CN105712427A - Extracting agent with high partition coefficient for polyphenol in phenol wastewater and extracting method - Google Patents

Abstract

The invention belongs to the technical field of sewage treatment, and discloses an extraction agent and an extraction method with a high distribution coefficient for polyphenols in phenol-containing wastewater. The method is as follows: using methyl isobutyl ketone as the main extractant and toluene as the synergistic extractant, wherein the volume fraction of methyl isobutyl ketone is 90% to 95%, and the volume fraction of toluene is 5% to 10%, and then the Phenol wastewater is subjected to multistage countercurrent extraction with this composite extractant at a temperature of 25-70°C to obtain an extract phase and a raffinate phase. The composite extractant of the present invention greatly improves the extraction effect of polyphenols, and the polarity and boiling point of toluene and methyl isobutyl ketone in the composite extractant are close, the solvent loss is smaller, the recovery cycle is convenient, and it has good performance in actual industrial application. Prospects.

Description

A kind of extraction agent and extraction method with high partition coefficient for polyphenols in phenolic wastewater

technical field

The invention belongs to the technical field of sewage treatment, and in particular relates to an extraction agent with a high distribution coefficient for polyphenols in phenol-containing wastewater and an extraction method.

Background technique

Lurgi gasification, BGL gasification, coal low-temperature dry distillation, coal tar hydrogenation and other processes produce high-concentration phenol-containing wastewater in processes such as cooling, washing and purification. The water quality components are complex, and the content of unit phenols and polyphenols is high. , biochemical treatment is difficult. At present, solvent extraction is generally used to remove phenolic substances in wastewater when treating such phenol-containing wastewater. The key to the implementation of extraction and dephenolization of coal gasification wastewater is to first select a suitable extraction agent, extraction conditions and extraction method. Stages, so as to determine the reasonable wastewater dephenolization process, organic matter recovery and extraction agent regeneration methods, and extraction equipment. At present, the extraction agents for the extraction and treatment of phenolic substances in this type of wastewater mainly include diisopropyl ether, methyl isobutyl ketone, and medium oil, while diisopropyl ether and methyl isobutyl methyl ketone are more commonly used in industry. ketone. Compared with other extractants such as diisopropyl ether, methyl isobutyl ketone has a higher extraction distribution coefficient for unit phenols, and has been very maturely used in industry, but its extraction distribution coefficient for polyphenols is lower. The extraction of polyphenols is not good. For high-concentration phenol-containing wastewater, it is necessary to develop an extractant with a high partition coefficient for polyphenols.

Contents of the invention

In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide an extractant with a high partition coefficient for polyphenols in phenol-containing wastewater.

Another object of the present invention is to provide a method for extracting phenol-containing wastewater by using the above-mentioned extractant.

The object of the invention is achieved through the following technical solutions:

An extractant with a high partition coefficient for polyphenols in phenol-containing wastewater, the extractant is composed of a main extractant methyl isobutyl ketone with a volume fraction of 90% to 95% and a synergistic extractant with a volume fraction of 5% to 10%. The extractant consists of toluene.

A method for extracting phenol-containing wastewater by using the above-mentioned extractant, comprising the steps of:

Methyl isobutyl ketone is used as the main extractant, and toluene is used as a synergistic extractant, wherein the volume fraction of methyl isobutyl ketone is 90% to 95%, and the volume fraction of toluene is 5% to 10%, and then the phenol-containing wastewater is compounded with this The extractant is subjected to multistage countercurrent extraction at a temperature of 25-70° C. to obtain an extract phase and a raffinate phase.

Preferably, the phenol-containing wastewater refers to high-concentration phenol-containing wastewater with a polyphenol content of not less than 5000 mg/L; The total phenol content in the phenol-containing wastewater is more preferably 8000-18000 mg/L.

Preferably, the phenol-containing wastewater is phenol-containing coal chemical wastewater; the polyphenol content in the phenol-containing coal chemical wastewater is 5000-10000 mg/L, and the unit phenol content is 3000-8000 mg/L.

Preferably, the volume ratio of the composite extractant to phenol-containing wastewater is 1:(2-7).

Preferably, the extraction refers to the extraction under the condition of pH 6-9; more preferably the extraction under the condition of pH 6-7.

Preferably, in the multistage countercurrent extraction process, the mixing time is 30 minutes and the resting time is 15 minutes.

