Method for purifying high-structure carbon black

Abstract

The invention provides a high-structure carbon black purification method, and belongs to the field of carbon material treatment. The method comprises the step of enabling a metal compound and a metal simple substance in the high-structure carbon black to enter an electrolyte in the form of ions by utilizing acid and electrolysis mixing treatment. And the treated electrolyte-carbon black mixed system utilizes a strong electric field and anion and cation exchange membranes to enable metal ions to directionally move to be separated from carbon black, so that the purification effect is achieved. The method is simple in step and high in metal impurity removal rate.

Description

Technical Field

[0001] The invention belongs to the field of carbon material processing, and in particular relates to a method for purifying high-structure carbon black. Background Art

[0002] Carbon black is an important carbon material, especially high-structure carbon black, which has excellent electrical conductivity and is widely used in electronic components and dry batteries. However, some application fields have high requirements for the metal impurity content in carbon black. Although the conventional acid treatment and high-temperature treatment methods can reduce the metal content in carbon black, due to the particularity of the structure of high-structure carbon black, some metal impurities are embedded in the high-structure carbon black aggregates and are completely covered by them, which makes it impossible to effectively remove this part of the metal impurities during the treatment process. At the same time, the carbon black after acid treatment needs to be separated from the solid-liquid mixed system. During the separation process, due to the adsorption of the high-structure carbon black surface, some metal ions in the solution are adsorbed on the surface of the high-structure carbon black, and the metal ions cannot be completely separated from the high-structure carbon black. Summary of the invention

[0003] The present invention aims at solving the problems in the prior art and provides a method for purifying high-structure carbon black. The method has simple steps and a high removal rate of metal impurities.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A method for purifying high-structure carbon black comprises the following steps:

[0006] Step 1: Mix the raw carbon black with the acid solution and perform an electrolytic reaction;

[0007] Step 2: placing the solid-liquid mixed system after the reaction in step 1 in a uniform parallel electric field, applying ultrasound to the solid-liquid mixed system, and after a certain period of treatment, inserting anionic and cationic membranes into the system to treat the solid-liquid mixed system;

[0008] Step 3: After step 2, the solid part is separated and dried.

[0009] Mix carbon black with acid solution. + The metal impurities in the carbon black undergo redox reactions, so that the metal impurities enter the solution in the form of ions. However, due to the complexity of the structure of high-structure carbon black, some metal impurities embedded in the high-structure carbon black may be difficult to contact with the acid, resulting in incomplete acid treatment reaction. Figure 1 The treatment method shown allows the metal impurities to enter the solution system more completely.

[0010] like Figure 1As shown, the electrolysis method is used to place the carbon black-acid mixed system into the electrolytic cell, and the DC power supply is turned on. Since the high-structure carbon black itself has good conductivity, the following reactions occur in the electrolytic cell:

[0011] Me————Me +

[0012]

[0013] Through the above reaction, the metal impurities embedded in the carbon black can be completely converted into ions and enter the solution, solving the problem that some metal impurities cannot be effectively oxidized into ions.

[0014] Although the metal impurities enter the solution system completely in the form of ions, there are still certain problems in the subsequent treatment, causing some metal impurities to adhere to the carbon black: In the conventional filtration separation method of solid-liquid system, due to the structural complexity and diversity of the pore structure of high-structure carbon black, the metal ions will be adsorbed to the surface of the carbon black during the filtration process. Despite multiple filtrations, it is still difficult to completely remove the metal ions attached to the surface through conventional filtration. In order to solve this problem, before filtration, use the following method: Figure 2 The method shown is to further treat the carbon black-solution mixed system after electrolysis treatment.

[0015] like Figure 2 As shown, ultrasound is applied to the mixed system (ultrasound can desorb metal cations adsorbed on the surface of carbon black), and a uniform electric field is applied externally to make the metal cations in the mixed system move toward the negative pole of the electric field. After a period of time, an anion membrane is inserted on the left side of the mixed system and a cation membrane is inserted on the right side (after the electric field and ultrasound are removed, it is ensured that the metal cations will not diffuse back into the mixed system so that the metal cations will attach to the surface of carbon black again). After this treatment, the mixed solution no longer contains metal ion impurities, and the purified high-structure carbon black can be obtained by filtering and drying the mixed system.

