Method for secondary extraction of bromine using primary bromine extraction waste liquid

Abstract

The present invention discloses a method for secondary extraction of bromine using primary bromine extraction waste liquid. The method comprises the following processing steps: S1 constructing an electrolytic facility; S2 starting the electrolytic facility and performing electrolytic oxidation treatment; S3 heating the primary bromine extraction waste liquid during electrolytic oxidation; S4 separating and treating the mixed steam generated at the platinum electrode by condensation, collecting the liquid formed by condensation, and recharging the gas into the primary bromine extraction waste liquid; S5 collecting H2 generated at the graphite electrode as a hydrogen source for reuse; S6 testing the Br in the anolyte by turbidimetry ‑ When the concentration of Br ‑ When the concentration of is no longer reduced, the electrolysis facility is shut down. The present invention establishes a segmented bromine recovery system, combines electrolytic oxidation to form bromine with Cl2 replacement of bromine, improves the recovery efficiency of bromine, and Cl2 is obtained by electrolysis, and a Cl2 recharge mode is used to further extract bromine, without the need for a blow-out tower and an absorption tower, thereby reducing the recovery cost of bromine.

Description

Technical Field

[0001] The invention relates to the technical field of bromine extraction, in particular to a method for secondary extraction of bromine using primary bromine extraction waste liquid. Background Art

[0002] The chemical formula of bromine is Br2, with a melting point of -7.2℃ and a boiling point of 58.78℃. It is a dark red-brown liquid with a pungent odor. It is slightly soluble in water and easily soluble in solvents such as ethanol, ether, benzene, chloroform, carbon disulfide and hydrochloric acid. Bromine is the only non-metallic element that is liquid at room temperature. It is an important chemical raw material and is widely used in flame retardants, fire extinguishing agents, refrigerants, photosensitive materials, medicines, pesticides and oil fields. It is packaged in acid-resistant ceramic jars or glass bottles, and the jar (bottle) mouth is sealed with wax or gypsum.

[0003] Referring to the invention patent with application number 200710014116.0, a new process for extracting bromine from waste liquid after primary bromine extraction is known. The process flow is summarized as follows: when brine passes through the pipeline, the bromide ions in the brine in the pipeline are oxidized by the added chlorine gas, and then the brine is sprayed into the blow-out tower from top to bottom. The tower uses a fan to blow air from bottom to top, so that the free bromine in the brine is resolved to form bromine air. The bromine air enters the absorption tower and reacts with the added sulfur dioxide and water to form hydrobromic acid. The hydrobromic acid is distilled to obtain bromine. However, with the development of bromine extraction technology, the current bromine extraction process has an extraction rate of 85% to 90%. Therefore, after primary bromine extraction, the bromide ion content in the waste liquid after bromine extraction is very small. The aforementioned patent still uses the mode of filling Cl2 for oxidation, which has little effect and uses the blow-out tower and the absorption tower to recover bromine, which is more cumbersome and increases the recovery cost of bromine. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for secondary extraction of bromine using primary bromine extraction waste liquid to improve the recovery efficiency of bromine and reduce the recovery cost of bromine.

[0005] The method for secondary extraction of bromine using primary bromine extraction waste liquid comprises the following processing steps:

[0006] S1 uses graphite electrode as cathode and platinum electrode as anode to construct electrolysis facilities;

[0007] The electrolysis facility comprises an electrolytic cell A and an electrolytic cell B, wherein the platinum electrode is located in the electrolytic cell A, the graphite electrode is located in the electrolytic cell B, the electrolytic cell A contains a primary bromine extraction waste liquid, and the electrolytic cell B contains a cathode electrolyte;

[0008] S2 starts the electrolysis facility to carry out electrolytic oxidation treatment;

[0009] While S3 is electrolytically oxidizing, the primary bromine extraction waste liquid is heated;

[0010] S4 separates the mixed steam generated at the platinum electrode by condensation, collects the liquid formed by condensation, and refills the gas into the primary bromine extraction waste liquid;

[0011] S5 collects H2 generated at the graphite electrode for reuse as a hydrogen source;

[0012] S6 Detection of Br in the anolyte by turbidimetry - When the concentration of Br - When the concentration no longer decreases, the electrolysis facility is shut down.

