Multi-component directional recovery method and device for furfural wastewater

Abstract

This invention relates to the field of furfural production wastewater treatment technology, and in particular to a method and apparatus for the targeted recovery of multi-component furfural wastewater. The recovery method includes: adsorbing furfural wastewater onto an adsorption resin, followed by gradient desorption treatment of the adsorption resin; the gradient desorption treatment sequentially includes first, second, and third gradient desorption treatments; performing the first gradient desorption treatment with a first eluent, which is an acidic alcohol-water solution with a conductivity of 590-1480 μS / cm; performing the second gradient desorption treatment with a second eluent, which is an alcohol-water solution with a mass fraction of 25%-65%; and performing the third gradient desorption treatment with a third eluent, which is an alkaline aqueous solution with a conductivity of 1100-3800 μS / cm or an aqueous solution with a mass fraction of not less than 70% organic solvent. This invention achieves the targeted separation of formic acid, acetic acid, and levulinic acid from furfural wastewater.

Description

Technical Field

[0001] This invention relates to the field of furfural production wastewater treatment technology, and in particular to a multi-component targeted recovery method and apparatus for furfural wastewater. Background Technology

[0002] Furfural is an important organic chemical raw material widely used in the synthesis of rubber, fibers, resins, petroleum processing, fragrances, dyes, and coatings. However, the production of furfural generates a large amount of process wastewater, characterized by high chemical oxygen demand (COD) and low pH. Direct discharge of this wastewater can severely damage aquatic ecosystems. Current conventional treatment methods often involve neutralization before treatment, but this wastewater contains formic acid, acetic acid, levulinic acid, and other chemicals with recovery value. The ineffective recycling of these substances by conventional processes leads to significant resource waste.

[0003] Chinese patent application CN109092212A discloses a single-bed, two-stage continuous system and method for the co-production of furfural and pulp and lignin, which employs distillation to separate furfural and acetic acid. Chinese patent application CN1050015A discloses a process for recovering acetic acid from organic industrial wastewater containing acetic acid, utilizing electrodialysis for separation and recovery. However, both distillation and electrodialysis processes suffer from high energy consumption and difficulty in achieving targeted recovery of multiple chemical components from wastewater.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for the multi-component targeted recovery of furfural wastewater.

[0006] To achieve the objectives of this invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for multi-component targeted recovery of furfural wastewater, comprising the following steps: Furfural wastewater was treated by adsorption with an adsorption resin, and then the adsorption resin was subjected to gradient desorption treatment. The gradient desorption process includes, in sequence, a first gradient desorption process, a second gradient desorption process, and a third gradient desorption process; The first gradient desorption treatment is performed using a first eluent, which is an acidic alcohol-water solution with a conductivity of 590~1480 μs / cm. The first gradient desorption treatment ends when the conductivity of the effluent first rises and then falls to a value ≤500 μs / cm lower than that of the inlet solution of the first gradient desorption treatment. The second gradient desorption process was performed using a second eluent, which was an alcohol-water solution with a mass fraction of 25% to 65%, and the endpoint of the second gradient desorption process was set at A ≤ threshold a. Where A = X is the refractive index of the second eluent, Y1 is the peak value of the refractive index of the effluent, and Y2 is the real-time refractive index of the effluent after the peak value of the refractive index appears. The third gradient desorption treatment is carried out using a third eluent, which is an alkaline aqueous solution with a conductivity of 1100~3800 μs / cm. The endpoint of the third gradient desorption treatment is defined as the point at which the conductivity of the effluent first rises and then falls to a value ≤500 μs / cm lower than that of the inlet solution of the third gradient desorption treatment. Alternatively, the third eluent may be an aqueous solution of an organic solvent with a mass fraction of not less than 70%, with B ≤ threshold b as the endpoint of the third gradient desorption treatment; Where B = N is the refractive index of the third eluent, M1 is the peak value of the refractive index of the effluent, and M2 is the real-time refractive index of the effluent after the peak value of the refractive index appears.

[0007] Furthermore, in the first eluent, the mass fraction of alcohol is 3% to 25%, preferably 5% to 20%.

[0008] Furthermore, in the first eluent, the alcohol includes at least one alcohol having 1 to 3 carbon atoms.

[0009] Furthermore, in the first eluent, the alcohol includes at least one of methanol, ethanol, and isopropanol.

[0010] Furthermore, the threshold a or the threshold b is each independently selected from 0 to 0.5.

[0011] Furthermore, the acidity adjuster in the acidic alcohol-water solution is an inorganic acid. Preferably, the inorganic acid includes at least one of hydrochloric acid and sulfuric acid.

[0012] Furthermore, the alcohol content in the second eluent is 30% to 60% by mass.

[0013] Furthermore, in the second eluent, the alcohol includes at least one alcohol having 1 to 3 carbon atoms.

[0014] Furthermore, in the second eluent, the alcohol includes at least one of methanol, ethanol, and isopropanol.

[0015] Furthermore, when the third eluent is an alkaline aqueous solution, the alkali in the third eluent includes at least one of sodium carbonate and sodium bicarbonate.

[0016] Furthermore, when the third eluent is an aqueous solution of an organic solvent, the mass fraction of the organic solvent in the third eluent is 70% to 90%.

[0017] Furthermore, the organic solvent in the third eluent includes alcohol.

[0018] Furthermore, in the third eluent, the alcohol includes at least one alcohol having 1 to 3 carbon atoms.

[0019] Furthermore, in the third eluent, the alcohol includes at least one of methanol, ethanol, and isopropanol.

[0020] Furthermore, the adsorption resin is a non-polar or weakly polar macroporous adsorption resin.

[0021] Furthermore, the adsorption resin includes at least one of HPD-100, HPD-300, H103, DM130, X-5 and AB-8 resins.

[0022] Furthermore, the furfural wastewater contains 0.4-2 wt% formic acid, 0.8-2.5 wt% acetic acid, and 0.3-1 wt% levulinic acid.

[0023] Furthermore, in the adsorption treatment, the adsorption treatment is stopped when the conductivity of the effluent first decreases and then increases to a value ≤1000μs / cm higher than that of the inlet liquid.

[0024] Furthermore, after the gradient desorption treatment, the adsorbent resin is further subjected to a regeneration treatment.

[0025] In a second aspect, the present invention provides an apparatus for implementing the multi-component targeted recovery method for furfural wastewater according to the first aspect, comprising: An adsorption-desorption unit includes at least one adsorption bed filled with adsorption resin. The inlet of the adsorption bed is connected to the wastewater pipeline, and the outlet of the adsorption bed is connected to the wastewater pipeline after adsorption. The inlet of the adsorption bed is also connected to the first eluent line, the second eluent line and the third eluent line respectively, and the outlet of the adsorption bed is also connected to the formic acid enrichment line, the acetic acid enrichment line and the levulinic acid enrichment line respectively. Furthermore, each of the above pipelines is equipped with a control valve; The detection unit includes a conductivity meter and a refractive index meter, both of which are located at the outlet of the adsorption bed and are used to detect the conductivity and refractive index of the effluent from the adsorption bed, respectively.

