Preparation method of activated clay

Abstract

This invention provides a method for preparing activated clay, which includes raw material pretreatment and acid activation treatment. The raw material pretreatment includes mixing the raw material with dilute acid to obtain a slurry, ultrasonically treating the slurry until its viscosity is within the range of 20,000-40,000 mPa·s, adding a cation exchange resin, and stirring for a period of time to complete the raw material pretreatment. The activated clay prepared using this method exhibits both improved decolorization rate and significantly increased filtration speed.

Description

Technical Field

[0001] This invention relates to a method for preparing activated clay. Background Technology

[0002] Bentonite is a common clay mineral, mainly composed of montmorillonite. It belongs to the layered aluminosilicate minerals and consists of a tetrahedral silica layer sandwiching two octahedral aluminosilicate layers. This unique layered structure and the resulting negative charge characteristics give it strong water absorption, swelling and adsorption capabilities.

[0003] Activated clay is a product obtained by modifying natural bentonite through physicochemical processes such as acidification and ion exchange. In an acidic environment, the Ca²⁺ between the bentonite layers… 2+ Mg 2+ The isocationic portion is affected by H + Through displacement, activated clay with adsorption capacity and specific surface area far surpasses that of natural bentonite, and can be widely used for clarification and decolorization of edible oils, wines, molasses, and other foods and beverages.

[0004] Currently, the mainstream method for producing activated clay industrially is wet acid activation, which involves directly reacting bentonite slurry with acid using heat. After the reaction, the acidified slurry undergoes solid-liquid separation, rinsing, and drying. This method has advantages such as complete activation and stable product quality. However, traditional activation processes consume large amounts of sulfuric acid (200-500 kg of 98% concentrated sulfuric acid is required to produce 1 ton of activated clay), and the washing process generates a large amount of wastewater (30-80 tons of wastewater are generated for every ton of activated clay produced). For example, when using WZB bentonite as raw material, the amount of sulfuric acid used to obtain activated clay exceeds 25% (Wu Zhansheng, "Research on the Development and Adsorption Performance of High-Efficiency Activated Clay for Decolorizing Edible Oils," Shihezi University, 2006). CN107827119A discloses a two-stage activation process for producing activated clay, which first activates under normal pressure and then under pressure, with the amount of sulfuric acid used reaching 0.4 tons of sulfuric acid per ton of dry ore. Therefore, the existing wet acid activation method has the problem of high acid consumption, which leads to an increase in the amount of water used for subsequent rinsing, which is not conducive to environmental protection and cost control. Summary of the Invention

[0005] The first aspect of the present invention provides a method for preparing activated clay, the method comprising raw material pretreatment and acid activation treatment, wherein the raw material pretreatment comprises mixing the raw material with dilute acid to obtain a slurry, ultrasonically treating the slurry, and after the viscosity of the slurry is within the range of 20000-40000 mPa·s, adding a cation exchange resin and stirring for a period of time, thereby completing the raw material pretreatment.

[0006] In some embodiments, the dilute acid is an organic acid with a concentration of 0.05–0.3 M, preferably 0.1–0.2 M.

[0007] In some embodiments, the organic acid is preferably sulfuric acid.

[0008] In some embodiments, the amount of dilute acid used is more than 1.5 times the mass of the raw material, preferably more than 2 times, such as 1.5 to 3 times or 2 to 3 times.

[0009] In some embodiments, after ultrasonic treatment, the viscosity of the slurry is 25,000–40,000 mPa·s, or 25,000–38,000 mPa·s, or 27,000–38,000 mPa·s.

[0010] In some implementations, the frequency of the ultrasound is 15–40 kHz, such as 20–35 kHz.

[0011] In some embodiments, the amount of cation exchange resin used is more than 0.1% of the slurry mass, such as more than 0.3% or more, or more than 0.5%; preferably, the amount of cation exchange resin used is 0.1 to 2.0% of the slurry mass, such as 0.3 to 2.0%, 0.5 to 1.5%, or 0.5 to 1.0%.

