A method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water.

Abstract

This application belongs to the technical field of oil refining, specifically disclosing a method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment. The method includes the following steps: pre-treating tap water sequentially through a multi-media filter and an activated carbon filter to remove suspended solids, residual chlorine, and organic matter, obtaining pre-treated water; desalinating the pre-treated water through a first-stage reverse osmosis membrane module to obtain first-stage permeate; further desalinating the first-stage permeate through a second-stage reverse osmosis membrane module to obtain ultra-low chlorine pure water; and applying the ultra-low chlorine pure water to the following stages of peanut oil refining: (a) water for hydration and degumming; (b) water for alkali refining and washing; and (c) direct steam for deodorization. This application completely cuts off the pathway for the introduction of exogenous chloride ions, reducing the 3-chloropropanol ester content in the finished peanut oil and improving the safety and quality of edible oil.

Description

Technical Field

[0001] This application relates to the technical field of oil refining, and in particular to a method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water. Background Technology

[0002] Edible vegetable oils produce a variety of potentially harmful substances during high-temperature refining. Among them, 3-chloropropanol esters and their hydrolysis product 3-chloropropanol have nephrotoxicity, reproductive toxicity, immunosuppression and potential carcinogenicity, and therefore have attracted widespread attention.

[0003] During the refining processes of peanut oil, such as hydration degumming, alkali refining and washing, and high-temperature vacuum deodorization, chlorine-containing precursors are easily introduced. Under high-temperature and high-vacuum conditions, esterification and chlorination side reactions occur, generating large amounts of 3-chloropropanol esters. This results in the finished peanut oil exceeding safety standards, severely limiting the quality and market grade of peanut oil products. In the hydration and alkali refining processes of peanut oil, chloride ions accumulate in the oil phase along with gum and soap residues. In the high-temperature deodorization section, chloride ions accumulated in the oil system readily undergo violent chlorination reactions with glycerol and fatty acids, which is the main exogenous source of 3-chloropropanol esters.

[0004] Existing conventional water purification processes only employ simple sand filtration, carbon filtration, or single-stage reverse osmosis treatment, resulting in low precision in removing chloride ions and trace organic chlorine precursors from the water, and the effluent quality cannot meet the requirements for ultra-low chlorine refining of peanut oil.

[0005] In summary, the current peanut oil refining industry lacks a systematic process for controlling chlorine at the source of the process water and precisely blocking the formation of 3-chloropropanol esters throughout the entire refining process. This results in technical shortcomings such as insufficient precision in water dechlorination, incomplete removal of chlorine precursors, poor oil stability due to toxicity, and high costs for downstream treatment. Therefore, developing a process that can deeply prepare ultra-low chlorine refining water, is suitable for the entire peanut oil refining process, and efficiently inhibits the formation of 3-chloropropanol esters has significant production application value and industry promotion significance. Summary of the Invention

[0006] To address the issue of insufficient chlorination precision in water sources, this application provides a method for suppressing the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water.

[0007] This application provides a method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water, employing the following technical solution: A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment includes the following steps: (1) Tap water is pretreated by passing it through a multi-media filter and an activated carbon filter in sequence to remove suspended solids, residual chlorine and organic matter to obtain pretreated water; (2) The pretreated water obtained in step (1) is desalinated by passing it through a first-stage reverse osmosis membrane module at an operating pressure of 1.0-1.6 MPa to obtain first-stage permeate; (3) The primary permeate obtained in step (2) is subjected to secondary desalination treatment at an operating pressure of 1.0-1.6 MPa through a secondary reverse osmosis membrane module to obtain ultra-low chlorine pure water; (4) Apply the ultra-low chlorine pure water obtained in step (3) to the following steps of peanut oil refining: (a) water for hydration and degumming; (b) water for alkali refining and washing; (c) direct steam for deodorization.

[0008] By adopting the above technical solutions, the multi-media filter intercepts sediment, colloids, and suspended impurities in tap water, preventing large particles from scratching the reverse osmosis membrane surface and clogging the membrane element channels, thus protecting the stable operation of downstream reverse osmosis units. The activated carbon filter adsorbs residual chlorine, small molecule organic matter, and discolored and odorous substances in the water. Removing residual chlorine prevents oxidation and damage to the polyamide reverse osmosis membrane, extending its service life, while retaining organic matter prevents organic fouling of the membrane surface.

