Method for separating sorbitol solution and maltitol solution from polyol solution
Through nanofiltration separation technology, the problems of complex equipment, high cost and low efficiency in polyol solution separation are solved, and efficient production of high-purity sorbitol liquid and maltitol liquid is achieved, reducing production costs and improving market competitiveness.
Patent Information
- Application Number
- CN202510396525.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-07-04
Smart Images
Figure CN120247658A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of sugar alcohol preparation, and particularly relates to a method for separating sorbitol solution and maltitol solution from a polyol solution. Background Art
[0002] Due to the large fluctuations in the contents of maltitol and sorbitol in the polyol solution raw materials, traditional separation techniques, especially chromatographic separation, are highly sensitive to the component contents of the raw materials. Chromatographic separation relies on the interaction between the stationary phase and the mobile phase, and fluctuations in the raw material contents may change these interactions, thereby affecting the discharge time and position of the product, making the process require frequent re-optimization and testing.
[0003] The currently adopted separation techniques, such as chromatographic separation, not only require expensive equipment investment but also involve complex operation steps, and these factors together drive up the production cost. The chromatographic separation system requires the support of a complete set of chromatographic equipment, and the cost of chromatographic resin is particularly high, further increasing the separation cost of polyols.
[0004] Polyols contain abundant maltitol and sorbitol, and these components have high market value. However, due to the relatively low selling price of polyols and their limited application scope, the overall product value has not been fully realized.
[0005] The existing chromatographic separation techniques for polyol solutions have the following disadvantages: High complexity: Chromatographic separation techniques require a set of chromatographic equipment, which not only increases the complexity of the system but is also not easy to operate; High cost: Using chromatographic separation techniques to separate and purify the residual liquid requires a large investment, especially the costs in equipment and operation are high; Low efficiency: In some cases, such as in the method of obtaining sorbitol solution and liquid polyol by decolorizing and filtering the fermentation broth and then performing membrane separation, the time for saccharification and fermentation is very long, affecting the efficiency; Product purity problem: The existing techniques may not always ensure high product purity, especially other impurities may be mixed in during the separation process. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a method for separating sorbitol solution and maltitol solution from a polyol solution, enhancing the raw material adaptability, reducing the production expenses, and increasing the market value of the product.
[0007] The present invention is realized as follows. A method for separating sorbitol solution and maltitol solution from a polyol solution is provided, including the following steps: Step 1: Select a polyol solution with a maltitol mass content of 30.00% - 40.00% and a sorbitol mass content of 30.00% - 40.00%, and dilute the polyol solution to a raw material with a refractive index of 19.7% - 26.0%. Step 2: Add activated carbon with a mass ratio of 0.1% - 1% to the raw material, perform decolorization treatment at 70°C for 1 h, and then perform vacuum filtration treatment. Step 3: Select an ultrafiltration membrane with a relative molecular mass (MmCO) of 3.5×10^3 to perform ultrafiltration treatment on the raw material after filtration, and obtain a dilute solution and a concentrated solution respectively. Sorbitol and maltitol pass through the ultrafiltration membrane and enter the dilute solution, while macromolecular fusel alcohols enter the concentrated solution. Step 4: Use a nanofiltration membrane with a molecular weight of 500 - 1000 to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane. The nanofiltration pressure is 30 bar, and the nanofiltration temperature is 45°C, to obtain the required sorbitol solution and maltitol solution respectively; in the sorbitol solution, the mass content of sorbitol is 76.17%, and in the maltitol solution, the mass content of maltitol is 55.07%.
[0008] Compared with the prior art, the method for separating sorbitol solution and maltitol solution from polyol solution of the present invention has the following characteristics: 1. High separation efficiency: The present invention adopts nanofiltration separation technology, and by selectively retaining maltitol and sorbitol with different molecular weights in the polyol, high-efficiency separation of maltitol and sorbitol is achieved.
[0009] 2. High product purity: The application of nanofiltration separation technology enables the present invention to obtain sorbitol solution and maltitol solution with high purity. Due to the precise retention characteristics of the nanofiltration membrane, maltitol and sorbitol in the raw material can be effectively separated, thereby improving the purity of the product.
