108 results about "Carboxymethyl-chitosan" patented technology

This invention discloses a composite hydrogel based on a polysaccharide-based hybrid dual network, its preparation method, and its applications, belonging to the field of marine polysaccharide technology. Based on the important role of amorphous calcium phosphate, a precursor in biomineral formation, in mineralization, this invention prepares a multifunctional composite hydrogel with wet bonding, antibacterial, and remineralization functions. This composite hydrogel can achieve rapid and convenient repair of enamel demineralization. This invention prepares oxidized sodium alginate via an alcohol-aqueous phase using the sodium periodate method. Sodium alginate reacts with carboxymethyl chitosan and dopamine through a Schiff base reaction to form dynamic imine bonds, thus preparing an in-situ self-crosslinking hydrogel. Simultaneously, amorphous calcium phosphate is introduced for secondary crosslinking, preparing a dense dual-network composite hydrogel. The composite hydrogel prepared by this invention has an interconnected three-dimensional porous structure, stable mechanical properties, and uniformly dispersed amorphous calcium phosphate in the form of nanospheres. The composite hydrogel prepared by this invention provides an integrated strategy with clinical translational potential for orthodontic enamel demineralization, with broad market prospects.

The application relates to the technical field of medical dressing preparation, and discloses a hemostatic, healing-promoting and antibacterial foam dressing and a preparation method thereof. The method uses sodium alginate and carboxymethyl chitosan as a composite polysaccharide matrix, mixes the two, adds a calcium chloride solution to crosslink a porous gel support, and then carries out freeze-drying to obtain a porous framework; gelatin and polyvinyl alcohol can be further added to enhance the mechanical strength, zeolite particles loaded with silver ions are added to achieve antibacterial performance, epidermal growth factor release microspheres are added to promote healing, and the dressing can be further subjected to heparinization, plasma surface modification, thrombin addition, salt precipitation pore formation and sterilization treatment. The dressing prepared by the method has the functions of synergistic hemostasis, antibiosis and healing promotion, has good biocompatibility and suitable mechanical strength, and has a simple preparation process, and can be used for various wound care.

The application provides an in-situ liquid gel-forming water-retaining agent and a preparation method and application thereof. The water-retaining agent is composed of A component and B component which are applied in steps. The A component contains an aqueous solution of a natural modified polymer, and the natural modified polymer is selected from one or two of carboxymethyl chitosan, carboxymethyl cellulose or a sodium salt thereof. The B component contains an aqueous solution of a cationic crosslinking agent, and the cationic crosslinking agent is selected from one or more cations of copper nitrate, iron nitrate, zinc nitrate, manganese nitrate, chitosan quaternary ammonium salt, calcium nitrate and magnesium nitrate. The water-retaining agent can realize the integrated functions of slow release of trace elements, water retention, soil improvement and precise nutrition supply. Furthermore, the water-retaining agent is applied to crop growth in combination with the "step-by-step drip irrigation and in-situ gel formation" technology, so that the agronomic characters of crops can be significantly improved.

This invention discloses a wheat-specific fertilizer suitable for rice-wheat rotation and its preparation method, comprising the following steps: mixing equal volumes of carboxymethyl chitosan solution, composite biochar dispersion, and agar solution, then adding sodium tripolyphosphate solution dropwise, stirring, allowing to stand, dialyzing, and freeze-drying to obtain hydrogel particles; swelling the hydrogel particles in a mixed aqueous solution of urea and superphosphate, filtering, and vacuum drying to obtain the wheat-specific fertilizer suitable for rice-wheat rotation; this invention uses a coating material to coat composite biochar powder, nitrogen fertilizer, and phosphate fertilizer, and improves the utilization rate of nitrogen and phosphate fertilizer through the slow-release effect of the coating material; by adsorbing fixed trace metal elements through the coating material, the slightly acidic state of the phosphate fertilizer during dissolution is used to convert the adsorbed fixed trace metal elements into a free state, and then titanium aluminum carbide promotes the movement of the free trace metal elements, thereby promoting the absorption and utilization of trace metal elements by wheat roots and improving wheat yield and quality.