[0009] Under set pressure, the membrane removes most inorganic salt ions, chloride ions, and residual trace colloids by using reverse osmosis screening and ion retention. This initially reduces the chlorine content and conductivity of the water. The primary permeate after initial desalination significantly reduces the chloride ion load and alleviates the pressure on the secondary reverse osmosis treatment. This is a key pre-desalination process for producing ultra-low chlorine pure water.

[0010] The primary product water undergoes deep desalination and dechlorination, retaining residual trace amounts of chloride ions and soluble salts to ultimately produce ultra-low chlorine pure water. This process strictly controls chloride ion levels at the water source, eliminating external sources of chlorine impurities and providing low-chlorine process water for subsequent refining processes.

[0011] Water used for hydration and degumming: Conventional tap water contains chloride ions, which are mixed into the oil phase along with phospholipids and gums during the hydration stage. Using ultra-low chlorine pure water eliminates the entry of exogenous chlorine into the crude oil during hydration, reducing the amount of chloropropanol ester precursors in subsequent processes. Water used for alkali refining and washing: Alkali refining and washing is one of the main processes for enriching chloride ions in oils. Low-chlorine washing water avoids chloride ions remaining in the oil during the washing process, reducing the chloride ion content of the oil.

[0012] Deodorization direct steam water: Under high temperature (above 230℃) conditions for deodorization, chloride ions in oils readily react with glycerol and fats to form 3-chloropropanol esters; deodorization steam is prepared from ultra-low purity water, and no chlorine is introduced into the high temperature system, thus inhibiting the synthesis reaction of 3-chloropropanol esters from the source.

[0013] By uniformly replacing the key water used in the entire refining process with two-stage reverse osmosis ultra-low chlorine pure water, the entire process cuts off the path of external chloride ion introduction. This is different from the existing process of removing 3-chloropropanol esters in the finished oil, achieving source control, reducing the 3-chloropropanol ester content of finished peanut oil, and improving the safety and quality of edible oil.

[0014] Preferably, in step (3), before the secondary reverse osmosis treatment, the primary permeate is degassed to remove carbon dioxide, and then an alkaline solution is added to adjust the pH to 8.0-8.5.

[0015] By adopting the above technical solution, the first-stage reverse osmosis permeate dissolves a large amount of CO2. Direct alkali addition will preferentially react with CO2 and consume the alkali solution. Pre-degassing removes most of the gaseous CO2, reduces the amount of NaOH to be fed, and avoids the introduction of additional Na⁺ and trace amounts of chloride ion impurities by excessive alkali, thereby reducing the introduction of external chlorine into the pure water system from the source.

[0016] Preferably, in step (4)(a), the amount of ultra-low chlorine pure water added during hydration degumming is 2-5% of the oil weight, the degumming temperature is 60-80℃, and the degumming time is 30-60min.

[0017] By adopting the above technical solution, the water addition ratio is the optimal range for peanut oil hydration and degumming. It can fully wet and swell the hydrophilic gums and phospholipids in the oilseeds, promote the rapid coagulation and precipitation of gums, and ensure a good degumming effect. At the same time, it can avoid the system emulsification and oil-water separation difficulties caused by excessive water addition. Meanwhile, it can strictly control the water consumption, minimize the introduction of external water bodies, completely eliminate the introduction of chloride ions from conventional water, and reduce the content of chloride precursors in oil from the source.

[0018] Preferably, in step (4)(b), the amount of ultra-low chlorine pure water added during alkali refining and washing is 10-20% of the oil weight, the washing temperature is 80-95℃, and the number of washing times is 1-3.

