Konjac glucomannan-vinyl laurate graft copolymer coagulant as well as preparation method and application thereof

Abstract

The invention discloses a konjac glucomannan-vinyl laurate graft copolymer coagulant and a preparation method and application thereof.The method comprises the steps that konjac glucomannan is dissolved in distilled water, a redox initiation system is formed by potassium persulfate and sodium hydrogen sulfite, and then the konjac glucomannan-vinyl laurate graft copolymer coagulant is obtained; the preparation method comprises the following steps: adding an initiator into a konjac glucomannan solution in batches under the protection of nitrogen, dropwise adding a vinyl laurate monomer into a mixed solution of konjac glucomannan and the initiator, and carrying out a grafting reaction to obtain the konjac glucomannan grafted co-polyvinyl laurate coagulant. The synthesis method is simple and convenient, a synergistic effect is formed through the konjac glucomannan and the vinyl laurate monomer, the flocculation efficiency is enhanced, COD, turbidity and chromaticity in water are effectively removed, the removal rate of the COD in the water reaches 80.1% under better conditions, the removal rate of the turbidity reaches 95.6%, and the removal rate of the chromaticity reaches 92.4%.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, and particularly relates to a konjac glucomannan-vinyl laurate graft copolymer coagulant, its preparation method and application. Background Technology

[0002] Dyeing and printing wastewater contains high concentrations of dyes, heavy metals, and high salt content, while traditional coagulants face technical bottlenecks such as low removal efficiency and serious secondary pollution. Aluminum salt coagulants achieve a decolorization rate of less than 50% for water-soluble dyes, and although polyacrylamide can improve flocculation, it leaves toxic monomers that are difficult to degrade. Natural polymeric flocculants, on the other hand, suffer from slow settling and poor salt resistance. Therefore, researching a novel composite coagulant is imperative for the dyeing and printing industry. Summary of the Invention

[0003] To address the problems existing in the prior art, the purpose of this application is to provide a konjac glucomannan-vinyl laurate graft copolymer coagulant, its preparation method, and its application.

[0004] According to a first aspect of the embodiments of this application, a method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant is provided, comprising the following steps: (1) Add konjac glucomannan to distilled water and stir until completely dissolved to obtain konjac glucomannan solution; (2) Potassium persulfate and sodium bisulfite are mixed as initiators and dissolved in distilled water to obtain an initiator solution; (3) The konjac glucomannan solution was deoxygenated by passing nitrogen gas through it, and the temperature was raised. Under nitrogen protection, the initiator solution was added dropwise and stirred at a constant temperature to obtain a mixed solution of konjac glucomannan. (4) Under nitrogen protection, vinyl lauryl ester is added dropwise to the konjac glucomannan mixed solution and stirred; (5) Stop nitrogen protection, cool, concentrate, add anhydrous ethanol to the concentrate, wash the obtained solid product by vacuum filtration, dry and grind to obtain konjac glucomannan-vinyl laurate graft copolymer coagulant.

[0005] Further, in step (1), konjac glucomannan is added to distilled water at 60-80°C at a rate of 0.5-1.0 g / min, and stirred continuously for 30-60 minutes within this temperature range.

[0006] Further, in step (2), the concentration of potassium persulfate is 3~8 mmol / L, and the initiator is prepared by mixing potassium persulfate and sodium bisulfite in a molar ratio of 2:1~4:1.

[0007] Furthermore, in step (3), the amount of initiator added is 0.2% to 0.6% of the mass of vinyl lauryl ester, and the reaction temperature is 55 to 60°C.

[0008] Further, in step (4), the mass ratio of konjac glucomannan to vinyl laurate is 1:1 to 1:4, the vinyl laurate is added at a rate of 1-2 mL / min, and the mixture is stirred at 55-60℃ for 4-6 hours.

[0009] Further, step (5) specifically involves: stopping nitrogen protection, cooling to room temperature, concentrating and removing some water using a rotary evaporator, precipitating the concentrate in anhydrous ethanol, filtering, washing several times with ethanol and acetone, drying the product in a vacuum drying oven at 60~80℃ for 24 hours, and grinding to obtain powdered konjac glucomannan-vinyl laurate graft copolymer coagulant.

