Impurity removal process of high-purity electronic-grade barium carbonate

Abstract

The invention discloses an impurity removal process of high-purity electronic-grade barium carbonate, which comprises the following steps: firstly, primarily purifying a raw material barium chloride, then respectively preparing the purified raw material barium chloride and ammonium bicarbonate into solutions, and then mixing the two solutions for precipitation reaction to prepare a crude product barium carbonate; the method is characterized in that the crude product is dispersed in an aqueous solution containing special modified biochar for adsorption washing so as to deeply remove impurities, and finally solid-liquid separation and drying treatment are performed to obtain the target product. The method is mild in process condition, simple and convenient to operate, green and environment-friendly, can be used for stably preparing the electronic-grade barium carbonate meeting the harsh standard at lower cost, and has remarkable economic benefits and industrial application prospects.

Description

Technical Field

[0001] This invention relates to the field of barium carbonate technology, and more specifically to a process for removing impurities from high-purity electronic-grade barium carbonate. Background Technology

[0002] Barium carbonate (BaCO3) is an important inorganic fine chemical product, playing an indispensable role in high-tech fields due to its excellent dielectric, piezoelectric, and ferroelectric properties. Particularly in the electronics industry, high-purity, ultrafine electronic-grade barium carbonate is a core material for manufacturing key electronic components such as multilayer ceramic capacitors (MLCCs), positive temperature coefficient (PTC) thermistors, varistors, electro-optical components, and high-grade optical glass. These high-end applications place extremely stringent requirements on the purity of barium carbonate and its physical properties, including particle morphology and size distribution. The presence of even trace impurities can severely degrade the electrical performance and reliability of the final electronic components.

[0003] Currently, the main industrial method for preparing barium carbonate is precipitation, which involves reacting soluble barium salts (such as barium chloride and barium nitrate) with carbonates (such as sodium carbonate and ammonium bicarbonate) in aqueous solution to form barium carbonate precipitate. However, industrial raw materials often contain concomitant elements with very similar properties, such as strontium (Sr) and calcium (Ca). These impurity ions are highly susceptible to co-precipitation during the precipitation process due to their similar ionic radii, being trapped or substituted into the barium carbonate crystal lattice to form a solid solution. Furthermore, other impurity ions such as iron and chloride may also be present in the reaction system.

[0004] To remove these harmful impurities, existing technologies typically employ methods such as acid washing, multiple recrystallizations, or the addition of complexing agents for purification. CN105712390A discloses a room-temperature synthesis method for electronic-grade high-purity barium carbonate, including barium chloride dissolution and purification; barium carbonate synthesis; and barium carbonate washing and purification. This invention synthesizes barium carbonate by dropwise addition of purified barium chloride solution to food-grade ammonium bicarbonate solution at room temperature, reducing the number of barium carbonate washing steps to three, and lowering the synthesis temperature of high-purity barium carbonate from the traditional 60°C to room temperature. While ensuring that the synthesized barium carbonate meets the requirements for electronic-grade high purity, it saves energy, reduces emissions, and lowers costs.

[0005] However, these methods generally suffer from problems such as complex processes, long production cycles, high energy consumption, and low yields. For example, simple water washing or acid washing is difficult to effectively remove impurity ions that have entered the crystal lattice; repeated recrystallization purification processes are not only costly but also cumbersome to operate; while conventional adsorbents such as activated carbon, although they have a certain ability to remove impurities, often have poor adsorption selectivity, limited capacity, and may introduce the risk of secondary pollution.

[0006] Therefore, developing a simple, cost-controllable, environmentally friendly process that can efficiently remove stubborn impurities such as strontium and calcium, thereby stably preparing high-purity barium carbonate that meets the requirements of the electronics industry, has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a process for removing impurities from high-purity electronic-grade barium carbonate. This invention deeply integrates precise precipitation reaction control with efficient adsorption purification, using biochar as a substrate to construct a functionalized surface with synergistic adsorption effect, thereby achieving highly efficient targeted removal of impurities.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A purification process for high-purity electronic-grade barium carbonate includes the following steps:

[0010] (1) Add barium chloride to deionized water, stir and mix, filter to obtain refined barium chloride;

[0011] Preferably, in step (1), the stirring and mixing conditions are 50-100℃ for 30-60 min; the ratio of barium chloride to deionized water is 1g:5-10mL.