This invention belongs to the field of biomedical materials technology, specifically disclosing a composite material for promoting the repair of soft tissue defects in the maxillofacial region and its preparation method. The composite material comprises the following raw materials: oxidized hyaluronic acid, carboxymethyl chitosan, dopamine-functionalized hydroxyapatite nanoparticles, strontium salt, copper salt, glycerol, and deionized water. The preparation method includes: firstly, strontium salt and copper salt are hierarchically loaded onto the surface of dopamine-functionalized hydroxyapatite nanoparticles via a dual mechanism of "lattice substitution-surface coordination," and then, together with oxidized hyaluronic acid and carboxymethyl chitosan, construct a "dynamic covalent-hydrogen bond-coordination bond" triple synergistic network through Schiff base reaction, hydrogen bonding, and coordination bonds. This invention solves the technical problems of poor wet surface adhesion, low mechanical strength, single function, and easy burst release of ions in existing repair materials, exhibiting excellent effects such as sequential antibacterial and repair-promoting properties, high adhesion strength, and long-lasting sustained release.

This invention relates to a biodegradable barrier antibacterial moisture-absorbing film, which consists of two layers: a quaternary ammonium salt chitosan / hydroxyethyl cellulose composite layer and a methacrylated gelatin / methacrylated carboxymethyl chitosan composite layer. The two layers are bonded together by casting, biaxial stretching, and hot pressing, and a reaction is achieved between them to achieve a tight bond. The composite film has good tensile strength, ductility, and tear resistance. Under dry conditions, the film has good oxygen and carbon dioxide barrier properties, and also has good moisture absorption. This film can be used in packaging applications requiring barrier, moisture absorption, and antibacterial properties.

The application belongs to the technical field of biotechnology, and particularly relates to application of albumin polypeptide gel beads in a product for treating or preventing sarcopenia. Egg white protein is used as raw material to extract protein, and albumin dipeptide-based peptidase-IV inhibitory peptide is prepared through a biological enzymolysis method. Bioinformatics analysis is used to screen out the inhibitory peptide TPYMFP, and the IC50 value of the inhibitory peptide TPYMFP for dipeptide-based peptidase-IV reaches 3.12 ± 0.49 mmol / L. Further, the optimal preparation conditions of sodium alginate SA and carboxymethyl chitosan CMCS-based gel beads CMCS / SA / TPYMFP are explored. When the SA concentration is 1.5% (w / v), the CMCS concentration is 0.5% (w / v), and the CaCl2 concentration is 1% (w / v), the polypeptide encapsulation rate is increased to 98.26% ± 0.25%. It is verified that the albumin polypeptide gel beads have good pH response characteristics, and efficient protection and intestinal target delivery of the sarcopenia inhibitory peptide are realized. The albumin polypeptide gel beads are applied to preparation of a product for treating or preventing sarcopenia, or in preparation of a related product for increasing muscle mass and strength.

The application discloses a degradable organic-inorganic composite film and a preparation method and application thereof, and belongs to the technical field of composite materials. The method comprises the following steps: (1) preparing a calcium phosphate nanocluster precursor by using an organic amine stabilizer, a calcium source, a phosphorus source and an organic solvent, and further separating the calcium phosphate nanocluster; (2) mixing the calcium phosphate nanocluster and a natural polymer material to prepare a uniformly dispersed emulsion, wherein the natural polymer material comprises carboxymethyl chitosan and an alginate, and film is prepared by using the emulsion; in the film preparation process, an evaporation-induced self-assembly process occurs, the calcium phosphate nanocluster is phase changed into crystalline rod-shaped hydroxyapatite nanocrystals, and the natural polymer material is combined, so that the degradable organic-inorganic composite film is obtained. The mechanical property of the organic-inorganic composite film is adjustable, the organic-inorganic composite film can be directly degraded in soil, and has a wide application prospect in the fields of packaging, agriculture, medical treatment and the like.

