Potassium-rich liquid decalcification method based on titanate ion sieve

Abstract

The invention discloses a potassium-rich liquid decalcification method based on a titanate ion sieve, and relates to the technical field of high-salinity water body ion removal, and the removal method comprises the following steps: adding the titanate ion sieve into a potassium-rich liquid water body as an adsorbent under a constant temperature condition, oscillating the potassium-rich liquid added with the adsorbent for a certain period of time, and removing calcium ions in the potassium-rich liquid; calcium ions in a potassium-rich liquid system can be remarkably removed, and then the titanate ion sieve is put into a NaCl solution for elution, so that elution of the calcium ions in the titanate ion sieve is realized. By constructing an efficient decalcification system, efficient removal of calcium ions in the potassium-rich liquid is achieved, meanwhile, cyclic utilization of ionic titanate is achieved, high adsorption capacity can still be kept in multiple cyclic adsorption-desorption cycles, the economic benefits of potassium salt extraction are improved, and the method can meet the actual requirements of industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of calcium ion removal, and specifically to a method for removing calcium from potassium-rich solution based on titanate ion sieve. Background Art

[0002] Potassium-rich solution is an intermediate product in the process of extracting potassium from seawater, mainly used for extracting potassium salts or potassium fertilizers. However, potassium-rich solution often contains high concentrations of Ca 2+ ions, which are likely to cause equipment scaling under high temperature or high concentration conditions, seriously affecting the normal operation of the potassium extraction process. Therefore, it is particularly important to develop effective calcium removal technologies.

[0003] Currently, methods such as chemical precipitation, reverse osmosis, electrodialysis, and ion exchange adsorption are often used in industry to remove Ca 2+ ions from water. Among them, the chemical precipitation method reacts by adding specific chemical reagents with Ca 2+ in water to form insoluble or poorly soluble precipitates, and then separates them from water through solid-liquid separation technologies (such as precipitation, filtration, etc.). For example, by adding NaOH to adjust the pH value to produce precipitation, some Ca 2+ in the water body can be removed. However, the chemical precipitation method will introduce new ions into the water body, and the added materials are difficult to recover. The reverse osmosis technology uses the selective permeability of the semi-permeable membrane for water purification, with advantages such as high ion rejection rate. However, the reverse osmosis technology is not selective, so it is not suitable for extracting Ca 2+ from complex systems. The electrodialysis method uses an externally applied direct current electric field to make anions and cations in the aqueous solution move towards the anode and cathode respectively, and then separates the ions into different chambers through the cation exchange membrane and anion exchange membrane in the device. The electrodialysis technology can intercept Ca 2+ into the raw material chamber by using a selective cation exchange membrane to achieve the purpose of removing Ca 2+ , but this method will cause the enrichment of Ca 2+ in the raw material chamber, resulting in the precipitation and scaling of Ca 2+ in the device. The ion exchange adsorption method uses materials with cation exchange ability, and the cations on the materials can undergo ion exchange with Ca 2+ in the solution. The ion exchange adsorption method is widely used in water treatment, and its high selectivity for cations makes ion exchange adsorption materials widely used in the specific cation removal process under complex systems.

[0004] Titanate ion sieve is a type of A x H 2ae-ax Ti f O 2f+aeThe general term for ·gH2O-type materials, where A is a metal element in the a valence state or an ammonium ion, and e, x, f, and g are all relevant parameters. Except for some titanate ion sieves, titanate ion sieves all exhibit a spatial layered structure. The layer structure is composed of [TiO6] octahedrons, and there are metal cations, hydrogen ions, ammonium ions, etc. between the layers. Due to the extremely large theoretical cation exchange capacity, large specific surface area, fast cation embedding ability, and surface electronegativity in a wide pH range of the titanate ion sieve itself, the titanate ion sieve material has excellent adsorption performance for cations.

[0005] In summary, it is necessary to develop a method for removing calcium from potassium-rich liquid based on titanate ion sieves to achieve the selective removal of Ca 2+ in the potassium-rich liquid. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for removing calcium from potassium-rich liquid based on titanate ion sieves to solve the problems proposed in the above background technology.

