Method for preparing lignin amine cationic surfactant from papermaking byproduct black liquor in high-valued water phase

Abstract

The invention relates to the technical field of high-valued utilization of biomass, in particular to a method for preparing a lignin amine cationic surfactant from papermaking byproduct black liquor in a high-valued water phase, which comprises the following steps: adjusting the pH value of pulping black liquor by using acid or alkali, centrifuging to take supernatant liquid, adding epoxy chloropropane, heating to a certain temperature, and reacting for 30 minutes. And then adding an amine reagent to react for a certain time, cooling, centrifuging, washing, and drying the lower layer precipitate to obtain the lignin amine cationic surfactant. According to the method, the papermaking byproduct black liquor can be turned into wealth, the lignin amine cationic surface active agent is synthesized in a high-value water phase, the preparation process of the lignin amine cationic surface active agent is simple and low in energy consumption, the whole process is green and environment-friendly, no wastewater is discharged, the black liquor does not need to be purified, formaldehyde does not need to be added, and alkali recovery is also not needed; the industrial production is easy to realize, and the market prospect is wide.

Description

Technical Field

[0001] The invention relates to the technical field of high-value utilization of biomass, and more particularly to a method for preparing a lignin amine cationic surfactant from a water phase of a papermaking byproduct black liquor high-valued. Background Art

[0002] Concerns about excessive greenhouse gas emissions and the depletion of fossil fuel resources have prompted people to turn more urgently to renewable resources and relatively clean energy to replace fossil energy. Black liquor is a byproduct of alkaline pulping in the pulp production process. It is rich in lignin and is the largest natural source of aromatic hydrocarbons such as phenolic hydroxyl groups. The composition of pulping black liquor varies greatly from one mill to another, depending on the cooking process and the wood used, but the pollution caused by pulping black liquor is the same. Due to its high alkalinity and high COD content, pulping black liquor poses a serious threat to the environment and human health. How to convert pulping black liquor waste into useful products is of great significance. As we know, pulping black liquor is a black, viscous liquid with a special smell and rich in lignin. Lignin has a complex structure and is difficult to be biodegraded. It is one of the main sources of pollution in the world. Using lignin pulping black liquor to synthesize high value-added products is the best way to reduce pollution.

[0003] Lignin is the second most abundant renewable macromolecule on earth after cellulose and is considered one of the most promising organic resources among natural polymers. Lignin is abundant in plant cells and wood tissues. The content of lignin depends on the plant species and accounts for 15% to 30% of biomass. It is very important and necessary to strengthen the application research of lignin, which is of great significance for eliminating the pollution of pulping to the ecological environment and expanding the utilization of renewable resources. Lignin can be customized as a raw material for benzene derivatives, benzene and aromatic compounds. It can also be used as a surfactant, synthetic adhesive or fuel for paper mills, which has huge economic benefits. As a biomass, lignin has the characteristics of wide sources, low price, environmental friendliness, biodegradability and surface activity. Therefore, lignin has become one of the best raw materials for preparing biomass surfactants. The lignin salt originally used is an anionic organic compound with both hydrophilic and hydrophobic parts, so it has the function of anionic surfactants. Although lignin salt has certain surface activity, due to its wide molecular weight distribution, complex molecular structure, lack of regular lipophilic and hydrophilic groups, it is difficult to arrange regularly at the interface between the two phases, and its surface activity and application performance are limited. Among various surfactants, cationic surfactants have emulsifying and bactericidal properties and multifunctional applications in cosmetics and pharmaceutical preparations, and cationic surfactants are expected to become the most promising surfactants in the future. Therefore, it is necessary to modify lignin appropriately to meet the conditions for generating surface activity.

[0004] Patent CN201280066901.X provides a method for preparing lignin-amine. Kraft lignin or sulfate lignin is dissolved in a polar solvent (dimethylformamide, tetrahydrofuran, acetone, N-methyl-2-pyrrolidone, dimethyl sulfoxide or methanol, etc.), and an organic amine and an acyl-containing compound are added to react to obtain lignin-amine. Patent CN201611100373.1 dissolves lignin in an alkaline solution, adds a solid alkaline catalyst and an organic amine, heats to the required temperature, and then drips formaldehyde to react to obtain lignin amine.

[0005] Patent CN201510005045.2 discloses a method for preparing a phenolated lignin amine cationic emulsifier. First, phenol and alkali lignin are reacted under alkaline conditions, and phenolated lignin is obtained by phenolization modification without significantly increasing the molecular weight of lignin. Then, the phenolated lignin is reacted with diethylenetriamine and formaldehyde under alkaline conditions to obtain a phenolated lignin amine cationic emulsifier solution. The phenolated alkali lignin amine cationic emulsifier has better surface activity, higher Zeta potential and better emulsification performance than the control sample that has not been phenolized, and can be used in asphalt emulsification and other fields.