[0013] Preferably, the cathode electrolyte is ethylene carbonate, propylene carbonate, diethyl carbonate or maleic acid; a salt bridge is provided between the electrolytic cell A and the electrolytic cell B. In the present invention, the salt bridge is used as an ion channel for conduction, and the positive and negative ions pass through the salt bridge to balance the charges of the positive and negative electrodes. During electrolysis, the anode loses electrons and the anion gains electrons. As the electrolysis proceeds, charge imbalance occurs. At this time, the ions are transported through the channel provided by the salt bridge to rebalance the charges of the positive and negative electrodes, thereby ensuring the stability of the electrolysis process.

[0014] Preferably, the method for preparing the salt bridge is specifically performed as follows: agar is placed in a container filled with distilled water, heated in a water bath at 95-100° C. until the agar is completely dissolved, KCl is added while stirring until the mixture is evenly mixed, the mixture is added to a glass curved tube, and the mixture is allowed to stand until it condenses to obtain the salt bridge.

[0015] Furthermore, the mass volume ratio of agar to distilled water is 1:95-98, and the ratio of agar to KCl is 1:9-11.

[0016] Preferably, the working parameters of the electrolysis facility are: voltage 3~6V, current density 0.05~0.1A / cm². In the present invention, this voltage range and current density range are selected to ensure the efficiency and safety of the electrolysis process. In the electrolytic oxidation treatment, the anode reaction is: 2Br - -2e=Br2,2Cl - -2e=Cl2; cathode reaction is: 2H + +2e=H2.

[0017] Preferably, the heating temperature of the primary bromine extraction waste liquid is 55-60° C. In the present invention, the primary bromine extraction waste liquid is heated to evaporate the bromine generated by electrolysis.

[0018] Further, Br2 and Cl2 form the mixed steam, and the temperature of the condensation treatment is 1-10°C. In the present invention, bromine is changed from gaseous to liquid by condensation so as to be separated from Cl2, and bromine in the bromine extraction liquid is replaced by Cl2 backfilling, thereby further extracting bromine. The reaction mechanism of Cl2 and the primary bromine extraction waste liquid is Cl2+2Br - =Br2+2Cl - .

[0019] Furthermore, the electrolysis facility further comprises:

[0020] A bromine collection structure, comprising a drainage cover covered on the electrolytic cell A, a condenser, a conduit for connecting the drainage cover and the condenser, a bromine collection bottle, and a connecting pipe for connecting the bromine collection bottle and the condenser;

[0021] A Cl2 reflux pipe is fixedly installed through a side wall corresponding to the connecting pipe; and a heating sleeve, which is fixedly mounted on the electrolytic cell A.

[0022] Preferably, the conduit is fixedly connected to the outlet end of the drainage hood, the air inlet end of the condenser is arranged obliquely upward, the bromine collection bottle is located at a position on the corresponding side of the electrolytic cell A, and the lower end of the connecting pipe is inserted into the bromine collection bottle. In the present invention, the bromine in the mixed steam is condensed to form a liquid, thereby achieving the separation of Br2 and Cl2.

[0023] Preferably, the air inlet end of the Cl2 reflux pipe is located above the bromine collection bottle, and the air outlet end of the Cl2 reflux pipe extends into the primary bromine extraction liquid contained in the electrolytic cell A. The air inlet end of the Cl2 reflux pipe is located above the bromine collection bottle, and the air outlet end of the Cl2 reflux pipe extends into the bromine extraction liquid contained in the electrolytic cell where the platinum electrode is located. In the present invention, Cl2 is introduced into the bromine extraction liquid through the Cl2 reflux pipe, thereby replacing the bromine in the bromine extraction liquid. The reaction principle is Cl2+2Br - =Br2+2Cl - The Cl2 recharge mode is used to further extract bromine, and the Cl2 is obtained by electrolysis and can be reused. The entire Cl2 reflow process is carried out in the channel and is directly charged into the bromine extraction liquid for reaction, which has little pollution to the environment and high operation safety.

[0024] The heating bushing is filled with a resistance wire, and the working temperature of the heating bushing is 60° C. In the present invention, the heating bushing is arranged to heat the bromine extraction waste liquid, so that the bromine generated by electrolysis evaporates, and the mixed gas (Br2+Cl2) flows directionally into the bromine collection structure for further treatment.

[0025] Compared with the prior art, the beneficial effects of the present invention are: a segmented bromine recovery system is established, and the electrolytic oxidation to form bromine and the Cl2 replacement of bromine are combined, thereby improving the bromine recovery efficiency, and the Cl2 is obtained by electrolysis, and the Cl2 recharging mode is used to further extract bromine, without the need for a blow-out tower and an absorption tower, thereby reducing the bromine recovery cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure shows a flow chart of a method for secondary extraction of bromine using primary bromine extraction waste liquid provided by the present invention.