[0007] To achieve the above purpose, the present invention provides the following technical solution: A method for removing calcium from potassium-rich liquid based on titanate ion sieves, the method for treating calcium removal from potassium-rich liquid includes the following steps:

[0008] Prepare potassium-rich liquid, adjust the pH, first add titanate for adsorption and calcium removal treatment, and then perform solid-liquid separation to obtain the adsorbed titanate and filtrate. Place the adsorbed titanate in an NaCl solution for elution and a NaOH solution for regeneration.

[0009] Preferably, the eluting NaCl solution uses an NaCl solution with a concentration of 0.1 - 3.0 mol / L, and the concentration is, for example, 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 1.5 mol / L, or 3.0 mol / L, etc.

[0010] Preferably, the regenerating NaOH solution uses a NaOH solution with a concentration of 0.1 - 3.0 mol / L, and the concentration is, for example, 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 1.5 mol / L, or 3.0 mol / L, etc.

[0011] As a preferred technical solution of the present invention, in the calcium-containing potassium-rich liquid, the concentration of Ca 2+ is 0.1 - 5.0 mmol / L, for example, 0.1 mmol / L, 0.2 mmol / L, 1.0 mmol / L, 2.0 mmol / L, 3.5 mmol / L, 5.0 mmol / L, etc.; the concentration of K + is 1 - 10 g / L, for example, 1 g / L, 3 g / L, 7 g / L, 10 g / L.

[0012] As a preferred technical solution of the present invention, the pH of the cobalt-containing organic wastewater is adjusted to 3-8, such as 3, 4, 5 or 6, etc.

[0013] It should be noted that through the research of the inventors, it is found that under the condition of slightly neutral pH value, it is more beneficial for the titanate ion sieve to adsorb calcium ions in the potassium-rich solution.

[0014] As a preferred technical solution of the present invention, the titanate is prepared by a liquid-phase method, and the preparation method includes the following steps: adding nanoscale TiO2 into a NaOH solution, ultrasonically dispersing and then stirring at room temperature; transferring the mixed solution into a reaction kettle for reaction, centrifuging after cooling, washing with deionized water and hydrochloric acid, and drying and grinding.

[0015] Preferably, in the liquid-phase preparation method, the concentration of the NaOH solution is 9-11 mol / L, such as 9 mol / L, 9.5 mol / L, 10 mol / L, 10.5 mol / L or 11 mol / L, etc., and the mass-volume ratio of TiO2 to the NaOH solution is 1 g:(50-70) mL, such as 1 g:50 mL, 1 g:55 mL, 1 g:60 mL, 1 g:65 mL or 1 g:70 mL, etc.

[0016] Preferably, in the liquid-phase preparation method, the temperature of the reaction is 125-180 °C, such as 125 °C, 135 °C, 145 °C, 155 °C, 165 °C, 175 °C or 180 °C, etc., and the reaction time is 1-5 days, such as 1 day, 2 days, 3 days, 3.5 days, 4 days, 4.5 days or 5 days, etc.

[0017] Preferably, in the liquid-phase preparation method, the drying includes drying at 50-70 °C for 10-15 h, the drying temperature is 50-70 °C, such as 50 °C, 52 °C, 55 °C, 57 °C, 60 °C, 62 °C, 65 °C, 67 °C or 70 °C, etc., and the drying time is 10-15 h, such as 10 h, 11 h, 12 h, 13 h, 14 h or 15 h, etc.

[0018] As a preferred technical solution of the present invention, in the adsorption treatment, the dosage of the titanate is 0.1-3.0 g / L, such as 0.1 g / L, 0.5 g / L, 0.7 g / L or 3.0 g / L, etc.

[0019] Preferably, in the adsorption treatment, the adsorption time is 12-72 h, such as 12 h, 24 h, 48 h or 72 h, etc.

[0020] Preferably, in the adsorption treatment, the temperature of the adsorption treatment is 15-90 °C, such as 15 °C, 25 °C, 45 °C, 65 °C, 85 °C, 90 °C.

