Preparation method of bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue

Abstract

This invention relates to the field of dust pollution control materials technology, and discloses a method for preparing a bio-based composite dust suppressant based on modified hemicellulose from traditional Chinese medicine residue. The method includes: removing impurities, washing, drying, pulverizing, and sieving the traditional Chinese medicine residue to obtain powdered raw material; mixing it with an alkaline solution to extract hemicellulose, and separating and purifying it to obtain medicinal hemicellulose; then subjecting it to alkali activation and carboxymethylation reactions to obtain modified medicinal hemicellulose; compounding it with natural polysaccharides, plant-derived wetting agents, and moisture to obtain a bio-based composite dust suppressant mother liquor; adjusting the dilution ratio and spraying amount according to the dust source particle size, moisture content, and disturbance intensity to form a wetting, penetrating, particle-adhesive, and continuous dust suppressant film on the dust source surface. This invention realizes the resource utilization of traditional Chinese medicine residue and improves the dispersion stability, film-forming properties, and long-lasting dust suppressant effect.

Description

Technical Field

[0001] This invention relates to the field of dust pollution control materials technology, and in particular to a method for preparing a bio-based composite dust suppressant based on modified hemicellulose from traditional Chinese medicine residue. Background Technology

[0002] In scenarios such as coal transportation, construction, mining, municipal roads, and material storage yards, dust particles are easily resuspended due to wind disturbance, vehicle crushing, mechanical operations, and loading / unloading impacts, resulting in persistent dust pollution. Existing dust control methods typically include water spraying, covering and shielding, spraying chemical dust suppressants, and laying dust nets. Among these, water spraying is simple to operate, but the water evaporates quickly and has a short retention time in high-temperature, dry, or strong-wind environments, requiring frequent respraying. Covering and shielding are suitable for fixed storage yards, but their adaptability to transport roads, bare construction soil, and dynamic work areas is limited. Although ordinary chemical dust suppressants can improve dust binding for a certain period of time, their raw materials mostly rely on inorganic salts, petroleum-based polymers, or ordinary chemical binders, which can lead to problems such as insufficient degradation, soil residue risks, and insufficient environmental friendliness with long-term use.

[0003] To improve the environmental friendliness of dust suppression materials, bio-based dust suppressants using natural polymers such as starch, cellulose, plant gums, and polysaccharides as base components have emerged in existing technologies. These materials have a certain degree of renewability and biodegradability, which can reduce the potential environmental impact of traditional chemical dust suppressants. However, when natural polymers are used directly for dust suppression, they often suffer from problems such as unstable dispersion in the aqueous phase, easy agglomeration or settling during spraying, insufficient spreadability on the surface of dust particles, and limited film strength after drying. Especially in high-disturbance scenarios such as coal transportation, mining roads, and construction, dust suppressants not only need to wet the dust surface but also need to penetrate into the gaps between dust particles to connect loose dust particles and form a continuous and resilient covering film after the moisture evaporates. Relying solely on ordinary natural polymers usually makes it difficult to simultaneously meet the requirements of wetting and penetration, particle adhesion, surface film formation, and disturbance resistance.

[0004] On the other hand, a large amount of medicinal residue is generated during the production and extraction of traditional Chinese medicine. This residue contains components such as hemicellulose, cellulose, polysaccharides, and plant tissue residues. Among these, hemicellulose has certain hydrophilicity and film-forming potential. However, in current utilization methods, medicinal residue is usually treated as waste and disposed of through dumping, landfilling, incineration, or low-value treatment. The usable components, such as hemicellulose, are not fully converted into materials with clear dust suppression functions. If medicinal residue powder or ordinary extracts are directly added to dust suppressants, it is still difficult to solve the problems of poor dispersibility, uneven film formation, insufficient spraying stability, and limited on-site retention time.

[0005] Therefore, the key to developing green dust suppression materials is not just finding a biodegradable raw material, but rather effectively extracting hemicellulose from medicinal herb residues and modifying it appropriately to improve its aqueous dispersibility, dust particle adsorption capacity, and film-forming properties. Simultaneously, it is necessary to form a stable compound system with modified hemicellulose, natural polysaccharides, and plant-derived wetting factors, allowing the spray liquid to first wet and penetrate the gaps between dust particles, then adhere to adjacent dust particles, and finally form a continuous dust suppression film after water evaporation. Only in this way can bio-based dust suppressants achieve a balance of environmental friendliness, spray applicability, and long-lasting dust suppression effect in actual dusty environments.

[0006] In summary, the core problem of existing technologies lies in how to stably extract hemicellulose from low-value solid waste and functionalize it so that it can form a composite dust suppression system that is sprayable, permeable, adhesive, film-forming, and easily degradable with natural polysaccharides and plant-derived wetting factors. This would enable more stable and long-lasting dust suppression in actual dust-generating scenarios such as coal transportation, construction, mining, and municipal roads. Summary of the Invention

[0007] To overcome the aforementioned deficiencies in the prior art, embodiments of the present invention provide a method for preparing a bio-based composite dust suppressant based on modified hemicellulose from traditional Chinese medicine residue. This method involves alkaline extraction and carboxymethylation of hemicellulose from traditional Chinese medicine residue, followed by staged compounding of the modified medicinal hemicellulose with natural polysaccharides and plant-derived wetting factors. The resulting dust suppressant sequentially undergoes wetting and penetration, particle adhesion, and continuous film formation on the dust source surface. This addresses the problems mentioned in the background art, such as insufficient utilization of hemicellulose from traditional Chinese medicine residue, poor dispersibility of ordinary bio-based dust suppressants, uneven film formation, and insufficient long-term dust suppression stability. The method achieves a synergistic improvement in the resource utilization of traditional Chinese medicine residue and green, degradable, and long-term dust suppression in complex dust environments.

[0008] To achieve the above objectives, the invention provides a method for preparing a bio-based composite dust suppressant based on hemicellulose modified from traditional Chinese medicine residue, comprising the following steps: S1. Pretreatment of Chinese medicinal residue raw materials The raw material of Chinese medicinal residue is subjected to impurity removal, washing, drying, crushing and screening to remove sand and gravel impurities, residual packaging materials, metal fragments and insoluble hard impurities from the Chinese medicinal residue, so as to obtain Chinese medicinal residue powder raw material with particle size and moisture content that meet the requirements of subsequent alkali extraction.

[0009] Specifically, the raw material of Chinese herbal medicine residue is first spread out and manually or mechanically removed to remove visible sand, plastic, packaging residue and hard impurities. Then, the residue is rinsed with clean water to remove surface mud and soluble impurities. Subsequently, it is dried at 50℃-80℃ to control the moisture content of the residue to 8%-15%. The dried residue is then crushed and sieved through a 40-80 mesh screen. The material that passes through the screen is returned to the crushing step for reprocessing, while the material that passes through the screen is used as the raw material of Chinese herbal medicine residue powder for subsequent alkali extraction.

[0010] Through the above treatment, the raw materials of Chinese herbal medicine residue have a relatively stable particle size distribution and moisture content before entering the alkali extraction process. This avoids the problem that the raw material particles are too large, making it difficult for the alkali solution to penetrate into the fiber structure. It also avoids that the moisture content fluctuations will affect the material-liquid ratio and the dissolution efficiency of hemicellulose.

[0011] S2, Extraction of hemicellulose alkali from medicinal sources The raw material of Chinese herbal medicine residue powder is mixed with alkaline solution according to a preset material-liquid ratio. Alkaline extraction is carried out under stirring and heating conditions to dissolve the hemicellulose in the raw material of Chinese herbal medicine residue powder from the fiber structure of the residue. After solid-liquid separation, an alkaline extract containing medicinal hemicellulose is obtained.

