PT84865B - PROCESS OF TREATMENT OF GLYCERIDATED OLEOS REFINED BY CAUSTIC TREATMENT FOR THE REMOVAL OF SAVERS AND PHOSPHOLIPIDS - Google Patents

Abstract

Adsorbents comprising amorphous silicas with effective average pore diameters of about 60 to about 5000 Angstroms are useful in processes for the removal of soaps and phospholipids (along with associated metal ions) from caustic treated or caustic refined glyceride oils.

Description

Background of the present invention relates to a method for refining glyceride oils by contacting the oils with an adsorbent capable of removing certain impurities. More specifically, it has been found that amorphous silicas are quite effective in adsorbing either soaps or phospholipids, caustically treated or caustically refined glyceride oils, in order to produce oily products with substantially reduced concentrations of these impurities. For the purposes of this description, the term impurities refers to soaps and phospholipids. Phospholipids are associated with metal ions and together with them will be referred to here as trace contaminants. The term glyceride oil as used herein is intended to encompass both vegetable and animal oils. The term is primarily intended to describe so-called edible oils, ie, oils derived from fruits or plant seeds that are used primarily in food products, but it should be understood that oils whose end use is not like edible oils are also included in the designation. The present invention is applicable to oils that have been subjected to caustic treatment, which is the refining step in which soaps are formed in the oil.

Crude glyceride oils, particularly vegetable oils, are refined by a multi-step process, the first step of which is typically degumming or sloughing, treatment by water or a chemical such as phosphoric acid, citric acid or acetic anhydride . This treatment removes some but not all gums and some other contaminants. Some of the phosphorus content of the oil is removed with the gums. Both crude and degummed oil can be treated in a chemical or caustic refining process. The addition of an alkaline solution, caustic soda for example, to a crude or degummed oil causes neutralization

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-3tion of free fatty acids forming soaps.

This step in the refining process will be referred to here as caustic treatment and oils treated in this way will be referred to as caustically treated oils. The soaps generated during the caustic treatment are an impurity that must be removed from the oil because they have a detrimental effect on the taste and stability of the finished oil. In addition, the presence of soaps is detrimental to the catalysts used in the oil hydrogenation process.

Current industrial practice is to first remove soaps by centrifugal separation (referred to here as primary centrifugation). In this description, oils that have been subjected to caustic treatment and primary centrifugation will be referred to here as caustically refined oils. Conventionally, the caustically refined oil, which still has a significant soap content, is washed with water, which dissolves the soaps from the oil phase to the aqueous phase. The two phases are separated by centrifugation, although complete separation of the phases is not possible, even under the most favorable conditions. The light phase discharge is oil washed with water that now has a reduced soap content. The heavy phase is a diluted solution of soap in water. Often, the water washing and centrifugation steps have to be repeated in order to reduce the soap content in the oil below 50 ppm. The oil washed with water must then be dried to remove residual moisture below less than 0.1 weight percent. The dry oil can then be transferred to the bleaching process or it can be shipped or stored as refined oil once.

A significant part of the residual discharge current from the caustic refining of vegetable oil results from the water washing process used to remove the soaps. In fact, a primary reason for refiners to use physical refining processes is to avoid production

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-4of a residual current, associated with the removal of soaps, generated in the caustic refining process: since no caustic product is used in physical refining, no soaps are generated. Additionally, in the caustic refining process, some oil is lost in the water washing process. In addition, in the caustic refining process to which the present invention refers, the raw material for the manufacture of soap must be treated before it can be used or discharged, typically with an inorganic acid, such as sulfuric acid, in a process called acidulation. Sulfuric acid is frequently used. It can be seen that the soap removal process consists of a large number of separate unit operations, resulting in each loss of oil. The removal and availability of soaps and aqueous raw material for the manufacture of soaps is one of the most important problems associated with the caustic refining of glyceride oils.

In addition to removing the soaps generated in the caustic refining process, trace contaminants containing phosphorus have to be removed from the oil. The presence of these trace contaminants can lead to the appearance of colors, odo. flavors in the finished oil product. These compounds are phospholipids with which the ionic forms of the metals calcium, magnesium, iron and copper are associated. For the purposes of the present invention, references to the removal or adsorption of phospholipids are also intended to include the removal or adsorption of the associated metal ions. The adsorption of phosphorus in various adsorbents (for example, bleaching soil) has been practiced, although only for oils that are going to undergo physical refining (in which no soap is generated), or caustic refining subsequent to washing steps with water (in which soaps are removed). There has been no adsorption process that has succeeded in removing both soaps and phospholipids at an early stage of refining when large amounts of soaps are present.

