Method for reducing TOC index by using regenerated extraction agent

Abstract

The invention discloses a method for reducing TOC (total organic carbon) index by using a regenerated extraction agent, which comprises the following steps: taking concentrated acid, standing and clarifying for 2 days, taking supernatant liquid for experiment after clarifying, taking a system no-load extraction agent and 10% sodium hydroxide according to a volume ratio of 1: 1 for extraction and phase separation when the solid content is less than 0.5% at the moment to obtain a regenerated ester phase; washing the obtained regenerated ester phase with desalted water according to the volume ratio of 1: 1 until the regenerated ester phase is neutral, washing for 4 times for later use, extracting the regenerated ester phase and the concentrated acid to obtain raffinate acid and a loaded ester phase, carrying out reverse extraction on the obtained loaded ester phase to obtain reverse extraction acid and a no-load ester phase, and detecting the obtained reverse extraction acid. The method disclosed by the invention has the beneficial effects that the time for extracting and splitting phases by utilizing the regenerated extracting agent is shortened, TOC in the regenerated reverse extraction acid is only 1 / 4-1 / 5 of that before regeneration, carried organic matters are greatly reduced, indexes of F and Fe are also greatly reduced except TOC, the ester phase extraction capability after regeneration is enhanced, and phosphoric acid extracted in the reverse extraction process is also easily reversely extracted.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a method for reducing TOC index by utilizing a regenerated extractant. Background Art

[0002] Total organic carbon (TOC) is the total amount of organic matter in water expressed as carbon content, and the result is expressed as mass concentration (mg / L) of carbon (C). Carbon is a common component of all organic matter and the main element of organic matter. The higher the TOC value of water, the higher the organic content in the water. Therefore, TOC can be used as an indicator to evaluate organic pollution in water quality.

[0003] The TOC index in the stripping acid on the production unit is generally around 600ppm, while the TOC index of the stripping acid obtained by laboratory experiments using fresh extractants and regenerated extractants is generally around 200ppm; at the same time, the TOC index in several acids of the production unit is tracked to confirm that the source of TOC in the stripping acid is mainly from the extraction process, and tributyl phosphate is the main source. There is a certain difference between the TOC index in the stripping acid on the production unit and the TOC index of the stripping acid obtained in the laboratory experiment, so a method of reducing the TOC index using a regenerated extractant is proposed. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for reducing TOC index by using a regenerated extractant.

[0005] The technical scheme is as follows: A method for reducing TOC index by using a regenerated extractant, the main points of which are as follows:

[0006] Step 1: Take the concentrated acid and let it stand for clarification. After clarification, take the upper clear liquid for the experiment;

[0007] Step 2: Take the system empty extractant and sodium hydroxide in a volume ratio of 1:1 for regeneration, extract and separate to obtain a regenerated ester phase;

[0008] Step 3: extracting the regenerated ester phase obtained in step 2 with the concentrated acid obtained in step 1 to obtain raffinate acid and a loaded ester phase;

[0009] Step 4: taking the loaded ester phase obtained in step 3 and stripping it with deionized water to obtain stripping acid and an empty ester phase;

[0010] Step 5: Result detection.

[0011] Preferably, the concentrated acid in step 1 is allowed to stand for 2 days for clarification, and the solid content of the clarified supernatant is less than 0.5%.

[0012] Preferably: the volume of the unloaded extractant in step 2 is 1000 mL, and the volume of sodium hydroxide is 1000 mL.

[0013] Preferably: the sodium hydroxide is a 10% sodium hydroxide solution.

[0014] Preferably, the regeneration in step 2 refers to stirring the reaction in a 60° C. water bath for 30 minutes, then taking out the separated regenerated ester phase and water phase.

[0015] Preferably, the regenerated extractant obtained in step 2 is washed with desalted water at a volume ratio of 1:1 until it becomes neutral, and washed 4 times for standby use.

[0016] Preferably, the extraction in step 3 is to take 800 mL of the regenerated ester phase and 200 mL of the concentrated acid, stir and extract at 60°C for 30 minutes, then stand for 30 minutes to separate the phases, and separate the phases after the ester phase is completely clear to obtain the raffinate acid and the loaded ester phase.

[0017] Preferably, the stripping in step 4 is performed by adding 810 g of deionized water to 810 g of the loaded ester phase, stirring and extracting at 60° C. for 30 min, and then standing for 30 min for phase separation, and separating the phases after the ester phase is completely clear to obtain stripping acid and an empty ester phase.

[0018] Preferably, the time for the ester phase to be completely clear during the extraction process is 2 hours, and the time for the ester phase to be completely clear during the stripping process is 1 hour.

[0019] Preferably: the result detection of step 5 is to detect the obtained stripping acid, and the detection includes phosphorus, sulfur, iron, fluorine and TOC indicators.

[0020] Compared with the prior art, the present invention has the following beneficial effects: the time for extracting and separating phases using the regenerated extractant is shortened, and the TOC in the stripping acid after regeneration is indeed only between 1 / 4 and 1 / 5 of that before regeneration, the organic matter carried is greatly reduced, and in addition to TOC, the indicators of F and Fe are also greatly reduced, the extraction capacity of the ester phase after regeneration is enhanced, and the phosphoric acid extracted during the stripping process is also easily stripped out. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the process of the present invention; DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with embodiments and drawings.