[0019] By adopting the above technical solution, the water addition ratio can fully dilute and wash away residual soap particles, free fatty acids and trace impurities in the oil phase, ensuring the cleanliness of the oil after alkali refining; it is adapted to the characteristics of peanut oil alkali refining water washing process, and the sufficient water volume can achieve thorough washing, avoiding the impact of saponification residue on oil quality. At the same time, ultra-low chlorine pure water with chloride ions ≤0.5mg / L is used throughout the process, strictly avoiding the introduction of a large amount of chloride ions by conventional washing water, greatly reducing the enrichment of chlorine precursor substances in the oil, and blocking the source of 3-chloropropanol ester formation from the key process.

[0020] Preferably, in step (4)(c), the deodorization temperature is 200-240℃, the deodorization time is 60-120min, the vacuum degree is 0.2-0.6kPa, and the steam injection amount is 10-20% of the oil weight.

[0021] By adopting the above technical solution, this temperature range can effectively vaporize and remove free fatty acids, aldehydes and ketones, and volatile impurities from peanut oil, improving the flavor and color of the oil. At the same time, this temperature is a conventional and controllable high-temperature range for oil deodorization. Combined with an ultra-low chlorine vapor system, it prevents exogenous chloride ions from undergoing chlorination side reactions with glycerol and polar groups of oils under high-temperature conditions. It blocks the synthesis pathway of 3-chloropropanol ester from the core temperature field, avoiding the problem of high-temperature toxicity caused by chlorine in conventional industrial water.

[0022] Preferably, in step (1), the activated carbon filter is filled with granular activated carbon, and the activated carbon pretreatment includes the following: Coconut shell charcoal, zeolite, and copper sulfate are heated at 300-350℃ for 2-3 hours under nitrogen protection, ground, mixed with modified clay, ground, and sieved to obtain pretreated activated carbon.

[0023] By adopting the above technical solutions, coconut shell activated carbon possesses advantages such as well-developed pores, large specific surface area, and high mechanical strength. As an adsorption substrate, it can provide sufficient adsorption sites, stably ensuring the cleanliness of subsequent reverse osmosis feed water. Zeolite has a regular porous structure and excellent ion exchange performance, which can assist in the adsorption of trace colloids, suspended solids, and some metal ions in water, further reducing the impurity content of the water. At the same time, zeolite can optimize the pore structure of the activated carbon layer, prevent activated carbon from caking and clogging, maintain the permeability and stability of the filter layer, and ensure the continuous and stable water flow of the pretreatment system.

[0024] High-temperature calcination under a nitrogen inert atmosphere can prevent the activated carbon from being oxidized and burned at high temperatures, while fixing the structure of the active components. Copper sulfate, as a copper source, decomposes into copper oxide during heating and is loaded onto the surface of coconut shell charcoal and zeolite. Copper oxide has a certain chemical adsorption effect on chloride ions and can form copper oxychloride or complexes, thereby enhancing the material's targeted removal ability of chloride ions.

[0025] High-temperature calcination followed by grinding breaks up agglomerated particles, exposing more active adsorption sites. After compounding with modified clay and grinding again to ensure uniform mixing, the modified clay exhibits excellent adsorption, flocculation, impurity removal, and decolorization properties. It can work synergistically with activated carbon to adsorb trace amounts of colloids, polar organic matter, and residual impurities in the water, further improving the water purification precision.

[0026] Compared to ordinary activated carbon, the composite activated carbon filter media pretreated by this process has significantly improved capabilities in removing residual chlorine, organic matter, and trace amounts of chlorine precursors. It can minimize the amount of impurities and initial chlorine load in raw water, effectively protect reverse osmosis membrane elements, extend membrane life, and ensure the stable production of ultra-low chlorine pure water from the two-stage reverse osmosis system. It forms a multi-level chlorine control barrier from the water source front end, precisely meeting the process requirements for suppressing 3-chloropropanol esters in peanut oil refining.

[0027] Preferably, the mass ratio of the coconut shell charcoal, zeolite, and copper sulfate is 5-6:2-2.5:1.

[0028] By adopting the above technical solutions, coconut shell charcoal provides high specific surface area and microporous structure, which is responsible for physical adsorption; zeolite provides ion exchange capacity and molecular sieve effect, which is responsible for ion exchange and pore channel regulation; and copper sulfate is converted into copper oxide after calcination, which provides chemical adsorption sites for chloride ions.

