A treatment method for high-salt wastewater of N-acyl sarcosine

Abstract

The present invention relates to the technical field of industrial wastewater treatment, and specifically discloses a method for treating N-acyl sarcosine high-salt wastewater. First, the present invention adopts the method of distillation and concentration to evaporate the low-boiling solvent in the N-acyl sarcosine high-salt wastewater from the system, and then performs solid-liquid separation to recover N-acyl sarcosine; for the high-salt wastewater separation liquid from which N-acyl sarcosine is recovered, barium chloride is added under a specific strong alkaline environment, so that barium chloride fully reacts with MIDA to generate MIDA barium salt, effectively ensuring the removal rate of MIDA, and at the same time obtaining a by-product of high-purity MIDA barium salt; in order to further ensure the water quality of the N-acyl sarcosine high-salt wastewater, a method combining the addition of sodium carbonate and specific resin adsorption is adopted to remove various impurities in the wastewater; and a method of post-treating the wastewater by adding an alcohol solvent is combined to recover the by-product sodium chloride therein, ensuring the maximum recovery rate and purity of the sodium chloride product.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial wastewater treatment, and particularly to a method for treating high-salt wastewater containing N-acyl sarcosine. Background Art

[0002] N-acyl sarcosine and its salts are relatively widely used varieties among amino acid surfactants. They are mostly synthesized from fatty acyl chloride and sodium sarcosinate. In addition to having properties such as emulsification, washing, dispersion, foaming, penetration, and solubilization, more importantly, they have the advantages of low irritation, low toxicity, good biodegradability, and fine and stable foam. Therefore, they have been widely used in many fields. At present, N-acyl sarcosine and its salts are widely used in the formulations of corrosion inhibitors, lubricants, dye additives, foaming agents, fiber cleaning agents, antistatic agents, mineral flotation, shampoos, toothpastes, etc.

[0003] In the process of synthesizing N-acyl sarcosine from fatty acyl chloride and sodium sarcosinate, the resulting high-salt wastewater inevitably contains various organic substances such as fatty acids, N-acyl sarcosine, sodium sarcosinate, N-methyliminodiacetic acid (MIDA), and hydrophilic solvents involved in the reaction process, resulting in high pollution degree, large water volume change, complex water quality composition, and poor biodegradability. At present, enterprises mostly adopt the method of evaporation and concentration for treatment. Due to the various organic substances it contains, the purity of the obtained solid salt is only about 80%. The by-product salt with this purity cannot be used as an industrial product and requires subsequent treatment, and the treatment difficulty is relatively large, which also additionally increases the environmental protection treatment cost of enterprises. Therefore, there is an urgent need for an economically efficient method for treating high-salt wastewater containing N-acyl sarcosine that can effectively recover inorganic salts in the high-salt wastewater containing N-acyl sarcosine and does not cause secondary pollution. Summary of the Invention

[0004] Aiming at the problems of the existing high-salt wastewater containing N-acyl sarcosine having more organic substances, high treatment difficulty, low purity of the by-product salt, and causing secondary pollution to the environment, etc., the present invention provides a method for treating high-salt wastewater containing N-acyl sarcosine. It mainly separates and recovers various effective components in the high-salt wastewater containing N-acyl sarcosine one by one through steps such as distillation, removing MIDA with barium chloride, adsorption by a specific resin, and alcohol precipitation, realizing the resource utilization of production wastewater and having no secondary pollution problem, and having relatively high economic and environmental benefits.

[0005] To solve the above technical problems, the technical solution provided by the present invention is:

[0006] A method for treating high-salt wastewater containing N-acyl sarcosine, comprising the following steps:

[0007] Step a: Distill and concentrate the high-salt wastewater of N-acyl sarcosine, cool the remaining mother liquor after distillation, and perform solid-liquid separation to obtain N-acyl sarcosine and the high-salt wastewater separation liquid.

[0008] Step b: Adjust the pH of the high-salt wastewater separation liquid to strong alkalinity, add barium chloride or its hydrate, carry out a heat-preserving reaction, and perform solid-liquid separation to obtain barium N-methyliminodiacetate and the purified high-salt wastewater.

