Modified fiber filter cloth and application thereof in heavy metal ion adsorption

Abstract

The application discloses modified fiber filter cloth and application thereof in heavy metal ion adsorption. Through dicyandiamide etching and bridging effect of arginine, a stable polyphenol hydroxyl adsorption layer is formed on the surface of the polyester fiber, the chelating capacity of the modified polyester fiber to heavy metal ions is effectively improved, and the modified polyester fiber has excellent adsorption performance in treatment of heavy metal ions in textile wastewater, especially has high efficient removal effect on Cu 2+ , Zn 2+ and the like in the textile wastewater. The modification method provides a new solution for efficient and environment-friendly textile wastewater treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of environmental pollution control and functional materials, in particular to textile wastewater treatment. Specifically, it is a modified fiber filter cloth and its application in heavy metal ion adsorption. BACKGROUND

[0002] The textile industry produces a large amount of wastewater in the production process, which contains various pollutants, especially heavy metal ions (such as copper, chromium, nickel, etc.). These heavy metal ions are difficult to degrade and have biological accumulation, and can be transmitted through the food chain after entering the water body, posing a serious threat to the ecological environment and human health. If the textile wastewater contaminated by heavy metals is not effectively treated, it will cause long-term harm to water resources and the environment. Therefore, developing efficient heavy metal ion removal technology has become an important issue in textile wastewater treatment.

[0003] The current common method for removing heavy metal ions includes chemical precipitation, ion exchange, membrane separation and adsorption. Among them, the adsorption method is widely used in heavy metal wastewater treatment due to its high efficiency, low cost and simple operation. Traditional adsorption materials such as activated carbon and natural minerals have certain adsorption capacity, but often have limited adsorption capacity and cannot meet the needs of large-scale treatment. Therefore, developing efficient functional adsorption materials has become a research hotspot.

[0004] Fiber rotating disc filter is a high-efficiency and low-energy consumption solid-liquid separation equipment, which is widely used in municipal sewage, industrial wastewater and water reuse treatment fields. Its main function is to intercept suspended particles, colloids and part of dissolved pollutants in water through high-precision fiber filter cloth, thereby achieving deep purification. The equipment uses fiber filter cloth as the filter medium, and relies on the rotation and backwashing technology of the filter disc to ensure the continuity and efficiency of filtration. Compared with traditional heavy metal removal methods such as chemical precipitation, ion exchange and activated carbon adsorption, the fiber rotating disc filter has the following advantages: compact equipment structure, small footprint, high treatment efficiency, simple operation and maintenance, and low energy consumption.

[0005] Polyester fiber rotating disc filter cloth as the core component is mainly used for removing suspended solids, silt, microorganisms and part of organic pollutants in water. However, although polyester fiber has excellent mechanical properties such as high strength and wear resistance, and good chemical stability, it can resist acid and alkali and various chemicals, but its surface chemical activity is low. This leads to limited adsorption capacity of polyester fiber for heavy metal ions, especially when directly treating wastewater containing heavy metals, the removal effect may be insufficient. In order to improve the adsorption performance of polyester fiber, surface modification is usually needed, such as introducing functional groups or compounding with high adsorption materials, to give it stronger heavy metal capture ability, so as to expand its application range and further improve the sewage treatment effect. Polyphenolic compounds, especially tannic acid (TA), can form stable chelates with heavy metal ions due to the presence of multiple phenolic hydroxyl groups in the molecule, making it an ideal adsorbent. TA can effectively remove metal ions from water through coordination with heavy metal ions. Studies have shown that TA has good chelation effect on various heavy metal ions (such as Cu2+, Zn2+, Pb 2 +). Therefore, TA-based modified materials have significant effect in removing heavy metal ions in textile wastewater, and have the advantages of green environmental protection, easy availability, etc. The prior art directly soaks nanofibers in a TA aqueous solution for modification, but the tannic acid loading and adhesion stability of the modified fibers prepared by this method are not very ideal and need to be further improved. SUMMARY

[0006] The present application aims to modify polyester fiber filter cloth with tannic acid (TA) to improve its heavy metal ion adsorption capacity and provide an efficient and environmentally friendly solution for textile wastewater treatment.

