阅读说明：本技术 安赛蜜废液的处理方法 (Treatment method of acesulfame potassium waste liquid ) 是由 周睿 丁震 陈永旭 郑仁峰 杨峰宝 于 2021-05-28 设计创作，主要内容包括：本申请提供了安赛蜜废液的处理方法,安赛蜜废液为采用双乙烯酮-三氧化硫法制备安赛蜜产生的废液,该方法包括：水分蒸发步骤：在第一预设温度,对安赛蜜废液进行蒸发至水含量达到预设水含量,得到第一物料；中和反应步骤：向第一物料中加入液氨,在密闭反应器中进行中和反应,得到第二物料；和产物分离步骤：将第二物料分离为有机相和水相；对水相进行固液分离,得到硫酸铵粗产品和余液；将有机相作为三乙胺粗产品回收。本申请极大程度上简化了安赛蜜废液处理工艺,缩短了处理时间,显著提高了胺的回收效率。(The application provides a method for treating acesulfame-K waste liquid, wherein the acesulfame-K waste liquid is generated by preparing acesulfame-K by adopting a ketene dimer-sulfur trioxide method, and the method comprises the following steps: water evaporation step: evaporating the acesulfame potassium waste liquid at a first preset temperature until the water content reaches a preset water content to obtain a first material; a neutralization reaction step: adding liquid ammonia into the first material, and performing neutralization reaction in a closed reactor to obtain a second material; and a product separation step: separating the second material into an organic phase and an aqueous phase; carrying out solid-liquid separation on the water phase to obtain an ammonium sulfate crude product and a residual liquid; the organic phase was recovered as a crude triethylamine product. The method greatly simplifies the acesulfame potassium waste liquid treatment process, shortens the treatment time, and obviously improves the recovery efficiency of amine.)

1. A treatment method of acesulfame-K waste liquid, which is waste liquid generated by preparing acesulfame-K by a ketene dimer-sulfur trioxide method, is characterized by comprising the following steps:

water evaporation step: evaporating the acesulfame potassium waste liquid at a first preset temperature until the water content reaches a preset water content to obtain a first material;

a neutralization reaction step: adding liquid ammonia into the first material, and performing neutralization reaction in a closed reactor to obtain a second material; and

and (3) product separation: separating the second material into an organic phase and an aqueous phase; carrying out solid-liquid separation on the water phase to obtain an ammonium sulfate crude product and a residual liquid; the organic phase was recovered as a crude triethylamine product.

2. The method of claim 1, further comprising:

and (3) solvent distillation: distilling the acesulfame potassium waste liquid at a second preset temperature to remove the solvent in the acesulfame potassium waste liquid; and the first preset temperature is less than the second preset temperature.

3. The method according to claim 1, wherein the acesulfame potassium waste solution comprises, based on the total mass of the acesulfame potassium waste solution: 10-30 wt% of sulfuric acid, 5-20 wt% of triethylamine sulfate and 3-5 wt% of impurity organic matters.

4. The method according to claim 3, wherein the molar ratio of the liquid ammonia to the sulfate radicals in the acesulfame-K waste liquor is 2.5-4: 1.

5. The method of claim 4, wherein the neutralization step further comprises: after the neutralization reaction is finished, the obtained third material is distilled to remove the excessive ammonia gas.

6. The method according to claim 1, wherein in the moisture evaporation step, the preset water content is 5-20 wt.%, preferably 8-15 wt.%, more preferably 10 wt.%, based on the total mass of the acesulfame potassium waste liquor.

7. The method as claimed in claim 1, wherein in the neutralization reaction step, the reaction temperature of the neutralization reaction is 100-120 ℃; the reaction time is 2-10 min.

8. The method of claim 1, wherein in the product separation step, the subjecting the aqueous phase to solid-liquid separation to obtain a crude ammonium sulfate product and a residual liquid comprises:

adjusting the pH value of the water phase to 6-8 by using sulfuric acid;

adding an oxidant into the water phase with the pH value adjusted to carry out oxidation reaction; and

and (4) evaporating and crystallizing the water phase after the oxidation reaction is finished to obtain a crude product of ammonium sulfate.

