A process for recovering inositol from potassium dihydrogen phosphate mother liquor

Abstract

This invention relates to the field of inositol production technology, and particularly to a process for recovering inositol from potassium dihydrogen phosphate mother liquor, comprising the following steps: (1) taking potassium dihydrogen phosphate mother liquor, adding calcium hydroxide and stirring to mix, controlling the pH of the reaction solution to be not less than 10, filtering after the reaction is completed, and collecting the filtrate and solid phase separately; (2) taking the filtrate from step (1), concentrating the concentrated solution and then cooling and crystallizing, and collecting the crude inositol and crystallization mother liquor separately; (3) taking the crude inositol from step (2), adding purified water, heating and stirring to dissolve, filtering the filtrate and decolorizing it, and collecting the decolorized solution for later use; (4) taking the decolorized solution from step (3), and after precision filtration, cooling and crystallizing, centrifuging and drying, obtaining the inositol product. This process can obtain a high-yield, high-purity inositol product, avoiding resource waste and increasing economic benefits for enterprises.

Description

Technical Field

[0001] This invention relates to the field of inositol production technology, and in particular to a process for recovering inositol from potassium dihydrogen phosphate mother liquor. Background Technology

[0002] Corn soaking water is a byproduct of wet corn starch production, containing 1-2% phytic acid. Currently, there are reported methods for recovering phytic acid from corn soaking water to prepare potassium phytate, followed by hydrolysis, separation, concentration, and crystallization to produce inositol and potassium dihydrogen phosphate. Compared to traditional potassium dihydrogen phosphate production processes such as neutralization and metathesis, using corn soaking water as a raw material not only avoids the environmental damage caused by phosphate rock mining but also achieves the recycling of phosphorus resources from plants, resulting in significant economic and social benefits.

[0003] Current processes typically separate potassium dihydrogen phosphate (KH2PO4) and inositol obtained from corn soaking water using simulated moving bed chromatography, yielding KH2PO4 and inositol solutions. However, both inositol and KH2PO4 are readily soluble in water. In actual production, limitations imposed by chromatographic resin separation and process parameters mean that the resulting KH2PO4 solution usually contains a certain concentration of inositol. During KH2PO4 crystallization, inositol, pigments, proteins, calcium, magnesium, and other substances gradually accumulate in the mother liquor, eventually reaching a KH2PO4 concentration of 20-40 kg / L. Currently, KH2PO4 crystallization mother liquor is mostly sold directly as liquid fertilizer, resulting in significant underutilization of its inositol value. Therefore, it is necessary to establish a process for recovering inositol from KH2PO4 mother liquor to address these issues. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a process for recovering inositol from potassium dihydrogen phosphate mother liquor, which can obtain high-yield and high-purity inositol products, avoid resource waste, and increase economic benefits for enterprises.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A process for recovering inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0007] (1) Take the potassium dihydrogen phosphate mother liquor, add calcium hydroxide and stir to mix, control the pH of the reaction solution to be not less than 10, filter after the reaction is completed, and collect the filtrate and solid phase respectively;

[0008] (2) Take the filtrate from step (1), concentrate it, then cool it down to crystallize and centrifuge it to collect crude inositol and crystallization mother liquor respectively.

[0009] (3) Take the crude inositol product described in step (2), add purified water, heat and stir to dissolve, filter the filtrate and decolorize it, and collect the decolorized liquid for later use;

[0010] (4) Take the decolorizing solution described in step (3), and after precision filtration, cooling crystallization, centrifugation and drying, obtain the inositol product.

[0011] As an improved technical solution, in step (1), the calcium hydroxide and the phosphate ions in the potassium dihydrogen phosphate mother liquor are added in a molar ratio of 1:1, and the pH of the reaction solution is controlled to be 10-11.

[0012] As an improved technical solution, the solid content of the concentrate in step (2) is 55-65 wt%.

[0013] As an improved technical solution, the temperature for cooling and crystallizing the concentrate in step (2) is 25-35℃, and the crystallization time is 8-12h.

[0014] As an improved technical solution, in step (3), the crude inositol and the purified water are added at a ratio of 1:1.5-2 and heated to 85-95°C.

[0015] As an improved technical solution, the filtrate after filtration in step (3) enters the decolorization column at a flow rate of 1-2 BV / h for decolorization treatment. The packing material in the decolorization column is ultra-low ash activated carbon particles with an ash content ≤0.1%, a particle size of 0.5-2 mm, a specific surface area of ​​1200-1500 m² / g, and an iodine value of 800-1200 mg / g.

[0016] As an improved technical solution, the decolorizing solution in step (4) is cooled to 25-35℃ for crystallization, and the crystallization time is 8-10h.