[0010] According to a second aspect of the embodiments of this application, a konjac glucomannan-vinyl laurate graft copolymer coagulant prepared according to the method described in the first aspect is provided.

[0011] According to a third aspect of the embodiments of this application, an application is provided of the konjac glucomannan-vinyl laurate graft copolymer coagulant as described in the second aspect in the treatment of dyeing and printing wastewater.

[0012] The technical solutions provided by the embodiments of this application may include the following beneficial effects: (1) Konjac glucomannan (KGM), as a natural polysaccharide matrix for coagulants, endows the material with unique environmental advantages and functional properties. As a renewable biopolymer, it has excellent biocompatibility and biodegradability, avoiding the environmental residue problems that may be caused by traditional synthetic flocculants. KGM itself has good water solubility and thickening properties, which enables the modified coagulant to disperse quickly and form a stable flocculation network during water treatment, significantly improving treatment efficiency.

[0013] (2) Vinyl lauryl ester (VLA), as a bio-based hydrophobic monomer, has environmentally friendly properties. Its long-chain alkyl structure, introduced through graft copolymerization, gives the originally hydrophilic KGM excellent hydrophobic properties. This hydrophobic modification enables the coagulant to effectively capture pollutants in water through hydrophobic interactions, making it particularly suitable for treating recalcitrant systems such as dyeing and printing wastewater. Compared with petroleum-based monomers, VLA not only reduces the product's dependence on fossil resources, but its biodegradability also further enhances the overall environmental compatibility of the coagulant.

[0014] (3) Graft copolymerization introduces VLA into the KGM molecular chain. Utilizing the long and flexible lauryl chain of VLA, hydrophobic microregions with stronger hydrophobic association ability and dynamic tunability are constructed on the KGM molecular chain, achieving a unique advantage of synergistic effect. This chemical modification method retains the hydrophilicity of the KGM main chain while precisely introducing hydrophobic functional groups, forming a special structure with "amphiphilicity". The KGM main chain is a rigid framework, while the long VLA chain is a flexible side chain, enabling it to form a more stable and efficient flocculation network in water. In the wastewater treatment process, the hydrophilic part ensures good material dispersion, while the hydrophobic chain segments form a three-dimensional network through intermolecular association, significantly improving flocculation efficiency.

[0015] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] Figure 1 The graph shows the removal rates of color, turbidity, and COD in wastewater under different pH conditions according to this invention.

[0018] Figure 2 The graph shows the removal rates of color, turbidity, and COD in wastewater under different reaction time conditions according to the present invention.

[0019] Figure 3 This is a comparison chart showing the removal rates of color, turbidity, and COD in wastewater between the example and the comparative examples.

[0020] Figure 4 SEM image of graft copolymerization of konjac glucomannan and vinyl laurate. Detailed Implementation

[0021] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0022] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0023] A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant may include the following steps: (1) Slowly add konjac glucomannan (KGM) to distilled water at 60-80℃ and stir continuously for 30-60 minutes within this temperature range until completely dissolved to obtain KGM solution; Among natural polysaccharide compounds, konjac glucomannan has become an important base material for the development of green functional materials due to its natural renewability, biocompatibility, and designable molecular structure. The hydrophobic long-chain alkyl groups of konjac glucomannan can strongly adsorb hydrophobic dye molecules, forming dense flocs to achieve simultaneous removal of pollutants. This material combines rapid sedimentation within seconds with complete biodegradability, and poses no ecotoxicity risk, providing a highly efficient and green solution for the treatment of dyeing and printing wastewater.

[0024] For example, the KGM addition rate can be controlled at 0.5-1.0 g / min to prevent KGM from clumping when it comes into contact with water. KGM has poor solubility in cold water and is prone to swelling and clumping. Preheating the distilled water to a specified temperature range can allow the KGM molecular chains to fully expand and significantly improve the dissolution efficiency.

