Calcium polystyrene sulfonate and preparation method thereof

Abstract

The present application relates to the field of pharmaceutical chemistry technology, and specifically discloses a calcium polystyrene sulfonate and a preparation method thereof. The preparation method of calcium polystyrene sulfonate comprises the following steps: S1: uniformly mixing sodium polystyrene sulfonate microspheres with an aqueous dispersion of zeolite, heating and mixing, solid-liquid separation, and washing to obtain primary sodium polystyrene sulfonate microspheres; S2: preparing the primary sodium polystyrene sulfonate microspheres into suspension one, passing suspension one and calcium chloride solution into a microchannel reactor at the same time, reacting, solid-liquid separation, washing, preparing suspension two, passing suspension two and calcium chloride solution into a microchannel reactor at the same time, reacting, solid-liquid separation, washing, preparing suspension three, passing suspension three and calcium chloride solution into a microchannel reactor at the same time, reacting, solid-liquid separation, washing, and drying to obtain calcium polystyrene sulfonate. The calcium polystyrene sulfonate prepared in the present application has a high calcium loading rate and potassium ion exchange capacity.

Description

Technical Field

[0001] The present application relates to the technical field of pharmaceutical chemistry, and more specifically, to calcium polystyrene sulfonate and a preparation method thereof. Background Art

[0002] Sodium polystyrene sulfonate, commonly known as potassium-lowering resin, is a first-generation drug for the treatment of chronic hyperkalemia. However, because it releases sodium ions after exchanging potassium ions in the blood, the increased sodium load can exacerbate the volume overload in patients with hypertension, heart failure, or end-stage renal disease. Calcium polystyrene sulfonate, on the other hand, releases calcium rather than sodium after exchanging potassium in the blood. This has the advantage of not increasing sodium levels in the body while also providing calcium supplementation. Therefore, calcium polystyrene sulfonate is expected to become a superior alternative for the treatment of chronic hyperkalemia, offering patients improved therapeutic outcomes and quality of life.

[0003] Patent application publication number CN101091926A discloses a method for preparing calcium polystyrene sulfonate cation exchange resin. The method involves converting industrial-grade sodium polystyrene sulfonate resin, which has been treated with one or more of the processes described in the patent application, such as removal of free polystyrene, residual 1,2-dichloroethane, and bleaching, into calcium polystyrene sulfonate resin using a calcium ion-containing composition. The calcium ion-containing composition comprises calcium ions and their counterions, a complexing agent, a pH regulator, and water. The counterion is chloride ion, and the complexing agent is one or a combination of two or more of ethylenediaminetetraacetic acid, ethylenediaminetriaminepentaacetic acid, nitrilotriacetic acid, citric acid, and their calcium or sodium salts. The volume ratio of the calcium ion-containing composition to the resin is 2 to 9.

[0004] In this technology, when preparing polystyrene calcium sulfonate cation exchange resin, the complexing agent used is one or a combination of two or more agents selected from ethylenediaminetetraacetic acid, ethylenediaminetriaminepentaacetic acid, nitrilotriacetic acid, citric acid, and their calcium salts or sodium salts. Although these weak acids and bases and their calcium salts or sodium salts can form complexes with metal ions as complexing agents, their complexing ability for calcium ions is relatively weak. During the preparation of polystyrene calcium sulfonate cation exchange resin, they cannot effectively complex and guide calcium ions into the resin structure, thereby limiting the calcium loading rate in the polystyrene calcium sulfonate. Summary of the Invention

[0005] In order to increase the calcium loading rate in calcium polystyrene sulfonate, the present application provides calcium polystyrene sulfonate and a preparation method thereof.

[0006] In a first aspect, the present application provides a method for preparing calcium polystyrene sulfonate, which adopts the following technical solution:

[0007] A method for preparing calcium polystyrene sulfonate comprises the following steps:

[0008] S1: Mix sodium polystyrene sulfonate microspheres and zeolite aqueous dispersion at a mass ratio of 1:(3-5), heat to 40-60°C, mix for 3-5 hours, separate the solid and liquid, and wash to obtain primary sodium polystyrene sulfonate microspheres;

[0009] S2: Primary sodium polystyrene sulfonate microspheres are prepared into suspension 1, and suspension 1 and a calcium chloride solution with a mass fraction of 8% to 12% are introduced into a microchannel reactor at the same time. After reacting for 20 to 30 minutes, solid-liquid separation is performed, and the suspension is washed to prepare suspension 2. Suspension 2 and a calcium chloride solution with a mass fraction of 12% to 15% are introduced into a microchannel reactor at the same time. After reacting for 20 to 30 minutes, solid-liquid separation is performed, and the suspension is washed to prepare suspension 3. Suspension 3 and a calcium chloride solution with a mass fraction of 15% to 20% are introduced into a microchannel reactor at the same time. After reacting for 8 to 15 minutes, solid-liquid separation is performed, washed, dried, and crushed to obtain calcium polystyrene sulfonate;

[0010] The mass fraction of zeolite in the aqueous dispersion is 6% to 15%.

[0011] Preferably, the zeolite is 4A zeolite.

[0012] The beneficial effect lies in: by pre-treating the sodium polystyrene sulfonate microspheres with an aqueous zeolite dispersion, ion exchange occurs between the zeolite and the sodium polystyrene sulfonate microspheres, partially exchanging sodium ions on the microsphere surface. This creates a localized low-sodium environment on the microsphere surface, opening up more active sites for subsequent calcium ion adsorption. Furthermore, after the ion exchange, the chemical environment and charge distribution on the microsphere surface change, enhancing the activity of the surface sulfonate groups, making them more conducive to ion exchange with the subsequently added calcium ions.

