CN115974204A - Treatment method of waste alkali liquor of aldol condensation reaction - Google Patents

Abstract

The invention relates to a treatment method of waste alkali liquor of aldol condensation reaction, which adjusts the pH of the waste alkali liquor to 6-9 by evaporating and concentrating organic acid generated by aldol condensation side reaction through self-neutralization, separates and recovers an organic phase to be used as a condensation product to return to a condensation device, the neutralized waste alkali liquor is subjected to BP-C type two-chamber bipolar membrane electrodialysis electrolysis treatment, organic acid sodium salt is converted into organic acid and sodium hydroxide, the sodium hydroxide solution is recycled, the organic acid is recovered through extraction and rectification to be sold as a high added value, an extracting agent is recycled, an extraction residual phase is returned to be mixed with the waste alkali liquor for evaporation and concentration to be recycled, condensate is adsorbed, the organic matter is recovered as the condensation product, COD is discharged from waste water, and the waste alkali liquor is treated through condensation _Cr Is less than 500mg/L. The treatment method of the invention does not need to add any additive and carry no impurity, realizes the high-efficiency recovery of organic matters with high added value in the waste alkali liquor of the aldol condensation, the regeneration, the cyclic utilization and the zero discharge of the alkali liquor, and basically realizes the clean production of the aldol condensation.

Description

Treatment method of waste alkali liquor in aldol condensation reaction

Technical Field

The invention relates to a method for treating waste alkali liquor generated in an aldol condensation reaction, in particular to a method for treating waste alkali liquor discharged in the production process of preparing octanol or decanol through butyraldehyde condensation hydrogenation or valeraldehyde condensation hydrogenation.

Background

The existing octanol and decanol production process mainly adopts a propylene, butylene or mixed carbon tetracarbonyl synthesis method. The method comprises the steps of firstly synthesizing butyraldehyde and valeraldehyde by taking propylene, butylene or mixed C4 and synthesis gas as raw materials, and then carrying out condensation reaction on the butyraldehyde and the valeraldehyde under the catalysis of 2% sodium hydroxide to generate octenal and decenal. Octenal and decenal are finally hydrogenated to generate octanol and decanol. And butyraldehyde and valeraldehyde are condensed to produce octenal and decenal, and simultaneously Cannizzaro Reaction (Cannizzaro Reaction) also occurs to produce butyric acid, valeric acid, butanol and pentanol, sodium hydroxide is continuously consumed, and as the butyraldehyde and valeraldehyde are condensed to produce octenal and decenal, water with equal molar quantity is simultaneously produced, the concentration of the alkali liquor is continuously reduced, fresh concentrated alkali liquor needs to be continuously supplemented, and part of alkali liquor is discharged at the same time, and is generally called octanol waste alkali liquor or decanol waste alkali liquor.

The waste lye generally has the following three characteristics: firstly, the alkalinity is strong, and the alkali content is about 1wt% -2 wt%; secondly, the discharge amount is relatively small and is generally only about 1-2 t/h; thirdly, the content of organic matters is high, the composition is complex, and the Chemical Oxygen Demand (COD) is _Cr ) Generally, the concentration is about 40000-100000 mg/L, and the organic acid mainly contains organic matters such as organic acid sodium salt, aldehydes, alcohols, condensed aldehyde, heavy components such as tripolyaldehyde and esters.

A large number of methods are developed at home and abroad aiming at the treatment of waste alkali liquor of aldol condensation, and the methods mainly comprise an acidification extraction method, an acidification-self-extraction method, an acidification thermal separation method, an acidification-extraction-adsorption method, an acidification-fractional-step extraction method, a multi-effect evaporation concentration method, a complex extraction method, a reduced pressure falling film concentration method, an acidification-rectification-electrolysis method, a bipolar membrane electrolysis method and the like.

The Chinese patent CN1220971A adopts acidification-extraction technology to treat the waste alkali liquor. The method comprises acidifying waste alkali solution with inorganic acid, and extracting with C8 or C6 alcohol or C6 hydrocarbon as extractant to obtain COD _Cr The concentration is reduced from 47000mg/L to 9400-35000mg/L，COD _Cr The removal rate reaches 80%, and the extraction phase is rectified to regenerate the extractant for reuse and simultaneously recover organic components. However, the regeneration temperature of the extractant in the method is correspondingly increased along with the increase of the regeneration times, and after the extractant is recycled for 35 times, the regeneration temperature is increased from the initial 180 ℃ to 250 ℃, so that the extractant cannot be recycled indefinitely and needs to be replaced periodically. Meanwhile, the equipment investment and the operating cost of the wastewater treatment are also higher.