[0025] (2) Mix potassium persulfate and sodium bisulfite in a molar ratio of 2:1 to 4:1 and dissolve them in distilled water as an initiator. The concentration of potassium persulfate is 3 to 8 mmol / L. Specifically, the initiator employs a combination of potassium persulfate and sodium bisulfite, leveraging the strong oxidizing properties of potassium persulfate and the reducing properties of sodium bisulfite to form a highly efficient redox system. This system rapidly generates active free radicals at relatively low temperatures, significantly improving initiation efficiency while avoiding the damage to the konjac glucomannan molecular chains caused by high temperatures. The sulfate free radicals generated by the decomposition of potassium persulfate synergistically work with the reducing environment provided by sodium bisulfite to create ideal initiation conditions for the graft copolymerization reaction, allowing the reaction to proceed efficiently within a mild temperature range.

[0026] If the ratio of potassium persulfate to sodium bisulfite deviates from the range of 2:1 to 4:1, it will affect the free radical generation rate, and thus the grafting efficiency. Preferably, the molar ratio of potassium persulfate to sodium bisulfite is 3:1. This ratio ensures efficient generation of sulfate free radicals in the redox system while maintaining the acid-base balance of the reaction system.

[0027] (3) Purge the KGM solution with nitrogen for 30 minutes to remove oxygen, raise the temperature to 55°C, and add the initiator solution dropwise under nitrogen protection. Stir at constant temperature for 30 minutes. The mass of the initiator is 0.2% to 0.6% of the predetermined mass of vinyl laurate.

[0028] (4) Slowly add vinyl laurate (VLA) to the reaction system. The mass ratio of konjac glucomannan to vinyl laurate is 1:1 to 1:4. Control the reaction temperature at 55 to 60°C and stir continuously for 4 to 6 hours while maintaining a nitrogen atmosphere.

[0029] Specifically, vinyl laurate is a functional monomer with a unique structure, containing both reactive vinyl double bonds and long-chain alkyl ester groups. As a high-purity hydrophobic monomer, it can graft copolymerize with the backbone of konjac glucomannan via free radical polymerization to form an amphiphilic polymer. Due to the presence of hydrophobic long carbon chains in its molecule, this copolymer can form a unique aggregate structure in water through hydrophobic interactions, endowing the material with excellent surface activity and adsorption properties. It maintains stable flocculation efficiency, especially under harsh water quality conditions such as high salinity and wide pH ranges, making it particularly suitable for the efficient purification of difficult-to-treat systems such as dyeing and printing wastewater and oily wastewater.

[0030] For example, VLA can be added to the reaction system at a dropping rate of 1-2 mL / min, which is beneficial for sufficient contact between the monomer and the initiator and avoids homopolymerization caused by excessively high local concentrations.

[0031] (5) After the reaction is complete, stop the nitrogen protection, cool to room temperature, and concentrate to remove some water using a rotary evaporator. Pour the concentrate into anhydrous ethanol to precipitate, filter, and wash three times with ethanol and acetone in sequence. Place the product in a vacuum drying oven at 60~80℃ and dry for 24 hours. After grinding, obtain powdered KGM-g-VLA coagulant.

[0032] The above method initiates graft copolymerization through a potassium persulfate-sodium bisulfite redox system. The synthesized konjac glucomannan-vinyl laurate copolymer combines the environmental friendliness of natural materials with the high efficiency of synthetic materials. The "hydrophobic core-hydrophilic shell" floc structure formed by it has high density and fast settling speed, providing an innovative solution for the treatment of difficult industrial wastewater such as dyeing and printing and oil-containing wastewater.

[0033] Based on this, this application also provides a konjac glucomannan-vinyl laurate graft copolymer coagulant prepared by the above method, and the application of the coagulant in the treatment of dyeing and printing wastewater.

[0034] The following description, in conjunction with specific examples, provides further details.