[0010] 3. Cost reduction: Compared with traditional technologies such as chromatographic separation, nanofiltration separation technology does not require the use of a large amount of chemical reagents and expensive chromatographic columns, thus reducing the production cost. In addition, the service life of the nanofiltration membrane is long and the maintenance is simple, further reducing the operating cost.
[0011] 4. Environmentally friendly: The nanofiltration separation technology adopted by the present invention is a physical separation method and does not require the use of harmful chemical solvents, so it has less impact on the environment.
[0012] 5. Simple operation: The nanofiltration separation technology of the present invention is simple to operate and easy to control, and does not require complex operation skills and professional knowledge, which makes the production process more flexible, easy to realize automatic control, and improves the production efficiency.
[0013] 6. Flexibility and adaptability: The nanofiltration separation technology can adapt to polyol raw materials with different concentrations and compositions, showing good adaptability and flexibility. This means that the present invention can be applied to a variety of different production environments and raw material conditions, with broad application prospects.
[0014] 7. Improving market competitiveness: Since the present invention can produce high-purity sorbitol solution and maltitol solution products from polyol solutions with relatively low value, this will improve the market competitiveness of the products and bring more economic benefits to the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a schematic flow chart of the method for separating sorbitol solution and maltitol solution from polyol solution according to the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0016] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0017] Please refer to Figure 1 As shown, it is a preferred embodiment of the method for separating sorbitol solution and maltitol solution from polyol solution according to the present invention, and the direction of the process is shown by the arrows in the figure. The method includes the following steps: Step 1: Select a polyol solution with a maltitol mass content of 30.00% - 40.00% and a sorbitol mass content of 30.00% - 40.00%, and dilute the polyol solution to a raw material with a refractive index of 19.7% - 26.0%.
[0018] Step 2: Add activated carbon with a mass ratio of 0.1% - 1% to the raw material, perform a decolorization treatment at 70°C for 1 hour, and then perform a vacuum filtration treatment to remove the activated carbon and macromolecular impurities, so as to improve the service life and separation efficiency of the nanofiltration membrane.
[0019] Step 3: Select an ultrafiltration membrane with a relative molecular mass (MmCO) of 3.5×10^3 to perform ultrafiltration treatment on the raw material after the filtration treatment, and obtain a dilute solution and a concentrated solution respectively. Sorbitol and maltitol pass through the ultrafiltration membrane and enter the dilute solution, while macromolecular fusel alcohols enter the concentrated solution.
[0020] Step 4: Use a nanofiltration membrane with a molecular weight of 500 - 1000 to perform nanofiltration separation treatment on the dilute solution treated by the ultrafiltration membrane. The nanofiltration pressure is 30 bar and the nanofiltration temperature is 45°C to obtain the required sorbitol solution and maltitol solution respectively; in the sorbitol solution, the sorbitol mass content is 76.17%, and in the maltitol solution, the maltitol mass content is 55.07%.
[0021] The method for separating sorbitol solution and maltitol solution from polyol solution of the present invention will be further described below through specific embodiments.
[0022] Example 1
[0023] The first embodiment of the method for separating sorbitol solution and maltitol solution from polyol solution of the present invention includes the following steps: Step 11: Take 15 L of polyol solution with a refractive index of 40%, add 17.3 L of high-purity water, and dilute it into a raw material with a refractive index of 20.1%. In the polyol solution, the mass content of maltitol is 30.14%, and the mass content of sorbitol is 32.01%.
[0024] Step 12: Add 69 g of activated carbon to the raw material, perform decolorization treatment at an operating temperature of 70 °C and keep warm for 1 h, and then perform vacuum filtration to obtain a raw material with a light transmittance (420 nm, 10 cm colorimetric cell) of 87%.
[0025] Step 13: Ultrafilter the raw material after filtration treatment with an ultrafiltration membrane with a relative molecular mass of 3.5×10^3 at an operating pressure of 10 bar to obtain 27.2 L of dilute solution with a refractive index of 17.6% and 4.9 L of concentrated solution with a refractive index of 32.7%. In the dilute solution, the mass content of sorbitol is 42.14%, and the mass content of maltitol is 38.23%.