[0016] Furthermore, the acid in step 1 is an oxidizing acid, and its concentration is 10wt%-50wt%, preferably 20wt%-30wt%.

[0017] Furthermore, the acid described in step 1 is nitric acid or sulfuric acid.

[0018] Furthermore, the mass / volume ratio of the carbon black to the acid solution in step 1 is 100g:1L-3L.

[0019] Furthermore, in step 1, the carbon black and the acid solution are mixed and then heated and stirred.

[0020] Furthermore, the heating temperature is 0°C-100°C, preferably 50°C-70°C; the stirring speed is 50r / min-500r / min, preferably 200r / min-350r / min; and the stirring time is 0.5h-4h, preferably 1h-2h.

[0021] Furthermore, the power source for the electrolysis reaction in step 1 is a DC power source or an AC power source, and the voltage is 5V-50V, preferably 10V-30V.

[0022] Furthermore, the electrode for the electrolysis reaction in step 1 is a platinum electrode, and the electrolytic solution is an electrolyte solution containing oxidizing ions.

[0023] Furthermore, the electrolytic solution of the electrolysis reaction in step 1 is a nitrate ion solution.

[0024] Furthermore, the electrolysis reaction time in step 1 is 0.5h-4h, preferably 1h-2h.

[0025] Furthermore, the electric field strength of the electric field in step 2 is 5V / m-100V / m, preferably 40V / m-80V / m.

[0026] Furthermore, the ultrasonic power density in step 2 is 0.3 W / cm 2 -0.4W / cm 2 .

[0027] Furthermore, the time of the electric field and ultrasonic treatment in step 2 is 0.5h-4h, preferably 2h-3h.

[0028] Furthermore, after the electric field and ultrasonic treatment in step 2 is completed, the anion membrane is placed on the negative electrode side of the electric field, and the cationic membrane is placed on the positive electrode side of the electric field.

[0029] Furthermore, the method for separating the solid in step 3 adopts a filter press method or a suction filtration method.

[0030] The present invention also provides high-structure carbon black obtained after purification according to the method of the present invention, wherein the total metal impurity content in the high-structure carbon black is less than 30 ppm; further, the total metal impurity content is less than 20 ppm.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. Due to the excellent conductivity of high-structure carbon black, the present invention uses electrolysis to treat high-structure carbon black, which can effectively ensure that the metal impurities in the entire structural system of high-structure carbon black can be converted into ionic form and enter the solid-liquid mixing system.

[0033] 2. The coordinated treatment of electric field, ultrasonic wave, anion unidirectional membrane and cation exchange membrane can effectively separate the metal ions in the solid-liquid system from the carbon black, thus preventing the metal ions from adhering to the surface of the high-structure carbon black again during the filtration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of electrolysis in step 1 of the present invention.

[0035] Figure 2 This is a processing schematic diagram of step 2 of the present invention. DETAILED DESCRIPTION

[0036] The technical scheme in the embodiment of the present invention will be clearly and completely described below. Obviously, the described embodiment is only a part of the embodiment of the present invention, rather than all the embodiments. Based on the embodiment in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. In addition, it is worth noting that the raw materials involved in the present invention are all common commercial products unless otherwise specified.

[0037] Example 1

[0038] A method for purifying high-structure carbon black comprises the following steps:

[0039] Step 1: Mix 100g of high-structure carbon black with 2L of 25wt% HNO3 solution, and stir at 60°C and 300r / min for 1h. Transfer the mixed solution to an electrolytic cell, use a 30V DC power supply, platinum electrodes as positive and negative electrodes, and nitrate ion solution as electrolyte for electrolysis, and the electrolysis reaction time is 1h.

[0040] Step 2: Transfer the solid-liquid mixed system after the reaction in step 1 to a uniform parallel electric field with an electric field strength of 50 V / m and apply a power density of 0.35 W / cm 2 After 3 hours of reaction, the anion membrane is placed on the negative electrode side of the electric field, the cation membrane is placed on the positive electrode side of the electric field, and the solid in the middle part of the anion and cation membranes is taken out.

[0041] Step 3: The solid obtained in step 2 is filtered and then dried.