9. The process according to claim 1, wherein in the product separation step, the recovering of the organic phase as a crude triethylamine product comprises:

and cooling the organic phase to 80-85 ℃ in a closed reactor, then carrying out atmospheric distillation, and recovering the distilled residual liquid as a triethylamine crude product.

10. The method of claim 1, further comprising:

a residual liquid recovery step: mixing the residual liquid generated in the product separation step into the acesulfame-K waste liquid.

Technical Field

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a treatment method of acesulfame potassium waste liquid.

Background

Acesulfame potassium (acesulfame potassium) is also called AK sugar, it is a kind of sugar substitute food additive used extensively, the appearance is white crystalline powder, it is an organic synthetic salt, its taste is similar to sugarcane, easy to dissolve in water, slightly soluble in alcohol, its chemical property is stable, it is difficult to appear decomposing and losing efficacy; does not participate in the metabolism of the organism and does not provide energy; the sweetness is higher, and the price is low; no cariogenic property; has good stability to heat and acid.

At present, a diketene-sulfur trioxide method is generally adopted in the synthesis of acesulfame potassium, and the specific reaction steps comprise: reacting sulfamic acid with an amine to form an amine sulfamate salt, and then reacting the amine sulfamate salt with diketene to form an acetoacetamide salt; in the presence of sulfur trioxide, performing cyclization reaction on the acetyl acetamide salt to form a cyclic sulfur trioxide adduct; hydrolyzing the cyclic compound to obtain a hydrolysate; the hydrolysate was subsequently treated with potassium hydroxide to obtain acesulfame potassium (ASK).

In the production process, when the sulfamic acid and the diketene are subjected to the addition reaction, amine, particularly triethylamine is used as a reaction catalyst, after a final product ASK is obtained, the residual wastewater mainly contains amine sulfate, sulfuric acid and impurity organic matters including a small amount of triethylamine, a solvent, byproducts and the like, and the part of wastewater can be discharged after being treated; but on the one hand, the method generates a large amount of treatment cost, and on the other hand, the amine in the wastewater has higher economic value and is discharged to cause waste of resources.

In the prior art, there are treatment methods for generating ammonium sulfate and recovering amine by reacting ammonia (ammonia gas, liquid ammonia, etc.) with sulfate of amine and sulfuric acid, such as chinese patent CN103097297A, chinese patent CN111630039A and chinese patent CN112142602A, etc., but these methods all have the problems of complicated reaction process, long process and low recovery efficiency.

Disclosure of Invention

In view of the above problems, the present application has been made to provide a method for treating acesulfame potassium waste liquid that overcomes or at least partially solves the above problems.

According to one aspect of the application, a method for treating acesulfame potassium waste liquid is provided, wherein the acesulfame potassium waste liquid is produced by preparing acesulfame potassium by adopting a diketene-sulfur trioxide method, and the method comprises the following steps:

water evaporation step: evaporating the acesulfame potassium waste liquid at a first preset temperature until the water content reaches a preset water content to obtain a first material;

a neutralization reaction step: adding liquid ammonia into the first material, and performing neutralization reaction in a closed reactor to obtain a second material; and

and (3) product separation: separating the second material into an organic phase and an aqueous phase; carrying out solid-liquid separation on the water phase to obtain an ammonium sulfate crude product and a residual liquid; the organic phase was recovered as a crude triethylamine product.

Optionally, the method further includes:

and (3) solvent distillation: distilling the acesulfame potassium waste liquid at a second preset temperature to remove the solvent in the acesulfame potassium waste liquid; and the first preset temperature is lower than the second preset temperature.

Optionally, in the above method, the waste acesulfame potassium solution includes, based on the total mass of the waste acesulfame potassium solution: 10-30 wt% of sulfuric acid, 5-20 wt% of triethylamine sulfate and 3-5 wt% of impurity organic matters.

Optionally, in the method, the molar ratio of the liquid ammonia to the sulfate radicals in the acesulfame-K waste liquid is 2.5-4: 1.

Optionally, in the above method, the step of neutralization further comprises: after the neutralization reaction is finished, the obtained third material is distilled to remove the excessive ammonia gas.

