A pre-filtered fiber modified material, its preparation method and application

Abstract

This invention relates to a pre-filter fiber modified material, its preparation method, and its application. The pre-filter fiber modified material includes pre-filter fibers before a water treatment membrane and a phosphorylated adhesive material loaded thereon. This invention also provides a method for preparing the pre-filter fiber modified material, comprising: dissolving the adhesive material in an organic acid solution to obtain an adhesive aqueous solution; adding a phosphoric acid solution to the adhesive aqueous solution to obtain a phosphorylated adhesive slurry; immersing the pre-filter fibers before the water treatment membrane in the phosphorylated adhesive slurry, removing them, and then immersing and curing them in a weak alkaline solution to obtain the pre-filter fiber modified material. This invention also provides an application of the pre-filter fiber modified material of this invention in aqueous solutions containing heavy metals. This invention solves the problem of incomplete removal of heavy metals from drinking water or the easy generation of secondary pollution.

Description

Technical Field

[0001] This invention relates to the field of water treatment functional materials technology, specifically to a pre-filter fiber modified material, its preparation method, and its application. Background Technology

[0002] Currently, most small-scale self-contained water treatment systems rely on membrane filtration, including nanofiltration and reverse osmosis membranes. While these methods effectively remove most heavy metal ions, the retained heavy metals are discharged with the concentrate, causing secondary pollution. Therefore, modifying the pre-treatment filter material to possess excellent heavy metal adsorption capacity, thereby preventing them from entering the membrane module, is undoubtedly the optimal choice.

[0003] PP cotton fiber, commonly known as doll cotton, hollow cotton, or filling cotton, is a man-made chemical fiber made of polypropylene fiber. Polypropylene fiber is a type of plastic with a relatively low density; it's important to note that polypropylene fiber is different from polyester fiber. Based on the manufacturing process, it mainly comes in two types: regular fiber and hollow fiber. This product has good resilience, a smooth feel, a relatively low price, and good warmth retention, and is widely used in toy filling, clothing, bedding, spray-bonded cotton, and water purification equipment. However, in most water purification processes, cotton fiber, as a pre-filtration material before water treatment membranes, can only effectively intercept insoluble impurities in the raw water, and has no ability to resist soluble pollutants such as heavy metals.

[0004] Chitosan is a derivative of chitin produced by hydrolysis under alkaline conditions and the removal of some acetyl groups. Also known as chitosan polysaccharide, aminopolysaccharide, and chitin, its chemical name is β-(1→4)-2-amino-2-deoxy-D-glucose. In nature, the annual biosynthesis of chitin is approximately 10 billion tons, making it the second largest organic resource on Earth after cellulose, a vast treasure trove for humankind. Chitosan is abundant in resources. Research indicates that chitosan is a green, environmentally friendly, and renewable biomass material with the ability to complex most heavy metal ions. Therefore, it holds promise for use as a pre-treatment filtration material for membranes. However, some studies have shown that the complexes formed between some heavy metals (such as divalent copper, divalent nickel, and divalent cadmium) and chitosan are unstable and prone to desorption under long-term immersion conditions, leading to a gradual decrease in the filtration efficiency of the pre-treatment filtration material. Summary of the Invention

[0005] One objective of this invention is to provide a pre-filter fiber modified material and its preparation method to improve the adsorption stability of the pre-filter fiber material before water treatment membranes. Another objective of this invention is to provide an application of the pre-filter fiber modified material to solve the problem of incomplete removal of heavy metals in drinking water or the easy generation of secondary pollution.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A pre-filtration fiber modification material includes pre-filtration fibers for water treatment membranes and a phosphoric acid adhesive material loaded on the pre-filtration fibers for water treatment membranes, wherein the pre-filtration fibers for water treatment membranes are modified by the phosphoric acid adhesive material.

[0008] Based on the aforementioned technical methods, by loading phosphorylated adhesive materials onto the pre-filtration fibers before water treatment membranes, the grafted phosphate groups enhance the binding force of the adhesive materials to heavy metals in water, thereby effectively improving the adsorption stability of the pre-filtration fibers (long-term immersion stability has been proven through multiple regeneration tests). Furthermore, the introduction of phosphorylated adhesive materials increases the specific surface area of ​​the pre-filtration fibers, resulting in a higher adsorption capacity. Tests have demonstrated that the modified pre-filtration fibers exhibit good adsorption performance within a pH range of 4–10, with minimal impact from common coexisting anions in water, thus improving the adaptability of the modified pre-filtration fibers. Simultaneously, the adsorption rate exceeds 80% after three or more cycles of adsorption and regeneration, exhibiting excellent regeneration performance. Therefore, using the modified pre-filtration fibers as a pre-treatment material for filters effectively shifts the treatment process upstream.

[0009] Preferably, the pre-filtration fiber before the water treatment membrane is selected from PP cotton fiber and / or activated carbon.

[0010] Preferably, the adhesive material in the phosphorylated adhesive material is selected from at least one of chitosan, carrageenan, and sodium alginate.

[0011] Preferably, the pre-filtration fiber before the water treatment membrane is selected from PP cotton fiber.

[0012] In this invention, PP cotton fiber refers to various water treatment filter media made primarily of polypropylene fiber filaments and polypropylene fiber filaments, including PP cotton fiber filter cloth and its roll filter cartridges, PP cotton fiber yarn and its wound filter cartridges, and PP cotton fiber velvet filled filter media.

[0013] Preferably, the phosphorylated adhesive material is selected from phosphorylated chitosan.