This invention belongs to the field of biomedical materials technology, specifically relating to an oxidized hyaluronic acid / carboxymethyl chitosan hemostatic sponge and its preparation method. The preparation method includes: oxidizing hyaluronic acid with sodium periodate to obtain oxidized hyaluronic acid; preparing aqueous solutions of oxidized hyaluronic acid and carboxymethyl chitosan; mixing the two solutions and forming a hydrogel through a Schiff base reaction between aldehyde and amino groups; cryogelatinizing the hydrogel at low temperature and then freeze-drying it under vacuum to obtain an expandable hemostatic sponge with a three-dimensional interconnected porous structure. Upon contact with blood, the sponge of this invention rapidly absorbs water and expands, increasing in volume by more than three times, forming a tight physical seal. Simultaneously, it adsorbs and activates platelets to accelerate coagulation, achieving highly efficient hemostasis. This sponge exhibits excellent biocompatibility, is completely degradable in vivo, and the preparation process is mild and requires no toxic cross-linking agents. It can be used for rapid hemostasis of deep, irregular, and non-compressible bleeding wounds.

This invention discloses a GABA-loaded hydrogel microneedle, its preparation method, and its application, belonging to the field of biomedical materials technology. This drug-loading system uses polypyrrole-grafted gelatin (PPy) as the loading medium. ‑ Using gelatin (GelMA), carboxymethyl chitosan, and methacrylate gelatin (GelMA) as a matrix, a three-dimensional network hydrogel (PPG@Gel) is formed through cross-linking with aldehyde-modified polyethylene glycol (PEG-CHO) and loaded with γ-aminobutyric acid (GABA). The preparation process includes GelMA modification, PPy-GelMA graft polymerization, PEG-CHO cross-linking agent synthesis, and mixing of each component with GABA to form a precursor hydrogel (PPG@Gel), which can ultimately be prepared as a microneedle patch (PPG@MN). This invention utilizes the excellent biocompatibility and permeability of hydrogels to achieve precise local delivery of GABA to lesions in inflammatory skin diseases. GABA can target and inhibit abnormal inflammatory responses, regulate epidermal cell function, and repair the skin barrier, while avoiding the adverse reactions and cost drawbacks of existing treatments. The hydrogel raw materials are readily available and highly safe, allowing for continuous drug delivery to improve patient compliance. It is suitable for the treatment of various inflammatory skin diseases such as psoriasis and eczema, and has significant clinical application value.

The present invention describes novel drug-carrying nanoparticles called bionanocarriers capable of modulating the cellular redox system and targeting the cancerous tumor.Specifically, the invention relates to a nanomedicine strategy for combating cancerous tumor cells, a strategy that aims to target the tumor, and consists of providing quercetin-linked magnetite nanoparticles (Q): (MNPs Q), and 3,5-dimaleylbenzoic acid-linked magnetite nanoparticles (A3'5DMB): (MNPs A3'5DMB)M; both types of nanoparticles were subsequently encapsulated with chitosan (Qs) and O-carboxymethyl chitosan (O-CMQs), functionalized with 11-mercaptoundecanoic acid (MUDA), and finally the anti-ABCC3 antibody was attached to the polymer phase, which was used as a selective driver of the delivery process of the encapsulated nanoparticles, thus carrying out the construction of the bionanocarriers: BNC-1: MNPs-Q-Ab; BNC-2: MNPs-a3'5DMB-Ab.Its manufacturing method and the tests of its biological functionality, its stability, the degradation of the encapsulation for the tumor microenvironment, the controlled release profile of the drugs Q and A3'5DMB, selective cell uptake, intracellular localization, cytotoxic effect on steroids of hepatocellular carcinoma cells with altered redox balance and induction of apoptosis, as well as its safety on normal cells, are described.