[0013] Afterwards, calcium conversion is initiated using a low-concentration calcium chloride solution, which allows the calcium ions to slowly exchange with the sodium ions on the surface of the primary sodium polystyrene sulfonate microspheres. This helps avoid excessively vigorous exchange reactions due to high calcium ion concentrations, and also prevents amorphous precipitation caused by local oversaturation, making the exchange process more uniform and increasing the calcium content of the calcium polystyrene sulfonate microspheres and the stability of the product's performance. As the concentration of the calcium chloride solution gradually increases, the ion exchange reaction can be further promoted in a more complete direction, allowing more sodium ions to be replaced by calcium ions, further improving the calcium ion loading rate and yield in the product.

[0014] Preferably, the method for preparing the aqueous dispersion of zeolite comprises the following steps:

[0015] After dispersing polyethylene glycol in water, adding zeolite and mixing evenly, the product is obtained.

[0016] Preferably, the amount of polyethylene glycol used is 4% to 6% of the mass of the zeolite.

[0017] Preferably, the zeolite is 4A zeolite.

[0018] Preferably, the mass ratio of the sodium polystyrene sulfonate microspheres, the calcium chloride solution with a mass fraction of 8% to 12%, the calcium chloride solution with a mass fraction of 12% to 15%, and the calcium chloride solution with a mass fraction of 15% to 20% is 1:(5-7):(3-5):(2-4).

[0019] Preferably, in step S1, the washing is first performed with water for 3 to 5 times, and then with a calcium chloride solution with a mass fraction of 6% to 8% for 2 to 4 times.

[0020] The beneficial effect is: first washing with water 3 to 5 times can remove some water-soluble impurities on the surface of sodium polystyrene sulfonate microspheres, making the surface of the microspheres cleaner. After that, washing with a calcium chloride solution with a mass fraction of 6% to 8% for 2 to 4 times will form a partial calcification layer on the surface of the microspheres, which can neutralize excess negative charge and avoid complete saturation. During subsequent calcification, it can quickly penetrate the surface layer, drive internal sodium ion replacement, and improve the overall calcium ion loading rate.

[0021] Preferably, the sodium polystyrene sulfonate microspheres undergo the following pretreatment steps before use:

[0022] The sodium polystyrene sulfonate microspheres are sequentially washed with water, oxidized, acid washed, alcohol washed, and alkaline washed until neutral, and dried to obtain the microspheres.

[0023] Preferably, the oxidation adopts gradient oxidation, first washing with a sodium hypochlorite solution with a mass fraction of 0.3% to 0.5% for 10 to 20 minutes, then immersing in a sodium hypochlorite solution with a mass fraction of 0.2% to 0.4% for 20 to 40 minutes, and then solid-liquid separation and washing.

[0024] Preferably, the pickling adopts a two-stage pickling, first washing with a hydrochloric acid solution with a mass fraction of 4% to 6% for 15 to 30 minutes, then immersing in a hydrochloric acid solution with a mass fraction of 3% to 5% for 3 to 5 hours, solid-liquid separation, and washing.

[0025] Preferably, the alcohol washing is carried out by washing with ethanol, then soaking in ethanol for 6 to 8 hours, and then performing solid-liquid separation and washing.

[0026] Preferably, the alkali washing is performed with sodium hydroxide having a mass fraction of 4% to 6%, and then immersed in a sodium hydroxide solution having a mass fraction of 3% to 5% for 90 to 150 minutes.

[0027] The beneficial effect is that this method combines gradient oxidation and two-stage acid washing to construct a two-stage impurity removal system of "rapid oxidation-fine purification", which can not only more effectively remove impurities in the microspheres and maintain the original performance and structure of the microspheres, but also improve the pore structure of sodium polystyrene sulfonate microspheres, thereby increasing the subsequent calcium ion loading rate.

[0028] First, gradient oxidation, through treatment with sodium hypochlorite solutions of varying concentrations, can gradually oxidize impurities on the microsphere surface and decompose some organic impurities into smaller molecules, such as carbon dioxide and water, avoiding damage to the microsphere structure. While removing impurities, it also releases or reveals pores previously blocked or occupied by impurities, thereby improving the pore structure. This improved pore structure provides more access channels and binding sites for subsequent calcium ions, thereby increasing the calcium ion loading rate.

[0029] Secondly, a two-stage pickling process, using hydrochloric acid solutions of varying concentrations, more comprehensively removes residual impurities, including those produced by oxidation or other difficult-to-remove substances. This further removal of impurities clears the microspheres' pores, increasing their effective surface area and creating better conditions for calcium ion loading, thereby improving the calcium ion loading rate.

[0030] Finally, ethanol is used to displace water and form a protective film, inhibiting microsphere swelling or shrinkage and maintaining the integrity of the porous structure. This prevents the pore structure from being damaged during treatment and affecting calcium ion loading. Subsequently, sodium hydroxide is used to neutralize residual acidic groups, reducing electrostatic aggregation and improving the dispersion stability of the microspheres in the solution. Good dispersion allows the microspheres to more fully contact calcium ions, which helps improve the calcium ion loading efficiency and loading capacity.