[0026] Step 14: Use a nanofiltration membrane with a molecular weight cut-off of 1000 to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane at an operating pressure of 30 bar and an operating temperature of 45 °C to obtain 19.5 L of sorbitol solution with a refractive index of 9.0% and 7.7 L of maltitol solution with a refractive index of 37.1% as required. In the sorbitol solution, the mass content of sorbitol is 76.17%, and the mass content of maltitol is 5.14%. In the maltitol solution, the mass content of maltitol is 56.35%, and the mass content of sorbitol is 23.54%.
[0027] Example 2
[0028] The second embodiment of the method for separating sorbitol solution and maltitol solution from polyol solution of the present invention includes the following steps: Step 21: Take 15 L of polyol solution with a refractive index of 35%, add 13.9 L of high-purity water, and dilute it into a raw material with a refractive index of 19.7%. In the polyol solution, the mass content of maltitol is 33.23%, and the mass content of sorbitol is 30.17%.
[0029] Step 22: Add 186 g of activated carbon to the raw materials, perform decolorization treatment at an operating temperature of 70 °C for 1 h, and then carry out vacuum filtration to obtain raw materials with a light transmittance (420 nm, 10 cm colorimetric cell) of 90%.
[0030] Step 23: Ultrafilter the raw materials after filtration treatment using an ultrafiltration membrane with a molecular weight cut-off of 3.5×10^3 at an operating pressure of 10 bar to obtain 24.7 L of dilute solution with a refractive index of 17.0% and 4.2 L of concentrated solution with a refractive index of 34.4%. In the dilute solution, the mass content of sorbitol is 40.65% and the mass content of maltitol is 43.32%.
[0031] Step 24: Use an 800 molecular weight nanofiltration membrane to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane at an operating pressure of 30 bar and an operating temperature of 45 °C to obtain 16.3 L of sorbitol solution with a refractive index of 8.6% and 8.4 L of maltitol solution with a refractive index of 32.0% as required. In the sorbitol solution, the mass content of sorbitol is 76.85% and the mass content of maltitol is 5.68%. In the maltitol solution, the mass content of maltitol is 59.85% and the mass content of sorbitol is 22.96%.
[0032] Example 3
[0033] The third example of the method for separating sorbitol solution and maltitol solution from polyol solution in the present invention includes the following steps: Step 31: Take 15 L of polyol solution with a refractive index of 42%, add 12.3 L of high-purity water, and dilute it to raw materials with a refractive index of 25.2%. In the polyol solution, the mass content of maltitol is 31.53% and the mass content of sorbitol is 32.46%.
[0034] Step 32: Add 117 g of activated carbon to the raw materials, perform decolorization treatment at an operating temperature of 70 °C for 1 h, and then carry out vacuum filtration to obtain raw materials with a light transmittance of 90%.
[0035] Step 33: Ultrafilter the raw materials after filtration treatment using an ultrafiltration membrane with a molecular weight cut-off of 3.5×10^3 at an operating pressure of 10 bar to obtain 22.4 L of dilute solution with a refractive index of 21.5% and 4.9 L of concentrated solution with a refractive index of 38.3%. In the dilute solution, the mass content of sorbitol is 42.83% and the mass content of maltitol is 40.53%.
[0036] Step 34: Use a nanofiltration membrane with a molecular weight cut-off of 500 to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane. The operating pressure is 30 bar and the operating temperature is 45 °C to obtain 14.6 L of 11.0% sorbitol solution and 7.8 L of 39.4% maltitol solution as required. In the sorbitol solution, the mass content of sorbitol is 82.65% and the mass content of maltitol is 7.12%. In the maltitol solution, the mass content of maltitol is 55.95% and the mass content of sorbitol is 24.48%.