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-5Summary of the invention /

And now a simple physical adsorption process is provided, where soaps and phospholipids can be removed from caustically treated vegetable oils or caustically refined in a single unit operation. This unique process completely eliminates the need to subject □ caustically treated or caustically refined oil to a water washing process in order to remove soaps. It also eliminates the need for a separate adsorption process to reduce the oil content in phospholipids. The process described here. crito uses amorphous silica adsorbents with an average pore diameter greater than 60 A, which can remove all or substantially all soaps from the oil and which reduces the oil content in phospholipids to at least less than 15 parts per million, preferably less than 5 parts per million, most preferably virtually zero.

The primary objective of the present invention is to introduce into the caustic refining of glyceride oils a single unitary operation that eliminates the soap and that reduces the oil content in phospholipids to acceptable levels. The adsorption of salts and phospholipids (together with associated contaminants) on amorphous silica as described, offers a tremendous advantage in caustic refining, by eliminating several unit operations when conventional water washing, centrifugation and drying are used for remove soaps from oils. Additionally, this method eliminates the need for wastewater treatment and available materials resulting from those operations. In addition to the cost savings achieved with this tremendous simplification of oil processing, the overall value of the product is increased since the most significant by-product of caustic refining, the raw material for the manufacture of diluted aqueous soap solution, has a very low value and requires substantial treatment before discharge is permitted by environmental authorities.

«ÍBIP '

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-6 It is also intended that the use of the process of the present invention can reduce or potentially eliminate the need for treatment with bleaching soil. In the present invention, only one adsorption step is used for both the removal of soaps and phospholipids. Typically, additional treatment with bleaching soil will not be required to remove these impurities. The reduction or elimination of an additional step with blasting cylinder will result in substantial oil conservation, since this step typically results in significant oil losses. In addition, since the bleaching earth after use tends to spontaneously combust, the reduction or elimination of this process will lead to a professional and environmentally safer process.

An additional objective is to simplify costs. recovery and processing processes hitherto associated with the preparation of the aqueous raw material for the manufacture of soap for use in the animal feed industry. The silica adsorbent after use can be used in animal feed, either as is, or after acidulation to convert the soaps into free fatty acids. The need for drying or concentrating the diluted raw material for the manufacture of soaps in the conventional caustic refining process is eliminated in the process of the present invention.

Description of the figures

Figure 1 is a graphical representation of the adsorption isotherms to determine the capacity of amorphous silica to adsorb phospholipids and combined soaps. Isotherms are based on the results of Example II as shown in Table V.

Figure 2 is a graphical representation of the adsorption isotherms for determining the capacity of silica amorphous to adsorb phospholipids to an oil treated with a V?

IpiF

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-7 flower less than 30 parts per million residual soap. Isotherms are based on the results of Example II, as shown in Table V.

Detailed description of the invention

Amorphous silicas have been found to be particularly well suited for the removal, both of sabffes and of phospholipids, of caustically refined glyceride oils. The process for removing these impurities as described in detail here essentially comprises the steps of selecting a caustically treated or caustically refined glyceride oil comprising soaps and phospholipids, selecting an adsorbent comprising a suitable amorphous silica, contacting the oil treated caustically or refined caustically with the adsorbent, allow the soaps and phospholipids to be adsorbed on the amorphous silica, separating the adsorbent-treated oil from the adsorbent.

By the process of the present invention, soaps and phospholipids can be removed from oils in a single step of addition. dog. Furthermore, it has been verified that the presence of higher levels of soap in the oil to be treated, significantly increases the capacity of amorphous silica to adsorb phosphorus. That is, the presence of soaps at levels below the maximum adsorbent capacity of the silica, makes it possible to substantially reduce the phosphorus content for silica loads lower than those required in the absence of soaps.