Alternatively, in the above method, in the water evaporation step, the water content is preset to be 5 to 20 wt%, preferably 8 to 15 wt%, more preferably 10 wt%, based on the total mass of the acesulfame potassium waste liquid.

Optionally, in the above method, in the neutralization reaction step, the reaction temperature of the neutralization reaction is 100-; the reaction time is 2-10 min.

Optionally, in the above method, in the product separation step, performing solid-liquid separation on the aqueous phase to obtain a crude ammonium sulfate product and a residual liquid includes:

adjusting the pH value of the water phase to 6-8 by using sulfuric acid;

adding an oxidant into the water phase with the pH value adjusted to carry out oxidation reaction; and

and (4) evaporating and crystallizing the water phase after the oxidation reaction is finished to obtain a crude product of ammonium sulfate.

Optionally, in the above method, in the product separation step, the recovering the organic phase as a crude triethylamine product includes:

cooling the organic phase to 80-85 ℃ in a closed reactor, then carrying out atmospheric distillation, and recovering the distilled residual liquid as a triethylamine crude product.

Optionally, the method further includes:

a residual liquid recovery step: the raffinate produced in the product separation step was mixed into acesulfame-K waste.

The beneficial effect of this application lies in: the method comprises the steps of firstly, controlling the water content in the acesulfame-K waste liquid by heating, and then reacting liquid ammonia with amine sulfate and sulfuric acid in the waste liquid in a closed environment, wherein the reaction is rapidly completed due to the simultaneous existence of gas-phase and liquid-phase reactions; greatly simplifies the processing technology of the acesulfame potassium waste liquid, shortens the processing time and obviously improves the recovery efficiency of amine.

The foregoing description is only an overview of the technical solutions of the present application, and the present application can be implemented according to the content of the description in order to make the technical means of the present application more clearly understood, and the following detailed description of the present application is given in order to make the above and other objects, features, and advantages of the present application more clearly understandable.

Detailed Description

The following will describe in greater detail exemplary embodiments of the application with the understanding that the present application may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The idea of the application lies in that aiming at the problems of complex treatment process, long consumed time and low amine recovery efficiency of the acesulfame potassium waste liquid in the prior art, the method for treating the acesulfame potassium waste liquid is provided, on one hand, the content of water in the acesulfame potassium waste liquid is controlled, on the other hand, the neutralization reaction is carried out in a closed container, the reaction time is obviously shortened, the treatment process complexity is reduced, and the amine recovery efficiency is improved.

The flow schematic diagram of the processing method of acesulfame potassium waste liquid provided by the application at least comprises the following steps of S110-S130:

moisture evaporation step S110: and at a first preset temperature, evaporating the acesulfame potassium waste liquid until the water content reaches the preset water content to obtain a first material.

The acesulfame-K waste liquid in the application is a waste liquid generated by preparing acesulfame-K by a ketene dimer-sulfur trioxide method, and triethylamine is taken as a catalyst, so that sulfate, sulfuric acid, impurity organic matters (such as triethylamine, a solvent and byproducts), water and the like of triethylamine exist in the acesulfame-K waste liquid.

In the process of preparing the acesulfame potassium, triethylamine is used as a catalyst, the amount of the triethylamine is not consumed in the whole preparation process, the triethylamine is almost completely converted into triethylamine sulfate at the end of the reaction, and a small amount of the triethylamine is left in impurity organic matters.

In order to ensure that subsequent liquid ammonia can react with triethylamine sulfate and sulfuric acid in the waste liquid quickly, at first, the water in the acesulfame-k waste liquid is evaporated, and specifically, the acesulfame-k waste liquid can be evaporated at a first preset temperature until the water content reaches a preset water content.

The evaporation process can refer to any one of the prior arts, such as atmospheric distillation, vacuum distillation, etc.

The application is not limited to the temperature at which the water evaporates, and in some embodiments of the application, the acesulfame potassium waste liquid may be evaporated in a boiling state in order to evaporate the water as soon as possible.