The application provides a kind of injectable responsive hydrogel loaded with chitosan oligosaccharide-gallic acid octyl ester and its preparation method and application, and the preparation method comprises: chitosan oligosaccharide-gallic acid octyl ester conjugate is added into carboxymethyl chitosan solution to obtain a mixed solution;The mixed solution and the oxidized tannic acid solution are mixed to form an injectable responsive hydrogel.The three-dimensional hydrogel network formed by carboxymethyl chitosan and oxidized tannic acid is constructed, chitosan oligosaccharide-gallic acid octyl ester is stably loaded in the gel system, can form a physical barrier in the local wound and provide sustained support, thereby significantly improving the retention capacity of antibacterial components in the wound site, prolonging its effective action time, reducing the need for repeated administration.Effectively solve the problem that antibacterial functional materials are difficult to stay in humid infected wounds for a long time and are easy to lose with exudate, can be applied and prepared into antibacterial drugs.

The application discloses a kind of PH dual-response type concrete multifunctional admixture and preparation method thereof.The concrete multifunctional admixture preparation method is as follows: first, carboxymethyl chitosan, chitosan, nano silicon dioxide, cellulose acetate, N,N'-methylene bisacrylamide, ammonium persulfate / tetramethyl ethylenediamine mixture, nano hydrated calcium silicate are added to acetic acid solution, and hybrid particles are obtained after ultrasonic continuous dispersion;Second, polycarboxylate superplasticizer, acrylamide, sodium alginate and nano halloysite particles are uniformly stirred by magnetic force to form a mixed dispersion solution;Finally, hybrid particles are added to the mixed dispersion solution to obtain a concrete multifunctional admixture.The concrete admixture can not only remain stable under polycarboxylate superplasticizer solution storage conditions, but also can not increase the viscosity of concrete after being added to concrete, so that it can maintain good mixing performance, achieve good water retention and early strength effect.

This invention discloses a method for preparing a highly antioxidant, color-changing, intelligent active food preservation film containing bilberry anthocyanins, belonging to the field of food preservation technology. An ACNs-CHC / CMC-WPI nanocomposite is constructed through the encapsulation of chitosan hydrochloride (CHC), carboxymethyl chitosan (CMC), and whey protein isolate (WPI). Using corn starch, chitosan, and 30 wt% glycerol as a base material, the anthocyanin-loaded nanocomposite is introduced as a functional component and formed on the surface of an acrylic sheet via solution casting. This food preservation film exhibits excellent mechanical properties and effectively inhibits spoilage and the proliferation of pathogenic bacteria in high-protein aquatic foods (such as white shrimp), reduces the formation rate of biogenic amines, and significantly slows down the deterioration process of food quality. Furthermore, the surface color of the film changes with the pH value of the target meat, providing a visual monitoring method for food freshness and can also be used for rapid detection of food freshness.

The application provides an injectable hydrogel for endometrial repair and / or prevention of adhesion of uterine cavity and a preparation method and application thereof, and belongs to the technical field of biomedical materials. The injectable hydrogel is composed of a base gel and a decellularized matrix distributed in the base gel; the base gel is composed of a cross-linked carboxymethyl chitosan gel and a carbomer gel; the base gel has an interpenetrating or semi-interpenetrating double network structure; and the cross-linked carboxymethyl chitosan gel is a chemical cross-linked carboxymethyl chitosan gel. In the application, the injectable hydrogel forms a base gel with an interpenetrating or semi-interpenetrating double network structure by using a cross-linked carboxymethyl chitosan gel and a carbomer gel, and is compounded with a decellularized matrix, so that the injectable hydrogel has high elasticity and high adhesion, can effectively prevent adhesion and repair damaged tissues, has a long action time, and has good biocompatibility.