[0029] Coconut shell charcoal provides a dispersion carrier for CuO, preventing agglomeration. Zeolite removes cations, optimizing the microenvironment for CuO chemisorption. The pores of coconut shell charcoal provide confined space for ion exchange and chemical reactions, improving efficiency.

[0030] Compared to using coconut shell activated carbon alone, the combined use of these three agents significantly improves the removal rate of residual chlorine and organic chlorine precursors in raw water. This reduces the chlorine content in the influent during the pretreatment stage, alleviates the load on the subsequent two-stage reverse osmosis dechlorination, ensures the stable production of ultra-low chlorine pure water at the downstream end, reduces the introduction of chloride ions into the peanut oil refining system from the source of water, and ultimately achieves the invention's objective of inhibiting the formation of 3-chloropropanol esters.

[0031] Preferably, the modified clay is prepared as follows: the clay is dispersed in a sodium hydroxide solution, soaked for 1-2 hours, washed with water, then dispersed in deionized water, carbon nanotubes are added, stirred for 20-25 minutes, filtered, then sprayed with an aqueous polyurethane solution, and dried to obtain the modified clay.

[0032] By adopting the above technical solution, sodium hydroxide solution is used to etch the pores on the surface of bleaching clay, opening up the closed micropores inside the bleaching clay and increasing the specific surface area and porosity; at the same time, impurities, acidic groups and soluble inorganic salts on the surface of bleaching clay are removed, thereby improving the surface activity and adsorption performance of bleaching clay and enhancing its ability to capture trace organic matter, colloids and chlorine-containing intermediates in water.

[0033] Carbon nanotubes possess ultra-high specific surface area, excellent electrical conductivity and adsorption properties, and a one-dimensional tubular porous structure. When uniformly loaded onto the pores and surface of kaolin, they can be further used to construct multi-level composite porous structures. This significantly enhances the adsorption and capture capacity of the composite material for trace organic pollutants, residual chloramines, and polar impurities, while also strengthening the structural stability of the filter media and preventing structural collapse and performance degradation caused by long-term water flow erosion.

[0034] Waterborne polyurethane can form an ultra-thin, flexible coating and bonding layer on the surface of clay and carbon nanotubes, firmly locking the carbon nanotubes inside the pore structure of the clay and preventing the functional components from falling off and being lost during operation. At the same time, it can moderately close large pores and optimize pore size distribution, thereby improving the selective adsorption capacity of the filter media, preferentially adsorbing organic chlorine-containing impurities, and reducing ineffective adsorption.

[0035] This modified clay, after alkali activation, carbon nanotube composite, and polyurethane immobilization modification, possesses excellent performance in removing organic matter, trace chlorine precursors, and colloidal purification. When used in combination with the coconut shell carbon-zeolite-copper sulfate composite system, it can synergistically purify raw water, further reduce organic chlorine and residual impurities in the influent, significantly reduce the dechlorination load of the two-stage reverse osmosis system, ensure the stable production of ultra-low chlorine process water from the pure water system, block the external chlorine input in peanut oil refining from the source, and effectively inhibit the formation of 3-chloropropanol ester.

[0036] Preferably, the mass ratio of the kaolin, carbon nanotubes, and aqueous polyurethane solution is 3-5:1:0.1-0.3.

[0037] By employing the above technical solution, bleached clay is used as the basic adsorbent material, carbon nanotubes as the functional reinforcing material, and an aqueous polyurethane solution as the viscous solution. Bleached clay ensures substrate stability, carbon nanotubes precisely enhance the adsorption of trace chlorine impurities, and polyurethane provides fixation and prevents detachment. The modified bleached clay, when combined with a coconut shell carbon-zeolite-copper sulfate composite system, can form multiple dechlorination barriers at the front end of water treatment, significantly reducing residual chlorine and organic chlorine precursor content in raw water, alleviating the treatment pressure on the two-stage reverse osmosis system, and stably producing ultra-low chlorine pure water. This effectively cuts off external chlorine input in the peanut oil refining process and inhibits the formation of 3-chloropropanol esters in the finished peanut oil.