And finishing the water evaporation step under the condition that the water content reaches the preset water content. In the present application, the presence of a large amount of water reduces the probability of binding between ions, and thus evaporating water can significantly increase the reaction rate; on the other hand, in the present application, both liquid ammonia and triethylamine sulfate need to be dissolved in water, and therefore, the reaction needs water as a "carrier" for the neutralization reaction, and therefore water is necessarily present, water cannot be completely evaporated, and the water content is not as low as possible. Accordingly, the inventors have found through a great deal of experimental studies that the reaction rate is better promoted when the water content reaches a certain predetermined water content, which is 5 to 20 wt% in some embodiments of the present application, 8 to 15 wt% in other embodiments of the present application, and 10 wt% in yet other embodiments of the present application, based on the total mass of the acesulfame potassium waste solution. After the concentration of water is reduced, liquid ammonia is added into a closed container to react, and the reaction is rapidly carried out in the direction of generating ammonium sulfate.

Neutralization reaction step S120: and adding liquid ammonia into the first material, and performing neutralization reaction in a closed reactor to obtain a second material.

This application adopts liquid ammonia to carry out the neutralization to the acesulfame-K waste liquid in airtight reactor, exists sulfate, sulphuric acid, impurity organic matter and water etc. of triethylamine in first material. The liquid ammonia reacts with sulfate of triethylamine to generate triethylamine and ammonium sulfate, and reacts with sulfuric acid to generate ammonium sulfate, so that after the neutralization reaction is finished, an organic phase and an inorganic phase exist in the second material, the organic phase mainly comprises a solvent and triethylamine, and the inorganic phase mainly comprises ammonium sulfate, water and triethylamine which is rarely dissolved in the water.

Different from the prior art, the method adopts the closed container to carry out reaction, and during the reaction, the reaction of gas phase and liquid phase exists simultaneously, so that the reaction rate is improved, the amine conversion rate is high, and the reaction is carried out more thoroughly.

And a product separation step S130: separating the second material into an organic phase and an aqueous phase; carrying out solid-liquid separation on the water phase to obtain an ammonium sulfate crude product and a residual liquid; the organic phase was recovered as a crude triethylamine product.

And finally, separating the product, namely separating the second material into an organic phase and a water phase, wherein the separation process can adopt any one of the prior art, such as standing separation and the like.

The organic phase mainly comprises triethylamine and a solvent, and the solvent can be evaporated to obtain the triethylamine with higher purity. In some embodiments of the present application, to further increase the reaction rate, a solvent distillation step may be performed prior to the moisture evaporation step: distilling the acesulfame potassium waste liquid at a second preset temperature to remove the solvent in the acesulfame potassium waste liquid; and the first preset temperature is lower than the second preset temperature.

Namely, the solvent is removed before the water is evaporated, so that the reaction rate is improved, and the organic phase obtained after the waste liquid treatment is finished does not contain the solvent, so that the trouble of post-treatment is reduced.

Since the boiling point of the solvent is generally lower than that of water, the second preset temperature may be lower than the first preset temperature, and in particular, the second preset temperature may be set according to the kind of the solvent.

The aqueous phase product mainly comprises ammonium sulfate and residual liquid, a small amount of triethylamine dissolved in the residual liquid exists in the residual liquid, and the ammonium sulfate is solid, so that the aqueous phase is subjected to solid-liquid separation to obtain an ammonium sulfate crude product and the residual liquid.

In some embodiments of the present application, the raffinate produced in the product separation step may be mixed into the acesulfame-k waste liquid for recycling treatment, so as to further improve the recovery rate of triethylamine. In the treatment method, other reagents or reactants are introduced in the reaction, and ions in the waste liquid can be basically and completely recovered, so that the generated residual liquid can be recycled.

As can be seen from the method shown in figure 1, the content of water in the acesulfame-K waste liquid is controlled by heating, then the liquid ammonia is reacted with the amine sulfate and the sulfuric acid in the waste liquid in a closed environment, the reaction is quickly completed due to the existence of gas-liquid phase reaction, compared with other methods for recovering amine by using ammonia, the triethylamine sulfate conversion rate is high, the reaction is more thorough, and the amine crude product, the ammonium sulfate crude product and the aqueous phase containing complex components obtained after the reaction are convenient to subsequently treat; greatly simplifies the processing technology of the acesulfame potassium waste liquid, shortens the processing time and obviously improves the recovery efficiency of amine.