[0031] Preferably, the zeolite undergoes the following pretreatment steps before use:

[0032] The zeolite is dispersed in ferric chloride solution, heated to 50-70°C, immersed and mixed for 5-7 hours, solid-liquid separation, washed, and dried to obtain the product.

[0033] The concentration of the ferric chloride solution is 0.1-0.3 mol / L.

[0034] Preferably, the mass volume ratio of the zeolite to the ferric chloride solution is 1 g: (5-10) ml.

[0035] The beneficial effect is that iron ions are loaded into the layered structure of the zeolite through ion exchange, replacing some sodium ion sites, increasing the exchange capacity for sodium ions in the sodium polystyrene sulfonate microspheres, and being able to more effectively reduce the sodium content in the sodium polystyrene sulfonate, creating favorable conditions for the subsequent reaction with calcium chloride. From the perspective of ion exchange equilibrium, there is an exchange driving force with sodium ions in the environment surrounding the microspheres, which prompts more sodium ions to be replaced from the sodium polystyrene sulfonate microspheres, reducing the shielding effect of sodium ions on the sulfonic acid groups. This makes the active sites of the sulfonic acid groups more exposed, making it easier to combine with calcium ions in subsequent reactions, ultimately increasing the calcium ion loading capacity.

[0036] Preferably, in step S2, tartaric acid is added to the calcium chloride solution for mixing before use, and the mass fraction of the tartaric acid in the calcium chloride solution is 0.1% to 0.3%.

[0037] By adopting the above technical solution, tartaric acid molecules can contact and complex with a small amount of free trivalent iron ions that may be present in the solution, preventing them from reacting unnecessarily with calcium polystyrene sulfonate, and avoiding the mixing of iron ion impurities into the product to affect the purity and performance of calcium polystyrene sulfonate. At the same time, when the tartaric acid-calcium ion chelate is close to the surface of sodium polystyrene sulfonate microspheres, it can more efficiently transfer calcium ions to the active sites on the surface of the microspheres compared to free calcium ions, thereby significantly improving the calcium loading rate. In addition, the chelation of tartaric acid and calcium ions can also effectively prevent the calcium ions in the solution from forming a precipitate, maintain the active state of calcium ions, increase the probability of their binding to the sulfonate ions on the surface of the microspheres, and promote the calcium transfer reaction to proceed more fully.

[0038] Preferably, in step S2, polyaspartic acid is added to the calcium chloride solution for mixing before use, and the mass fraction of the polyaspartic acid in the calcium chloride solution is 0.05% to 0.4%.

[0039] Beneficial Effects: Polyaspartic acid has a strong chelating ability for calcium ions, forming a relatively stable chelate. This helps evenly disperse calcium ions in the solution, promotes the full reaction between sodium polystyrene sulfonate and calcium chloride, and improves the conversion rate of calcium polystyrene sulfonate. Furthermore, the functional groups on the polyaspartic acid molecules may interact with those on the microsphere surface, further altering the surface properties and making them more conducive to calcium ion loading.

[0040] In a second aspect, the present application provides calcium polystyrene sulfonate prepared by the above-mentioned calcium polystyrene sulfonate preparation method.

[0041] In summary, this application has the following beneficial effects:

[0042] 1. The present application uses an aqueous dispersion of zeolite to pretreat sodium polystyrene sulfonate, which can replace some sodium ions through ion exchange, reduce the shielding effect of sodium ions on the sulfonic acid groups, and expose more active sites of the sulfonic acid groups, making them easier to combine with calcium ions in subsequent reactions, thereby increasing the calcium ion loading capacity; at the same time, calcium chloride is gradually converted from low concentration to high concentration to make the exchange uniform, which not only increases the calcium ion loading rate in calcium polystyrene sulfonate, but also improves product quality and performance consistency, and increases purity and yield.

[0043] 2. Before use, the polystyrene sulfonate sodium microspheres of this application are sequentially washed with water, gradient oxidation, two-stage acid washing, alcohol washing, and alkaline washing. Among them, the gradient oxidation achieves rapid oxidation, and the two-stage acid washing completes the fine purification, constructing a "rapid oxidation-fine purification" dual-stage impurity removal system. This system can not only more effectively remove more impurities in the microspheres and maintain the original performance and structure of the microspheres, but also release or expose pores originally blocked or occupied by impurities, providing more channels and binding sites for the subsequent entry of calcium ions, thereby increasing the calcium ion loading rate.

[0044] 3. The present application preferably uses ferric chloride to pretreat the zeolite. The iron ions enter the lattice structure of the zeolite through ion exchange, promoting ion exchange with the sodium polystyrene sulfonate microspheres, thereby replacing more sodium ions from the sodium polystyrene sulfonate microspheres, reducing the occupation of the sulfonic acid groups by sodium ions, making the sulfonic acid groups more easily combined with calcium ions, thereby increasing the calcium ion loading capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is the standard infrared spectrum of calcium polystyrene sulfonate;

[0046] Figure 2 This is the infrared spectrum of calcium polystyrene sulfonate in Example 1. DETAILED DESCRIPTION

[0047] The present application is further described in detail below with reference to the embodiments.

[0048] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0049] The particle size distribution of sodium polystyrene sulfonate microspheres is 0.3~0.8mm;

[0050] The particle size distribution of 4A zeolite is 1~10μm;

[0051] The elution rate of sodium hypochlorite solution is 5~10mL / min, the elution rate of hydrochloric acid solution is 10~15mL / min, the elution rate of sodium hydroxide is 8~12mL / min, the elution rate of purified water is 15~20mL / min, and the elution rate of ethanol is 8~12mL / min.