[0012] Specifically, the alkaline solution is a sodium hydroxide solution, a potassium hydroxide solution, or a mixture of the two, with a mass concentration of 2%-10%. The raw material of Chinese herbal medicine residue powder is mixed with the alkaline solution at a mass-volume ratio of 1:8-1:25, and stirred and extracted at 50℃-90℃ for 1-5 hours. This causes the cell walls and fiber structure of the Chinese herbal medicine residue to swell with alkali, which promotes the release of hemicellulose components from cellulose, lignin, and other insoluble residues.

[0013] After extraction, insoluble residues are separated by filtration or centrifugation, and the filtrate or centrifugal supernatant is collected as an alkaline extract containing the drug-derived hemicellulose. The insoluble residues can be washed and further processed for resource recovery to avoid direct discharge and secondary pollution.

[0014] This step transforms the hemicellulose components in traditional Chinese medicine residues, which are difficult to use directly in the preparation of dust suppressants, into liquid-phase hemicellulose resources that can be further separated, purified, and modified, providing a raw material basis for subsequent carboxymethylation modification.

[0015] S3. Separation and purification of drug-derived hemicellulose The alkaline extract containing medicinal hemicellulose was subjected to pH adjustment, precipitation separation, washing and drying to remove residual alkali, soluble small molecule impurities and free salts, thus obtaining medicinal hemicellulose.

[0016] Specifically, the alkaline extract is adjusted to neutral or weakly acidic using an acid solution to gradually lower the pH of the system and avoid strong alkali residue affecting subsequent modification reactions. Then, ethanol is added to the adjusted extract to precipitate the drug-derived hemicellulose from the liquid phase system. The precipitate is then collected by filtration or centrifugation and washed sequentially with an ethanol aqueous solution and deionized water until the washing solution is close to neutral. Finally, it is dried at 40℃-70℃ to obtain the drug-derived hemicellulose.

[0017] This step separates the drug-derived hemicellulose from the liquid phase in the alkaline extract and reduces the impact of residual alkali, salts, and low-molecular-weight impurities on the stability of the carboxymethylation reaction, resulting in drug-derived hemicellulose with better reaction controllability and consistency in subsequent compounding.

[0018] S4, Carboxymethylation modification of drug-derived hemicellulose The drug-derived hemicellulose was dispersed in a reaction medium and then subjected to alkalization activation and carboxymethylation reactions in sequence, so that the carboxymethyl groups were attached to the drug-derived hemicellulose molecular chain. After the reaction was completed, the drug-derived hemicellulose was obtained by neutralization, washing and drying.

[0019] Specifically, the drug-derived hemicellulose is added to an ethanol-water system or an isopropanol-water system and stirred to disperse. An alkalizing agent is added for alkalization and activation, so that the hydroxyl groups on the drug-derived hemicellulose molecular chain are in an activated state that is more likely to undergo etherification. Then, chloroacetic acid or sodium chloroacetate is added as a carboxymethylating agent, and the reaction is carried out at 45℃-75℃ for 1h-4h, so that the carboxymethyl groups are attached to the drug-derived hemicellulose molecular chain. After the reaction is completed, the reaction system is adjusted to neutral, and the modified drug-derived hemicellulose is obtained by washing, filtering and drying.

[0020] In this step, by controlling the feeding ratio of drug-derived hemicellulose, alkalizing agent and carboxymethylating agent, as well as controlling the reaction temperature and reaction time, the resulting modified drug-derived hemicellulose can simultaneously meet the requirements of aqueous phase dispersion performance and spray film formation performance.

[0021] Furthermore, to improve the adjustability and feasibility of the modification process, this invention establishes the following modification degree feedback control rules: When the modified drug-derived hemicellulose is made into a dispersion, and significant sedimentation occurs under static conditions, or when the height of the sedimentation layer exceeds 10% of the total liquid height after standing for 2 hours, it is judged that the degree of carboxymethylation or the dispersion ability of the aqueous phase is insufficient. In this case, the amount of carboxymethylation reagent, the carboxymethylation reaction time, or the reaction temperature can be increased to improve the degree of carboxymethyl group incorporation. When the apparent viscosity of the modified drug-derived hemicellulose dispersion is too high, resulting in uneven atomization, nozzle blockage, or spraying time per unit volume exceeding the preset spraying time when the sprayed liquid passes through the nozzle, it is determined that the degree of modification or the viscosity of the system is too high. The amount of carboxymethylation reagent, the carboxymethylation reaction time, or the amount of modified drug-derived hemicellulose added to the mother liquor should be reduced to ensure spray flowability. When the modified drug-derived hemicellulose dispersion shows no obvious stratification after standing, is continuously sprayed from the nozzle with uniform atomization, and can form a visible continuous wet cover layer on the surface of dust particles, it is judged to meet the requirements for subsequent compounding.

[0022] Through the above feedback regulation, carboxymethylation modification is no longer limited to a simple chemical modification step, but is directly related to the aqueous phase stability, spray applicability and film-forming properties of the final dust suppressant, thereby improving process stability and on-site feasibility.

[0023] S5, Bio-based Composite Dust Suppressant Mother Liquor Compound Modified drug-derived hemicellulose, natural polysaccharides, plant-derived wetting factors, and water were mixed in stages to obtain a bio-based composite dust suppressant mother liquor.

[0024] Specifically, by weight, the mother liquor of the bio-based composite dust suppressant includes: 1-8 parts of modified medicinal hemicellulose, 0.2-3 parts of natural polysaccharides, 0.05-1 parts of plant-derived wetting factor, and 88-98 parts of water; Natural polysaccharides are one or more of xanthan gum, guar gum, sodium alginate, chitosan, or starch derivatives. Plant-derived wetting factors are one or more of tea saponins, saponin extracts, alkyl glycosides, or plant-derived surfactants.

[0025] During compounding, the modified drug-derived hemicellulose is first added to a portion of water and stirred to swell and disperse, forming a modified hemicellulose dispersion. Then, the natural polysaccharide is pre-swollen and added to the modified hemicellulose dispersion for homogenization and mixing, so that the natural polysaccharide and the modified drug-derived hemicellulose form an intertwined and binding-enhancing system. Subsequently, plant-derived wetting factors and the remaining water are added, and stirring is continued until there are no obvious agglomerated particles in the system. Finally, after filtration and settling to defoam, the bio-based composite dust suppressant mother liquor is obtained.

[0026] In the aforementioned compound system, modified pharmaceutical hemicellulose serves as the main bio-based film-forming framework, providing dust particle adsorption, particle bonding, and drying film-forming capabilities. Natural polysaccharides enhance the system's bonding strength and film toughness, reducing film brittleness after drying. Plant-derived wetting factors reduce the contact resistance between the spray liquid and the dust particle surface, improving the spray liquid's wetting and penetration capabilities on the dust surface and between dust particles. Customer documentation clearly states that this dust suppressant uses modified pharmaceutical hemicellulose as the matrix, supplemented with natural polysaccharides and plant-derived wetting factors, ultimately producing a novel, green, and easily degradable dust suppressant.

[0027] By compounding in stages, we can avoid the aggregation caused by the direct addition of natural polysaccharides, and also avoid the premature addition of plant-derived wetting factors that would affect the full swelling of modified hemicellulose, thereby improving the uniformity of the mother liquor, storage stability and consistency of on-site spraying.

[0028] S6, scenario-based dilution, spraying, and film-forming dust fixation Based on the dust particle size, surface moisture content, and external disturbance intensity of the target dust source, the mother liquor of the bio-based composite dust suppressant is diluted and the spraying parameters are adjusted. The adjusted bio-based composite dust suppressant is then sprayed onto the surface of the dust source, allowing it to penetrate and spread along the surface and gaps between dust particles, and form a continuous dust suppressant film covering the surface of the dust source after the moisture evaporates.