[0027] Figure 2 Shown is a schematic structural diagram of an electrolysis facility provided in Example 3 of the present invention.

[0028] 1. Drainage hood; 2. Catheter; 3. Condenser; 4. Connecting pipe; 5. Bromine collection bottle; 6. Cl2 reflux pipe; 7. Heating sleeve.

[0029] The above description of the main component symbols is combined with the accompanying drawings and specific implementation methods to further illustrate the present invention in detail. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Additional aspects and advantages of the present invention will be given in part in the following description, and will become apparent from the following description, or will be understood through the practice of the present invention. It should be understood that the following description is only used to explain the present invention and is not intended to limit the present invention.

[0031] The specific embodiments of the present invention are described in detail below.

[0032] Example 1

[0033] This embodiment provides a method for secondary extraction of bromine using primary bromine extraction waste liquid, which comprises the following processing steps:

[0034] S1 uses a graphite electrode as a cathode and a platinum electrode as an anode to construct an electrolysis facility. The electrolysis facility includes an electrolytic cell A and an electrolytic cell B, wherein the platinum electrode is located in the electrolytic cell A, the graphite electrode is located in the electrolytic cell B, the electrolytic cell A contains a primary bromine extraction waste liquid, and the electrolytic cell B contains ethylene carbonate.

[0035] A salt bridge is provided between the electrolytic cell A and the electrolytic cell B. The specific operation of the preparation method of the salt bridge is as follows: put agar into a container filled with distilled water, heat it in a water bath at 98°C until the agar is completely dissolved, add KCl while stirring until it is evenly mixed, add the mixed solution into a glass curved tube, and let it stand until the mixed solution condenses to obtain the salt bridge. The mass volume ratio of agar to distilled water is 1:98, and the ratio of agar to KCl is 1:11. Ions are transported through the channel provided by the salt bridge, and the salt bridge plays a role in balancing the positive and negative charges.

[0036] S2 starts the electrolysis facility to carry out electrolytic oxidation treatment.

[0037] The primary bromine extraction waste liquid is used as the anolyte for electrolytic oxidation to achieve the purpose of secondary extraction of bromine. The specific recovery mechanism is as follows: After the electrolysis starts, Br in the primary bromine extraction waste liquid - and Cl - Loss of electrons at the anode 2Br - -2e=Br2,2Cl - -2e=Cl2, and becomes Br2 and Cl2, H + Get electrons at the cathode 2H + +2e=H2, and it becomes H2 and escapes. The working parameters of the electrolysis facility are: voltage 5V, current density 0.05A / cm².

[0038] While S3 is electrolytically oxidizing, the primary bromine extraction waste liquid is heated to evaporate the bromine generated by electrolysis. The heating temperature is 55°C.

[0039] S4 uses condensation to separate the mixed steam generated at the platinum electrode, collects the liquid formed by condensation, and Br2 and Cl2 form the mixed steam. The temperature of the condensation treatment is 10°C. Through condensation, bromine is changed from gas to liquid so as to be separated from Cl2. Cl2 is recharged into the primary bromine extraction waste liquid to continue to participate in the following reaction: Cl2+2Br - =Br2+2Cl - , displacing the bromine in the bromine extraction solution, thereby further extracting bromine.

[0040] S5 collects H2 generated at the graphite electrode for reuse as a hydrogen source;

[0041] S6 Detection of Br in the anolyte by turbidimetry - When the concentration of Br - When the concentration no longer decreases, it indicates that the bromine in the primary bromine extraction waste liquid has been completely extracted. At this time, the electrolysis facility is closed and the electrolysis is ended.

[0042] Example 2

[0043] This embodiment provides a method for secondary extraction of bromine using primary bromine extraction waste liquid, which comprises the following processing steps:

[0044] S1 uses a graphite electrode as a cathode and a platinum electrode as an anode to construct an electrolysis facility. The electrolysis facility includes an electrolytic cell A and an electrolytic cell B, wherein the platinum electrode is located in the electrolytic cell A, the graphite electrode is located in the electrolytic cell B, the electrolytic cell A contains a primary bromine extraction waste liquid, and the electrolytic cell B contains maleic acid.

[0045] A salt bridge is provided between the electrolytic cell A and the electrolytic cell B. The specific operation of the preparation method of the salt bridge is as follows: put agar into a container filled with distilled water, heat it in a water bath at 100°C until the agar is completely dissolved, add KCl while stirring until it is evenly mixed, add the mixed solution into a glass curved tube, and let it stand until the mixed solution condenses to obtain the salt bridge. The mass volume ratio of agar to distilled water is 1:97, and the ratio of agar to KCl is 1:10. Ions are transported through the channel provided by the salt bridge, and the salt bridge plays a role in balancing the positive and negative charges.

