Method for separating cotton stalk lignin and byproduct furfural by using eutectic solvent-methyl isobutyl ketone two-phase solvent

Abstract

The invention discloses a method for separating cotton stalk lignin and byproduct furfural by using a deep-eutectic solvent-methyl isobutyl ketone double-phase solvent. The method comprises the following steps: step 1, preparing a deep-eutectic solvent; 2, the cotton stalks are treated through a deep eutectic solvent-methyl isobutyl ketone two-phase solvent; and step 3, separating lignin and furfural. Compared with traditional lignin extraction, the method has the advantages that the eutectic solvent has higher destructive power on hydrogen bonds among lignin, cellulose and hemicellulose, and the extraction efficiency of the lignin is improved; by adding methyl isobutyl ketone, the byproduct furfural of the hemicellulose treated by the eutectic solvent can be recovered, and the biomass utilization rate is increased; the raw materials are simple and easy to obtain, the cost is low, the eutectic solvent and the methyl isobutyl ketone can be recycled through rotary evaporation, and the green development requirement is met.

Description

TECHNICAL FIELD

[0001] The application relates to a method for separating cotton stalk lignin and byproduct furfural by using a deep eutectic solvent-methyl isobutyl ketone two-phase solvent. BACKGROUND

[0002] Renewable lignocellulosic biomass is a low-cost energy source that can replace fossil raw materials for producing high-value-added chemicals and biofuels. Lignocellulosic biomass helps to alleviate global warming due to its carbon sequestration properties, while promoting sustainable economic development. However, the complex structure of lignocellulosic biomass makes it difficult to degrade, which not only reduces the chemical decomposition efficiency, but also restricts its application efficiency.

[0003] China, as the world's major cotton producer, has a large amount of cotton stalks as byproducts, which have not been fully utilized. In order to realize the high-value conversion of cotton stalk biomass, it is necessary to separate lignin, cellulose and hemicellulose by effective methods.

[0004] Traditional extraction methods have obvious shortcomings in safety, cost and efficiency, which limit the application of biomass. Deep eutectic solvents are widely used in biomass extraction due to their green, low toxicity and biodegradability. After deep eutectic solvent treatment, lignin will be dissolved in the solvent, while cellulose will hardly be dissolved, and hemicellulose will be converted into small molecular sugars and then into furfural. Therefore, deep eutectic solvent can be used as an efficient method for separating the three major elements.

[0005] Therefore, in order to solve the above technical problems in the prior art, it is an urgent technical problem for those skilled in the art to provide a method for separating cotton stalk lignin and byproduct furfural by using a deep eutectic solvent-methyl isobutyl ketone two-phase solvent, which is safe, low in cost and high in efficiency. SUMMARY

[0006] Therefore, the application provides a method for separating cotton stalk lignin and byproduct furfural by using a deep eutectic solvent-methyl isobutyl ketone two-phase solvent.

[0007] To solve the above technical problems, the application adopts the following technical solutions:

[0008] The application provides a method for separating cotton stalk lignin and byproduct furfural by using a deep eutectic solvent-methyl isobutyl ketone two-phase solvent, which comprises the following steps:

[0009] Step 1: Preparation of a deep eutectic solvent

[0010] Take tetramethylammonium chloride, formic acid and ethylene glycol in a reactor, heat to obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol deep eutectic solvent, and reserve;

[0011] Step 2: Treatment of cotton stalks with deep eutectic solvent-methyl isobutyl ketone two-phase solvent

[0012] The sieved and dried cotton stalk powder was added to the reactor, the deep eutectic solvent was added, and the mixture was stirred and heated. After the reaction was completed, methyl isobutyl ketone was added to the reactor, and the mixture was stirred to obtain a deep eutectic solvent-methyl isobutyl ketone cotton stalk treatment solution and solid-phase cellulose, which were ready for use.

[0013] Step 3: Separation of lignin and furfural

[0014] The treatment solution and solid-phase cellulose were subjected to suction filtration and rinsing, and the solid-phase cellulose was vacuum dried to obtain dried cellulose.

[0015] The deep eutectic solvent-methyl isobutyl ketone treatment solution was allowed to stand and separate into an upper layer containing furfural-containing methyl isobutyl ketone organic phase and a lower layer containing lignin-containing deep eutectic solvent phase.