The application relates to a preparation method of a carboxymethyl chitosan-phytic acid-glycerol composite battery diaphragm and belongs to the field of organic composite battery diaphragms. The application solves the problem that the existing battery diaphragm is difficult to consider biological safety and electrochemical performance. In the application, carboxymethyl chitosan is fully dissolved in deionized water, 50% phytic acid solution, glycerol and auxiliary materials are added, and stirring is conducted until no flocculent insoluble substance is generated to obtain a composite liquid; the composite liquid is centrifuged to remove bubbles, and then constant temperature drying is conducted in a drying box to obtain the carboxymethyl chitosan-phytic acid-glycerol composite battery diaphragm. The carboxymethyl chitosan-phytic acid-glycerol composite battery diaphragm prepared in the application has the characteristics of being edible, high conductivity, compactness, porosity, low swelling rate and excellent tensile strength and the like. The application is mainly applied in the field of swallowable batteries.

This invention discloses a multimode liquid chromatography packing material for aminated silica gel modified with an interpenetrating network hydrogel, its preparation method, and its applications, relating to the field of high-performance liquid chromatography (HPLC) separation and analysis technology. The packing material is obtained by modifying the surface of aminated silica gel with an interpenetrating network hydrogel formed from carboxymethyl chitosan and poly(N-isopropylacrylamide) using chemical polymerization. The packing material provided by this invention can be used for the separation and analysis of compounds of different polarities. The interpenetrating network structure formed by the two monomers gives the hydrogel-modified layer higher mechanical strength, and the different interaction sites enable multimode (hydrophilic chromatography mode, hydrophobic chromatography mode, and ion chromatography mode) separation and analysis of compounds with different polarities. The preparation method provided by this invention is simple, and the prepared packing material has significant application potential in the field of chromatographic separation and analysis.

The application discloses a multifunctional gradient structure artificial skin and a preparation method and application thereof, and belongs to the technical field of biomaterials and biomedical engineering. The upper layer of the application is a silica gel layer, which is used for simulating epidermis to keep a moist environment of a wound and simultaneously plays a barrier role; the intermediate layer is a degradable polymer / natural bioactive protein composite layer, which is used for enhancing mechanical properties; and the lower layer is a hydrogel layer, which is formed by cross-linking hyaluronic acid and carboxymethyl chitosan to form a Schiff base bond and then cross-linking collagen through catalysis. The composition of the hydrogel layer is a component of an extracellular matrix, and the three-dimensional network structure formed is beneficial to cell growth, can simulate a dermis layer to play a function of promoting tissue regeneration and remodeling, and finally the artificial skin with good mechanical strength, capable of preventing wound infection and promoting wound healing is obtained.

The application discloses a kind of nanofiber / wheat gluten protein foam composite medical dressings and preparation method thereof, and preparation method includes the following steps: wheat gluten protein powder, plasticizer and alkali are dispersed in water, polyvinyl alcohol is added after heating and shearing stirring, and the wheat gluten protein foam is obtained after freeze-drying;Sodium alginate, polyvinyl alcohol and carboxymethyl chitosan aqueous solution are mixed to obtain electrospinning solution;Calcium chloride aqueous solution is coated on the wheat gluten protein foam, and electrospinning is carried out using electrospinning solution, to obtain nanofiber / wheat gluten protein foam composite medical dressing.The application takes wheat gluten protein foam as base layer, and takes sodium alginate / polyvinyl alcohol / carboxymethyl chitosan nanofiber membrane as surface layer (wound contact layer) to prepare a kind of composite medical dressing, which has excellent liquid absorption rate, micro-nano porous structure on the wound contact surface, and can be biodegraded, to provide a new type of composite medical dressing for the nursing of chronic wound.

The application relates to the technical field of medical textile materials, and discloses an antibacterial and breathable medical gauze sheet, which comprises a base material and an antibacterial functional layer loaded on the base material, and the functional layer is formed by chemical reaction of carboxymethyl chitosan, tannic acid, boric acid, citric acid and zinc ions. Through boric acid complexation and citric acid competitive coordination, a double interpenetrating network structure of covalent bonds and coordination bonds is formed inside and outside the gauze fibers. The structure effectively inhibits the oxidative browning of tannic acid and eliminates the difference in the skin-core distribution of the functional components. The obtained gauze sheet is not only high in whiteness and good in breathability, but also has excellent washing fastness and long-acting and broad-spectrum antibacterial performance.