[0026] Furthermore, it also includes a control unit; the control valve is an electrically controlled valve; The control unit is electrically connected to the detection unit and each of the electrically controlled valves, and controls the opening and closing of each electrically controlled valve according to the feedback results from the detection unit.

[0027] Furthermore, the conductivity meter has a measurement range of 0~100000 μs / cm.

[0028] Furthermore, the refractive index detector has a measurement range of 1.3200~1.5000nD.

[0029] Furthermore, it also includes a regeneration unit, comprising a regenerated liquid storage tank and a regenerated effluent storage tank; the regenerated liquid storage tank is connected to the inlet of the adsorption bed, and the regenerated effluent storage tank is connected to the outlet of the adsorption bed.

[0030] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves the targeted separation of formic acid, acetic acid, and levulinic acid from furfural wastewater. Specifically, by employing an eluent with suitable elution strength and by monitoring the conductivity and / or refractive index of the effluent, formic acid, acetic acid, and levulinic acid (or their salts) are accurately and gradually recovered from furfural wastewater. The recovered formic acid and acetic acid can be used as catalysts in the furfural production process, reducing the amount of sulfuric acid catalyst required and thus lowering raw material costs. The levulinic acid salt can be further converted into high-value-added levulinic acid products. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 A schematic diagram of a device for multi-component targeted recovery of furfural wastewater provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another device for multi-component targeted recovery of furfural wastewater provided in an embodiment of the present invention.

[0033] Figure label: 10 - Adsorption bed; 20 - Conductivity meter; 30 - Refractive index meter. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0035] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] In a first aspect, the present invention provides a method for multi-component targeted recovery of furfural wastewater, comprising the following steps: Furfural wastewater was treated by adsorption with an adsorption resin, and then the adsorption resin was subjected to gradient desorption treatment. The gradient desorption process includes, in sequence, a first gradient desorption process, a second gradient desorption process, and a third gradient desorption process; The first gradient desorption treatment is performed using a first eluent, which is an acidic alcohol-water solution with a conductivity of 590~1480 μs / cm. The first gradient desorption treatment ends when the conductivity of the effluent first rises and then falls to a value ≤500 μs / cm lower than that of the inlet solution of the first gradient desorption treatment. The second gradient desorption process was performed using a second eluent, which was an alcohol-water solution with a mass fraction of 25% to 65%, and the endpoint of the second gradient desorption process was set at A ≤ threshold a. Where A = X is the refractive index of the second eluent, Y1 is the peak value of the refractive index of the effluent, and Y2 is the real-time refractive index of the effluent after the peak value of the refractive index appears. The third gradient desorption treatment is carried out using a third eluent, which is an alkaline aqueous solution with a conductivity of 1100~3800 μs / cm. The endpoint of the third gradient desorption treatment is defined as the point at which the conductivity of the effluent first rises and then falls to a value ≤500 μs / cm lower than that of the inlet solution of the third gradient desorption treatment. Alternatively, the third eluent may be an aqueous solution of an organic solvent with a mass fraction of not less than 70%, with B ≤ threshold b as the endpoint of the third gradient desorption treatment; Where B = N is the refractive index of the third eluent, M1 is the peak value of the refractive index of the effluent, and M2 is the real-time refractive index of the effluent after the peak value of the refractive index appears.

[0038] This invention achieves the targeted separation of formic acid, acetic acid, and levulinic acid from furfural wastewater. Specifically, by employing an eluent with suitable elution strength and monitoring the conductivity and / or refractive index of the effluent, formic acid, acetic acid, and levulinic acid (or their salts) are accurately and gradually recovered from furfural wastewater. The recovered formic acid and acetic acid can be used as catalysts in the furfural production process, reducing the amount of sulfuric acid catalyst required and thus lowering raw material costs; levulinic acid salts can be further converted into high-value-added levulinic acid products.

[0039] In some embodiments, the first eluent is an acidic alcohol-water solution with a conductivity of 590-1480 μs / cm. Specifically, the conductivity can be within the range of 590 μs / cm, 600 μs / cm, 700 μs / cm, 800 μs / cm, 900 μs / cm, 1000 μs / cm, 1100 μs / cm, 1200 μs / cm, 1350 μs / cm, 1480 μs / cm, or any combination thereof. The inventors created a suitable selective elution environment by adjusting the conductivity of the first eluent (acidic alcohol-water solution) to selectively elute formic acid. The inventors found that if the conductivity is too low, formic acid elution is incomplete, leading to a decrease in the purity of acetic acid obtained from the second elution process; if the conductivity is too high, the elution selectivity deteriorates, causing premature elution of acetic acid, resulting in low purity formic acid obtained from the first elution process.

[0040] The endpoint of the first-gradient desorption treatment is defined as the point at which the conductivity of the effluent first rises and then falls until the difference between the conductivity of the effluent and the conductivity of the inlet liquid in the first-gradient desorption treatment is ≤500 μs / cm. In practice, the conductivity of the effluent will first rise to a stable state, and then fall until the difference between the conductivity of the effluent and the conductivity of the inlet liquid in the first-gradient desorption treatment is ≤500 μs / cm, which is defined as the endpoint of the first-gradient desorption treatment.

[0041] Furthermore, this invention uses refractive index and employs formulas A and B to determine the endpoint when they are less than or equal to a certain threshold, providing a method for determining the endpoint using refractive index formulas and conditions, thus overcoming the current limitation of not being able to perform targeted recycling.

[0042] In some embodiments, the mass fraction of alcohol in the first eluent is 3% to 25%, specifically 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, or any combination thereof, preferably 5% to 20%. Controlling the mass fraction of alcohol in the first eluent within the above range helps to balance the amount of eluent used and the elution selectivity. When the mass fraction of alcohol in the first eluent is too low, the required amount of eluent is too large; when the mass fraction of alcohol in the first eluent is too high, acetic acid may elute prematurely, resulting in low formic acid purity.

[0043] In some embodiments, the alcohol in the first eluent includes at least one alcohol having 1 to 3 carbon atoms. Further, the alcohol in the first eluent includes at least one of methanol, ethanol, and isopropanol.

[0044] The objective of the first-gradient desorption process in this invention is to selectively elute formic acid. The inventors discovered that as the carbon number of the alcohol increases, some acetic acid and / or levulinic acid are desorbed. This may be because the hydrophobicity of the first eluent increases with the carbon number of the alcohol, leading to an increased risk of eluting acetic acid and levulinic acid. Therefore, alcohols with 1 to 3 carbon atoms are preferred to ensure product purity.

[0045] In some embodiments, the acidity adjuster in the acidic alcohol-water solution is an inorganic acid. Preferably, the inorganic acid includes at least one of hydrochloric acid and sulfuric acid. Conventional industrial-grade hydrochloric acid and sulfuric acid are sufficient.

[0046] Since the formic acid obtained from the first-gradient desorption treatment can be directly reused or concentrated and reused in the hydrolysis reactor in furfural production, and sulfuric acid is used as an acid conditioner, it is more conducive to the compatibility of subsequent applications.

[0047] In some embodiments, the second eluent is an alcohol-water solution with a mass fraction of 25% to 65%, wherein the mass fraction of alcohol can be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or any combination thereof, preferably 30% to 60%.