[0016] The lower layer of deep eutectic solvent phase was added to deionized water, allowed to stand and settle, and subjected to suction filtration to obtain lignin solids, which were freeze-dried to obtain dried lignin.

[0017] The upper layer of furfural-containing methyl isobutyl ketone organic phase was subjected to rotary evaporation to recover methyl isobutyl ketone and obtain a furfural solution.

[0018] The furfural was diluted with methyl isobutyl ketone to a constant volume, and the furfural content was determined.

[0019] Preferably, in step 1, the molar ratio of tetramethylammonium chloride, formic acid, and ethylene glycol is tetramethylammonium chloride:formic acid:ethylene glycol = 1:5:0.1-1.

[0020] Preferably, in step 1, heating is carried out at 400 r / min to 60-80°C for 30-60 min to obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol deep eutectic solvent.

[0021] Preferably, in step 2, the dried cotton stalk powder is sieved through a 100-mesh sieve, and the weight ratio of the dried cotton stalk powder to the deep eutectic solvent is 1:20-50.

[0022] Preferably, in step 2, the mixture is stirred uniformly at 400 r / min and heated to 120-160°C for 6 h. After the reaction is completed, 50 parts by weight of methyl isobutyl ketone is added to the reactor, and the mixture is stirred at 500 r / min for 6 h to obtain a deep eutectic solvent-methyl isobutyl ketone cotton stalk treatment solution and solid-phase cellulose.

[0023] Preferably, in step 3, the treatment solution and solid-phase cellulose are subjected to suction filtration and rinsing with anhydrous ethanol 3-5 times, and the solid-phase cellulose is vacuum dried at 60°C for 6 h to obtain dried cellulose.

[0024] Preferably, in step 3, 300-500 parts by weight of deionized water is added to the lower eutectic solvent phase, and the mixture is allowed to stand and settle at 4°C for 24 hours, and then filtered to obtain lignin solids, which are dried by freeze-drying for 24 hours to obtain dried lignin.

[0025] Preferably, in step 3, the upper layer containing the methyl isobutyl ketone organic phase containing furfural is separated by rotary evaporation at 55°C to recover the methyl isobutyl ketone, thereby obtaining a furfural solution.

[0026] Preferably, in step 3, the weight of furfural is 1 part, and the content of furfural is determined by liquid chromatography with a mobile phase of methanol / water at a flow rate of 0.5 mL / min, a column temperature of 303 K, and a detection wavelength of 280 nm.

[0027] The volume ratio of methanol to water is 60:40.

[0028] The present application has the following technical effects compared to the prior art:

[0029] (1) Compared to conventional lignin extraction, the eutectic solvent has stronger destructive power on the hydrogen bonds between lignin, cellulose and hemicellulose, thereby improving the extraction efficiency of lignin.

[0030] (2) The addition of methyl isobutyl ketone can recover the furfural byproduct from the hemicellulose after eutectic solvent treatment, thereby improving the utilization of biomass.

[0031] (3) The raw materials involved in the present application are simple and easy to obtain, and the cost is low, which meets the development requirements of green development. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 SEM images of cotton stalks before and after treatment by the method of the present application for separating cotton stalk lignin and furfural byproduct using eutectic solvent-methyl isobutyl ketone two-phase solvent;

[0033] Wherein, a is the cotton stalk raw material; b is the cellulose obtained after treatment;

[0034] Figure 2 The amount of lignin and furfural byproduct separated by the method of the present application for separating cotton stalk lignin and furfural byproduct using eutectic solvent-methyl isobutyl ketone two-phase solvent;

[0035] Wherein, a is the extraction amount of lignin per gram of cotton stalk; b is the extraction amount of furfural per gram of cotton stalk. DETAILED DESCRIPTION

[0036] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0037] The application discloses a method for separating cotton stalk lignin and byproduct furfural by using a eutectic solvent-methyl isobutyl ketone two-phase solvent, which comprises the following steps:

[0038] Step 1: preparation of a eutectic solvent

[0039] Take tetramethylammonium chloride, formic acid and ethylene glycol in a reactor, heat, and obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol eutectic solvent for standby use.