The Chinese patent CN1353089A adopts acidification-self-extraction technology to treat octanol waste lye. The technology uses inorganic acid to adjust the pH value of the waste alkali liquor to 2.0-4.5, uses an organic phase separated out after the waste alkali liquor is acidified as an extracting agent, and the volume ratio of the extracting agent to the acidic wastewater is 1:2. After the treatment by the method, oil and COD _Cr The removal rate of the alkali liquor reaches more than 80 percent and 50 percent respectively, most of the difficultly biodegradable substances in the alkali liquor are recovered in the form of an organic phase, and the biodegradation rate of the treated discharge liquor is improved from 40 percent to more than 90 percent. The method has the advantages that the extractant can be directly reused without regeneration, the extraction separation time is short, the process is simple, the investment and the operation cost are both low, and the treated waste liquid is directly discharged into a sewage field for biochemical treatment after neutralization, so that the sewage field is not impacted. The method has been successfully applied to certain petrochemical companies in the north, and certain economic benefits and environmental benefits are obtained. The disadvantage of this process is the COD _Cr The removal rate is low.

CN1530334A uses acidification heat separation technology to treat octanol waste alkali liquor, the method acidifies the waste alkali liquor to pH less than 4.5, heats the emulsion formed after acidification to 95-100 deg.C, the heating time is less than 0.5h, then stands still and stratifies to form oil-water two phase, through setting the outlet height of oil-water two phase, realizes two phase automatic separation, organic phase recycle, the method does not need additional extractant, but COD _Cr The removal rate of the catalyst is only about 50 percent, and the energy consumption is high.

Chinese patent CN1462729A adopts acidification-residual heat self-extraction and activated carbon adsorption to treat waste alkali liquor. The method utilizes the waste heat of the waste waterThe inorganic acid acidifies the waste alkali liquor, product octanol is used as an extracting agent, the extraction raffinate phase is subjected to adsorption treatment by using granular activated carbon, the activated carbon with saturated adsorption is desorbed by low-temperature superheated steam and activated by high-temperature superheated steam for regeneration and recycling, meanwhile, the organic phase is rectified in a rectifying tower of an octanol synthetic process system and separated to recover the product, and the effluent water is neutralized by alkali and then directly enters a biochemical system for treatment to reach the emission standard. The method can be used for treating waste alkali liquor to make COD _Cr The concentration is reduced from 42500mg/L to below 650mg/L, COD _Cr The removal rate reaches more than 98 percent. However, the method has complex process and longer flow, and the operation cost is higher because the additional active carbon needs regeneration and rectification operation; in addition, the method does not consider the problem of recovering the butyric acid component with higher content in the waste alkali liquor, and whether the recovered organic phases are combined and then are merged into a rectifying tower of an octanol synthesis process system for rectification separation or not affects the operation of the device and the quality of main products cannot be determined. Further verification is needed to realize industrialization of the technology.

The Chinese patent CN1403381A develops an acidification-fractional extraction technology on the basis of an acidification-self-extraction technology, and the method adopts C7 and above monoalcohols as extraction agents to extract acidic wastewater after acidification self-extraction treatment and recover butyric acid (or butyrate) therein. The extraction phase is recycled after the back extraction of strong base such as sodium hydroxide or alkaline oxide such as calcium oxide, the back extraction phase is concentrated to recover sodium butyrate, the recovery rate of butyric acid reaches more than 80 percent, and COD in the wastewater is simultaneously enabled to be _Cr And further reduced to about 6000 mg/L. However, the method has a disadvantage that COD in the treated wastewater is caused _Cr Still higher, and butyric acid recovery rate is lower and sodium butyrate quality is not high, and the use value is not big.

Chinese patent CN102730894 (a treatment method of waste alkali liquor produced in a butanol and octanol production device), wang Junmin and the like (treatment of alkali-containing wastewater in octanol production [ J ] environmental science and technology 2009,32 (6): 356-357) adopt a multi-effect evaporation concentration method to treat octanol waste alkali liquor, firstly steam generated in the concentration process is adopted for stripping and removing alcohol, aldehyde and other organic matters in the octanol waste alkali liquor, then organic wastewater mainly containing sodium hydroxide and sodium butyrate is sent into a double-effect evaporator, evaporated and concentrated until the mass content of the sodium butyrate is about 40%, and then the organic wastewater is discharged out of the system through a concentrated alkali liquor delivery pump. Sun Tao (basic high concentration organic wastewater treatment technology and technology research J, qilu petrochemical 2008,36 (2): 97-100) further acidify the concentrated solution to prepare butyric acid and recover sodium sulfate.

CN1065642A adopts reduced pressure evaporation concentration method to treat octanol waste lye, the concentrated alkaline waste water is returned to condensation system, and is reacted again, the evaporated water is treated by steam stripping process, and COD is _Cr Reducing the concentration to below 1000mg/L, condensing the vapor phase part, and performing chromatographic separation to remove organic matters. Industrial practice proves that the application of the patented technology in industry is severely limited because sodium butyrate contained in waste alkali liquor is not removed by the technology, so that more and more sodium butyrate salts are in the system, and finally, crystallization blocks pipelines, so that a condensation reaction system cannot normally operate.