[0038] In summary, this application has the following beneficial effects: 1. This application replaces the key water used in the entire refining process with two-stage reverse osmosis ultra-low chlorine pure water, cutting off the path of external chloride ion introduction throughout the entire process, achieving source control, reducing the 3-chloropropanol ester content of the finished peanut oil, and improving the safety and quality of edible oil.

[0039] 2. In this application, the activated carbon filter adsorbs residual chlorine, small molecule organic matter, and off-color and odor substances in the water. The removal of residual chlorine can prevent residual chlorine from oxidizing and damaging the polyamide reverse osmosis membrane, thus extending the membrane's service life. The retention of organic matter prevents organic fouling on the membrane surface.

[0040] 3. In this application, the primary product water undergoes deep desalination and dechlorination to remove residual trace amounts of chloride ions and soluble salts, ultimately producing ultra-low chlorine pure water, thus strictly controlling the chloride ion index from the water source. Detailed Implementation

[0041] The present application will be further described in detail below with reference to the embodiments.

[0042] The raw materials used in the examples and comparative examples are all commercially available.

[0043] Example 1 A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment, comprising the following steps: (1) Two tons of tap water were pretreated by passing them through a multi-media filter and an activated carbon filter in sequence to remove suspended solids, residual chlorine and organic matter to obtain pretreated water; the activated carbon filter was filled with granular activated carbon and the operating temperature was 35℃.

[0044] (2) The pretreated water obtained in step (1) is desalinated through a first-stage reverse osmosis membrane module at an operating pressure of 1.6 MPa to obtain first-stage permeate water; a polyamide composite reverse osmosis membrane is used and the operating temperature is 35℃.

[0045] (3) The primary permeate obtained in step (2) is subjected to secondary desalination at an operating pressure of 1.6 MPa through a secondary reverse osmosis membrane module to obtain ultra-low chlorine pure water; (4) Apply the ultra-low chlorine pure water obtained in step (3) to the following steps of peanut oil refining: (a) water for hydration and degumming; (b) water for alkali refining and washing; (c) direct steam for deodorization.

[0046] (a) Water for hydration and degumming: At 80°C, add 5% by weight of ultra-low chlorine pure water to the crude peanut oil and stir for 30 minutes to carry out hydration and degumming, and separate the degummed oil. (b) Water for washing after alkali refining: After alkali refining and deacidification, the alkali-refined oil is washed three times with ultra-low chlorine pure water at 95°C to remove residual soap residue and free alkali. (c) Direct steam for deodorization: Ultra-low chlorine pure water is converted into superheated steam by a steam generator and introduced into the deodorization tower to directly contact the oil. The deodorization temperature is controlled at 240℃, the deodorization time is 60min, the vacuum degree is controlled at 0.6kPa, and the steam injection amount is 20% of the oil weight.

[0047] In step (3), before the secondary reverse osmosis treatment, the primary permeate is degassed to remove carbon dioxide, and then an alkaline solution (sodium hydroxide solution) is added to adjust the pH to 8.5.

[0048] The activated carbon filter is filled with granular activated carbon, purchased from Fujian Yuanli Activated Carbon Co., Ltd., and the 10-20 mesh filter element is filled with coconut shell activated carbon.

[0049] Example 2: A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis treatment of water, differing from Example 1 in that it includes the following steps: (1) Tap water is pretreated by passing it through a multi-media filter and an activated carbon filter in sequence to remove suspended solids, residual chlorine and organic matter to obtain pretreated water; the activated carbon filter is filled with granular activated carbon and the operating temperature is 15℃.

[0050] (2) The pretreated water obtained in step (1) is desalinated through a first-stage reverse osmosis membrane module at an operating pressure of 1.0 MPa to obtain first-stage permeate water; a polyamide composite reverse osmosis membrane is used and the operating temperature is 15℃.

[0051] (3) The primary permeate obtained in step (2) is subjected to secondary desalination at an operating pressure of 1.0 MPa through a secondary reverse osmosis membrane module to obtain ultra-low chlorine pure water; (4) Apply the ultra-low chlorine pure water obtained in step (3) to the following steps of peanut oil refining: (a) water for hydration and degumming; (b) water for alkali refining and washing; (c) direct steam for deodorization.