The process oils described here can be used to remove phospholipids from any caustically refined glyceride oil, for example, soybean oils, peanuts, rapeseed, corn, sunflower, palm, coconut, olive, cotton, etc. The refining process caustic involves neutralizing the free fatty acid content of crude or degummed oil by treatment with bases, such as sodium hydroxide or sodium carbonate, which are typically used in aqueous solution. 0

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-8 neutralized free fatty acid, present in the form of an alkali or alkaline earth metal salt, is defined as soap. The soap content of the treated oil will caustically vary depending on the free fatty acid content of the unrefined oil. The values presented as typical in the industry, vary between about 300 ppm, for the caustically treated oil (Erickson, Ed., Handbook of Soy Oil Processing and Utilization * ', Chapter 7, Refining, p. 91 (1980)), and about 10-50 ppm in soap for caustically treated oil and primary centrifuged oil (Christenson, ”Short Course, Processing and Quality Control of Fats and Oils, Fig. 1, presented at Amer. Oil Chemists' Soc. (May, 5 -7, 1983)). Completely refined oils should have a soap content close to zero. Conventional separation and water washing processes remove about 90% of the soap content generated in the caustic treatment step. The process presented here will reduce the soaps to levels acceptable to the industry, that is, to values below about 10 ppm, preferably below about 5 ppm, most preferably to about zero ppm, without using washing steps with Water.

The removal of vertigious contaminants (phospholipids and associated metal ions) from edible oils is also an important step in the oil refining process, since they can give the finished oil colors, odors and flavors. Typically, the acceptable concentration of phosphorus in the finished oil product should be less than about 15.0 ppm, preferably less than about 5.0 ppm, in accordance with current industry practice. As an illustration of the goals of refining in relation to trace contaminants, typical levels of phosphorus in soybean oil are shown in Table I, in various states of chemical refining.

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In addition to removing phospholipids, the process of the present invention also removes ionic forms of the metals calcium, magnesium, iron and copper from cooking oils, which are believed to be chemically associated with phospholipids, and which are removed together with phospholipids. These metal ions themselves have a detrimental effect on refined oil products. Calcium and magnesium ions can result in the formation of precipitates, particularly with free fatty acids, resulting in unwanted soaps in the finished oil. The presence of iron and copper ions promotes oxidative instability. In addition, each of these metallic ions is associated with catalyst poisoning when the refined oil is catalytically hydrogenated. Typical concentrations of these metals in soy oil in various states of chemical refining are shown in Table I. Throughout the description of the present invention, unless otherwise indicated, the reference to removal of phospholipids is also intended to include the removal of ions associated metals.

adsorption process - The amorphous silicas described below exhibit a very high capacity for the adsorption of soaps and phospholipids. The ability of silica to adsorb phospholipids is improved by the presence of higher soap contents in the starting oil, provided that sufficient silica is used to obtain the oil treated with adsorbent with soap levels of approximately 30 ppm or less. When the residual levels in soap (in the oil treated with adsorbent) are about 30 ppm, there is an increased silica capacity for phospholipid adsorption. The total available adsorption capacity of amorphous silica is believed to be about 50 to 75% by weight on a dry basis.

The silica charge should be adjusted so that the total soap and phospholipid content does not exceed about 50 to 70% by weight of the added silica, on a dry basis. And es. that the maximum adsorption capacity observed in a particular application is a function of the specific properties

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-strips of the silica used, the type of oil and the state of refining, and processing conditions, such as temperature, degree of mixing and silica-ile contact time. Cal. glasses for a specific application can be made by an individual of ordinary ability, provided that you follow this description.

The adsorption step is itself carried out by conventional processes in which the amorphous silica and the ileum are brought into contact, preferably in a way that facilitates the adsorption. The adsorption step can be carried out by any convenient batch or continuous process. In any case, stirring or any other mixing process will increase the adsorption efficiency of the silica.

The adsorption can be carried out at any temperature convenient for the oil to be liquid. The caustically refined oil and the amorphous silica are brought into contact, as previously described, for a sufficient period of time. achieve the desired levels of soap and phospholipid in the treated oil. The specific contact time will vary slightly with the selected process, i.e., batch or continuous. In addition, the adsorbent charge, that is, the relative amount of adsorbent that is brought into contact with the oil, will affect the amount of soaps and phospholipids removed. The adsorbent charge is quantified as the percentage by weight of amorphous silica (on a dry basis after ignition at 9549C (17509F)), calculated based on the weight of processed oil. The preferred adsorbent charge is at least about 0.01 to about 1.0% by weight, dry base, most preferably at least about 0.1 to about 0.15% by weight, dry base .