Chinese patent CN201110288711 adopts macroporous adsorption resin as adsorbent to adsorb acidic water phase after acidification and oil removal, COD _Cr Reducing the concentration to below 300mg/L, comprehensively utilizing the adsorbed water or discharging the adsorbed water as waste water, simultaneously regenerating the resin with saturated adsorption by adopting an organic solvent, rectifying and separating desorption liquid to recover the desorption agent and butyric acid, and recycling the desorption agent. The method has good treatment effect, but has large resin consumption, easy loss of organic solvent and higher cost.

US6193872 uses acidification-rectification-electrolysis combined technology to treat octanol waste lye, the method firstly uses inorganic acid to regulate the pH value of waste lye to below 6, recovers separated organic matter, the lower layer aqueous phase is sent to a rectification tower for rectification treatment, the product at the tower top is butyric acid azeotropic liquid, the kettle liquid which basically does not contain organic matter is electrolyzed to obtain inorganic acid and sodium hydroxide solution, the inorganic acid returns to the treatment system for recycling, and is used for acidifying the waste lye produced by the condensation system, and the sodium hydroxide solution is used as catalyst to return to the condensation system for recycling. The method can thoroughly treat octanol waste alkali solution, and realize resource utilization. However, the process is high in capital investment, complex in operating conditions and high in operating cost, is still in a test stage at present, and has no reports of industrial application.

DE 196 04 903 discloses a process for separating alkali metal hydroxide solutions from aldol condensation products, which process follows the principle of three-compartment electrolysis or electrodialysis. In this process, the product is separated in the aqueous phase and passed through the central compartment of the cell bounded by anion and cation exchange membranes. Na in sodium hydroxide solution under the action of electric field ⁺ Ion migration through the cation exchange membrane with OH generated at the cathode ^- The ions combine to form a sodium hydroxide solution in the cathode compartment. OH in the center chamber ^- H migrating through anion exchange membrane into anode chamber and anode region ⁺ Reacting to generate water. In this process, the base is removed from the product in order to separate the sodium hydroxide solution, but the base in the aqueous phase and the organic material has no effect.

A process for recovering sodium hydroxide solution from process water of the above-mentioned type is disclosed in patent WO 92/07648. In this process, a cation exchange membrane is used in order to treat the aqueous phase produced in the aldol condensation reaction. The aqueous phase in this process consists of sodium salts containing organic acids or ethanol, a by-product of the aldol condensation reaction. This solution is accomplished in the anode compartment of a 2-compartment cell. When an electric field is applied, metal cations move to the cathode region and react with hydroxide ions in the cathode region to form sodium hydroxide. In this process, only sodium hydroxide solution was separated as catalyst. In the anode region, the aqueous solution still predominantly comprises organic acids or alcohols. The treatment process of this solution is complex and it cannot be directly fed to the thermal treatment system, since the organic component is still present in the solution in very low concentration. Recovery of low concentrations of organic acids is also not worth mentioning.

US patent 6284116B 1 uses a three-compartment bipolar membrane electrodialysis process to treat this octanol waste lye to separate NaOH and organic acids from the solution, resulting in a completely alkali and organic acid free aqueous solution that can be further utilized or transported to a sewage treatment plant without any treatment. However, the organic acid obtained in this patent contains neutral organic compounds due to migration of neutral organic compounds from the central chamber through the membrane.

Chinese patent CN 108128982A adopts evaporation concentration treatment, evaporation condensate enters a biochemical treatment plant for biochemical treatment, inorganic acid or organic acid is adopted for acidification to adjust the pH value of waste alkali liquor to 1-6, the waste alkali liquor enters a chromatographic device to obtain an organic phase and a water phase, the organic phase enters a rectifying tower, valeric acid is obtained at the top of the rectifying tower, heavy components in the kettle of the rectifying tower enter an incinerator, the water phase enters an evaporation crystallizer to obtain water and solid salt, and the technical scheme that the water returns to a concentration bag device for recycling well solves the problems and can be used for wastewater treatment in a 2-propylheptanol production device. The patent adopts formic acid, acetic acid or propionic acid for acidification, and adds additional organic acid, thereby increasing the treatment difficulty and having stronger corrosivity.

By comprehensively analyzing the results and losses of the methods, the method can be seen that although the prior resource treatment methods of the aldol condensation waste alkali liquor are many and have characteristics, a treatment method which is environment-friendly and has high economic benefit cannot be found. Although the acidification method is the simplest, most economical and most effective method for removing oil substances in the aldol condensation waste alkali liquor, organic acid with high added value in the waste alkali liquor is difficult to recover, and the existing extraction technology also cannot achieve ideal effect; the evaporation concentration method and the rectification method have good effects, but have high treatment cost, and the sodium butyrate recovered by the concentration method has poor quality and is difficult to purify; the rectification method can only obtain organic acid azeotropic liquid containing water, and no related technical report of further concentration and purification exists at present; the acidification-macroporous resin adsorption method has large resin consumption and high investment cost, and the organic solvent used as the desorption agent is easy to lose. Therefore, the treatment of the waste alkali liquor of the aldol condensation is difficult to realize simply, economically and effectively by adopting any method, the recovery of organic acid with high added value and the regeneration and recycling of the alkali liquor are realized, and the recovery treatment cost is the difficult point of the treatment of the waste alkali liquor.