[0023] like Figure 1 As shown, a method for reducing TOC index by using a regenerated extractant comprises the following steps:

[0024] Step 1: Take concentrated acid, let it stand for 2 days to clarify, take the clarified supernatant for the experiment, and the solid content at this time is less than 0.5%;

[0025] Step 2: Regeneration of the extractant: 1000 mL of the system empty extractant and 1000 mL of 10% sodium hydroxide were taken in a volume ratio of 1:1, stirred in a water bath at 60°C for 30 min, and then the phases were taken out and separated. The regenerated ester phase was washed with deionized water in a volume ratio of 1:1 until neutral, and 870 mL (767.57 g) of the regenerated ester was obtained;

[0026] Step 3: Extract the concentrated acid treated in step 1 with the regenerated ester phase obtained in step 2, take 800 mL (about 708.81 g) of the regenerated ester phase and 200 mL (about 337.99 g) of the concentrated acid, stir and extract at 60°C for 30 min, then stand for 30 min to separate the phases, and separate the phases after the ester phase is completely clear for 2 hours to obtain the raffinate acid and the loaded ester phase;

[0027] Step 4: No washing, fine desulfurization and other processes were performed in the experiment. The loaded ester phase was directly stripped with deionized water. About 810 g of the loaded ester phase was taken, 810 g of deionized water was added, and the stripping was stirred at 60°C for 30 min, and then the phases were allowed to stand for 30 min. Then the phases were taken out and placed in a separating funnel until the ester phase was completely transparent (about 1 h) and then the phases were separated to obtain stripped acid and an empty ester phase;

[0028] Step 5: The stripping acid obtained in step 4 is used to measure phosphorus, sulfur, iron, fluorine and TOC indicators.

[0029] To obtain the regenerated extractant, 337.99 g (200 ml) of concentrated acid and 708.81 g (800 ml) of regenerated ester phase were taken in the extraction process. After extraction, 228.03 g of raffinate acid and 811.04 g of loaded ester phase were obtained. In the stripping process, 811.04 g of loaded ester phase obtained in the extraction process was taken, 810.06 g of deionized water was added thereto, and stripping was performed to obtain 865.99 g of stripping acid.

[0030] The stripping acid was tested and the P2O5 content was 7.85%, the Fe content was 0.0358%, and the SO4 2- The content is 0.5818%, the F content is 0.0283%, the TOC content is 0.0163%, and the stripping rate is 44.06%.

[0031] Comparative test example

[0032] In order to ensure that the extractant is regenerated thoroughly and that the regenerated extractant is more capable of reducing TOC indicators, a comparative experiment will be conducted.

[0033] Experiment 1: Regeneration of the extractant

[0034] Take 905.73g (about 1000ml) of the system empty extractant, add 1097.64g of 10% sodium hydroxide (about 1000ml), stir and react in a water bath at 60°C for 30min, then take out the phase separation, and obtain about 960g of ester phase and about 950g of water phase. The color of the water phase is brown, and wash with deionized water until neutral, and obtain about 790g of ester phase, which is the first regeneration. To ensure that the ester phase is regenerated thoroughly, add 500g of 5% sodium hydroxide to the 790g of ester phase obtained after the first regeneration, stir and react in a water bath at 60°C for 30min, then take out the phase separation, and obtain the water phase color transparent, indicating that the regeneration has been complete. The color of the ester phase is basically unchanged from that after the first regeneration, and the mass of the ester phase is 780g, indicating that one regeneration is indeed sufficient under this reaction condition;

[0035] The system was unloaded and the extractant was regenerated with 10% sodium hydroxide at a ratio of 1:1. After phase separation, no third phase appeared. The phase separation was basically complete in 5 minutes, which was much slower than the extraction phase separation. The mass loss of the extractant was about 20%. There was basically no mass loss after the second regeneration.

[0036] Therefore, the extractant only needs to be regenerated once. At the same time, in order to ensure that the indicators are not affected by sodium hydroxide, the regenerated extractant is washed with desalted water at a ratio of 1:1 until it is neutral. During the experiment, it is washed 4 times and then used for extraction.

[0037] Experiment 2: Comparison of empty extractant and regenerated extractant

[0038] Take 708.89 g (800 ml) of the empty organic phase, add 338.01 g (200 ml) of concentrated acid, stir and extract at 60°C for 30 min, then stand for 30 min to separate the phases. After the ester phase is completely clear (about 2 h), separate the phases to obtain the raffinate acid and the loaded ester phase.

[0039] 708.80 g (800 ml) of the regenerated ester phase was added with 337.99 g (200 ml) of concentrated acid. The mixture was extracted with stirring at 60°C for 30 min and then allowed to stand for 30 min for phase separation. After the ester phase was completely clear (about 2 h), the phases were separated to obtain the raffinate acid and the loaded ester phase.

[0040] The loaded ester phase obtained by extracting the empty organic phase and the regenerated ester phase is then stripped with deionized water to obtain stripping acid and an empty ester phase.