[0029] Specifically, before spraying, the target dust source should be assessed or detected on-site: Dust particle size is obtained through on-site sieving, particle size analyzer, or sampling analysis. Surface moisture content was obtained by a portable moisture meter, sampling and weighing drying method, or on-site empirical calibration. The intensity of external disturbances is determined based on wind speed, vehicle traffic frequency, mechanical operation frequency, loading and unloading disturbance intensity, or rainwater erosion risk.

[0030] When the dust particles are small, the surface moisture content is low, or the intensity of external disturbance is high, increase the mass ratio of the bio-based composite dust suppressant mother liquor in the spray liquid, or increase the spraying amount per unit area, so that the spray liquid has stronger wetting penetration and particle adhesion ability. When the dust particles are large, the surface moisture content is high, or the intensity of external disturbance is low, reduce the mass ratio of the bio-based composite dust suppressant mother liquor in the spray liquid, or reduce the spraying amount per unit area, so that the spray liquid remains permeable, spreadable, and does not produce obvious dripping on the surface of the target dust source.

[0031] After spraying, the bio-based composite dust suppressant sequentially forms three stages on the dust source surface: wetting and penetration, particle adhesion, and surface film formation. During the wetting and penetration stage, plant-derived wetting factors reduce the contact resistance between the spray liquid and the surface of dust particles, allowing the spray liquid to enter the gaps between dust particles. During the particle bonding stage, modified drug-derived hemicellulose and natural polysaccharides adhere together to the surface of dust particles and connect adjacent dust particles, causing loose dust particles to gradually form a solidified structure. During the surface film-forming stage, as moisture evaporates, the modified drug-derived hemicellulose and natural polysaccharides form a continuous dust-suppressing film covering the surface of the dust source, thereby reducing the probability of dust particles being re-raised under conditions of wind disturbance, vehicle crushing, mechanical operation, or rain rinsing.

[0032] Through this step, the present invention establishes a correspondence between the laboratory-prepared bio-based composite dust suppressant and actual dust control scenarios, enabling the dust suppressant to be adjusted in dilution ratio and spraying amount for different dust source conditions such as coal transportation, construction, mining, and municipal roads. Customer data also clearly states that this dust suppressant is mainly suitable for environments such as coal transportation, construction, and mining, and has good dust suppression efficiency, dust suppression cycle, biodegradability, and environmental adaptability.

[0033] Based on the above technical solution, the present invention can also adopt the following preferred embodiments: First, the preferred medicinal residue is plant-based residue generated during the decoction, extraction, or pharmaceutical production of traditional Chinese medicine. This type of residue contains hemicellulose, polysaccharides, cellulose, and some plant tissue residues, making it suitable as a resource-based raw material for bio-based dust suppression materials. Customer data indicates that the hemicellulose content in the medicinal residue is 18%-28%, providing a material basis for subsequent extraction of hemicellulose from the medicinal source.

[0034] Secondly, if the extract is too dark in color, contains too many impurities, or the filtrate is turbid after solid-liquid separation during alkaline extraction, coarse filtration, static sedimentation, or decolorization treatment can be added before S3 to reduce the impact of impurities on hemicellulose precipitation and subsequent carboxymethylation reaction.

[0035] Third, during the carboxymethylation modification process, if the obtained modified drug-derived hemicellulose is used in low-temperature environment construction, the degree of carboxymethylation can be appropriately increased to enhance its aqueous phase dispersibility; if it is used in high-disturbance, high-compression coal transportation or mining road scenarios, the ratio of modified drug-derived hemicellulose and natural polysaccharides can be appropriately increased to enhance the adhesion strength and wear resistance of the dried film layer.

[0036] Fourth, in the compounding process, the natural polysaccharide is preferably one or more of xanthan gum, guar gum or sodium alginate to improve the viscosity stability of the system and the toughness of the dry film; the plant-derived wetting factor is preferably one or more of tea saponin, saponin extract or alkyl glycoside to improve the wetting and diffusion ability of dust particles.

[0037] Fifth, during on-site spraying, different spraying strategies can be adopted according to the actual dust source scenario: for bare soil surfaces during construction, priority should be given to controlling the uniformity of the sprayed liquid and the continuity of the surface film; for coal transport surfaces, priority should be given to controlling the penetration of the sprayed liquid into the gaps between coal dust particles and the ability to resist transport disturbance; for mining road surfaces, priority should be given to controlling the spraying amount per unit area and the strength of the film layer against rolling; for municipal roads or stockpile surfaces, priority should be given to controlling the spraying to prevent dripping, liquid accumulation, and the formation of a stable covering film layer.

[0038] The technical effects and advantages of this invention are as follows: Compared with the prior art, the present invention has at least the following beneficial effects: 1. This invention uses Chinese medicinal herb residue as raw material, obtains medicinal hemicellulose through alkali extraction, and further obtains modified medicinal hemicellulose through carboxymethylation modification, transforming the originally low-value-treated Chinese medicinal herb residue solid waste into a dust suppressant matrix with aqueous dispersibility, particle adsorption and film-forming ability, thus realizing the combination of resource utilization of Chinese medicinal herb residue and dust control.

[0039] 2. This invention does not directly add Chinese herbal medicine residue powder to the dust suppressant. Instead, it first pre-treats, extracts and separates the Chinese herbal medicine residue, and then modifies it with carboxymethylation. This releases hemicellulose from the original fiber structure of the residue and forms a controllable modified functional bio-based material, which significantly improves the stability of raw material utilization and the repeatability of the technical solution.

[0040] 3. This invention introduces hydrophilic carboxymethyl groups into the molecular chain of drug-derived hemicellulose through carboxymethylation modification, which improves the dispersion stability of drug-derived hemicellulose in the aqueous system and enhances its wetting and adsorption capacity on the surface of dust particles. This enables it to participate in the formation of a continuous dust-suppressing film after spraying, avoiding the problems of poor dispersibility, easy sedimentation, and uneven film formation of unmodified hemicellulose.

[0041] 4. This invention establishes a feedback control relationship between the degree of carboxymethylation and dispersion stability and spray flowability. When significant sedimentation occurs in the dispersion, the dispersibility can be improved by increasing the amount of carboxymethylation reagent or extending the reaction time. When the viscosity of the system is too high and affects spraying, the flowability can be improved by reducing the amount of reagent, shortening the reaction time, or adjusting the amount added. This directly links the modification step with the final spraying application, enhancing the operability and creativity of the preparation method.

[0042] 5. This invention combines modified medicinal hemicellulose, natural polysaccharides, and plant-derived wetting factors in stages, so that the modified medicinal hemicellulose provides a bio-based film-forming framework, the natural polysaccharides improve the bonding strength and film toughness, and the plant-derived wetting factors improve the wetting and penetration ability of dust particles, thereby forming a continuous dust suppression chain of "wetting and penetration - particle bonding - surface film formation".

[0043] 6. In the compounding process, the present invention adopts a phased process of first swelling and dispersing the modified drug-derived hemicellulose, then adding pre-swollen natural polysaccharides, and finally adding plant-derived wetting factors and the remaining water. This reduces the problems of agglomeration, stratification and uneven spraying during the compounding process, and improves the uniformity of the dust suppressant mother liquor and the stability of on-site construction.

[0044] 7. This invention adjusts the dilution ratio and spraying amount according to the dust particle size, surface moisture content and external disturbance intensity, so that the bio-based composite dust suppressant can adapt to different dust source conditions such as construction, coal transportation, mining, and municipal roads, instead of using a fixed concentration and fixed spraying amount for simple treatment, thus improving the scene adaptability of the dust suppressant.