[0012] (2) Add refined barium chloride to deionized water and stir to dissolve it to obtain a barium chloride solution;

[0013] Preferably, in step (2), the concentration of the barium chloride solution is 0.1–0.5 mol / L;

[0014] (3) Add ammonium bicarbonate to deionized water, stir to dissolve, and obtain ammonium bicarbonate solution;

[0015] Preferably, in step (3), the concentration of the ammonium bicarbonate solution is 0.1 to 0.5 mol / L.

[0016] (4) Add barium chloride solution dropwise to ammonium bicarbonate solution, adjust the pH of the system, stir the reaction, centrifuge the product to obtain crude barium carbonate;

[0017] Preferably, in step (4), the temperature is controlled at 3-8°C when the barium chloride solution is added dropwise, and the pH of the system is adjusted to 8-9 with ammonia water; the stirring reaction conditions are 40-120 r / min and 5-15°C for 30-90 min.

[0018] (5) The crude barium carbonate is dispersed in deionized water containing modified biochar, stirred, washed and dried to obtain the high-purity electronic-grade barium carbonate.

[0019] Preferably, in step (5), the ratio of crude barium carbonate, modified biochar, and deionized water is 10g: 3-6g: 100-150mL;

[0020] Preferably, in step (5), the stirring and washing conditions are stirring and washing at room temperature for 30 to 90 minutes, followed by washing with deionized water until the chloride ion content is less than 30 ppm; the drying conditions are drying at 100 to 110°C for 3 to 5 hours.

[0021] Preferably, in step (5), the modified biochar is prepared by the following method steps:

[0022] a. Disperse the biochar in a hydrogen peroxide solution, stir to react, centrifuge, wash and dry the product to obtain pretreated biochar;

[0023] Hydrogen peroxide pretreatment of biochar: This process oxidizes and breaks the carbon-carbon bonds on the biochar surface or performs electrophilic substitution on aromatic rings, thereby generating a large number of hydroxyl (-OH) and carboxyl (-COOH) groups. This process greatly increases the surface polarity and chemically reactive sites of the biochar, laying the foundation for subsequent surface modification.

[0024] Preferably, in step a, the ratio of biochar to hydrogen peroxide solution is 10g:80-100mL; and the concentration of hydrogen peroxide solution is 10-20wt%.

[0025] Preferably, in step a, the stirring reaction conditions are 35–50°C for 12–24 hours.

[0026] b. Disperse the pretreated biochar in Tris-HCl buffer, then add dopamine hydrochloride, stir the reaction, filter, wash and dry the product to obtain polydopamine biochar;

[0027] Dopamine surface polymerization: Under weakly alkaline conditions, the catechol structure in the dopamine molecule is oxidized to a quinone structure, and further undergoes intermolecular Michael addition and Schiff base reactions, rapidly polymerizing into polydopamine (PDA) with strong adhesion. This polymer spontaneously deposits on the surface of pretreated biochar, forming a uniform coating layer rich in amino (-NH2) and phenolic hydroxyl groups, fundamentally altering the surface chemical properties of the biochar.

[0028] Preferably, in step b, the ratio of pretreated biochar, Tris-HCl buffer, and dopamine hydrochloride is 10g: 200-500mL: 2-5g; the concentration of Tris-HCl buffer is 10-20mmol / L, and the pH is 8-8.5.

[0029] Preferably, in step b, the stirring reaction conditions are 25–40°C for 6–12 hours.

[0030] c. Add ethylenediamine disuccinic acid to PBS buffer, then add EDC and NHS, stir to activate, then disperse polydopamine biochar in the activation solution, continue stirring the reaction, filter, wash and dry the product to obtain modified biochar.