[0009] Step c: Add sodium carbonate to the purified high-salt wastewater, carry out a heat-preserving reaction, and perform solid-liquid separation to obtain barium carbonate and the refined high-salt liquid.

[0010] Step d: Pass the refined high-salt liquid through macroporous chelating resin for adsorption, distill and dehydrate the adsorbed wastewater, add an alcohol solvent, heat, keep warm, and perform solid-liquid separation to obtain sodium chloride.

[0011] Among them, the macroporous chelating resin is an aminophosphonic acid chelating resin crosslinked by styrene and divinylbenzene.

[0012] Compared with the prior art, the treatment method of N-acyl sarcosine high-salt wastewater provided by the present invention first adopts the method of distillation and concentration to evaporate the low-boiling solvent in the N-acyl sarcosine high-salt wastewater from the system, and the N-acyl sarcosine dissolved in the system gradually precipitates. Through subsequent solid-liquid separation, the N-acyl sarcosine in the high-salt wastewater is recovered; for the high-salt wastewater separation liquid from which N-acyl sarcosine is recovered, barium chloride or its hydrate is added under a specific strong alkaline environment, so that barium chloride fully reacts with MIDA to generate MIDA barium salt, effectively ensuring the removal rate of MIDA, laying a basic condition for further reducing the organic matter concentration in the N-acyl sarcosine high-salt wastewater, and at the same time obtaining a by-product of high-purity MIDA barium salt; in order to further ensure the water quality of the N-acyl sarcosine high-salt wastewater, a method combining the addition of sodium carbonate and specific resin adsorption is adopted to remove various impurities in the wastewater; and a method of post-treating the wastewater by adding an alcohol solvent is combined to recover the by-product sodium chloride therein, ensuring the maximum recovery rate and purity of the sodium chloride product.

[0013] The whole treatment process of the present invention is simple, safe and controllable, and can separate and recover various effective components in the N-acyl sarcosine high-salt wastewater one by one without secondary pollution. It not only reduces the treatment cost of the wastewater, but also obtains by-products of N-acyl sarcosine, MIDA barium salt and sodium chloride with higher added value, realizes the resource utilization of production wastewater, effectively solves the problem of treating N-acyl sarcosine high-salt wastewater, and has high economic and environmental benefits and high practical value.

[0014] It should be noted that the pH of the N-acyl sarcosine high-salt wastewater in the present invention is 1.0 - 2.0.

[0015] Preferably, in step a, when the top temperature of the distillation kettle reaches 90°C to 95°C, the distillation is stopped.

[0016] By controlling the temperature of distillation and concentration, low-boiling organic solvents in the high-salt wastewater of N-acyl sarcosine can be fully removed, ensuring the maximum recovery rate of the low-boiling solvents.

[0017] The preferred distillation temperature and the control of the distillation stop can make the quality of the high-salt wastewater separation liquid reach 90% to 94% of the quality of the initial high-salt wastewater of N-acyl sarcosine, thus avoiding excessive entrainment of the high-salt wastewater separation liquid in the subsequently precipitated N-acyl sarcosine. On the premise of ensuring the complete evaporation of the low-boiling organic solvent, the quality of the recovered N-acyl sarcosine is further ensured.

[0018] Preferably, in step a, the temperature for cooling is 15°C to 20°C.

[0019] As the low-boiling organic solvent is removed during the distillation process, N-acyl sarcosine continuously precipitates from the high-salt wastewater. When the temperature reaches 95°C, the heat source is turned off for cooling. As the temperature decreases, the precipitation amount of N-acyl sarcosine gradually increases.

[0020] By limiting the distillation temperature and the solid-liquid separation temperature, not only can the maximum recovery rate of N-acyl sarcosine be ensured, but also the quality of the recovered N-acyl sarcosine can be guaranteed, thus effectively reducing the production cost of N-acyl sarcosine products.

[0021] Furthermore, in step a, after the recovered low-boiling solvent removed by distillation, it can be recycled as a solvent in the synthesis process of N-acyl sarcosine, reducing the production cost.

[0022] Preferably, in step b, the strong alkalinity refers to a pH of 10.0 to 11.0.