[0017] As an improved technical solution, the drying temperature in step (4) is 105-115℃ and the drying time is 6-8h.

[0018] After adopting the above technical solution, the beneficial effects of the present invention are:

[0019] This invention involves first adding calcium hydroxide to the collected potassium dihydrogen phosphate mother liquor. Some organic impurities in the mother liquor, such as proteins and pigments, can also undergo a flocculation reaction with the calcium hydroxide and be removed by filtration. The collected filtrate is then concentrated, cooled for crystallization, and centrifuged. The resulting crude inositol product is then dissolved in purified water and fed into a decolorization column for decolorization. The collected decolorized solution is then cooled for crystallization, centrifuged, and dried to obtain the inositol product. This process effectively recovers inositol from the potassium dihydrogen phosphate mother liquor, avoiding resource waste and increasing economic benefits for enterprises. Attached Figure Description

[0020] Figure 1 This is a picture of the inositol product prepared in Example 3. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Example 1

[0023] A process for recovering inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0024] (1) Take 1000L of potassium dihydrogen phosphate mother liquor (inositol concentration is 0.02kg / L, potassium dihydrogen phosphate concentration is 0.156kg / L), add 85kg of calcium hydroxide and stir to mix. Control the pH of the reaction solution to 10. After the reaction is completed, filter and collect 900L of filtrate and 270kg of solid phase (after drying, sell as feed additive tricalcium phosphate).

[0025] (2) Take 900L of the filtrate from step (1), concentrate it to 130L of the concentrated liquid with a solid content of 55wt%, then cool it to 25℃, crystallize for 8 hours, centrifuge, and collect 17kg of crude inositol and 125L of crystallization mother liquor (to be sold as phosphorus and potassium liquid fertilizer).

[0026] (3) Take 17 kg of crude inositol from step (2), add 25.5 L of purified water at a ratio of 1:1.5, heat to 85℃, stir to dissolve, filter and then put 32.5 L of the filtrate into a 20 L decolorizing column (the packing material is ultra-low ash activated carbon particles, the ash content of the activated carbon particles is ≤0.1%, the particle size is 0.5-2 mm, the specific surface area is 1200-1500 m² / g, and the iodine value is 800-1200 mg / g) at a flow rate of 1 BV / h for decolorization treatment, and collect 32.5 L of decolorized liquid for later use;

[0027] (4) Take 32.5L of the decolorizing solution from step (3), filter it precisely, then cool it to 25℃, crystallize for 8 hours, centrifuge, and dry (drying temperature is 105℃, drying time is 6 hours) to obtain the inositol product.

[0028] Example 2

[0029] A process for recovering inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0030] (1) Take 1000L of potassium dihydrogen phosphate mother liquor (inositol concentration is 0.025kg / L, potassium dihydrogen phosphate concentration is 0.134kg / L), add 73kg of calcium hydroxide and stir to mix. Control the pH of the reaction solution to 10.2. After the reaction is completed, filter and collect 900L of filtrate and 230kg of solid phase (after drying, sell as feed additive tricalcium phosphate).

[0031] (2) Take 900L of the filtrate from step (1), concentrate it to obtain 110L of concentrated solution with a solid content of 58wt%, then cool it to 28℃, crystallize for 9h, centrifuge, and collect 21.5kg of crude inositol and 100L of crystallization mother liquor (to be sold as phosphorus and potassium liquid fertilizer).

[0032] (3) Take 21.5 kg of crude inositol from step (2), add 34.5 L of purified water at a ratio of 1:1.6, heat to 88℃, stir to dissolve, and filter. Then, put 45.5 L of the filtrate into a 25 L decolorizing column (the packing material is ultra-low ash activated carbon particles, the ash content of the activated carbon particles is ≤0.1%, the particle size is 0.5-2 mm, the specific surface area is 1200-1500 m² / g, and the iodine value is 800-1200 mg / g) at a flow rate of 1.2 BV / h for decolorization treatment. Collect 45.5 L of the decolorized liquid for later use.

[0033] (4) Take 45.5L of the decolorizing solution from step (3), filter it precisely, then cool it to 28℃, crystallize it for 8.5h, centrifuge it, and dry it (drying temperature is 109℃, drying time is 6.5h) to obtain the inositol product.

[0034] Example 3

[0035] A process for recovering inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0036] (1) Take 1000L of potassium dihydrogen phosphate mother liquor (inositol concentration is 0.03kg / L, potassium dihydrogen phosphate concentration is 0.123kg / L), add 67kg of calcium hydroxide and stir to mix. Control the pH of the reaction solution to 10.5. After the reaction is completed, filter and collect 950L of filtrate and 212kg of solid phase (after drying, sell as feed additive tricalcium phosphate).

