JP2001354993A - Process for recycling edible oil waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recycle free fatty acids contained in used edible oil wastes by reducing the acid value without emulsifying a large amount of water. SOLUTION: In the process for recycling edible oil wastes, an aqueous solution containing at least one selected from the group consisting of NaOH, K2CO3, NaCl, Na2SO4, KOH, Na2CO3, Na3PO4 and Na2HPO4 is blended to a used oil with an increased acid value at a concentration within the range close to its solubility in the oil. Then, the mixture is allowed to undergo reaction at <=70 deg.C to separate and remove the precipitating reaction product of tree fatty acids.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for regenerating waste oil having an increased acid value after use by treating free fatty acids with an acid value to reduce the acid value and regenerating the waste oil.

[0002]

2. Description of the Related Art Conventionally, an oil obtained by cooking tempura and various fried foods has an acid value that rises to a reference value, for example, 2.0 or more. However, its disposal is costly and causes environmental pollution.

[0003] The cause of the increase in the acid value is that fats and oils containing triglycerides as a main component are hydrolyzed by moisture from fried foods at high temperatures during cooking to produce free fatty acids. The removal allows the acid value to be reduced.

On the other hand, it is known that the free fatty acid is reacted with NaOH or the like to separate the free fatty acid in the form of a saponified product. However, this method is difficult to dissolve due to the difference between water and oil. A method based on emulsification using a method such as the above is generally used. For example, according to Japanese Patent Application Laid-Open No. 7-18289, a food waste oil and an alkali hydroxide solution are mixed to form an emulsion, a saturated saline solution is added to the emulsion, the mixture is heated while stirring, and the emulsion is boiled. The aqueous solution is separated from the oil and the aqueous solution, and the aqueous solution is mixed with hydrochloric acid to separate it into a weakly acidic solution.The weakly acidic solution is mixed with an aqueous alkali hydroxide solution to make it weakly alkaline. It is intended to separate into an alkaline liquid.

However, according to the above-mentioned method of emulsification, (1) once emulsified with a large amount of water, it is difficult to separate and remove it again, for example, as described in JP-A-7-18289. Then, 26 liters of sodium hydroxide aqueous solution was added to 130 liters of waste oil to emulsify, and further, 52 liters of saturated saline solution was added, and the mixture was heated and stirred and allowed to stand for 48 hours. It is described that an edible oil layer is separated therebelow, a soap layer containing a large amount of impurities below the edible oil layer, and an aqueous solution layer of sodium hydroxide and salt in which the impurities are dissolved is separated at the lowermost layer. This is not suitable for practical use of a waste oil reclaiming apparatus in restaurants, canteens, food factories, etc., which require simple and quick processing. (2) In order to promote the reaction between the emulsified fatty acid and the saline solution, it is necessary to boil the mixture at 90 ° C. or higher. However, as a result, the oil is easily hydrolyzed and free fatty acids are easily produced. There is a risk of becoming.

[0006]

Therefore, as a result of repeated studies, the present inventors have found that the concentration of free fatty acids contained in edible waste oil after use is low as an absolute amount, and that the oil and water are highly insoluble. In view of the two facts that a certain amount of dissolving power is present, the inventors have found that the acid value can be reduced without emulsifying a large amount of water, thereby completing the present invention.

[0007]

[Means for Solving the Problems]

The object of the present invention is edible waste oil whose acid value has increased due to the use of tempura oil, various frying oils, and the like. Among them, it is mainly used in restaurants, canteens, food production factories and the like. The aim is to develop a method and apparatus suitable for rapid processing with a relatively small apparatus. Although the used oil forms triglycerides as fats and oils, the fatty acid is released by heating, oxidation, hydrolysis and the like accompanying use, and the acid value is increased.

Therefore, conventionally, sodium hydroxide or the like is allowed to act on the above fatty acid, and the fatty acid is reacted in the form of an emulsion.
As described above, there is an attempt to treat as a sodium salt, but it is troublesome such that separation is troublesome. Therefore, the present inventors have found that (1) the concentration (wt%) of free fatty acids contained in edible waste oil after use is about half of the acid value and is small in absolute amount, and (2) it does not mix. We focused on two facts that even oil and water, which are representative of those, have the ability to dissolve water in the oil in a certain concentration range.

[0010] First, the amount of free fatty acids in edible waste oil was examined, and the following results were obtained.