Acesulfame potassium waste liquid source and content of each species therein

The acesulfame potassium waste liquid is produced by adopting a diketene-sulfur trioxide method in the prior art to prepare the acesulfame potassium in factories. Usually, the acesulfame-K waste liquid comprises, by weight, 10-30% of sulfuric acid, 5-20% of triethylamine sulfate and 3-5% of impurity organic matters, and the balance is water, based on the total mass of the acesulfame-K waste liquid.

The amount of liquid ammonia

The liquid ammonia is reacted with the sulfate radicals of the acesulfame potassium waste liquid, and the liquid ammonia is usually excessive in order to completely convert the sulfate radicals, and in some embodiments of the application, the molar ratio of the liquid ammonia to the sulfate radicals in the acesulfame potassium waste liquid is 2.5-4: 1. Thus, complete conversion of sulfate radicals is guaranteed, liquid ammonia is converted into ammonia after the neutralization reaction is finished, excessive unreacted ammonia can exist in a reaction system, the excessive ammonia can be distilled, and specifically, after the neutralization reaction is finished, the obtained third material is distilled to remove the excessive ammonia.

Neutralization reaction conditions

In the present application, the neutralization reaction conditions are not limited, and in some embodiments, the reaction temperature of the neutralization reaction in the neutralization reaction step is 100-120 ℃ in the above-described method; the reaction time is 2-10 min.

The reaction temperature is 100-120 ℃, the whole reaction system is in a boiling state, the boiling state is favorable for the rapid reaction, and the recovery rate of triethylamine is improved. In this state, the reaction does not take a long time and can be carried out completely within 2 to 10 min.

In some embodiments of the present application, the treatment of the aqueous phase in the product separation step may be performed by adjusting the pH of the aqueous phase to 6-8 with sulfuric acid; adding an oxidant into the water phase with the pH value adjusted to perform an oxidation reaction so as to reduce the content of ammonia nitrogen in the water phase; and evaporating and crystallizing the water phase after the oxidation reaction is finished to obtain a crude product of ammonium sulfate.

A small amount of liquid ammonia and a small amount of dissolved impurity organic matters including triethylamine and the like exist in the water phase, and firstly, the pH value of the water phase is adjusted to 6-8 by adopting sulfuric acid, namely, the liquid ammonia is neutralized. Then adding an oxidant such as hydrogen peroxide and the like into the ammonia nitrogen reducing agent, thereby reducing the ammonia nitrogen content.

In some embodiments of the present application, in the above process, recovering the organic phase as a crude triethylamine product in the product separation step comprises: and cooling the organic phase to a third preset temperature in a closed reactor, then carrying out atmospheric distillation, and recovering the distilled residual liquid as a triethylamine crude product.

A small amount of solvent can be mixed in triethylamine, in order to improve the purity of the triethylamine, the organic phase can be cooled to 80-85 ℃ in a closed reactor and then is distilled under normal pressure, and the distilled residual liquid is recovered as a crude triethylamine product.

Obtaining waste liquid: the method comprises the steps of preparing acesulfame by adopting a diketene-sulfur trioxide method, separating a water phase and an organic phase after a salt forming step, wherein the water phase is waste liquid required to be treated in the application, in the waste liquid, the mass fraction of sulfuric acid is 10-30%, the mass fraction of triethylamine sulfate is 5-20%, the mass fraction of impurity organic matter components is 3-5%, and the balance is water, wherein triethylamine: the sulfate radical molar ratio is 2: 4-1. In each of the following examples or comparative examples, unless otherwise specified, used acesulfame potassium waste liquid was obtained by the method, and if specifically specified, obtained according to the specification.

It should be noted that, the determination methods of triethylamine and sulfate radical content in the acesulfame potassium waste liquid can refer to the prior art or national standards, such as GB/T23964 and GB/T23835.7, the application is not limited, and details are not repeated in the following examples and comparative examples.