[0023] Under specific pH conditions, it is beneficial for barium chloride to react fully with MIDA.

[0024] Exemplarily, in step b, a sodium hydroxide solution is used to adjust the pH of the high-salt wastewater of N-acyl sarcosine to 10.0 to 11.0.

[0025] Specifically, in step b, a sodium hydroxide solution with a mass concentration of 32% is used to adjust the pH of the high-salt wastewater of N-acyl sarcosine to 10.0 to 11.0.

[0026] Preferably, in step b, the temperature for the heat preservation reaction is 70°C to 90°C, and the time is 0.5 h to 1.0 h.

[0027] Preferably, in step b, the addition amount of barium chloride or its hydrate is 0.035 to 0.040 times the mass of the high-salt wastewater separation liquid.

[0028] Under specific temperature, time, and specific addition amount of barium chloride, it is beneficial to ensure the reaction effect of barium chloride and MIDA, ensure the removal rate of MIDA, and thus effectively reduce the concentration of organic matter in the high-salt wastewater.

[0029] Specifically, as a specific embodiment of the present invention, before adding barium chloride or its hydrate, the temperature of the high-salt wastewater separation liquid is controlled at 70°C to 90°C.

[0030] Preferably, in step c, the addition amount of sodium carbonate is 0.008 to 0.010 times the mass of the high-salt wastewater separation liquid.

[0031] Preferably, in step c, the temperature of the heat preservation reaction is 15°C to 20°C, and the time is 0.5 h to 1.0 h.

[0032] Specifically, as a specific embodiment of the present invention, before adding sodium carbonate, the temperature of the high-salt wastewater purification liquid is controlled at 15°C to 20°C.

[0033] Adding sodium carbonate to the high-salt wastewater purification liquid and limiting the heat preservation temperature and time can enable the excessive barium ions in the high-salt wastewater purification liquid to be completely separated from the system in the form of barium carbonate, which is beneficial to improving the quality of the high-salt wastewater refined liquid.

[0034] Preferably, in step d, the macroporous chelating resin is Seplite LSC-500.

[0035] Preferably, in step d, the adsorption flow rate is 1.0 BV / h to 1.2 BV / h.

[0036] Inevitably, trace amounts of barium ions or other trace organic impurities are entrained in the separated high-salt wastewater refined liquid. Using a specific macroporous chelating resin can fully remove the trace impurities remaining in the high-salt refined wastewater, creating a basic condition for subsequent recovery of high-purity sodium chloride.

[0037] It should be noted that when the adsorption volume of the macroporous chelating resin reaches 40 BV to 45 BV, it is desorbed with dilute hydrochloric acid, and the desorbed macroporous chelating resin can be recycled.

[0038] Preferably, in step d, the distillation dehydration is carried out by negative pressure distillation, the temperature of the distillation dehydration is 80°C to 90°C, and the mass of the wastewater after dehydration is 0.35 to 0.45 times the mass of the high-salt refined liquid.

[0039] The refined liquid of the high-salt wastewater is dehydrated to form a supersaturated system of sodium chloride - water, so that sodium chloride precipitates from the refined liquid of the high-salt wastewater; by limiting the mass ratio of the dehydrated wastewater to the refined liquid of the high-salt wastewater, on the premise of ensuring the material flow state of the supersaturated sodium chloride - water system, the maximum amount of solid sodium chloride can be precipitated from the refined liquid system of the high-salt wastewater.

[0040] Preferably, in step d, the alcohol solvent is ethanol or isopropyl alcohol.

[0041] Preferably, in step d, the addition amount of the alcohol solvent is 1.0 - 2.0 times the mass of the wastewater after distillation dehydration.

[0042] It should be noted that the wastewater after separating the solid sodium chloride needs to be recycled and can be directly applied to the reaction system of N-acyl sarcosine as a reaction solvent.

[0043] By limiting the solvent, the solvent after the wastewater treatment can be recycled and applied to the reaction system of N-acyl sarcosine, avoiding the generation of secondary pollution wastewater and reducing the treatment cost of the high-salt wastewater of N-acyl sarcosine.