[0007] The present application is achieved by the following technical solutions:

[0008] The first object of the present application is to provide a modified fiber filter cloth comprising polyester fiber and tannic acid loaded on the surface of the polyester fiber; the polyester fiber is pre-etched on the surface with dicyandiamide; and the tannic acid is loaded on the surface of the polyester fiber with arginine bridging agent.

[0009] In an embodiment of the present application, surface etching with dicyandiamide includes the following steps:

[0010] The polyester fiber is placed in a 2-5% dicyandiamide solution, treated with NaOH as catalyst at 60-100°C water bath for 10-30 minutes.

[0011] In an embodiment of the present application, loading tannic acid on the surface of the polyester fiber includes the following steps:

[0012] S01, the surface etched terylene fiber is immersed in an arginine solution, and is oscillated and treated under alkaline conditions for 2-4 hours, is taken out, washed and dried after treatment, and arginine treated terylene fiber is obtained;

[0013] S02, the arginine treated terylene fiber is immersed in a tannic acid solution, and is oscillated and treated under acidic conditions for 1-8 hours, is taken out, washed and dried after treatment, and tannic acid loaded terylene fiber is obtained.

[0014] In an embodiment of the present application, the concentration of the arginine solution is 4-6 mg / ml.

[0015] In an embodiment of the present application, the concentration of the tannic acid solution is 2-4 mg / ml.

[0016] A second object of the present application is to provide a preparation method of the modified fiber filter cloth, comprising the following steps:

[0017] S1, the terylene fiber is placed in a 2-5% dicyandiamide solution, and is treated under the condition of a 60-100℃ water bath for 10-30 minutes with NaOH as a catalyst;

[0018] S2, the surface etched terylene fiber is immersed in an arginine solution, and is oscillated and treated under alkaline conditions, is taken out, washed and dried after treatment, and arginine treated terylene fiber is obtained;

[0019] S3, the arginine treated terylene fiber is immersed in a tannic acid solution, and is oscillated and treated under acidic conditions, is taken out, washed and dried after treatment, and the modified fiber filter cloth is obtained.

[0020] In an embodiment of the present application, the concentration of the arginine solution is 4-6 mg / ml.

[0021] In an embodiment of the present application, the treatment time in S2 step is 2-4 h.

[0022] In an embodiment of the present application, the concentration of the tannic acid solution is 2-4 mg / ml.

[0023] In an embodiment of the present application, the treatment time in S3 step is 1-8 h.

[0024] In an embodiment of the present application, the treatment time in S3 step is 1-2 h.

[0025] A third object of the present application is to provide the application of the modified fiber filter cloth in sewage treatment.

[0026] A fourth object of the present application is to provide the application of the modified fiber filter cloth in heavy metal ion adsorption.

[0027] The beneficial effects of the present application are:

[0028] The present application can effectively improve the surface activity of polyester fibers by etching the surface of polyester fibers with dicyandiamide. The amino group in dicyandiamide can react with the surface of polyester fibers, destroying part of the molecular structure of the fibers and forming a porous structure to increase the specific surface area. This etching makes the surface of polyester fibers have more adsorption sites, providing a good foundation for subsequent functional modification. Under the etching action of dicyandiamide, various active groups are formed on the surface of polyester fibers, which provides attachment sites for subsequent TA loading, thereby improving the adsorption performance of heavy metal ions.

[0029] To further improve the loading amount and binding stability of tannic acid on the surface of polyester fibers, L-arginine is used as a bridging agent. The molecular structure of L-arginine contains guanidino and carboxyl groups, which can be combined with the surface of etched polyester fibers through hydrogen bonding or electrostatic interaction, and also interact with the phenolic hydroxyl groups in tannic acid molecules, enhancing the stability of their attachment. The introduction of L-arginine not only increases the loading amount of tannic acid, but also provides additional adsorption sites, significantly improving the heavy metal ion removal efficiency of the adsorption material.