This invention provides a thermosensitive peppermint essential oil microcapsule and its preparation method. First, peppermint essential oil is encapsulated in yeast cells to prepare microcapsules, improving the problems of volatility and poor stability of peppermint essential oil. Second, the microcapsules are immersed in Bacillus subtilis fermentation broth, where enzymes such as glucanase and mannoglucase in the fermentation broth enzymatically modify the microcapsules, partially converting polysaccharides on the cell wall into oligosaccharides and hydrolyzing long molecular chains into shorter ones, thus improving the dispersibility of the microcapsules in water. Finally, the enzymatically modified microcapsules are immersed in a polylysine-carboxymethyl chitosan solution for surface modification, ultimately obtaining thermosensitive peppermint essential oil microcapsules, broadening the application of peppermint essential oil in the field of food antibacterial preservation.

The present application relates to the technical field of biological medicine, in particular to a mesenchymal stem cell exosome composition for repairing wound and a preparation method thereof.The preparation raw material of the exosome composition comprises the following components in parts by weight: mesenchymal stem cell exosome 0.15-0.2 parts, modified hyaluronic acid 3-5 parts, modified dandelion extract 5-8 parts, and carboxymethyl chitosan 2-3 parts.The exosome composition prepared by the present application can effectively promote wound repair.

This invention provides a modified fucoidan composite hydrogel, its preparation method, and its application, belonging to the field of hydrogel technology. The preparation method of the composite hydrogel includes the following steps: dissolving fucoidan in an organic solvent, then adding a sulfonating agent to carry out a sulfation reaction; after the reaction, allowing it to stand, precipitate, wash, dry, and grind sequentially to obtain persulfated modified fucoidan; preparing a persulfated modified fucoidan solution, then mixing it evenly with a carboxymethyl chitosan solution, a laver polysaccharide solution, and a hyaluronic acid solution; then adding a polyethylene glycol solution, a 1,4-phenylenediboric acid solution, salmon protein active peptides, and docosahexaenoic acid; finally, adding a crosslinking agent to obtain a mixed solution, and stirring to obtain a composite polysaccharide hydrogel. This composite hydrogel has good mechanical properties and biocompatibility, and can accelerate the healing of chronic wounds in type 2 diabetes.

This invention belongs to the field of biomedical materials and relates to a method for preparing a multi-dynamically bonded hydrogel based on polysaccharides from the traditional Chinese medicine *Solanum nigrum* and its application. *Solanum nigrum* is initially extracted and precipitated with alcohol to obtain crude polysaccharides. The polysaccharides are then deproteinized using the Sevag method to obtain a crude polysaccharide solution. After dialysis and freeze-drying, crude polysaccharide is obtained. The crude product is separated and purified to obtain homogeneous polysaccharides. The homogeneous polysaccharide solution is reacted with sodium periodate solution in the dark, followed by dialysis, purification, and freeze-drying to obtain oxidized *Solanum nigrum* polysaccharide OBY. OBY is dissolved in boric acid solution to obtain solution A. Carboxymethyl chitosan is dissolved in polyvinyl alcohol solution to obtain solution B. After the solutions A and B have fully reacted, they are placed in a mold to obtain a multi-dynamically bonded hydrogel based on *Solanum nigrum* polysaccharides. This hydrogel can be applied to the preparation of drugs for chronic wound repair, providing a novel material system and application strategy for developing new wound dressings with excellent physicochemical properties, intelligent response characteristics, and active repair functions.