[0012] In some embodiments, after adding cation exchange resin to the slurry, the mixture is stirred for 5 to 60 minutes, such as 10 to 30 minutes, and then the resin is removed.

[0013] In some embodiments, the cation exchange resin is a strong acid type cation exchange resin.

[0014] In some embodiments, the acid in the acid activation treatment is an inorganic acid, preferably sulfuric acid; the acid solution is an aqueous solution of an inorganic acid with a concentration of 50% or higher, preferably 98% concentrated sulfuric acid.

[0015] In some implementations, the amount of acid used in the acid activation treatment is 20-25% of the raw material mass.

[0016] In some implementations, the acid is directly mixed with the resin-removed slurry and stirred for a period of time, such as 2 to 8 hours, preferably 3 to 6 hours or 3 to 5 hours, to complete the acid activation treatment.

[0017] In some implementations, the acid activation treatment is carried out at a temperature of 80–100°C.

[0018] In some embodiments, after acid activation treatment, the method further includes separating the obtained solid portion, washing it to neutral, drying it, and pulverizing it to obtain the activated clay.

[0019] A second aspect of the present invention provides activated clay or a decolorizing medium containing the activated clay prepared by the method described in any embodiment herein.

[0020] A third aspect of the present invention provides the application of the method described in any embodiment herein in improving the decolorization capacity and filtration speed of activated clay.

[0021] The fourth aspect of this invention provides the application of activated clay prepared by the method described in any embodiment herein as a decolorizing medium in oil refining, particularly in decolorization;

[0022] The fifth aspect of this invention provides the application of cation exchange resin in the preparation of activated clay to improve the filtration speed of activated clay.

[0023] The sixth aspect of the present invention provides the use of dilute acid and cation exchange resin in the preparation of activated clay to improve the filtration rate of activated clay; preferably, the dilute acid is as described in any embodiment herein.

[0024] A seventh aspect of the present invention provides a method for decolorizing oils, the method comprising the step of decolorizing oils using activated clay or a decolorizing medium as described in any embodiment herein.

[0025] The eighth aspect of the present invention provides a method for refining oils and fats, the method comprising the step of decolorizing the oils and fats using activated clay or a decolorizing medium as described in any embodiment herein, and one or more steps of degumming, deacidification, decolorization, deodorization and dewaxing. Detailed Implementation

[0026] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0027] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0028] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0029] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0030] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0031] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0032] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0033] This invention discovers that in the preparation process of activated clay, bentonite is first pretreated with dilute acid, and the viscosity of the slurry is controlled within a certain range by ultrasonic treatment. Then, the slurry is treated with cation exchange resin. The activated clay prepared from the slurry pretreated in this way has a significantly improved decolorization rate and filtration speed compared with the standard reference material, thus completing this invention.

[0034] Therefore, the present invention provides a method for preparing activated clay, including raw material pretreatment and acid activation treatment.

[0035] In this article, activated clay is an adsorbent made from clay (mainly bentonite) as raw material, which is subjected to inorganic acidification treatment, followed by water washing and drying. It appears as a milky white powder, is odorless, tasteless, and non-toxic, and has strong adsorption properties, capable of adsorbing colored substances, organic substances, etc.

[0036] In this article, bentonite is a non-metallic mineral with montmorillonite as its main mineral component. Montmorillonite has a 2:1 crystal structure consisting of two silicon-oxygen tetrahedra sandwiching a layer of aluminum-oxygen octahedra. Due to the layered structure formed by the montmorillonite unit cells, certain cations, such as Cu, are present. 2+ Mg 2+ Na + K + Furthermore, these cations are highly unstable in their interaction with montmorillonite cells and are easily exchanged by other cations, thus exhibiting good ion exchange properties.

[0037] In this article, the decolorization ability of activated clay refers to its ability to remove pigments (including carotenoids and chlorophyll) from oils. The decolorization ability of activated clay is expressed as the decolorization rate.