[0014] By loading phosphorylated chitosan onto PP cotton fibers, the grafted phosphate groups enhance the binding force of the adhesive material to heavy metals in water, thereby effectively improving the adsorption stability of PP cotton fibers (long-term immersion stability was demonstrated in multiple regeneration tests). Furthermore, the introduction of phosphorylated chitosan increases the specific surface area of ​​the PP cotton fibers, resulting in a higher adsorption capacity for the modified PP cotton fiber material. Experiments have shown that the modified PP cotton fiber material exhibits good adsorption performance within a pH range of 4–10, with minimal impact from commonly coexisting anions in water, thus improving its adaptability. Moreover, after three or more cycles of adsorption and regeneration, the adsorption rate exceeds 80%, demonstrating excellent regeneration performance. Therefore, using the modified PP cotton fiber material as a pretreatment material for filters effectively shifts the barrier to entry upstream.

[0015] This invention also provides a method for preparing a pre-filtered fiber modified material, comprising the following steps:

[0016] S1. Dissolve the adhesive material in an organic acid solution and stir with a mechanical stirrer until the adhesive material is completely dissolved until it becomes a translucent golden-yellow gel-like solution, thus obtaining an adhesive aqueous solution.

[0017] S2. Add the phosphoric acid solution to the adhesive aqueous solution to obtain a phosphorylated adhesive slurry;

[0018] S3. The pre-filtration fiber before the water treatment membrane is immersed in the phosphoric acid adhesive slurry, and then placed in a weak alkaline solution for immersion and curing to obtain the pre-filtration fiber modified material.

[0019] Based on the above technical means, by placing phosphoric acid in an adhesive aqueous solution, the adhesive material is phosphorylated, which effectively enhances the binding force of the adhesive material to heavy metals in the water. Then, the pre-filtration fiber before the water treatment membrane is immersed in the phosphorylated adhesive slurry to modify the pre-filtration fiber before the water treatment membrane, thereby effectively increasing the adsorption performance and environmental adaptability of the pre-filtration fiber before the water treatment membrane. At the same time, the phosphorylated adhesive material increases the specific surface area of ​​the pre-filtration fiber before the water treatment membrane, thereby effectively improving the adsorption capacity of the pre-filtration fiber before the water treatment membrane.

[0020] Preferably, in step S1, the solid-liquid ratio of the adhesive material to the organic acid solution is 1g to 10g: 100mL.

[0021] Preferably, the organic acid solution is at least one of formic acid solution, acetic acid solution and propionic acid solution.

[0022] Preferably, the volume concentration of the organic acid in the organic acid solution is 1% to 3%.

[0023] Preferably, the solid-liquid ratio of the adhesive material to the phosphoric acid solution is 1g to 10g: 0.5 to 2.5mL.

[0024] By controlling the solid-liquid ratio of the adhesive material to the phosphoric acid solution to 1g~10g:0.5~2.5mL, the problem of insufficient sites caused by an excessively high solid-liquid ratio and the problem of poor slurry viscosity and poor loading effect caused by an excessively low solid-liquid ratio are effectively avoided.

[0025] Preferably, step S2 includes: adding a phosphoric acid solution to the adhesive aqueous solution and reacting at room temperature for 0.5 to 3 hours to obtain a phosphoric acid adhesive slurry;

[0026] The concentration of phosphoric acid in the phosphoric acid solution is 75% to 85%.

[0027] Preferably, step S3 includes: diluting the phosphoric acid adhesive slurry with water by 3 to 5 times, then immersing the pre-filter fiber before the water treatment membrane in the diluted phosphoric acid chitosan slurry, ultrasonically treating it for 6 to 15 minutes at a power of 40 kHz, then allowing it to stand for 6 to 24 hours, and finally removing it and placing it in a weak alkaline solution for curing to obtain the pre-filter fiber modified material.

[0028] By employing ultrasonic treatment and rationally controlling the time and power of ultrasonic treatment, the fiber channels are effectively ensured to be rapidly and uniformly wetted by the slurry.

[0029] Preferably, in step S3, the addition ratio of the pre-filtration fiber before the water treatment membrane to the diluted phosphoric acid adhesive slurry is 2-10 cm⁻¹. 3 100mL.

[0030] Preferably, the weak alkaline solution is an ammonia solution, and the concentration of ammonia in the ammonia solution is 3% to 9%.

[0031] Preferably, the soaking and curing time is 4 to 12 hours.

[0032] By soaking in alkaline conditions, the phosphorylated adhesive slurry that wets the surface of the pre-filter fiber before the water treatment membrane is cured, which increases the adhesion of the phosphorylated adhesive slurry to the surface of the pre-filter fiber before the water treatment membrane, thereby effectively enhancing the hydraulic stability of this active layer.

[0033] Preferably, when the pre-filtration fiber before the water treatment membrane is PP cotton fiber and the adhesive material is chitosan, the preparation method of the PP cotton fiber modified material includes the following steps:

[0034] S1. Dissolve chitosan in an organic acid solution and stir with a mechanical stirrer until the chitosan is completely dissolved and a translucent golden-yellow gel-like solution is obtained.

[0035] S2. Add the phosphoric acid solution to the chitosan solution to obtain phosphorylated chitosan slurry;

[0036] S3. Immerse the PP cotton fiber in the phosphorylated chitosan slurry, remove it, and then immerse it in a weak alkaline solution to solidify it, thereby obtaining the PP cotton fiber modified material.

