A method for preparing high-strontium mineral water with improved strontium absorption rate and application thereof

Abstract

The application relates to a high-strontium mineral water preparation method for improving strontium absorption and application of the same. The method comprises raw water input, pretreatment and purification, two-stage nanofiltration grading purification, strontium concentrate liquid and low-mineral dialysis, constant-temperature targeted chelation reaction, chelated strontium mother liquor, sterile blending, calcium-strontium ratio precise control, improvement of strontium absorption and utilization, double strategies of calcium-strontium ratio lock control and ion removal, solution of competition of calcium and magnesium ions on strontium absorption from the root, mild reaction in the whole process, no high temperature and high pressure, no introduction of harmful by-products, all raw materials meeting national food safety standards, no taste difference, no peculiar smell and no astringency.

Description

Technical Field

[0001] This invention belongs to the field of drinking water processing technology, and in particular relates to a method for preparing high-strontium mineral water with improved strontium absorption rate and its application. Background Technology

[0002] Strontium is an essential trace element for the human body, playing a vital role in bone development, teeth mineralization, and cardiovascular health. Natural mineral water is an ideal source of strontium, but strontium in conventional mineral water primarily exists as inorganic ions, which have low absorption and utilization rates in the human intestine. Studies have shown that divalent ions such as calcium and magnesium in the intestine compete with strontium ions for the same absorption channels (such as the TRPV6 channel), further reducing strontium absorption.

[0003] In existing technologies, the following two approaches are commonly used to improve the absorption rate of strontium: one is to directly add inorganic strontium salts to mineral water, but this method fails to solve the problem of calcium-magnesium competition and is prone to producing a bitter taste; the other is to convert inorganic strontium into amino acid chelated strontium through chelation reaction, but this process requires the addition of exogenous chelating agents, which poses a risk of introducing harmful byproducts, and the high temperature and high pressure reaction conditions will destroy the natural properties of mineral water.

[0004] Therefore, there is an urgent need to develop a mineral water preparation method that can effectively solve the calcium-magnesium competition problem and significantly improve strontium absorption rate without adding exogenous substances or changing the natural properties of mineral water. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of poor quality of conventional drinking water, and to propose a method for preparing high-strontium mineral water with improved strontium absorption rate and its application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing high-strontium mineral water with improved strontium absorption rate includes the following steps: S1. Pretreatment and purification: The raw water is subjected to multi-media filtration, activated carbon filtration and security filtration; S2. Selective enrichment of strontium by ion exchange: The pretreated water is passed through a strontium selective ion exchange resin to adsorb strontium ions and then eluted to obtain a strontium concentrate, while also obtaining low-strontium treated water. S3. Nanofiltration to remove calcium ions: The low-strontium treated water obtained in step 2 is passed through a nanofiltration membrane to remove calcium ions and obtain low-calcium treated water. S4. Electric field cutting of molecular clusters: The strontium concentrate obtained in step S2 is subjected to an electric field to destroy the water molecule cluster structure and obtain an activated strontium concentrate. S5. Ion exchange introduction of strontium: The activated strontium concentrate obtained in step S4 is mixed with the low-calcium treated water obtained in step S3, and then strontium ions are uniformly introduced through a cation exchange resin to obtain the finished base solution. S6. Post-processing: The finished base liquid is subjected to aseptic precision filtration, pH locking, and aseptic cold filling.

[0007] Preferably, the strontium content of the raw water in step S1 is 0.15-0.30 mg / L, and the pH is 7.0-8.0.

[0008] Preferably, the pretreatment purification in step S1 includes multi-media filtration, activated carbon filtration and 5m security filtration in sequence.

[0009] Preferably, in step S2, the strontium selective ion exchange resin is an iminodiacetic acid type chelating resin, the elution is performed using food-grade sodium chloride solution, and the strontium content in the resulting strontium concentrate is 2.0-3.0 mg / L.

[0010] Preferably, in step S2, the strontium selective ion exchange resin is an iminodiacetic acid type chelating resin, the elution is performed using food-grade sodium chloride solution, and the strontium content in the resulting strontium concentrate is 2.0-3.0 mg / L.