[0044] By limiting the addition amount of the alcohol solvent, sodium chloride can be fully precipitated from the wastewater, ensuring the maximum recovery rate of sodium chloride.

[0045] Preferably, in step d, the heating temperature is 75°C - 85°C, and the heat preservation time is 0.5 h - 1.0 h.

[0046] Preferably, in step d, the temperature of the solid-liquid separation is 20°C - 30°C.

[0047] Adding a limited alcohol solvent to the supersaturated sodium chloride - water system and controlling the heating temperature and heat preservation time can enable the organic substances such as sarcosine entrained in the solid sodium chloride to come into full contact with the alcohol solvent and dissolve in the solvent system, improving the quality of the sodium chloride product; by further limiting the separation temperature, on the one hand, the loss of the alcohol solvent can be reduced, and on the other hand, the entrainment of the solid sodium chloride can be further reduced, ensuring the quality of the recovered solid sodium chloride salt.

[0048] The treatment method for high-salt wastewater of N-acyl sarcosine provided by the present invention has simple process operation and low energy consumption. It can recover various effective components in the high-salt wastewater of N-acyl sarcosine one by one, without generating secondary three wastes. The various by-products with relatively high added value obtained by recovery are also beneficial to reducing the treatment cost of the high-salt wastewater of N-acyl sarcosine. At the same time, the purity of the obtained sodium chloride solid salt can reach more than 99%. It not only effectively solves the problem of treating the high-salt wastewater of N-acyl sarcosine, but also realizes the comprehensive treatment and resource utilization of the wastewater, with high economic and environmental benefits and extremely high promotion value. Detailed Embodiments

[0049] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] To better illustrate the present invention, further examples are given below through embodiments.

[0051] In the following examples and comparative examples, the high-salt wastewater of N-acyl sarcosine is the wastewater generated in the N-acyl sarcosine process by reacting fatty acyl chloride and sodium sarcosinate as raw materials. After testing, the pH of the high-salt wastewater of N-acyl sarcosine used in the following examples and comparative examples is 1.85 (25 °C), the COD is 149500 mg / L, the mass concentration of sodium chloride is 22.06%, the mass concentration of sodium sarcosinate is 0.80%, and the mass concentration of MIDA-2Na is 1.78%.

[0052] Example 1

[0053] This example provides a treatment method for high-salt wastewater of N-acyl sarcosine, including the following steps:

[0054] Step 1: Under normal pressure conditions, add 8000 g of high-salt wastewater of N-acyl sarcosine into the distillation kettle, heat it, and stop heating when the temperature at the top of the column reaches 95 °C. Cool the temperature in the distillation kettle to 15 °C, filter it, and obtain 7200 g of high-salt wastewater separation liquid; dry the solid obtained by filtration to obtain 42 g of N-acyl sarcosine product, with an HPLC purity of 95.6%;

[0055] Step 2: Use 266.7 g of 32 wt% NaOH solution to adjust the pH of 7200 g of high-salt wastewater separation liquid to 11.0, then heat it to 90 °C, add 280 g of barium chloride dihydrate, stir and keep warm for 0.5 h, filter it, and obtain 7604 g of high-salt wastewater purification liquid; dry the solid obtained by filtration to obtain 142 g of MIDA barium salt product, with an HPLC purity of 98.73%;

[0056] Step 3: Control the temperature of the high-salt wastewater purification liquid at 15°C. Add 72 g of sodium carbonate to 7604 g of the high-salt wastewater purification liquid, stir while maintaining the temperature for 1.0 h, and then filter to obtain 7582 g of the refined high-salt wastewater liquid. Dry the solid obtained by filtration to obtain 90 g of barium carbonate.

[0057] Step 4: Pass 7582 g of the refined high-salt wastewater liquid through Seplite LSC-500 macroporous chelating resin for adsorption at an adsorption flow rate of 1.1 BV / h to obtain 7575 g of the adsorption liquid. Sample and detect that the barium ion concentration is 0. Distill the adsorption liquid under reduced pressure at 85°C for 1.5 h to obtain 3408 g of the concentrated liquid. Add 6816 g of anhydrous isopropanol to it, heat up to 75°C and reflux for 1.0 h, then cool down to 20°C for filtration and drying to obtain 1890 g of sodium chloride solid. Sample and detect that its moisture content is 0.8%, the sodium chloride content is 99.30%, and the barium ion content is 0.