As can be seen in the Examples, a significant reduction in the content of soap and phospholipid is achieved by the process of the present invention. The soap content and the phosphorus content of the treated oil will depend mainly on the oil itself, as well as on the silica, filler, process, etc. For example, with reference to Table I, it will be noted that the soap content ini. will vary significantly depending on whether the oil is

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-12 treated by this adsorption process, after caustic treatment or after primary centrifugation. Similarly, the phosphorus content will be slightly reduced after degumming, caustic treatment, and / or primary centrifugation. However, phosphorus levels below 15 ppm, preferably below 5.0 ppm and most preferably below 1.0 ppm, and soap levels below 50 ppm, preferably below about 10 ppm, can be achieved by this adsorption method. and most preferably from substantially zero ppm.

After adsorption, the silica enriched in soap and phospholipid is removed from the oil treated with adsorbent by any processes deemed convenient, for example, by filtration or centrifugation. The oil can be subjected to additional finishing processes, such as steam refining, bleaching and / or deodorizing * For low levels of faith. heat and soap, it may be feasible to use heat bleaching instead of a bleached earth pass, which is associated with significant oil losses. Even when bleaching earth operations are to be used, simultaneous or sequential treatment with amorphous silica and bleaching earth is an extremely efficient global process. By first using the process of the present invention to decrease the soap and phospholipid content, and then treating with bleaching soil, the effectiveness of this last step is increased. Thus, the amount of bleaching earth required can be significantly reduced and the bleaching earth will operate more effectively per unit mass. The silica after use can be used in animal feed, either as is, or after acidulation to convert soaps into fatty acids. Alternatively, it may be feasible to elute the adsorbed impurities from the silica already used in order to recycle the silica for another oil treatment.

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-130 Adsorptive term amorphous silica as used herein, in order to encompass silica gels, precipitated silicas, dialytic silicas and smoked silicas in their various prepared or activated forms. Both silica gels and precipitated silicas are prepared by destabilizing aqueous silicate solutions by neutralization with acid. In the preparation of silica gel a silica hydrogel is formed which is then typically washed to lower the salt content. The washed hydrogel can be ground, or it can be dried to the extent that its structure no longer changes as a result of the contraction. The dry and stable silica is called xero gel. In the preparation of precipitated silicas, destabilization is carried out in the presence of polymerization inhibitors, such as inorganic salts, which cause the hydrated silica to precipitate. The precipitate is typically filtered, washed and dried. For the preparation of the gels or precipitates useful in the present invention, it is preferred to initially dry the gel or precipitate until the desired water content is obtained. Alternatively, they can be dried and water can then be added until the desired water content is reached, prior to use. Dialytic silica is prepared by precipitating silica from a soluble silicate solution containing electrolyte salts (eg, NaNO-j, Na ₂ SO4, ΚΝΟ ^) by electrodialysis, as described in the US patent application, pen tooth, nS, series 533206 (Winyall), Particulate Dialytic Silica, deposited on September 20, 1983. Smoked silicas (or pyrogenic silicas) are prepared from silica tetrachloride by high temperature hydrolysis or by other convenient processes, It is not expected that the specific preparation process used to prepare amorphous silica will affect its usefulness in this process.

In the preferred embodiment of the present invention, the silica adsorbent will have the largest possible surface area, in pores that are large enough to allow □

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-14 access to soap and phospholipid molecules, while being able to maintain good structural integrity in contact with oil. The structural integrity requirement is particularly important when silica absorbers are used in continuous flow systems that are susceptible to fragmentation and clogging. Amorphous silicas suitable for use in this process have surface areas of up to about 1200 square meters per gram, preferably between 100 and 1200 square meters per gram. It is also preferred that the surface area is as much as possible contained in pores with diameters greater than 60 A.

The process of the present invention uses amorphous silicas with substantial porosity contained in pores with diameters greater than about 60 A, as defined herein, after appropriate activation. Typically activation is achieved by heating to temperatures of about 2323 ° C to 371 ° C (450 to 700 ° F) under vacuum. A convention that describes silicas is that of the average pore diameter (DMP), typically defined as the pore diameter for which 50% of the surface area or porous volume is contained in pores with diameters larger than the said DMP and 50% of the pore size. surface area or porous volume is contained in pores with diameters smaller than the said DMP. Thus, in amorphous silicas suitable for use in the process of the present invention, at least 50% of the porous volume will be contained in pores of at least 60 A in diameter. Silicas with a higher proportion of pores with diameters greater than 60 A will be preferred, since they will contain a greater number of potential adsorption centers. The practical upper limit for DMP is around 5000 A.