[0031] EDDS functionalization: First, EDC acts as a dehydrating agent to activate the carboxyl group on the ethylenediamine disuccinic acid (EDDS) molecule, forming a highly reactive O-acylisourea intermediate. Subsequently, NHS reacts with this intermediate to generate a relatively more stable NHS active ester. When amino-rich polydopamine biochar is added, its amino groups (-NH2) act as nucleophiles, attacking the carbonyl carbon of the NHS active ester, ultimately forming a stable amide bond (-CO-NH-), thus successfully and firmly grafting the EDDS molecule onto the biochar surface in a covalent manner.

[0032] Preferably, in step c, the ratio of ethylenediamine disuccinic acid, PBS buffer, EDC, NHS, and polydopamine biochar is 3-6g: 100-150mL: 1-2g: 0.5-1g: 10g; and the pH of the PBS buffer is 7.0-7.5.

[0033] Preferably, in step c, the stirring activation conditions are: stirring activation at room temperature for 30–60 min; and the stirring reaction conditions are: stirring reaction at 20–35°C for 8–24 h.

[0034] Preferably, the prepared high-purity electronic-grade barium carbonate product has a barium carbonate content >99.5%, a calcium content <140 ppm, a strontium content <160 ppm, an iron content <50 ppm, and a D content <140 ppm. 50 The size is 1–5 μm.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. This invention proposes a purification process for high-purity electronic-grade barium carbonate. First, by dissolving and filtering industrial-grade barium chloride raw material at a specific temperature, the difference in solubility between barium chloride and common impurity salts (such as strontium chloride and calcium chloride) in water is utilized to effectively remove some soluble and insoluble impurities, providing a higher-purity material basis for subsequent reactions. Second, the precipitation reaction is strictly controlled at low temperature, dropping rate, and pH value, which is conducive to the formation of barium carbonate with uniform particles and complete crystals, reducing the co-precipitation and encapsulation of impurities from the source. Finally, this process creatively uses specially modified biochar to stir and wash the crude product as a key deep purification step, which can efficiently adsorb and remove residual trace impurity ions in the crude product, ensuring that the final product meets the stringent standards of high-purity electronic grade.

[0037] 2. This invention provides a modified biochar. First, the biochar substrate itself possesses a large specific surface area and abundant pore structure, providing excellent physical adsorption capacity. On top of this, the carboxyl and hydroxyl groups introduced by the first step of hydrogen peroxide treatment, along with the polydopamine layer coated in the second step, give the material surface an overall negative charge, enabling efficient adsorption of positively charged metal impurity ions through electrostatic attraction. More importantly, a significant synergistic enhancement effect is generated between polydopamine and grafted ethylenediamine disuccinic acid (EDDS): the polydopamine layer not only provides abundant surface complexation sites but also acts as an ideal functional bridge, firmly anchoring EDDS; while EDDS, as a powerful multidentate chelating agent, has densely distributed amino and carboxyl groups that can form extremely stable cyclic structures with metal ions. Therefore, this modified biochar integrates four functions: physical adsorption (biochar substrate), electrostatic attraction (PDA and oxygen-containing functional groups), surface complexation (PDA), and strong chelation (EDDS). It has a strong ability to remove impurity ions, a large capacity, and a strong binding, thus enabling deep purification of barium carbonate and obtaining high-purity products that meet the requirements of the electronics industry. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some schematic diagrams of certain embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a SEM image of barium carbonate prepared in Example 1 of the present invention. Detailed Implementation

[0040] 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. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0041] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0042] Biochar was prepared by pyrolyzing wheat straw at 500℃ for 8 hours.

[0043] A purification process for high-purity electronic-grade barium carbonate includes the following steps:

[0044] (1) Add 1g of barium chloride to 5-10mL of deionized water, stir and mix at 50-100℃ for 30-60min, filter, and obtain purified barium chloride;

[0045] (2) Add purified barium chloride to deionized water and stir to dissolve, to obtain a 0.1-0.5 mol / L barium chloride solution;

[0046] (3) Add ammonium bicarbonate to deionized water, stir to dissolve, and obtain a 0.1-0.5 mol / L ammonium bicarbonate solution;

[0047] (4) At 3-8℃, barium chloride solution is slowly added dropwise to ammonium bicarbonate solution. The pH of the system is adjusted to 8-9 with ammonia water. The mixture is stirred at 40-120 r / min and 5-15℃ for 30-90 min. The product is then centrifuged to obtain crude barium carbonate.