Disclosure of Invention

The invention aims to solve the problems and provides a method for treating waste alkali liquor of aldol condensation reaction, which does not need to add substances, adopts byproduct organic acid generated by aldol condensation side reaction to neutralize the waste alkali liquor, does not need to add a neutralizing agent, avoids the impurity brought by the added neutralizing agent, electrolyzes the neutralized waste alkali liquor by adopting BP-C type two-chamber bipolar membrane electrodialysis to obtain regenerated alkali liquor sodium hydroxide for recycling, simultaneously adopts alcohol of a condensation hydrogenation product to extract an organic acid water phase obtained by electrolysis, and extracts an organic phase for rectification treatment to separate and recover light components such as aldehydes, organic acid and an extracting agent; recovering the light component as an aldol condensation reaction product; part of organic acid is used as a neutralizer of the waste alkali liquor, and the rest part is used as a high value-added product to be recycled and sold; the extractant is recycled, so that the aims of full recovery of organic matters and zero discharge of waste alkali liquor are fulfilled, pollution is avoided, and clean production is basically realized.

In order to achieve the purpose, the invention provides a method for treating waste alkali liquor of aldol condensation reaction, which adopts organic acid to carry out neutralization and acidification treatment on the waste alkali liquor, and specifically comprises the following steps:

step (1): evaporating and concentrating the waste alkali liquor to obtain concentrated waste alkali liquor, adsorbing the evaporated condensate to recover organic matters in the evaporated condensate, and discharging or comprehensively utilizing the adsorbed condensate as waste water;

step (2): cooling and concentrating the waste alkali liquor, adding organic acid for neutralization and acidification, and adjusting the pH to be less than 9 to obtain neutralized waste alkali liquor; demulsifying and layering, separating to obtain an upper organic phase and a lower water phase, washing the upper organic phase with waste alkali liquor, and recovering and treating the upper organic phase as a condensation product;

and (3): performing bipolar membrane electrodialysis treatment on the lower-layer water phase in the step (2) to obtain regenerated alkali liquor and a water phase rich in organic acid, wherein the regenerated alkali liquor is used as a catalyst for the aldol condensation reaction for recycling;

and (4): extracting the organic acid-rich water phase obtained in the step (3) by using a condensation hydrogenation product of the aldol condensation reaction to obtain an extracted organic phase and a raffinate phase; rectifying and separating the extracted organic phase to obtain a light component, an organic acid and an extracting agent, and recycling the extracting agent; returning the light components and raffinate phase to the step (1) for circular treatment.

The waste alkali liquor of the invention is butyraldehyde condensation waste alkali liquor or valeraldehyde condensation waste alkali liquor.

In the step (2), the organic acid is a side reaction product of the aldol condensation reaction, for example, butyraldehyde condensation waste alkali liquor is neutralized by butyric acid, and valeraldehyde condensation waste alkali liquor is neutralized by valeric acid; or neutralizing the organic acid obtained by the rectification and separation of the organic phase extracted in the step (4).

In the step (2), the demulsification layering treatment is gravity settling layering demulsification treatment or self-extraction treatment. The demulsification layering treatment can remove heavy components such as emulsified aldehydes, condensation products and the like in the waste alkali liquor to obtain a salt solution with the main component of organic sodium.

When the demulsification layering treatment is gravity settling layering demulsification treatment, the separation residence time of the gravity settling layering demulsification treatment is 0.5-8 h.

Preferably, the separation residence time of the gravity settling layering demulsification treatment is 1-4 h.

When the demulsification layering treatment is self-extraction treatment, the extractant for the self-extraction treatment is the organic phase of the aldol condensation reaction or the upper organic phase obtained by the separation in the step (2).

The volume ratio of the extracting agent to the neutralized waste alkali liquor in the self-extraction treatment is 0.1; the separation residence time of the self-extraction treatment is 0.2 to 4 hours.

Preferably, the volume ratio of the extracting agent to the neutralized waste lye from the extraction treatment is 0.5; the separation residence time of the self-extraction treatment is 0.5 to 1 hour.

In the step (2), the upper organic phase is used as a condensation product and is recovered by a separation process of a product returned to the aldol condensation reaction, or is washed by waste alkali liquor to remove trace organic acid in the waste alkali liquor and then is recovered as the aldol condensation product, or is used as an extracting agent for demulsification and layering treatment.

In the step (3), a BP-C type two-chamber bipolar membrane electrodialysis device is adopted in bipolar membrane electrodialysis treatment.

In the step (3) of the present invention, the mass concentration of the regenerated alkali solution is 1wt% to 15wt%, preferably 2wt% to 8wt%. The regenerated alkali liquor can be used as a catalyst for aldol condensation reaction or supplemented alkali liquor for recycling.

In the step (4), the extractant in the aqueous phase extraction treatment process rich in organic acid is a condensation hydrogenation product of aldol condensation reaction, that is, octanol is adopted as the extractant in butyraldehyde condensation waste alkali liquor, and decanol is adopted as the extractant in valeraldehyde condensation waste alkali liquor, so that the difficulty of subsequent separation and the treatment cost are reduced.