[0045] 8. The dust suppressant sprayed by this invention can sequentially form a wetting and penetrating layer, a particle bonding layer and a continuous covering film layer on the surface of the dust source, which can reduce the probability of dust being re-raised under conditions of wind disturbance, vehicle crushing, mechanical operation and rain washing, and help to prolong the dust suppression time.

[0046] 9. This invention uses bio-based materials as the main body, combined with natural polysaccharides and plant-derived wetting factors, which reduces the environmental residue risks that may be caused by long-term use of traditional inorganic salts, petroleum-based polymers or strong chemical binders, and has good green degradation and eco-friendly characteristics. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the steps in preparing a bio-based composite dust suppressant based on modified hemicellulose from Chinese medicinal herb residue according to the present invention. Detailed Implementation

[0048] The present invention will be further described below with reference to embodiments. It should be understood that the following embodiments are used to explain the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, equivalent substitutions made to the source of raw materials, equipment form, reaction vessel, mixing method, spraying equipment, or detection method without departing from the technical concept of the present invention should all fall within the scope of protection of the present invention.

[0049] This invention provides a method for preparing a bio-based composite dust suppressant based on modified hemicellulose from traditional Chinese medicine residue. The method uses traditional Chinese medicine residue as raw material, and sequentially involves pretreatment of the residue, alkaline extraction of hemicellulose, separation and purification of the medicinal hemicellulose, carboxymethylation modification, formulation of a bio-based composite dust suppressant mother liquor, and on-site dilution and spraying to form a film. This yields a bio-based composite dust suppressant capable of wetting and penetrating the dust source surface, particle adhesion, and continuous film formation.

[0050] Example 1: Overall Preparation Method Reference Figure 1 This embodiment provides a method for preparing a bio-based composite dust suppressant based on modified hemicellulose from traditional Chinese medicine residue, including the following steps.

[0051] S1. Pretreatment of Chinese medicinal residue raw materials Take the plant-based Chinese medicine residue generated during the decoction, extraction, or pharmaceutical production of Chinese medicinal herbs as raw materials; spread the Chinese medicine residue raw materials on a clean processing platform and remove sand, plastic residue, metal fragments, residual packaging materials, and insoluble hard impurities; after removing impurities, rinse the Chinese medicine residue with clean water to remove the mud and sand attached to the surface and some soluble impurities.

[0052] After rinsing, the Chinese herbal medicine residue is placed in a hot air drying device and dried at 50℃-80℃ to control the moisture content of the residue to 8%-15%. The dried residue is then pulverized in a crushing device and sieved through a 40-80 mesh screen. The material under the screen is used as the raw material for Chinese herbal medicine residue powder, while the material over the screen is returned to the crushing device for re-crushing.

[0053] This step ensures that the raw materials of Chinese herbal medicine residue powder entering the subsequent alkali extraction step have a relatively stable particle size distribution and moisture content. When the particle size is too large, the alkali solution cannot easily penetrate into the interior of the fiber structure of the residue, and the hemicellulose dissolution efficiency decreases. When the moisture content is too high, adhesion and clumping are likely to occur during the crushing and sieving process. When the moisture content is too low, the raw materials are likely to form excessively fine powder and increase the filtration load. Therefore, controlling the moisture content at 8%-15% and the particle size at 40-80 mesh is beneficial to improving the stability of the subsequent alkali extraction process.

[0054] S2, Extraction of hemicellulose alkali from medicinal sources The Chinese herbal residue powder obtained in S1 is added to the reaction vessel along with the alkaline solution according to a preset material-to-liquid ratio; the alkaline solution is a sodium hydroxide solution, a potassium hydroxide solution, or a mixture of the two, and the mass concentration of the alkaline solution is 2%-10%; preferably, the mass-to-volume ratio of the Chinese herbal residue powder to the alkaline solution is 1:8-1:25.

[0055] The reaction system was stirred and extracted at 50℃-90℃ for 1h-5h. During the stirring process, the alkali solution penetrated into the interior of the Chinese herbal medicine residue powder, causing the fiber structure of the residue to swell with alkali, which promoted the release of hemicellulose from cellulose, lignin and other insoluble components and into the liquid phase.

[0056] After extraction, the reaction system is subjected to solid-liquid separation. Solid-liquid separation can be performed by filtration, centrifugation, plate and frame filtration, or vacuum filtration; collect the filtrate or centrifugal supernatant to obtain an alkaline extract containing drug-derived hemicellulose; the insoluble residue can be further processed after washing.

[0057] S3. Separation and purification of drug-derived hemicellulose Place the alkaline extract containing drug-derived hemicellulose obtained from S2 into a stirred container, and slowly add acid solution under stirring conditions to adjust the pH of the system to neutral or weakly acidic; the acid solution can be hydrochloric acid, acetic acid, citric acid or other acid solutions that can achieve pH adjustment; during the adjustment process, avoid adding a large amount of acid solution at one time to prevent local acidity from being too high and affecting the uniformity of precipitation.

[0058] After pH adjustment, ethanol is added to the adjusted extract to precipitate the drug-derived hemicellulose from the liquid phase system. Stirring continues after adding ethanol to ensure thorough mixing, followed by standing until precipitation occurs. Once precipitate has formed, it is collected by filtration or centrifugation.

[0059] The collected precipitate was first washed with an ethanol-water solution to remove some soluble small molecules, pigments and free impurities; then washed with deionized water until the washing solution was nearly neutral; after washing, it was dried at 40℃-70℃ to obtain the drug-derived hemicellulose.

[0060] This step removes residual alkali, free salts, and soluble small molecule impurities, giving the resulting drug-derived hemicellulose better stability for subsequent modification reactions.

[0061] S4, Carboxymethylation modification of drug-derived hemicellulose The drug-derived hemicellulose obtained from S3 is added to an ethanol-water system or an isopropanol-water system and dispersed under stirring to ensure thorough wetting of the drug-derived hemicellulose. Subsequently, an alkalizing agent is added for alkalization and activation, activating the hydroxyl groups on the drug-derived hemicellulose molecular chains; the alkalizing agent can be sodium hydroxide, potassium hydroxide, or a mixture of both.

[0062] After alkalization and activation, chloroacetic acid or sodium chloroacetate is added as a carboxymethylation reagent, and the reaction is carried out at 45℃-75℃ for 1h-4h to allow the carboxymethyl groups to be attached to the drug-derived hemicellulose molecular chain. After the reaction is completed, the reaction system is adjusted to neutral, and the product is washed, filtered and dried to obtain modified drug-derived hemicellulose.

[0063] In this step, the degree of carboxymethylation modification is controlled by the feeding ratio of drug-derived hemicellulose, alkalizing agent, and carboxymethylation reagent, as well as the reaction temperature and reaction time. If the degree of modification is insufficient, the modified drug-derived hemicellulose is prone to sedimentation in the aqueous phase, resulting in poor stability of the subsequent spray solution. If the degree of modification is too high or the viscosity of the system is too high, uneven atomization, nozzle clogging, or insufficient spray flow are likely to occur during the spraying process. Therefore, this step combines the carboxymethylation reaction with the subsequent aqueous phase dispersibility and spray film-forming performance for control.

[0064] S5, Bio-based Composite Dust Suppressant Mother Liquor Compound The modified drug-derived hemicellulose, natural polysaccharides, plant-derived wetting factors, and water obtained from S4 were mixed in stages to obtain the mother liquor of the bio-based composite dust suppressant.

[0065] By weight, the mother liquor of the bio-based composite dust suppressant includes: 1-8 parts of modified medicinal hemicellulose, 0.2-3 parts of natural polysaccharides, 0.05-1 parts of plant-derived wetting factor, and 88-98 parts of water.

[0066] The natural polysaccharide is one or more of xanthan gum, guar gum, sodium alginate, chitosan, or starch derivatives; the plant-derived wetting factor is one or more of tea saponin, saponin extracts, alkyl glycosides, or plant-derived surfactants.

