A CO2-responsive biomass-based foaming agent

Abstract

The present invention discloses a CO2-responsive biomass-based foaming agent. Its structural formula is shown as Formula I. The present invention uses inexpensive and environmentally friendly gluconic acid as a raw material to prepare a biomass-based foaming agent with CO2 responsiveness, and the synthesis process is simple. The gluconic acid-based foaming agent prepared by the present invention has the characteristics of strong surface tension reduction ability, good foaming performance, low dosage, and the formed stable foam has CO2 responsiveness. It can be gently defoamed by gaseous CO2 without destroying the original system, which conforms to the development direction of green environmental protection.

Description

Technical Field

[0001] The present invention relates to the technical field of surfactant science and application, and particularly relates to a CO2-responsive biomass-based foaming agent. Background Art

[0002] In many actual production processes, the foaming agent not only needs to form stable foam to ensure the requirements of the production process, but also needs to be easily destroyed after the foam is used to simplify the post-treatment process. For most surfactants, the best foaming performance can only be achieved above the critical micelle concentration. Therefore, a large amount of surfactants are used as foaming agents every year, which not only increases the production cost, but also brings many challenges to the post-treatment process and environmental safety after the foam is used. Therefore, it is of great significance to develop a stimulus-responsive foam system that can change the surrounding environment through a mild and simple method to achieve efficient foaming / defoaming.

[0003] Biomass-based surfactants are derived from abundant renewable resources and belong to mild surfactants that are non-toxic and easily biodegradable. They have great potential in the applications of many fields such as cleaning products, cosmetics, and food. Considering environmental and sustainable development issues, the advantages of non-toxic and renewable surfactants will become more and more significant in future production applications. Summary of the Invention

[0004] The purpose of the present invention is to provide a biomass-based foaming agent with CO2 responsiveness.

[0005] The biomass-based foaming agent with CO2 responsiveness provided by the present invention has a structural formula as shown in Formula I:

[0006]

[0007] In Formula I, R1 and R2 are the same or different, and R1 and R2 each independently selected from: alkyl groups of (C1–C 22 ), alkenyl groups of (C2-C 22 ), aryl groups substituted with alkyl groups (C7-C 22 ), aryl groups substituted with alkenyl groups (C8-C 22 ) or cycloalkyl groups (C5-C 12 );

[0008] In Formula I, X can be any one of Na + , K + , Ca 2+ , Li + , Cs + ;

[0009] The compound shown in Formula I can specifically be the compound shown in Formula I-A below:

[0010]

[0011] The compound shown in the above formula I is prepared by a method comprising the following steps: reacting gluconic acid with aldehydes R1CHO and R2CHO under the catalysis of an acidic catalyst to obtain an acetal-substituted gluconic acid ester, and further hydrolyzing it under alkaline conditions to obtain an acetal-substituted gluconate, i.e., the compound shown in formula I. The reaction formula is as follows:

[0012]

[0013] R1, R2, and X are defined as in R1, R2, and X in formula I;

[0014] In the above preparation method, the molar ratio of gluconic acid to aldehydes R1CHO and R2CHO can be 1:(1 - 4):(1 - 4), specifically 1:3:3;

[0015] The acidic catalyst can be one of p-toluenesulfonic acid (p-TSA), camphorsulfonic acid (CSA), concentrated sulfuric acid, or acidic resin A15, acidic zeolite, mesoporous silica. The amount of the acidic catalyst is 3 - 10 mol% of the total amount of aldehydes, preferably 5 mol%.

[0016] The temperature of the reaction can be 40 - 150 °C, preferably 80 °C, and the time can be 4 - 24 hours, preferably 12 hours.

[0017] The alkaline condition can be provided by any one of sodium hydroxide, potassium hydroxide, calcium hydroxide, cesium hydroxide, and lithium hydroxide, preferably sodium hydroxide.

[0018] The reaction is carried out in an organic solvent, which can be any one of methanol, ethanol, toluene, acetonitrile, dioxane, etc., preferably ethanol.

[0019] The temperature of the hydrolysis can be room temperature, and the time can be 5 - 10 hours, specifically 5 h.

[0020] The present invention also provides the application of the compound shown in the above formula I as a foaming agent or in the preparation of a foaming agent.

[0021] In the above application, the foaming agent is a CO2-responsive foaming agent.

[0022] The present invention also provides a CO2-responsive foaming system.

[0023] The CO2-responsive foaming system provided by the present invention is prepared by dissolving the compound shown in formula I in water and bubbling nitrogen. Among them, the concentration of the compound shown in formula I can be 0.8 - 4% (W / W), specifically 0.8% (W / W).

[0024] The present invention also provides a foaming method using the compound shown in the above formula I.