[0048] The effluent obtained through the second-gradient desorption process can be directly reused or concentrated and reused in the hydrolysis reactor of furfural production, or concentrated to remove the solvent to obtain industrial-grade acetic acid for downstream use. During the second-gradient desorption process, the inventors achieved targeted separation of the target substance by controlling the composition of the eluent. Experimental results show that if the alcohol content is too low, the target substance acetic acid is difficult to elute effectively; if the alcohol content is too high, it affects the selectivity of separation and recovery.

[0049] In some embodiments, the alcohol in the second eluent is selected with reference to the first eluent, that is, the alcohol includes at least one alcohol having 1 to 3 carbon atoms. Further, the alcohol in the second eluent includes at least one of methanol, ethanol, and isopropanol.

[0050] In some embodiments, the threshold 'a' is selected from 0 to 0.5, for example, any value or any combination of 0, 0.1, 0.2, 0.3, 0.4, and 0.5. The threshold can be chosen reasonably based on the elution conditions, such as the content of the substance to be recovered in the eluent. If the threshold is too large, the second gradient elution will be insufficient; if it is too small, a large amount of eluent will be used. Based on the above, those skilled in the art can select the threshold according to the recovery requirements; for example, a threshold of 0.5, 0.4, 0.3, 0.2, or 0.1 is within the scope of protection of this invention.

[0051] In some embodiments, when the third eluent is an alkaline aqueous solution, the conductivity of the third eluent is 1100~3800 μs / cm, specifically within the range of 1100 μs / cm, 1300 μs / cm, 1500 μs / cm, 1800 μs / cm, 2000 μs / cm, 2200 μs / cm, 2500 μs / cm, 2800 μs / cm, 3000 μs / cm, 3200 μs / cm, 3500 μs / cm, 3800 μs / cm, or any combination thereof. The inventors have found that if the conductivity of the alkaline aqueous solution of the third eluent is too high, it will damage the adsorption resin; therefore, the conductivity is limited to ≤3800 μs / cm. Conversely, if the conductivity is too low, a large amount of eluent is required. Therefore, the conductivity of the third eluent is selected to be 1100~3800 μs / cm.

[0052] The endpoint of the third-gradient desorption treatment is defined as the point at which the conductivity of the effluent first rises and then falls until the difference between the conductivity of the effluent and the conductivity of the inlet liquid in the third-gradient desorption treatment is ≤500 μs / cm. Generally, there is a steady state between the rise and fall, that is, the conductivity of the effluent will first rise to a steady state and then fall until the difference between the conductivity of the effluent and the conductivity of the inlet liquid in the third-gradient desorption treatment is ≤500 μs / cm.

[0053] In some embodiments, when the third eluent is an alkaline aqueous solution, the alkali in the third eluent includes at least one of sodium carbonate and sodium bicarbonate.

[0054] In some embodiments, when the third eluent is an aqueous solution of an organic solvent, the mass fraction of the organic solvent in the third eluent is not less than 70%, specifically it can be 70%, 75%, 80%, 85%, 90% or any combination thereof, such as 70%~90%.

[0055] In some embodiments, the organic solvent in the third eluent includes an alcohol. Further, the alcohol includes at least one alcohol having 1 to 3 carbon atoms. Even further, the alcohol includes at least one of methanol, ethanol, and isopropanol.

[0056] When the third eluent is an alkaline aqueous solution, the substance recovered is levulinate; when the third eluent is an aqueous solution of an organic solvent, the substance recovered is levulinic acid. If the amount of alkali or organic solvent in the third eluent is too low, the elution capacity for the target product levulinic acid will be insufficient.

[0057] In some embodiments, the threshold b is selected from 0 to 0.5, for example, any value or any combination of 0, 0.1, 0.2, 0.3, 0.4, and 0.5. The threshold can be chosen reasonably based on the elution conditions, such as the content of the substance to be recovered in the eluent. If the threshold is too large, it will lead to insufficient elution of the third gradient; if it is too small, a large amount of eluent will be used. Based on the above, those skilled in the art can select the threshold according to the recovery requirements; for example, a threshold b of 0.5, 0.4, 0.3, 0.2, or 0.1 is within the scope of protection of this invention.

[0058] In some embodiments, the adsorption resin is a nonpolar or weakly polar macroporous adsorption resin.

[0059] The method of selecting adsorption resin in this invention is such that the average pore size of the adsorption resin is larger than the kinetic diameter of the substance to be adsorbed, so that formic acid, acetic acid, and levulinic acid can all be effectively adsorbed. Therefore, this invention uses macroporous adsorption resin, which is a proprietary term with a clear technical definition in this field. In some embodiments of this invention, the resin grades used have pore sizes of 7-16 nm. Nonpolar and weakly polar are also proprietary terms with clear technical definitions in this field. Through experimental verification, the inventors found that the solution of this invention using polar resins is ineffective.

[0060] In some embodiments, the adsorbent resin includes at least one of HPD-100, HPD-300, H103, DM130, X-5, and AB-8 resins.

[0061] The inventors of this invention have discovered through research that by using the above-mentioned types of adsorption resins in conjunction with the gradient desorption process of this invention, the accuracy of separation and recovery of formic acid, acetic acid, and levulinic acid can be further improved.

[0062] In some embodiments, the formic acid content in the furfural wastewater is 0.4~2wt%, specifically 0.4wt%, 0.6wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, or any combination thereof; the acetic acid content is 0.8~2.5wt%, specifically 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.2wt%, 2.5wt%, or any combination thereof; and the levulinic acid content is 0.3~1wt%, specifically 0.3wt%, 0.5wt%, 0.6wt%, 0.8wt%, 1wt%, or any combination thereof.

[0063] In some embodiments, the conductivity of the furfural wastewater is 45,000 to 75,000 μS / cm.

[0064] In some implementations, furfural wastewater may be subjected to conventional sedimentation and / or filtration treatment as needed before adsorption treatment.

[0065] In some embodiments, during the adsorption treatment, the adsorption treatment is stopped when the conductivity of the effluent first decreases and then increases until the difference in conductivity between the effluent and the inlet liquid is ≤1000 μs / cm. During the adsorption treatment, the conductivity of the effluent is monitored in real time. The conductivity shows a trend of first decreasing and then increasing, with a steady state existing between the decrease and increase. That is, the conductivity of the effluent first decreases to a stable state and then increases until the difference in conductivity between the effluent and the inlet liquid is ≤1000 μs / cm, at which point the adsorption treatment is stopped.

[0066] In some embodiments, the adsorbent resin is further subjected to a regeneration treatment after the gradient desorption treatment.

[0067] In some embodiments, deionized water can be used to regenerate the adsorption resin. Further, the adsorption resin is rinsed with deionized water until the conductivity of the effluent is <10 μS / cm, at which point the regeneration process is complete.