[0037] Example 4
[0038] The fourth example of the method for separating sorbitol solution and maltitol solution from polyol solution in the present invention includes the following steps: Step 41: Take 15 L of polyol solution with a refractive index of 40%, add 27.7 L of high-purity water to dilute it into a raw material with a refractive index of 21.0%. In the polyol solution, the mass content of maltitol is 40.00% and the mass content of sorbitol is 30.00%.
[0039] Step 42: Add 45 g of activated carbon to the raw material, perform decolorization treatment at an operating temperature of 70 °C for 1 h, and then perform vacuum filtration to obtain a raw material with a light transmittance (420 nm, 10 cm cuvette) of 94%.
[0040] Step 43: Ultrafilter the raw material after filtration using an ultrafiltration membrane with a relative molecular mass of 3.5×10^3 at an operating pressure of 10 bar to obtain 35.6 L of dilute solution with a refractive index of 13.9% and 6.9 L of concentrated solution with a refractive index of 24.5%. In the dilute solution, the mass content of sorbitol is 38.83% and the mass content of maltitol is 46.53%.
[0041] Step 44: Use a nanofiltration membrane with a molecular weight cut-off of 1000 to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane. The operating pressure is 30 bar and the operating temperature is 45 °C to obtain 23.3 L of sorbitol solution with a refractive index of 6.4% and 12.2 L of maltitol solution with a refractive index of 27.1% as required. In the sorbitol solution, the mass content of sorbitol is 78.65% and the mass content of maltitol is 7.94%. In the maltitol solution, the mass content of maltitol is 62.57% and the mass content of sorbitol is 22.41%.
[0042] Example 5
[0043] The fifth example of the method for separating sorbitol solution and maltitol solution from polyol solution in the present invention includes the following steps: Step 51: Take 15 L of polyol solution with a refractive index of 40%, add 9.5 L of high-purity water, and dilute it into a raw material with a refractive index of 26.0%. In the polyol solution, the mass content of maltitol is 30.00% and the mass content of sorbitol is 40.00%.
[0044] Step 52: Add 269 g of activated carbon to the raw material, perform decolorization treatment at an operating temperature of 70 °C for 1 h, and then perform vacuum filtration to obtain a raw material with a light transmittance (420 nm, 10 cm colorimetric cell) of 93%.
[0045] Step 53: Ultrafilter the raw material after filtration using an ultrafiltration membrane with a molecular weight cut-off of 3.5×10^3 at an operating pressure of 10 bar to obtain 18.8 L of dilute solution with a refractive index of 22.0% and 5.7 L of concentrated solution with a refractive index of 38.6%. In the dilute solution, the mass content of sorbitol is 51.11% and the mass content of maltitol is 39.53%.
[0046] Step 54: Use a 500 molecular weight nanofiltration membrane to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane at an operating pressure of 30 bar and an operating temperature of 45 °C to obtain 12.3 L of sorbitol solution with a refractive index of 11.4% and 6.5 L of maltitol solution with a refractive index of 39.9% as required. In the sorbitol solution, the mass content of sorbitol is 84.65% and the mass content of maltitol is 7.72%. In the maltitol solution, the mass content of maltitol is 55.07% and the mass content of sorbitol is 35.15%.
[0047] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for separating sorbitol solution and maltitol solution from a polyol solution, characterized in that, It includes the following steps: Step 1: Select a polyol solution with a maltitol mass content of 30.00% - 40.00% and a sorbitol mass content of 30.00% - 40.00%, and dilute and blend the polyol solution into a raw material with a refractive index of 19.7% - 26.0%; Step 2: Add activated carbon with a mass ratio of 0.1% - 1% to the raw material, perform a decolorization treatment at 70 °C for 1 h, and then perform a vacuum filtration treatment; Step 3: Select an ultrafiltration membrane with a relative molecular mass of 3.5×10^3 to perform ultrafiltration treatment on the raw material after filtration, and obtain a dilute solution and a concentrated solution respectively. Sorbitol and maltitol pass through the ultrafiltration membrane and enter the dilute solution, while macromolecular fusel alcohols enter the concentrated solution; Step 4: Use a nanofiltration membrane with a molecular weight of 500 - 1000 to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane. The nanofiltration pressure is 30 bar, and the nanofiltration temperature is 45 °C to obtain the required sorbitol solution and maltitol solution respectively; in the sorbitol solution, the mass content of sorbitol is 76.17%, and in the maltitol solution, the mass content of maltitol is 55.07%.