The application relates to a sample pretreatment method for pyrite element analysis. First, a pretreatment agent is prepared: carboxymethyl chitosan is activated on the surface through NHS / EDC, and then reacts with phosphoethanolamine to obtain the pretreatment agent; secondly, a pyrite sample is crushed into particles, and is fully ground into powder together with NaOH, NaNO3 and the pretreatment agent; then, the temperature is increased to 180-250 DEG C and then to 350-450 DEG C for heat preservation; the sintered solid is transferred into a beaker, hot nitric acid solution is added, ultrasonic is used to dissolve the solid, and after cooling, filtration is carried out into a volumetric flask, and dilute nitric acid is used for constant volume to obtain a sample to be tested. The treatment method avoids the use of a large amount of concentrated acid and perchloric acid, the reagent consumption is small, and the method is environment-friendly; the treated sample is determined by an ICP-MS instrument and the like, and the recovery rate can be ensured to be above 95%; compared with a standard value, the RSD value is not more than 5%, and the accuracy is good.

This invention discloses a biodegradable bamboo fiber mulch film, belonging to the field of agricultural environmental protection materials technology. The mulch film is composed of a bamboo fiber-PHA grafted reinforcement and a dual-network crosslinked matrix. The bamboo fiber-PHA grafted reinforcement is generated in situ through the esterification reaction of hydroxyl groups on the bamboo fiber surface with the carboxyl groups at the ends of polyhydroxy fatty acid esters. The dual-network crosslinked matrix is ​​formed by the Schiff base reaction of oxidized sodium alginate and carboxymethyl chitosan to form a dynamic covalent network, while simultaneously forming a hydrogen bond network with polyvinyl alcohol. This invention solves the technical problem of poor interfacial compatibility between natural fibers and polymer matrices through bamboo fiber surface grafting modification. The dual-network crosslinked system achieves a synergistic improvement in mechanical strength and controllable degradation. The resulting mulch film has a tensile strength ≥35MPa, an elongation at break ≥120%, and a degradation rate ≥85% after 90 days of soil burial. It also possesses water retention, light conversion, and slow-release nutrient functions, and is completely biodegradable without residue, making it suitable for planting various crops.

This invention relates to a flotation depressant and flotation method for recovering copper from magnetically separated iron tailings, specifically in the field of mineral flotation technology. The flotation depressant comprises: sulfonated modified tannin, sodium cyanurate, carboxymethyl chitosan, and carbonates. The flotation depressant provided by this invention, through the synergistic effect of its components, achieves highly efficient selective inhibition of pyrite at a pulp pH of 8-9, while having no significant inhibitory effect on chalcopyrite. It is suitable for low-grade, fine-grained, disseminated magnetically separated iron tailings, yielding copper concentrate with a Cu grade ≥19.22% and a recovery rate ≥72.50%. This invention solves problems such as foaming and stickiness, equipment scaling, and difficulty in meeting alkalinity standards in traditional high-alkali lime processes. It has advantages such as low alkali content, high efficiency, and environmental friendliness, and has broad prospects for industrial application.

The application discloses a preparation method of a carboxymethyl chitosan / lignin / curcumin / citric acid fresh-keeping composite film material, which comprises the following steps: step 1, mixing carboxymethyl chitosan with deionized water to obtain a carboxymethyl chitosan dispersion; step 2, dispersing lignin in deionized water, pouring into the carboxymethyl chitosan dispersion to form a carboxymethyl chitosan / lignin dispersion; step 3, dispersing curcumin in anhydrous ethanol, uniformly mixing with Tween 80, and adding into the carboxymethyl chitosan / lignin dispersion to form a carboxymethyl chitosan / lignin / curcumin dispersion; and step 4, dissolving citric acid in deionized water, adding into the carboxymethyl chitosan / lignin / curcumin dispersion, and adding glycerol to obtain the carboxymethyl chitosan / lignin / curcumin / citric acid fresh-keeping composite film material. The obtained fresh-keeping composite film material comprises carboxymethyl chitosan, lignin, curcumin, citric acid and glycerol, and has the characteristics of strong mechanical property, good antibacterial property, film forming property and swelling property.