[0038] In this paper, the raw materials used to prepare activated clay can be various raw materials conventionally used in the preparation of activated clay in this art, mainly clay, and more importantly bentonite. Various types of bentonite used in the art for preparing activated clay can be used in this invention.

[0039] In this article, the pretreatment of raw materials includes mixing the raw materials with dilute acid, ultrasonic treatment, and treatment with acidic cation exchange resin in sequence.

[0040] In this document, the dilute acid can be any acid commonly used in acid activation treatment in the art, such as an inorganic acid, but with a concentration significantly lower than that used in conventional acid activation treatment. Specifically, the concentration of the dilute acid can be 0.05–0.3 M, preferably 0.1–0.2 M. In some embodiments, the dilute acid is dilute sulfuric acid. The amount of dilute acid used is typically 1.5 times or more the mass of the raw material, preferably 2 times or more, such as 1.5–3 times or 2–3 times. The dilute acid can be mixed evenly with the raw material before ultrasonic treatment.

[0041] In this paper, the purpose of ultrasonic-assisted dilute sulfuric acid pretreatment of bentonite includes breaking down large particles to achieve a more uniform particle size distribution and removing impurities from the surface of bentonite particles to promote subsequent acid activation. This invention has found that controlling the viscosity of the slurry obtained by ultrasonic treatment of the raw material and dilute acid within the range of 20,000-40,000 mPa·s helps improve the filtration speed and decolorizing power of activated clay. Therefore, in some embodiments, the present invention performs ultrasonic treatment until the slurry viscosity is 20,000–40,000 mPa·s. In some embodiments, the ultrasonic treatment is performed until the slurry viscosity is 25,000–40,000 mPa·s. In some embodiments, the ultrasonic treatment is performed until the slurry viscosity is 25,000–38,000 mPa·s. In some embodiments, the ultrasonic treatment is performed until the slurry viscosity is 27,000–38,000 mPa·s. There are no particular limitations on the frequency and time of ultrasonic treatment, as long as the viscosity of the slurry can be controlled within the range described herein. Generally speaking, the lower the ultrasonic frequency, the shorter the ultrasonic treatment time; the higher the ultrasonic intensity, the higher the viscosity of the slurry after ultrasonic treatment. In an exemplary embodiment, the ultrasonic frequency is 15–40 kHz, such as 20–35 kHz. It should be understood that during ultrasonic treatment, the viscosity of the slurry can be sampled and tested as needed, and ultrasonic treatment can be stopped when the viscosity falls within the range defined in this application.

[0042] In this paper, once the viscosity of the slurry reaches the set value, cation exchange resin is added to the slurry, stirred for a period of time, and then the resin is removed. As is well known in the art, cation exchange resins can exchange ions with cations in solution and are classified into strong acid cation exchange resins (generally containing strongly acidic reactive groups such as sulfonic acid groups) and weak acid cation exchange resins (generally containing weaker reactive groups such as carboxyl groups). Ion exchange resins can be classified into styrene-based resins and acrylic-based resins according to their matrix type, and into gel-type and macroporous types according to their physical structure. In this paper, considering the presence of cations such as Cu in the layered structure formed by montmorillonite unit cells... 2+ Mg 2+ Since cation exchange resins can exchange ions with cations in solution, various existing cation exchange resins (including gel-type and macroporous cation exchange resins) can be used in this invention. In some embodiments, since strong acid cation exchange resins mainly contain strongly acidic reactive groups such as sulfonic acid groups (-SO3H) and can exchange all cations, strong acid cation exchange resins are preferably used in this invention. Exemplary strong acid cation exchange resins include Amberlite IMAC HP1110, and weak acid cation exchange resins include DOWEX MAC-3.

[0043] In this document, an appropriate amount of cation exchange resin may be used depending on the presence of cations in the raw material. For example, the amount of cation exchange resin may be 0.1% or more of the slurry mass, such as 0.3% or more, or 0.5% or more. In some embodiments, the amount of cation exchange resin may be 0.1% to 2.0% of the slurry mass, such as 0.3% to 2.0%, 0.5% to 1.5%, or 0.5% to 1.0%.