[0011] Preferably, in step S4, the electric field processing uses a DC pulsed electric field with a field strength of 515 V / cm and a processing time of 1030 seconds.

[0012] Preferably, the cation exchange resin in step S5 is a weakly acidic cation exchange resin, and the calcium-strontium ratio in the finished base solution after mixing is 4:1.

[0013] Preferably, the aseptic precision filtration in step S6 includes a 1m filtration and a 0.22m terminal aseptic filtration, with the pH locked at 7.2-7.5.

[0014] An application of the above-mentioned method for preparing high-strontium mineral water with improved strontium absorption rate is disclosed. The high-strontium mineral water prepared by the method has a strontium content of 1.5-2.5 mg / L, a calcium content of 2.0 mg / L, and a calcium-strontium ratio of 4:1, and is suitable for drinking by middle-aged and elderly people, pregnant and postpartum women, and teenagers.

[0015] In summary, the technical effects and advantages of this invention are as follows: 1. This invention selectively enriches strontium through ion exchange, achieving initial separation of strontium from calcium and magnesium. Subsequently, it uses nanofiltration to retain calcium ions, eliminating the competitive interference of calcium ions on strontium absorption channels. This avoids the shortcomings of existing technologies that cannot solve the competition problem by directly adding inorganic strontium salts. By employing electric field cutting molecular cluster technology, without adding any exogenous chelating agents, it destroys the water molecule cluster structure through physical field action, reducing the hydration radius of strontium ions, improving their mobility and diffusion, and significantly enhancing the bioavailability of strontium. This avoids the problems of the prior art, such as the need to add exogenous substances for chelation reactions, the risk of harmful byproducts, and the damage to the natural properties of mineral water caused by high temperature and high pressure.

[0016] 2. The present invention introduces strontium through ion exchange, thereby achieving uniform distribution and stable morphology of strontium ions in low-calcium treated water, ensuring that the finished product remains free of precipitation and turbidity during long-term storage, thus preserving the natural properties of mineral water. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the preparation method for improving strontium absorption in mineral water according to the present invention. Detailed Implementation

[0018] The technical solutions in the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, and not all embodiments.

[0019] like Figure 1 As shown, it includes the following steps: S1, Pretreatment and purification Natural mineral water was selected as the raw water. Testing revealed that the raw water contained 0.22 mg / L of strontium, 32.5 mg / L of calcium, 8.6 mg / L of magnesium, had a pH of 7.3, and a total dissolved solids of 210 mg / L.

[0020] The raw water is pre-treated and purified by passing it sequentially through a multi-media filter, an activated carbon filter, and a 5m security filter.

[0021] The multi-media filter, filled with quartz sand and anthracite, removes suspended solids, colloids, and some iron and manganese oxides from the water through interception, sedimentation, and adsorption. The activated carbon filter utilizes the large specific surface area and adsorption capacity of activated carbon to remove residual chlorine, organic matter, and some odor substances from the water. The security filter acts as a pre-filter for the membrane system, intercepting particles larger than 5 μm to prevent clogging and damage to subsequent membrane modules. After pretreatment, the effluent turbidity is 0.2 NTU, residual chlorine is 0.05 mg / L, and the SDI (Spectrum Difference Indication) is 3.0, providing stable influent water quality for subsequent ion exchange and nanofiltration processes.

[0022] S2, ion exchange selective enrichment of strontium The pretreated water obtained in step S1 was passed through an ion exchange column packed with iminodiacetic acid chelating resin. The pH of the influent was controlled at 6.5-0.2, the temperature at 252℃, and the water was passed through the resin column at a flow rate of 5 BV / h for adsorption. After the resin was saturated, it was eluted with a 2.0% (w / v) food-grade sodium chloride solution at a flow rate of 2 BV / h. The first 0.5-1.5 BV of the eluent was collected as the strontium concentrate.

[0023] Iminodiacetic acid-type chelating resins contain N(CH2COOH)2 functional groups, which chelate divalent metal ions under weakly acidic conditions (pH 6.0-7.0). Due to Sr + The coordination stability with resin functional groups is higher than that with Ca + and Mg + Resin for Sr + The selective adsorption coefficient is approximately Ca + 58 times.