Silicas that have intraparticulate DMP's measured in said range will be suitable for use in this process. Alternatively, the required porosity can be achieved by creating an artificial pore network of inter-particle voids, in the range of 60 to 5000 A. For example, non-porous silicas (i.e., smoked silicas) can be used as aggregate particles. Silicas with or without the pore,

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-15sity required can be used under conditions that create. artificial pore network. Thus, the criterion for selection. amorphous silicas suitable for use in this process is the presence of an average effective pore diameter greater than 60A. silica particles.

DMP value (in Angstroms) can be measured by several methods, or it can be calculated approximately by the following equation that assumes a cylindrical pore model:

(1) DMP (A) = 40,000 x PV (cm ⁵ / g)

AS (m ² / g) where VP is the porous volume (measured in cubic centimeters per gram) and AS is the surface area (measured in square meters per gram).

Both nitrogen porosimetry and mercury porosimetry can be used to measure porous volume in xerogel gels, precipitated silicas and dialytic silicas. The porous volume can be measured by the Brunauer-Emmett-Teller (B-E-T) method with nitrogen described by Brunauer et al., In 3. Am. Chem. Soc., Vol 60, p. 309 (1938). This method depends on the condensation of nitrogen in the pores of the activated silica, and is useful for measuring pores with diameters up to about 600 A. If the sample contains pores with diameters greater than about 600 A, the pore size distribution , at least of the larger pores, is determined by mercury porosimetry, as described by Ritter et al., Ind. Eng. Chem. Anal. Ed. 17,787 (1945). This method is based on determining the pressure required to force mercury into the sample pores. Mercury porosimetry, which is useful for pores of about 30 to about 10,000 A, can be used alone for the measurement of pore volumes in silicas with pores in diameters, both greater than and less than 600 A. Al-

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-16 Alternatively, nitrogen porosimetry can be used in conjunction with mercury porosimetry for these silicas. For the measurement of DMP less than 600 A, it may be desired to compare the results obtained by the two processes. The calculated UP value is used in Equation (1).

For the determination of the porous volume of hydrogels, a different procedure is used that assumes a direct relationship between the porous volume and the water content. A sample of the hydrogel is weighed in a container, and all the water is removed from the amorphous by vacuum at low temperatures (i.e. at room temperature). The sample is then heated to about 232 ° C to 37 ° C (450 to 700 ° F) to activate. After activation, the sample is weighed again to determine the weight of the silica on a dry basis, and the porous volume is calculated using the equation:

(2) PV (cmVg) = TV%

100 - TV $ where TV is the total volatiles determined by the difference between wet weight and dry weight. An alternative method for calculating TV is to measure weight loss by ignition at 954 ° C (see Equation (9) in Example II). The PV value calculated in this way is then used in Equation (1).

The measurement of the surface area in the DMP equation is measured by the process of the B-E-T surface area with nitrogen, described in the article by Brunauer et al., Supra. The surface area of all types of properly activated amorphous silicas can be measured by this method. The measured AS is used in Equation (1) with □ PV measured to calculate the DMP of silica.

It is not believed that the purity of the amorphous silica used in the present invention is critical in terms of the adsorption of soaps and phospholipids. However, when finished products are to have a degree of purity to be used in food products, care must be taken to ensure that the silica used does not contain impure

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-17 leachable quantities that may compromise the desired purity of the product (s). It is therefore preferred to use a substantially pure amorphous silica, although minor amounts, ie, less than about 10%, of other inorganic constituents may be present. For example, suitable silicas may comprise iron in the form of Fe ₂ 0g, aluminum in the form of AlgO 4, titanium in the form of TiO ₂ , calcium in the form of CaO, sodium in the form of Na ₂ 0, zirconium in the form of ZrO ₂ , and / or trace elements.

The following examples are presented for illustrative purposes and are not intended to limit the invention described herein. The following abbreviations have been used throughout the description of the invention:

A - Angstrom (s)

DMP - average pore diameter

B-E-T - Brunauer-Emmett-Teller

C - capacity

Ca - calcium cm ⁵ - cubic centimeter cm - centimeter

Cu - copper

5C - degrees centigrade

b.s. - dry base

9F - degrees Fahrenheit

Fe - iron g - gram

PIA - inductively coupled plasma m - meter

Mg - magnesium min - minutes ml - milliliter

P - phosphorus

PL - phospholipids ppm - parts per million (by weight)

PV - porous volume

—18—

σ / / 0 percentage HR relative humidity rpm rotations per minute s soaps AT surface area s seconds TV total volatiles P Weight

EXAMPLE I (Oil samples on amorphous silica)

Table II shows the properties of the amorphous silica used in these examples.