[0048] (5) Disperse 10g of biochar in 80-100mL of 10-20wt% hydrogen peroxide solution, stir and react at 35-50℃ for 12-24h, centrifuge the product, wash with deionized water until neutral, and dry to obtain pretreated biochar.

[0049] (6) Disperse 10g of pretreated biochar in 200-500mL Tris-HCl buffer (10-20mmol / L, pH=8-8.5), then add 2-5g of dopamine hydrochloride, stir and react at 25-40℃ for 6-12h, filter, wash and dry the product to obtain polydopamine biochar;

[0050] (7) Add 3-6 g of ethylenediamine disuccinic acid to 100-150 mL of PBS buffer (pH = 7.0-7.5), then add 1-2 g of EDC and 0.5-1 g of NHS, stir and activate at room temperature for 30-60 min, then disperse 10 g of polydopamine biochar in the activation solution, and continue to stir and react at 20-35 °C for 8-24 h. Filter, wash and dry the product to obtain modified biochar.

[0051] (8) Disperse 10g of crude barium carbonate into 100-150mL of deionized water containing 3-6g of modified biochar, stir and wash at room temperature for 30-90min, then wash with deionized water until the chloride ion content is less than 30ppm, and dry at 100-110℃ for 3-5h to obtain the high-purity electronic-grade barium carbonate.

[0052] The present invention will be further described below through specific embodiments.

[0053] Example 1

[0054] A purification process for high-purity electronic-grade barium carbonate includes the following steps:

[0055] (1) Add 1g of barium chloride to 10mL of deionized water, stir and mix at 80℃ for 45min, filter, and obtain purified barium chloride;

[0056] (2) Add purified barium chloride to deionized water and stir to dissolve, to obtain a 0.3 mol / L barium chloride solution;

[0057] (3) Add ammonium bicarbonate to deionized water and stir to dissolve, to obtain a 0.3 mol / L ammonium bicarbonate solution;

[0058] (4) At 5℃, barium chloride solution was slowly added dropwise to ammonium bicarbonate solution. The pH of the system was adjusted to 8.5 with ammonia water. The mixture was stirred at 100 r / min and 10℃ for 60 min. The product was centrifuged to obtain crude barium carbonate.

[0059] (5) Disperse 10g of biochar in 100mL of 15wt% hydrogen peroxide solution, stir and react at 50℃ for 12h, centrifuge the product, wash with deionized water until neutral, and dry to obtain pretreated biochar.

[0060] (6) Disperse 10g of pretreated biochar in 400mL Tris-HCl buffer (15mmol / L, pH=8.0), then add 5g of dopamine hydrochloride, stir at 40℃ for 6h, filter, wash and dry the product to obtain polydopamine biochar;

[0061] (7) Add 6g of ethylenediamine disuccinic acid to 120mL of PBS buffer (pH=7.0), then add 2g of EDC and 1g of NHS, stir and activate at room temperature for 60min, then disperse 10g of polydopamine biochar in the activation solution, continue to stir and react at 35℃ for 8h, filter, wash and dry the product to obtain modified biochar;

[0062] (8) Disperse 10g of crude barium carbonate into 150mL of deionized water containing 6g of modified biochar, stir and wash at room temperature for 90min, then wash with deionized water until the chloride ion content is less than 30ppm, and dry at 105℃ for 4h to obtain the high-purity electronic grade barium carbonate.

[0063] Example 2

[0064] A purification process for high-purity electronic-grade barium carbonate includes the following steps:

[0065] (1) Add 1g of barium chloride to 10mL of deionized water, stir and mix at 80℃ for 45min, filter, and obtain purified barium chloride;

[0066] (2) Add purified barium chloride to deionized water and stir to dissolve, to obtain a 0.3 mol / L barium chloride solution;

[0067] (3) Add ammonium bicarbonate to deionized water and stir to dissolve, to obtain a 0.3 mol / L ammonium bicarbonate solution;

[0068] (4) At 5℃, barium chloride solution was slowly added dropwise to ammonium bicarbonate solution. The pH of the system was adjusted to 8.5 with ammonia water. The mixture was stirred at 100 r / min and 10℃ for 60 min. The product was centrifuged to obtain crude barium carbonate.