[0035] Example 1 A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant includes the following steps: (1) Slowly add konjac glucomannan (KGM) to distilled water and stir continuously at 70°C for 60 minutes until completely dissolved to obtain KGM solution; (2) Mix potassium persulfate and sodium bisulfite in a molar ratio of 3:1, stir and dissolve in distilled water as an initiator, and the concentration of potassium persulfate is 3 mmol / L; (3) Purge the KGM solution with nitrogen for 30 minutes to remove oxygen, and then heat it to 55°C. Under nitrogen protection, add the initiator solution dropwise, and stir at a constant temperature for 30 minutes. The total amount of initiator is 0.2% of the mass of the vinyl laurate monomer. (4) Slowly add vinyl laurate (VLA) dropwise to the reaction system, with a mass ratio of konjac glucomannan to vinyl laurate of 1:1. Control the reaction temperature at 58°C, stir continuously for 5 hours, and maintain a nitrogen atmosphere; (5) After the reaction is complete, stop the nitrogen protection, cool to room temperature, and concentrate to remove some water using a rotary evaporator. Pour the concentrate into anhydrous ethanol to precipitate, filter, and wash three times with ethanol and acetone in sequence. Place the product in a vacuum drying oven at 65°C and dry for 24 hours. After grinding, obtain powdered KGM-g-VLA coagulant.

[0036] Example 2 A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant includes the following steps: (1) Slowly add konjac glucomannan (KGM) to distilled water and stir continuously at 70°C for 60 minutes until completely dissolved to obtain KGM solution; (2) Mix potassium persulfate and sodium bisulfite in a molar ratio of 3:1, stir and dissolve in distilled water as an initiator, and the concentration of potassium persulfate is 5 mmol / L; (3) Purge the KGM solution with nitrogen for 30 minutes to remove oxygen, and then heat it to 55°C. Under nitrogen protection, add the initiator solution dropwise, and stir at a constant temperature for 30 minutes. The total amount of initiator is 0.2% of the mass of the vinyl laurate monomer. (4) Slowly add vinyl laurate (VLA) to the reaction system, with a mass ratio of konjac glucomannan to vinyl laurate of 1:1. Control the reaction temperature at 58°C, stir continuously for 5 hours, and maintain a nitrogen atmosphere. (5) After the reaction is complete, stop the nitrogen protection, cool to room temperature, and concentrate to remove some water using a rotary evaporator. Pour the concentrate into anhydrous ethanol to precipitate, filter, and wash three times with ethanol and acetone in sequence. Place the product in a vacuum drying oven at 65°C and dry for 24 hours. After grinding, obtain powdered KGM-g-VLA coagulant.

[0037] Example 3 A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant includes the following steps: (1) Slowly add konjac glucomannan (KGM) to distilled water and stir continuously at 70°C for 60 minutes until completely dissolved to obtain KGM solution.

[0038] (2) Potassium persulfate and sodium bisulfite were mixed in a molar ratio of 3:1 and dissolved in distilled water as an initiator. The concentration of potassium persulfate was 8 mmol / L. (3) Purge the KGM solution with nitrogen for 30 minutes to remove oxygen, and then heat it to 55°C. Under nitrogen protection, add the initiator solution dropwise and stir at a constant temperature for 30 minutes. The total amount of initiator is 0.2% of the mass of the vinyl laurate monomer.

[0039] (4) Slowly add vinyl laurate (VLA) dropwise to the reaction system, with a mass ratio of konjac glucomannan to vinyl laurate of 1:1. Control the reaction temperature at 58°C, stir continuously for 5 hours, and maintain a nitrogen atmosphere.

[0040] (5) After the reaction is complete, stop the nitrogen protection, cool to room temperature, and concentrate to remove some water using a rotary evaporator. Pour the concentrate into anhydrous ethanol to precipitate, filter, and wash three times with ethanol and acetone in sequence. Place the product in a vacuum drying oven at 65℃ and dry for 24 hours. After grinding, obtain powdered KGM-g-VLA coagulant.

[0041] Example 4 A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant includes the following steps: (1) Slowly add konjac glucomannan (KGM) to distilled water and stir continuously at 70°C for 60 minutes until completely dissolved to obtain KGM solution.

[0042] (2) Potassium persulfate and sodium bisulfite were mixed in a molar ratio of 3:1 and dissolved in distilled water as an initiator. The concentration of potassium persulfate was 5 mmol / L. (3) Purge the KGM solution with nitrogen for 30 minutes to remove oxygen, and then heat it to 55°C. Under nitrogen protection, add the initiator solution dropwise and stir at a constant temperature for 30 minutes. The total amount of initiator is 0.4% of the mass of the vinyl laurate monomer.