In the step (4), the volume ratio of the extractant to the organic acid-rich aqueous phase in the extraction treatment process of the organic acid-rich aqueous phase is 0.1-2:1, the separation residence time is 0.2-4 h, the extraction stages are 1-4 times, and the countercurrent is applied stage by stage.

Preferably, the volume ratio of the extractant to the organic acid-rich aqueous phase in the extraction treatment process of the organic acid-rich aqueous phase is 0.5-1.5.

In the step (4), the light components are recovered as the product of the aldol condensation reaction, the light components such as raw material aldehyde, organic acid and the extracting agent can be separated, wherein the light components such as the raw material aldehyde are recovered, the organic acid is sold as a product with high added value, and the extracting agent is recycled.

In the step (4), the raffinate phase returns to the step (1) and is mixed with the waste alkali liquor for evaporation concentration and recycling treatment.

The step (4) can remove most of organic acid, dissolved alcohols and condensation products in the water phase to ensure that COD in the water phase _Cr Reducing to 4000-8000 mg/L, wherein the step can be performed in countercurrent for multiple times, the extraction number is 1-4 times, preferably 2-3 times, and COD in water phase _Cr The concentration is reduced to 2000-4000 mg/L.

It should be noted that trace heavy components dissolved in the waste alkali liquor inevitably accumulate in the extractant, but experiments prove that the extractant can be reused for more than 150 times, and the extraction efficiency is hardly reduced.

Certainly, the extractant can not be used for unlimited times, when the extraction efficiency is reduced to 90% through detection, the extractant is replaced, the invalid extractant is washed by waste alkali liquor or fresh alkali liquor and then used as a condensation product to return to a system for recycling, and loss can not be caused.

The extracted water phase is returned to the device and mixed with the waste alkali liquor to be evaporated and concentrated together, so that all products can be conveniently recovered.

Of course, the extracted water phase can also be directly discharged into a sewage treatment plant for biological treatment, and no adverse effect is caused on the biological treatment device.

In the step (1) of the invention, the evaporation concentration uses electric heating, steam heating or condensation reaction discharging as a heat source.

In the step (1) of the invention, the adsorbent for the adsorption treatment of the evaporative condensate is macroporous adsorption resin.

Preferably, in step (1) of the present invention, the adsorbent for the evaporative condensate adsorption treatment is a neutral or weakly basic macroporous adsorption resin.

The evaporation condensate adsorbs and recovers organic matters in the waste alkali liquor to ensure that the effluent COD _Cr The concentration is reduced to below 500mg/L.

After the neutral or weakly alkaline macroporous adsorption resin is adsorbed and saturated, alkali liquor with the mass concentration of 1-4 wt% is used for regeneration or steam heating regeneration, and regenerated liquid is obtained.

The regenerated liquid returns to the step (1) and is mixed with the waste alkali liquor for circular treatment.

The invention can also be detailed as follows:

(1) Evaporating and concentrating the waste alkali liquor by 1-2 times, and adsorbing and recovering organic matters in the evaporated condensate by adopting neutral macroporous adsorption resin to ensure that the effluent COD _Cr The concentration is reduced to below 500mg/L. The neutral adsorption resin with saturated adsorption is regenerated by alkali liquor with the mass concentration of 1-4 wt% or heated by steam, and the regenerated liquid is returned to the device to be mixed with waste alkali liquor for cyclic treatment.

(2) After the concentrated alkali liquor is cooled, organic acid generated by side reaction of aldol condensation is adopted to neutralize and adjust the pH value of the waste alkali liquor to be less than 9, for example, butyraldehyde condensation waste alkali liquor is neutralized by butyric acid, and valeraldehyde condensation waste alkali liquor is neutralized by valeric acid.

Standing the neutralized waste alkali liquor, and carrying out gravity settling layering to obtain an organic phase and a water phase, separating the upper organic phase from the lower water phase, and recovering the upper organic phase; the separation retention time is 0.5-8 h, and the optimal separation time is 1-4 h.

Or the self-extraction treatment is carried out on the neutralized waste alkali liquor by adopting a condensation product, the layering time is shortened, the self-extraction extractant is a condensation reaction organic phase or an organic phase for demulsification and layering separation, the volume ratio of the extractant to the neutralized waste alkali liquor is 0.1-2:1, the optimal proportion is 0.5.

The step can realize demulsification of the waste alkali liquor, so that heavy components such as emulsified aldehydes, condensation products and the like in the waste alkali liquor are removed, and the organic acid sodium salt solution is obtained.

(3) And performing bipolar membrane electrodialysis treatment on the demulsified lower-layer water phase to obtain regenerated alkali liquor and a water phase rich in organic acid, wherein the regenerated alkali liquor is used as a catalyst for recycling.

The bipolar membrane electrodialysis treatment adopts a BP-C type two-chamber bipolar membrane electrodialysis device, the mass concentration of the obtained regenerated alkali liquor is 1-15 wt%, and the optimal mass concentration is 2-8 wt%, and the regenerated alkali liquor is recycled as supplementary alkali liquor.