[0067] During compounding, the modified drug-derived hemicellulose is first added to a portion of water and stirred to swell, forming a modified hemicellulose dispersion. Then, the natural polysaccharide is pre-swollen and added to the modified hemicellulose dispersion for homogenization and mixing, so that the natural polysaccharide and the modified drug-derived hemicellulose form an interwoven and binding-enhancing system. Finally, plant-derived wetting factor and the remaining water are added, and stirring is continued until there are no obvious agglomerated particles in the system. After filtration and standing to defoam, the bio-based composite dust suppressant mother liquor is obtained.

[0068] By adopting the above-mentioned staged compounding method, the aggregation phenomenon caused by the direct addition of natural polysaccharides can be reduced, and the premature addition of plant-derived wetting factors can be avoided from affecting the full swelling of modified drug-derived hemicellulose, so that the resulting mother liquor has better uniformity and spraying stability.

[0069] S6. On-site dilution, spraying, and film-forming dust fixation. The bio-based composite dust suppressant mother liquor obtained from S5 is diluted and spraying parameters are adjusted according to the dust particle size, surface moisture content and external disturbance intensity of the target dust source. After the adjusted bio-based composite dust suppressant is sprayed onto the surface of the dust source, it penetrates and spreads along the surface and gaps between dust particles, and forms a continuous dust suppressant film covering the surface of the dust source after the moisture evaporates.

[0070] Before spraying, collect the dust particle size, surface moisture content, and external disturbance intensity of the target dust source. The dust particle size can be obtained through on-site sieving, particle size analyzer, or sampling analysis. The surface moisture content can be obtained through portable moisture meter, sampling weighing and drying method, or on-site empirical calibration. The external disturbance intensity can be determined based on wind speed, vehicle traffic frequency, mechanical operation frequency, loading and unloading disturbance intensity, or rainwater erosion risk.

[0071] When the dust particles are small, the surface moisture content is low, or the intensity of external disturbance is high, the mass ratio of the bio-based composite dust suppressant mother liquor in the spray liquid should be increased, or the spraying amount per unit area should be increased. At this time, the spray liquid needs to have stronger wetting and penetrating ability and particle adhesion ability to adapt to fine dust particles and highly disturbed environments.

[0072] When the dust particles are large, the surface moisture content is high, or the intensity of external disturbance is low, reduce the mass ratio of the bio-based composite dust suppressant mother liquor in the spray liquid, or reduce the spraying amount per unit area; at this time, avoid the spray liquid from producing obvious drips, accumulations, or stickiness on the surface of the dust source.

[0073] After spraying, the bio-based composite dust suppressant sequentially forms a wetting and penetration stage, a particle bonding stage, and a surface film-forming stage. In the wetting and penetration stage, plant-derived wetting factors reduce the contact resistance between the spray liquid and the dust particle surface, allowing the spray liquid to enter the gaps between dust particles. In the particle bonding stage, modified drug-derived hemicellulose and natural polysaccharides adhere to the dust particle surface and connect adjacent dust particles. In the surface film-forming stage, as water evaporates, a continuous dust suppressant film layer is formed covering the surface of the dust source, thereby inhibiting the dust particles from being re-raised under conditions of wind disturbance, vehicle crushing, or rain erosion.

[0074] Example 2: Pretreatment and Alkali Extraction of Traditional Chinese Medicine Residue This embodiment further illustrates the pretreatment of Chinese medicinal residue and the extraction process of hemicellulose alkali.

[0075] Using plant-based Chinese medicinal herb residue as raw material, the residue is spread into a loose layer, and sand, metal fragments, plastic residue, and hard impurities are removed. After removal, it is rinsed with clean water 2-3 times until there is no obvious mud or sand in the rinse water. The rinsed residue is then placed in a hot air drying oven and dried at 60℃ to control its moisture content to 10%-12%.

[0076] The dried Chinese herbal medicine residue is added to a pulverizer and crushed, then sieved through a 60-mesh screen; the material that passes through the screen is crushed again, and the material that passes through the screen is collected as the Chinese herbal medicine residue powder raw material.

[0077] Take 100g of Chinese herbal medicine residue powder raw material, add 1500mL of 5% sodium hydroxide solution, and stir and extract at 70℃ for 3h. After extraction, centrifuge the reaction system to remove insoluble residue, collect the supernatant, and obtain an alkaline extract containing hemicellulose from the medicinal source.

[0078] In this embodiment, the Chinese herbal medicine residue powder is sieved through a 60-mesh screen to ensure that the alkali solution can fully penetrate the fiber structure of the residue; a 5% sodium hydroxide solution can cause the fiber structure of the residue to swell due to alkali; extraction at 70°C for 3 hours can balance the hemicellulose release efficiency and component stability.

[0079] Example 3: Isolation and purification of drug-derived hemicellulose Take the alkaline extract containing drug-derived hemicellulose obtained in Example 2, and slowly add dilute hydrochloric acid under stirring conditions to adjust the pH of the system to 6.5-7.0; keep stirring continuously during the adjustment process to ensure that the acid solution is evenly dispersed in the extract.

[0080] After pH adjustment, ethanol was added to the extract, and stirring was continued for 20-40 minutes to allow the hemicellulose to precipitate fully. The mixture was then allowed to stand until the precipitate stabilized. Once precipitate formed, it was collected by centrifugation.

[0081] The precipitate was first washed twice with an ethanol-water solution to remove some pigments and small molecule impurities; then washed with deionized water until the pH of the washing solution was close to neutral; after washing, the precipitate was placed in a drying device and dried at 50℃-60℃ to obtain the drug-derived hemicellulose.

[0082] In this embodiment, the drug-derived hemicellulose is separated from the alkaline extract through pH adjustment, ethanol precipitation, washing, and drying, and the impact of residual alkali and free impurities on subsequent carboxymethylation modification is reduced.

[0083] Example 4: Carboxymethylation Modification and Evaluation Regulation of Drug-Derived Hemicellulose This embodiment further illustrates the carboxymethylation modification process of drug-derived hemicellulose and its evaluation and control methods.

[0084] Take 10g of drug-derived hemicellulose and add it to an ethanol-water system. Stir and disperse for 30-60 minutes to fully wet the drug-derived hemicellulose. Then add sodium hydroxide for alkalization and activation to activate the hydroxyl groups on the drug-derived hemicellulose molecular chain. After alkalization and activation, add sodium chloroacetate as a carboxymethylation reagent and react at 60℃ for 2-3 hours. After the reaction is completed, adjust the reaction system to neutral, wash, filter and dry to obtain modified drug-derived hemicellulose.

[0085] To ensure that the modified hemicellulose source can support subsequent compounding and spraying, this embodiment includes evaluations of dispersion stability and sprayability.

[0086] Take 1g of modified hemicellulose and add it to 99g of water. Stir to form a 1% (w / w) modified hemicellulose dispersion. Place the dispersion in a transparent graduated cylinder and let it stand for 2 hours. Observe the sedimentation. When the height of the sedimentation layer exceeds 10% of the total liquid height after 2 hours of standing, it is determined that the aqueous phase dispersion ability of the modified hemicellulose is insufficient. In the next batch preparation, increase the amount of carboxymethylation reagent, extend the carboxymethylation reaction time, or appropriately increase the reaction temperature.

[0087] Take 100 mL of the above dispersion and spray it through a nozzle with an orifice diameter of 0.8 mm-1.5 mm. When the sprayed liquid is continuous, the atomization is uniform, and the nozzle is not blocked, the spraying passability is judged to be qualified. When the sprayed liquid is intermittent, the atomization is coarse, or the nozzle is blocked, the spraying passability is judged to be insufficient. In the next batch preparation, reduce the amount of carboxymethylation reagent, shorten the carboxymethylation reaction time, or reduce the amount of modified drug source hemicellulose added when compounding.