TABLE II

Sample Area Volume Average diameter Total of of silica superficial ^ 2 porous pore hate ³ volatile ^ 5 Hydrogel 911 1.8 80 64.5

- Surface area (AS) B-E-T, measured as previously described.

- Porous volume (PV), measured as previously described using the hydrogel method.

- Average pore diameter (DMP) calculated as previously described.

- Total volatiles, in percentage by weight (% by weight) by ignition at 954SC.

5-0 hydrogel was obtained from the Davison Chemical Division of W. R. Grace & Co.

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-19The oil samples used in the following examples were prepared by combining oil A (see Table III), a caustically refined soybean oil, collected after caustic treatment and primary centrifugation, but before washing with water and either with sample E or with the E 'oil sample of degummed soybean oils prepared as described below, and not subjected to caustic treatment. The oil sample E 'was prepared in the same way as the oil sample E in Table III, for which the analytical results are presented; Insufficient amounts of E 'im oil sample allow for separate analysis, but it is assumed that the similarly degummed oils were substantially identical. Oil sample A contained large amounts of soaps (362 ppm) determined by measuring the alkalinity expressed as sodium oleate (p.p.m.) by A.O.C.S. Recommended Praç. Cc 17-79 ”. The acid-degummed oils, having not been in contact with caustic products, did not contain soap, but contained significant levels of phosphorus, as indicated by the values for the oil sample E which contained 22.0 ppm phosphorus, measured by spectroscopy of inductively coupled plasma (PIA) emission.

Oil sample A was mixed in various proportions (as shown in Table III), with oil samples E or E ', to prepare oil samples 8, C and D, which are relatively constant in phosphorus and metal ions but with significantly different soap levels. Oil sample B contained 75% of oil sample A and 25% of oil sample E. Oil sample C contained 50% of oil sample A and 50% of oil sample Ε ·. The oil sample D contained 25% of the oil sample A and 75% of the sample. oil '. Each oil sample was analyzed as previously described, to determine trace contaminants (P, Ca, Mg, Fe and Cu) and to determine the soaps. The results are shown in Table III.

The acid-degumming oils (oil samples E and E ') were prepared by heating 500.0 g of oil covered with a fo

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-20 stripped metal covered with nitrogen, in a 409C water bath. 500 ppm of fos acid was then added to the oil. 85% sputum (0.25 g) and the mixture was stirred for twenty minutes while maintaining the nitrogen blanket. Ten milliliters of deionized water were then added and the mixture was then stirred for one hour. The sample was then centrifuged at 2300 rpm for thirty minutes. The upper phase was the degummed oil used in the experiment (the lower phase comprising the gums was discharged).

TABLE III

Sample Vestigial contaminants Soap 3 ppm in oil P Here Mg r 2 Faith Cu ² THE 13.4 0.93 1.03 0.02 0.02 362.0 B 19.4 2.08 1.92 0.00 0.02 180.0 Ç 20.8 3.04 2.46 0.06 0.01 70.0 D 23.7 3.84 3.01 0.07 0.02 30.0 AND 22.9 4.27 3.17 0.11 0.03 0.0 AND" X X X X X X 1 - • Content in contaminants vestigial (P, Ca, Mg, Fe, Ass) were measured in parts per million by spectroscopy of

issuance of PIA.

- The Fe and Cu values presented were very close to the detection limits of this analytical technique.

3-0 soap was determined by A.O.C.S. Recommended Practice Cc 17-79.

x - The E 'oil sample was prepared from the same crude oil as the E oil sample, and by the same acid degumming process. Insufficient quantities of the oil sample E 'were available for analysis, but pres. it is assumed that the values are comparable to those of the oil sample E.

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-21EXAMPLE II (Treatment of oil samples with silica)

The oil samples prepared in Example I were treated with the amorphous silica described in Example I. For each test, 100.0 g of the oil sample (A, B, C, D or E) was heated to 100 ° C, and the silica was added in the amount indicated in Table IV. The mixture was maintained at 100 ° C, while being vigorously stirred, for half an hour. The silica was separated from the oil by filtration. The treated and filtered oil samples were analyzed to determine the levels of soap and trace contaminants by the methods described in Example I. The results presented in Table IV indicate that:

1. The amorphous silica adsorbent removed soaps and trace contaminants (phospholipids and associated metal ions) from oil samples in a single operation.