[0044] In this paper, after adding cation exchange resin to the slurry, the mixture can be stirred for a period of time, such as 5–60 minutes or 10–30 minutes, depending on the amount of material, and then the resin is removed. The resin can be removed using methods conventional in the art, such as sieving. The sieve openings should be large enough to retain the resin while allowing the slurry to pass through. In some embodiments, the mixture of slurry and resin is passed through a 40-mesh sieve, thus completing the pretreatment of the raw materials.

[0045] In this paper, the acid activation treatment can be carried out using conventional methods in the art, but the amount of acid used and the treatment time can be reduced. The acid can be an inorganic acid conventionally used in the art for acid activation treatment of bentonite, especially sulfuric acid. The acid is usually highly concentrated sulfuric acid, such as 50% or more, preferably 98% concentrated sulfuric acid. The amount of acid used for acid activation treatment can be 20-25% of the raw material mass. Typically, the acid is directly mixed with the resin-removed slurry, and then stirred for a period of time, such as 2-8 hours, preferably 3-6 hours or 3-5 hours, to complete the acid activation treatment. The acid activation treatment can be carried out at a temperature of 80-100°C.

[0046] After acid activation treatment, the solid fraction can be separated, washed until neutral, dried, and pulverized to obtain the activated clay described herein. Separation, washing, drying, and pulverization can be performed using conventional techniques in the art. For example, the activated slurry can be pressure filtered. In this paper, the dried solid can be pulverized to a powder >200 mesh.

[0047] In some embodiments, the pretreatment described herein includes a step of removing impurities from the raw material, such as bentonite. Impurities mainly include sand and soluble impurities. This pretreatment involves soaking the bentonite in water, stirring thoroughly, and then filtering to remove impurities such as sand and gravel. Soluble impurities dissolve in the water and are removed. Typically, an appropriate amount of water is used for soaking, depending on the quality of the bentonite, such as 3-10 times the weight of the bentonite in water. The soaking time should be sufficient to remove impurities, for example, 10 to 90 minutes, preferably 30 to 70 minutes. After soaking and filtering, the material can be dried at a low temperature before undergoing the pretreatment described herein. Typically, low-temperature drying can be performed at a temperature below 400°C, such as below 300°C (preferably 100-200°C).

[0048] In some implementation schemes, raw materials such as bentonite are ground through a 40-mesh sieve, and then the sieved raw materials are treated with dilute acid.

[0049] The activated clay prepared by the method described above in this invention has high decolorization ability and fast filtration speed.

[0050] Therefore, in some embodiments, the present invention provides the application of the preparation method described in any embodiment of this document in improving the decolorization ability and filtration speed of activated clay.

[0051] In some embodiments, the present invention provides activated clay prepared using any of the methods described above.

[0052] In some embodiments, the present invention provides a decolorizing medium containing activated clay prepared by the method described in any embodiment of the present invention.

[0053] The present invention also provides the application of activated clay prepared by the method described in any embodiment of the present invention as a decolorizing medium in oil refining, especially in decolorization.

[0054] This invention also provides a method for decolorizing oils, the method comprising the step of decolorizing the oils using the activated clay described herein. Except for using the activated clay shown herein, other process parameters for decolorization can be performed according to techniques known in the art. In some embodiments, the method further comprises the step of preparing the activated clay using any of the methods described in this invention.

[0055] This invention also provides a method for refining oils and fats, the method comprising the step of decolorizing the oils and fats using the bleaching clay; preferably, the method further comprises one or more of degumming, deacidification, decolorization, deodorization, and dewaxing. In some embodiments, the method further comprises the step of preparing the activated bleaching clay using any of the methods described in this invention. The degumming, deacidification, deodorization, and dewaxing described herein can be performed using any existing technology.