[0052] Example 1

[0053] This embodiment provides a method for preparing calcium polystyrene sulfonate, comprising the following steps:

[0054] S1: 100 g of sodium polystyrene sulfonate microspheres and 300 g of a 6% by mass aqueous dispersion of 4A zeolite were placed in a container, stirred and mixed uniformly, heated to 40°C, and stirred and mixed at a speed of 200 r / min for 5 h. The mixture was filtered, washed three times with purified water, and then washed twice with a 6% by mass calcium chloride solution to obtain primary sodium polystyrene sulfonate microspheres.

[0055] S2: The primary sodium polystyrene sulfonate microspheres were stirred and mixed with 100 g of purified water to obtain suspension one; suspension one and 500 g of 8% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 20 minutes, filtered, washed twice with purified water, and then stirred and mixed with 100 g of purified water to obtain suspension two; suspension two and 300 g of 12% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 20 minutes, filtered, washed twice with purified water, and then stirred and mixed with 100 g of purified water to obtain suspension three; suspension three and 200 g of 15% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 8 minutes, filtered, washed with purified water until the outlet conductivity was less than 40 us / cm, transferred to a blast drying oven, dried to constant weight at 60°C, and crushed to obtain calcium polystyrene sulfonate.

[0056] Among them, the temperature of the microchannel reactor is 40°C, the flow rate of suspension one is 2.0 mL / min, and the flow rate of 8% calcium chloride is 5.0 mL / min; the flow rate of suspension two is 2.0 mL / min, and the flow rate of 12% calcium chloride is 4.0 mL / min; the flow rate of suspension three is 3.0 mL / min, and the flow rate of 15% calcium chloride is 3.0 mL / min.

[0057] The preparation method of the aqueous dispersion of 4A zeolite comprises the following steps: stirring and mixing 0.72g of polyethylene glycol and 281.28g of purified water, then adding 18g of 4A zeolite, stirring and mixing at a speed of 800r / min, and obtaining the aqueous dispersion.

[0058] In step S1, the sodium polystyrene sulfonate microspheres undergo the following pretreatment steps before use:

[0059] Connect the purified water supply pipe to the bottom inlet of the glass column, then pre-mix 110g of sodium polystyrene sulfonate microspheres with 500g of purified water and transfer them into the glass column. Slowly open the purified water valve and control the purified water to rise at a rate of 1-2 cm per minute to reversely flush the sodium polystyrene sulfonate microspheres in the glass column. After washing for 3 minutes, connect the nitrogen pipe to the gas inlet at the bottom of the glass column, slowly open the high-purity nitrogen valve, and adjust the nitrogen flow rate so that the nitrogen forms a uniform and moderate bubble flow in the glass column. After continuing the air mixing for 5 minutes, filter to obtain the water-washed microspheres.

[0060] The washed microspheres were first rinsed with a 0.3% sodium hypochlorite solution for 20 minutes, then immersed in a 0.2% sodium hypochlorite solution for 40 minutes, filtered, rinsed with purified water for 10 minutes, first rinsed with a 4% hydrochloric acid solution for 30 minutes, then immersed in a 3% hydrochloric acid solution for 5 hours, filtered, rinsed with purified water until the effluent was neutral, rinsed with ethanol for 10 minutes, then immersed in ethanol for 6 hours, filtered, rinsed with purified water until there was no obvious ethanol smell, then rinsed with a 4% sodium hydroxide solution for 10 minutes, then immersed in a 3% sodium hydroxide solution for 150 minutes, washed with purified water until the effluent was neutral, filtered, transferred to a blast drying oven, and dried at 50°C to constant weight.

[0061] Example 2

[0062] This embodiment provides a method for preparing calcium polystyrene sulfonate, comprising the following steps:

[0063] S1: 100 g of sodium polystyrene sulfonate microspheres and 400 g of a 10% by mass 4A zeolite aqueous dispersion were placed in a container, stirred and mixed uniformly, heated to 50°C, and stirred and mixed at a speed of 200 r / min for 4 h. The mixture was filtered, washed four times with purified water, and then washed three times with a 7% by mass calcium chloride solution to obtain primary sodium polystyrene sulfonate microspheres.

[0064] S2: The primary sodium polystyrene sulfonate microspheres were stirred and mixed with 100 g of purified water to obtain suspension one; suspension one and 600 g of 10% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 25 minutes, filtered, washed twice with purified water, and then stirred and mixed with 100 g of purified water to obtain suspension two; suspension two and 400 g of 13% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 25 minutes, filtered, washed twice with purified water, and then stirred and mixed with 100 g of purified water to obtain suspension three; suspension three and 300 g of 17% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 12 minutes, filtered, washed with purified water until the outlet water conductivity was less than 40 us / cm, transferred to a blast drying oven, dried to constant weight at 60°C, and crushed to obtain calcium polystyrene sulfonate.

[0065] Among them, the temperature of the microchannel reactor is 50°C, the flow rate of suspension one is 2.0 mL / min, and the flow rate of 10% calcium chloride is 5.0 mL / min; the flow rate of suspension two is 2.0 mL / min, and the flow rate of 13% calcium chloride is 4.0 mL / min; the flow rate of suspension three is 3.0 mL / min, and the flow rate of 17% calcium chloride is 3.0 mL / min.