[0021] Preferably, the calcium-rich potassium solution is the potassium-rich liquid obtained in the potassium extraction process from seawater.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] By precisely regulating the temperature, pH value of the potassium-rich liquid and the dosage of the titanate ion sieve, the present invention constructs an efficient decalcification system, significantly improving the decalcification efficiency. At the same time, through the cyclic elution technology, the adsorbent is effectively regenerated, its service life is extended, resource waste is reduced, and through the exploration of the decalcification conditions of the titanate ion sieve in the potassium-rich liquid, it can be applied to the actual needs of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the structural diagram of the synthesis steps of the titanate ion sieve of the present invention;

[0025] Figure 2 It is the adsorption amount data graph of the titanate ion sieve for Ca 2+ at different temperatures of the present invention;

[0026] Figure 3 It is the adsorption capacity data graph of the titanate ion sieve for Ca 2+ at different pH values of the present invention;

[0027] Figure 4 It is the adsorption capacity data graph of the titanate ion sieve for Ca 2+ at different dosages of the present invention;

[0028] Figure 5 It is the adsorption capacity data graph of the titanate ion sieve for Ca 2+ in the adsorption-elution regeneration cycle of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] To better illustrate the present invention and facilitate understanding of its technical solutions, the typical but non-limiting embodiments of the present invention are as follows:

[0031] Preparation of titanate ion sieve: Disperse 1 g of nano-titanium dioxide into 60 mL of NaOH solution with a concentration of 10 mol / L, stir ultrasonically and then stir at room temperature for 1 h; transfer the mixed solution into a reaction kettle and react at 125 °C for 2 days; after cooling, centrifuge, wash with deionized water and 0.1 mol / L hydrochloric acid until neutral, and then dry in a vacuum drying oven at 60 °C for 12 h, and grind with a mortar to a loose powder state for storage and standby.

[0032] Example 1

[0033] This example provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. The calcium removal method includes the following steps:

[0034] (1) Prepare 1 L of calcium-containing potassium-rich solution. The potassium-rich solution is obtained from a certain potassium extraction section of seawater. After detection: Ca 2+ The concentration is 0.8 mmol / L, the pH is 4.6, and the pH is adjusted to 8 with NaOH.

[0035] (2) Add titanate ion sieve to the potassium-rich solution at a dosage of 3.0 g / L and adsorb at 60 °C. Strengthen the mass transfer process by shaking, and control the adsorption time to be 10 min.

[0036] (3) After solid-liquid separation, obtain the adsorbed titanate ion sieve and filtrate. Perform elution and regeneration treatment on the adsorbed titanate ion sieve. First, elute with 0.1 mol / L NaCl solution, and then regenerate with 0.1 mol / L NaOH. Dry at 60 °C for 12 h to obtain regenerated titanate.

[0037] Example 2

[0038] This example provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Example 1, the difference is only that: the adsorption time is 20 min.

[0039] Example 3

[0040] This example provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Example 1, the difference is only that: the adsorption time is 40 min.

[0041] Example 4

[0042] This example provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Example 1, the difference is only that: the adsorption time is 80 min.

[0043] Example 5

[0044] This embodiment provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Embodiment 1, the only difference is that the adsorption treatment time is 120 min.

[0045] Embodiment 6

[0046] This embodiment provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Embodiment 1, the only difference is that the adsorption treatment time is 240 min.

[0047] Embodiment 7

[0048] This embodiment provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Embodiment 1, the only difference is that the adsorption treatment time is 480 min.

[0049] Embodiment 8

[0050] This embodiment provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Embodiment 1, the only difference is that the adsorption treatment time is 720 min.

[0051] Comparative Example 1

[0052] This comparative example provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Embodiment 8, the only difference is that the adsorption treatment temperature is 25 °C.

[0053] Comparative Example 2

[0054] This comparative example provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Embodiment 8, the only difference is that the dosage of titanate ion sieve is 1 g / L.

[0055] Comparative Example 3

[0056] This comparative example provides a method for removing calcium from potassium-rich solution based on titanate ion sieve. Compared with Embodiment 8, the only difference is that the pH of adsorption treatment is 3.

[0057] Table 1

[0058]

[0059] (1) Comparing Embodiments 1-8 of the present invention, during the process of removing calcium from the potassium-rich solution, the adsorption of the titanate ion sieve is basically saturated at 720 min, which can effectively ensure that the removal rate reaches more than 90%.

[0060] (2) Comparing Embodiment 8 with Comparative Example 1, since the adsorption temperature in Comparative Example 1 is reduced to 25 °C, compared with 60 °C, the adsorption equilibrium changes in the low-temperature environment, and the adsorption amount of the titanate ion sieve for Ca 2+ is significantly reduced.