[0037] By placing phosphoric acid in a chitosan solution to phosphorylate the chitosan, the binding force of chitosan to heavy metals in water is effectively enhanced. Then, PP cotton fibers are soaked in the phosphorylated chitosan slurry to modify the PP cotton fibers, thereby effectively increasing the adsorption performance and environmental adaptability of the PP cotton fibers. At the same time, the phosphorylated chitosan increases the specific surface area of ​​the PP cotton fibers, thereby effectively improving the adsorption capacity of the PP cotton fibers.

[0038] Preferably, in S1, the solid-liquid ratio of chitosan to organic acid solution is 1g to 10g: 100mL.

[0039] Preferably, the solid-liquid ratio of the chitosan to the phosphoric acid solution is 1g-10g:0.5-2.5mL.

[0040] By controlling the solid-liquid ratio of chitosan to phosphoric acid solution to 1g-10g:0.5-2.5mL, the problem of insufficient sites caused by an excessively high solid-liquid ratio and the problem of poor slurry viscosity and poor loading effect caused by an excessively low solid-liquid ratio are effectively avoided.

[0041] Preferably, step S2 includes: adding a phosphoric acid solution to the chitosan solution and stirring the mixture at room temperature for 0.5 to 3 hours to obtain a phosphorylated chitosan slurry;

[0042] The concentration of phosphoric acid in the phosphoric acid solution is 75% to 85%.

[0043] Preferably, step S3 includes: diluting the phosphorylated chitosan slurry with deionized water by 3 to 5 times, then immersing the PP cotton fiber in the diluted phosphorylated chitosan slurry, ultrasonically treating it for 6 to 15 minutes at a power of 40 kHz, then allowing it to stand and soak for 6 to 24 hours, removing it and placing it in a weak alkaline solution for curing, and then removing it and placing it in a ventilated and cool place to dry, thereby obtaining the modified PP cotton fiber material.

[0044] Preferably, in step S3, in order to ensure that the PP cotton fiber pores are quickly and evenly wetted by the phosphorylated chitosan slurry, the ultrasonic treatment time is set to 10 minutes.

[0045] Preferably, in step S3, the addition ratio of PP cotton fiber to phosphorylated chitosan slurry is 2-10 cm⁻¹. 3 100mL.

[0046] Preferably, the soaking and curing time is 4 to 12 hours.

[0047] By soaking in alkaline conditions, the phosphorylated chitosan slurry impregnated on the surface of PP cotton fibers is cured, which increases the adhesion of the phosphorylated chitosan slurry to the surface of PP cotton fibers, thereby effectively enhancing the hydraulic stability of this active layer.

[0048] The present invention also provides an application of the pre-filtered fiber modified material prepared by the preparation method described in the present invention, wherein the pre-filtered fiber modified material is used in an aqueous solution containing heavy metals.

[0049] Preferably, the pre-filtered fiber modified material is used as a heavy metal adsorbent in aqueous solutions containing heavy metals.

[0050] Preferably, the pre-filtered fiber modified material can still adsorb heavy metals in the aqueous solution after adsorption and regeneration, thus realizing the recycling of the pre-filtered fiber modified material.

[0051] Preferably, the heavy metal includes at least one of cadmium, nickel, copper, lead, and mercury.

[0052] The present invention also provides an application of the PP cotton fiber modified material prepared by the preparation method described in the present invention, wherein the PP cotton fiber modified material is used in an aqueous solution containing heavy metals.

[0053] Preferably, the PP cotton fiber modified material is used as a heavy metal adsorbent in aqueous solutions containing heavy metals.

[0054] Preferably, the PP cotton fiber modified material can still adsorb heavy metals in the aqueous solution after adsorption and regeneration, thus realizing the recycling of the PP cotton fiber modified material.

[0055] Preferably, nitric acid and / or EDTA solution is used to regenerate the PP cotton fiber modified material after adsorbing heavy metals.

[0056] Preferably, the heavy metal is at least one of divalent cadmium ions, divalent nickel ions, divalent copper ions, divalent lead ions, and divalent mercury ions.

[0057] The beneficial effects of this invention are:

[0058] 1) The pre-filter fiber modified material of the present invention, by loading phosphoric acid adhesive material onto the pre-filter fiber, enhances the binding force of the adhesive material to heavy metals in water with phosphoric acid, thereby effectively enhancing the adsorption stability of the pre-filter fiber. The introduction of phosphoric acid adhesive material increases the specific surface area of ​​the pre-filter fiber, making the pre-filter fiber modified material have a higher adsorption capacity. Experiments have shown that the pre-filter fiber modified material has good adsorption performance in the pH range of 4 to 10. The adsorption performance is less affected by common coexisting anions in water, which improves the adaptability of the pre-filter fiber modified material. At the same time, the adsorption rate is higher than 80% after 3 or more cycles of adsorption and regeneration, showing good cycle regeneration performance. Therefore, using the pre-filter fiber modified material as a pre-treatment material for the filter membrane effectively plays the role of moving the gate forward.

[0059] 2) The preparation method of the pre-filter fiber modified material of the present invention involves placing phosphoric acid in an adhesive aqueous solution to phosphorylate the adhesive material, thereby effectively enhancing the binding force of the adhesive material to heavy metals in water. Then, the pre-filter fiber is immersed in the phosphorylated adhesive material slurry to modify the pre-filter fiber, thereby effectively increasing the adsorption performance and environmental adaptability of the pre-filter fiber. At the same time, the phosphorylated adhesive material increases the specific surface area of ​​the pre-filter fiber, thereby effectively improving the adsorption capacity of the pre-filter fiber. Moreover, the preparation method has the advantages of simple operation, mild conditions and low cost, and has potential application value in the field of water treatment technology. Attached Figure Description

[0060] Figure 1 The infrared spectra of the PP cotton fiber modified material prepared in Example 1 of the present invention, the conventional PP cotton fiber prepared in Comparative Example 1, and chitosan are shown.