Example 1 (including example 1A, example 1B, example 1C, example 1D, example 1E)

Water evaporation step: the residual liquid generated in the comparative example 1B was equally divided into five equal parts, and parallel experiments were performed, specifically, the residual liquid was heated in a reactor until the water content in the residual liquid reached the predetermined water content, and in examples 1A, 1B, 1C, 1D, and 1E, the water content was specifically shown in table 1, and the first material was obtained.

A neutralization reaction step: adding excessive liquid ammonia into the reaction kettle, sealing the reaction kettle, and maintaining the reaction kettle for a period of time under the condition of a preset reaction temperature, wherein in the examples 1A, 1B, 1C, 1D and 1E, referring to the table 1, specific reaction time and molar ratio of liquid ammonia to sulfate radical, the second material is obtained.

And (3) product separation: after the neutralization reaction is finished, cooling to normal temperature, distilling the second material under normal pressure, and distilling out excessive ammonia gas and the solvent remained in the second material; then separating the second material into an organic phase and an aqueous phase; wherein, the organic phase is recovered as a triethylamine crude product; and filtering the water phase to separate solid from liquid to obtain a crude product of ammonium sulfate and a residual liquid.

Example 2 (including example 2A, example 2B, example 2C, example 2D, example 2E)

Water evaporation step: heating the acesulfame potassium waste liquid in a reaction kettle until the water content in the residual liquid reaches the preset water content, wherein in the examples 2A, 2B, 2C, 2D and 2E, the specific water content refers to the table 1 to obtain a first material.

A neutralization reaction step: adding excessive liquid ammonia into the reaction kettle, sealing the reaction kettle, and maintaining the reaction kettle for a period of time under the condition of a preset reaction temperature, wherein in the examples 2A, 2B, 2C, 2D and 2E, referring to the table 1, specific reaction time and molar ratio of liquid ammonia to sulfate radical can be obtained, so as to obtain the second material.

And (3) product separation: after the neutralization reaction is finished, cooling to normal temperature, distilling the second material under normal pressure, and distilling out excessive ammonia gas and the solvent remained in the second material; then separating the second material into an organic phase and an aqueous phase; wherein, the organic phase is recovered as a triethylamine crude product; and filtering the water phase to separate solid from liquid to obtain a crude product of ammonium sulfate and a residual liquid.

Comparative example 1 (including comparative example 1A and comparative example 1B)

Water evaporation step: heating the acesulfame potassium waste liquid in a reaction kettle until the water content in the waste liquid reaches the preset water content, wherein in each embodiment comparative example 1, the specific water content refers to table 1 to obtain a first material.

A neutralization reaction step: adding excessive liquid ammonia into the reaction kettle, sealing the reaction kettle, maintaining for a period of time under the condition of a preset reaction temperature, and referring to table 1 in the implementation comparative example 1A, the implementation comparative example 1B and the implementation comparative example 1C for specific reaction time and molar ratio of liquid ammonia to sulfate radicals to obtain a second material.

And (3) product separation: after the neutralization reaction is finished, cooling to normal temperature, distilling the second material under normal pressure, and distilling out excessive ammonia gas and the solvent remained in the second material; then separating the second material into an organic phase and an aqueous phase; wherein, the organic phase is recovered as a triethylamine crude product; and filtering the water phase to separate solid from liquid to obtain a crude product of ammonium sulfate and a residual liquid.

Comparative example 2 (including comparative example 2A and comparative example 2B)

Water evaporation step: heating the acesulfame potassium waste liquid in a reaction kettle until the water content in the waste liquid reaches the preset water content, wherein in the embodiment of comparative example 1, the specific water content refers to table 1 to obtain a first material.

A neutralization reaction step: adding excessive liquid ammonia into the reaction kettle, sealing the reaction kettle, maintaining for a period of time under the condition of a preset reaction temperature, and referring to table 1 for specific reaction time and molar ratio of liquid ammonia to sulfate radical in implementation comparative example 2A and implementation comparative example 2B to obtain a second material.

And (3) product separation: after the neutralization reaction is finished, cooling to normal temperature, distilling the second material under normal pressure, and distilling out excessive ammonia gas and the solvent remained in the second material; then separating the second material into an organic phase and an aqueous phase; wherein, the organic phase is recovered as a triethylamine crude product; and filtering the water phase to separate solid from liquid to obtain a crude product of ammonium sulfate and a residual liquid.

