Method for preparing high-bioavailability iron material by extracting acidic phospholipid from soybean oil processing waste liquid
By selectively extracting acidic phospholipids and using in-situ pH-controlled chelation, a highly bioavailable iron material was prepared from soybean oil processing wastewater. This solved the problem of inefficient utilization of acidic phospholipids, achieving low-cost and efficient chelation of iron and promoting soil health.
Patent Information
- Application Number
- CN202511511282.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-22
- Publication Date
- 2026-01-20
AI Technical Summary
Acidic phospholipids in soybean oil refining wastewater are not being utilized efficiently. Existing chelation technologies are costly and require strict pH control, leading to resource waste and environmental pollution.
A three-step method—selective extraction of acidic phospholipids, in-situ pH-controlled chelation, and green purification—was used to extract acidic phospholipids from soybean oil processing wastewater and prepare iron materials with high bioavailability. The natural chelation sites of the acidic phospholipids in the wastewater were used to chelate with Fe²⁺ under low oxygen conditions, avoiding the hydrolysis of iron under traditional neutral pH.
It achieves low-cost, high-efficiency chelation of iron, forming fertilizer enhancers with high bioavailability, promoting soil particle formation and organic carbon accumulation, and reducing resource waste and environmental pressure.
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Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a method for extracting acid phospholipids from soybean oil processing waste liquid to prepare high-bioavailability iron materials, and belongs to the technical field of resource comprehensive utilization and functional materials. BACKGROUND
[0002] Soybean oil refining waste liquid, commonly known as "oil refining wastewater" or "soap foot wastewater", is a kind of high-concentration organic wastewater generated in the process of refining soybean crude oil into edible finished oil. It has the characteristics of complex composition, high pollution load and difficult treatment, and is one of the main pollution sources in the oil industry; if it is not treated and directly discharged into water, it will not only cause the death of aquatic organisms, but also affect agricultural irrigation and drinking water for residents, causing serious environmental pollution.
[0003] The soybean oil refining waste liquid contains a large amount of acid phospholipids (10-30% of dry basis), which is currently used as a low-value feed additive or directly discarded, resulting in not only resource waste but also environmental treatment pressure.
[0004] The acid phospholipid itself is a surfactant with emulsifying, wetting and dispersing properties. Its hydrolysis product (such as lysophospholipid) and further purified single phospholipid component have higher value. The existing phospholipid chelated iron mostly uses purified soybean phospholipid (such as PC, PE), which has high cost and does not utilize the unique chelation sites (-COOH, -PO4H) of the waste liquid acid phospholipid. Moreover, the existing chelation technology needs strict pH control (neutral), and the condition control is strict. Compared with the mainstream chelating agents and purified phospholipids on the market, the cost of obtaining the acid phospholipid in the waste liquid is much lower than that of the purified soybean phospholipid (PC, PE), which provides the possibility for low-cost fertilizer synergist. Therefore, how to efficiently utilize the large amount of acid phospholipid in the soybean oil refining waste liquid has become a difficulty at present. The Journal of Agricultural and Food Chemistry (2018) reports the chelation of neutral phospholipid (PC) with iron, but the problems of waste liquid recovery and acid environment chelation are still not solved. SUMMARY
[0005] In view of the deficiencies of the prior art, the application provides a method for extracting acid phospholipids from soybean oil processing waste liquid to prepare high-bioavailability iron materials.
[0006] The application uses soybean oil processing waste liquid as raw material, and prepares Fe chelation materials through the three-step method of selective extraction of acid phospholipids, in-situ pH regulation and chelation, and green purification. The chelation activity is efficiently utilized, and the complex material containing soybean phospholipid, lecithin, amino acid and Fe is formed. The acid phospholipid in the soybean oil processing waste liquid is developed into a high-value fertilizer synergist material at low cost.
[0007] The application is realized by the technical scheme as follows: A method for extracting acid phospholipid from soybean oil processing waste liquid to prepare high-bioavailability iron material, comprising the following steps: (1) waste liquid pretreatment: removing gum from the soybean oil degumming waste liquid by centrifugation, and enriching acid phospholipid by acid precipitation to obtain acid phospholipid crude extract; (2) iron chelation reaction: mixing the acid phospholipid crude extract with FeSO4 solution, and adding ascorbic acid-citric acid complex antioxidant, directly using the acid phospholipid crude extract of step (1) as a chelating agent without purification, and realizing efficient chelation of Fe²⁺ in a low oxygen environment by using the natural carboxyl / phosphoric acid group to obtain a chelation product; (3) green purification: removing free iron ions by membrane separation of the chelation product, and freeze-drying to obtain a final product.
[0008] According to the application, preferably, in step (1), the centrifugation conditions are 7000-9000 rpm and 10-20 min.
[0009] According to the application, preferably, in step (1), the acid enrichment is adding acid to the soybean oil degumming waste liquid after centrifugation to adjust the pH to 2.0-3.0, preferably, to 2.5.