[0061] Figure 2 SEM images of the modified PP cotton fiber material prepared in Example 1 of the present invention and the conventional PP cotton fiber prepared in Comparative Example 1.

[0062] Figure 3 The modified PP cotton fiber material prepared in Example 1 of this invention has a positive effect on Cd in aqueous solutions with different pH values. 2+ The removal rate results;

[0063] Figure 4 The modified PP cotton fiber materials prepared in Examples 1 to 3 of this invention, as well as the unmodified PP cotton fiber in Comparative Example 1 and the chitosan-loaded modified PP cotton fiber prepared in Comparative Example 2, are used to evaluate the effect of Cd in aqueous solution. 2+ The removal rate results;

[0064] Figure 5The PP cotton fiber modified material prepared in Example 1 of this invention has a positive effect on Cd in an aqueous solution containing coexisting anions. 2+ The removal rate results;

[0065] Figure 6 The PP cotton fiber modified material prepared in Example 1 of this invention adsorbs Cd. 2+ Fitting curves of Langmuir and Freundlich adsorption isotherm models;

[0066] Figure 7 The results show the regeneration adsorption performance of the PP cotton fiber modified material obtained in Example 1 of this invention.

[0067] Figure 8 The results show the adsorption performance of the PP cotton fiber modified material prepared in Example 1 of this invention for different heavy metal ions. Detailed Implementation

[0068] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0069] Example 1

[0070] A method for preparing a PP cotton fiber modified material includes the following steps:

[0071] S1. Dissolving chitosan in an organic acid solution to obtain a chitosan solution, specifically including:

[0072] S11. Pretreatment: Cut the purchased PP cotton fiber cloth into several 30mm×50mm rectangular pieces, soak them in 15% nitric acid at 80℃ for 24 hours, then remove them and rinse the PP cotton fiber cloth with a large amount of deionized water until the washing solution is neutral; then place the PP cotton fiber cloth in an oven and dry it at 120℃ for 6 hours; then collect it and store it in a desiccator for later use. Through the above pretreatment process, ensure that organic matter and residual volatile substances in the pores of the PP cotton fiber are completely removed;

[0073] S12. Weigh 5g of chitosan powder into a beaker and add 100mL of 2% acetic acid solution. Stir mechanically at 300rpm for 2h to ensure complete dissolution and obtain a uniform, yellowish-brown, viscous, gel-like chitosan solution.

[0074] S2. Adding the phosphoric acid solution to the chitosan solution to form a phosphorylated chitosan slurry, specifically including:

[0075] Add 10 mL of 30% phosphoric acid solution to the chitosan solution obtained in S12, and continue stirring the reaction at room temperature for 30 min. At this time, the viscous solution turns into a light yellow color, which is the phosphorylated chitosan slurry.

[0076] S3. Immerse the PP cotton fibers in the phosphorylated chitosan slurry, remove them, and then solidify them in a weak alkaline solution to obtain the PP cotton fiber modified material, specifically including:

[0077] S31. Take 30 mL of the phosphorylated chitosan slurry obtained in S2 and dilute it 5 times with deionized water to obtain the diluted phosphorylated chitosan slurry.

[0078] S32, The volume is 3cm 3 The pretreated rectangular pieces of PP cotton fiber cloth in S11 are placed in the diluted phosphorylated chitosan slurry in S31 and ultrasonically treated for 10 minutes at a power of 40 kHz. Then, they are left to stand and soak for 24 hours before the rectangular pieces of PP cotton fiber cloth are taken out.

[0079] S33. Place the rectangular pieces of PP cotton fiber cloth taken out in S32 into a 3% ammonia solution and immerse them for 6 hours to complete the curing. Then wash them with deionized water until neutral and let them air dry naturally to complete the load modification treatment and obtain the PP cotton fiber modified material.

[0080] Example 2

[0081] A method for preparing a PP cotton fiber modified material includes the following steps:

[0082] S1. Dissolving chitosan in an organic acid solution to obtain a chitosan solution, specifically including:

[0083] S11. Pretreatment: Cut the purchased PP cotton fiber cloth into several 30mm×50mm rectangular pieces, soak them in 15% nitric acid at 80℃ for 24 hours, then remove them and rinse the PP cotton fiber cloth with a large amount of deionized water until the washing solution is neutral; then place the PP cotton fiber cloth in an oven and dry it at 120℃ for 6 hours; then collect it and store it in a desiccator for later use. Through the above pretreatment process, ensure that organic matter and residual volatile substances in the pores of the PP cotton fiber are completely removed;

[0084] S12. Weigh 5g of chitosan powder into a beaker and add 100mL of 2% acetic acid solution. Stir mechanically at 300rpm for 2h to ensure complete dissolution and obtain a uniform, yellowish-brown, viscous, gel-like chitosan solution.

[0085] S2. Adding the phosphoric acid solution to the chitosan solution to form a phosphorylated chitosan slurry, specifically including:

[0086] Add 5 mL of 30% phosphoric acid solution to the chitosan solution obtained in S12, and continue stirring at room temperature for 30 min. At this time, the viscous solution turns into a light yellow color, which is the phosphorylated chitosan slurry.