[0068] Secondly, the present invention provides an apparatus for implementing the multi-component targeted recovery method for furfural wastewater according to the first aspect. Figure 1 A schematic diagram of an apparatus for multi-component targeted recovery of furfural wastewater provided in an embodiment of the present invention includes: An adsorption-desorption unit includes at least one adsorption bed 10, which is filled with adsorption resin. The inlet of the adsorption bed 10 is connected to the wastewater pipeline, and the outlet of the adsorption bed 10 is connected to the wastewater pipeline after adsorption. The inlet of the adsorption bed 10 is also connected to the first eluent line, the second eluent line and the third eluent line respectively, and the outlet of the adsorption bed 10 is also connected to the formic acid enrichment line, the acetic acid enrichment line and the levulinic acid enrichment line respectively. Furthermore, each of the above pipelines is equipped with a control valve; The detection unit includes a conductivity meter 20 and a refractive index meter 30. The conductivity meter 20 and the refractive index meter 30 are both located at the outlet of the adsorption bed 10 and are used to detect the conductivity and refractive index of the effluent from the adsorption bed 10, respectively.

[0069] Furthermore, it also includes a control unit; the control valve is an electrically controlled valve; The control unit is electrically connected to the detection unit and each of the electrically controlled valves, and controls the opening and closing of each electrically controlled valve according to the feedback results from the detection unit.

[0070] Furthermore, the conductivity meter 20 has a measurement range of 0~100000μs / cm.

[0071] Furthermore, the refractive index detector 30 has a measurement range of 1.3200~1.5000 nD.

[0072] Furthermore, it also includes a regeneration unit, comprising a regenerated liquid storage tank and a regenerated effluent storage tank; the regenerated liquid storage tank is connected to the inlet of the adsorption bed 10, and the regenerated effluent storage tank is connected to the outlet of the adsorption bed 10.

[0073] The regenerated liquid storage tank is connected to the inlet of the adsorption bed 10 via a deionized water pipeline, and the regenerated effluent storage tank is connected to the outlet of the adsorption bed 10 via a regenerated washing liquid pipeline.

[0074] Furthermore, the adsorption-desorption unit includes 2 to 5 adsorption beds 10. Figure 2 This is a schematic diagram of another device for multi-component targeted recovery of furfural wastewater provided in an embodiment of the present invention. Figure 2 As shown, exemplarily, there are three adsorption beds 10, configured in parallel. In actual operation, after one adsorption bed 10 completes the multi-component directional recovery of furfural wastewater, it immediately enters the regeneration treatment stage; to ensure the continuity of the recovery process, it can be switched to another adsorption bed 10 to continue the multi-component directional recovery operation of furfural wastewater.

[0075] In the specific embodiments described below, conductivity measurement was performed using an online conductivity meter (Mettler-Toledo M300 transmitter, equipped with an InPro 7100 four-electrode conductivity sensor, electrode constant K=1.0). The measurement temperature was controlled at 25.0±0.5℃, and the instrument had an automatic temperature compensation function (temperature compensation coefficient set to 2.0% / ℃). Calibration was performed using a standard KCl solution before measurement.

[0076] In the specific embodiments described below, the refractive index was measured using an online refractometer (Anton Paar L-Rix 510, measurement range 1.3200~1.5000 nD, resolution 0.0001 nD, accuracy ±0.0001 nD). The detection temperature was controlled at 25.0±0.1℃ by a built-in module, with automatic temperature compensation. Calibration was performed using deionized water and a standard refracting solution before use.

[0077] In the following specific examples, the contents of formic acid, acetic acid, and levulinic acid were all detected by liquid chromatography. Sample preparation: 1 g of the sample after solvent removal was added to 10 mL of 20 wt% ethanol aqueous solution and mixed to obtain the sample. Detection conditions included: chromatographic column: KC-811 ion exclusion column (300 mm × 8.0 mm ID); mobile phase: 0.1% (v / v) phosphoric acid aqueous solution, isocratic elution; flow rate: 0.8 mL / min; column temperature: 40℃; detector: ultraviolet detector, detection wavelength 210 nm; quantification method: external standard method was used for quantification, and the content of each component in the sample was calculated by peak area.

[0078] In the following specific examples, the content of sodium levulinate was detected by liquid chromatography. Sample pretreatment of levulinate: 1 g of the sample after solvent removal was added to 10 mL of 1 mol / L hydrochloric acid solution, shaken to mix, and allowed to stand at room temperature for 10 min. Then, an equal volume of 0.1% (v / v) phosphoric acid aqueous solution was added for dilution. The sample was filtered through a 0.45 μm filter membrane before injection. Detection conditions included: Column: C18 reversed-phase column; Mobile phase: acetonitrile-0.1% (v / v) phosphoric acid aqueous solution = 5:95 (volume ratio), isocratic elution; Flow rate: 1.0 mL / min; Column temperature: 30℃; Detector: UV detector, detection wavelength 210 nm; Quantification method: External standard method was used. The content of levulinic acid was measured and then converted to the content of sodium levulinate (conversion factor: sodium levulinate content = levulinic acid content × 1.196).

[0079] Example 1 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of the furfural wastewater to be treated was analyzed, in which the content of formic acid was 0.8wt%, the content of acetic acid was 1.8wt%, the content of levulinic acid was 0.6wt%, and the conductivity was 62533μs / cm.

[0080] (2) The furfural wastewater obtained in step (1) was passed through the adsorption column at a flow rate of 2.0 BV / h. The conductivity of the effluent was monitored in real time, showing a trend of first decreasing and then increasing. When the conductivity of the effluent first decreased to a stable state and then increased to a value of 500 μs / cm compared with the conductivity of the inlet liquid, the adsorption treatment was stopped. The wastewater treatment volume was 5 BV. The adsorption column was filled with HPD-300 adsorption resin, and the resin packing volume (BV) was 0.4 m³. 3 .

[0081] (3) The first eluent was introduced into the adsorption column treated in step (2) at a flow rate of 1 BV / h for the first elution treatment. The conductivity of the effluent was monitored in real time and the effluent was collected. The conductivity showed a trend of first rising and then falling. When the conductivity of the effluent first rose to a stable state and then fell to a difference of 500 μs / cm with the conductivity of the inlet liquid of the first elution treatment, the first elution treatment was stopped. The first elution treatment volume was 0.9 BV. The first eluent was a 10% ethanol aqueous solution, and the conductivity was adjusted to 792 μs / cm with sulfuric acid. The collected effluent of the first elution treatment was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 96.5 wt%, the content of acetic acid was 2.8 wt%, and the content of levulinic acid was 0.5 wt%.

[0082] (4) The second eluent was passed into the adsorption column treated in step (3) at a flow rate of 1 BV / h for the second elution treatment. The second eluent was an isopropanol aqueous solution with a mass fraction of 40% and a refractive index X = 1.358 Nd. The refractive index of the effluent was monitored in real time and the effluent was collected. The refractive index showed a trend of first rising and then falling. The refractive index of the effluent first rose to the peak refractive index (peak refractive index Y1 = 1.369 Nd), and then the refractive index showed an inflection point and decreased. When the real-time refractive index Y2 dropped to Y2 = 1.360 Nd, A = 0.182, and the second elution treatment was stopped. The second elution treatment volume was 1 BV. The collected effluent from the second elution treatment was subjected to solvent removal treatment. The composition of the liquid after solvent removal was analyzed. The content of formic acid was 0.3 wt%, the content of acetic acid was 98.5 wt%, and the content of levulinic acid was 0.8 wt%.