[Table 1] Crude oil: Spent edible oil generated in the deep-fried food processing plant. The crude oil has an acid value of 1.7 (mg / g) and its free fatty acid content (wt%) is about half the acid value. As a result, it was found that even if it was a free fatty acid that raised the acid value, the amount was relatively small when judged from its absolute amount.

Next, the water content of the actual waste oil was tested, and the literature on the solubility of water in general oil was examined. The results are as shown in the table below.

[Table 2] Crude oil 1: Used edible oil similar to Table 1 Crude oil 2: Same as above Measurement method: Karl Fischer method

[Table 3] The actual ratio of water dissolution to waste oil is 0.13%, which is about 0.1-0.3% in the literature,
It was confirmed that the oil had a power of dissolving water at a value near this value.

Considering based on the above results, the oil
By mixing an aqueous solution containing aOH or the like in a concentration range near the solubility of water, the inventors came to think that NaOH or the like would react with free fatty acids without emulsification. Therefore, the following experiment was performed. First, crude oil (same as in Table 1) was heated to about 60 ° C.
A processing chemical such as OH was added, and the mixture was stirred at about 60 ° C. for 15 minutes, and then filtered to obtain a processed oil. The acid value decrease of the treated oil was measured to examine the effect of adding a metal salt solution.

[Table 4] As a result, it was found that the addition of a small amount of the metal salt can greatly reduce the acid value.

Next, the removal rate of the crude oil was measured by measuring the actual content of free fatty acids irrespective of the acid value. Test conditions: Crude oil (the same as in Table 1) was heated to about 60 ° C., and a treatment chemical of 25 wt% NaOH was added thereto at 6 ml /
After stirring at about 60 ° C. for 15 minutes, the mixture was filtered to obtain a treated oil. The results were as shown in Table 5.

[Table 5] The acid value of this crude oil was 1.7 (mg / g), the acid value after treatment was 0.5 (mg / g), and the acid value reduction rate was 71%.
Met. As a result, about 68% of the free fatty acids of the crude oil were removed by the addition of the metal salt, and a strong correlation with the acid value reduction rate was observed.

Further, instead of the above reagents, the relationship between the addition of a NaOH solution and the decrease in the acid value thereof by an electrolytic treatment apparatus capable of safely supplying a solution described below was measured. Conditions: Crude oil (same as in Table 1) was heated to 60 ° C., and an electrolytic treatment solution containing NaOH described below was added at each concentration, and the crude oil was heated to about 60 ° C.
Stirred at 15 ° C. for 15 minutes and filtered with filter paper to obtain a treated oil, and its acid value was measured. The results were as shown in Table 6 and FIG.

[Table 6] Electrolysis treatment solution: A solution containing a 4 wt% NaOH solution. As a result, a decrease in the acid value was also confirmed by the addition of the electrolytic treatment solution. However, the addition amount of the electrolytic treatment solution was 16.7 ml / l.
(1.8 wt%), emulsification starts around 2 wt.
At 0 ml / l (2.2 wt%), the intensity became even more intense, about 1
0ml / l (0.10wt%)-13.6ml / l
(1.5 wt%), the phase was stable and in a good state.

From the above experiments, when the aqueous solution of sodium hydroxide is mixed with the free fatty acid contained in the waste oil within the range of the solubility of water, the water component containing sodium hydroxide is reduced by the law of entropy increase. Within the range of solubility, it spontaneously diffuses into the oil component, and the free fatty acid in the oil component frequently comes into contact with sodium hydroxide in the water component. Is done. When a water component is introduced far beyond the range of solubility, water and oil are clearly separated, and must be obtained by emulsion.

Therefore, it is desirable that the above reaction is induced within the range of solubility. However, even when the solubility exceeds a certain range of solubility in a strict sense, the range in which the above reaction can be promoted is actually achieved. There is. The range was about 0.10 to 1.5 wt% as shown in Table 6 in the case of a 4 wt% NaOH solution.

The compound used in the neutralization reaction is Na
OH, K₂CO₃, NaCl, Na ₂SO₄Others,
KOH, Na showing alkalinity when an aqueous solution is prepared
₂CO₃, Na₃PO₄, Na₂HPO₄Using
These may be used alone or in combination.
No. Also in these cases, the range that leads to the neutralization reaction is
Within the range of the resolution and as in the case of the NaOH solution 0.10 to
It is about 1.5 wt%.