[0040] Step 2: treatment of cotton stalk by using a eutectic solvent-methyl isobutyl ketone two-phase solvent

[0041] Take the sieved and dried cotton stalk powder into the reactor, add the eutectic solvent, stir uniformly, heat, add methyl isobutyl ketone into the reactor after the reaction is completed, stir, and obtain a eutectic solvent-methyl isobutyl ketone cotton stalk treatment liquid and solid-phase cellulose for standby use.

[0042] Step 3: separation of lignin and furfural

[0043] Perform suction filtration and flushing on the treatment liquid and the solid-phase cellulose, vacuum dry the solid-phase cellulose, and obtain dried cellulose.

[0044] Let the eutectic solvent-methyl isobutyl ketone treatment liquid stand to be layered, separate the upper-layer methyl isobutyl ketone organic phase containing furfural from the lower-layer eutectic solvent phase containing lignin.

[0045] Add deionized water to the lower-layer eutectic solvent phase, let it stand to be settled, perform suction filtration to obtain lignin solid, and obtain dried lignin after freeze-drying.

[0046] Recover methyl isobutyl ketone from the upper-layer methyl isobutyl ketone organic phase containing furfural by rotary evaporation, and obtain a furfural solution.

[0047] Take the furfural, dilute and constant-volume with methyl isobutyl ketone, and determine the furfural content.

[0048] In step 1, the molar ratio of tetramethylammonium chloride, formic acid and ethylene glycol is 1:5:0.1-1.

[0049] In step 1, heat to 60-80 DEG C at 400 r / min, and react for 30-60 min to obtain the clear tetramethylammonium chloride-formic acid-ethylene glycol eutectic solvent.

[0050] In step 2, the dry cotton stalk powder is passed through a 100-mesh sieve, and the weight ratio of the dry cotton stalk powder to the eutectic solvent is 1:20-50.

[0051] In step 2, the mixture is stirred at a speed of 400 r / min and heated to 120-160°C for 6 h. After the reaction is completed, 50 parts of methyl isobutyl ketone is added to the reactor, and the mixture is stirred at a speed of 500 r / min for 6 h to obtain a eutectic solvent-methyl isobutyl ketone cotton stalk treatment solution and solid cellulose.

[0052] In step 3, the treatment solution and the solid cellulose are subjected to suction filtration and washed with anhydrous ethanol for 3-5 times. The solid cellulose is vacuum dried at 60°C for 6 h to obtain dry cellulose.

[0053] In step 3, the lower eutectic solvent phase is added with 300-500 parts of deionized water, and the mixture is allowed to stand and settle at 4°C for 24 h. The lignin solid is obtained by suction filtration, and the dry lignin is obtained by freeze-drying for 24 h.

[0054] In step 3, the upper methyl isobutyl ketone organic phase containing furfural is separated by rotary evaporation at 55°C to recover the methyl isobutyl ketone, and a furfural solution is obtained.

[0055] In step 3, the weight ratio of the furfural to the methanol / water mobile phase is 1:60:40.

[0056] In step 3, the weight ratio of the furfural to the methanol / water mobile phase is 1:60:40.

[0057] Example 1:

[0058] Step 1: Preparation of the eutectic solvent

[0059] According to the molar ratio of tetramethylammonium chloride:formic acid:ethylene glycol = 1:5:0.1, the mixture is added to the reactor and heated to 60°C at a speed of 400 r / min for 30 min to obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol eutectic solvent, which is ready for use.

[0060] Step 2: Treatment of the cotton stalk with the eutectic solvent-methyl isobutyl ketone two-phase solvent

[0061] In step 2, 1 part of dry cotton stalk powder is added to the reactor, and 35 parts of the eutectic solvent is added. The mixture is stirred at a speed of 400 r / min and heated to 120°C for 6 h. After the reaction is completed, 50 parts of methyl isobutyl ketone is added to the reactor, and the mixture is stirred at a speed of 500 r / min for 6 h to obtain a eutectic solvent-methyl isobutyl ketone cotton stalk treatment solution and solid cellulose, which is ready for use.