Before using the composite extractant to extract the phenol-containing wastewater, it also includes the pretreatment process of removing oil, removing suspended solids, deacidification and deammonification of the phenol-containing wastewater.

After the compound extractant is used to extract the phenol-containing wastewater, the raffinate phase enters the solvent stripping tower to strip and recover the extractant, and the purified water is sent to biochemical treatment; the extract phase enters the rectification tower to rectify and recover crude phenol and Extractant, the recovered extractant is recycled.

The principle of the present invention is: coal gasification wastewater contains a variety of organic substances, in order to determine the impact of the presence of various organic substances on the extraction of phenolic substances by the extractant (playing a role in promoting or inhibiting), the organic substances in the wastewater were qualitatively analyzed and determined Several typical organic substances in wastewater, and whether the existence of these organic substances have any effect on the extraction of phenolic substances by methyl isobutyl ketone. As a result, it was found that toluene significantly improved the effect of extracting polyphenols from methyl isobutyl ketone in a suitable concentration range. Further, through repeated experiments and tests, it was determined that under certain extraction conditions (temperature, pH), toluene and methyl isobutyl ketone Under the appropriate concentration ratio, butyl ketone can significantly improve the effect of the extractant polyphenol. At the same time, the boiling point of toluene (111° C.) is close to that of methyl isobutyl ketone (116° C.), and their solubility in water is close, so they are easy to recover and recycle at the same time.

The preparation method of the present invention and the resulting product have the following advantages and beneficial effects:

(1) Compared with the original extractant, the composite extractant of the present invention has greatly improved the extraction effect on polyphenols, and provides a better environment for subsequent biochemical treatment.

(2) in the composite extractant of the present invention, the polarity of toluene and methyl isobutyl ketone is close, and the solubility in water is smaller, and solvent loss is smaller.

(3) the boiling point of toluene and methyl isobutyl ketone is close in the composite extractant of the present invention, reclaims and recycles simultaneously.

(4) The phenol-containing coal chemical industry wastewater contains toluene, and the composite extractant of the present invention is used to treat the phenol-containing coal chemical industry wastewater, and a part of toluene in the wastewater can be utilized, so that local materials can be obtained to reduce the amount of extractant, and at the same time, it is convenient for subsequent treatment Centralized recycling of toluene.

(5) The compound extractant based on methyl isobutyl ketone of the present invention has little change to the operating conditions of the equipment in actual industrial application, and is conducive to rapid application in the extraction and dephenolization process.

detailed description

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

The phenol content in the following examples is determined by the following method:

The components were analyzed by gas chromatography with a 30m×0.32mm×0.25μm DB-5MS capillary column and a hydrogen flame ion detector (FID). Using the internal standard method, the internal standard substance of MIBK is ethanol, and the internal standard substance of phenolic substances is octanol. The injector and detector temperatures were 270°C and 230°C, respectively. The initial temperature of the column oven was set at 110°C, and after keeping for 2 minutes, it was raised to 160°C at 10°C/min. The carrier gas used was nitrogen with a flow rate of 30ml/min.

Example 1

90% methyl isobutyl ketone and 10% toluene are formulated into a compound extractant by volume ratio; the total phenol content is 8000mg/L, wherein the unit phenol content is 3000mg/L, and the polyphenol content is 5000mg/L The temperature of phenol-containing coal chemical industry wastewater is controlled at 25°C, and the pH value is adjusted to 6; then, the above-mentioned composite extractant and phenol-containing wastewater are subjected to four-stage countercurrent extraction in 4 separating funnels at a volume ratio of 1:4. Wherein mixed for 30 minutes, standing for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 144 mg/L and 365 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 11425 mg/L and 18538 mg/L respectively. From this, it can be calculated that 95.21% of unit phenols and 92.69% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

Example 2

According to the volume ratio, 95% methyl isobutyl ketone and 5% toluene are formulated into a composite extractant; the total phenol content is 18000mg/L, wherein the unit phenol content is 8000mg/L, and the polyphenol content is 10000mg/L The temperature of phenol-containing coal chemical industry wastewater is controlled at 25°C, and the pH value is adjusted to 6; then, the above-mentioned composite extractant and phenol-containing wastewater are subjected to four-stage countercurrent extraction in 4 separating funnels at a volume ratio of 1:4. Wherein mixed for 30 minutes, standing for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 331 mg/L and 605 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 19172 mg/L and 37580 mg/L respectively. From this, it can be calculated that 95.86% of unit phenols and 93.95% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