Further, when the reaction temperature was examined at this time, the following facts were found. Test conditions: Crude oil (same as in Table 1) was heated to each temperature,
6 ml / l of a treatment chemical of 25 wt% NaOH was added thereto, and the mixture was stirred for 15 minutes and filtered to obtain a treated oil.

[Table 7] ：: Good filtration state △: Difficult filtration state That is, according to the method, the reaction temperature required for the neutralization reaction may be 70 ° C. or less, which is much more than the method using an emulsion requiring boiling at 90 ° C. or more. It was a good condition.

The stirring is performed in order to promote the reaction.

As the reaction proceeds, large ones of the reaction products precipitate and small ones float, and precipitates of sodium hydroxide are formed. These are filtered and separated by filter paper or the like. I do.

Thus, NaOH, K ₂ CO ₃ , NaCl, Na ₂ S are used for the used oil having an increased acid value.
O ₄ , KOH, Na ₂ CO ₃ , Na ₃ PO ₄ , Na ₂
An aqueous solution containing at least one of the group consisting of HPO ₄ is mixed in a concentration within a range close to the solubility of water in oil and reacted at a temperature of 70 ° C. or less to separate and remove the reaction precipitate of free fatty acids. The present invention provides a method for regenerating and processing edible waste oil according to the present invention.

FIG. 2 shows an example of an apparatus for executing the above-mentioned regenerating treatment method.
And a heater 5 is disposed at the bottom of the processing tank 2 for injecting a NaOH solution or the like to adjust the temperature and to provide a stirrer 4.
To promote the reaction, and after the reaction, the mixture is filtered by the filter 6 outside the tank.

Next, an electrolytic treatment apparatus for selecting and using NaOH among the compounds used for the neutralization reaction will be described. In other words, the above-mentioned method using a treatment chemical solution is simple as a method, but involves danger since alkali is directly used. Therefore, regardless of the treatment liquid, N
A means for obtaining an aOH solution was considered. As shown in FIG. 3, the electrolytic treatment apparatus used in the present invention includes a dimensionally stable electrode disposed on the anode, an electrode such as SUS disposed on the cathode, and a cation exchange membrane interposed between the two electrodes. The anode side is filled with a saturated saline solution, and the cathode side is filled with pure water.

The dimensionally stable electrode used for the anode refers to an electrode capable of avoiding elution during electrolysis, and refers to a titanium electrode coated with a platinum group composite oxide such as ruthenium oxide or iridium oxide. On the cathode side,
A commonly used SUS is used.

A cation exchange membrane is provided between the anode and the cathode to divide the cell, and the cation exchange membrane allows only Na ⁺ ions to selectively move to the cathode side, and generates cations on the cathode side. the OH ^- is because that fasten to the cathode side of the ion.

The operation of the above electrolyzer will be described first.
On the anode side, NaCl → Na ⁺ + Cl ⁻ , 2Cl ⁻ +
The reaction of 2e → Cl ₂ proceeds. At this time, according to the titanium electrode coated with the platinum group composite oxide used for the anode, the internal electrode metal does not elute.

Next, on the cathode side, H ₂ O → H ⁺ + OH
⁻ , 2H ⁺ + 2e → H ₂ proceeds, and OH ⁻ ions are electrolytically generated and hydrogen is generated.

The Na ⁺ ions of the anode pass through the cation exchange membrane and move to the cathode side, where water combines with OH ⁻ ions generated by electrolysis to generate NaOH. At this time, the OH ⁻ ions generated on the cathode side do not move to the anode side due to the function of the cation exchange membrane, and are intensively combined with the Na ⁺ ions passing through the cation exchange membrane,
There is no concern about binding to other ions.

Although the method for producing a NaOH solution by electrolysis has been described above, KOH is also used as a method for electrolysis.
The formation of a solution can be promoted, in which case it can be treated exactly like a NaOH solution, except that the anode side is filled with a saturated potassium chloride solution.

Accordingly, NaOH by the above electrolytic treatment apparatus
When the combination of the generation means and the waste oil regeneration method is combined, a dimensionally stable electrode is disposed on the anode, an electrode such as SUS is disposed on the cathode, a cation exchange membrane is interposed between the two electrodes, and a positive electrode is disposed on the anode side. An NaOH aqueous solution or a KOH aqueous solution is generated by an electrolytic device filled with a saturated saline solution or a saturated potassium chloride solution and the pure water on the cathode side.
The aqueous solution is mixed with the used oil having an increased acid value at a concentration within a range close to the solubility of the water in the oil.
A method for regenerating edible waste oil, characterized in that the reaction is carried out at a temperature of not more than ℃ and the reaction precipitate of free fatty acid is separated and removed.