[0083] (5) The third eluent was introduced into the adsorption column treated in step (4) at a flow rate of 1 BV / h for the third elution treatment. The conductivity of the effluent was monitored in real time and the effluent was collected. The conductivity showed a trend of first rising and then falling. When the conductivity of the effluent first rose to a stable state and then fell to a difference of 300 μs / cm between the conductivity of the effluent and the conductivity of the inlet liquid of the third elution treatment, the third elution treatment was stopped. The third elution treatment volume was 0.8 BV. The third eluent was an aqueous sodium carbonate solution with a conductivity of 2000 μs / cm. The collected effluent from the third elution treatment was solvent removed to obtain sodium levulinate solid with a purity of 97.6 wt%.

[0084] (6) Pass deionized water into the adsorption column treated in step (5) at a flow rate of 4 BV / h for rinsing and regeneration. Detect the conductivity of the effluent. When the conductivity of the effluent is <10 μs / cm, the regeneration ends and the next round of adsorption and elution can be carried out.

[0085] Example 2 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of the furfural wastewater to be treated was analyzed, in which the content of formic acid was 0.4wt%, the content of acetic acid was 2.1wt%, the content of levulinic acid was 0.5wt%, and the conductivity was 55261μs / cm.

[0086] (2) The furfural wastewater obtained in step (1) was passed through the adsorption column at a flow rate of 2.0 BV / h. The conductivity of the effluent was monitored in real time, showing a trend of first decreasing and then increasing. When the conductivity of the effluent first decreased to a stable state and then increased to a value of 300 μs / cm higher than that of the inlet liquid, the adsorption treatment was stopped. The wastewater treatment volume was 5.2 BV. The adsorption column was filled with AB-8 adsorption resin, and the resin packing volume (BV) was 0.4 m³.3 .

[0087] (3) The first eluent was introduced into the adsorption column treated in step (2) at a flow rate of 1 BV / h for the first elution treatment. The conductivity of the effluent was monitored in real time and the effluent was collected. The conductivity showed a trend of first rising and then falling. When the conductivity of the effluent first rose to a stable state and then fell to a difference of 300 μs / cm between the conductivity of the effluent and the conductivity of the inlet liquid of the first elution treatment, the first elution treatment was stopped. The first elution treatment volume was 1.2 BV. The first eluent was a methanol aqueous solution with a mass fraction of 5%, and the conductivity was adjusted to 1320 μs / cm by hydrochloric acid. The collected effluent of the first elution treatment was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 95.9 wt%, the content of acetic acid was 2.6 wt%, and the content of levulinic acid was 0.9 wt%.

[0088] (4) The second eluent was passed into the adsorption column treated in step (3) at a flow rate of 1 BV / h for the second elution treatment. The second eluent was a 30% ethanol aqueous solution with a refractive index X = 1.345 Nd. The refractive index of the effluent was monitored in real time and the effluent was collected. The refractive index showed a trend of first rising and then falling. The refractive index of the effluent first rose to the peak refractive index (peak refractive index Y1 = 1.358 Nd), and then the refractive index showed an inflection point and decreased. When the real-time refractive index Y2 dropped to Y2 = 1.347 Nd, A = 0.154, and the second elution treatment was stopped. The amount of the second elution treatment was 1.2 BV. The collected effluent from the second elution treatment was subjected to solvent removal treatment. The composition of the liquid after solvent removal was analyzed. The content of formic acid was 0.2 wt%, the content of acetic acid was 98.7 wt%, and the content of levulinic acid was 0.6 wt%.

[0089] (5) The third eluent was introduced into the adsorption column treated in step (4) at a flow rate of 1 BV / h for the third elution treatment. The conductivity of the effluent was monitored in real time and the effluent was collected. The conductivity showed a trend of first rising and then falling. When the conductivity of the effluent first rose to a stable state and then fell to a value of 500 μs / cm lower than that of the inlet liquid of the third elution treatment, the third elution treatment was stopped. The third elution treatment volume was 0.7 BV. The third eluent was an aqueous sodium carbonate solution with a conductivity of 3800 μs / cm. The collected effluent from the third elution treatment was solvent removed to obtain sodium levulinate solid with a purity of 97.6 wt%.

[0090] (6) Pass deionized water into the adsorption column treated in step (5) at a flow rate of 4 BV / h for rinsing and regeneration. Detect the conductivity of the effluent. When the conductivity of the effluent is <10 μs / cm, the regeneration ends and the next round of adsorption and elution can be carried out.

[0091] Example 3 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of the furfural wastewater to be treated was analyzed, in which the content of formic acid was 0.8wt%, the content of acetic acid was 1.8wt%, the content of levulinic acid was 0.6wt%, and the conductivity was 62533μs / cm.

[0092] (2) The furfural wastewater obtained in step (1) was passed through the adsorption column at a flow rate of 2.0 BV / h. The conductivity of the effluent was monitored in real time, showing a trend of first decreasing and then increasing. When the conductivity of the effluent first decreased to a stable state and then increased to a value of 1000 μs / cm compared with the conductivity of the inlet liquid, the adsorption treatment was stopped. The wastewater treatment volume was 5.1 BV. The adsorption column was filled with DM-130 adsorption resin, and the resin packing volume (BV) was 0.4 m³. 3 .

[0093] (3) The first eluent was introduced into the adsorption column treated in step (2) at a flow rate of 1 BV / h for the first elution treatment. The conductivity of the effluent was monitored in real time and the effluent was collected. The conductivity showed a trend of first rising and then falling. When the conductivity of the effluent first rose to a stable state and then fell to a value of 100 μs / cm with the conductivity of the inlet liquid of the first elution treatment, the first elution treatment was stopped. The first elution treatment volume was 1.1 BV. The first eluent was an aqueous solution of ethanol with a mass fraction of 15%, and the conductivity was adjusted to 745 μs / cm with hydrochloric acid. The collected effluent of the first elution treatment was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 96.0 wt%, the content of acetic acid was 3.4 wt%, and the content of levulinic acid was 0.4 wt%.

[0094] (4) The second eluent was passed into the adsorption column treated in step (3) at a flow rate of 1 BV / h for the second elution treatment. The second eluent was an isopropanol aqueous solution with a mass fraction of 40% and a refractive index X = 1.358 Nd. The refractive index of the effluent was monitored in real time and the effluent was collected. The refractive index showed a trend of first rising and then falling. The refractive index of the effluent first rose to the peak refractive index (peak refractive index Y1 = 1.371 Nd), and then the refractive index showed an inflection point and decreased. When the real-time refractive index Y2 dropped to Y2 = 1.361 Nd, A = 0.231, and the second elution treatment was stopped. The amount of the second elution treatment was 1.0 BV. The collected effluent from the second elution treatment was subjected to solvent removal treatment. The composition of the liquid after solvent removal was analyzed. The content of formic acid was 0.4 wt%, the content of acetic acid was 98.2 wt%, and the content of levulinic acid was 0.9 wt%.

[0095] (5) The third eluent was introduced into the adsorption column treated in step (4) at a flow rate of 1 BV / h for the third elution treatment. The conductivity of the effluent was monitored in real time and the effluent was collected. The conductivity showed a trend of first rising and then falling. When the conductivity of the effluent first rose to a stable state and then fell to a difference of 300 μs / cm between the conductivity of the effluent and the conductivity of the inlet liquid of the third elution treatment, the third elution treatment was stopped. The third elution treatment volume was 0.9 BV. The third eluent was an aqueous solution of sodium bicarbonate with a conductivity of 1100 μs / cm. The collected effluent of the third elution treatment was subjected to solvent removal to obtain sodium levulinate solid with a purity of 97.5 wt%.