[0066] The preparation method of the aqueous dispersion of 4A zeolite comprises the following steps: stirring and mixing 2g of polyethylene glycol and 358g of purified water, then adding 40g of 4A zeolite, stirring and mixing at a speed of 800r / min, and obtaining the aqueous dispersion.

[0067] In step S1, the sodium polystyrene sulfonate microspheres undergo the following pretreatment steps before use:

[0068] Connect the purified water supply pipe to the bottom inlet of the glass column, then pre-mix 110g of sodium polystyrene sulfonate microspheres with 400g of purified water and transfer them into the glass column. Slowly open the purified water valve and control the purified water to rise at a rate of 1-2 cm per minute to reversely flush the sodium polystyrene sulfonate microspheres in the glass column. After washing for 5 minutes, connect the nitrogen pipe to the gas inlet at the bottom of the glass column, slowly open the high-purity nitrogen valve, adjust the nitrogen flow rate, so that the nitrogen forms a uniform and moderate bubble flow in the glass column. After continuing the air mixing for 10 minutes, filter to obtain the water-washed microspheres.

[0069] The washed microspheres were first rinsed with a 0.4% sodium hypochlorite solution by mass for 15 minutes, then immersed in a 0.3% sodium hypochlorite solution by mass for 30 minutes, filtered, rinsed with purified water for 15 minutes, first rinsed with a 5% hydrochloric acid solution by mass for 25 minutes, then immersed in a 4% hydrochloric acid solution by mass for 4 hours, filtered, rinsed with purified water until the effluent was neutral, rinsed with ethanol for 12 minutes, then immersed in ethanol for 7 hours, filtered, rinsed with purified water until there was no obvious ethanol smell, then rinsed with a 5% sodium hydroxide solution by mass for 8 minutes, then immersed in a 4% sodium hydroxide solution by mass for 120 minutes, washed with purified water until the effluent was neutral, filtered, transferred to a blast drying oven, and dried at 50°C to constant weight.

[0070] Example 3

[0071] This embodiment provides a method for preparing calcium polystyrene sulfonate, comprising the following steps:

[0072] S1: 100 g of sodium polystyrene sulfonate microspheres and 500 g of a 12% by mass 4A zeolite aqueous dispersion were placed in a container, stirred and mixed uniformly, heated to 60°C, and stirred and mixed at a speed of 200 r / min for 3 h. The mixture was filtered, washed with purified water 5 times, and then washed with 8% by mass calcium chloride solution 4 times to obtain primary sodium polystyrene sulfonate microspheres.

[0073] S2: The primary sodium polystyrene sulfonate microspheres were stirred and mixed with 100 g of purified water to obtain suspension one; the suspension one and 700 g of a 12% calcium chloride solution were simultaneously introduced into a microchannel reactor, calcified for 30 minutes, filtered, washed twice with purified water, and then stirred and mixed with 100 g of purified water to obtain suspension two; the suspension two and 500 g of a 15% calcium chloride solution were simultaneously introduced into a microchannel reactor, calcified for 30 minutes, filtered, washed twice with purified water, and then stirred and mixed with 100 g of purified water to obtain suspension three; the suspension three and 400 g of a 20% calcium chloride solution were simultaneously introduced into a microchannel reactor, calcified for 15 minutes, filtered, washed with purified water until the effluent conductivity was less than 40 us / cm, transferred to a blast drying oven, dried to constant weight at 60°C, and crushed to obtain calcium polystyrene sulfonate;

[0074] Among them, the temperature of the microchannel reactor is 60°C, the flow rate of suspension one is 2.0 mL / min, and the flow rate of 12% calcium chloride is 5.0 mL / min; the flow rate of suspension two is 2.0 mL / min, and the flow rate of 15% calcium chloride is 4.0 mL / min; the flow rate of suspension three is 3.0 mL / min, and the flow rate of 20% calcium chloride is 3.0 mL / min.

[0075] The preparation method of the aqueous dispersion of 4A zeolite comprises the following steps: stirring and mixing 3.6g of polyethylene glycol and 436.4g of purified water, then adding 60g of 4A zeolite, stirring and mixing at a speed of 800r / min, and obtaining the aqueous dispersion.

[0076] In step S1, the sodium polystyrene sulfonate microspheres undergo the following pretreatment steps before use:

[0077] Connect the purified water supply pipe to the bottom inlet of the glass column, then premix 110g of sodium polystyrene sulfonate microspheres with 300g of purified water and transfer them into the glass column. Slowly open the purified water valve and control the purified water to rise at a rate of 1-2 cm per minute to reversely flush the sodium polystyrene sulfonate microspheres in the glass column. After washing for 8 minutes, connect the nitrogen pipe to the gas inlet at the bottom of the glass column, slowly open the high-purity nitrogen valve, and adjust the nitrogen flow rate so that the nitrogen forms a uniform and moderate bubble flow in the glass column. After continuing the air mixing for 15 minutes, filter to obtain the water-washed microspheres.

[0078] The washed microspheres were first rinsed with a 0.4% sodium hypochlorite solution by mass for 15 minutes, then immersed in a 0.2% sodium hypochlorite solution by mass for 40 minutes, filtered, rinsed with purified water for 20 minutes, first rinsed with a 6% hydrochloric acid solution by mass for 15 minutes, then immersed in a 5% hydrochloric acid solution by mass for 3 hours, filtered, rinsed with purified water until the effluent was neutral, rinsed with ethanol for 15 minutes, then immersed in ethanol for 8 hours, filtered, rinsed with purified water until there was no obvious ethanol smell, then rinsed with a 6% sodium hydroxide solution by mass for 5 minutes, then immersed in a 5% sodium hydroxide solution by mass for 90 minutes, washed with purified water until the effluent was neutral, filtered, transferred to a blast drying oven, and dried at 50°C to constant weight.