[0052] (a) Water for hydration and degumming: At 60°C, add 2% by weight of ultra-low chlorine pure water to the crude peanut oil and stir for 60 min to carry out hydration and degumming, and separate the degummed oil. (b) Water for washing after alkali refining: After alkali refining and deacidification, the alkali-refined oil is washed once with ultra-low chlorine pure water at 80°C to remove residual soap residue and free alkali. (c) Direct steam for deodorization: Ultra-low chlorine pure water is converted into superheated steam by a steam generator and introduced into the deodorization tower to directly contact the oil. The deodorization temperature is controlled at 200℃, the deodorization time is 120min, the vacuum degree is controlled at 0.2kPa, and the steam injection amount is 10% of the oil weight.

[0053] In step (3), before the secondary reverse osmosis treatment, the primary permeate is degassed to remove carbon dioxide, and then an alkaline solution is added to adjust the pH to 8.0.

[0054] Example 3 A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment, differing from Example 1 in that, in step (1), the activated carbon filter is filled with granular activated carbon, and the activated carbon pretreatment includes the following: Coconut shell charcoal, zeolite, and 27 kg of copper sulfate were heated at 350°C for 2 hours under nitrogen protection, ground, mixed with 68 kg of modified clay, ground, and sieved through a 100-mesh sieve to obtain pretreated activated carbon.

[0055] The mass ratio of coconut shell charcoal, zeolite, and copper sulfate is 6:2.5:1.

[0056] The modified bleaching clay was prepared as follows: 70 kg of bleaching clay was dispersed in 120 L of 2% sodium hydroxide solution and soaked for 1 hour. After washing with water, it was dispersed in 300 L of deionized water, and 11 kg of carbon nanotubes were added. The mixture was stirred for 25 minutes, filtered, and then sprayed with 4 L of aqueous polyurethane solution. After drying, the modified bleaching clay was obtained. (1 kg of aqueous polyurethane (purchased from Hubei Langbowan Biomedical Co., Ltd.) was prepared into a 1 wt% aqueous solution to obtain the aqueous polyurethane solution.)

[0057] The mass ratio of kaolin, carbon nanotubes, and aqueous polyurethane solution is 5:1:0.3.

[0058] Example 4: A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment, differing from Example 1 in that activated carbon pretreatment is included, as follows: Coconut shell charcoal, zeolite, and 26 kg of copper sulfate were heated at 300°C for 3 hours under nitrogen protection, ground, mixed with 66 kg of modified clay, ground, and sieved through a 100-mesh sieve to obtain pretreated activated carbon.

[0059] The mass ratio of coconut shell charcoal, zeolite, and copper sulfate is 5:2:1.

[0060] The modified bleaching clay was prepared as follows: 70 kg of bleaching clay was dispersed in 120 L of a 2% sodium hydroxide solution and soaked for 2 hours. After washing with water, it was dispersed in 300 L of deionized water, and 12 kg of carbon nanotubes were added. The mixture was stirred for 20 minutes, filtered, and then sprayed with 4.5 L of an aqueous polyurethane solution. The mixture was then dried to obtain the modified bleaching clay. (1 kg of aqueous polyurethane was prepared into a 2 wt% aqueous solution to obtain the aqueous polyurethane solution.)

[0061] The mass ratio of kaolin, carbon nanotubes, and aqueous polyurethane solution is 3:1:0.1.

[0062] Example 5: A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment, which differs from Example 1 in that zeolite is not added during activated carbon pretreatment.

[0063] Example 6: A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment, which differs from Example 1 in that copper sulfate is not added during activated carbon pretreatment.

[0064] Example 7: A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment. The difference from Example 1 is that in the activated carbon pretreatment, the mass ratio of coconut shell charcoal, zeolite, and copper sulfate is 1:6.5:1.

[0065] Example 8: A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment. The difference from Example 1 is that carbon nanotubes are not added in the preparation of modified clay.