[0043] (4) Slowly add vinyl laurate (VLA) dropwise to the reaction system, with a mass ratio of konjac glucomannan to vinyl laurate of 1:1. Control the reaction temperature at 58°C, stir continuously for 5 hours, and maintain a nitrogen atmosphere.

[0044] (5) After the reaction is complete, stop the nitrogen protection, cool to room temperature, and concentrate to remove some water using a rotary evaporator. Pour the concentrate into anhydrous ethanol to precipitate, filter, and wash three times with ethanol and acetone in sequence. Place the product in a vacuum drying oven at 65℃ and dry for 24 hours. After grinding, obtain powdered KGM-g-VLA coagulant.

[0045] Example 5 A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant includes the following steps: (1) Slowly add konjac glucomannan (KGM) to distilled water and stir continuously at 70°C for 60 minutes until completely dissolved to obtain KGM solution.

[0046] (2) Potassium persulfate and sodium bisulfite were mixed in a molar ratio of 3:1 and dissolved in distilled water as an initiator. The concentration of potassium persulfate was 5 mmol / L. (3) Purge the KGM solution with nitrogen for 30 minutes to remove oxygen, and then heat it to 55°C. Under nitrogen protection, add the initiator solution dropwise and stir at a constant temperature for 30 minutes. The total amount of initiator is 0.6% of the mass of the vinyl laurate monomer.

[0047] (4) Slowly add vinyl laurate (VLA) dropwise to the reaction system, with a mass ratio of konjac glucomannan to vinyl laurate of 1:1. Control the reaction temperature at 58°C, stir continuously for 5 hours, and maintain a nitrogen atmosphere.

[0048] (5) After the reaction is complete, stop the nitrogen protection, cool to room temperature, and concentrate to remove some water using a rotary evaporator. Pour the concentrate into anhydrous ethanol to precipitate, filter, and wash three times with ethanol and acetone in sequence. Place the product in a vacuum drying oven at 65℃ and dry for 24 hours. After grinding, obtain powdered KGM-g-VLA coagulant.

[0049] Example 6 A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant includes the following steps: (1) Slowly add konjac glucomannan (KGM) to distilled water and stir continuously at 70°C for 60 minutes until completely dissolved to obtain KGM solution.

[0050] (2) Potassium persulfate and sodium bisulfite were mixed in a molar ratio of 3:1 and dissolved in distilled water as an initiator. The concentration of potassium persulfate was 5 mmol / L. (3) Purge the KGM solution with nitrogen for 30 minutes to remove oxygen, and then heat it to 55°C. Under nitrogen protection, add the initiator solution dropwise and stir at a constant temperature for 30 minutes. The total amount of initiator is 0.4% of the mass of the vinyl laurate monomer.

[0051] (4) Slowly add vinyl laurate (VLA) dropwise to the reaction system, with a mass ratio of konjac glucomannan to vinyl laurate of 2:1. Control the reaction temperature at 58°C, stir continuously for 5 hours, and maintain a nitrogen atmosphere.

[0052] (5) After the reaction is complete, stop the nitrogen protection, cool to room temperature, and concentrate to remove some water using a rotary evaporator. Pour the concentrate into anhydrous ethanol to precipitate, filter, and wash three times with ethanol and acetone in sequence. Place the product in a vacuum drying oven at 65℃ and dry for 24 hours. After grinding, obtain powdered KGM-g-VLA coagulant.

[0053] Example 7 A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant includes the following steps: (1) Slowly add konjac glucomannan (KGM) to distilled water and stir continuously at 70°C for 60 minutes until completely dissolved to obtain KGM solution.

[0054] (2) Potassium persulfate and sodium bisulfite were mixed in a molar ratio of 3:1 and dissolved in distilled water as an initiator. The concentration of potassium persulfate was 5 mmol / L. (3) Purge the KGM solution with nitrogen for 30 minutes to remove oxygen, and then heat it to 55°C. Under nitrogen protection, add the initiator solution dropwise and stir at a constant temperature for 30 minutes. The total amount of initiator is 0.4% of the mass of the vinyl laurate monomer.