[0010] According to the application, preferably, in step (2), the concentration of the FeSO4 solution is 0.05-0.3 mol / L.
[0011] Further preferably, in step (2), the concentration of the FeSO4 solution is 0.1 mol / L.
[0012] According to the application, preferably, in step (2), the molar ratio of the acid phospholipid crude extract to the FeSO4 solution is 1: (1-3).
[0013] Further preferably, in step (2), the molar ratio of the acid phospholipid crude extract to the FeSO4 solution is 1:1.5.
[0014] The acid phospholipid crude extract obtained by the application contains phosphatidic acid and lysophospholipid, accounting for ≥30% of the dry weight of the crude extract.
[0015] According to the application, preferably, in step (2), after adding the ascorbic acid-citric acid complex antioxidant, the concentration in the system reaches 0.05-0.2% for ascorbic acid and 0.01-0.1% for citric acid.
[0016] Further preferably, in step (2), after adding the ascorbic acid-citric acid complex antioxidant, the concentration in the system reaches 0.1% for ascorbic acid and 0.05% for citric acid.
[0017] According to the application, preferably, in step (2), the ascorbic acid-citric acid complex antioxidant is a mixture of ascorbic acid and citric acid in a mass ratio of 2:1.
[0018] According to the application, preferably, in step (2), the low-oxygen environment is dissolved oxygen≤0.5 ppm.
[0019] According to the application, preferably, in step (2), the chelation pH is 3-5.
[0020] According to the application, preferably, in step (2), the chelation reaction temperature is 40-60℃, and the reaction is carried out under nitrogen protection for 1-4 hours.
[0021] The application adds ascorbic acid-citric acid complex antioxidant, and high-efficiency chelation (chelation rate≥95%) of Fe²⁺ is realized in a low-oxygen environment (dissolved oxygen).
[0022] According to the application, preferably, in step (3), the membrane separation is carried out by using a membrane with a molecular weight cut-off of 10 kDa.
[0023] The application has the following technical features and advantages: 1. The application first uses waste liquid acid phospholipid (phosphatidic acid, lysophospholipid, etc.) as a chelation carrier, and the cost is reduced by more than 60%, and the chelation ability of the acid phospholipid at low pH is better than that of neutral phospholipid (comparative example 1).
[0024] 2. The application realizes directional combination of the acid phospholipid and iron through in-situ pH regulation (pH 3-5), avoids iron hydrolysis under a traditional neutral pH, and controls the oxidation rate of Fe²⁺ to be less than 5% by a complex antioxidant system.
[0025] 3. The application first uses waste liquid acid phospholipid as a chelation carrier, and the acid phospholipid can still stably chelate at low pH (3-5), and the application conditions are wide.
[0026] 4. The application forms a complex material containing soybean phospholipid, lecithin, amino acid and Fe through green purification and ion chelation of phospholipid in soybean oil processing waste liquid, and it is found through effect test that the complex material has a significant promoting effect on promoting soil particle formation and stability and improving organic carbon content, is a potential organic fertilizer synergistic material, and has industrialization development potential. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 It is a relationship diagram of complex iron content and soil large aggregate quantity in example 1. Figure 2 It is a relationship diagram of complex iron content and soil organic carbon accumulation quantity in example 1. Figure 3 It is a columnar diagram of iron combined state organic carbon content and control group combined state organic carbon content in example 1. DETAILED DESCRIPTION
[0028] The application will be further described in conjunction with the following examples. It should be understood that the examples described herein are intended to illustrate and explain the application, and are not intended to limit the application.
[0029] Example 1 A method for extracting acid phospholipid from soybean oil processing waste liquid to prepare high bioavailability iron material, comprising the following steps: (1) Take 1 L of soybean oil degumming waste liquid, centrifuge at 8000 rpm for 15 min, then adjust the pH to 2.5, precipitate the acid phospholipid, and obtain the acid phospholipid crude extract (containing 35% phosphatidic acid); (2) Mix the acid phospholipid crude extract with 0.1 mol / L FeSO4 solution, the molar ratio of acid phospholipid crude extract to Fe 2+ is 1:1.5, add ascorbic acid-citric acid composite antioxidant, so that the concentration of ascorbic acid is 0.1% and the concentration of citric acid is 0.05%; directly use the acid phospholipid crude extract of step (1) as the chelating agent without purification, utilize its natural carboxyl / phosphoric acid group to realize efficient chelation of Fe²⁺ in a low oxygen environment, react at pH 4.0 under nitrogen protection at 50°C for 2 hours, and obtain the chelation product; (3) Purify the reaction solution through a 10 kDa ultrafiltration membrane, freeze-dry, and obtain a brownish red powder (iron content 12.3%, chelation rate 96.5%).