The organic acid-rich water phase obtained by discharging in the salt chamber of the BP-C type two-chamber bipolar membrane electrodialysis device adopts a corresponding raw material condensation hydrogenation product as an extracting agent, the butyraldehyde condensation adopts an octanol extracting agent, and the valeraldehyde condensation adopts decanol as an extracting agent, so that the difficulty of subsequent separation and the treatment cost are reduced.

In the process of extracting the organic acid-rich water phase, the volume ratio of the extracting agent to the organic acid-rich water phase is 0.1-2:1, the optimal ratio is 0.5.

The light components separated by the rectification of the extracted organic phase are recovered as condensation products, the light components such as raw material aldehyde, organic acid and an extracting agent can be separated, wherein the light components such as the raw material aldehyde are recovered, the organic acid is sold as a product with high added value, and the extracting agent is recycled.

Compared with the prior art, the treatment method of the invention solves the defects of the prior art and has the following remarkable advantages:

1. the waste alkali liquor is neutralized by using the byproduct organic acid generated by the aldol condensation reaction, and the addition of inorganic acid or other organic acid is avoided, so that the introduction of impurities is avoided, the difficulty of subsequent separation is reduced, and high-added-value organic acid, condensation products and the like such as butyric acid, valeric acid and the like can be recovered.

2. The organic acid sodium salt is obtained by adopting two-chamber bipolar membrane electrodialysis treatment for neutralization, and simultaneously, the water phase rich in organic acid and regenerated alkali liquor are obtained, so that the cyclic utilization of the alkali liquor is realized, the discharge of waste alkali liquor is avoided, and the clean production is realized to the maximum extent (because of the reaction of generating water, the discharge of waste water is inevitable).

3. COD of discharged wastewater _Cr The concentration is lower than 500mg/L, the water inlet requirement of a sewage treatment plant is met, and no adverse effect is caused to the biological sewage treatment plant.

Drawings

FIG. 1 is a process flow diagram of the condensation spent lye treatment of the present invention.

Wherein, the reference numbers:

1: an evaporation concentrator; 2: acidifying the oil removal tank; 3: bipolar membrane electrodialysers; 4: an extractor; 5: a rectifying tower; 6: an organic acid storage tank; 7: an adsorption tower; 8: a sewage biological treatment device; 9: and regenerating an alkali liquor storage tank.

Detailed Description

The present invention is described in detail below by way of examples, it should be noted that the examples are only for the purpose of further illustration, and are not to be construed as limiting the scope of the present invention, and that various insubstantial modifications and adaptations can be made by those skilled in the art in light of the above teachings.

Example 1

Taking 1L sodium valerate with mass concentration of 4wt%, sodium hydroxide with mass concentration of 1.8wt%, COD _Cr 102900mg/L valeraldehyde condensation waste alkali liquor, stirring, adding valeric acid for neutralization to pH =9, standing for 2h to obtain a layered solution, recovering and treating an upper layer organic phase, and collecting a lower layer water phase; the lower aqueous phase is detected to be 8.9wt% sodium valerate solution, COD _Cr Is 183650mg/L.

And (3) electrolyzing the separated lower-layer water phase by adopting a two-chamber BP-C type bipolar membrane electrodialyzer to obtain regenerated alkali liquor with the mass concentration of 2.2wt% of sodium hydroxide and the mass of 0.1wt% of sodium valerate and a water phase rich in valeric acid.

Extracting the water phase rich in valeric acid with decanol at a volume ratio of 1:1 for 1 hr, standing for 1 hr, separating the lower raffinate phase, i.e. water phase, from the upper extract phase, and determining that the lower raffinate phase, i.e. water phase valeric acid mass concentration is 0.23wt%, and COD is _Cr 5562mg/L.

Rectifying the upper extraction phase, and respectively collecting light components (water) with the boiling point less than 179 ℃ and valeric acid with the boiling point of 179-181 ℃, wherein the purity of the valeric acid is 98.7 percent.

Example 2

Taking 4wt% of 2L sodium valerate, 1.8wt% of sodium hydroxide and COD _Cr Evaporating and concentrating 102900mg/L valeraldehyde condensation waste alkali liquor to 1L, stirring, adding valeric acid to neutralize to pH =9, standing for 2h to obtain a layered solution, recovering an upper organic phase, and collecting a lower aqueous phase; the lower aqueous phase is detected to be 13.8 percent sodium valerate solution, COD _Cr Is 287300mg/L.

Adopting 100mL Innovate-15 macroporous adsorption resin to carry out adsorption treatment on the effluent of the evaporation condensate, wherein the influent COD (chemical oxygen demand) _Cr 6327mg/L, the adsorption flow rate is 1BV/h (volume of resin/h), the adsorption temperature is 40 ℃, and the COD in the effluent is adsorbed _Cr It was 129mg/L.