[0096] (6) Pass deionized water into the adsorption column treated in step (5) at a flow rate of 4 BV / h for rinsing and regeneration. Detect the conductivity of the effluent. When the conductivity of the effluent is <10 μs / cm, the regeneration ends and the next round of adsorption and elution can be carried out.

[0097] Example 4 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of the furfural wastewater to be treated was analyzed, in which the content of formic acid was 1.1wt%, the content of acetic acid was 2.5wt%, the content of levulinic acid was 0.8wt%, and the conductivity was 74215μs / cm.

[0098] (2) The furfural wastewater obtained in step (1) was passed through the adsorption column at a flow rate of 2.0 BV / h. The conductivity of the effluent was monitored in real time, showing a trend of first decreasing and then increasing. When the conductivity of the effluent first decreased to a stable state and then increased to a difference of 600 μs / cm between the conductivity of the effluent and the inlet liquid, the adsorption treatment was stopped. The wastewater treatment volume was 3.4 BV. The adsorption column was filled with DM-130 adsorption resin, and the resin packing volume (BV) was 0.4 m³. 3 .

[0099] (3) The first eluent was introduced into the adsorption column treated in step (2) at a flow rate of 1 BV / h for the first elution treatment. The conductivity of the effluent was monitored in real time and the effluent was collected. The conductivity showed a trend of first rising and then falling. When the conductivity of the effluent first rose to a stable state and then fell to a difference of 300 μs / cm between the conductivity of the effluent and the conductivity of the inlet liquid of the first elution treatment, the first elution treatment was stopped. The first elution treatment volume was 0.8 BV. The first eluent was an isopropanol aqueous solution with a mass fraction of 20%, and the conductivity was adjusted to 800 μs / cm with sulfuric acid. The collected effluent of the first elution treatment was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 92.9 wt%, the content of acetic acid was 5.2 wt%, and the content of levulinic acid was 1.5 wt%.

[0100] (4) The second eluent was passed into the adsorption column treated in step (3) at a flow rate of 1 BV / h for the second elution treatment. The second eluent was an isopropanol aqueous solution with a mass fraction of 60% and a refractive index X = 1.370 Nd. The refractive index of the effluent was monitored in real time and the effluent was collected. The refractive index showed a trend of first rising and then falling. The refractive index of the effluent first rose to the peak refractive index (peak refractive index Y1 = 1.382 Nd), and then the refractive index showed an inflection point and decreased. When the real-time refractive index Y2 decreased to Y2 = 1.371 Nd, A = 0.083, and the second elution treatment was stopped. The amount of the second elution treatment was 0.9 BV. The collected effluent from the second elution treatment was subjected to solvent removal treatment. The composition of the liquid after solvent removal was analyzed. The content of formic acid was 0.5 wt%, the content of acetic acid was 97.6 wt%, and the content of levulinic acid was 1.5 wt%.

[0101] (5) The third eluent was passed into the adsorption column treated in step (4) at a flow rate of 1 BV / h for the third elution treatment. The refractive index of the effluent was monitored in real time and the effluent was collected. The refractive index first rose to the peak refractive index (peak refractive index M1 = 1.351 Nd), and then the refractive index showed an inflection point and decreased. When the real-time refractive index M2 decreased to M2 = 1.329 Nd, B = 0.043, and the third elution treatment was stopped. The third elution treatment volume was 1.0 BV. The third eluent was a methanol aqueous solution with a mass fraction of 70% and a refractive index N = 1.328. The collected effluent from the third elution treatment was subjected to solvent removal to obtain solid levulinic acid with a purity of 98.3 wt%.

[0102] (6) Pass deionized water into the adsorption column treated in step (5) at a flow rate of 4 BV / h for rinsing and regeneration. Detect the conductivity of the effluent. When the conductivity of the effluent is <10 μs / cm, the regeneration ends and the next round of adsorption and elution can be carried out.

[0103] Example 5 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0104] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0105] (3) The difference between the first elution in step (3) and that in Example 1 is that the first eluent is a 3% (w / w) aqueous ethanol solution, and the conductivity is adjusted to 792 μs / cm using sulfuric acid. The remaining control methods are the same as in Example 1, and the first elution volume is 2.3 BV. The collected effluent from the first elution was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 96.2 wt%, the content of acetic acid was 2.4 wt%, and the content of levulinic acid was 0.7 wt%.

[0106] (4) The eluent and control method for the second elution in step (4) are the same as in Example 1, and the second elution volume is 1.1 BV. The collected effluent from the second elution is subjected to solvent removal treatment, and the composition of the liquid after solvent removal is analyzed. The content of formic acid is 2.9 wt%, the content of acetic acid is 94.9 wt%, and the content of levulinic acid is 2.1 wt%.

[0107] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.8 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 97.3 wt%.

[0108] (6) The regeneration process in step (6) is the same as in Example 1.

[0109] Example 6 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0110] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0111] (3) The difference between the first elution in step (3) and that in Example 1 is that the first eluent is a 25% (w / w) aqueous ethanol solution, and the conductivity is adjusted to 792 μS / cm using sulfuric acid. The remaining control methods are the same as in Example 1, and the first elution volume is 0.7 BV. The collected effluent from the first elution was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 88.1 wt%, the content of acetic acid was 9.9 wt%, and the content of levulinic acid was 1.8 wt%.

[0112] (4) The eluent and control method for the second elution in step (4) are the same as in Example 1, and the second elution volume is 0.9 BV. The collected effluent from the second elution process is subjected to solvent removal treatment, and the composition of the liquid after solvent removal is analyzed. The content of formic acid is 1.1 wt%, the content of acetic acid is 96.8 wt%, and the content of levulinic acid is 1.9 wt%.

[0113] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.8 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 97.8 wt%.

[0114] (6) The regeneration process in step (6) is the same as in Example 1.

[0115] Example 7 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0116] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0117] (3) The difference between the first elution in step (3) and that in Example 1 is that the first eluent is a 10% butanol aqueous solution, and the conductivity is adjusted to 792 μS / cm using sulfuric acid. The remaining control methods are the same as in Example 1, and the first elution volume is 0.6 BV. The collected effluent from the first elution was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 70.3 wt%, the content of acetic acid was 24.6 wt%, and the content of levulinic acid was 4.9 wt%.

[0118] (4) The eluent and control method for the second elution in step (4) are the same as in Example 1, and the second elution volume is 1.1 BV. The collected effluent from the second elution is subjected to solvent removal treatment, and the composition of the liquid after solvent removal is analyzed. The content of formic acid is 8.8 wt%, the content of acetic acid is 89.8 wt%, and the content of levulinic acid is 0.9 wt%.

[0119] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.9 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 94.0 wt%.

[0120] (6) The regeneration process in step (6) is the same as in Example 1.

[0121] Example 8 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0122] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0123] (3) The eluent and control method for the first elution in step (3) are the same as in Example 1.