[0066] Example 9 A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis treatment of water, the difference from Example 1 is that no aqueous polyurethane solution is added in the preparation of modified clay.

[0067] Example 10: A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment, which differs from Example 1 in that the mass ratio of kaolin, carbon nanotubes, and aqueous polyurethane solution is 1:1:2.

[0068] The performance of a method for inhibiting the formation of 3-chloropropanol ester in peanut oil using two-stage reverse osmosis water treatment obtained in Examples 1-10 was tested. Chloride ion concentration determination: Ion chromatography (referencing GB / T 15454-2020 "Determination of Sodium, Ammonium, Potassium, Magnesium and Calcium Ions in Industrial Circulating Cooling Water - Ion Chromatography Method" and ISO 10304-1:2007 standard) was used to determine the Cl⁻ concentration in the water using a suppressed conductivity detector. The chloride ion content in tap water was 30 mg / L.

[0069] Determination of 3-chloropropanol ester content in oils: According to GB / T 44621-2024 "Grain and Oil Inspection - Determination of 3-chloropropanol fatty acid esters and glycidyl fatty acid esters by GC / MS", the limit of detection (LOD) is 30 μg / kg and the limit of quantitation (LOQ) is 100 μg / kg.

[0070] The test results are shown in Table 1.

[0071] Table 1 Test data for the examples and comparative examples

[0072] The method for inhibiting the formation of 3-chloropropanol esters in peanut oil using a two-stage reverse osmosis process, as described in Example 1 of this application, demonstrates good test results. In Example 1, the activated carbon filter permeate had a chloride ion content of 37 mg / L, the first-stage reverse osmosis permeate had a chloride ion content of 0.45 mg / L, the second-stage reverse osmosis permeate had a chloride ion content of 0.30 mg / L, and the 3-chloropropanol ester content was 0.27 mg / kg. This indicates that by uniformly replacing the key water used in the entire refining process with two-stage reverse osmosis ultra-low chloride pure water, the entire process effectively cuts off the introduction of external chloride ions, achieving source control, reducing the 3-chloropropanol ester content in the finished peanut oil, and improving the safety and quality of edible oil.

[0073] In Examples 3-4, activated carbon was used for pretreatment. As shown in Table 1, the activated carbon filter in Example 3 produced water with a chloride ion content of 12 mg / L, the first-stage reverse osmosis water with a chloride ion content of 0.11 mg / L, and the second-stage reverse osmosis water with a chloride ion content of 0.02 mg / L and a 3-chloropropanol ester content of 0.01 mg / kg. This indicates that the composite activated carbon filter media pretreated by this process significantly improves the ability to remove residual chlorine, organic matter, and trace amounts of chlorine precursors. It can minimize the impurities and initial chlorine load in the raw water, ensuring a stable output of ultra-low chlorine pure water from the two-stage reverse osmosis system. It forms a multi-stage chlorine control barrier at the source, precisely meeting the process requirements for suppressing 3-chloropropanol esters in peanut oil refining.

[0074] In Examples 5-6, no zeolite or copper sulfate was added during activated carbon pretreatment. In Example 7, the mass ratio of coconut shell charcoal, zeolite, and copper sulfate was changed. Table 1 shows that the chloride ion content in the activated carbon filter permeate, the first-stage reverse osmosis permeate, the second-stage reverse osmosis permeate, and the 3-chloropropanol ester content were all significantly increased in Examples 5-6. The contents of all indicators in Example 7 were lower than those in Examples 5-6, but higher than those in Examples 3-4. This indicates that coconut shell charcoal provides a dispersion carrier for CuO, preventing agglomeration; zeolite removes cations, optimizing the microenvironment for CuO chemisorption; and the pores of coconut shell charcoal provide confined space for ion exchange and chemical reactions, improving efficiency, reducing the dechlorination load of the subsequent two-stage reverse osmosis, ensuring stable production of ultra-low chlorine pure water, reducing chloride ion introduction into the peanut oil refining system from the water source, and ultimately achieving the invention's objective of inhibiting 3-chloropropanol ester formation.