[0055] (4) Slowly add vinyl laurate (VLA) dropwise to the reaction system, with a mass ratio of konjac glucomannan to vinyl laurate of 4:1. Control the reaction temperature at 58°C, stir continuously for 5 hours, and maintain a nitrogen atmosphere.

[0056] (5) After the reaction is complete, stop the nitrogen protection, cool to room temperature, and concentrate to remove some water using a rotary evaporator. Pour the concentrate into anhydrous ethanol to precipitate, filter, and wash three times with ethanol and acetone in sequence. Place the product in a vacuum drying oven at 65℃ and dry for 24 hours. After grinding, obtain powdered KGM-g-VLA coagulant.

[0057] Comparative Example 1 Wastewater was treated using only konjac glucomannan, without graft copolymerization with vinyl laurate.

[0058] Comparative Example 2 Wastewater was treated using only vinyl laurate, without combining it with konjac glucomannan.

[0059] Application examples This implementation uses wastewater from a garment factory in Zhejiang Province. The COD content of the dyeing and printing wastewater in the production process is 785 mg / L, the color is 813, and the turbidity is 1095 NTU. The coagulant prepared in Example 1 was used to treat the wastewater under different pH conditions (pH=2, 4, 6, 8, 10, 12). 0.5 g of the coagulant prepared in Example 1 was added to 1000 ml of wastewater, and the reaction was carried out at 25 degrees Celsius for 40 minutes. The removal efficiencies of color, turbidity, and COD in the dyeing and printing wastewater are shown in Table 1. Figure 1 As shown.

[0060] Table 1. Removal efficiency of color, turbidity and COD in water under different pH conditions The coagulant prepared in Example 1 was used to treat the wastewater under different reaction times (10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, and 60 minutes). 0.5 g of the coagulant prepared in Example 1 was added to 1000 ml of wastewater at a temperature of 25 degrees Celsius and a pH of 7. The removal efficiencies of color, turbidity, and COD in the dyeing and printing wastewater are shown in Table 2. Figure 2 As shown.

[0061] Table 2. Removal efficiency of color, turbidity and COD in water at different reaction times The coagulants prepared in Examples 1-7, the konjac glucomannan described in Comparative Example 1, and the vinyl laurate described in Comparative Example were each added to 1000 ml of wastewater at a temperature of 25 degrees Celsius, a pH of 7, and a reaction time of 40 minutes. The removal efficiencies of color, turbidity, and COD in the dyeing and printing water are shown in Table 3. Figure 3 As shown.

[0062] Table 3. Removal efficiency of color, turbidity, and COD in water by examples and comparative examples Table 1 clearly shows the significant impact of pH on the performance of KGM-VLA coagulant. The optimal overall performance is achieved at pH 6, with a turbidity removal rate of 71.8%, a COD removal rate of 75.8%, and a decolorization rate of 68.4%. This peak value confirms the stability of the coagulant in a neutral to slightly acidic environment, stemming from the fully extended konjac glucomannan molecular chains, which efficiently adsorb suspended particles through hydrogen bonds. Simultaneously, the hydrophobic long chains of vinyl laurate maintain their intact conformation, effectively capturing hydrophobic dyes. Performance degradation under strong acid and strong alkaline conditions reveals the material's limitations—KGM protonates and coils at pH 2, and VLA ester groups hydrolyze at pH 12, leading to a sharp drop in decolorization rate.

[0063] As shown in Table 2, as the time increased from 10 minutes to 40 minutes, the turbidity removal rate increased from 32.1% to 65.8%, and the decolorization rate jumped from 38.3% to 69.5%. This increase stems from the temporal difference in the dual-action mechanism: in the first 20 minutes, charge neutralization dominates, with the turbidity removal rate increasing by 0.78% per minute; from 30 to 40 minutes, the critical period of deep dye capture through hydrophobic association begins, and the decolorization rate improves within 10 minutes. After 40 minutes, performance declines across the board, and the turbidity removal rate decreases at 60 minutes.