[0058] Example 2

[0059] This example provides a method for treating N-acyl sarcosine high-salt wastewater, which includes the following steps:

[0060] Step 1: Under atmospheric pressure, add 8000 g of N-acyl sarcosine high-salt wastewater to the distillation kettle, heat it, and stop heating when the temperature at the top of the tower reaches 90°C. Cool down the temperature in the distillation kettle to 20°C and filter to obtain 7520 g of the high-salt wastewater separation liquid. Dry the solid obtained by filtration to obtain 40 g of N-acyl sarcosine product with an HPLC purity of 96.2%.

[0061] Step 2: Use 264.0 g of 32 wt% NaOH solution to adjust the pH of 7520 g of the high-salt wastewater separation liquid to 10.0, then heat it up to 70°C, add 300.8 g of barium chloride dihydrate, stir and keep warm for 1.0 h, and filter to obtain 7941 g of the high-salt wastewater purification liquid. Dry the solid obtained by filtration to obtain 143 g of MIDA barium salt product with an HPLC purity of 98.51%.

[0062] Step 3: Control the temperature of the high-salt wastewater purification liquid at 20°C. Add 60.2 g of sodium carbonate to 7941 g of the high-salt wastewater purification liquid, stir while maintaining the temperature for 0.5 h, and filter to obtain 7904 g of the refined high-salt wastewater liquid. Dry the solid obtained by filtration to obtain 97 g of barium carbonate.

[0063] Step 4: Pass 7904 g of the refined high-salt wastewater into Seplite LSC-500 macroporous chelating resin for adsorption at an adsorption flow rate of 1.2 BV / h to obtain 7900 g of the adsorption solution. Take a sample for testing and the barium ion concentration is 0. Distill the adsorption solution under reduced pressure at 90°C for 1.5 h to obtain 2765 g of the concentrated solution. Add 2765 g of anhydrous isopropanol to it, heat up to 85°C and reflux for 0.5 h, then cool down to 30°C for filtration and drying to obtain 1906 g of sodium chloride solid. Take a sample for testing, the moisture content is 0.6%, the sodium chloride content is 99.42%, and the barium ion content is 0.

[0064] Example 3

[0065] This example provides a method for treating high-salt wastewater of N-acyl sarcosine, which includes the following steps:

[0066] Step 1: Under normal pressure, add 8000 g of N-acyl sarcosine high-salt wastewater into the distillation kettle, heat it, and stop heating when the temperature at the top of the tower reaches 93°C. Cool down the temperature in the distillation kettle to 18°C, filter to obtain 7360 g of the high-salt wastewater separation liquid. Dry the solid obtained by filtration to obtain 41 g of N-acyl sarcosine product, and the HPLC purity is 95.9%;

[0067] Step 2: Use 260.0 g of 32 wt% NaOH solution to adjust the pH of 7360 g of the high-salt wastewater separation liquid to 10.5, then heat up to 80°C, add 272.3 g of barium chloride dihydrate, stir and keep warm for 0.5 h, filter to obtain 7752 g of the high-salt wastewater purification liquid. Dry the solid obtained by filtration to obtain 140 g of MIDA barium salt product, and the HPLC purity is 98.84%;

[0068] Step 3: Control the temperature of the high-salt wastewater purification liquid at 18°C, add 66.2 g of sodium carbonate to 7752 g of the high-salt wastewater purification liquid, keep warm and stir for 0.5 h, filter to obtain 7722 g of the refined high-salt wastewater. Dry the solid obtained by filtration to obtain 93.5 g of barium carbonate;

[0069] Step 4: Pass 7722 g of the refined high-salt wastewater into Seplite LSC-500 macroporous chelating resin for adsorption at an adsorption flow rate of 1.0 BV / h to obtain 7701 g of the adsorption solution. Take a sample for testing and the barium ion concentration is 0. Distill the adsorption solution under reduced pressure at 90°C for 2.0 h to obtain 3088 g of the concentrated solution. Add 4632 g of absolute ethanol to it, heat up to 78°C and reflux for 0.5 h, then cool down to 25°C for filtration and drying to obtain 1893 g of sodium chloride solid. Take a sample for testing, the moisture content is 0.75%, the sodium chloride content is 99.38%, and the barium ion content is 0.