[0088] When the modified drug-derived hemicellulose dispersion shows no obvious stratification after standing, sprays continuously and atomizes evenly from the nozzle, and forms a uniform wet coating on the surface of dust particles, it is judged to meet the requirements for subsequent compounding.

[0089] By using the above evaluation and control methods, the carboxymethylation modification process can be correlated with the aqueous phase dispersion performance, spray flow performance and film-forming application performance, thereby improving the controllability of the preparation process.

[0090] Example 5: Low-viscosity sprayable composite dust suppressant mother liquor This embodiment provides a low-viscosity sprayable bio-based composite dust suppressant mother liquor, which is suitable for municipal roads, lightly dusty material storage yards, dust sources with high surface moisture content or low external disturbance intensity.

[0091] Based on mass, take 1.5 parts of modified drug-derived hemicellulose, 0.3 parts of natural polysaccharide, 0.08 parts of plant-derived wetting factor, and 98.12 parts of water; the natural polysaccharide can be xanthan gum or guar gum, and the plant-derived wetting factor can be tea saponin or alkyl glycoside.

[0092] During compounding, the modified hemicellulose source is first added to a portion of water and stirred to swell, forming a modified hemicellulose dispersion. Then, the natural polysaccharide is pre-swollen and added to the modified hemicellulose dispersion for homogenization. Subsequently, plant-derived wetting agents and the remaining water are added, and stirring is continued until there are no obvious agglomerated particles in the system. Finally, after filtration and settling to defoam, a low-viscosity sprayable bio-based composite dust suppressant mother liquor is obtained.

[0093] The mother liquor has low viscosity and good spray flow, making it suitable for low-disturbance or light dust scenarios. When using it, the amount sprayed per unit area can be reduced to avoid significant dripping or liquid accumulation on the surface of the dust source.

[0094] Example 6: Standard film-forming composite dust suppressant mother liquor This embodiment provides a standard film-forming bio-based composite dust suppressant mother liquor, suitable for bare soil in construction sites, general coal storage yards, or conventional material storage yards.

[0095] Based on mass, take 3 parts of modified drug-derived hemicellulose, 0.6 parts of natural polysaccharide, 0.2 parts of plant-derived wetting factor, and 96.2 parts of water; the natural polysaccharide is preferably xanthan gum, and the plant-derived wetting factor is preferably tea saponin.

[0096] During compounding, the modified drug-derived hemicellulose is first added to about 60 parts of water and stirred to swell, forming a modified hemicellulose dispersion. Separately, natural polysaccharides are added to an appropriate amount of water to pre-swell, forming a natural polysaccharide pre-dispersion. The natural polysaccharide pre-dispersion is slowly added to the modified hemicellulose dispersion and homogenized to ensure that the natural polysaccharides and modified drug-derived hemicellulose are fully intertwined. Then, plant-derived wetting factors and the remaining water are added, and stirring is continued until the system is homogeneous. After filtration and standing to defoam, a standard film-forming bio-based composite dust suppressant mother liquor is obtained.

[0097] This mother liquor can form a relatively uniform wet cover layer after spraying, and form a continuous dust-suppressing film layer after the water evaporates, making it suitable for conventional dust control scenarios.

[0098] Example 7: High-disturbance, wear-resistant composite dust suppressant mother liquor This embodiment provides a high-disturbance, wear-resistant bio-based composite dust suppressant mother liquor, which is suitable for dust sources such as mine roads, coal transportation, roads subjected to high-frequency vehicle traffic, or high-intensity mechanical operations.

[0099] Based on mass, take 6 parts of modified drug-derived hemicellulose, 1.5 parts of natural polysaccharide, 0.4 parts of plant-derived wetting factor, and 92.1 parts of water; the natural polysaccharide can be a mixture of xanthan gum and sodium alginate, or a mixture of xanthan gum and guar gum; the plant-derived wetting factor can be tea saponin, saponin extracts, or alkyl glycosides.

[0100] When compounding, the modified drug-derived hemicellulose is first added to a portion of water to fully swell and disperse; then, the natural polysaccharides are pre-swelled and added to the modified hemicellulose dispersion for homogenization and mixing to form a strong adhesive and reinforcing structure; finally, plant-derived wetting factors and the remaining water are added, stirred evenly, filtered, and allowed to stand to defoam, to obtain a high-disturbance, wear-resistant bio-based composite dust suppressant mother liquor.

[0101] The mother liquor contains a high content of modified drug-derived hemicellulose and natural polysaccharides. The film layer formed after drying has high adhesion strength and toughness, making it suitable for scenarios with strong vehicle crushing, mechanical disturbance, or wind disturbance.

[0102] Example 8: On-site spraying parameter level adjustment method This embodiment further explains the on-site dilution and spraying parameter adjustment methods.

[0103] Before field application, the target dust source should be detected or assessed. When the dust particle size is less than 75μm, the surface moisture content is less than 5%, the wind speed is greater than 5m / s, or the vehicle passage frequency is greater than 20 times / h, the dust source is judged to be a high dust risk or high disturbance scenario. For such scenarios, a bio-based composite dust suppressant spray liquid with a higher mass ratio should be used, or the spraying amount per unit area should be increased so that the spray liquid can fully wet the dust particles and penetrate into the gaps between the dust particles.

[0104] When the dust particle size is 75μm-150μm, the surface moisture content is 5%-10%, the wind speed is 3m / s-5m / s, or the vehicle traffic frequency is 5 times / h-20 times / h, the dust source is judged to be a medium dust risk scenario. For this type of scenario, a standard film-forming mother liquor is sprayed after appropriate dilution so that the sprayed liquid forms a uniform covering layer on the surface of the dust source.

[0105] When the dust particle size is greater than 150μm, the surface moisture content is higher than 10%, the wind speed is lower than 3m / s, and the vehicle passage frequency is lower than 5 times / h, the dust source is judged to be a low dust risk scenario. For this type of scenario, a low-viscosity sprayable mother liquor is used for spraying after dilution to reduce the spraying amount per unit area, so that the sprayed liquid can be spreadable and avoid obvious dripping and accumulation.

[0106] The above-mentioned particle size, moisture content, wind speed, and vehicle traffic frequency are the preferred selection criteria; in practical applications, they can be appropriately adjusted according to the type of material of the target dust source, the construction season, the spraying equipment, and environmental protection requirements.

[0107] Example 9: Application methods in different dust pollution scenarios This embodiment illustrates the application of the bio-based composite dust suppressant of the present invention in different scenarios.

[0108] I. Exposed Soil Scene During Building Construction For bare soil during construction, the dust sources are mostly dry, fine-grained soil and loose dust generated by construction disturbance. First, the surface moisture content of the bare soil is tested on-site, and the dust fineness and wind conditions are observed. When the surface moisture content of the bare soil is low, the dust particles are fine, and the wind is strong, a standard film-forming or high-disturbance, wear-resistant bio-based composite dust suppressant stock solution is diluted and evenly sprayed onto the bare soil surface.

[0109] During spraying, the spray solution should cover the surface of the bare soil and penetrate into the gaps between surface dust particles, avoiding the formation of significant liquid accumulation. After spraying, the spray solution first wets the surface dust of the bare soil, and then connects adjacent dust particles through modified drug-derived hemicellulose and natural polysaccharides. After the moisture evaporates, a continuous dust-suppressing film layer is formed covering the surface of the bare soil.

[0110] II. Coal Transportation Scenarios In coal transportation scenarios, the dust source is the coal dust particles generated on the surface of the coal pile and during transportation. Due to vibration, airflow impact and loading and unloading disturbances during transportation, the spray liquid needs to enter the gaps between coal dust particles and form a relatively stable particle bonding structure.