[0056] In some embodiments, the present invention also provides the use of cation exchange resins in the preparation of activated clay to improve the filtration rate of activated clay. In some embodiments, the preparation is the preparation of activated clay as described in any embodiment of this application. The cation exchange resin may be as described in any embodiment of this application.

[0057] In some embodiments, the present invention also provides the use of dilute acid and cation exchange resin in the preparation of activated clay to improve the filtration rate of activated clay. In some embodiments, the preparation is the preparation of activated clay as described in any embodiment of this application. The dilute acid and cation exchange resin may be as described in any embodiment of this application.

[0058] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Percentages and parts are by weight unless otherwise stated.

[0059] The following examples and comparative examples use the following methods:

[0060] Determination of decolorization rate and decolorization power of activated clay:

[0061] Weigh 110g (accurate to 0.01g) of neutralized soybean oil into a flat-bottomed three-necked flask, evacuate the vacuum, and stir at 100rpm. Heat the neutralized soybean oil to 105±2℃, then add 1.10g of activated clay sample (accurate to 0.001g). Continue stirring under vacuum. After 30 minutes, stop heating and cool the material to below 60℃ without breaking the vacuum. Filter to obtain the decolorized oil. Determine the red value (R) and yellow value (Y) of the oil using a Lovibond colorimeter (PFX995).

[0062] The decolorization rate of activated clay is calculated using the following formula:

[0063] Decolorization rate = 100% * [(10R + Y)] 前 -(10R+Y) 后 )] / (10R+Y) 前Where R and Y are the red and yellow values ​​of the oil as determined by the Lovibond colorimeter, respectively;

[0064] (10R+Y) 前 This refers to the color value of the oil before bleaching;

[0065] (10R+Y) 后 It refers to the color value of the oil after decolorization.

[0066] The decolorizing power of activated clay is calculated using the following formula:

[0067] Decolorization power = 100% * (Decolorization rate of soil to be tested / Decolorization rate of standard soil).

[0068] Filtration rate determination: Refer to GB 25571-2011 National Food Safety Standard for Food Additives - Activated Clay.

[0069] Viscosity determination: Refer to GB / T 10247-2008 Viscosity Measurement Method.

[0070] In the following examples and comparative examples, the strong acid cation exchange resin used was Amberlite IMACHP1110, and the weak acid cation exchange resin used was DOWEX MAC-3.

[0071] Both the standard soil and bentonite were supplied by Yihai Kerry (Jiangxi) Technology Co., Ltd.

[0072] Example 1

[0073] Bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with 0.2M dilute sulfuric acid (the amount of sulfuric acid was twice the mass of the bentonite). After stirring evenly, the mixture was ultrasonically treated at 35kHz until the slurry viscosity reached 27877 mPa·s. 0.5 wt% of a strong acidic cation exchange resin was added to the ultrasonically treated slurry, and after stirring for 10 minutes, the mixture was passed through a 40-mesh sieve to remove the resin.

[0074] Concentrated sulfuric acid (98% concentration) accounting for 25% of the bentonite mass was added to the slurry after sieving, and the mixture was stirred at 80°C for 5 hours. The slurry after the reaction was completed was filtered by pressure, washed until neutral, dried, and then pulverized to obtain activated clay 1 with a mesh size >200.

[0075] Example 2

[0076] Bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with 0.1M dilute sulfuric acid (the amount of sulfuric acid was three times the mass of the bentonite). After stirring evenly, the mixture was ultrasonically treated at 28kHz until the slurry viscosity reached 32024 mPa·s. 0.7 wt% of a strong acidic cation exchange resin was added to the ultrasonically treated slurry, and after stirring for 20 minutes, the mixture was passed through a 40-mesh sieve to remove the resin.

[0077] Concentrated sulfuric acid (98% concentration) accounting for 22% of the bentonite mass was added to the slurry after sieving, and the mixture was stirred at 90°C for 3 hours. The slurry after the reaction was completed was filtered by pressure, washed until neutral, dried, and then pulverized to obtain activated clay 2 with a mesh size >200.