As described above, such a processing method uses NaCl
Or KCl as a raw material, and it is safe.
Since the productivity of H or KOH is excellent, a high concentration of alkali can be obtained simply.

[0032]

Example 1 200 liters of used edible oil produced in the deep-fried food processing factory was sampled and injected into a treatment tank. 6 ml / l of a 25 wt% NaOH solution was added thereto, and about 1
Stir for 5 minutes and filter it through a filter. As a result, the acid value of the used edible oil, which was initially 1.7, was reduced to 0.5, reaching a reduction rate of 71%, and a sufficiently reusable oil was obtained.

[0033]

Example 2 A platinum group composite oxide coated titanium electrode was provided on the anode, a SUS electrode was provided on the cathode, and a saturated saline solution was provided on the cathode side in a tank provided with a cation exchange membrane in the middle. Was filled with ion-exchanged water to form an electrolytic cell. About 600
A / m ² current is applied for about 2 hours, and 4 wt% N
An aOH solution was prepared. Next, 200 liters of the same used cooking oil as in Example 1 were collected and injected into the treatment tank. To this was added 13.6 ml / l of a 4 wt% NaOH solution prepared in the electrolytic cell, and the mixture was stirred for about 15 minutes with a stirrer while maintaining the temperature at 60 ° C. with a heating heater, and filtered with a filter. As a result, the acid value of the used edible oil, which was initially 2.8, was reduced to 1.8, reaching a reduction rate of 36%, and a sufficiently reusable oil was obtained.

[0034]

The present invention has the following excellent effects based on the above configuration and operation. (1) Since a free fatty acid which is originally a small amount is treated by using the action of solubility, separation of the reaction product is easy, troublesome separation that occurs when treated with an emulsion is eliminated, and simple and quick. Processing becomes possible, and it becomes an optimal processing means in restaurants, canteens, food manufacturing factories, and the like. (2) Further, in combination with a method of producing a NaOH solution or a KOH solution by an electrolytic treatment device using a cation exchange membrane or the like, a high-concentration NaOH solution can be obtained simply,
A simple and quick means for regenerating waste oil can be obtained consistently, and safe operation can be performed by using safe NaCl or KCl as a raw material without directly using dangerous alkali.

[Brief description of the drawings]

FIG. 1 is a graph showing an acid value decrease by the method of the present invention.

FIG. 2 is a reproduction processing apparatus.

FIG. 3 is an electrolytic processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Regeneration apparatus 2 Processing tank 3 Oil feed pump 4 Stirrer 5 Heating heater 6 Filtration machine

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4B026 DC06 DL01 DP01 DP10 4H059 AA03 AA04 AA07 AA09 AA10 BC03 BC13 CA31 CA32 CA75 CA93 EA21

Claims (3)

[Claims] (1) NaOH is used for a used oil having an increased acid value.
OH, K ₂ CO ₃ , NaCl, Na ₂ SO ₄ , KO
An aqueous solution containing at least one of the group consisting of H, Na ₂ CO ₃ , Na ₃ PO ₄ , and Na ₂ HPO ₄ at a concentration close to the solubility of water in oil;
A method for regenerating edible waste oil, comprising reacting at a temperature of 0 ° C. or lower to separate and remove a reaction precipitate of free fatty acid. 2. A dimensionally stable electrode is provided on the anode, and S is provided on the cathode.
An electrode of US or the like is provided, a cation exchange membrane is interposed between the two electrodes, and the anode side is filled with a saturated saline solution or saturated potassium chloride, and the cathode side is filled with pure water.
An aOH aqueous solution or a KOH aqueous solution is generated, and the NaOH aqueous solution or the KOH aqueous solution is mixed with the used oil having an increased acid value in a concentration close to the solubility of water in the oil, and the temperature is 70 ° C. or less. And react with
A method for regenerating edible waste oil, comprising separating and removing a reaction precipitate of free fatty acids. 3. The range close to the solubility is 0.1 to 1.5 watts.
The method for regenerating edible waste oil according to any one of claims 1 and 2, wherein the percentage is t%.