[0046] S2 starts the electrolysis facility to carry out electrolytic oxidation treatment.

[0047] The primary bromine extraction waste liquid is used as the anolyte for electrolytic oxidation to achieve the purpose of secondary extraction of bromine. The specific recovery mechanism is as follows: After the electrolysis starts, Br in the primary bromine extraction waste liquid - and Cl - Loss of electrons at the anode 2Br - -2e=Br2,2Cl - -2e=Cl2, and becomes Br2 and Cl2, H + Get electrons at the cathode 2H + +2e=H2, and it becomes H2 and escapes. The working parameters of the electrolysis facility are: voltage 6V, current density 0.1A / cm².

[0048] While S3 is electrolytically oxidizing, the primary bromine extraction waste liquid is heated to evaporate the bromine generated by electrolysis, and the heating temperature is 60°C.

[0049] S4 uses condensation to separate the mixed steam generated at the platinum electrode, collects the liquid formed by condensation, and Br2 and Cl2 form the mixed steam. The temperature of the condensation treatment is 5°C. Through condensation, bromine is changed from gas to liquid so as to be separated from Cl2. Cl2 is recharged into the primary bromine extraction waste liquid to continue to participate in the following reaction: Cl2+2Br - =Br2+2Cl - , displacing the bromine in the bromine extraction solution, thereby further extracting bromine.

[0050] S5 collects H2 generated at the graphite electrode for reuse as a hydrogen source;

[0051] S6 Detection of Br in the anolyte by turbidimetry - When the concentration of Br - When the concentration no longer decreases, it indicates that the bromine in the primary bromine extraction waste liquid has been completely extracted. At this time, the electrolysis facility is closed and the electrolysis is ended.

[0052] Example 3

[0053] See also Figure 2 This embodiment provides an electrolytic device for bromine recovery, which is applied to the method for secondary extraction of bromine using primary bromine extraction waste liquid as described in Example 1 or Example 2. The electrolytic device includes an electrolytic cell A, an electrolytic cell B, a salt bridge installed between the electrolytic cell A and the electrolytic cell B, a graphite electrode, a platinum electrode, a bromine collection structure, a Cl2 reflux pipe 6 fixedly installed through the corresponding side wall of the connecting pipe 4, and a heating sleeve 7 fixedly sleeved on the electrolytic cell A.

[0054] The platinum electrode is installed in electrolytic cell A, which contains bromine extraction liquid, and 3 / 4 of the platinum electrode is submerged in the bromine extraction liquid. The graphite electrode is installed in electrolytic cell B, which contains cathode electrolyte, and 3 / 4 of the graphite electrode is submerged in the cathode electrolyte. It should be noted that this embodiment adopts an electrolysis mode in which anode oxidation and cathode reduction are separated. Therefore, after H2 is generated at the graphite electrode, it flows in a directed manner through a flow guide structure (not shown) for subsequent collection, and the collected H2 is reused as a hydrogen source.

[0055] The bromine collection structure includes a drainage cover 1 covering the electrolytic cell A, a condenser 3, a conduit 2 for connecting the drainage cover 1 and the condenser 3, a bromine collection bottle 5, and a connecting pipe 4 for connecting the bromine collection bottle 5 and the condenser 3.

[0056] It should be noted that, in order to facilitate wiring, a cable groove (not shown) is provided on the drainage hood 1 to accommodate the wires connected to the platinum electrode, which will not be described in detail here. The conduit 2 is fixedly connected to the air outlet end of the drainage hood 1, and 5°C water flows in the water-cooling chamber of the condenser 3. The air inlet end of the condenser 3 is arranged upwardly and tilted, and the bromine collection bottle 5 is located at the corresponding side of the electrolytic cell A, and the lower end of the connecting pipe 4 is inserted into the bromine collection bottle 5. In this embodiment, the bromine in the mixed steam is condensed to form a liquid, thereby achieving the separation of Br2 and Cl2.

[0057] The air inlet end of the Cl2 reflux pipe 6 is located above the bromine collecting bottle 5, and the air outlet end of the Cl2 reflux pipe 6 extends into the bromine extraction liquid. In this embodiment, Cl2 is introduced into the bromine extraction liquid through the Cl2 reflux pipe 6, thereby replacing the bromine in the bromine extraction liquid. The reaction principle is Cl2+2Br - =Br2+2Cl- The Cl2 recharge mode is used to further extract bromine, and the Cl2 is obtained by electrolysis and can be reused. The entire Cl2 reflow process is carried out in the channel and is directly charged into the bromine extraction solution for reaction, which has little pollution to the environment and high operation safety.