[0078] Example 3

[0079] Bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with 0.2M dilute sulfuric acid (2.5 times the mass of the bentonite). After thorough mixing, the mixture was ultrasonically treated at 20kHz until the slurry viscosity reached 37711 mPa·s. 1.0 wt% of a strong acidic cation exchange resin was added to the ultrasonically treated slurry, and after stirring for 30 minutes, the mixture was passed through a 40-mesh sieve to remove the resin.

[0080] Concentrated sulfuric acid (98% concentration) accounting for 20% of the bentonite mass was added to the sieved slurry, and the mixture was stirred at 100℃ for 4 hours. The slurry after the reaction was completed was filtered, washed until neutral, dried, and then pulverized to obtain activated clay 3 with a mesh size >200.

[0081] Example 4 (with weak acid cation exchange resin)

[0082] Using the same method as in Example 3, bentonite ore was fed into a crusher for coarse crushing, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities from the ground bentonite, it was mixed with 0.2M dilute sulfuric acid, with the amount of dilute sulfuric acid being 2.5 times the mass of bentonite. After stirring evenly, it was ultrasonically treated at 20kHz until the slurry viscosity was 37711 mPa·s.

[0083] Add 1.0 wt% of weakly acidic cation exchange resin to the ultrasonically treated slurry, stir for 30 min, and then pass it through a 40-mesh sieve to remove the resin.

[0084] Add concentrated sulfuric acid (98% concentration) at 20% of the bentonite mass to the slurry after sieving, and stir at 100℃ for 4 hours. Filter the reacted slurry, wash until neutral, dry, and pulverize to obtain activated clay 4 with a mesh size >200.

[0085] Example 5

[0086] Using the same method as in Example 3, bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with 0.2M dilute sulfuric acid (2.5 times the mass of the bentonite), stirred evenly, and then ultrasonically treated at 20kHz until the slurry viscosity reached 39891 mPa·s. 1 wt% of a strong acidic cation exchange resin was added to the ultrasonically treated slurry, stirred for 30 minutes, and then passed through a 40-mesh sieve to remove the resin.

[0087] Add concentrated sulfuric acid (98% concentration) at 20% of the bentonite mass to the sieved slurry, and stir at 100℃ for 4 hours. Filter the reacted slurry, wash until neutral, dry, and pulverize to obtain activated clay 5 with a mesh size >200.

[0088] Example 6

[0089] Using the same method as in Example 3, bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with 0.2M dilute sulfuric acid (2.5 times the mass of the bentonite), stirred evenly, and then ultrasonically treated at 20kHz until the slurry viscosity reached 37711 mPa·s. 1.0 wt% of a strong acidic cation exchange resin was added to the ultrasonically treated slurry, stirred for 30 min, and then passed through a 40-mesh sieve to remove the resin.

[0090] Add a 50% sulfuric acid solution (48% of the bentonite mass) to the sieved slurry and stir at 100°C for 4 hours. Filter the reacted slurry, wash until neutral, dry, and pulverize to obtain activated clay 6 with a mesh size >200.

[0091] Comparative Example 1 (no pretreatment, no resin added)

[0092] Bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with water (2.5 times the weight of the bentonite), and then concentrated sulfuric acid (98% concentration) at 30% of the bentonite weight was added. The mixture was stirred at 100°C for 5 hours. The resulting slurry was then filtered, washed until neutral, dried, and pulverized to obtain activated clay 7 with a mesh size >200.

[0093] Comparative Example 2 (High Slurry Viscosity)

[0094] Bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with 0.2M dilute sulfuric acid (the amount of sulfuric acid was twice the mass of the bentonite). After stirring evenly, the mixture was ultrasonically treated at 35kHz until the slurry viscosity reached 53554 mPa·s. 0.5 wt% of a strong acidic cation exchange resin was added to the ultrasonically treated slurry, and after stirring for 10 minutes, the mixture was passed through a 40-mesh sieve to remove the resin.