[0069] (5) Disperse 10g of biochar in 100mL of 15wt% hydrogen peroxide solution, stir and react at 45℃ for 16h, centrifuge the product, wash with deionized water until neutral, and dry to obtain pretreated biochar.

[0070] (6) Disperse 10g of pretreated biochar in 400mL Tris-HCl buffer (15mmol / L, pH=8.0), then add 4g of dopamine hydrochloride, stir and react at 35℃ for 8h, filter, wash and dry the product to obtain polydopamine biochar;

[0071] (7) Add 5g of ethylenediamine disuccinic acid to 120mL of PBS buffer (pH=7.0), then add 1.5g of EDC and 0.8g of NHS, stir and activate at room temperature for 50min, then disperse 10g of polydopamine biochar in the activation solution, continue to stir and react at 30℃ for 12h, filter, wash and dry the product to obtain modified biochar;

[0072] (8) Disperse 10g of crude barium carbonate into 150mL of deionized water containing 5g of modified biochar, stir and wash at room temperature for 70min, then wash with deionized water until the chloride ion content is less than 30ppm, and dry at 105℃ for 4h to obtain the high-purity electronic grade barium carbonate.

[0073] Example 3

[0074] A purification process for high-purity electronic-grade barium carbonate includes the following steps:

[0075] (1) Add 1g of barium chloride to 10mL of deionized water, stir and mix at 80℃ for 45min, filter, and obtain purified barium chloride;

[0076] (2) Add purified barium chloride to deionized water and stir to dissolve, to obtain a 0.3 mol / L barium chloride solution;

[0077] (3) Add ammonium bicarbonate to deionized water and stir to dissolve, to obtain a 0.3 mol / L ammonium bicarbonate solution;

[0078] (4) At 5℃, barium chloride solution was slowly added dropwise to ammonium bicarbonate solution. The pH of the system was adjusted to 8.5 with ammonia water. The mixture was stirred at 100 r / min and 10℃ for 60 min. The product was centrifuged to obtain crude barium carbonate.

[0079] (5) Disperse 10g of biochar in 100mL of 15wt% hydrogen peroxide solution, stir and react at 40℃ for 20h, centrifuge the product, wash with deionized water until neutral, and dry to obtain pretreated biochar.

[0080] (6) Disperse 10g of pretreated biochar in 400mL Tris-HCl buffer (15mmol / L, pH=8.0), then add 3g of dopamine hydrochloride, stir and react at 30℃ for 10h, filter, wash and dry the product to obtain polydopamine biochar;

[0081] (7) Add 4g of ethylenediamine disuccinic acid to 120mL of PBS buffer (pH=7.0), then add 1.5g of EDC and 0.8g of NHS, stir and activate at room temperature for 40min, then disperse 10g of polydopamine biochar in the activation solution, continue to stir and react at 25℃ for 20h, filter, wash and dry the product to obtain modified biochar;

[0082] (8) Disperse 10g of crude barium carbonate into 150mL of deionized water containing 4g of modified biochar, stir and wash at room temperature for 50min, then wash with deionized water until the chloride ion content is less than 30ppm, and dry at 105℃ for 4h to obtain the high-purity electronic grade barium carbonate.

[0083] Example 4

[0084] A purification process for high-purity electronic-grade barium carbonate includes the following steps:

[0085] (1) Add 1g of barium chloride to 10mL of deionized water, stir and mix at 80℃ for 45min, filter, and obtain purified barium chloride;

[0086] (2) Add purified barium chloride to deionized water and stir to dissolve, to obtain a 0.3 mol / L barium chloride solution;

[0087] (3) Add ammonium bicarbonate to deionized water and stir to dissolve, to obtain a 0.3 mol / L ammonium bicarbonate solution;

[0088] (4) At 5℃, barium chloride solution was slowly added dropwise to ammonium bicarbonate solution. The pH of the system was adjusted to 8.5 with ammonia water. The mixture was stirred at 100 r / min and 10℃ for 60 min. The product was centrifuged to obtain crude barium carbonate.