[0058] The heating bushing 7 is filled with a resistance wire, and the working temperature of the heating bushing 7 is 60° C. In this embodiment, the heating bushing 7 is provided to heat the bromine extraction waste liquid, so that the bromine generated by electrolysis evaporates, and the mixed gas Br2+Cl2 flows directionally into the bromine collection structure for further treatment.

[0059] The above embodiments are merely preferred implementations of the present invention. Any simple modification, amendment and substitution of the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for secondary extraction of bromine using primary bromine extraction wastewater, characterized in that: The processing steps include: S1 uses graphite electrode as cathode and platinum electrode as anode to construct electrolysis facilities; The electrolysis facility comprises an electrolytic cell A and an electrolytic cell B, wherein the platinum electrode is located in the electrolytic cell A, the graphite electrode is located in the electrolytic cell B, the electrolytic cell A contains a primary bromine extraction waste liquid, and the electrolytic cell B contains a cathode electrolyte; A salt bridge is provided between the electrolytic cell A and the electrolytic cell B; The electrolysis facility also includes: A bromine collection structure, comprising a drainage cover (1) covering an electrolytic cell A, a condenser (3), a conduit (2) for connecting the drainage cover (1) and the condenser (3), a bromine collection bottle (5), and a connecting pipe (4) for connecting the bromine collection bottle (5) and the condenser (3); A Cl2 reflux pipe (6) fixedly installed and penetrating a side wall corresponding to the connecting pipe (4); and a heating sleeve (7) fixedly mounted on the electrolytic cell A; The conduit (2) is fixedly connected to the gas outlet end of the drainage cover (1), the gas inlet end of the condenser (3) is arranged obliquely upward, the bromine collection bottle (5) is located at a position on the corresponding side of the electrolytic cell A, and the lower end of the connecting pipe (4) is inserted into the bromine collection bottle (5); The air inlet end of the Cl2 reflux pipe (6) is located above the bromine collecting bottle (5), and the air outlet end of the Cl2 reflux pipe (6) extends into the primary bromine extraction liquid contained in the electrolytic cell A; The heating sleeve (7) is filled with a resistance wire, and the working temperature of the heating sleeve (7) is 60° C.; S2 starts the electrolysis facility to carry out electrolytic oxidation treatment; While S3 is electrolytically oxidizing, the primary bromine extraction waste liquid is heated; S4 separates the mixed steam generated at the platinum electrode by condensation, collects the liquid formed by condensation, and refills the gas into the primary bromine extraction waste liquid; S5 collects H2 generated at the graphite electrode for reuse as a hydrogen source; S6 Detection of Br in the anolyte by turbidimetry - When the concentration of Br - When the concentration no longer decreases, the electrolysis facility is shut down.

2. The method for secondary extraction of bromine using primary bromine extraction waste liquid according to claim 1, characterized in that: The cathode electrolyte is ethylene carbonate, propylene carbonate, diethyl carbonate or maleic acid.

3. The method for secondary extraction of bromine using primary bromine extraction waste liquid according to claim 2, characterized in that: The preparation method of the salt bridge is specifically performed as follows: agar is placed in a container filled with distilled water, heated in a water bath at 95-100° C. until the agar is completely dissolved, KCl is added while stirring until the mixture is evenly mixed, the mixture is added to a glass curved tube, and the mixture is allowed to stand until it condenses to obtain the salt bridge.

4. The method for secondary extraction of bromine using primary bromine extraction waste liquid according to claim 3, characterized in that: The mass volume ratio of the agar to distilled water is 1:95-98, and the ratio of agar to KCl is 1:9-11.

5. The method for secondary extraction of bromine using primary bromine extraction waste liquid according to claim 1, characterized in that: The working parameters of the electrolysis facility are: voltage 3~6V, current density 0.05~0.1A / cm².

6. The method for secondary extraction of bromine using primary bromine extraction waste liquid according to claim 1, characterized in that: The heating temperature for heating the primary bromine extraction waste liquid is 55-60°C.

7. The method for secondary extraction of bromine using primary bromine extraction waste liquid according to claim 1, characterized in that: Br2 and Cl2 form the mixed steam, and the temperature of the condensation process is 1~10℃.

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