[0075] In Examples 8-9, no carbon nanotubes or aqueous polyurethane solution were added during the preparation of modified clay. In Example 10, the mass ratio of clay, carbon nanotubes, and aqueous polyurethane solution was changed. Table 1 shows that the chloride ion content in the activated carbon filter permeate, the chloride ion content in the first-stage reverse osmosis permeate, the chloride ion content in the second-stage reverse osmosis permeate, and the 3-chloropropanol ester content were all significantly increased in Examples 8-9. The contents of all indicators in Example 10 were lower than those in Examples 8-9, but higher than those in Examples 3-4. This indicates that the clay ensures substrate stability, the carbon nanotubes precisely enhance the adsorption of trace chlorine impurities, and the polyurethane provides fixation and prevents detachment, significantly reducing the residual chlorine and organic chlorine precursor content in the raw water, alleviating the treatment pressure of the two-stage reverse osmosis system, and stably producing ultra-low chlorine pure water. This effectively cuts off the external chlorine input in the peanut oil refining process and inhibits the formation of 3-chloropropanol ester in the finished peanut oil.

[0076] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water, characterized in that, Includes the following steps: (1) Tap water is pretreated by passing it through a multi-media filter and an activated carbon filter in sequence to remove suspended solids, residual chlorine and organic matter to obtain pretreated water; (2) The pretreated water obtained in step (1) is desalinated by passing it through a first-stage reverse osmosis membrane module at an operating pressure of 1.0-1.6 MPa to obtain first-stage permeate; (3) The primary permeate obtained in step (2) is subjected to secondary desalination treatment at an operating pressure of 1.0-1.6 MPa through a secondary reverse osmosis membrane module to obtain ultra-low chlorine pure water; (4) Apply the ultra-low chlorine pure water obtained in step (3) to the following steps of peanut oil refining: (a) water for hydration and degumming; (b) water for alkali refining and washing; (c) direct steam for deodorization.

2. The method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water according to claim 1, characterized in that, In step (3), before the secondary reverse osmosis treatment, the primary permeate is degassed to remove carbon dioxide, and then an alkaline solution is added to adjust the pH to 8.0-8.

5.

3. The method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water according to claim 1, characterized in that, In step (4)(a), the amount of ultra-low chlorine pure water added during hydration degumming is 2-5% of the oil weight, the degumming temperature is 60-80℃, and the degumming time is 30-60min.

4. The method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water according to claim 1, characterized in that, In step (4)(b), the amount of ultra-low chlorine pure water added during alkali refining and washing is 10-20% of the oil weight, the washing temperature is 80-95℃, and the number of washing cycles is 1-3.

5. The method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water according to claim 1, characterized in that, In step (4)(c), the deodorization temperature is 200-240℃, the deodorization time is 60-120min, the vacuum degree is 0.2-0.6kPa, and the steam injection amount is 10-20% of the oil weight.

6. The method for inhibiting the formation of 3-chloropropanol esters in peanut oil by using two-stage reverse osmosis to treat water according to claim 1, characterized in that, In step (1), the activated carbon filter is filled with granular activated carbon, and the activated carbon pretreatment includes the following: Coconut shell charcoal, zeolite, and copper sulfate are heated at 300-350℃ for 2-3 hours under nitrogen protection, ground, mixed with modified clay, ground, and sieved to obtain pretreated activated carbon.

7. A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment according to claim 6, characterized in that, The mass ratio of coconut shell charcoal, zeolite, and copper sulfate is 5-6:2-2.5:

1.

8. A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment according to claim 6, characterized in that, The modified clay is prepared as follows: the clay is dispersed in sodium hydroxide solution, soaked for 1-2 hours, washed with water, then dispersed in deionized water, carbon nanotubes are added, stirred for 20-25 minutes, filtered, then sprayed with water-based polyurethane solution, and dried to obtain the modified clay.

9. A method for inhibiting the formation of 3-chloropropanol esters in peanut oil using two-stage reverse osmosis water treatment according to claim 8, characterized in that, The mass ratio of the clay, carbon nanotubes, and aqueous polyurethane solution is 3-5:1:0.1-0.3.

Images