[0037] (2) Take 950L of the filtrate from step (1), concentrate it to obtain 105L of concentrated solution with a solid content of 60wt%, then cool it to 30℃, crystallize for 10h, centrifuge, and collect 26.5kg of crude inositol and 95L of crystallization mother liquor (to be sold as phosphorus and potassium liquid fertilizer).

[0038] (3) Take 26.5 kg of crude inositol from step (2), add 45 L of purified water at a ratio of 1:1.7, heat to 90 °C, stir to dissolve, filter and then 60 L of the filtrate is fed into a 30 L decolorizing column (the packing material is ultra-low ash activated carbon particles, the ash content of the activated carbon particles is ≤0.1%, the particle size is 0.5-2 mm, the specific surface area is 1200-1500 m² / g, and the iodine value is 800-1200 mg / g) at a flow rate of 1.5 BV / h for decolorization treatment, and collect 60 L of decolorized liquid for later use;

[0039] (4) Take 60L of the decolorizing solution from step (3), filter it precisely, then cool it to 30℃, crystallize for 9h, centrifuge, and dry (drying temperature is 110℃, drying time is 7h) to obtain the inositol product.

[0040] Example 4

[0041] A process for recovering inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0042] (1) Take 1000L of potassium dihydrogen phosphate mother liquor (inositol concentration is 0.035kg / L, potassium dihydrogen phosphate concentration is 0.11kg / L), add 60kg of calcium hydroxide and stir to mix. Control the pH of the reaction solution to 10.8. After the reaction is completed, filter and collect 950L of filtrate and 190kg of solid phase (after drying, sell as feed additive tricalcium phosphate).

[0043] (2) Take 950L of the filtrate from step (1), concentrate it to obtain 100L of concentrated liquid with a solid content of 62wt%, then cool it to 32℃, crystallize for 11h, centrifuge, and collect 30kg of crude inositol and 85L of crystallization mother liquor (to be sold as phosphorus and potassium liquid fertilizer).

[0044] (3) Take 30 kg of crude inositol from step (2), add 56.5 L of purified water at a ratio of 1:1.8, heat to 92℃, stir to dissolve, filter and then enter 75 L of the filtrate into a 35 L decolorizing column (the packing material is ultra-low ash activated carbon particles, the ash content of the activated carbon particles is ≤0.1%, the particle size is 0.5-2 mm, the specific surface area is 1200-1500 m² / g, and the iodine value is 800-1200 mg / g) for decolorization treatment, and collect 75 L of the decolorized liquid for later use;

[0045] (4) Take 75L of the decolorizing solution from step (3), filter it precisely, then cool it to 32℃, crystallize for 9.5h, centrifuge, and dry (drying temperature is 112℃, drying time is 7.5h) to obtain the inositol product.

[0046] Example 5

[0047] A process for recovering inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0048] (1) Take 1000L of potassium dihydrogen phosphate mother liquor (inositol concentration is 0.04kg / L, potassium dihydrogen phosphate concentration is 0.101kg / L), add 55kg of calcium hydroxide and stir to mix. Control the pH of the reaction solution to 11. After the reaction is completed, filter and collect 950L of filtrate and 170kg of solid phase (after drying, sell as feed additive tricalcium phosphate).

[0049] (2) Take 950L of the filtrate from step (1), concentrate it to obtain 90L of concentrated solution with a solid content of 65wt%, then cool it to 35℃, crystallize for 12h, centrifuge, and collect 33.5g of crude inositol and 80L of crystallization mother liquor (to be sold as phosphorus and potassium liquid fertilizer).

[0050] (3) Take 33.5 kg of crude inositol from step (2), add 67 L of purified water at a ratio of 1:2, heat to 95 °C, stir to dissolve, filter and then enter 86 L of the filtrate into a 40 L decolorizing column (the packing material is ultra-low ash activated carbon particles, the ash content of the activated carbon particles is ≤0.1%, the particle size is 0.5-2 mm, the specific surface area is 1200-1500 m² / g, and the iodine value is 800-1200 mg / g) at a flow rate of 2 BV / h for decolorization treatment, and collect 86 L of the decolorized liquid for later use;

[0051] (4) Take 86L of the decolorizing solution from step (3), filter it precisely, then cool it to 35℃, crystallize for 10h, centrifuge, and dry (drying temperature is 115℃, drying time is 8h) to obtain the inositol product.

[0052] To better demonstrate the superior technical effects of the process method of the present invention, 15 comparative examples are provided with reference to Example 3. The inositol products obtained from Examples 1-5 and Comparative Examples 1-10 are shown in Table 1.

