fatty acids by alkali deoxidation method, A neutralization step of neutralizing free fatty acids by mixing sodium hydroxide solution with animal and vegetable waste cooking oil; A primary impurity removal process for removing sodium hydroxide remaining after the reaction, the feet of neutralized fatty acid salts and other impurities by centrifugation or standing; And A secondary impurity removal step of removing the waste adsorbent after adsorbing the impurities by adding and stirring the adsorbent after removing the primary impurities; Free fatty acid removal method of animal and vegetable waste cooking oil comprising a. The method of claim 1, further comprising a drying step of removing water remaining after the primary impurity removal step to increase the adsorption reaction efficiency before adsorbent addition. The method of claim 1 or 2, wherein the adsorbent is one or a mixture thereof selected from the group consisting of magnesium silicate, activated clay, aluminum silicate, activated carbon, and diatomaceous earth. . The method of claim 3, wherein the content of magnesium silicate as an adsorbent is 0.2% to 3.0% by weight based on the weight of the waste cooking oil. The method of claim 3, wherein the content of activated clay, which is an adsorbent, is 0.2% to 3.0% by weight based on the weight of the waste cooking oil, and the adsorption is carried out under reduced pressure. The method of claim 3, wherein the adsorbent mixture of magnesium silicate and activated clay is 0.7% to 3.0% by weight based on the weight of waste cooking oil.

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