[0062] Step 3: Separation of lignin and furfural

[0063] The above treatment liquid and solid cellulose were suction filtered and washed with anhydrous ethanol for 3 times, and the solid cellulose was vacuum dried at 60°C for 6h to obtain dried cellulose;

[0064] The low eutectic solvent-methyl isobutyl ketone treatment liquid was allowed to stand and separate into an upper layer of methyl isobutyl ketone organic phase containing furfural and a lower layer of low eutectic solvent phase containing lignin;

[0065] The lower layer of low eutectic solvent phase was added with 300 parts of deionized water, and allowed to stand and settle at 4°C for 24h, and then suction filtered to obtain lignin solid, which was freeze-dried for 24h to obtain dried lignin 0.054g;

[0066] The upper layer of methyl isobutyl ketone organic phase containing furfural was recovered by rotary evaporation at 55°C to obtain a furfural solution;

[0067] 1 part of furfural was diluted with methyl isobutyl ketone to constant volume, and the furfural content was determined by liquid chromatography with methanol / water (60:40 by volume) as the mobile phase, a flow rate of 0.5mL / min, a column temperature of 303k, and a detection wavelength of 280nm. The furfural content was 336.39mg / L.

[0068] Example 2:

[0069] Step 1: Preparation of low eutectic solvent

[0070] According to the molar ratio of tetramethylammonium chloride:formic acid:ethylene glycol = 1:5:0.1, the reactor was added, heated to 60°C at 400r / min, and reacted for 30min to obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol low eutectic solvent, which was prepared for use;

[0071] Step 2: Low eutectic solvent-methyl isobutyl ketone two-phase solvent treatment of cotton stalks

[0072] 1 part of dry cotton stalk powder passing through a 100 mesh sieve was added to the reactor, 50 parts of low eutectic solvent was added, and the mixture was stirred uniformly at a speed of 400r / min, and then heated to 160°C and reacted for 6h. After the reaction was completed, 50 parts of methyl isobutyl ketone was added to the reactor, and the mixture was stirred at a speed of 500r / min for 6h to obtain a low eutectic solvent-methyl isobutyl ketone cotton stalk treatment liquid and solid cellulose, which was prepared for use;

[0073] Step 3: Separation of lignin and furfural

[0074] The above treatment liquid and solid cellulose were suction filtered and washed with anhydrous ethanol for 3 times, and the solid cellulose was vacuum dried at 60°C for 6h to obtain dried cellulose;

[0075] The low eutectic solvent-methyl isobutyl ketone treatment solution is allowed to stand and separate into an upper layer of methyl isobutyl ketone organic phase containing furfural and a lower layer of low eutectic solvent phase containing lignin;

[0076] The lower layer of low eutectic solvent phase is added with 300 parts of deionized water, and allowed to stand and settle at 4°C for 24 h. Lignin solid is obtained by suction filtration. After being freeze-dried for 24 h, dry lignin 0.154 g is obtained.

[0077] The upper layer of methyl isobutyl ketone organic phase containing furfural is recovered by rotary evaporation at 55°C to obtain a furfural solution.

[0078] 1 part of furfural is diluted with methyl isobutyl ketone to constant volume. The furfural content is determined by liquid chromatography with methanol / water (60:40 by volume) as the mobile phase, a flow rate of 0.5 mL / min, a column temperature of 303 K, and a detection wavelength of 280 nm. The furfural content is 398.61 mg / L.

[0079] Example 3:

[0080] Step 1: Preparation of low eutectic solvent

[0081] According to the molar ratio of tetramethylammonium chloride: formic acid: ethylene glycol = 1:5:0.5, the reactor is added, heated to 70°C at 400 r / min, and reacted for 45 min to obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol low eutectic solvent, which is ready for use.

[0082] Step 2: Treatment of cotton stalks with low eutectic solvent-methyl isobutyl ketone two-phase solvent

[0083] 1 part of dry cotton stalk powder passing through a 100-mesh sieve is added to the reactor, 50 parts of low eutectic solvent is added, and stirred uniformly at a rotation speed of 400 r / min. The mixture is heated to 120°C and reacted for 6 h. After the reaction is completed, 50 parts of methyl isobutyl ketone is added to the reactor, and stirred at a rotation speed of 500 r / min for 6 h to obtain a low eutectic solvent-methyl isobutyl ketone cotton stalk treatment solution and solid-phase cellulose, which are ready for use.

[0084] Step 3: Separation of lignin and furfural

[0085] The above treatment solution and solid-phase cellulose are suction-filtered and rinsed with anhydrous ethanol 4 times. The solid-phase cellulose is vacuum-dried at 60°C for 6 h to obtain dry cellulose.