[0053] Comparative Example 1

[0054] Unlike Example 3, in step (1), the pH of the reaction solution is controlled to be 9, while the rest of the operation is the same.

[0055] Comparative Example 2

[0056] Unlike Example 3, the pH of the reaction solution was controlled at 12 in step (1), while the rest of the operation was the same.

[0057] Comparative Example 3

[0058] Unlike Example 3, the solid content of the concentrate in step (2) is 50 wt%, while the rest of the operation is the same.

[0059] Comparative Example 4

[0060] Unlike Example 3, the solid content of the concentrate in step (2) is 70 wt%, while the rest of the operation is the same.

[0061] Comparative Example 5

[0062] Unlike Example 3, in step (2), the temperature was lowered to 20°C for crystallization, while the rest of the operation was the same.

[0063] Comparative Example 6

[0064] Unlike Example 3, in step (2), the temperature was lowered to 40°C for crystallization, while the rest of the operation was the same.

[0065] Comparative Example 7

[0066] Unlike Example 3, the crystallization time in step (2) is 7 hours, while the rest of the operation is the same.

[0067] Comparative Example 8

[0068] Unlike Example 3, the crystallization time in step (2) is 13 hours, while the rest of the operation is the same.

[0069] Comparative Example 9

[0070] Unlike Example 3, in step (3), crude inositol and purified water were added in a ratio of 1:3 with 79.5L of purified water, and the rest of the operation was the same.

[0071] Comparative Example 10

[0072] Unlike Example 3, the filler in the decolorization column in step (3) is ordinary activated carbon particles (the activated carbon particles have an ash content of 3%, a particle size of 0.5-2 mm, a specific surface area of ​​800-1000 m² / g, and an iodine value of 600-800 mg / g; the rest of the operation is the same).

[0073] Comparative Example 11

[0074] Unlike Example 3, in step (3), the crude inositol was heated to 80°C after being added to purified water, and the rest of the operation was the same.

[0075] Comparative Example 12

[0076] Unlike Example 3, in step (3), crude inositol was heated to 100°C after being added to purified water, while the rest of the operation was the same.

[0077] Comparative Example 13

[0078] Unlike Example 3, the drying temperature in step (4) is 120°C, while the rest of the operation is the same.

[0079] Comparative Example 14

[0080] Unlike Example 3, the crystallization time in step (4) is 12 hours, while the rest of the operation is the same.

[0081] Comparative Example 15

[0082] Unlike Example 3, the crystallization time in step (4) is 6 hours, while the rest of the operation is the same.

[0083] Table 1

[0084]

[0085]

[0086] The data in Table 1 shows that the inositol products obtained using the process method of the present invention in Examples 1-5 have significantly better overall performance than those in Comparative Examples 1-15 in terms of yield, output, content, color, and heavy metal content.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for recovering inositol from potassium dihydrogen phosphate mother liquor, characterized in that, Includes the following steps: (1) Take the potassium dihydrogen phosphate mother liquor, add calcium hydroxide and stir to mix, control the pH of the reaction solution to 10-11, filter after the reaction is completed, and collect the filtrate and solid phase respectively; the calcium hydroxide and the phosphate in the potassium dihydrogen phosphate mother liquor are added in a molar ratio of 1:

1. (2) Take the filtrate from step (1), concentrate it, and then cool and crystallize it, and centrifuge it to collect crude inositol and mother liquor respectively; the solid content of the concentrate is 55-65 wt%; (3) Take the crude inositol product mentioned in step (2), add purified water, heat and stir to dissolve, filter and decolorize the filtrate, and collect the decolorized liquid for later use; add the crude inositol product and the purified water at a ratio of 1:1.5-2, and heat to 85-95℃; the filtered filtrate enters the decolorization column at a flow rate of 1-2 BV / h for decolorization, the packing material in the decolorization column is ultra-low ash activated carbon particles, the ash content of the activated carbon particles is ≤0.1%, the particle size is 0.5-2mm, the specific surface area is 1200-1500㎡ / g, and the iodine value is 800-1200mg / g; (4) Take the decolorizing solution described in step (3), and after precision filtration, cooling crystallization, centrifugation and drying, obtain the inositol product.

2. The process for recovering inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, The temperature for cooling and crystallizing the concentrate in step (2) is 25-35℃, and the crystallization time is 8-12h.

3. The process for recovering inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, The decolorizing solution described in step (4) is cooled to 25-35℃ for crystallization, and the crystallization time is 8-10h.

4. The process for recovering inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (4), the drying temperature is 105-115℃ and the drying time is 6-8h.

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