[0024] During the adsorption phase, Sr in the water + It is preferentially captured by the resin, while most of the Ca... + Mg + It then flows through the water, achieving the initial separation of strontium from calcium and magnesium. During the elution stage, high concentrations of Na... + Sr on the replacement resin + The strontium ions are released back into the eluent to form a strontium concentrate.

[0025] Testing revealed that the obtained strontium concentrate contained 2.8 mg / L of strontium, 3.5 mg / L of calcium, 1.2 mg / L of magnesium, and had a pH of 6.7. The ion-exchange effluent contained 0.02 mg / L of strontium, 29.8 mg / L of calcium, and 8.2 mg / L of magnesium. This step achieved approximately 13-fold concentration of strontium, while simultaneously reducing the calcium-to-strontium ratio from 148:1 in the original water to 1.25:1.

[0026] S3, Nanofiltration retains calcium ions The ion-exchange effluent obtained in step S2 is passed into a spiral-wound polyamide composite nanofiltration membrane module. The operating pressure is 0.8 MPa, the temperature is 252 °C, and the system recovery rate is 75%.

[0027] Nanofiltration membranes are pressure-driven membranes that fall between reverse osmosis and ultrafiltration. They have a pore size of approximately 12 nm and a negatively charged surface. Their ion retention mechanisms include the sieving effect and the Donnan effect. The sieving effect refers to the retention of ions with diameters larger than the membrane pore size; the Donnan effect refers to the electrostatic attraction of cations and electrostatic repulsion of anions by the negative charge on the membrane surface. Simultaneously, to maintain electroneutrality, divalent cations (such as Ca²⁺) are retained. + Mg +The retention rate of ) is significantly higher than that of monovalent cations (such as Na+). + K + In this step, the nanofiltration membrane is used for Ca... + The rejection rate is 90%, while water molecules and monovalent ions can pass through freely.

[0028] After nanofiltration treatment, the permeate was collected as low-calcium treated water. Testing revealed that the calcium content in the low-calcium treated water was 1.6 mg / L, the magnesium content was 0.6 mg / L, strontium was undetectable, and the total dissolved solids were 42 mg / L. This step reduced the calcium ion concentration from 29.8 mg / L to 1.6 mg / L, achieving a removal rate of 94.6%, thus eliminating the competitive interference of calcium ions on subsequent strontium absorption at the source.

[0029] S4, electric field cuts molecular groups The strontium concentrate obtained in step S2 is transported to a DC pulse electric field processing device. The device adopts a parallel plate electrode structure with a plate spacing of 5 cm. The electric field strength is set to 12 V / cm, the pulse frequency is 50 Hz, the duty cycle is 60%, and the processing time is 20 seconds.

[0030] Water molecules form clusters of varying sizes through hydrogen bonds. In their natural state, water molecules... 17 O-NMR peak widths are typically between 100 and 150 Hz. When an external electric field is applied, water molecules, being polar molecules, undergo orientational polarization under the influence of the field, disrupting the hydrogen bond network. Large molecular clusters dissociate into smaller clusters or even individual water molecules. Strontium ions exist in water as hydrated ions, and their hydration radius depends on the arrangement of the surrounding water molecules. When the size of the water molecule clusters decreases, the hydration radius of the strontium ions also decreases, significantly increasing their mobility and diffusivity, making them more easily absorbed by the intestines.

[0031] After being treated with an electric field, the strontium concentrate... 17 The full width at half maximum (FWHM) of the O-NMR decreased from 125 Hz to 92 Hz, indicating a significant reduction in water molecule clusters; the estimated hydration radius of strontium ions decreased from 0.42 nm to 0.31 nm, and the diffusion coefficient increased by approximately 35%.

[0032] S5, ion exchange introduction of strontium The low-calcium treated water obtained in step S3 and the strontium concentrate obtained after electric field activation in step S4 are premixed at a volume ratio of 10:1, and then passed through an ion exchange column packed with weakly acidic cation exchange resin at a flow rate of 4 BV / h, controlling the pH of the influent to be 7.2-0.2.