[0061] (3) Comparing Example 8 with Comparative Example 2, since the dosage of the titanate ion sieve in Comparative Example 2 was reduced to 1 g / L, compared with 1 g / L, the too low dosage led to a significant shortage of the number of adsorption sites, and the adsorption amount of the titanate ion sieve for Ca 2+ was significantly reduced.

[0062] (4) Comparing Example 8 with Comparative Example 3, since the pH of the potassium-rich liquid system in Comparative Example 3 was adjusted to 3, the surface electronegativity of the titanate ion sieve was weak, and the adsorption amount of the titanate ion sieve for Ca 2+ was significantly reduced.

[0063] All the regenerated titanate ion sieves obtained by drying Example 8 were used for the next cycle experiment, that is, the operation of Example 8 was repeated 5 times in total to evaluate the stability of the titanate. As Figure 5 shown, in each repeated experiment, after adding the titanate for 10 min, the curve of the change of the Ca 2+ adsorption capacity with time in the system was monitored to determine the regeneration effect of the titanate ion sieve and explore the cyclic performance of the regenerated titanate for adsorbing cobalt ions. It can be seen that the material still maintained a high reaction activity after five cycles.

[0064] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0065] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for removing calcium from potassium-rich liquid based on titanium-based ion sieve, characterized in that, The method for decalcifying the potassium-rich liquid comprises the following steps: Prepare the potassium-rich liquid, adjust the pH, add the titanate ion sieve for ion exchange decalcification treatment, and then perform solid-liquid separation to obtain the adsorbed titanate ion sieve and the decalcified potassium-rich liquid.

2. The method for removing calcium from potassium-rich solution according to claim 1, characterized in that, The method for decalcifying the potassium-rich liquid further comprises: Performing a regeneration treatment on the adsorbed titanate ion sieve to obtain a regenerated titanate ion sieve for reuse; wherein, the regeneration treatment comprises: adding the adsorbed titanate ion sieve to an NaCl solution for elution to obtain a regenerated titanate ion sieve.

3. The method for removing calcium from potassium-rich liquid according to claim 2, wherein In the regeneration treatment, the cyclic elution comprises: Adding the titanate ion sieve separated after decalcification to an NaCl solution for shaking for elution; then adding the titanate ion sieve to an NaOH solution for shaking for regeneration; and finally obtaining a regenerated titanate ion sieve through separation. Preferably, the elution is performed using an NaCl solution with a concentration of 0.1 - 3.0 mol / L, and the elution shaking time is 1 - 4 hours. Preferably, the regeneration is performed using an NaOH solution with a concentration of 0.1 - 3.0 mol / L, and the regeneration shaking time is 1 - 4 hours.

4. The method for decalcifying a potassium-rich solution according to any one of claims 1 to 3, characterized in that, In the calcium-rich potassium solution, Ca 2+ has a concentration of 0.1 - 5.0 mmol / L, and K + has a concentration of 1 - 10 g / L.

5. The method for decalcifying potassium-rich solution according to any one of claims 1-3, characterized in that, Adjusting the pH to make the pH value of the calcium-containing potassium-rich liquid be 3 - 8.

6. The method for decalcifying a potassium-rich solution according to any one of claims 1 to 3, characterized in that, The titanate is a titanate ion sieve with a layered structure, such as Na x H 2-x Ti3O7·H2O.

7. The method for decalcifying potassium-rich solution according to claim 6, characterized in that, The titanate ion sieve is prepared by a liquid phase method, and the preparation method comprises the following steps: adding nanoscale TiO₂ to a 9 - 11 mol / L NaOH solution, performing ultrasonic dispersion and stirring at 25°C for 1 - 4 h; transferring the mixed solution to a reaction kettle and reacting at 125 - 180°C for 1 - 5 days; centrifuging after cooling, washing with deionized water and 0.1 mol / L hydrochloric acid until neutral, and drying and grinding.

8. The potassium-rich liquid decalcification treatment method according to any one of claims 1-3, characterized in that, In the adsorption treatment, the dosage of the titanate is 0.1 - 3.0 g / L.

9. The method for decalcifying potassium-rich solution according to any one of claims 1-3, characterized in that, In the adsorption treatment, the temperature of the adsorption treatment is 15 - 90°C.

10. The method for removing calcium from potassium-rich solution according to claim 1, wherein The calcium-containing liquid is a potassium-rich liquid obtained in the potassium extraction process from seawater.

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