And (3) electrolyzing the lower-layer water phase by using a two-chamber BP-C type bipolar membrane electrodialyzer to obtain regenerated alkali liquor with the sodium hydroxide concentration of 4.3wt% and sodium valerate concentration of 0.11wt% and a water phase rich in valeric acid.

Extracting with fresh decanol at a volume ratio of 1:1 for 1 hr under stirring, standing for 1 hr, separating lower extractive raffinate phase (water phase) and upper extractive phase, and measuring the content of lower extractive raffinate phase (water phase valeric acid) to be 0.2wt%, COD _Cr 6985mg/L.

Performing secondary extraction treatment on the raffinate phase by using 250mL of fresh decanol, stirring and mixing for 1h, standing for 1h, and measuring that the valeric acid in the lower water phase is 0.11wt%, and the COD is _Cr 2623mg/L.

Collecting the upper extraction phase, rectifying, and respectively collecting light components (water) with the boiling point less than 179 ℃ and valeric acid with the boiling point of 179-181 ℃, wherein the purity of the valeric acid is 99.2 percent.

Example 3

Collecting 250mL of raffinate of example 2, extracting with the secondary extraction of example 2, stirring and mixing for 1 hr, standing for 2 hr, separating lower raffinate phase (water phase) and upper extract phase, and determining that lower raffinate phase (water phase) contains 0.13wt% of pentanoic acid and COD _Cr Is 3585mg/L.

Example 4

Taking 4.5wt% of 1L sodium butyrate, 1.9wt% of sodium hydroxide and COD _Cr The solution is 98600mg/L butyraldehyde condensation waste alkali liquor, stirring, adding butyric acid for neutralization until the pH is =8.6, standing for 2 hours to obtain a layered solution, recovering and treating an upper organic phase, and collecting a lower aqueous phase; the detection shows that the concentration of the sodium butyrate in the lower aqueous phase is 9.8wt%, and the COD is _Cr Is 188100mg/L.

And (3) electrolyzing the lower aqueous phase by using a two-chamber BP-C type bipolar membrane electrodialyzer to obtain 4.6wt% of sodium hydroxide, 0.15wt% of regenerated alkali liquor of sodium butyrate and an aqueous phase rich in butyric acid.

Adding 250mL octanol into 250mL aqueous phase rich in butyric acid for extraction treatment, stirring and mixing for 1h, standing for 1h, separating lower raffinate phase, namely aqueous phase and upper extract phase, and determining that the content of butyric acid in the lower raffinate phase aqueous phase is 0.55wt%, and the content of COD is 0.55wt% _Cr 13236mg/L, and extracting the raffinate phase with fresh octanol for the second time, COD _Cr Reducing to 6946mg/L, performing third extraction on raffinate phase with fresh octanol, and collecting raffinate phase COD _Cr The concentration is reduced to 4892mg/L.

Collecting the upper extraction phase, rectifying, and respectively collecting light component (containing water) with boiling point less than 162 deg.C and butyric acid with boiling point of 162-164 deg.C, and determining that the purity of butyric acid is 98.7%.

In conclusion, the waste alkali liquor is neutralized by using the byproduct organic acid generated by the aldol condensation reaction, so that the addition of inorganic acid or other organic acids is avoided, and high-value-added organic acid, condensation products and the like such as butyric acid and valeric acid can be recovered; electroosmosis using two-chamber bipolar membraneThe sodium salt of the organic acid is obtained by precipitation and neutralization, and simultaneously the water phase rich in the organic acid and the regenerated alkali liquor are obtained, so that the cyclic utilization of the alkali liquor is realized; after secondary or tertiary extraction, the waste water COD _Cr The concentration is lower than 5000mg/L, because the extractant is produced by a condensation system and has no additional components, the raffinate phase, namely the water phase, can be returned to be mixed with the waste alkali liquor for circular treatment, and the evaporated condensate is adsorbed by macroporous resin, and COD is obtained _Cr Less than 500mg/L, meets the water inlet requirement of a sewage treatment plant, can be directly discharged into a sewage biological treatment plant for treatment, and does not cause any adverse effect on the biological sewage treatment plant.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that all such changes and modifications as fall within the true spirit and scope of the invention as defined by the appended claims be interpreted in accordance with the breadth to which they are fairly, if not explicitly recited herein.

Claims (22)

1. A method for treating waste alkali liquor of aldol condensation reaction is characterized in that organic acid is adopted to carry out neutralization and acidification treatment on the waste alkali liquor, and the method specifically comprises the following steps:

step (1): evaporating and concentrating the waste alkali liquor to obtain concentrated waste alkali liquor, adsorbing the evaporated condensate to recover organic matters in the evaporated condensate, and discharging or comprehensively utilizing the adsorbed condensate as waste water;

step (2): cooling and concentrating the waste alkali liquor, adding organic acid for neutralization and acidification, and adjusting the pH to be less than 9 to obtain neutralized waste alkali liquor; demulsifying and layering, separating to obtain an upper organic phase and a lower water phase, and washing the upper organic phase with waste alkali liquor to be used as a condensation product for recycling;

and (3): performing bipolar membrane electrodialysis treatment on the lower-layer water phase in the step (2) to obtain regenerated alkali liquor and an organic acid-rich water phase, wherein the regenerated alkali liquor is used as a catalyst for the aldol condensation reaction for recycling;

and (4): extracting the organic acid-rich water phase obtained in the step (3) by adopting a condensation hydrogenation product of the aldol condensation reaction to obtain an extracted organic phase and a raffinate phase; rectifying and separating the extracted organic phase to obtain a light component, an organic acid and an extractant, and recycling the extractant; returning the light components and raffinate phase to the step (1) for circular treatment.

2. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 1, wherein the waste alkali liquor is butyraldehyde condensation waste alkali liquor or valeraldehyde condensation waste alkali liquor.

3. The method for treating waste lye of aldol condensation reaction as set forth in claim 1 wherein in said step (2), the organic acid is butyric acid or valeric acid which is a by-product of said aldol condensation reaction, or the organic acid obtained by the rectification separation of the organic phase extracted in said step (4).

4. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 1, wherein in the step (2), the demulsification and stratification treatment is gravity settling and stratification demulsification treatment or self-extraction treatment.

5. The method for treating the waste alkali liquor generated in the aldol condensation reaction of claim 4, wherein the demulsification and stratification treatment is a gravity settling and stratification demulsification treatment, and the separation residence time of the gravity settling and stratification demulsification treatment is 0.5-8 h.

6. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 5, wherein the separation residence time of the gravity settling layering demulsification treatment is 1-4 h.

7. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 4, wherein the demulsification layering treatment is a self-extraction treatment, and the extractant of the self-extraction treatment is the organic phase generated in the aldol condensation reaction or the upper organic phase separated in the step (2).

8. The method for treating the waste alkali liquor generated in the aldol condensation reaction of claim 7, wherein the volume ratio of the extracting agent subjected to the self-extraction treatment to the neutralized waste alkali liquor is 0.1 to 2:1; the separation residence time of the self-extraction treatment is 0.2 to 4 hours.

9. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 8, wherein the volume ratio of the extractant subjected to self-extraction to the neutralized waste alkali liquor is 0.5 to 1.5; the separation residence time of the self-extraction treatment is 0.5 to 1 hour.

10. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 1, wherein in step (2), the upper organic phase is recovered and treated as a condensation product by a separation process of returning to the product of aldol condensation reaction, or is recovered as an aldol condensation product after washing the waste alkali liquor to remove trace organic acids therein, or is used as an extractant for demulsification and layering treatment.

11. The method for treating waste alkali liquor of aldol condensation reaction according to claim 1, wherein in the step (3), bipolar membrane electrodialysis is performed using a bipolar membrane electrodialysis device of a BP-C type two-compartment type.

12. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 1, wherein in step (3), the concentration of the regenerated alkali liquor is 1-15 wt%, preferably 2-8 wt%.

13. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 2, wherein in step (4), the extractant used in the extraction treatment of the organic acid-rich aqueous phase is the product of condensation hydrogenation of the aldol condensation reaction, the butyraldehyde condensation waste alkali liquor uses octanol as the extractant, and the valeraldehyde condensation waste alkali liquor uses decanol as the extractant.

14. The method for treating the waste alkali liquor generated in the aldol condensation reaction of step (4), wherein the volume ratio of the extracting agent in the extraction treatment process of the organic acid-rich aqueous phase to the organic acid-rich aqueous phase is 0.1-2:1, the separation residence time is 0.2-4 h, and the extraction stages are 1-4 times and are carried out by gradually applying counter-current.

15. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 14, wherein the volume ratio of the extractant to the organic acid-rich aqueous phase in the extraction treatment of the organic acid-rich aqueous phase is 0.5 to 1.5, the separation retention time is 0.5 to 2 hours, and the number of extraction stages is 2 to 3.

16. The method for treating waste lye of aldol condensation reaction as claimed in claim 1 wherein in step (4) light components are recovered as the product of the aldol condensation reaction and organic acids are recycled as high value added products and the extractant.

17. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 1, wherein in the step (4), the raffinate is returned to the step (1) and mixed with waste alkali liquor to be concentrated by evaporation.

18. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 1, wherein in step (1), the evaporation and concentration are performed by using electric heating, steam heating or discharging of condensation reaction as a heat source.

19. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 1, wherein in step (1), the adsorbent used in the adsorption treatment of the evaporative condensate is a macroporous adsorbent resin.

20. The method for treating waste alkali liquor generated in aldol condensation reaction of step (1), wherein the adsorbent used in the adsorption treatment of the evaporative condensate in step (1) is neutral or weakly alkaline macroporous adsorbent resin.

21. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 20, wherein after the neutral or weakly alkaline macroporous adsorption resin is saturated by adsorption, the regenerated solution is obtained by regenerating with 1-4 wt% alkali liquor or heating with steam.

22. The method for treating waste alkali liquor generated in aldol condensation reaction of claim 21, wherein the regeneration liquid is returned to step (1) and mixed with waste alkali liquor for recycling treatment.

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