[0042] The total metal impurity content (total content of chromium, cadmium, lead, cobalt, zinc, iron and copper) of the high structure carbon black before treatment was measured to be 5137 ppm, and the total metal impurity content (total content of chromium, cadmium, lead, cobalt, zinc, iron and copper) after treatment was measured to be 18 ppm.

[0043] Example 2

[0044] The DC power supply voltage in step 1 of the embodiment is reduced to 10V, and the other steps and conditions remain unchanged. The total metal impurity content (total content of chromium, cadmium, lead, cobalt, zinc, iron and copper) of the treated high-structure carbon black is 25ppm.

[0045] Example 3

[0046] The electric field strength of the uniform parallel electric field in step 2 of the embodiment is increased to 80 V / m, and the other steps and conditions remain unchanged. The total metal impurity content (total content of chromium, cadmium, lead, cobalt, zinc, iron and copper) of the high-structure carbon black after treatment is 19 ppm.

[0047] Comparative Example 1

[0048] Step 1: Mix 100g of high-structure carbon black with 2L of 25wt% HNO3 solution, and stir at 60°C and 300r / min for 1h. Transfer the mixed solution to an electrolytic cell, use a 30V DC power supply, platinum electrodes as positive and negative electrodes, and nitrate ion solution as electrolyte for electrolysis, and the electrolysis reaction time is 1h.

[0049] Step 2: Apply a power density of 0.35 W / cm to the solid-liquid mixed system after the reaction in step 1 is completed. 2 After 3 h of ultrasonic treatment, the carbon black filter cake was obtained by filtration.

[0050] Step 3: Wash the carbon black filter cake from step 2 with deionized water for three times, filter press and dry.

[0051] The total metal impurity content (total content of chromium, cadmium, lead, cobalt, zinc, iron and copper) of the treated high-structure carbon black is 124 ppm.

[0052] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for purifying high-structure carbon black, comprising the following steps: Step 1: Mix the raw carbon black with the acid solution and perform an electrolytic reaction; Step 2: placing the solid-liquid mixed system after the reaction in step 1 in a uniform parallel electric field, applying ultrasound to the solid-liquid mixed system, and after a certain period of treatment, inserting anionic and cationic membranes into the system to treat the solid-liquid mixed system; Step 3: After step 2, the solid part is separated and dried.

2. The method according to claim 1, characterized in that: The acid described in step 1 is an oxidizing acid, preferably nitric acid or sulfuric acid; the concentration of the acid solution is 10wt%-50wt%, preferably 20wt%-30wt%.

3. The method according to claim 1, characterized in that: In step 1, the carbon black and the acid solution are mixed and then heated and stirred; preferably, the heating temperature is 0°C-100°C, preferably 50°C-70°C; the stirring speed is 50r / min-500r / min, preferably 200r / min-350r / min; the stirring time is 0.5h-4h, preferably 1h-2h.

4. The method according to claim 1, characterized in that: The power source for the electrolysis reaction in step 1 is a DC power supply or an AC power supply, and the voltage is 5V-50V, preferably 10V-30V; the time for the electrolysis reaction in step 1 is 0.5h-4h, preferably 1h-2h.

5. The method according to claim 1, characterized in that: The electrode for the electrolytic reaction in step 1 is a platinum electrode, and the electrolytic solution is an electrolyte solution containing oxidizing ions, preferably a nitrate ion solution.

6. The method according to claim 1, characterized in that: The electric field strength of the electric field in step 2 is 5V / m-100V / m, preferably 40V / m-80V / m.

7. The method according to claim 1, characterized in that: The ultrasonic power density in step 2 is 0.3W / cm 2 -0.4W / cm 2 The time of the electric field and ultrasonic treatment in step 2 is 0.5h-4h, preferably 2h-3h.

8. The method according to claim 1, characterized in that: In step 2, the anion membrane is placed on the negative electrode side of the electric field, and the cation membrane is placed on the positive electrode side of the electric field.

9. A high-structure carbon black, wherein the total metal impurity content of the high-structure carbon black is less than 30 ppm, preferably, the total metal impurity content is less than 20 ppm.

10. The high structure carbon black according to claim 9, characterized in that: The high structure carbon black is purified according to the method according to any one of claims 1-8.

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