[0033] Weakly acidic cation exchange resins contain COOH functional groups and can undergo ion exchange reactions under weakly alkaline conditions (pH 7.0-7.5): 2RCOOH + Sr +(RCOO)2Sr + 2H + .

[0034] Compared with direct stirring and mixing, the process of ion exchange is slow, which avoids the supersaturation caused by excessively high local concentrations and prevents the formation of strontium salt precipitation; secondly, the resin column, as a mixing medium, can achieve uniform distribution of strontium ions in low-calcium treated water; thirdly, after the ion exchange reaction reaches equilibrium, strontium ions exist in water in a stable hydrated ion form and are not prone to form transformation.

[0035] After ion exchange treatment, the effluent was collected as the base solution for the finished product. Testing revealed that the base solution contained 2.05 mg / L of strontium, 1.6 mg / L of calcium, and 0.6 mg / L of magnesium, with a calcium-to-strontium ratio of 0.78:1 and a pH of 7.3. Speciation analysis showed that strontium in the finished product existed in the form of free hydrated ions, accounting for 98%, with no precipitated or colloidal strontium.

[0036] S6, Post-processing The finished base liquid obtained in step S5 is subjected to aseptic precision filtration through a 1m pre-filter and a 0.22m terminal aseptic filter at a filtration pressure of 0.2 MPa.

[0037] The 1m pre-filtration removes any particulate matter and some microorganisms that may be present, protecting the terminal filter cartridge; the 0.22m terminal aseptic filter effectively traps all bacteria and most viruses, ensuring the product's microbiological safety.

[0038] Adjust the pH of the filtrate to 7.3 using food-grade sodium bicarbonate solution. Mineral water is most stable in a slightly alkaline environment (pH 7.2-7.5), which can prevent strontium ions from forming precipitates with carbonate, sulfate, etc., while maintaining a sweet taste.

[0039] In a Class 100 clean environment, the pH-adjusted liquid is aseptically cold-filled and capped at a filling temperature of 25°C. Cold filling avoids the damage to the natural components and taste of mineral water caused by high-temperature sterilization, and the aseptic environment ensures the product's microbiological safety throughout its shelf life.

[0040] The finished product after filling was tested for physicochemical, microbiological, and heavy metal indicators. The results showed that the strontium content was 2.05 mg / L, the calcium content was 1.6 mg / L, the calcium-strontium ratio was 0.78:1, the pH was 7.3, and the total dissolved solids were 48 mg / L. The total bacterial count was <10 CFU / mL, and coliform bacteria and Pseudomonas aeruginosa were not detected. Lead, arsenic, cadmium, and mercury were all not detected (<0.001 mg / L).

[0041] The finished product, stored at 25℃ in the dark for 12 months, showed no precipitation or turbidity, and the strontium content decreased by 3%. Example 2 The difference between this example and Example 1 is that the raw water quality is different.

[0042] In this embodiment, the raw water contained 0.16 mg / L of strontium, 28.3 mg / L of calcium, 7.2 mg / L of magnesium, had a pH of 7.1, and a total dissolved solids of 185 mg / L.

[0043] In step S2, the eluent is collected at a rate of 0.5-1.5 BV, and the strontium content in the resulting strontium concentrate is 2.2 mg / L. In step S3, the operating pressure is 0.75 MPa, and the calcium content in the resulting low-calcium treated water is 1.4 mg / L. In step S4, the electric field strength is 10 V / cm, and the treatment time is 25 seconds. In step S5, the volume ratio of the strontium concentrate to the low-calcium treated water is 1:12.

[0044] The finished product was tested and found to contain 1.82 mg / L of strontium, 1.4 mg / L of calcium, with a calcium-to-strontium ratio of 0.77:1 and a pH of 7.2. The microbiological indicators met the standards, and the finished product showed no precipitation or turbidity after being stored at 25°C in the dark for 12 months.

[0045] Example 3 The difference between this embodiment and Embodiment 1 is that the electric field cutting parameters are different.

[0046] In step S4 of this embodiment, the electric field strength is set to 15 V / cm, the pulse frequency to 100 Hz, the duty cycle to 70%, and the processing time to 15 seconds.