[0087] S3. Immerse the PP cotton fibers in the phosphorylated chitosan slurry, remove them, and then solidify them in a weak alkaline solution to obtain the PP cotton fiber modified material, specifically including:

[0088] S31. Take 30 mL of the phosphorylated chitosan slurry obtained in S2 and dilute it 5 times with deionized water to obtain the diluted phosphorylated chitosan slurry.

[0089] S32, The volume is 3cm 3 The pretreated rectangular pieces of PP cotton fiber cloth in S11 are placed in the diluted phosphorylated chitosan slurry in S31 and ultrasonically treated for 10 minutes at a power of 40 kHz. Then, they are left to stand and soak for 24 hours before the rectangular pieces of PP cotton fiber cloth are taken out.

[0090] S33. Place the rectangular pieces of PP cotton fiber cloth taken out in S32 into a 3% ammonia solution and immerse them for 6 hours to complete the curing. Then wash them with deionized water until neutral and let them air dry naturally to complete the load modification treatment and obtain the PP cotton fiber modified material.

[0091] Example 3

[0092] A method for preparing a PP cotton fiber modified material includes the following steps:

[0093] S1. Dissolving chitosan in an organic acid solution to obtain a chitosan solution, specifically including:

[0094] S11. Pretreatment: Cut the purchased PP cotton fiber cloth into several 30mm×50mm rectangular pieces, soak them in 15% nitric acid at 80℃ for 24 hours, then remove them and rinse the PP cotton fiber cloth with a large amount of deionized water until the washing solution is neutral; then place the PP cotton fiber cloth in an oven and dry it at 120℃ for 6 hours; then collect it and store it in a desiccator for later use. Through the above pretreatment process, ensure that organic matter and residual volatile substances in the pores of the PP cotton fiber are completely removed;

[0095] S12. Weigh 5g of chitosan powder into a beaker and add 100mL of 2% acetic acid solution. Stir mechanically at 300rpm for 2h to ensure complete dissolution and obtain a uniform, yellowish-brown, viscous, gel-like chitosan solution.

[0096] S2. Adding the phosphoric acid solution to the chitosan solution to form a phosphorylated chitosan slurry, specifically including:

[0097] Add 15 mL of 30% phosphoric acid solution to the chitosan solution obtained in S12, and continue stirring at room temperature for 30 min. At this time, the viscous solution turns pale yellow, which is the phosphorylated chitosan slurry.

[0098] S3. Immerse the PP cotton fibers in the phosphorylated chitosan slurry, remove them, and then solidify them in a weak alkaline solution to obtain the PP cotton fiber modified material, specifically including:

[0099] S31. Take 30 mL of the phosphorylated chitosan slurry obtained in S2 and dilute it 5 times with deionized water to obtain the diluted phosphorylated chitosan slurry.

[0100] S32, The volume is 3cm 3 The pretreated rectangular pieces of PP cotton fiber cloth in S11 are placed in the diluted phosphorylated chitosan slurry in S31 and ultrasonically treated for 10 minutes at a power of 40 kHz. Then, they are left to stand and soak for 24 hours before the rectangular pieces of PP cotton fiber cloth are taken out.

[0101] S33. Place the rectangular pieces of PP cotton fiber cloth taken out in S32 into a 3% ammonia solution and immerse them for 6 hours to complete the curing. Then wash them with deionized water until neutral and let them air dry naturally to complete the load modification treatment and obtain the PP cotton fiber modified material.

[0102] Comparative Example 1

[0103] A method for preparing conventional PP cotton fiber material includes the following steps:

[0104] The purchased PP cotton fiber cloth was cut into several 30mm×50mm rectangular pieces, soaked in 15% nitric acid at 80℃ for 24 hours, then removed and rinsed with a large amount of deionized water until the washing liquid was neutral; then the PP cotton fiber cloth was placed in an oven and dried at 120℃ for 6 hours; then it was collected and stored in a desiccator for later use, thus obtaining conventional PP cotton fiber material.

[0105] Comparative Example 2

[0106] A method for preparing chitosan-loaded modified PP cotton fiber material includes the following steps:

[0107] S1. Dissolving chitosan in an organic acid solution to obtain a chitosan solution, specifically including:

[0108] S11. Pretreatment: Cut the purchased PP cotton fiber cloth into several 30mm×50mm rectangular pieces, soak them in 15% nitric acid at 80℃ for 24 hours, then remove them and rinse the PP cotton fiber cloth with a large amount of deionized water until the washing solution is neutral; then place the PP cotton fiber cloth in an oven and dry it at 120℃ for 6 hours; then collect it and store it in a desiccator for later use. Through the above pretreatment process, ensure that organic matter and residual volatile substances in the pores of the PP cotton fiber are completely removed;

[0109] S12. Weigh 5g of chitosan powder into a beaker and add 100mL of 2% acetic acid solution. Stir mechanically at 300rpm for 2h to ensure complete dissolution and obtain a uniform, yellowish-brown, viscous, gel-like chitosan solution.

[0110] S2. Immerse the PP cotton fibers in the chitosan slurry, remove them, and then solidify them in a weak alkaline solution to obtain a PP cotton fiber modified material, specifically including:

[0111] S21. Take 30 mL of the chitosan solution obtained in S1 and dilute it 5 times with deionized water to obtain the diluted chitosan solution.

[0112] S22, The volume is 3cm 3 The rectangular pieces of PP cotton fiber cloth pretreated in S11 were placed in the diluted chitosan solution in S31, ultrasonically treated for 10 minutes, and then allowed to stand and soak for 24 hours before taking out the rectangular pieces of PP cotton fiber cloth.