[0030] Example 2 A method for extracting acid phospholipid from soybean oil processing waste liquid to prepare high bioavailability iron material, comprising the following steps: (1) Take 1 L of soybean oil degumming waste liquid, centrifuge at 8000 rpm for 15 min, then adjust the pH to 2, precipitate the acid phospholipid, and obtain the acid phospholipid crude extract (containing 35% phosphatidic acid); (2) Mix the acid phospholipid crude extract with 0.1 mol / L FeSO4 solution, the molar ratio of acid phospholipid crude extract to Fe 2+ is 1:2, add ascorbic acid-citric acid composite antioxidant, so that the concentration of ascorbic acid is 0.15% and the concentration of citric acid is 0.08%; directly use the acid phospholipid crude extract of step (1) as the chelating agent without purification, utilize its natural carboxyl / phosphoric acid group to realize efficient chelation of Fe²⁺ in a low oxygen environment, react at pH 4.0 under nitrogen protection at 50°C for 2 hours, and obtain the chelation product; (3) Purify the reaction solution through a 10 kDa ultrafiltration membrane, freeze-dry, and obtain a brownish red powder (iron content 12.3%, chelation rate 96.5%).
[0031] Example 3: A method for extracting acid phospholipid from soybean oil processing waste liquid to prepare high bioavailability iron material, comprising the following steps: (1) Take 1 L of soybean oil degumming waste liquid, centrifuge at 8000 rpm for 15 min, then adjust the pH to 2.5, precipitate the acid phospholipid, and obtain the acid phospholipid crude extract (containing 35% phosphatidic acid); (2) Mix the acid phospholipid crude extract with 0.2 mol / L FeSO4 solution, and the molar ratio of the acid phospholipid crude extract to Fe 2+ The molar ratio of the acid phospholipid crude extract to Fe (3) The reaction solution is purified by 10 kDa ultrafiltration membrane, and freeze-dried to obtain a brownish red powder (iron content 12.3%, chelation rate 96.5%).
[0032] Comparative Example 1: Neutral phospholipid chelated iron Under the same conditions, the chelation rate of purified soybean phospholipid (PC≥80%) instead of waste liquid crude extract is only 82% (reduced to 70% at pH>6), which proves the advantage of acid phospholipid at low pH.
[0033] Experimental Example 1 The high bioavailability iron material prepared in Example 1 is applied to soil, and the test results show that the complex iron content and the number of large soil aggregates present a significant positive correlation (p<0.01), as shown in Figure 1 The complex iron content and the cumulative amount of soil organic carbon present a significant positive correlation (p<0.01), as shown in Figure 2 And the iron-bound organic carbon content is significantly higher than that of the control group (without applying high bioavailability iron material), which shows that the present application forms a complex material containing soybean phospholipid, lecithin, amino acids and Fe through green purification and ion chelation of phospholipid in soybean oil processing waste liquid, which has a significant promoting effect on promoting soil particle formation and stability and improving organic carbon content, is a potential organic fertilizer synergistic material, and has industrialization development potential.
Claims
1. A method for preparing high bioavailability iron material from acid phospholipid extracted from soybean oil processing waste liquid, comprising the following steps: (1) waste liquid pretreatment: removing gum by centrifugation of soybean oil degumming waste liquid, and enriching acid phospholipid by acid precipitation to obtain acid phospholipid crude extract; (2) iron chelation reaction: mixing the acid phospholipid crude extract with FeSO4 solution, and adding ascorbic acid-citric acid complex antioxidant, directly using the acid phospholipid crude extract of step (1) as chelator without purification, and realizing efficient chelation of Fe²⁺ under low oxygen environment by using its natural carboxyl / phosphoric acid group to obtain chelation product; (3) green purification: removing free iron ions by membrane separation of the chelation product, and freeze-drying to obtain the final product.
2. The method of claim 1, wherein, In step (1), the centrifugation conditions are 7000-9000 rpm and 10-20 min.
3. The method of claim 1, wherein, In step (1), the acid precipitation enrichment is adding acid to the soybean oil degumming waste liquid after centrifugation to adjust the pH to 2.0-3.
0.
4. The method of claim 1, wherein, In step (2), the concentration of FeSO4 solution is 0.05-0.3 mol / L.
5. The method of claim 1, wherein, In step (2), the molar ratio of acid phospholipid crude extract to FeSO4 solution is 1: (1-3), and further preferably, the molar ratio of acid phospholipid crude extract to FeSO4 solution in step (2) is 1:1.
5.
6. The method of claim 1, wherein, In step (2), the concentration of ascorbic acid-citric acid complex antioxidant after addition is 0.05-0.2% for ascorbic acid and 0.01-0.1% for citric acid.
7. The method of claim 1, wherein, In step (2), the ascorbic acid-citric acid complex antioxidant is a mixture of ascorbic acid and citric acid in a mass ratio of 2:
1.
8. The method of claim 1, wherein, In step (2), the low oxygen environment is dissolved oxygen ≤0.5 ppm.
9. The method of claim 1, wherein, The chelation pH is 3-5, the chelation reaction temperature is 40-60℃, and the reaction is carried out under nitrogen protection for 1-4 hours.
10. The method of claim 1, wherein, In step (3), the membrane separation is using a membrane with a molecular weight cut-off of 10 kDa.