[0079] Example 4

[0080] The difference between this embodiment and embodiment 3 is that:

[0081] 4A zeolite undergoes the following pretreatment steps before use:

[0082] 60 g of 4A zeolite was added to the reactor, followed by the addition of 300 ml of ferric chloride solution. The mixture was stirred at 800 r / min for 15 min to obtain a uniformly distributed suspension. The mixture was heated to 50° C. and stirred for 7 h. The suspension was centrifuged and washed four times with purified water. The suspension was then transferred to a blast drying oven at 70° C. and dried to constant weight.

[0083] In step S2, tartaric acid was added to the 12% by mass calcium chloride solution, the 15% by mass calcium chloride solution, and the 20% by mass calcium chloride solution before use, and the mass fraction of tartaric acid in the above calcium chloride solutions was 0.1%.

[0084] Wherein, calcium chloride solution is added to the tartaric acid before it is introduced into the microchannel reactor, and the mixture is stirred and mixed evenly.

[0085] Other details are the same as in Example 3.

[0086] Example 5

[0087] The difference between this embodiment and embodiment 4 is that:

[0088] The mass fraction of the aqueous dispersion of 4A zeolite is 15%.

[0089] The preparation method of the aqueous dispersion of 4A zeolite comprises the following steps: stirring and mixing 4.5g of polyethylene glycol and 420.5g of purified water, then adding 75g of 4A zeolite, stirring and mixing at a speed of 800r / min, and obtaining the dispersion.

[0090] 4A zeolite undergoes the following pretreatment steps before use:

[0091] 75 g of 4A zeolite was added to the reactor, followed by 750 ml of ferric chloride solution. The mixture was stirred at 800 r / min for 15 min to obtain a uniformly distributed suspension. The mixture was heated to 70° C. and stirred for 5 h. The suspension was centrifuged and washed four times with purified water. The suspension was then transferred to a blast drying oven at 70° C. and dried to constant weight.

[0092] In step S2, tartaric acid was added to the 12% by mass calcium chloride solution, the 15% by mass calcium chloride solution, and the 20% by mass calcium chloride solution before use, and the mass fraction of tartaric acid in the above calcium chloride solutions was 0.3%.

[0093] Other details are the same as in Example 4.

[0094] Example 6

[0095] The difference between this embodiment and embodiment 5 is that:

[0096] In step S2, polyaspartic acid is added to the 12% by mass calcium chloride solution, the 15% by mass calcium chloride solution, and the 20% by mass calcium chloride solution before use and stirred and mixed;

[0097] The mass fraction of polyaspartic acid in a 12% by mass calcium chloride solution is 0.05%, the mass fraction of polyaspartic acid in a 15% by mass calcium chloride solution is 0.15%, and the mass fraction of polyaspartic acid in a 20% by mass calcium chloride solution is 0.3%.

[0098] Other details are the same as in Example 5.

[0099] Example 7

[0100] The difference between this embodiment and embodiment 6 is that:

[0101] In step S2, polyaspartic acid is added to the 12% by mass calcium chloride solution, the 15% by mass calcium chloride solution, and the 20% by mass calcium chloride solution before use, and the mixture is stirred and mixed;

[0102] The mass fraction of polyaspartic acid in a 12% by mass calcium chloride solution is 0.1%, the mass fraction of polyaspartic acid in a 15% by mass calcium chloride solution is 0.2%, and the mass fraction of polyaspartic acid in a 20% by mass calcium chloride solution is 0.4%.

[0103] Other details are the same as in Example 6.

[0104] Comparative Example 1

[0105] This comparative example provides a method for preparing calcium polystyrene sulfonate, comprising the following steps:

[0106] S1: Sodium polystyrene sulfonate microspheres were stirred and mixed with 100 g of purified water to obtain suspension one; suspension one and 500 g of 8% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 20 minutes, filtered, washed twice with purified water, and then stirred and mixed with 100 g of purified water to obtain suspension two; suspension two and 300 g of 12% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 20 minutes, filtered, washed twice with purified water, and then stirred and mixed with 100 g of purified water to obtain suspension three; suspension three and 200 g of 15% calcium chloride solution were introduced into a microchannel reactor at the same time, calcified for 8 minutes, filtered, washed with purified water until the outlet water conductivity was less than 40 us / cm, transferred to a blast drying oven, dried to constant weight at 60°C, and crushed to obtain calcium polystyrene sulfonate.

[0107] Among them, the temperature of the microchannel reactor is 40°C, the flow rate of suspension one is 2.0 mL / min, and the flow rate of 5% calcium chloride is 5.0 mL / min; the flow rate of suspension two is 2.0 mL / min, and the flow rate of 15% calcium chloride is 4.0 mL / min; the flow rate of suspension three is 3.0 mL / min, and the flow rate of 20% calcium chloride is 3.0 mL / min.