[0113] S23. Place the rectangular pieces of PP cotton fiber cloth taken out in step 22 into a 3% ammonia solution and immerse them for 6 hours to complete the curing. Then wash them with deionized water until neutral and air dry them naturally to complete the load modification treatment and obtain chitosan-load-modified PP cotton fiber material.

[0114] Detection and Analysis

[0115] 1) Infrared spectroscopy test

[0116] The modified PP cotton fiber material prepared in Example 1, the conventional PP cotton fiber material in Control Example 1, and chitosan powder were subjected to infrared spectroscopy tests. The infrared spectroscopy test conditions were: ATR diffuse reflectance mode, wavenumber set to 400–4000 cm⁻¹. -1 The results were obtained using a Thermo Fisher Scientific Nicolet IS50 Fourier transform infrared spectrometer. Figure 1 As shown.

[0117] Figure 1 After loading, the material represents the modified PP cotton fiber prepared in Example 1; before loading, the material represents conventional PP cotton fiber; and chitosan represents chitosan powder. Figure 1Comparative analysis revealed that the modified PP cotton fiber material after load modification (i.e., the modified PP cotton fiber material prepared in Example 1) exhibited typical infrared absorption characteristics of chitosan functional groups. Specifically, at 3100 cm⁻¹... -1 ~3500cm -1 The broad absorption band is characterized by the stretching vibrations of the two hydroxyl groups, C2-NH2(NH) and C3-OH and C6-OH, of the chitosan dangling amino group; 1500 cm⁻¹ -1 ~1700cm -1 The absorption band between [a certain point] is the bending vibration peak of the amino group; while at 850 cm⁻¹... -1 ~1200cm -1 The absorption bands that appear are absorption peaks of oxyglycosidic bonds. Furthermore, due to the pre-phosphorylation treatment before loading, the loaded PP cotton fiber fabric still exhibits absorption peaks at 1205 cm⁻¹. -1 An additional absorption peak was observed, which is precisely the characteristic peak of the stretching vibration of the triple degeneracy of phosphate groups. The appearance of these characteristic peaks and absorption bands indicates that the modification treatment method designed in this study is reasonable and successfully introduces a phosphorylated chitosan active layer onto PP cotton fiber cloth.

[0118] 2) Scanning electron microscopy analysis

[0119] The modified PP cotton fiber material prepared in Example 1 and the conventional PP cotton fiber material in Control Example 1 were characterized by scanning electron microscopy. The results are as follows: Figure 2 As shown.

[0120] Figure 2 In the text, "before loading" represents conventional PP cotton fiber material, and "after loading" represents the PP cotton fiber modified material prepared in Example 1. Figure 2 Analysis revealed that the PP cotton fiber cloth treated with phosphorylated chitosan (i.e., the PP cotton fiber modified material prepared in Example 1) showed some residual film-like deposits between the disordered stacked fibers compared to the unloaded material (the conventional PP cotton fiber material obtained in Example 1). These deposits were the cured phosphorylated chitosan. At a magnification of 400x, it was observed that the phosphorylated chitosan cured with ammonia alkaline solution adhered to each PP cotton fiber bundle, while some extended into films connecting adjacent fiber bundles. These inter-bundle films reduced the stacked porosity of the fibers, potentially leading to higher interception efficiency when treating water with excessive turbidity. At an even higher magnification of 4000x, it was found that the surface of the attached phosphorylated chitosan active film layer was rougher than the relatively smooth surface of the original fiber filaments, effectively increasing the specific surface area of ​​the material and demonstrating that the PP cotton fiber modified material possesses a higher adsorption capacity.

[0121] 3) Heavy metal removal rate test

[0122] The 3cm sample obtained in Example 1 3 PP cotton fiber modified material was placed in solutions containing Cd(II) (i.e., Cd) at different pH values. 2+ In an aqueous solution containing 20 mg / L Cd(II), adsorption was performed by shaking at 350 rpm in a constant-temperature cyclotron shaker at 30°C. Samples were taken every 30 minutes using a syringe, and the Cd(II) content in the aqueous solution was analyzed by ICP-OES. After 240 minutes, the Cd(II) content in the aqueous solution was... 2+ The removal rate results are as follows Figure 3 As shown.

[0123] from Figure 3 Analysis shows that the adsorption and removal rate of Cd(II) in water by the PP cotton fiber modified material prepared in Example 1 shows an overall trend of first increasing and then decreasing with the pH of the solution between 3 and 10. The removal rate is relatively stable between pH 4 and 10, and is always higher than 90%, thus proving that the PP cotton fiber modified material of the present invention has a wide pH adaptability.

[0124] The 3cm samples obtained in Examples 1 to 3 were respectively... 3 PP cotton fiber modified material, and the unmodified 3cm material in Control Example 1. 3 PP cotton fiber and 3cm in control example 2 3 Chitosan-loaded modified PP cotton fiber material was placed in a solution containing Cd(II) (i.e., Cd). 2+ In an aqueous solution containing 20 mg / L Cd(II), adsorption was performed by shaking at 350 rpm in a constant-temperature cyclotron shaker at 30°C. Samples were taken every 30 minutes using a syringe, and the Cd(II) content in the aqueous solution was analyzed by ICP-OES. After 240 minutes, the Cd(II) content in the aqueous solution was... 2+ The removal rate results are as follows Figure 4 As shown.