[0025] For the foaming method provided by the present invention, the compound shown in formula I is added to the system, and then rapidly stirred or nitrogen is introduced to foam. After the foam is used up, CO2 is introduced to eliminate the foam.

[0026] In the above method, in the system, the concentration of the compound shown in formula I can be 0.8-4% (W / W).

[0027] The present invention has the following effects:

[0028] The present invention uses inexpensive and environmentally friendly gluconic acid as a raw material to prepare a biomass-based foaming agent with CO2 responsiveness, and the synthesis process is simple. The gluconic acid-based foaming agent prepared by the present invention has the characteristics of strong ability to reduce surface tension, good foaming performance, small dosage, and the formed stable foam has CO2 responsiveness, etc. It can be gently defoamed by the gas CO2 without destroying the original system, which conforms to the development direction of green environmental protection. Brief Description of the Drawings

[0029] Figure 1 It is the surface tension-concentration curve of the gluconic acid-based foaming agent prepared in Example 1.

[0030] Figure 2 It is the evaluation of the foam performance of the gluconic acid-based foaming agent prepared in Example 1.

[0031] Figure 3 It is the evaluation of the CO2 responsiveness of the foam system of the gluconic acid-based foaming agent prepared in Example 1. Detailed Description of the Invention

[0032] The following further describes the present invention in detail in combination with specific embodiments. The given embodiments are only for clarifying the present invention, rather than limiting the scope of the present invention. The following provided embodiments can be used as a guide for those of ordinary skill in the art to make further improvements, and do not limit the present invention in any way.

[0033] The experimental methods in the following embodiments, unless otherwise specified, are all conventional methods, and are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. The materials, reagents, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial channels.

[0034] Example 1. Synthesis of the acetal-substituted sodium gluconate foaming agent shown in formula I-A

[0035] The acetal-substituted sodium gluconate foaming agent I-A (G-GAC8) is synthesized according to the route of formula I-A. The specific steps are as follows:

[0036] (1) 50 mM of freeze-dried gluconic acid and 300 mM of octanal were added to 25 mL of anhydrous ethanol. 5% mol (relative to the molar amount of octanal) of camphorsulfonic acid was added to this system. Under nitrogen protection, the mixed system was placed in an 80 °C oil bath and reacted for 12 h. After the reaction, ethanol in the system was removed by rotary evaporation under vacuum. At this time, the reactant was in a brown viscous liquid state, and the reactant was extracted with ethyl acetate and water. Among them, camphorsulfonic acid and unreacted gluconic acid would dissolve in the aqueous phase and be removed, and the ethyl acetate phase was the product and unreacted octanal. Ethyl acetate was removed again by vacuum concentration to obtain an oily substance. Then, 50 mL of 1.5 mM NaOH solution was added to the oily substance in the organic phase, and it was stirred at room temperature for 5 h. The formed white precipitate was recrystallized with acetone / ethanol V / V 3:1 to obtain a white solid with a yield of 76%. Its structure was confirmed by NMR and mass spectrometry, and the results were as follows:

[0037] Ⅰ-A: 1 H NMR (400 MHz, DMSO-d6) δ = 4.86 - 4.76 (m, 1H), 4.46 (t, J = 5.1 Hz, 1H), 4.10 (d, J = 7.1 Hz, 1H), 3.89 (dd, J = 10.2, 4.6 Hz, 1H), 3.64 (t, J = 7.5 Hz, 1H), 3.35 - 3.21 (m, 2H), 1.55 - 1.47 (dd, J = 9.1, 5.1 Hz, 4H), 1.38 - 1.21 (m, 22H), 0.86 (td, J = 6.8, 3.1 Hz, 6H). 13 C NMR (75 MHz, DMSO) δ = 174.47, 103.76, 101.22, 84.39, 81.86, 76.86, 69.97, 63.38, 34.56, 33.28, 31.76, 29.25, 24.27, 22.55, 14.27. ESI-MS: 438.3; Found: 437.6, (M-H).

[0038] Example 2. Surface activity evaluation of gluconic acid-based foaming agent

[0039] Surface tension measurement

[0040] Instrument: Dataphysics DCAT-21 surface tension measuring instrument (Dataphysics Company, Germany); The experimental temperature was controlled at (30 ± 0.1) °C by a BX-101 type constant temperature bath.

[0041] Measurement method: The equilibrium surface tension of a series of concentrations of acetal-substituted sodium gluconate foaming agents was measured at 30 °C using the Wilhelmy-plate method. Starting from a low concentration, the change in surface tension value over time was measured, and the value at the equilibrium point was taken as the equilibrium surface tension at that concentration.

[0042] A curve of surface tension against concentration was plotted to obtain the γ-logC curve, and the inflection point of the curve was the critical micelle concentration (CMC) of the foaming agent.