[0006] Patent CN202010446957.4 discloses a lignin cationic surfactant and a preparation method thereof, as well as a long-acting antibacterial agent and a preparation method thereof. The tertiary amine is acidified under acidic conditions, and then epichlorohydrin is added to react. The pH value of the system is adjusted to neutral and then the reaction is continued to obtain an intermediate product. Lignin is added to the intermediate product, and the pH value of the solution is adjusted to alkaline for grafting reaction to obtain a lignin cationic surfactant. The prepared surfactant has good hydrophilicity and good stability.

[0007] The above inventions all utilize pure lignin solids rather than directly using undried pulping black liquor to synthesize lignin amines; moreover, the synthesis environment is mostly organic phase or contains formaldehyde, and organic solvent synthesis has the problem of subsequent separation and recovery difficulties. Formaldehyde is an unfriendly reagent that will endanger human health. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a method for preparing lignin amine cationic surfactant by converting papermaking by-product black liquor into high-value aqueous phase, which can directly turn high-pH and highly polluted pulping black liquor discharged in the papermaking industry into treasure, and synthesize lignin amine cationic surfactant in high-value aqueous phase; the whole process is green and environmentally friendly, with no wastewater discharge, no need to purify the black liquor, no need to add formaldehyde, and no need for alkali recovery.

[0009] The present invention specifically adopts the following technical solutions:

[0010] A method for preparing a lignin amine cationic surfactant by converting a water phase of papermaking byproduct black liquor into a high-value aqueous phase comprises the following steps:

[0011] Take an appropriate amount of papermaking black liquor, adjust the pH of the pulping black liquor to a certain range with acid or alkali, centrifuge to take the supernatant, add an appropriate amount of epichlorohydrin, heat to a certain temperature and react for 30 minutes. Then add an appropriate amount of amine reagent, react for a certain time, cool, centrifuge, and dry the solid precipitate to obtain the lignin amine cationic surfactant.

[0012] Furthermore, the pH of the pulping black liquor is adjusted to 8-13 with acid or alkali.

[0013] Furthermore, the amount of epichlorohydrin added is 1.0-10.0 times the hydroxyl group contained in the lignin in the papermaking black liquor, based on the molar ratio.

[0014] Furthermore, the reaction temperature is 40-100°C.

[0015] Furthermore, the amount of the amine reagent added is 1.0-10.0 times the hydroxyl group contained in the lignin in the papermaking black liquor, based on the molar ratio.

[0016] Furthermore, the reaction time is 10-300 min.

[0017] Furthermore, after centrifugation and washing, the lower precipitate obtained is dried to obtain the lignin amine cationic surfactant.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention can directly synthesize the high-alkalinity, high-COD content pulping black liquor discharged from the papermaking industry into a high-value lignin amine cationic surfactant without the need to purify the black liquor, add formaldehyde, or recover alkali. The entire process is green and environmentally friendly, with no wastewater discharge.

[0020] (2) The method for synthesizing lignin amine cationic surfactants of the present invention is in an aqueous system rather than an organic system, which has lower production costs; the raw materials for synthesizing cationic surfactants are renewable, which effectively reduces the consumption of fossil energy and helps achieve the goal of carbon neutrality.

[0021] (3) The lignin amine cationic surfactant synthesized in the present invention can not only be used as a surfactant to reduce surface tension, but also can be used as a curing agent for epoxy asphalt, and has multifunctional application properties.

[0022] (4) The present invention transforms highly polluting pulping black liquor into valuable materials to produce high-value lignin amine cationic surfactants, which has simple process, low energy consumption and short production cycle, and provides technical support for the large-scale production of lignin amine cationic surfactants. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The process route of the invention for high-value aqueous synthesis of lignin amine cationic surfactants from papermaking black liquor DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with the accompanying drawings and specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources.

[0025] Example 1

[0026] Take 50 mL of pulping black liquor and adjust the pH to 11, add 0.5 mL of epichlorohydrin, and heat to 60 ° C for 30 minutes. Then, add 0.9 mL of n-butylamine and react for 30 minutes, cool, centrifuge, wash the lower precipitate and dry to obtain lignin amine cationic surfactant. The surface tension (2.5 mg / mL) of the lignin amine cationic surfactant is 49.83 mN / m.

[0027] Example 2

[0028] Take 50 mL of pulping black liquor and adjust the pH to 12, add 0.7 mL of epichlorohydrin, and heat to 50 ° C for 30 minutes. Then, add 0.7 mL of n-butylamine and react for 30 minutes, cool, centrifuge, wash the lower precipitate and dry to obtain lignin amine cationic surfactant. The surface tension (2.5 mg / mL) of the lignin amine cationic surfactant is 48.71 mN / m.