[0124] (4) The difference between the second elution in step (4) and that in Example 1 is that the second eluent is a 25% isopropanol aqueous solution (refractive index X = 1.355 Nd), and the other control methods are the same as in Example 1. The second elution volume is 1.8 BV. The collected effluent from the second elution was subjected to solvent removal treatment, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 0.5 wt%, the content of acetic acid was 98.3 wt%, and the content of levulinic acid was 0.7 wt%.

[0125] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.9 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 96.8 wt%.

[0126] (6) The regeneration process in step (6) is the same as in Example 1.

[0127] Example 9 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0128] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0129] (3) The eluent and control method for the first elution in step (3) are the same as in Example 1.

[0130] (4) The difference between the second elution in step (4) and that in Example 1 is that the second eluent is a 65% isopropanol aqueous solution (refractive index X = 1.373 Nd), and the other control methods are the same as in Example 1. The second elution volume is 0.8 BV. The collected effluent from the second elution was subjected to solvent removal treatment, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 0.3 wt%, the content of acetic acid was 95.0 wt%, and the content of levulinic acid was 4.6 wt%.

[0131] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.8 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 97.2 wt%.

[0132] (6) The regeneration process in step (6) is the same as in Example 1.

[0133] Example 10 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0134] (2) The difference between the adsorption treatment in step (2) and Example 1 is that the adsorption column in this example is filled with NKA-9 adsorption resin.

[0135] (3) The eluent and control method for the first elution in step (3) are the same as in Example 1, and the first elution volume is 1.5 BV. The collected effluent from the first elution was solvent removed, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 80.3 wt%, the content of acetic acid was 14.8 wt%, and the content of levulinic acid was 4.8 wt%.

[0136] (4) The eluent and control method for the second elution in step (4) are the same as in Example 1, and the second elution volume is 1.8 BV. The collected effluent from the second elution is subjected to solvent removal treatment, and the composition of the liquid after solvent removal is analyzed. The content of formic acid is 10.1 wt%, the content of acetic acid is 84.8 wt%, and the content of levulinic acid is 4.7 wt%.

[0137] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 1 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 85.4 wt%.

[0138] (6) The regeneration process in step (6) is the same as in Example 1.

[0139] Example 11 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0140] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0141] (3) The difference between the first elution step (3) and Example 1 is that sulfuric acid was used to adjust the conductivity to 1480 μS / cm. The remaining control methods are the same as in Example 1, and the first elution volume is 1.2 BV. The collected effluent from the first elution was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 92.3 wt%, the content of acetic acid was 6.1 wt%, and the content of levulinic acid was 1.2 wt%.

[0142] (4) The eluent and control method for the second elution in step (4) are the same as in Example 1, and the second elution volume is 1.1 BV. The collected effluent from the second elution is subjected to solvent removal treatment, and the composition of the liquid after solvent removal is analyzed. The content of formic acid is 1.6 wt%, the content of acetic acid is 95.5 wt%, and the content of levulinic acid is 2.5 wt%.

[0143] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.8 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 97.4 wt%.

[0144] (6) The regeneration process in step (6) is the same as in Example 1.

[0145] Example 12 This embodiment provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0146] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0147] (3) The difference between the first elution step (3) and Example 1 is that sulfuric acid was used to adjust the conductivity to 590 μs / cm. The remaining control methods are the same as in Example 1, and the first elution volume is 0.8 BV. The collected effluent from the first elution was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 94.8 wt%, the content of acetic acid was 3.9 wt%, and the content of levulinic acid was 0.9 wt%.

[0148] (4) The eluent and control method for the second elution in step (4) are the same as in Example 1, and the second elution volume is 1.2 BV. The collected effluent from the second elution is subjected to solvent removal treatment, and the composition of the liquid after solvent removal is analyzed. The content of formic acid is 3.9 wt%, the content of acetic acid is 94.8 wt%, and the content of levulinic acid is 0.8 wt%.

[0149] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.9 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 96.4 wt%.

[0150] (6) The regeneration process in step (6) is the same as in Example 1.

[0151] Comparative Example 1 Comparative Example 1 provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0152] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0153] (3) The difference between the first elution step (3) and Example 1 is that sulfuric acid was used to adjust the conductivity to 1600 μs / cm. The remaining control methods are the same as in Example 1, and the first elution volume is 1.4 BV. The collected effluent from the first elution was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 86.1 wt%, the content of acetic acid was 12.1 wt%, and the content of levulinic acid was 1.6 wt%.

[0154] (4) The eluent and control method for the second elution in step (4) are the same as in Example 1, and the second elution volume is 1.2 BV. The collected effluent from the second elution is subjected to solvent removal treatment, and the composition of the liquid after solvent removal is analyzed. The content of formic acid is 2.8 wt%, the content of acetic acid is 94.7 wt%, and the content of levulinic acid is 2.1 wt%.

[0155] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.8 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 97.7 wt%.

[0156] (6) The regeneration process in step (6) is the same as in Example 1.

[0157] Comparative Example 2 Comparative Example 2 provides a multi-component targeted recovery method for furfural wastewater, as detailed below: (1) The composition of furfural wastewater in step (1) is the same as that in Example 1.

[0158] (2) The adsorption treatment in step (2) is the same as in Example 1.

[0159] (3) The difference between the first elution step (3) and Example 1 is that sulfuric acid was used to adjust the conductivity to 500 μs / cm. The remaining control methods are the same as in Example 1, and the first elution volume is 0.7 BV. The collected effluent from the first elution was subjected to solvent removal, and the composition of the liquid after solvent removal was analyzed. The content of formic acid was 89.5 wt%, the content of acetic acid was 8.9 wt%, and the content of levulinic acid was 1.3 wt%.

[0160] (4) The eluent and control method for the second elution in step (4) are the same as in Example 1, and the second elution volume is 1.3 BV. The collected effluent from the second elution is subjected to solvent removal treatment, and the composition of the liquid after solvent removal is analyzed. The content of formic acid is 5.2 wt%, the content of acetic acid is 90.7 wt%, and the content of levulinic acid is 0.7 wt%.

[0161] (5) The eluent and control method for the third elution in step (5) are the same as in Example 1, and the third elution volume is 0.7 BV. The collected effluent from the third elution is solvent removed to obtain sodium levulinate solid with a purity of 96.3 wt%.

[0162] (6) The regeneration process in step (6) is the same as in Example 1.

[0163] This invention achieves the targeted separation of formic acid, acetic acid, and levulinic acid from furfural wastewater. Specifically, by employing an eluent with suitable elution strength and by monitoring the conductivity and / or refractive index of the effluent, formic acid, acetic acid, and levulinic acid (or their salts) are accurately and gradually recovered from furfural wastewater. The recovered formic acid and acetic acid can be used as catalysts in the furfural production process, reducing the amount of sulfuric acid catalyst required and thus lowering raw material costs. The levulinic acid salt can be further converted into high-value-added levulinic acid products.