[0047] Testing revealed that the finished product contained 2.03 mg / L of strontium, 1.6 mg / L of calcium, a calcium-to-strontium ratio of 0.79:1, and a pH of 7.3. After electric field treatment, the strontium concentrate... 17 The half-maximum width of the O-NMR decreased to 88 Hz, the hydration radius of strontium ions further decreased, and the diffusion coefficient increased by about 42%. The finished product showed no precipitation or turbidity after being stored at 25°C in the dark for 12 months, and the strontium absorption rate was slightly improved compared to Example 1.

[0048] Comparative Example 1 The difference between this comparative example and Example 1 is that step S2, ion exchange for selective enrichment of strontium, is omitted.

[0049] The process flow of this comparative example is as follows: raw water pretreatment, nanofiltration concentration, electric field cutting, and nanofiltration permeate mixing and post-treatment.

[0050] Testing revealed that the strontium concentration in the nanofiltration concentrate was 0.45 mg / L, and the calcium concentration was 58 mg / L. The final product, after mixing, contained 0.22 mg / L of strontium and 12.5 mg / L of calcium, resulting in a calcium-to-strontium ratio of 56.8:1. The final product had a slightly astringent taste, and the calcium-to-strontium ratio far exceeded the target value (4:1), failing to effectively supplement strontium.

[0051] Comparative Example 2 The difference between this comparative example and Example 1 is that step S3, nanofiltration to retain calcium ions, is omitted.

[0052] The process flow of this comparative example is as follows: raw water pretreatment, ion exchange enrichment of strontium-strontium concentrate, mixing with ion exchange effluent, electric field cutting, ion exchange introduction, and post-treatment.

[0053] Testing revealed that the finished product contained 2.05 mg / L of strontium and 8.6 mg / L of calcium, with a calcium-to-strontium ratio of 4.2:1. After six months of storage, a trace amount of precipitation appeared, which was identified as calcium carbonate crystals. The product had a slightly heavier taste, and the calcium-to-strontium ratio was slightly higher than the target value.

[0054] Comparative Example 3 The difference between this comparative example and Example 1 is that step S4, electric field cutting of molecular clusters, is omitted.

[0055] The process flow of this comparative example is as follows: raw water pretreatment, ion exchange enrichment, strontium nanofiltration retention, calcium and strontium concentrate, direct mixing, ion exchange introduction, and post-treatment.

[0056] Testing revealed that the finished product contained 2.02 mg / L of strontium and 1.6 mg / L of calcium, with a calcium-to-strontium ratio of 0.79:1. After 9 months of storage, trace amounts of precipitation appeared in the finished product. In vitro simulated intestinal absorption experiments showed that the strontium absorption rate was 18% lower than in Example 1.

[0057] Comparative Example 4 The difference between this comparative example and Example 1 is that ion exchange is not used in step S5; instead, direct stirring and mixing are used.

[0058] The process flow of this comparative example is as follows: raw water pretreatment, ion exchange enrichment, strontium nanofiltration, calcium interception, electric field cutting, direct stirring, mixing, and post-treatment.

[0059] Testing revealed that the finished product contained 2.08 mg / L of strontium and 1.6 mg / L of calcium, with a calcium-to-strontium ratio of 0.77:1. After three months of storage, the finished product developed a distinct white flocculent precipitate, which, upon analysis, was found to be strontium carbonate and a small amount of calcium carbonate. The taste deteriorated, becoming astringent.

[0060] The finished products of Example 13 and Comparative Example 14 were tested for various indicators, and the results are summarized in Table 1.

[0061] Table 1 Comparison of test results for each embodiment and comparative example project Strontium content (mg / L) Calcium content (mg / L) Calcium-Strontium ratio 12-month stability Increased Strontium Absorption* Example 1 2.05 1.6 0.78:1 No sediment 42% Example 2 1.82 1.4 0.77:1 No sediment 38% Example 3 2.03 1.6 0.79:1 No sediment 45% Comparative Example 1 0.22 12.5 56.8:1 There is sediment Comparative Example 2 2.05 8.6 4.2:1 6 months of settling 12% Comparative Example 3 2.02 1.6 0.79:1 9 months of accumulation 24% Comparative Example 4 2.08 1.6 0.77:1 3 months of settling 18% Table 1 As shown in Table 1, the high-strontium mineral water prepared in Example 13 of this invention has a calcium-strontium ratio controlled within the range of 4:1. The finished product has no precipitation or turbidity during the 12-month storage period, and the strontium absorption rate is 38%-45% higher than that of ordinary commercially available strontium mineral water.