2. The method for separating sorbitol solution and maltitol solution from a polyol solution according to claim 1, characterized in that, It includes the following steps: Step 11: Take 15 L of a polyol solution with a refractive index of 40%, add 17.3 L of high-purity water, and dilute it into a raw material with a refractive index of 20.1%. In the polyol solution, the mass content of maltitol is 30.14%, and the mass content of sorbitol is 32.01%; Step 12: Add 69 g of activated carbon to the raw material, perform a decolorization treatment at an operating temperature of 70 °C for 1 h, and then perform a vacuum filtration to obtain a raw material with a light transmittance of 87%; Step 13: Perform ultrafiltration treatment on the raw material after filtration using an ultrafiltration membrane with a relative molecular mass of 3.5×10^3. The operating pressure is 10 bar to obtain 27.2 L of a dilute solution with a refractive index of 17.6% and 4.9 L of a concentrated solution with a refractive index of 32.7%. In the dilute solution, the mass content of sorbitol is 42.14%, and the mass content of maltitol is 38.23%; Step 14: Use a nanofiltration membrane with a molecular weight of 1000 to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane. The operating pressure is 30 bar, and the operating temperature is 45 °C to obtain 19.5 L of a sorbitol solution with a refractive index of 9.0% and 7.7 L of a maltitol solution with a refractive index of 37.1% respectively. In the sorbitol solution, the mass content of sorbitol is 76.17%, and the mass content of maltitol is 5.14%; in the maltitol solution, the mass content of maltitol is 56.35%, and the mass content of sorbitol is 23.54%.
3. The method for separating sorbitol solution and maltitol solution from a polyol solution according to claim 1, characterized in that, It includes the following steps: Step 21: Take 15 L of a polyol solution with a refractive index of 35%, add 13.9 L of high-purity water, and dilute it into a raw material with a refractive index of 19.7%. In the polyol solution, the mass content of maltitol is 33.23%, and the mass content of sorbitol is 30.17%; Step 22: Add 186 g of activated carbon to the raw material, perform a decolorization treatment at an operating temperature of 70 °C for 1 h, and then perform a vacuum filtration to obtain a raw material with a light transmittance of 90%; Step 23: Ultrafilter the raw materials after suction filtration using an ultrafiltration membrane with a molecular weight cut-off of 3.5×10^3 at an operating pressure of 10 bar to obtain 24.7 L of a dilute solution with a refractive index of 17.0% and 4.2 L of a concentrated solution with a refractive index of 34.4%. In the dilute solution, the mass content of sorbitol is 40.65% and the mass content of maltitol is 43.32%. Step 24: Use an 800 molecular weight nanofiltration membrane to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane at an operating pressure of 30 bar and an operating temperature of 45°C to obtain 16.3 L of a sorbitol solution with a refractive index of 8.6% and 8.4 L of a maltitol solution with a refractive index of 32.0% as required. In the sorbitol solution, the mass content of sorbitol is 76.85% and the mass content of maltitol is 5.68%. In the maltitol solution, the mass content of maltitol is 59.85% and the mass content of sorbitol is 22.96%.