2. Soaps appeared to be preferentially adsorbed when compared to trace contaminants. In many cases, no soaps were found in the oil treated with silica, while considerable trace contaminants remained in the oil.

3. The capacity of silica adsorbent to adsorb phosphorus appeared to increase with the soap contents in the oil samples. In the sample of oil A for example (362 ppm of soap), a silica charge of only 0.15% by weight, was necessary to reduce the phosphorus content to a value well below 1.0 ppm, whereas for oil samples C,

D and Γ (respectively 70, 30 and 0 ppm of soap) 0.6% by weight silica fillers were required to reduce phosphorus contents to values below 1.0 ppm. The presence of soaps in the oil thus made it possible to reduce the phosphorus contents to values below 1.0 ppm for a silica charge sufficiently lower than that required in the absence of soaps.

The data obtained in Example II demonstrate that the ability of amorphous silica to remove phospholipid and sa65 607

Ref: No. 01-6826

Soil increases effectively with increasing soap content in the starting oil, until maximum adsorption capacity is obtained. The maximum adsorption capacity of the silica hydrogel used under the conditions of Example II was approximately 55% by weight of soaps plus phospholipids.

The data in Table V were calculated from Table IV in order to obtain values for the adsorption capacity of amorphous silica. The calculations were performed as follows. The capacity of amorphous silica for adsorption of combined soaps and phospholipids (Cg_p ^), expressed as a percentage, can be defined as:

co ry a pe (3) ^C s-PL ⁼ / ~ A ^S (pP ^m ) * A ^PL (ppm) _7 _{χ 1Q} -2

Silica (bs,% by weight) where the change in the concentrations of soaps and phospholpids in the oil (from before until after contact with the silica adsorbent) are defined as:

(4) _Initial (ppm) = S (pp «) - _final s (ppm) (5) A ^PL (ppm) = Λρ (ppm) x 30 (6) Initial ^p (ppm) = P (ppm) - ^p After all (7) Silica (bs,% by weight) = Silica (bs, g) —--------- x 100

Oil (g) where Silica (bs, g) is the weight in grams of silica after ignition at 954% (1750SF).

(8) Silica (bs,% by weight) - Silica (as it is, q) .. 100 - TV zx ^ΤΓ · ¹¹¹

100 (9)

Silica (as it is, q) -Silica (bs, q)

Silica (as it is, g)

The capacity of amorphous silica for the adsorption of phospholipids alone (Cpj_), expressed as a percentage, can be defined as:

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-23 (10) C _PL = PL (ppm) _________ _χ 10 ' ²

Silica (bs,% by weight)

The calculated values for changes in phosphorus (P), phospholipids (PL) and soap (s), phospholipids and soap with binates (S-PL) remaining in the oil, the ability to adsorb soap and combined phospholipids (% ^C S-PL ? 'are shown in table V for each of the oil samples treated, together with the starting values of phosphorus and soap The data in Table V were represented graphically in Figure 1 in the form of adsorption isotherms, the% by weight of the phospholipids and soap adsorbed on silica (As -PL) represented in ordinates, depending on the amount of soap and phospholipids that remained in the oil treated with adsorbent (remaining S-PL) represented in abscissa. determine the correction for the phenomenon typically observed for adsorption with increasing capacity (up to a limit value resulting from saturation), with an increase in the adsorbate that remains in the treated material. This phenomenon is predictable from equilibrium considerations.

The data in Table V were also represented in Figure 2 in the form of adsorption isotherms, with the% w / w of the phospholipids adsorbed on silica (ApL) represented in ordinates according to the amount of phosphorus that remained in the oil treated with adsorbent (P ) represented in abscissa. Figure 2 presents the data for the oil samples treated with adsorbent with <30 ppm residual soaps.

The data in Table U and Figures 1 and 2 show the following:

1. The ability of silica to adsorb phospholipids and soaps tends to increase with increasing soap contents of the starting oil.

2. Increasing the soap content of silica tends to increase the adsorption capacity of silica to phospholipids. when the soap content in the treated oil was significant

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-24 again reduced, for example, in this case, to about 30 ppm in soap, as shown in Table V and Figure 2, for these oil samples and for this adsorbent.

In the previous description the principles, preferred embodiments and modes of operation of the present in wind were described. The present invention, which it is intended to protect here, should not, however, be constructed, being limited to the particular forms presented since these are to be understood as illustrative and not as restrictive. Variations and modifications can be made by those skilled in the art without departing from the spirit of the invention.