[0125] from Figure 4Analysis shows that plain PP cotton fiber, i.e., Control Example 1, has almost no adsorption and removal capacity for Cd(II). After loading chitosan onto the PP cotton fiber, i.e., the chitosan-modified PP cotton fiber material prepared in Control Example 2, it possesses a certain Cd(II) adsorption efficiency. When the loading material is changed to phosphorylated chitosan, i.e., the Cd(II) adsorption efficiency of the PP cotton fiber modified materials prepared in Examples 1 to 3 is significantly improved, with adsorption removal rates all exceeding 50%. This proves that the present invention increases the adsorption sites through phosphorylation treatment of chitosan, which is beneficial to enhancing the binding capacity of chitosan to Cd(II). Comparative analysis of the PP cotton fiber modified materials prepared with different amounts of phosphoric acid (i.e., the PP cotton fiber modified materials obtained in Examples 1, 2, and 3) reveals that excessive phosphoric acid addition leads to a decrease in adsorption effect; the optimal amount is 10 mL.

[0126] The 3cm sample obtained in Example 1 3 PP cotton fiber modified material is placed in a solution containing different concentrations of coexisting anions (specifically, as shown in the image). Figure 5 The Cd(II) (i.e., Cd shown) 2+ In an aqueous solution containing 20 mg / L Cd(II), adsorption was performed by shaking at 350 rpm in a constant-temperature cyclotron shaker at 30°C. Samples were drawn every 30 minutes using a syringe, and the Cd(II) content was analyzed using ICP-OES. After 240 minutes, the Cd(II) concentration in the aqueous solution was [data missing]. 2+ The removal rate results are as follows Figure 5 As shown.

[0127] from Figure 5 Analysis revealed that the presence of chloride (sodium chloride) and sulfate (sodium sulfate) had no significant effect on the adsorption efficiency; the presence of nitrate (sodium nitrate) promoted the adsorption of Cd(II); while the presence of bicarbonate (sodium bicarbonate) and phosphate (disodium hydrogen phosphate) significantly inhibited the adsorption process. This demonstrates that, in practical applications, the PP cotton fiber modified material of this invention can be used to adsorb Cd(II) from solutions containing chloride (sodium chloride) and sulfate (sodium sulfate). 2+ The removal of nitrates (sodium nitrate) can further promote the adsorption of Cd(II) by PP cotton fiber modified materials. At the same time, attention should be paid to the content of phosphates (disodium hydrogen phosphate) and the alkalinity of bicarbonates (sodium bicarbonate) in the water to avoid affecting the adsorption performance of PP cotton fiber modified materials for Cd(II).

[0128] 4) Adsorption isotherm test

[0129] The PP cotton fiber modified material prepared in Example 1 was subjected to Cd(II) (i.e., Cd) in water. 2+ The adsorption isotherm experiment of ) and the fitting results of the Langmuir and Freundlich isotherm adsorption models are as follows: Figure 6 As shown in Table 1.

[0130] Table 1 Fitting parameters for Langmuir and Freundlich adsorption isotherm models

[0131]

[0132] from Figure 6 As can be seen from the comprehensive analysis in Table 1, the correlation coefficient R obtained by the Langmuir isothermal adsorption model is... 2 The higher value demonstrates that the adsorption process of Cd(II) on phosphorylated chitosan-modified PP cotton fibers is more consistent with the Langmuir isotherm adsorption model, indicating that the adsorption sites of Cd(II) on the phosphorylated chitosan activated layer are independent. Furthermore, the maximum theoretical Cd(II) adsorption capacity q of the PP cotton fiber modified material is significantly higher. m The concentration is 19.23 mg / g, which is ideal.

[0133] 5) Adsorption-regeneration test

[0134] The PP cotton fiber modified material prepared in Example 1 was subjected to Cd(II) (i.e., Cd) in water. 2+ After the adsorption experiment, the material was removed and eluent was prepared using a mixed solution of 0.5% nitric acid and / or 0.1 mol / L EDTA. The phosphorylated chitosan-modified PP cotton fiber cloth, saturated with adsorption, was immersed in the eluent and placed in a rotary shaker at 300 rpm at room temperature for 8 hours. Afterward, it was removed and repeatedly washed with deionized water until neutral to complete regeneration. The Cd(II) adsorption experiment in water was then performed again, and the above steps were repeated once more. The same material underwent two regenerations. In all three adsorption experiments, the Cd(II) concentration in the aqueous solution was 20 mg / L. The adsorption efficiency results for the three experiments are as follows: Figure 7 As shown.

[0135] from Figure 7 Comparative analysis shows that the mixed solution of nitric acid and EDTA is the best choice for regenerator. When using this mixed solution for regeneration, the adsorption capacity of the regenerated PP cotton fiber modified material is significantly improved. After three regeneration treatments, the average adsorption rate is still higher than 80%, thus proving that the PP cotton fiber modified material prepared by this invention has excellent regeneration performance.

[0136] 6) Adsorption performance test of different heavy metals

[0137] The 3cm sample obtained in Example 13 PP cotton fiber modified materials were placed in a solution of Cd with an initial ion concentration of 20 mg / L. 2+ Cu 2+ Pb 2+ Hg 2+ Ni 2+ Hg was placed in an aqueous solution and oscillated at 350 rpm in a constant-temperature cyclotron shaker at a temperature of 30°C. 2+ Adsorption was performed, and samples were drawn every 30 minutes using a syringe. The heavy metal ion content in the samples was analyzed using ICP-OES. The adsorption and removal efficiency of the material for each heavy metal within 240 minutes was calculated (expressed as concentration at sampling time / initial concentration, C / C0). Figure 8 As shown.