[0086] The low eutectic solvent-methyl isobutyl ketone treatment solution is allowed to stand and separate into an upper layer of methyl isobutyl ketone organic phase containing furfural and a lower layer of low eutectic solvent phase containing lignin;

[0087] The low eutectic solvent phase of the lower layer was added with 400 parts of deionized water, and was allowed to stand and settle at 4°C for 24 h. The lignin solid was obtained by suction filtration, and dried lignin 0.145 g was obtained after freeze-drying for 24 h;

[0088] The methyl isobutyl ketone organic phase containing furfural in the upper layer was separated by rotary evaporation at 55°C to recover the methyl isobutyl ketone, and a furfural solution was obtained;

[0089] 1 part of furfural was diluted with methyl isobutyl ketone to constant volume. The furfural content was determined by liquid chromatography with methanol / water (60:40 by volume) as the mobile phase, a flow rate of 0.5 mL / min, a column temperature of 303 K, and a detection wavelength of 280 nm. The furfural content was 185.88 mg / L.

[0090] Example 4:

[0091] Step 1: Preparation of a low eutectic solvent

[0092] According to the molar ratio of tetramethylammonium chloride: formic acid: ethylene glycol = 1:5:0.5, the reactor was added, heated to 70°C at 400 r / min, and reacted for 45 min to obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol low eutectic solvent, which was prepared for use;

[0093] Step 2: Treatment of cotton stalks with low eutectic solvent-methyl isobutyl ketone two-phase solvent

[0094] 1 part of dry cotton stalk powder passing through a 100-mesh sieve was added to the reactor, 35 parts of low eutectic solvent was added, and the mixture was stirred uniformly at a rotation speed of 400 r / min. The mixture was heated to 160°C and reacted for 6 h. After the reaction was completed, 50 parts of methyl isobutyl ketone was added to the reactor, and the mixture was stirred at a rotation speed of 500 r / min for 6 h to obtain a low eutectic solvent-methyl isobutyl ketone cotton stalk treatment liquid and solid-phase cellulose, which were prepared for use;

[0095] Step 3: Separation of lignin and furfural

[0096] The treatment liquid and solid-phase cellulose were suction-filtered and washed with anhydrous ethanol 4 times. The solid-phase cellulose was vacuum-dried at 60°C for 6 h to obtain dried cellulose. The electron microscope image of the dried cellulose showed that the surface had obvious signs of damage and presented an irregular shape, as compared with the electron microscope image of the raw material.

[0097] The low eutectic solvent-methyl isobutyl ketone treatment liquid was allowed to stand and separate into an upper layer containing methyl isobutyl ketone organic phase with furfural and a lower layer containing low eutectic solvent phase with lignin;

[0098] The low eutectic solvent phase of the lower layer was added with 400 parts of deionized water, and was allowed to stand and settle at 4°C for 24 h. The lignin solid was obtained by suction filtration, and dried lignin 0.145 g was obtained after freeze-drying for 24 h;

[0099] The upper organic phase containing furfural and methyl isobutyl ketone was separated and the methyl isobutyl ketone was recovered by rotary evaporation at 55°C to obtain a furfural solution;

[0100] One part of furfural was diluted with methyl isobutyl ketone and brought to a final volume. The solution was then passed through a liquid chromatography system with methanol / water (60:40 volume ratio) as the mobile phase, a flow rate of 0.5 mL / min, a column temperature of 303 K, and a detection wavelength of 280 nm. The furfural content was determined to be 441.32 mg / L.

[0101] Example 5:

[0102] Step 1: Preparation of eutectic solvent

[0103] Add tetramethylammonium chloride:formic acid:ethylene glycol in a molar ratio of 1:5:1 to the reactor, heat to 80°C at 400 r / min, and react for 60 min to obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol eutectic solvent for later use.

[0104] Step 2: Treat cotton stalks with a eutectic solvent-methyl isobutyl ketone biphase solvent.

[0105] Take 1 part of dried cotton stalk powder that has passed through a 100-mesh sieve and add it to the reactor. Add 20 parts of eutectic solvent and stir evenly at 400 r / min. Heat to 120℃ and react for 6 h. After the reaction is complete, add 50 parts of methyl isobutyl ketone to the reactor and stir at 500 r / min for 6 h to obtain eutectic solvent-methyl isobutyl ketone cotton stalk treatment solution and solid cellulose for later use.