[0108] In step S1, the sodium polystyrene sulfonate microspheres undergo the following pretreatment steps before use:

[0109] Connect the purified water supply pipe to the bottom inlet of the glass column, then pre-mix 110g of sodium polystyrene sulfonate microspheres with 500g of purified water and transfer them into the glass column. Slowly open the purified water valve and control the purified water to rise at a rate of 1-2 cm per minute to reversely flush the sodium polystyrene sulfonate microspheres in the glass column. After washing for 3 minutes, connect the nitrogen pipe to the gas inlet at the bottom of the glass column, slowly open the high-purity nitrogen valve, and adjust the nitrogen flow rate so that the nitrogen forms a uniform and moderate bubble flow in the glass column. After continuing the air mixing for 5 minutes, filter to obtain the water-washed microspheres.

[0110] The washed microspheres were first rinsed with a 0.2% sodium hypochlorite solution for 30 minutes, then immersed in a 0.1% sodium hypochlorite solution for 60 minutes, filtered, rinsed with purified water for 10 minutes, first rinsed with a 4% hydrochloric acid solution for 30 minutes, then immersed in a 3% hydrochloric acid solution for 5 hours, filtered, rinsed with purified water until the effluent was neutral, rinsed with ethanol for 10 minutes, then immersed in ethanol for 6 hours, filtered, rinsed with purified water until there was no obvious ethanol smell, then rinsed with a 4% sodium hydroxide solution for 10 minutes, then immersed in a 3% sodium hydroxide solution for 150 minutes, washed with purified water until the effluent was neutral, filtered, transferred to a blast drying oven, and dried at 50°C to constant weight.

[0111] Comparative Example 2

[0112] The difference between this comparative example and Example 1 is:

[0113] In step S1, 100 g of sodium polystyrene sulfonate microspheres and 300 g of a 6% by mass 4A zeolite aqueous dispersion were placed in a container, stirred and mixed uniformly, heated to 40° C., stirred and mixed at a speed of 200 r / min for 5 h, filtered, and washed 5 times with purified water to obtain primary sodium polystyrene sulfonate microspheres;

[0114] Other details are the same as in Example 1.

[0115] Comparative Example 3

[0116] The difference between this comparative example and Example 1 is:

[0117] In step S2, the primary sodium polystyrene sulfonate microspheres were stirred and mixed with 300 g of purified water to obtain a suspension, and the suspension and 1000 g of a 15% calcium chloride solution were simultaneously introduced into a microchannel reactor for calcification reaction for 48 minutes. The microspheres were filtered and washed twice with purified water until the effluent conductivity was less than 40 μS / cm. The microspheres were then transferred to a blast drying oven at 60°C and dried to constant weight, and pulverized to obtain calcium polystyrene sulfonate.

[0118] Other details are the same as in Example 1.

[0119] Comparative Example 4

[0120] The difference between this comparative example and Example 1 is:

[0121] In step S1, the sodium polystyrene sulfonate microspheres undergo the following pretreatment steps before use:

[0122] Connect the purified water supply pipe to the bottom inlet of the glass column, then pre-mix 110g of sodium polystyrene sulfonate microspheres with 500g of purified water and transfer them into the glass column. Slowly open the purified water valve and control the purified water to rise at a rate of 1-2 cm per minute to reversely flush the sodium polystyrene sulfonate microspheres in the glass column. After washing for 3 minutes, connect the nitrogen pipe to the gas inlet at the bottom of the glass column, slowly open the high-purity nitrogen valve, and adjust the nitrogen flow rate so that the nitrogen forms a uniform and moderate bubble flow in the glass column. After continuing the air mixing for 5 minutes, filter to obtain the water-washed microspheres.

[0123] The washed microspheres were rinsed with 0.25% sodium hypochlorite solution for 20 minutes, then immersed in 0.25% sodium hypochlorite solution for 40 minutes, filtered, rinsed with purified water for 10 minutes, first rinsed with 3.5% hydrochloric acid solution for 30 minutes, then immersed in 3.5% hydrochloric acid solution for 5 hours, filtered, rinsed with purified water until the effluent was neutral, rinsed with ethanol for 10 minutes, then immersed in ethanol for 6 hours, filtered, rinsed with purified water until there was no obvious ethanol smell, then rinsed with 3.5% sodium hydroxide solution for 10 minutes, then immersed in 3.5% sodium hydroxide solution for 150 minutes, washed with purified water until the effluent was neutral, filtered, transferred to a blast drying oven, and dried at 50°C to constant weight.

[0124] Other details are the same as in Example 1.

[0125] Performance testing

[0126] The calcium content of the calcium polystyrene sulfonate prepared in Examples 1-7 and Comparative Examples 1-4 was measured using EDTA titration, and the calcium loading rate was calculated for each sample. The exchange capacity of the calcium polystyrene sulfonate prepared in Examples 1-7 and Comparative Examples 1-4 in potassium chloride solution was recorded based on the ion exchange stoichiometry (potassium-calcium exchange ratio of 2:1) to obtain the potassium exchange capacity of each sample. Specific results are shown in Table 1. The molecular weight of potassium chloride is 74.55, and the molecular weight of potassium is 39.10.

[0127] Table 1 Performance test of calcium polystyrene sulfonate prepared in Examples 1 to 7 and Comparative Examples 1 to 4

[0128]

[0129] Figure 1 From the Japanese Pharmacopoeia, combined Figure 1~Figure 2 Analysis of Example 1 shows that:

[0130] The calcium polystyrene sulfonate prepared in Example 1 has similar absorption peak positions to the standard spectrum in multiple key wavenumber bands, such as 3000-3100 cm -1 The absorption peaks appearing near 1000-1200 cm can be attributed to the stretching vibration of CH on the benzene ring, indicating the presence of benzene ring structure in the sample; -1 The absorption peak at corresponds to the stretching vibration of SO in the sulfonic acid group, indicating that the sample has the structural characteristics of calcium sulfonate. These similar absorption peaks indicate that the main functional groups of the sample are consistent with those of the standard, and the infrared spectrum preliminarily proves that the sample is calcium polystyrene sulfonate.