[0138] from Figure 8 Analysis shows that phosphorylated chitosan-loaded PP cotton fibers, i.e., the PP cotton fiber modified material prepared in Example 1, are effective for Cd(II)(Cd 2+ Cu(II)(Cu) 2+ ), Pb(II)(Pb 2+ ), Hg(II)(Hg 2+ ) and Ni(II)(Ni 2+ The five divalent heavy metal ions in the water all showed good adsorption and removal effects, with removal rates exceeding 90% within 3 hours, thus proving that the pre-filter fiber modified new material proposed in this invention is suitable for the removal of multiple heavy metals in water.

[0139] In summary, the PP cotton fiber modified material of this invention, by loading phosphorylated chitosan onto PP cotton fibers, enhances the binding force of chitosan to heavy metals in water through phosphoric acid, thereby effectively improving the adsorption stability of PP cotton fibers. Furthermore, the introduction of phosphorylated chitosan increases the specific surface area of ​​PP cotton fibers, resulting in a higher adsorption capacity. Experiments have demonstrated that the PP cotton fiber modified material exhibits good adsorption performance within a pH range of 4–10, with minimal impact from commonly coexisting anions in water, thus improving its adaptability. Simultaneously, after three or more cycles of adsorption and regeneration, the adsorption rate exceeds 80%, demonstrating excellent regeneration performance. Therefore, using the PP cotton fiber modified material as a pretreatment material for filters effectively shifts the treatment process upstream.

[0140] The present invention discloses a method for preparing modified PP cotton fiber materials. This method involves placing phosphoric acid in a chitosan solution to phosphorylate the chitosan, effectively enhancing the binding force of chitosan to heavy metals in water. Then, the PP cotton fiber is immersed in the phosphorylated chitosan solution to modify the PP cotton fiber, thereby effectively increasing its adsorption performance and environmental adaptability. Simultaneously, the phosphorylated chitosan increases the specific surface area of ​​the PP cotton fiber, thus effectively improving its adsorption capacity. Furthermore, the preparation method has the advantages of simple operation, mild conditions, and low cost, and has potential application value in the field of water treatment technology.

[0141] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A method for preparing a pre-filtered fiber modified material, characterized in that, Includes the following steps: S1. Dissolve the adhesive material in an organic acid solution to obtain an adhesive aqueous solution; S2. Add the phosphoric acid solution to the adhesive aqueous solution to obtain a phosphorylated adhesive slurry; S3. The pre-filtration fiber before the water treatment membrane is immersed in the phosphoric acid adhesive slurry, and then placed in a weak alkaline solution for immersion and curing to obtain a modified pre-filtration fiber material, including the pre-filtration fiber before the water treatment membrane and the phosphoric acid adhesive material loaded on the pre-filtration fiber before the water treatment membrane. The modification of the pre-filtration fiber before the water treatment membrane is achieved through the phosphoric acid adhesive material.

2. The method for preparing the pre-filtered fiber modified material according to claim 1, characterized in that, The pre-filtration fiber before the water treatment membrane is selected from PP cotton fiber and / or activated carbon; And / or the adhesive material in the phosphorylated adhesive material is selected from at least one of chitosan, carrageenan and sodium alginate.

3. The method for preparing the pre-filtered fiber modified material according to claim 1, characterized in that, In S1, the solid-liquid ratio of the adhesive material to the organic acid solution is 1g~10g:100mL.

4. The method for preparing the pre-filtered fiber modified material according to claim 3, characterized in that, The organic acid solution is at least one of formic acid solution, acetic acid solution and propionic acid solution; And / or the volume concentration of the organic acid in the organic acid solution is 1% to 3%.

5. The method for preparing the pre-filtered fiber modified material according to claim 1, characterized in that, The solid-liquid ratio of the adhesive material to the phosphoric acid solution is 1g~10g:0.5~2.5mL.

6. The method for preparing the pre-filtered fiber modified material according to claim 1, characterized in that, S2 includes: adding a phosphoric acid solution to the adhesive aqueous solution and reacting at room temperature for 0.5 to 3 hours to obtain a phosphoric acid adhesive slurry; The concentration of phosphoric acid in the phosphoric acid solution is 75%~85%; And / or S3 includes: diluting the phosphoric acid adhesive slurry 3 to 5 times with water, then immersing the pre-filtered fiber before the water treatment membrane in the diluted phosphoric acid chitosan slurry, ultrasonically treating it for 6 to 15 minutes, then letting it stand and soak for 6 to 24 hours, taking it out and placing it in a weak alkaline solution for curing, to obtain the pre-filtered fiber modified material.

7. The method for preparing the pre-filtered fiber modified material according to claim 6, characterized in that, In step S3, the addition ratio of the pre-filtration fiber before the water treatment membrane to the diluted phosphoric acid adhesive slurry is 2~10 cm. 3 100mL; And / or the weak alkaline solution is an ammonia solution, with an ammonia concentration of 3% to 9%; And / or the soaking and curing time is 4~12h.

8. The application of a pre-filtered fiber modified material prepared by the preparation method according to any one of claims 1 to 7, characterized in that, Application of the pre-filtered fiber-modified material in aqueous solutions containing heavy metals.

9. The application according to claim 8, characterized in that, The pre-filtered fiber modified material is used as an adsorbent for heavy metals in aqueous solutions containing heavy metals; and / or the pre-filtered fiber modified material can still adsorb heavy metals in aqueous solutions after adsorption and regeneration, realizing the recycling of the pre-filtered fiber modified material; and / or the heavy metals include at least one of cadmium, nickel, copper, lead and mercury.

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