[0029] Example 3

[0030] Take 50 mL of pulping black liquor and adjust the pH to 10, add 0.5 mL of epichlorohydrin, and heat to 80 ° C for 30 minutes. Then, add 0.7 mL of n-butylamine and react for 1 hour, cool, centrifuge, wash the lower precipitate and dry to obtain lignin amine cationic surfactant. The surface tension of the lignin amine cationic surfactant (2.5 mg / mL) is 47.45 mN / m.

[0031] Example 4

[0032] Take 50 mL of pulping black liquor and adjust the pH to 11, add 0.9 mL of epichlorohydrin, and heat to 60 ° C for 30 minutes. Then, add 0.9 mL of n-butylamine and react for 2 hours, cool, centrifuge, wash the lower precipitate and dry to obtain lignin amine cationic surfactant. The surface tension of the lignin amine cationic surfactant (2.5 mg / mL) is 46.81 mN / m.

[0033] Example 5

[0034] Take 50mL of pulping black liquor and adjust the pH to 12, add 1mL of epichlorohydrin, and heat to 70℃ for 30min. Then, add 1mL of n-butylamine and react for 2h, cool, centrifuge, wash the lower precipitate and dry to obtain lignin amine cationic surfactant. The surface tension (2.5mg / mL) of the lignin amine cationic surfactant is 47.47mN / m.

[0035] It can be seen from Table 1 that the surface tension (2.5 mg / L) of the lignin amine cationic surfactants prepared in Examples 1-5 is less than that of deionized water and the solid after pulping black liquor is dried, which indicates that lignin amine cationic surfactants with good surface activity can also be obtained from pulping black liquor in an aqueous phase and without aldehydes.

[0036] It should be noted that when the claims of the present invention involve numerical ranges, it should be understood that the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. In order to avoid redundancy, the present invention describes a preferred embodiment.

[0037] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0038] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0039] Table 1 Surface tension of samples (2.5 mg / L)

[0040] sample Surface tension (mN / m) Example 1 49.83 Example 2 48.71 Example 3 47.45 Example 4 46.81 Example 5 47.47 Solids after drying of pulping black liquor 64.84

[0041] *The surface tension of deionized water is 72.81 mN / m.

Claims

1. A method for preparing lignin amine cationic surfactant by high-value aqueous phase of papermaking by-product black liquor, characterized in that: The following steps are involved: Take an appropriate amount of pulping black liquor, adjust the pH of the pulping black liquor to a certain range with acid or alkali, centrifuge to take the supernatant, add an appropriate amount of epichlorohydrin, heat to a certain temperature and react for 30 minutes. Then add an appropriate amount of amine reagent, react for a certain time, cool, centrifuge, and dry the solid precipitate to obtain the lignin amine cationic surfactant.

2. The method for preparing lignin amine cationic surfactant by high-value aqueous phase of papermaking by-product black liquor according to claim 1, characterized in that: The pH of the pulping black liquor is adjusted to 8-13 with acid or alkali. The acid can be an inorganic acid such as hydrochloric acid, phosphoric acid, sulfuric acid, or an organic acid such as formic acid, acetic acid, or a combination of several of them.

3. The method for preparing lignin amine cationic surfactant by high-value aqueous phase of papermaking by-product black liquor according to claim 1, characterized in that: The amount of epichlorohydrin added is 1.0-10.0 times the hydroxyl group contained in the lignin in the papermaking by-product black liquor, based on the molar ratio.

4. The method for preparing lignin amine cationic surfactant by high-value aqueous phase of papermaking by-product black liquor according to claim 1, characterized in that: The reaction temperature is 40-100°C.

5. The method for preparing lignin amine cationic surfactant by high-value aqueous phase of papermaking by-product black liquor according to claim 1, characterized in that: The amount of amine reagent added is 1.0-10.0 times the hydroxyl group contained in lignin in papermaking black liquor, based on the molar ratio; the amine reagent can be one or a combination of n-butylamine, n-propylamine, cardanol modified amine, etc.

6. The method for preparing lignin amine cationic surfactant by high-value aqueous phase of papermaking by-product black liquor according to claim 1, characterized in that: The reaction time is 10-300min.

7. The method for preparing lignin amine cationic surfactant by high-value aqueous phase of papermaking by-product black liquor according to claim 1, characterized in that: After centrifugation and washing, the lower precipitate is dried to obtain the lignin amine cationic surfactant.

8. The use of the lignin amine cationic surfactant as described in claims 1-7, characterized in that: The lignin amine cationic surfactant can be applied to the fields of softeners for textiles, antistatic agents, oil emulsifiers, bactericides and disinfectants.

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