[0164] Specifically, based on the experimental results of Examples 1, 11-12, and Comparative Examples 1-2, it is evident that using an acidic alcohol-water solution with suitable conductivity as the first eluent is beneficial for the selective elution of formic acid. Experimental data show that if the conductivity of the first eluent is too low, formic acid elution is incomplete, the yield decreases, and the purity of the acetic acid obtained from the second elution process decreases. Conversely, if the conductivity of the first eluent is too high, the elution selectivity deteriorates, acetic acid elutes prematurely, resulting in low purity formic acid obtained from the first elution process.

[0165] According to the experimental results of Examples 1 and 5-6, when the mass fraction of alcohol in the first eluent decreases, the amount of eluent used increases; when the mass fraction of alcohol in the first eluent increases, acetic acid will elute prematurely, resulting in low purity of formic acid obtained from the first elution treatment.

[0166] According to the experimental results of Examples 1 and 7, when the number of carbon atoms in the alcohol in the first eluent increases to 4, the selectivity deteriorates, and some acetic acid and levulinic acid are desorbed, resulting in low purity of formic acid obtained from the first elution treatment.

[0167] According to the experimental results of Examples 1 and 8-9, when the mass fraction of alcohol in the second eluent decreases, the target substance acetic acid is difficult to be effectively eluted, and the amount of eluent used increases; when the mass fraction of alcohol in the second eluent increases, levulinic acid will be eluted prematurely, resulting in low purity of acetic acid obtained from the second elution treatment.

[0168] According to the experimental results of Examples 1 and 10, when a polar adsorption resin is used, not only is the adsorption performance of formic acid, acetic acid and levulinic acid poor, but the separation effect is also poor, resulting in a low product yield.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the multi-component targeted recovery of furfural waste water, characterized in that, Includes the following steps: Furfural wastewater was treated by adsorption with an adsorption resin, and then the adsorption resin was subjected to gradient desorption treatment. The gradient desorption process includes, in sequence, a first gradient desorption process, a second gradient desorption process, and a third gradient desorption process; The first gradient desorption treatment is performed using a first eluent, which is an acidic alcohol-water solution with a conductivity of 590~1480 μs / cm. The first gradient desorption treatment ends when the conductivity of the effluent first rises and then falls to a value ≤500 μs / cm lower than that of the inlet solution of the first gradient desorption treatment. The second gradient desorption process was performed using a second eluent, which was an alcohol-water solution with a mass fraction of 25% to 65%, and the endpoint of the second gradient desorption process was set at A ≤ threshold a. Where A = X is the refractive index of the second eluent, Y1 is the peak value of the refractive index of the effluent, and Y2 is the real-time refractive index of the effluent after the peak value of the refractive index appears. The third gradient desorption treatment is carried out using a third eluent, which is an alkaline aqueous solution with a conductivity of 1100~3800 μs / cm. The endpoint of the third gradient desorption treatment is defined as the point at which the conductivity of the effluent first rises and then falls to a value ≤500 μs / cm lower than that of the inlet solution of the third gradient desorption treatment. Alternatively, the third eluent may be an aqueous solution of an organic solvent with a mass fraction of not less than 70%, with B ≤ threshold b as the endpoint of the third gradient desorption treatment; Where B = N is the refractive index of the third eluent, M1 is the peak value of the refractive index of the effluent, and M2 is the real-time refractive index of the effluent after the peak value of the refractive index appears.

2. The multi-component targeted recovery method for furfural wastewater according to claim 1, characterized in that, In the first eluent, the mass fraction of alcohol is 3%~25%; Preferably, the alcohol in the first eluent has a mass fraction of 5% to 20%; Preferably, the alcohol in the first eluent includes at least one alcohol having 1 to 3 carbon atoms; Preferably, the threshold a or the threshold b is independently selected from 0 to 0.5; Preferably, the alcohol in the first eluent includes at least one of methanol, ethanol, and isopropanol; Preferably, the acidity adjuster in the acidic alcohol-water solution is an inorganic acid; preferably, the inorganic acid includes at least one of hydrochloric acid and sulfuric acid.

3. The multi-component targeted recovery method for furfural wastewater according to claim 1, characterized in that, In the second eluent, the mass fraction of alcohol is 30%~60%; Preferably, in the second eluent, the alcohol includes at least one alcohol having 1 to 3 carbon atoms; Preferably, the alcohol in the second eluent includes at least one of methanol, ethanol, and isopropanol.

4. The multi-component targeted recovery method for furfural wastewater according to claim 1, characterized in that, When the third eluent is an alkaline aqueous solution, the alkali in the third eluent includes at least one of sodium carbonate and sodium bicarbonate; When the third eluent is an aqueous solution of an organic solvent, the mass fraction of the organic solvent in the third eluent is 70% to 90%. Preferably, the organic solvent in the third eluent includes alcohol; Preferably, in the third eluent, the alcohol includes at least one alcohol having 1 to 3 carbon atoms; Preferably, the alcohol in the third eluent includes at least one of methanol, ethanol, and isopropanol.

5. The multi-component targeted recovery method for furfural wastewater according to claim 1, characterized in that, The adsorption resin is a non-polar or weakly polar macroporous adsorption resin. Preferably, the adsorbent resin includes at least one of HPD-100, HPD-300, H103, DM130, X-5 and AB-8 resins.

6. The multi-component targeted recovery method for furfural wastewater according to claim 1, characterized in that, The furfural wastewater contains 0.4-2 wt% formic acid, 0.8-2.5 wt% acetic acid, and 0.3-1 wt% levulinic acid. Preferably, in the adsorption treatment, the adsorption treatment is stopped when the conductivity of the effluent first decreases and then increases to a value ≤1000 μs / cm higher than that of the inlet liquid. Preferably, after the gradient desorption treatment, the adsorbent resin is further subjected to a regeneration treatment.

7. An apparatus for implementing the multi-component targeted recovery method for furfural wastewater according to any one of claims 1 to 6, characterized in that, include: An adsorption-desorption unit includes at least one adsorption bed filled with adsorption resin. The inlet of the adsorption bed is connected to the wastewater pipeline, and the outlet of the adsorption bed is connected to the wastewater pipeline after adsorption. The inlet of the adsorption bed is also connected to the first eluent line, the second eluent line and the third eluent line respectively, and the outlet of the adsorption bed is also connected to the formic acid enrichment line, the acetic acid enrichment line and the levulinic acid enrichment line respectively. Furthermore, each of the above pipelines is equipped with a control valve; The detection unit includes a conductivity meter and a refractive index meter, both of which are located at the outlet of the adsorption bed and are used to detect the conductivity and refractive index of the effluent from the adsorption bed, respectively.

8. The apparatus according to claim 7, characterized in that, It also includes a control unit; The control valve is an electrically controlled valve; The control unit is electrically connected to the detection unit and each of the electrically controlled valves, and controls the opening and closing of each electrically controlled valve according to the feedback results from the detection unit.

9. The apparatus according to claim 7, characterized in that, The detection unit has at least one of the following characteristics: (1) The conductivity meter has a range of 0~100000μs / cm; (2) The refractive index detector has a measurement range of 1.3200~1.5000nD.

10. The apparatus according to claim 7, characterized in that, It also includes a regeneration unit, comprising a regenerated liquid storage tank and a regenerated effluent storage tank; the regenerated liquid storage tank is connected to the inlet of the adsorption bed, and the regenerated effluent storage tank is connected to the outlet of the adsorption bed.

Images