[0062] Comparative Examples 1 and 4 all exhibited varying degrees of defects: Comparative Example 1 failed to achieve effective enrichment of strontium; Comparative Example 2 showed incomplete removal of calcium ions, resulting in substandard stability and calcium-strontium ratio; Comparative Example 3 exhibited decreased long-term stability and absorption rate; and Comparative Example 4 demonstrated extremely poor storage stability. None of the aforementioned comparative examples simultaneously met the comprehensive requirements for strontium content, calcium-strontium ratio, stability, and absorption rate.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing high-strontium mineral water with improved strontium absorption rate, characterized in that, Includes the following steps: S1. Pretreatment and purification: The raw water is subjected to multi-media filtration, activated carbon filtration and security filtration; S2. Selective enrichment of strontium by ion exchange: The pretreated water is passed through a strontium selective ion exchange resin to adsorb strontium ions and then eluted to obtain a strontium concentrate, while also obtaining low-strontium treated water. S3. Nanofiltration to remove calcium ions: The low-strontium treated water obtained in step 2 is passed through a nanofiltration membrane to remove calcium ions and obtain low-calcium treated water. S4. Electric field cutting of molecular clusters: The strontium concentrate obtained in step S2 is subjected to an electric field to destroy the water molecule cluster structure and obtain an activated strontium concentrate. S5. Ion exchange introduction of strontium: The activated strontium concentrate obtained in step S4 is mixed with the low-calcium treated water obtained in step S3, and then strontium ions are uniformly introduced through a cation exchange resin to obtain the finished base solution. S6. Post-processing: The finished base liquid is subjected to aseptic precision filtration, pH locking, and aseptic cold filling.

2. The method for preparing high-strontium mineral water with improved strontium absorption rate according to claim 1, characterized in that: In step S1, the strontium content of the raw water is 0.15-0.30 mg / L, and the pH is 7.0-8.

0.

3. The method for preparing high-strontium mineral water with improved strontium absorption rate according to claim 1, characterized in that: The pretreatment purification in step S1 includes multi-media filtration, activated carbon filtration, and 5m security filtration in sequence.

4. The method for preparing high-strontium mineral water with improved strontium absorption rate according to claim 1, characterized in that: In step S2, the strontium selective ion exchange resin is an iminodiacetic acid type chelating resin, and the elution is performed using food-grade sodium chloride solution. The strontium content in the resulting strontium concentrate is 2.0-3.0 mg / L.

5. The method for preparing high-strontium mineral water with improved strontium absorption rate according to claim 1, characterized in that: In step S3, the nanofiltration membrane has a calcium ion rejection rate of 90%, and the calcium content in the resulting low-calcium treated water is 2.0 mg / L.

6. The method for preparing high-strontium mineral water with improved strontium absorption rate according to claim 1, characterized in that: In step S4, the electric field processing uses a DC pulsed electric field with a field strength of 515 V / cm and a processing time of 1030 seconds.

7. The method for preparing high-strontium mineral water with improved strontium absorption rate according to claim 1, characterized in that: In step S5, the cation exchange resin is a weakly acidic cation exchange resin, and the calcium-strontium ratio in the finished base solution after mixing is 4:

1.

8. The method for preparing high-strontium mineral water with improved strontium absorption rate according to claim 1, characterized in that: The aseptic precision filtration in step S6 includes a 1 μm filtration and a 0.22 μm terminal aseptic filtration, with the pH locked at 7.2-7.

5.

9. An application of the method for preparing high-strontium mineral water with enhanced strontium absorption rate as described in any one of claims 1-8, characterized in that, The high-strontium mineral water prepared by the method has a strontium content of 1.5-2.5 mg / L, a calcium content of 2.0 mg / L, and a calcium-strontium ratio of 4:1, making it suitable for drinking by middle-aged and elderly people, pregnant and postpartum women, and teenagers.

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