[0131] Analysis of Example 1 and Comparative Examples 1-4 shows that pre-treating the sodium polystyrene sulfonate microspheres with 4A zeolite changes the chemical environment or microstructure of the microsphere surface, providing more active sites or more favorable binding modes for subsequent calcium ion loading, thereby improving the calcium loading rate. Carrying out the calcium transfer reaction in a gradient-increasing manner avoids drastic changes in ion concentration in the reaction system, allowing calcium ions to more evenly and stably bind to the sulfonate ions in the sodium polystyrene sulfonate, reducing precipitation or side reactions caused by excessive local ion concentration, and facilitating an increase in the calcium loading rate.

[0132] Analysis of Examples 1 to 3 shows that by optimizing the ratio of each component, the prepared calcium polystyrene sulfonate has a good calcium loading rate.

[0133] Analysis of Examples 3 to 7 shows that pretreating 4A zeolite with ferric chloride further alters the chemical environment or microstructure of the microsphere surface during subsequent pretreatment of sodium polystyrene sulfonate microspheres, providing more active sites or more favorable binding modes for subsequent calcium ion loading, thereby increasing the calcium loading rate. Adding tartaric acid and polyaspartic acid to the calcium chloride solution optimizes the environmental system for the calcium transfer reaction, synergizing with the effect of pretreating 4A zeolite with ferric chloride to further promote subsequent calcium ion loading.

[0134] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing calcium polystyrene sulfonate, characterized in that: The steps include: S1: Mix sodium polystyrene sulfonate microspheres and zeolite aqueous dispersion at a mass ratio of 1:(3-5), heat to 40-60°C, mix for 3-5 hours, separate the solid and liquid, and wash to obtain primary sodium polystyrene sulfonate microspheres; S2: Primary sodium polystyrene sulfonate microspheres are prepared into a suspension 1, and the suspension 1 and a calcium chloride solution with a mass fraction of 8% to 12% are introduced into a microchannel reactor simultaneously. After reacting for 20 to 30 minutes, the solid-liquid separation is carried out, and the suspension 2 is prepared after washing. The suspension 2 and a calcium chloride solution with a mass fraction of 12% to 15% are introduced into a microchannel reactor simultaneously. After reacting for 20 to 30 minutes, the solid-liquid separation is carried out, and the suspension 3 is prepared after washing. The suspension 3 and a calcium chloride solution with a mass fraction of 15% to 20% are introduced into a microchannel reactor simultaneously. After reacting for 8 to 15 minutes, the solid-liquid separation is carried out, washing, drying, and crushing are carried out to obtain calcium polystyrene sulfonate; The mass fraction of zeolite in the aqueous dispersion is 6% to 15%; The sodium polystyrene sulfonate microspheres undergo the following pretreatment steps before use: The polystyrene sulfonate sodium microspheres are sequentially washed with water, oxidized, acid-washed, alcohol-washed, and alkaline-washed, washed until neutral, and dried to obtain the microspheres; the oxidation adopts gradient oxidation, first washed with a sodium hypochlorite solution with a mass fraction of 0.3% to 0.5% for 10 to 20 minutes, then immersed in a sodium hypochlorite solution with a mass fraction of 0.2% to 0.4% for 20 to 40 minutes, solid-liquid separation, and washing; In step S1, the washing is first performed with water for 3 to 5 times, and then with a calcium chloride solution having a mass fraction of 6% to 8% for 2 to 4 times; the zeolite undergoes the following pretreatment steps before use: the zeolite is dispersed in a ferric chloride solution; In step S2, tartaric acid or polyaspartic acid is added to the calcium chloride solution before use and mixed.

2. The method for preparing calcium polystyrene sulfonate according to claim 1, wherein The mass ratio of the sodium polystyrene sulfonate microspheres, the calcium chloride solution with a mass fraction of 8% to 12%, the calcium chloride solution with a mass fraction of 12% to 15%, and the calcium chloride solution with a mass fraction of 15% to 20% is 1:(5-7):(3-5):(2-4).

3. The method for preparing calcium polystyrene sulfonate according to claim 1, wherein The zeolite undergoes the following pretreatment steps before use: Disperse zeolite in ferric chloride solution, heat to 50-70°C, soak and mix for 5-7 hours, separate solid and liquid, wash, and dry to obtain the zeolite. The concentration of the ferric chloride solution is 0.1-0.3 mol / L.

4. The method for preparing calcium polystyrene sulfonate according to claim 3, wherein The mass volume ratio of the zeolite to the ferric chloride solution is 1 g: (5-10) ml.

5. The method for preparing calcium polystyrene sulfonate according to claim 3, wherein The mass fraction of the tartaric acid in the calcium chloride solution is 0.1% to 0.3%.

6. The method for preparing calcium polystyrene sulfonate according to claim 1, wherein The mass fraction of the polyaspartic acid in the calcium chloride solution is 0.05% to 0.4%.

7. Calcium polystyrene sulfonate obtained by the method for preparing calcium polystyrene sulfonate according to any one of claims 1 to 6.

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