Example 3

According to the volume ratio, 95% methyl isobutyl ketone and 5% toluene are formulated into a composite extractant; the total phenol content is 8000mg/L, wherein the unit phenol content is 3000mg/L, and the polyphenol content is 5000mg/L. The temperature of phenol-containing coal chemical industry wastewater is controlled at 25°C, and the pH value is adjusted to 6; then, the above-mentioned composite extractant and phenol-containing wastewater are subjected to four-stage countercurrent extraction in 4 separating funnels at a volume ratio of 1:4. Wherein mixed for 30 minutes, standing for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 123 mg/L and 319 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 11506 mg/L and 18722 mg/L respectively. It can be calculated that 95.89% of unit phenols and 93.61% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

Example 4

90% methyl isobutyl ketone and 10% toluene are formulated into a compound extractant by volume ratio; the total phenol content is 10000mg/L, wherein the unit phenol content is 4000mg/L, and the polyphenol content is 6000mg/L The temperature of phenol-containing coal chemical wastewater is controlled at 25°C, and the pH value is adjusted to 7; then, the above-mentioned composite extractant and phenol-containing wastewater are subjected to four-stage countercurrent extraction in 4 separating funnels at a volume ratio of 1:2. Wherein mixed for 30 minutes, standing for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 118 mg/L and 280 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 7763 mg/L and 11439 mg/L respectively. It can be calculated that 97.04% of unit phenols and 95.33% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

Example 5

According to the volume ratio, 95% methyl isobutyl ketone and 5% toluene are formulated into a composite extractant; the total phenol content is 14000mg/L, wherein the unit phenol content is 6000mg/L, and the polyphenol content is 8000mg/L. The temperature of phenol-containing coal chemical wastewater is controlled at 70°C, and the pH value is adjusted to 7; then, the above-mentioned composite extractant and phenol-containing wastewater are subjected to four-stage countercurrent extraction in 4 separating funnels at a volume ratio of 1:7. Wherein mixed for 30 minutes, standing for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 375 mg/L and 678 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 39370 mg/L and 51307 mg/L respectively. It can be calculated that 93.74% of unit phenols and 91.62% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

Example 6

90% methyl isobutyl ketone and 10% toluene are formulated into a compound extractant by volume ratio; the total phenol content is 8000mg/L, wherein the unit phenol content is 3000mg/L, and the polyphenol content is 5000mg/L The temperature of phenol-containing coal chemical wastewater is controlled at 25°C, and the pH value is adjusted to 9; then, the above-mentioned composite extractant and phenol-containing wastewater are subjected to four-stage countercurrent extraction in 4 separating funnels at a volume ratio of 1:4. Wherein mixed for 30 minutes, standing for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 380 mg/L and 7321 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 10477 mg/L and 17072 mg/L respectively. It can be calculated that 87.31% of unit phenols and 85.36% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

Example 7

90% methyl isobutyl ketone and 10% toluene are formulated into a compound extractant by volume ratio; the total phenol content is 10000mg/L, wherein the unit phenol content is 4000mg/L, and the polyphenol content is 6000mg/L The temperature of phenol-containing coal chemical wastewater is controlled at 50°C, and the pH value is adjusted to 9; then, the above-mentioned composite extractant and phenol-containing wastewater are subjected to four-stage countercurrent extraction in 4 separating funnels at a volume ratio of 1:4. Wherein mixed for 30 minutes, standing for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 199 mg/L and 473.4 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 15203 mg/L and 22106 mg/L respectively. It can be calculated that 95.02% of unit phenols and 92.11% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

Example 8

According to the volume ratio, 92% methyl isobutyl ketone and 8% toluene are formulated into a composite extractant; the total phenol content is 12000mg/L, wherein the unit phenol content is 5000mg/L, and the polyphenol content is 7000mg/L The temperature of phenol-containing coal chemical wastewater is controlled at 25°C, and the pH value is adjusted to 7; then, the above-mentioned composite extractant and phenol-containing wastewater are subjected to six-stage countercurrent extraction in 6 separating funnels at a volume ratio of 1:4. Wherein mixed for 30 minutes, standing for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 198 mg/L and 437 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 19208 mg/L and 26250 mg/L respectively. It can be calculated that 96.04% of unit phenols and 93.75% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

comparative example

Control the temperature of phenol-containing coal chemical wastewater with a total phenol content of 8000 mg/L, wherein the unit phenol content is 3000 mg/L, and the polyphenol content is 5000 mg/L at 25 ° C, and adjust the pH value to 7; then the above methyl Isobutyl ketone and phenol-containing wastewater were subjected to four-stage countercurrent extraction in four separatory funnels at a volume ratio of 1:4, where they were mixed for 30 minutes and allowed to stand for 15 minutes to obtain the extract phase and the raffinate phase.