4. The method for separating sorbitol solution and maltitol solution from a polyol solution according to claim 1, characterized in that, It includes the following steps: Step 31: Take 15 L of a polyol solution with a refractive index of 42% and add 12.3 L of high-purity water to dilute it into a raw material with a refractive index of 25.2%. In the polyol solution, the mass content of maltitol is 31.53% and the mass content of sorbitol is 32.46%. Step 32: Add 117 g of activated carbon to the raw material and perform decolorization treatment at an operating temperature of 70°C for 1 h, and then perform vacuum suction filtration to obtain a raw material with a light transmittance of 90%. Step 33: Ultrafilter the raw materials after suction filtration using an ultrafiltration membrane with a molecular weight cut-off of 3.5×10^3 at an operating pressure of 10 bar to obtain 22.4 L of a dilute solution with a refractive index of 21.5% and 4.9 L of a concentrated solution with a refractive index of 38.3%. In the dilute solution, the mass content of sorbitol is 42.83% and the mass content of maltitol is 40.53%. Step 34: Use a 500 molecular weight nanofiltration membrane to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane at an operating pressure of 30 bar and an operating temperature of 45°C to obtain 14.6 L of a sorbitol solution with a refractive index of 11.0% and 7.8 L of a maltitol solution with a refractive index of 39.4% as required. In the sorbitol solution, the mass content of sorbitol is 82.65% and the mass content of maltitol is 7.12%. In the maltitol solution, the mass content of maltitol is 55.95% and the mass content of sorbitol is 24.48%.
5. The method for separating sorbitol solution and maltitol solution from a polyol solution as claimed in claim 1, characterized in that, It includes the following steps: Step 41: Take 15 L of a polyol solution with a refractive index of 40% and add 27.7 L of high-purity water to dilute it into a raw material with a refractive index of 21.0%. In the polyol solution, the mass content of maltitol is 40.00% and the mass content of sorbitol is 30.00%. Step 42: Add 45 g of activated carbon to the raw material and perform decolorization treatment at an operating temperature of 70°C for 1 h, and then perform vacuum suction filtration to obtain a raw material with a light transmittance of 94%. Step 43: Ultrafilter the raw materials after suction filtration using an ultrafiltration membrane with a molecular weight cut-off of 3.5×10^3 at an operating pressure of 10 bar to obtain 35.6 L of dilute solution with a refractive index of 13.9% and 6.9 L of concentrated solution with a refractive index of 24.5%. In the dilute solution, the mass content of sorbitol is 38.83% and the mass content of maltitol is 46.53%. Step 44: Use a nanofiltration membrane with a molecular weight cut-off of 1000 to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane at an operating pressure of 30 bar and an operating temperature of 45°C to obtain 23.3 L of sorbitol solution with a refractive index of 6.4% and 12.2 L of maltitol solution with a refractive index of 27.1% as required. In the sorbitol solution, the mass content of sorbitol is 78.65% and the mass content of maltitol is 7.94%. In the maltitol solution, the mass content of maltitol is 62.57% and the mass content of sorbitol is 22.41%.
6. The method for separating sorbitol solution and maltitol solution from a polyol solution according to claim 1, characterized in that, It includes the following steps: Step 51: Take 15 L of polyol solution with a refractive index of 40%, add 9.5 L of high-purity water, and dilute it to a raw material with a refractive index of 26.0%. In the polyol solution, the mass content of maltitol is 30.00% and the mass content of sorbitol is 40.00%. Step 52: Add 269 g of activated carbon to the raw materials, perform decolorization treatment at an operating temperature of 70°C for 1 h, and then perform vacuum suction filtration to obtain raw materials with a light transmittance of 93%. Step 53: Ultrafilter the raw materials after suction filtration using an ultrafiltration membrane with a molecular weight cut-off of 3.5×10^3 at an operating pressure of 10 bar to obtain 18.8 L of dilute solution with a refractive index of 22.0% and 5.7 L of concentrated solution with a refractive index of 38.6%. In the dilute solution, the mass content of sorbitol is 51.11% and the mass content of maltitol is 39.53%. Step 54: Use a nanofiltration membrane with a molecular weight cut-off of 500 to perform nanofiltration separation on the dilute solution treated by the ultrafiltration membrane at an operating pressure of 30 bar and an operating temperature of 45°C to obtain 12.3 L of sorbitol solution with a refractive index of 11.4% and 6.5 L of maltitol solution with a refractive index of 39.9% as required. In the sorbitol solution, the mass content of sorbitol is 84.65% and the mass content of maltitol is 7.72%. In the maltitol solution, the mass content of maltitol is 55.07% and the mass content of sorbitol is 35.15%.