[0106] Step 3: Separate lignin and furfural

[0107] The above-mentioned treatment solution and solid cellulose were filtered and washed 5 times with anhydrous ethanol. The solid cellulose was then vacuum dried at 60°C for 6 hours to obtain dried cellulose.

[0108] The eutectic solvent-methyl isobutyl ketone treatment solution was allowed to stand and separate into layers, and the upper layer containing furfural and the methyl isobutyl ketone organic phase and the lower layer containing lignin eutectic solvent phase were separated.

[0109] 500 parts of deionized water were added to the lower eutectic solvent phase, and the mixture was allowed to settle at 4°C for 24 h. The solid lignin was obtained by filtration and freeze-drying for 24 h to obtain 0.049 g of dried lignin.

[0110] The upper organic phase containing furfural and methyl isobutyl ketone was separated and the methyl isobutyl ketone was recovered by rotary evaporation at 55°C to obtain a furfural solution;

[0111] One part of furfural was diluted with methyl isobutyl ketone and brought to volume. The solution was then passed through a liquid chromatography system with methanol / water (60:40 volume ratio) as the mobile phase, a flow rate of 0.5 mL / min, a column temperature of 303 K, and a detection wavelength of 280 nm. The furfural content was determined to be 92.49 mg / L.

[0112] Example 6:

[0113] Step 1: Preparation of eutectic solvent

[0114] Add tetramethylammonium chloride:formic acid:ethylene glycol in a molar ratio of 1:5:1 to the reactor, heat to 80°C at 400 r / min, and react for 60 min to obtain a clear tetramethylammonium chloride-formic acid-ethylene glycol eutectic solvent for later use.

[0115] Step 2: Treat cotton stalks with a eutectic solvent-methyl isobutyl ketone biphase solvent.

[0116] Take 1 part of dried cotton stalk powder that has passed through a 100-mesh sieve and add it to the reactor. Add 50 parts of eutectic solvent and stir evenly at 400 r / min. Heat to 140℃ and react for 6 h. After the reaction is complete, add 50 parts of methyl isobutyl ketone to the reactor and stir at 500 r / min for 6 h to obtain eutectic solvent-methyl isobutyl ketone cotton stalk treatment solution and solid cellulose for later use.

[0117] Step 3: Separate lignin and furfural

[0118] The above-mentioned treatment solution and solid cellulose were filtered and washed 5 times with anhydrous ethanol. The solid cellulose was then vacuum dried at 60°C for 6 hours to obtain dried cellulose.

[0119] The eutectic solvent-methyl isobutyl ketone treatment solution was allowed to stand and separate into layers, and the upper layer containing furfural and the methyl isobutyl ketone organic phase and the lower layer containing lignin eutectic solvent phase were separated.

[0120] 500 parts of deionized water were added to the lower eutectic solvent phase, and the mixture was allowed to settle at 4°C for 24 h. The solid lignin was obtained by filtration and freeze-drying for 24 h to obtain 0.125 g of dried lignin.

[0121] The upper organic phase containing furfural and methyl isobutyl ketone was separated and the methyl isobutyl ketone was recovered by rotary evaporation at 55°C to obtain a furfural solution;

[0122] One part of furfural was diluted with methyl isobutyl ketone and brought to a final volume. The solution was then passed through a liquid chromatography system with methanol / water (60:40 volume ratio) as the mobile phase, a flow rate of 0.5 mL / min, a column temperature of 303 K, and a detection wavelength of 280 nm. The furfural content was determined to be 357.96 mg / L.

[0123] like Figure 1The image shows SEM images comparing cotton stalks before and after treatment using the eutectic solvent-methyl isobutyl ketone two-phase solvent method of the present invention for separating lignin and furfural byproducts from cotton stalks; a is the raw cotton stalk; b is the cellulose obtained after treatment.

[0124] like Figure 2 The figure shows the amount of lignin and furfural separated by the eutectic solvent-methyl isobutyl ketone biphase solvent method of the present invention; a is the amount of lignin extracted per gram of cotton stalk; b is the amount of furfural extracted per gram of cotton stalk.