[0089] (5) Disperse 10g of biochar in 100mL of 15wt% hydrogen peroxide solution, stir and react at 50℃ for 12h, centrifuge the product, wash with deionized water until neutral, and dry to obtain pretreated biochar.

[0090] (6) Disperse 10g of pretreated biochar in 400mL Tris-HCl buffer (15mmol / L, pH=8.0), then add 2g of dopamine hydrochloride, stir and react at 25℃ for 12h, filter, wash and dry the product to obtain polydopamine biochar;

[0091] (7) Add 3g of ethylenediamine disuccinic acid to 120mL of PBS buffer (pH=7.0), then add 1g of EDC and 0.5g of NHS, stir and activate at room temperature for 30min, then disperse 10g of polydopamine biochar in the activation solution, continue to stir and react at 20℃ for 24h, filter, wash and dry the product to obtain modified biochar;

[0092] (8) Disperse 10g of crude barium carbonate into 150mL of deionized water containing 3g of modified biochar, stir and wash at room temperature for 30min, then wash with deionized water until the chloride ion content is less than 30ppm, and dry at 105℃ for 4h to obtain the high-purity electronic grade barium carbonate.

[0093] Comparative Example 1

[0094] A process for removing impurities from barium carbonate includes the following steps:

[0095] (1) Add 1g of barium chloride to 10mL of deionized water, stir and mix at 80℃ for 45min, filter, and obtain purified barium chloride;

[0096] (2) Add purified barium chloride to deionized water and stir to dissolve, to obtain a 0.3 mol / L barium chloride solution;

[0097] (3) Add ammonium bicarbonate to deionized water and stir to dissolve, to obtain a 0.3 mol / L ammonium bicarbonate solution;

[0098] (4) At 5℃, barium chloride solution was slowly added dropwise to ammonium bicarbonate solution. The pH of the system was adjusted to 8.5 with ammonia water. The mixture was stirred at 100 r / min and 10℃ for 60 min. The product was centrifuged to obtain crude barium carbonate.

[0099] (5) Disperse 10g of biochar in 100mL of 15wt% hydrogen peroxide solution, stir and react at 50℃ for 12h, centrifuge the product, wash with deionized water until neutral, and dry to obtain pretreated biochar.

[0100] (6) Disperse 10g of pretreated biochar in 400mL Tris-HCl buffer (15mmol / L, pH=8.0), then add 5g of dopamine hydrochloride, stir at 40℃ for 6h, filter, wash and dry the product to obtain polydopamine biochar;

[0101] (7) Disperse 10g of crude barium carbonate into 150mL of deionized water containing 3.75g of polydopamine biochar and 2.25g of ethylenediamine disuccinic acid, stir and wash at room temperature for 90min, then wash with deionized water until the chloride ion content is less than 30ppm, and dry at 105℃ for 4h to obtain the barium carbonate.

[0102] Comparative Example 2

[0103] A process for removing impurities from barium carbonate includes the following steps:

[0104] (1) Add 1g of barium chloride to 10mL of deionized water, stir and mix at 80℃ for 45min, filter, and obtain purified barium chloride;

[0105] (2) Add purified barium chloride to deionized water and stir to dissolve, to obtain a 0.3 mol / L barium chloride solution;

[0106] (3) Add ammonium bicarbonate to deionized water and stir to dissolve, to obtain a 0.3 mol / L ammonium bicarbonate solution;

[0107] (4) At 5℃, barium chloride solution was slowly added dropwise to ammonium bicarbonate solution. The pH of the system was adjusted to 8.5 with ammonia water. The mixture was stirred at 100 r / min and 10℃ for 60 min. The product was centrifuged to obtain crude barium carbonate.

[0108] (5) Disperse 10g of biochar in 100mL of 15wt% hydrogen peroxide solution, stir and react at 50℃ for 12h, centrifuge the product, wash with deionized water until neutral, and dry to obtain pretreated biochar.

[0109] (6) Disperse 10g of crude barium carbonate into 150mL of deionized water containing 4g of pretreated biochar and 2g of dopamine hydrochloride, stir and wash at room temperature for 90min, then wash with deionized water until the chloride ion content is less than 30ppm, and dry at 105℃ for 4h to obtain the barium carbonate.