[0095] Concentrated sulfuric acid (98% concentration) accounting for 25% of the bentonite mass was added to the sieved slurry, and the mixture was stirred at 80°C for 5 hours. The slurry after the reaction was completed was filtered, washed until neutral, dried, and then pulverized to obtain activated clay 8 with a mesh size >200.

[0096] Comparative Example 3 (high slurry viscosity, no resin added)

[0097] Using the same method as Comparative Example 2, bentonite ore was fed into a crusher for coarse crushing, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities from the ground bentonite, it was mixed with 0.2M dilute sulfuric acid, with the amount of dilute sulfuric acid being twice the mass of the bentonite. After stirring evenly, it was ultrasonically treated at 35kHz until the slurry viscosity reached 53554 mPa·s.

[0098] Concentrated sulfuric acid (98% concentration) accounting for 25% of the bentonite mass was added to the slurry, and the mixture was stirred at 80°C for 5 hours. The slurry after the reaction was completed was filtered, washed until neutral, dried, and then pulverized to obtain activated clay 9 with a mesh size >200.

[0099] Comparative Example 4 (low slurry viscosity)

[0100] Bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with 0.2M dilute sulfuric acid (2.5 times the mass of the bentonite). After thorough mixing, the mixture was ultrasonically treated at 20kHz until the slurry viscosity reached 13623 mPa·s. 1.0 wt% of a strong acidic cation exchange resin was added to the ultrasonically treated slurry, and after stirring for 30 minutes, the mixture was passed through a 40-mesh sieve to remove the resin.

[0101] Concentrated sulfuric acid (98% concentration) accounting for 20% of the bentonite mass was added to the sieved slurry, and the mixture was stirred at 100°C for 4 hours. The slurry after the reaction was completed was filtered, washed until neutral, dried, and then pulverized to obtain activated clay 10 with a mesh size >200.

[0102] Comparative Example 5 (low slurry viscosity, no resin added)

[0103] Using the same method as Comparative Example 4, bentonite ore was fed into a crusher for coarse crushing, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities from the ground bentonite, it was mixed with 0.2M dilute sulfuric acid, with the amount of dilute sulfuric acid being 2.5 times the mass of bentonite. After stirring evenly, it was ultrasonically treated at 20kHz until the slurry viscosity reached 13623 mPa·s.

[0104] Concentrated sulfuric acid (98% concentration) accounting for 20% of the bentonite mass was added to the slurry, and the mixture was stirred at 100°C for 4 hours. The slurry after the reaction was completed was filtered, washed until neutral, dried, and then pulverized to obtain activated clay 11 with a mesh size >200.

[0105] Comparative Example 6 (slurry viscosity moderate, no resin added)

[0106] The bentonite ore is fed into a crusher for coarse crushing, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities from the ground bentonite, it is mixed with 0.1M dilute sulfuric acid, with the amount of dilute sulfuric acid being 3 times the mass of the bentonite. After stirring evenly, it is ultrasonically treated at 28kHz until the slurry viscosity reaches 32024mPa·s.

[0107] Concentrated sulfuric acid (98% concentration) accounting for 22% of the bentonite mass was added to the slurry, and the mixture was stirred at 90°C for 3 hours. The slurry after the reaction was completed was filtered by pressure, washed until neutral, dried, and then pulverized to obtain activated clay 12 with a mesh size >200.

[0108] Comparative Example 7 (pretreatment without acid)

[0109] Bentonite ore was coarsely crushed in a crusher, then ground and sieved to obtain bentonite with a mesh size of 40 or larger. After removing impurities, the ground bentonite was mixed with pure water (3 times the mass of the bentonite) and stirred evenly. The mixture was then ultrasonically treated at 28 kHz until the slurry viscosity reached 30274 mPa·s. 0.7 wt% of a strong acidic cation exchange resin was added to the ultrasonically treated slurry, and after stirring for 20 minutes, the mixture was passed through a 40-mesh sieve to remove the resin.