Comparative example 1

There is no moisture evaporation step.

A neutralization reaction step: placing the acesulfame potassium waste liquid into a reaction kettle, adding excessive liquid ammonia into the reaction kettle, sealing the reaction kettle, and maintaining the reaction kettle for a period of time under the condition of a preset reaction temperature, wherein the specific reaction time and the molar ratio of the liquid ammonia to sulfate radicals refer to table 1 to obtain a second material.

And (3) product separation: after the neutralization reaction is finished, cooling to normal temperature, distilling the second material under normal pressure, and distilling out excessive ammonia gas and the solvent remained in the second material; then separating the second material into an organic phase and an aqueous phase; wherein, the organic phase is recovered as a triethylamine crude product; and filtering the water phase to separate solid from liquid to obtain a crude product of ammonium sulfate and a residual liquid.

Table 1:

note: the method for calculating the triethylamine recovery rate comprises the following steps: the molar weight of the recovered triethylamine accounts for the percentage of the molar weight of the triethylamine in the acesulfame potassium waste liquid measured before treatment.

As can be seen from comparative example 1, triethylamine hardly achieves a desirable recovery effect (55%) even after a long reaction time (300min) when the acesulfame potassium waste solution is treated under the condition of normal temperature without evaporating water.

As can be seen from the implementation of comparative example 1A, the water content is evaporated to 70% at normal temperature, and a good recovery effect (79%) can be achieved on triethylamine through a reaction for 300 minutes; from the implementation of the comparative example 1B, if the reaction is carried out for a short time (10min), the conversion rate of triethylamine sulfate is very low, which results in a very low recovery rate (30%) of triethylamine, and an ideal recovery effect cannot be achieved; from the example of comparative example 1A and the example of comparative example 1C, if the water content in the acesulfame potassium waste solution is evaporated to a lower specific degree (20%), under the same conditions, the recovery rate of triethylamine is further improved to 85% than the example of water content of 70%.

From the embodiment of comparative example 1 and the embodiment of comparative example 2, it can be seen that in the case of a relatively high water content (70% or 60%), the reaction temperature is raised to 120 ℃ so that the whole reaction system is boiling, and in a very short time (3min), a high triethylamine recovery rate (75%, 76%) can be achieved.

In example 1, the residual liquid containing triethylamine, which has not reacted completely in comparative example 1B, is distilled until the water content reaches a specific preset range (5% -20%), neutralization reaction is performed at 120 ℃, and then triethylamine is recovered, so that the recovery rate of triethylamine is very high and reaches more than 95%, the reaction time is short (3min), and the waste liquid treatment efficiency can be greatly improved.

Example 2A, example 2B, example 2C and example 2D examined the condition that the water content is the same, different temperature conditions, under 105 ℃, the 10 minutes condition of reaction, the triethylamine recovery rate only reaches 88%, and under 140 ℃ and 160 ℃, the triethylamine recovery rate is slightly reduced on the contrary, this shows that on the basis of 120 ℃, further raising the reaction temperature, not only can not bring beneficial effect, but also can cause the waste of energy, thus increase the waste liquid treatment cost, to the recovery situation of triethylamine. As can be seen from the data, 120 ℃ is a relatively ideal reaction condition.

In conclusion, the reaction time of introducing liquid ammonia at normal temperature is long, and the conversion rate of reaction products is relatively low. Heating under a closed condition, the reaction speed is high, the conversion rate is high, and triethylamine can be effectively recovered. The recovery of triethylamine represents higher economic value on one hand, and reduces the difficulty of subsequent treatment of organic waste on the other hand; after separating triethylamine, the residual waste liquid is continuously recycled, so that the final waste liquid discharge amount is reduced.

While the foregoing is directed to embodiments of the present application, other modifications and variations of the present application may be devised by those skilled in the art in light of the above teachings. It should be understood by those skilled in the art that the foregoing detailed description is for the purpose of better explaining the present application, and the scope of protection of the present application shall be subject to the scope of protection of the claims.

Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.