[0111] When applying, select either a standard film-forming type or a high-disturbance wear-resistant type mother liquor based on the coal dust particle size and the intensity of transport disturbance. When the coal dust particles are fine or the transport disturbance is strong, increase the mass ratio of the mother liquor in the spray liquid or increase the spraying amount per unit area. After spraying, the modified drug-derived hemicellulose and natural polysaccharides adhere to the surface of the coal dust particles and connect adjacent particles. After the water evaporates, a continuous covering film is formed.

[0112] III. Mine Road Scene For mining roads, dust sources are subject to repeated vehicle traffic and mechanical operations, resulting in high external disturbance intensity. Therefore, a high-disturbance, wear-resistant mother liquor is preferred for application. Before spraying, the road surface moisture content, vehicle traffic frequency, and dust particle size should be assessed. When vehicle traffic frequency is high or the surface dust is fine, the concentration of the spray solution and the spraying rate per unit area should be increased.

[0113] After spraying, the spray liquid enters the gaps between dust particles on the road surface, connects the loose dust particles, and forms a continuous dust suppression film with a certain degree of toughness on the road surface to reduce the re-dust caused by vehicle rolling and wind disturbance.

[0114] IV. Municipal roads or light storage yard scenarios For municipal roads or lightly polluted material storage yards, when the surface dust particles are large, the moisture content is high, or the external disturbance is low, a low-viscosity spray-type mother liquor can be used. When using it, reduce the mass ratio of the mother liquor in the spray liquid or reduce the spray amount per unit area to ensure that the spray liquid is evenly spread on the surface of the dust source and avoid dripping, accumulation, and excessive surface stickiness.

[0115] Example 10: Dust Suppression Process This embodiment illustrates the action process of the bio-based composite dust suppressant of the present invention after spraying.

[0116] After the sprayed liquid reaches the surface of the dust source, it first enters the wetting and penetration stage; the plant-derived wetting factor reduces the contact resistance between the sprayed liquid and the surface of the dust particles, allowing the sprayed liquid to spread quickly on the surface of the dust particles and enter the pores between the dust particles.

[0117] Then the particle bonding stage begins; the modified drug-derived hemicellulose is dispersed in the spray liquid, adheres to the surface of the wetted dust particles, and forms a particle connection structure together with the natural polysaccharide; this structure transforms the adjacent dust particles from a loose state to a relatively stable aggregated or consolidated state.

[0118] Finally, the surface film-forming stage begins; as moisture evaporates, modified drug-derived hemicellulose and natural polysaccharides form a continuous dust-suppressing film layer on the surface of the dust source; this dust-suppressing film layer covers the surface of the dust source and connects the surface dust particles, making it difficult for dust to be re-raised under conditions of wind, vehicle crushing, mechanical disturbance or rain rinsing.

[0119] Therefore, this invention utilizes the synergistic effect of plant-derived wetting factors, modified medicinal hemicellulose, and natural polysaccharides to form a continuous dust suppression process involving wetting and penetration, particle adhesion, and surface film formation.

[0120] Example 11: Performance Verification To verify the effectiveness of the bio-based composite dust suppressant of this invention, the following comparative experiment can be set up.

[0121] Dust samples of the same source, mass, and particle size range were sprayed with water, unmodified drug-derived hemicellulose dispersion, ordinary natural polysaccharide dust suppressant, and the bio-based composite dust suppressant of this invention, respectively. Each treatment group maintained the same spraying amount and was observed and tested under the same temperature, humidity, and wind speed conditions.

[0122] The test indicators include the spray liquid spreading time, the uniformity of surface coverage after spraying, the integrity of the film layer after drying, the amount of dust raised after wind disturbance, the retention of the film layer after rain rinsing, and the dust suppression effect over a certain period.

[0123] The water treatment group mainly relies on water for short-term dust suppression, but the dust suppression effect decreases rapidly after the water evaporates; unmodified drug-derived hemicellulose dispersions are prone to uneven dispersion, sedimentation, and uneven film formation; ordinary natural polysaccharide dust suppressants have a certain binding effect, but their wetting and penetration capabilities and adaptability to complex scenarios are insufficient; the bio-based composite dust suppressant of this invention uses carboxymethylated modified drug-derived hemicellulose as the film-forming framework, and is combined with natural polysaccharides and plant-derived wetting factors, which can form a more stable wetting, binding, and film-forming structure on the surface of dust sources.

[0124] In one embodiment, the obtained bio-based composite dust suppressant is a light milky yellow liquid with weak alkalinity; after on-site dust suppression testing, its PM10 dust suppression efficiency can reach no less than 82%; under normal environmental conditions, its dust suppression maintenance period can reach 7-10 days; after biodegradation testing, the biodegradation rate can reach no less than 98% after 7 days; the above test results are used to illustrate that the bio-based composite dust suppressant prepared by the present invention has good on-site dust suppression effect and environmental friendliness.

[0125] Example 12: Parameter Adjustment Rules In actual production and application, the sources of Chinese medicine residue, types of medicinal materials, extraction processes, and dust source scenarios may vary. Therefore, parameters can be adjusted within the scope defined by this invention.

[0126] When the particle size of the Chinese herbal medicine residue powder is too coarse, resulting in a low hemicellulose content in the alkaline extract, the fineness of the powder can be increased, or the alkaline extraction time can be appropriately extended.

[0127] When the viscosity of the alkaline extract is significantly low, indicating insufficient dissolution of hemicellulose, the concentration of the alkaline solution can be appropriately increased, the extraction time extended, or the extraction temperature increased. However, excessive alkalinity or excessively high temperature should be avoided to prevent hemicellulose degradation.

[0128] When significant sedimentation occurs in the modified drug-derived hemicellulose dispersion after standing, the amount of carboxymethylating reagent can be increased, the carboxymethylation reaction time can be extended, or the reaction temperature can be appropriately increased.

[0129] When the viscosity of the modified drug-derived hemicellulose dispersion is too high, causing discontinuous spraying, uneven atomization, or nozzle clogging, the amount of carboxymethylation reagent can be reduced, the carboxymethylation reaction time can be shortened, or the proportion of modified drug-derived hemicellulose added to the mother liquor can be reduced.

[0130] When the surface of the dust source is unevenly wetted after spraying, the amount of plant-derived wetting agent can be appropriately increased; when the film layer is brittle or has insufficient resistance to disturbance after drying, the amount of natural polysaccharides can be appropriately increased; when there is obvious dripping or liquid accumulation on the surface after spraying, the concentration of the spray solution or the amount of spray per unit area can be reduced.

[0131] By adjusting the above parameters, the preparation method of this invention can be adapted to different Chinese herbal medicine residue raw materials and different dust control scenarios, and ensure that the obtained bio-based composite dust suppressant has relatively stable aqueous phase dispersibility, spray applicability, wetting and penetration and film-forming dust-fixing ability.

[0132] In summary, the complete implementation logic of this invention is as follows: First, the raw material state of Chinese herbal medicine residue, which contains impurities, water, and uneven particle size, is transformed into Chinese herbal medicine residue powder raw material with controllable particle size and water content; then, hemicellulose is released from the fiber structure of the residue and enters the liquid phase through alkaline extraction; subsequently, medicinal hemicellulose is obtained through pH adjustment, ethanol precipitation, washing, and drying; then, the medicinal hemicellulose is modified by carboxymethylation to give it better aqueous phase dispersibility, dust particle adsorption capacity, and film-forming ability; then, the modified medicinal hemicellulose is compounded with natural polysaccharides, plant-derived wetting factors, and moisture to obtain a uniform and stable bio-based composite dust suppressant mother liquor; finally, the dilution ratio and spraying amount are adjusted according to the dust particle size, surface water content, and external disturbance intensity to form a composite dust suppressant structure with wetting penetration, particle adhesion, and continuous film formation on the dust source surface.