[0070] Comparative Example 1

[0071] This comparative example provides a method for treating high-salt wastewater of N-acyl sarcosine. The steps are the same as those in Example 1, except that the type of macroporous adsorption resin in Step 4 is different. The specific steps are as follows:

[0072] Step 1: Under normal pressure, add 8000 g of high-salt wastewater of N-acyl sarcosine into a distillation kettle, heat it, and stop heating when the temperature at the top of the tower reaches 95 °C. Then cool the temperature in the distillation kettle to 15 °C, filter it to obtain 7200 g of high-salt wastewater separation liquid; dry the solid obtained by filtration to obtain 42 g of N-acyl sarcosine product, and the HPLC purity is 95.6%.

[0073] Step 2: Use 266.7 g of 32 wt% NaOH solution to adjust the pH of 7200 g of high-salt wastewater separation liquid to 11.0, then heat it up to 90 °C, add 280 g of barium chloride dihydrate, stir and keep warm for 0.5 h, filter it to obtain 7604 g of high-salt wastewater purification liquid; dry the solid obtained by filtration to obtain 142 g of MIDA barium salt product, and the HPLC purity is 98.59%.

[0074] Step 3: Control the temperature of the high-salt wastewater purification liquid at 15 °C, add 72 g of sodium carbonate to 7604 g of high-salt wastewater purification liquid, keep warm and stir for 1.0 h, filter it to obtain 7582 g of high-salt wastewater refined liquid; dry the solid obtained by filtration to obtain 90 g of barium carbonate.

[0075] Step 4: Pass 7582 g of high-salt wastewater refined liquid through HYA-105B macroporous adsorption resin for adsorption, and the adsorption flow rate is 1.1 BV / h to obtain 7575 g of adsorption liquid. Take a sample to detect that the barium ion concentration is 7602 ppm; distill the adsorption liquid under reduced pressure at 85 °C for 1.5 h to obtain 3408 g of concentrated liquid. Add 6816 g of anhydrous isopropanol to it, heat it up to 75 °C and reflux for 1.0 h, then cool it to 20 °C for filtration and drying to obtain 1973 g of sodium chloride solid. Take a sample to detect its moisture content of 0.78%, sodium chloride content of 95.10%, and barium ion content of 2.918%.

[0076] Comparative Example 2

[0077] This comparative example provides a method for treating high-salt wastewater of N-acyl sarcosine. The steps are the same as those in Example 1, except that the pH adjustment step in Step 2 is not carried out and the type of macroporous adsorption resin in Step 4 is different. The steps are as follows:

[0078] Step 1: Under atmospheric pressure, add 8000 g of N-acyl sarcosine high-salt wastewater into the distillation kettle, heat it, and stop heating when the temperature at the top of the column reaches 95 °C. Cool the temperature in the distillation kettle to 15 °C, filter it to obtain 7200 g of high-salt wastewater separation liquid; dry the solid obtained by filtration to obtain 42 g of N-acyl sarcosine product, and the HPLC purity is 95.6%;

[0079] Step 2: Heat 7200 g of high-salt wastewater separation liquid to 90 °C, add 280 g of barium chloride dihydrate, stir and keep warm for 0.5 h, filter it to obtain 7463 g of high-salt wastewater purification liquid; dry the solid obtained by filtration to obtain 15 g of MIDA barium salt product, and the HPLC purity is 92.15%;

[0080] Step 3: Control the temperature of the high-salt wastewater purification liquid at 15 °C, add 72 g of sodium carbonate to 7463 g of high-salt wastewater purification liquid, keep warm and stir for 1.0 h, filter it to obtain 7401 g of high-salt wastewater refined liquid; dry the solid obtained by filtration to obtain 134 g of barium carbonate;

[0081] Step 4: Pass 7401 g of high-salt wastewater refined liquid through HYA-105B macroporous adsorption resin for adsorption, and the adsorption flow rate is 1.1 BV / h to obtain 7390 g of adsorption liquid. Take a sample to detect that the barium ion concentration is 8660 ppm; distill the adsorption liquid under reduced pressure at 85 °C for 1.5 h to obtain 3330 g of concentrated liquid. Add 6660 g of anhydrous isopropanol to it, heat it to 75 °C and reflux for 1.0 h, then cool it to 20 °C for filtration and drying to obtain 1941 g of sodium chloride solid. Take a sample to detect that its moisture content is 0.76%, the sodium chloride content is 90.99%, and the barium ion content is 3.297%.