[0064] The performance gradient of the seven examples verifies the decisive role of process optimization. Example 6, with its peak performance of 95.6% turbidity removal rate and 92.4% decolorization rate, demonstrates that when the grafting rate of KGM and VLA exceeds 80% and the hydrophobic microregions are uniformly distributed, triple purification can be achieved simultaneously: the KGM framework adsorbs suspended solids, the VLA long-chain captures dyes, and the network structure encapsulates organic matter. Comparative Example 1, pure konjac glucomannan, has a decolorization rate of only 37.5% due to the lack of hydrophobic groups, while Comparative Example 2, pure vinyl laurate, has a turbidity removal rate of less than 60% due to poor dispersibility. The defects of both examples jointly confirm the necessity of chemical grafting. It is worth noting that Example 3 shows an anomaly where the decolorization rate of 70.6% is lower than the turbidity removal rate of 73.9%, suggesting that uneven grafting may lead to a loss of local hydrophobic function; while Example 2, with a decolorization rate of 75.2% exceeding the turbidity removal rate of 70.1%, reflects that its higher proportion of VLA side chains makes it more suitable for high-chroma wastewater.

[0065] Comparing Examples 1-7, Example 6 demonstrated the best performance in terms of application condition adaptability. A neutral pH environment (pH=7) and a reaction time of 40 minutes provided a suitable scenario for its optimal efficiency—under these conditions, the konjac glucomannan molecular chains fully extended, while the ester bonds of the vinyl laurate remained stable, enabling the simultaneous and efficient removal of suspended solids, dissolved organic matter, and colored substances. Its low sludge yield and dense flocs further confirm that this formulation achieves an ideal balance between pollutant removal and operating costs, providing a reliable basis for industrial application.

[0066] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

Claims

1. A method for preparing a konjac glucomannan-vinyl laurate graft copolymer coagulant, characterized in that, Includes the following steps: (1) Add konjac glucomannan to distilled water and stir until completely dissolved to obtain konjac glucomannan solution; (2) Potassium persulfate and sodium bisulfite are mixed as initiators and dissolved in distilled water to obtain an initiator solution; (3) The konjac glucomannan solution was deoxygenated by passing nitrogen gas through it, and the temperature was raised. Under nitrogen protection, the initiator solution was added dropwise and stirred at a constant temperature to obtain a mixed solution of konjac glucomannan. (4) Under nitrogen protection, vinyl lauryl ester is added dropwise to the konjac glucomannan mixed solution and stirred; (5) Stop nitrogen protection, cool, concentrate, add anhydrous ethanol to the concentrate, wash the obtained solid product by vacuum filtration, dry and grind to obtain konjac glucomannan-vinyl laurate graft copolymer coagulant.

2. The method according to claim 1, characterized in that, In step (1), konjac glucomannan is added to distilled water at 60-80°C at a rate of 0.5-1.0 g / min, and stirred continuously for 30-60 minutes within this temperature range.

3. The method according to claim 1, characterized in that, In step (2), the concentration of potassium persulfate is 3-8 mmol / L, and the initiator is prepared by mixing potassium persulfate and sodium bisulfite in a molar ratio of 2:1-4:

1.

4. The method according to claim 1, characterized in that, In step (3), the amount of initiator added is 0.2% to 0.6% of the mass of vinyl laurate, and the reaction temperature is 55 to 60°C.

5. The method according to claim 1, characterized in that, In step (4), the mass ratio of konjac glucomannan to vinyl laurate is 1:1 to 1:4, the vinyl laurate is added at a rate of 1-2 mL / min, and the mixture is stirred at 55-60℃ for 4-6 hours.

6. The method according to claim 1, characterized in that, Step (5) is as follows: stop nitrogen protection, cool to room temperature, concentrate and remove some water using a rotary evaporator, pour the concentrate into anhydrous ethanol to precipitate, filter and wash several times with ethanol and acetone in sequence, place the product in a vacuum drying oven at 60~80℃ and dry for 24 hours, and grind to obtain powdered konjac glucomannan-vinyl laurate graft copolymer coagulant.

7. The konjac glucomannan-vinyl laurate graft copolymer coagulant prepared by the method according to any one of claims 1 to 6.

8. The application of the konjac glucomannan-vinyl laurate graft copolymer coagulant according to claim 7 in the treatment of dyeing and printing wastewater.

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