[0110] The barium carbonate samples prepared in Examples 1-4 and Comparative Examples 1-2 were analyzed and detected by ICP method. The specific data are shown in Table 1.

[0111] Table 1. Barium carbonate analysis results

[0112]

[0113] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for removing impurities from high-purity electronic-grade barium carbonate, characterized in that, Includes the following steps: (1) Add barium chloride to deionized water, stir and mix, filter to obtain refined barium chloride; (2) Add refined barium chloride to deionized water and stir to dissolve it to obtain a barium chloride solution; (3) Add ammonium bicarbonate to deionized water, stir to dissolve, and obtain ammonium bicarbonate solution; (4) Add barium chloride solution dropwise to ammonium bicarbonate solution, adjust the pH of the system, stir the reaction, centrifuge the product to obtain crude barium carbonate; (5) The crude barium carbonate is dispersed in deionized water containing modified biochar, stirred, washed and dried to obtain the high-purity electronic-grade barium carbonate.

2. The impurity removal process according to claim 1, characterized in that, In step (1), the stirring and mixing conditions are 50-100℃ for 30-60 minutes; the ratio of barium chloride to deionized water is 1g:5-10mL.

3. The impurity removal process according to claim 1, characterized in that, In step (2), the concentration of barium chloride solution is 0.1–0.5 mol / L; in step (3), the concentration of ammonium bicarbonate solution is 0.1–0.5 mol / L.

4. The impurity removal process according to claim 1, characterized in that, In step (4), the temperature is controlled at 3-8℃ when the barium chloride solution is added dropwise, and the pH of the system is adjusted to 8-9 with ammonia water; the stirring reaction conditions are 40-120 r / min and 5-15℃ for 30-90 min.

5. The impurity removal process according to claim 1, characterized in that, In step (5), the ratio of crude barium carbonate, modified biochar, and deionized water is 10g:3-6g:100-150mL; the stirring and washing conditions are stirring and washing at room temperature for 30-90min, followed by washing with deionized water until the chloride ion content is less than 30ppm; the drying conditions are drying at 100-110℃ for 3-5h.

6. The impurity removal process according to claim 1, characterized in that, In step (5), the modified biochar is prepared by the following method steps: a. Disperse the biochar in a hydrogen peroxide solution, stir to react, centrifuge, wash and dry the product to obtain pretreated biochar; b. Disperse the pretreated biochar in Tris-HCl buffer, then add dopamine hydrochloride, stir the reaction, filter, wash and dry the product to obtain polydopamine biochar; c. Add ethylenediamine disuccinic acid to PBS buffer, then add EDC and NHS, stir to activate, then disperse polydopamine biochar in the activation solution, continue stirring the reaction, filter, wash and dry the product to obtain modified biochar.

7. The impurity removal process according to claim 6, characterized in that, In step a, the ratio of biochar to hydrogen peroxide solution is 10g:80-100mL; the concentration of hydrogen peroxide solution is 10-20wt%; and the stirring reaction conditions are 35-50℃ for 12-24h.

8. The impurity removal process according to claim 6, characterized in that, In step b, the ratio of pretreated biochar, Tris-HCl buffer, and dopamine hydrochloride is 10g: 200-500mL: 2-5g; the concentration of Tris-HCl buffer is 10-20mmol / L, and the pH is 8-8.5; the reaction conditions are stirring at 25-40℃ for 6-12h.

9. The impurity removal process according to claim 6, characterized in that, In step c, the ratio of ethylenediamine disuccinic acid, PBS buffer, EDC, NHS, and polydopamine biochar is 3–6 g: 100–150 mL: 1–2 g: 0.5–1 g: 10 g; the pH of the PBS buffer is 7.0–7.5; the activation conditions are: stirring at room temperature for 30–60 min; and the reaction conditions are: stirring at 20–35 °C for 8–24 h.

10. The impurity removal method according to claim 1, characterized in that, The high-purity electronic-grade barium carbonate product obtained has a barium carbonate content >99.5%, calcium content <140ppm, strontium content <160ppm, iron content <50ppm, and D... 50 The size is 1–5 μm.

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