[0041] The experimental data of extraction and stripping of the empty organic phase or the regenerated ester phase are recorded as shown in Table 1 below:

[0042] Table 1 Extraction and back extraction data table

[0043]

[0044]

[0045] The raffinate acid obtained in the extraction process of the regenerated extractant is less than that obtained by the empty extractant, while the loaded ester is more. However, more stripping acid is obtained in the stripping process, and less empty ester is obtained. The various indicators of the stripping acid obtained by stripping with the empty extractant and the regenerated extractant are tested, and the result data are recorded as shown in Table 2 below:

[0046] Table 2 Comparison of extraction indexes before and after regeneration of extractant

[0047] Sample name P2O5% Fe% SO4% F％ TOC% Original acid 45.65 / / / 0.0670 No-load extractant raffinate 38.24 / / / / Extraction rate 40.37% Regeneration of extractant raffinate 38.52 / / / / Extraction rate 43.07% No-load extractant stripping acid 6.80 0.0686 1.2698 0.0314 0.0770 Stripping rate 39.94% Regeneration of extractant stripping acid 7.85 0.0358 1.5831 0.0283 0.0163 Stripping rate 44.06%

[0048] According to the above data table, the P2O5 content in the stripping acid after regeneration is 7.85%, the Fe content is 0.0358%, and the SO4 2- The content is 1.5831%, the F content is 0.0283%, the TOC content is 0.0163%, and the stripping rate is 44.06%. Compared with the stripping rate of the stripping acid obtained by the empty extractant, the TOC in the stripping acid after regeneration is indeed only between 1 / 4 and 1 / 5 of that before regeneration. The organic matter carried is greatly reduced. In addition to TOC, the indicators of F and Fe are also greatly reduced. The ester phase extraction capacity is enhanced after regeneration, and the phosphoric acid extracted during the stripping process is also easily stripped out. Therefore, the regenerated extractant can effectively reduce the TOC index, etc.

[0049] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, ordinary technicians in this field can make various similar expressions without violating the purpose and claims of the present invention, and such changes all fall within the scope of protection of the present invention.

Claims

1. A method for reducing TOC index by using a regenerated extractant, characterized in that: The following steps are involved: Step 1: Take the concentrated acid and let it stand for clarification. After clarification, take the upper clear liquid for the experiment; Step 2: Take the system empty extractant and sodium hydroxide in a volume ratio of 1:1 for regeneration, extract and separate to obtain a regenerated ester phase; Step 3: extracting the regenerated ester phase obtained in step 2 with the concentrated acid obtained in step 1 to obtain raffinate acid and a loaded ester phase; Step 4: taking the loaded ester phase obtained in step 3 and stripping it with deionized water to obtain stripping acid and an empty ester phase; Step 5: Result detection.

2. The method of reducing TOC index by using a regenerated extractant according to claim 1, characterized in that: The concentrated acid in step 1 is allowed to stand for 2 days for clarification, and the solid content of the clarified supernatant is less than 0.5%.

3. The method of reducing TOC index by using a regenerated extractant according to claim 1, characterized in that: The volume of the unloaded extractant in the step 2 is 1000 mL, and the volume of the sodium hydroxide is 1000 mL.

4. A method for reducing TOC index by using a regenerated extractant according to claim 1 or 3, characterized in that: The sodium hydroxide is a sodium hydroxide solution with a content of 10%.

5. A method for reducing TOC index by using a regenerated extractant according to claim 1, 3 or 4, characterized in that: The regeneration in step 2 refers to stirring the reaction in a water bath at 60° C. for 30 minutes, then taking out the separated regenerated ester phase and water phase.

6. The method of reducing TOC index by using a regenerated extractant according to claim 1, characterized in that: The regenerated extractant obtained in step 2 is washed with deionized water at a volume ratio of 1:1 until it becomes neutral, and washed 4 times for later use.

7. The method of reducing TOC index by using a regenerated extractant according to claim 1, characterized in that: The extraction in step three is to take 800 mL of the regenerated ester phase and 200 mL of concentrated acid, stir and extract at 60° C. for 30 minutes, then stand for 30 minutes to separate the phases, and separate the phases after the ester phase is completely clear to obtain the raffinate acid and the loaded ester phase.

8. The method of reducing TOC index by using a regenerated extractant according to claim 1, characterized in that: The stripping in step 4 is to add 810 g of deionized water to 810 g of the loaded ester phase, stir and extract at 60° C. for 30 min, then stand for 30 min for phase separation, and separate the phases after the ester phase is completely clear to obtain stripping acid and an empty ester phase.

9. A method for reducing TOC index by using a regenerated extractant according to claim 7 or 8, characterized in that: The time required for the ester phase to be completely clear during the extraction process is 2 hours, and the time required for the ester phase to be completely clear during the stripping process is 1 hour.

10. The method of reducing TOC index by using a regenerated extractant according to claim 1, characterized in that: The result detection of step 5 is to detect the obtained stripping acid, including the detection of phosphorus, sulfur, iron, fluorine and TOC indicators.

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