The contents of unit phenols and polyphenols in the raffinate phase were detected to be 176 mg/L and 1090 mg/L respectively, and the contents of unit phenols and polyphenols in the extract phase were 11294 mg/L and 15642 mg/L respectively. It can be calculated that 94.12% of unit phenols and 78.21% of polyphenols in high-concentration phenol-containing wastewater can be removed by one extraction.

It can be seen from the results of the above examples that the extraction efficiency of polyphenols by the extractant can be greatly improved by using the composite extractant provided by the present invention. From the comparison of Example 1 and Example 7, it can be seen that when the pH value of the high-concentration phenol-containing wastewater was not higher than 7, the extractant could more significantly reduce the concentration of unit phenols and polyphenols in the phenol-containing wastewater. content. From the comparison of Example 1 and Comparative Example, it can be seen that the distribution coefficient of the composite extractant polyphenol is higher than that of methyl isobutyl ketone. It shows that the extraction effect of the composite extractant of the present invention on unit phenols is not inferior to that of methyl isobutyl ketone, and can greatly improve the extraction efficiency on polyphenols, which has great industrial application prospects.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. an extractant having a high partition coefficient to polyphenols in phenolic wastewater, is characterized in that: the extractant is composed of the main extractant methyl isobutyl ketone and the volume fraction of 90% to 95% by volume fraction % to 10% of the co-extractant toluene composition. 2. a method for extracting waste water containing phenol by using the extractant claimed in claim 1, is characterized in that comprising the steps: Methyl isobutyl ketone is used as the main extractant, and toluene is used as a synergistic extractant, wherein the volume fraction of methyl isobutyl ketone is 90% to 95%, and the volume fraction of toluene is 5% to 10%, and then the phenol-containing wastewater is compounded with this The extractant is subjected to multistage countercurrent extraction at a temperature of 25-70° C. to obtain an extract phase and a raffinate phase. 3. A method for extracting phenol-containing wastewater according to claim 2, characterized in that: said phenol-containing wastewater means that the polyphenol content is not less than 5000mg/L, and the total phenol content is 8000-18000mg/L L of high-concentration phenolic wastewater. 4. A method for extracting phenol-containing wastewater according to claim 2 or 3, characterized in that: the phenol-containing wastewater is phenol-containing coal chemical wastewater; polyphenols in the phenol-containing coal chemical wastewater The content is 5000-10000mg/L, and the unit phenol content is 3000-8000mg/L. 5. A method for extracting phenol-containing wastewater according to claim 2 or 3, characterized in that: the volume ratio of the composite extractant to phenol-containing wastewater is 1:(2～7). 6. A method for extracting phenol-containing wastewater according to claim 2 or 3, characterized in that: said extraction refers to the extraction under the condition of pH 6-9. 7. A method for extracting phenol-containing wastewater according to claim 6, characterized in that: said extraction refers to the extraction under the condition of pH 6-7. 8. A method for extracting phenol-containing wastewater according to claim 2 or 3, characterized in that: in the multistage countercurrent extraction process, the mixing time is 30 minutes, and the standing time is 15 minutes. 9. A method for extracting phenol-containing wastewater according to claim 2 or 3, characterized in that: before the composite extractant is used to extract the phenol-containing wastewater, it also includes degreasing and desuspension of the phenol-containing wastewater The process of pretreatment of substances, deacidification and deamination. 10. A method for extracting phenol-containing wastewater according to claim 2 or 3, characterized in that: after the composite extractant is used to extract the phenol-containing wastewater, the raffinate phase also enters into a solvent stripper for steaming After extracting and recovering the extractant, the clean water is sent to biochemical treatment; the extract phase enters the rectification tower to rectify and recover the crude phenol and extractant, and the recovered extractant is recycled.