[0133] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a bio-based composite dust suppressant based on modified hemicellulose from traditional Chinese medicine residues, characterized in that: Includes the following steps: S1. The Chinese herbal medicine residue raw material is subjected to impurity removal, washing, drying, crushing and screening to remove sand and gravel impurities, residual packaging materials and insoluble hard impurities from the Chinese herbal medicine residue, so as to obtain Chinese herbal medicine residue powder raw material with particle size distribution that meets the requirements of alkali extraction. S2. Mix the Chinese herbal medicine residue powder raw material with alkaline solution according to the preset material-liquid ratio, and carry out alkaline extraction under stirring and heating conditions to dissolve the hemicellulose in the Chinese herbal medicine residue powder raw material from the fiber structure of the residue, and obtain an alkaline extract containing medicinal hemicellulose through solid-liquid separation. S3. The alkaline extract containing medicinal hemicellulose is subjected to pH adjustment, precipitation separation, washing and drying to remove residual alkaline solution, soluble small molecules and free impurities, and obtain medicinal hemicellulose. S4. The drug-derived hemicellulose is dispersed in the reaction medium and subjected to alkalization activation and carboxymethylation reactions in sequence, so that the carboxymethyl groups are attached to the drug-derived hemicellulose molecular chain. After the reaction is completed, it is neutralized, washed and dried to obtain modified drug-derived hemicellulose. S5. Modified drug-derived hemicellulose is mixed with natural polysaccharides, plant-derived wetting factors and water in stages to form an aqueous dispersion skeleton of modified drug-derived hemicellulose, and natural polysaccharides are intertwined with the aqueous dispersion skeleton to form a bonding and reinforcing system. Plant-derived wetting factors are dispersed in the bonding and reinforcing system to obtain a bio-based composite dust suppressant mother liquor. S6. Based on the dust particle size, surface moisture content and external disturbance intensity of the target dust source, dilute the mother liquor of the bio-based composite dust suppressant and adjust the spraying parameters. Spray the adjusted bio-based composite dust suppressant onto the surface of the dust source, allowing it to penetrate and spread along the surface and gaps between dust particles, and form a continuous dust suppressant film covering the surface of the dust source after the moisture evaporates.

2. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In S1, when pre-treating the Chinese herbal medicine residue, the residue is first spread out and obvious foreign matter is removed. Then, it is rinsed with clean water to remove attached mud and sand. Subsequently, it is dried at 50℃-80℃ until the moisture content is 8%-15%. The dried residue is then crushed and sieved through a 40-80 mesh screen. The material that passes through the screen is returned to the crushing step for reprocessing, while the material that passes through the screen is used as the Chinese herbal medicine residue powder raw material and enters S2.

3. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In S2, the alkaline solution is a sodium hydroxide solution, a potassium hydroxide solution, or a mixture of the two, with a mass concentration of 2%-10%. The raw material of Chinese herbal medicine residue powder is mixed with the alkaline solution at a mass-volume ratio of 1:8-1:25, and stirred and extracted at 50℃-90℃ for 1-5 hours to cause the fiber structure of the residue to swell with alkali and release hemicellulose. After extraction, the insoluble residue is separated by filtration or centrifugation, and the filtrate or centrifugal supernatant is collected as the alkaline extract containing the hemicellulose of the medicinal source.

4. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In step S3, when adjusting the pH of the alkaline extract containing drug-derived hemicellulose, acid is used to adjust the alkaline extract to neutral or weakly acidic. Then, ethanol is added to the adjusted extract to precipitate the drug-derived hemicellulose from the liquid phase system. The precipitate is then filtered and collected, and washed sequentially with ethanol aqueous solution and deionized water until the washing solution is close to neutral. Finally, it is dried at 40℃-70℃ to obtain drug-derived hemicellulose.

5. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In step S4, the drug-derived hemicellulose is added to an ethanol-water system or an isopropanol-water system and stirred to disperse. An alkalizing agent is added for alkalization and activation, which activates the hydroxyl groups on the drug-derived hemicellulose molecular chain. Subsequently, chloroacetic acid or sodium chloroacetate is added as a carboxymethylating agent, and the reaction is carried out at 45℃-75℃ for 1-4 hours to allow the carboxymethyl groups to be attached to the drug-derived hemicellulose molecular chain. After the reaction is completed, the system is adjusted to neutral, and the modified drug-derived hemicellulose is obtained by washing, filtering and drying.

6. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In S4, by controlling the feeding ratio of drug-derived hemicellulose, alkalizing agent, and carboxymethylating agent, the obtained modified drug-derived hemicellulose is made into a uniform dispersion in water. When the modified drug-derived hemicellulose dispersion shows obvious sedimentation after standing, the amount of carboxymethylating agent is increased or the carboxymethylation reaction time is extended. When the viscosity of the modified drug-derived hemicellulose dispersion is too high and affects the spray flowability, the amount of carboxymethylating agent is reduced or the carboxymethylation reaction time is shortened, so that the obtained modified drug-derived hemicellulose can simultaneously meet the requirements of aqueous phase dispersion and spray film formation.

7. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In S5, the bio-based composite dust suppressant mother liquor, by weight, includes: 1-8 parts modified drug-derived hemicellulose, 0.2-3 parts natural polysaccharide, 0.05-1 parts plant-derived wetting factor, and 88-98 parts water; wherein, the natural polysaccharide is one or more of xanthan gum, guar gum, sodium alginate, chitosan, or starch derivatives, and the plant-derived wetting factor is one or more of tea saponin, saponin extracts, alkyl glycosides, or plant-derived surfactant components.

8. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In S5, the phased compounding and mixing process includes the following steps: First, the modified drug-derived hemicellulose is added to a portion of water and stirred to swell, forming a modified hemicellulose dispersion; then, the natural polysaccharide is pre-swollen and added to the modified hemicellulose dispersion for homogenization and mixing, so that the natural polysaccharide and the modified drug-derived hemicellulose intertwine to form a binding and reinforcing system; finally, plant-derived wetting factor and the remaining water are added, and stirring is continued until there are no obvious agglomerated particles in the system. After filtration and standing to defoam, the bio-based composite dust suppressant mother liquor is obtained.

9. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In S6, when diluting the bio-based composite dust suppressant mother liquor and adjusting the spraying parameters, the dust particle size, surface moisture content, and external disturbance intensity of the target dust source are first collected. When the dust particle size is small, the surface moisture content is low, or the external disturbance intensity is high, the mass ratio of the bio-based composite dust suppressant mother liquor in the spray liquid is increased or the spraying amount per unit area is increased. When the dust particle size is large, the surface moisture content is high, or the external disturbance intensity is low, the mass ratio of the bio-based composite dust suppressant mother liquor in the spray liquid is reduced or the spraying amount per unit area is reduced, so that the spray liquid remains permeable, spreadable, and does not produce obvious dripping on the surface of the target dust source.

10. The method for preparing a bio-based composite dust suppressant based on modified hemicellulose of traditional Chinese medicine residue according to claim 1, characterized in that: In S6, the sprayed bio-based composite dust suppressant sequentially forms a wetting and penetration stage, a particle bonding stage, and a surface film formation stage. In the wetting and penetration stage, plant-derived wetting factors reduce the contact resistance between the spray liquid and the dust particle surface, allowing the spray liquid to enter the gaps between dust particles. In the particle bonding stage, modified drug-derived hemicellulose and natural polysaccharides adhere to the dust particle surface and connect adjacent dust particles. During the surface film formation stage, a continuous dust suppression film layer is formed as moisture evaporates, covering the surface of the dust source, thereby inhibiting dust particles from being re-raised under conditions of wind disturbance, vehicle crushing, or rain rinsing.

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