[0110] Concentrated sulfuric acid (98% concentration) accounting for 22% of the bentonite mass was added to the slurry after sieving, and the mixture was stirred at 90°C for 3 hours. The slurry after the reaction was completed was filtered by pressure, washed until neutral, dried, and then pulverized to obtain activated clay 13 with a mesh size >200.

[0111] The decolorization rate, decolorization power, and filtration speed of the activated clay obtained in the above embodiments and comparative examples were tested according to the methods described above, and the results are listed in Table 1 below.

[0112] Table 1

[0113]

[0114]

Claims

1. A process for the preparation of activated earth, characterized in that, The method includes raw material pretreatment and acid activation treatment. The raw material pretreatment includes mixing the raw material with dilute acid to obtain a slurry, ultrasonically treating the slurry, and adding a cation exchange resin after the viscosity of the slurry is within the range of 20,000-40,000 mPa·s, stirring for a period of time to complete the pretreatment of the raw material.

2. The method as described in claim 1, characterized in that, The dilute acid is an organic acid with a concentration of 0.05–0.3 M, preferably 0.1–0.2 M; the organic acid is preferably sulfuric acid. Preferably, the amount of dilute acid used is more than 1.5 times the mass of the raw material, more preferably more than 2 times, such as 1.5 to 3 times or 2 to 3 times.

3. The method as described in claim 1 or 2, characterized in that, After ultrasonic treatment, the viscosity of the slurry is 25,000–40,000 mPa·s, or 25,000–38,000 mPa·s, or 27,000–38,000 mPa·s; Preferably, the frequency of the ultrasound is 15–40 kHz, such as 20–35 kHz.

4. The method as described in claim 1 or 2, characterized in that: The amount of cation exchange resin used is 0.1% or more of the slurry mass, such as 0.3% or more or 0.5% or more; preferably, the amount of cation exchange resin used is 0.1-2.0% of the slurry mass, such as 0.3-2.0%, 0.5-1.5%, or 0.5-1.0%; and / or After adding cation exchange resin to the slurry, stir for 5 to 60 minutes, or 10 to 30 minutes, and then remove the resin. Preferably, the cation exchange resin is a strong acid type cation exchange resin.

5. The method as described in claim 1 or 2, characterized in that, In the acid activation treatment, the acid is an inorganic acid, preferably sulfuric acid; the acid solution is an aqueous solution of an inorganic acid with a concentration of 50% or higher, preferably 98% concentrated sulfuric acid; Preferably, the amount of acid used in the acid activation treatment is 20-25% of the raw material mass; Preferably, the acid is directly mixed with the resin-removed slurry and stirred for a period of time, such as 2 to 8 hours, preferably 3 to 6 hours or 3 to 5 hours, to complete the acid activation treatment; Preferably, the acid activation treatment is carried out at a temperature of 80–100°C.

6. The method as described in claim 1, characterized in that, After acid activation treatment, the method further includes separating the obtained solid part, washing it to neutral, drying it and pulverizing it to obtain the activated clay.

7. Activated clay or a decolorizing medium containing the activated clay prepared by any one of claims 1 to 6.

8. Selected from the following applications: (1) The application of the method according to any one of claims 1 to 6 in improving the decolorization capacity and filtration speed of activated clay; (2) The application of activated clay prepared by any one of claims 1 to 6 as a decolorizing medium in oil refining, especially in decolorization; (3) Application of cation exchange resins in the preparation of activated clay to improve its filtration rate; and (4) Application of dilute acid and cation exchange resin in the preparation of activated clay to improve the filtration speed of activated clay; preferably, the dilute acid is as described in claim 2.

9. A method for decolorizing oils, characterized in that, The method includes the step of decolorizing oils using the activated clay or decolorizing medium as described in claim 7.

10. A method for refining oils, characterized in that, The method includes the step of decolorizing oils using the activated clay or decolorizing medium as described in claim 7, and one or more steps of degumming, deacidification, decolorization, deodorization and dewaxing.

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