[0043] The experimental results are as Figure 1 shown. It can be seen from Figure 1 that the gluconic acid-based foaming agent of the present invention has a relatively low critical micelle concentration (cmc = 0.08 mmol / L) and a relatively significant ability to reduce the surface tension γ cmc = 32 mN / m.

[0044] Example 3. Evaluation of the foaming performance of the gluconic acid-based foaming agent

[0045] Measurement method: The present invention uses a foam column to evaluate the foaming ability of the foaming agent. The specific foaming ability evaluation process is as follows. 50 ml of the foaming agent solution is added to a 5000 ml foam column device. The outer layer of the foam column is passed through with circulating water at 30 °C to keep the internal temperature constant, thereby excluding the influence of temperature on the foam. Then, N2 is introduced into the foaming agent solution from the bottom of the foam column at a gas flow rate of 10 ml / s for 20 s. Driven by N2, the foaming agent that can form foam will form bubbles in the foam column. All experiments are carried out on the same device. At certain time intervals, the height of the foam above the liquid surface is recorded and plotted against time until the foam reaches half of the original height ( Figure 2 ).

[0046] Figure 2 a shows the variation law of the foaming height with time of the prepared foaming agent I-A (G-GAC8) and the control samples sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS), where SDS and SDBS are commercial foaming agents, and the concentrations used are both 1 mmol / L; Figure 2 b shows the comparison of the foam half-life of the prepared foaming agent I-A (G-GAC8) and the control samples SDS and SDBS. The foam half-life of the foaming agent I-A is significantly higher than that of the control samples, indicating that the foam formed by I-A is more stable at the same concentration; Figure 2 c is a micrograph of the foam formed by the foaming agent I-A, Figure 2 d is a micrograph of the foam formed by SDBS.

[0047] Example 4. Evaluation of the responsiveness of the CO2 to the gluconic acid-based foaming agent foam system and the cyclic experiment of CO2 response

[0048] Determination method: The present invention uses a foam column to evaluate the stability of the foam formed by the foaming agent. The specific foaming property evaluation process is as follows. 50 ml of the foaming agent solution is added to a foam column device with a capacity of 5000 ml. Circulating water at 30 °C is passed through the outer layer of the foam column to keep the internal temperature constant, thereby eliminating the influence of temperature on the foam. Then, N2 is introduced into the foaming agent solution from the bottom of the foam column at a gas flow rate of 10 ml / s for 20 s. Driven by N2, the foaming agent capable of foaming will form bubbles in the foam column. Record the height of the foam above the liquid surface. Subsequently, CO2 is introduced into the surfactant solution from the bottom of the foam column at a gas flow rate of 10 ml / s for 20 s, and record the change in foam height ( Figure 3 ). All experiments were carried out on the same device.

[0049] Figure 3 a and 3b are the responses of the prepared foaming agent Ⅰ-A (G-GAC8) aqueous solution (1 mmol / L) to CO2 gas. After introducing CO2, the pH value of the solution decreases and the turbidity of the solution increases. The lowest pH value can reach 4.7. After introducing N2, the solution becomes clear and the pH value can return to near neutral. Figure 3 c is the foaming property of the prepared foaming agent Ⅰ-A and the defoaming cycle experiment of CO2 gas, indicating that foam is generated when N2 is introduced and defoamed when CO2 is introduced, and the foaming and defoaming properties have gas responsiveness. CO2 can be used as an effective defoaming agent for this foaming agent.

[0050] The above details the present invention. For those skilled in the art, without departing from the purpose and scope of the present invention and without unnecessary experiments, the present invention can be implemented within a relatively wide range under equivalent parameters, concentrations, and conditions. Although specific embodiments of the present invention are given, it should be understood that the present invention can be further improved. In short, according to the principle of the present invention, this application intends to include any changes, uses, or improvements to the present invention, including those that depart from the scope disclosed in this application and are made using conventional techniques known in the art. Some basic features can be applied according to the scope of the following appended claims.

Claims

1. Use of the compound represented by Formula I-A as a blowing agent or in the preparation of a blowing agent; The structural formula of the compound represented by Formula I-A is as follows: The blowing agent is a CO2-responsive blowing agent.

2. A CO2-responsive foaming system, which is prepared by dissolving the compound represented by Formula I-A in claim 1 in water and bubbling nitrogen.

3. The CO2-responsive foaming system according to claim 2, characterized in that: In the said system, the mass percentage concentration of the compound shown by Formula I-A is 0.8% to 4%.

4. A foaming method, which is to add the compound represented by Formula I-A in claim 1 to the system, stir rapidly or bubble nitrogen, foam, and after the foam is used up, bubble CO2 to eliminate the foam.

5. The foaming method according to claim 4, characterized in that: In the said system, the mass percentage concentration of the compound shown by Formula I-A is 0.8% to 4%.

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