Claims (30)

1 - Process for the removal of soaps and phospholipids (together with associated metal ions) from glyceride oils comprising: the selection of a caustically treated or caustically refined glyceride oil comprising soaps and phospholipids; Selecting an adsorbent comprising a suitable amorphous silica; put the di. every oil with said adsorbent; allowing said soaps and phospholipids to be adsorbed on amorphous silica; and separating the oil, treated with adsorbent, from the adsorbent. A process according to claim 1 wherein said glyceride oil is soybean oil. A process according to claim 1 wherein said caustically treated or caustically refined glyceride oil comprises at least about 5 parts per million soaps and at least 1 part per million phosphorus. Process according to claim 3, wherein said causticly treated or refined caustic glyceride oil. it comprises at least 50 parts per million soaps. 65 607 Ref: No. 01- 6826 A process according to claim 3 wherein said caustically treated or caustically refined glyceride oil comprises at least 300 parts per million soaps. A process according to claim 1 which reduces the soap content of the glyceride oil to less than about 50 parts per million. Process according to claim 6, which reduces the soap content of the glyceride oil to less than about 10 parts per million. Process according to claim 7 which reduces the soap content of the glyceride oil to essentially zero parts per million. Process according to claim 1 which reduces the phosphorus content of the glyceride oil to less than about 15 parts per million. Process according to claim 9 which reduces the phosphorus content to less than about 5 parts per million. I A process according to claim 10 which reduces the phosphorus content to less than about 1 part per million. A process according to claim 1 wherein said amorphous silica has an average effective pore diameter greater than 60 Angstroms. A method according to claim 12 wherein said average pore diameter is between about 60 and about 5,000 Angstroms. A process according to claim 12 wherein at least 50% of the pore volume of said silica is included in pores of at least 60 Angstroms in diameter. * 65 607 Ref: No. 01- 6826 A process according to claim 1 wherein said amorphous silica is used in such a way as to create an artificial pore chain of interparticle voids with diameters from about 60 to about 5,000 Angstroms. A process according to claim 15 wherein said amorphous silica is a silica with an average intraparticle pore diameter of less than about 60 Angstroms. A process according to claim 15 wherein said amorphous silica is smoked silica. A process according to claim 1 wherein said amorphous silica is selected from a group consisting of silica gels, precipitated silicas, dialytic silicas and smoked silicas. A process according to claim 16 wherein said silica gel is a hydrogel. A process according to claim 1 wherein said amorphous silica has a surface area of up to about 1,200 square meters per gram. A process according to claim 1 wherein said amorphous silica comprises small amounts of inorganic constituents. 22 - Process for the removal of phospholipids and associated metal ions from glyceride oil by adsorption on amorphous silica, comprising contacting said glyceride oil with said amorphous silica, at a point in the refining process after caustic treatment or caustic refining, such that the said glyceride oil comprises at least 5 parts per million in soaps. Process according to claim 1, wherein said caustically treated or caustically refined oil comprises at least about 50 parts per million sa65 607 Ref: No. 01- 6826 -27bons and said adsorbent-treated oil has a soap content of essentially zero parts per million. A process according to claim 23 wherein said caustically treated or caustically refined oil comprises at least about 30 parts per million soaps and said adsorbent treated oil has a soap content of essentially zero parts per million. A process according to claim 23 wherein said caustically treated or caustically refined oil has been brought into contact with amorphous silica with an amount of silica of at least 0.1 weight percent. A process according to claim 24 wherein said amount of silica is at least 0.15 weight percent. A process according to claim 1 wherein the caustically treated or caustically refined oil comprising at least about 30 parts per million soaps and at least about 5 to 25 parts per million phosphorus is brought into contact with silica amorphous resulting in an adsorbent-treated oil comprising less than about 5 parts per million phosphorus. 28 - Sequential treatment process for the reduction of phospholipid content and for the decolorization of glyceride oils comprising, an initial step of treatment of caustically treated or caustically refined glyceride oil by contact with amorphous silica with an average effective pore diameter of about 60 to 5,000 Angstroms to remove soap almost completely from the oil and to substantially reduce phospholipids, and a subsequent step of treating silica-treated glyceride oil with white earth. 29 - Process for increasing the adsorption capacity of amorphous silica from glyceride oil phospholipids 65 607 Ref: No. 01- 6826 -28 which comprises the contact of said oils with said silica in the presence of at least 5 parts per million soaps. Process according to claim 29 which is conducted in the presence of at least about 30 parts per million soaps.