[0082] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for treating high-salt wastewater of N-acyl sarcosine, characterized in that, It includes the following steps: Step a: Distill and concentrate the high-salt wastewater of N-acyl sarcosine, cool the remaining mother liquor after distillation, and perform solid-liquid separation to obtain N-acyl sarcosine and a high-salt wastewater separation liquid; Step b: Adjust the pH of the high-salt wastewater separation liquid to strong alkalinity, add barium chloride or its hydrate, carry out a heat-preserving reaction, and perform solid-liquid separation to obtain barium N-methyliminodiacetate and a purified high-salt wastewater liquid; Step c: Add sodium carbonate to the purified high-salt wastewater liquid, carry out a heat-preserving reaction, and perform solid-liquid separation to obtain barium carbonate and a refined high-salt liquid; Step d: Pass the refined high-salt liquid through a macroporous chelating resin for adsorption, distill and dehydrate the adsorbed wastewater, add an alcohol solvent, heat, keep warm, and perform solid-liquid separation to obtain sodium chloride; Among them, the macroporous chelating resin is an aminophosphonic acid chelating resin crosslinked by styrene and divinylbenzene.

2. The treatment method of N-acyl sarcosine high-salt wastewater according to claim 1, wherein In step a, stop distillation when the top temperature of the distillation kettle reaches 90°C to 95°C.

3. The treatment method of N-acyl sarcosine high-salt wastewater according to claim 1, characterized in that, In step a, the temperature for cooling is 15°C to 20°C.

4. The treatment method of N-acyl sarcosine high-salt wastewater according to claim 1, characterized in that, In step b, the strong alkalinity means a pH of 10.0 to 11.0; and / or In step b, the temperature for the heat-preserving reaction is 70°C to 90°C, and the time is 0.5 h to 1.0 h.

5. The treatment method of high-salt wastewater of N-acyl sarcosine according to claim 1, wherein, In step b, the addition amount of barium chloride or its hydrate is 0.035 to 0.040 times the mass of the high-salt wastewater separation liquid.

6. The treatment method of N-acyl sarcosine high-salt wastewater according to claim 1, characterized in that, In step c, the addition amount of sodium carbonate is 0.008 to 0.010 times the mass of the high-salt wastewater separation liquid.

7. The treatment method of N-acyl sarcosine high-salt wastewater according to claim 1, characterized in that, In step c, the temperature for the heat-preserving reaction is 15°C to 20°C, and the time is 0.5 h to 1.0 h.

8. The treatment method of N-acyl sarcosine high-salt wastewater according to claim 1, characterized in that, In step d, the macroporous chelating resin is Seplite LSC-500; and / or In step d, the flow rate for adsorption is 1.0 BV / h to 1.2 BV / h.

9. The treatment method of N-acyl sarcosine high-salt wastewater according to claim 1, characterized in that, In step d, the distillation and dehydration adopt a negative-pressure distillation method, the temperature for distillation and dehydration is 80°C to 90°C, and the mass of the wastewater after dehydration is 0.35 to 0.45 times the mass of the refined high-salt liquid; and / or In step d, the alcohol solvent is ethanol or isopropanol; and / or In step d, the addition amount of the alcohol solvent is 1.0 to 2.0 times the mass of the wastewater after distillation and dehydration.

10. The treatment method of N-acyl sarcosine high-salt wastewater according to claim 1, characterized in that, In step d, the temperature for heating is 75°C to 85°C, and the time for keeping warm is 0.5 h to 1.0 h; and / or In step d, the temperature for solid-liquid separation is 20°C to 30°C.