[0125] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method of separating cotton stalk lignin and by-product furfural using deep eutectic solvent-methyl isobutyl ketone biphasic solvent, characterized in that, Comprising the following steps: Step 1: preparation of the eutectic solvent Take tetramethylammonium chloride, formic acid and ethylene glycol in a reactor, heat to obtain clear tetramethylammonium chloride-formic acid-ethylene glycol eutectic solvent, ready for use; Step 2: eutectic solvent-methyl isobutyl ketone two-phase solvent treatment of cotton stalk Take the dry cotton stalk powder sieved and add it to the reactor, add the eutectic solvent, stir until uniform, heat, after the reaction is complete, add methyl isobutyl ketone to the reactor, stir to obtain a eutectic solvent-methyl isobutyl ketone cotton stalk treatment liquid and solid phase cellulose, ready for use; Step 3: separation of lignin and furfural The treatment liquid and solid phase cellulose are suction filtered and rinsed, the solid phase cellulose is vacuum dried to obtain dry cellulose; The eutectic solvent-methyl isobutyl ketone treatment liquid is allowed to stand and separate into an upper layer of methyl isobutyl ketone organic phase containing furfural and a lower layer of eutectic solvent phase containing lignin; The lower layer of eutectic solvent phase is added to deionized water, allowed to stand and settle, suction filtered to obtain lignin solids, which are freeze-dried to obtain dry lignin; The upper layer of methyl isobutyl ketone organic phase containing furfural is separated by rotary evaporation to recover methyl isobutyl ketone and obtain a furfural solution; The furfural is diluted with methyl isobutyl ketone to constant volume and the furfural content is determined.

2. A method of separating cotton stalk lignin and by-product furfural using deep eutectic solvent-methyl isobutyl ketone biphasic solvent according to claim 1, characterized in that, In step 1, the molar ratio of tetramethylammonium chloride, formic acid and ethylene glycol is tetramethylammonium chloride:formic acid:ethylene glycol = 1:5:0.1-1.

3. The method of separating cotton lignin and byproduct furfural using deep eutectic solvent-methyl isobutyl ketone biphasic solvent according to claim 1, characterized in that, In step 1, heating is carried out at 400 r / min to 60-80°C for 30-60 min to obtain clear tetramethylammonium chloride-formic acid-ethylene glycol eutectic solvent.

4. The method of separating cotton lignin and byproduct furfural from a low eutectic solvent-methyl isobutyl ketone biphasic solvent according to claim 1, wherein, In step 2, the dry cotton stalk powder is sieved through a 100 mesh sieve and the weight ratio of the dry cotton stalk powder to the eutectic solvent is 1:20-50.

5. The method of claim 1, wherein the method is characterized by, In step 2, the mixture is stirred at 400 r / min until uniform, heated to 120-160°C for 6 h, after the reaction is complete, 50 parts by weight of methyl isobutyl ketone is added to the reactor, stirred at 500 r / min for 6 h to obtain a eutectic solvent-methyl isobutyl ketone cotton stalk treatment liquid and solid phase cellulose.

6. The method of separating cotton lignin and byproduct furfural from a low eutectic solvent-methyl isobutyl ketone biphasic solvent according to claim 1, wherein, In step 3, the treatment liquid and solid phase cellulose are suction filtered and rinsed with anhydrous ethanol 3-5 times, the solid phase cellulose is vacuum dried at 60°C for 6 h to obtain dry cellulose.

7. The method of claim 1, wherein the method is characterized by, In step 3, the lower layer of eutectic solvent phase is added to 300-500 parts by weight of deionized water, allowed to stand and settle at 4°C for 24 h, suction filtered to obtain lignin solids, which are freeze-dried for 24 h to obtain dry lignin.

8. The method of claim 1, wherein the method is characterized by, In step 3, the upper layer of methyl isobutyl ketone organic phase containing furfural is separated by rotary evaporation at 55°C to recover methyl isobutyl ketone and obtain a furfural solution.

9. The method of claim 1, wherein the method is characterized by, In step 3, the furfural is 1 part by weight, the liquid phase is used to determine the furfural content with methanol / water as the mobile phase, a flow rate of 0.5 mL / min, a column temperature of 303 k and a detection wavelength of 280 nm; The volume ratio of methanol to water is 60:40.

Images