[0030] Through the etching of dicyandiamide and the bridging action of L-arginine, a stable polyphenol hydroxyl adsorption layer is formed on the surface of polyester fibers, effectively improving their chelating ability for heavy metal ions. The modified polyester fibers exhibit excellent adsorption performance in the treatment of heavy metal ions in textile wastewater, especially for the efficient removal of Cu2+ and Zn2+ ions in textile wastewater. This modification method provides a new solution for efficient and environmentally friendly textile wastewater treatment. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0032] Figure 1 is the modification mechanism diagram of the polyester filter cloth of the present application.

[0033] Figure 2 is the change diagram of water contact angle of the polyester filter cloth before and after modification of the present application.

[0034] Figure 3 is the time variation of TA loading on PET, PET / APTES, PET / PEI and PET / L-Arg of the present application.

[0035] Figure 4 Absorbance curve of TA released from the PET / TA and PET / L-Arg / TA nanofiber pad of the present application in deionized water at 292 nm

[0036] Figure 5 Cu adsorption isotherm of the PET filter cloth of the present application 2+ Adsorption related experiments.

[0037] Figure 6 XPS element spectrum of the PET filter cloth of the present application before and after modification and the change of group energy before and after adsorption.

[0038] Figure 7 Schematic diagram of selective adsorption of the PET filter cloth of the present application before and after modification to Cu 2+

[0039] Figure 8 Cycling performance of the PET filter cloth of the present application DETAILED DESCRIPTION

[0040] The present application will be further described in conjunction with specific examples. These examples are only used to illustrate the present application and not intended to limit the scope of the present application. Furthermore, after reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope of the appended claims of the present application.

[0041] Raw material sources

[0042] The technical solutions of the present application will be described in detail in conjunction with specific examples. In the following examples, unless otherwise specified, the reagents, materials and equipment used can be purchased from commercial channels, or prepared by conventional methods, or commonly used in the industry.

[0043] Example 1

[0044] A high-precision commercial long pile filter cloth with a model number of WL-102 was selected as the base material. The filter cloth material is polyester, and the pile length is 25 mm. The pretreatment process was completed by treating in a 2% dicyandiamide solution with NaOH as catalyst at 80°C water bath for 20 minutes.

[0045] The pretreated polyester filter cloth (size 2 cm x 2 cm x 1 cm) was placed in an arginine (5 mg / ml) solution, and the pH value of the solution was adjusted to 9.0 by 0.1M HCl / NaOH. After oscillation in a constant temperature oscillator at 25°C and 100 rpm for 2 hours, the sample was taken out, washed with deionized water for 3 times, and dried for 12 hours to obtain the sample PET / L-Arg.

[0046] ​The obtained PET / L-Arg was immersed in a TA solution (2 mg / ml) with a pH value of 4.0 adjusted by 0.1M HCl / NaOH, and was oscillated in a water bath at 25°C and 120 rpm for 0.5, 1, 1.5, and 2 hours, respectively. The sample was repeatedly washed with deionized water for 3 times, and was dried for 12 hours, to obtain PET / L-Arg / TA.

[0047] Example 2

[0048] A high-precision commercial long-pile filter cloth with a model number of WL-102 was selected as the base material, which was made of polyester and had a pile length of 25 mm. The pre-treatment process was completed by treating the filter cloth in a 5% dicyandiamide solution with NaOH as a catalyst at 80°C for 20 minutes.

[0049] The pre-treated polyester filter cloth (with a size of 2 cm x 2 cm x 1 cm) was placed in an arginine (5 mg / ml) solution with a pH value of 9.0 adjusted by 0.1M HCl / NaOH. After oscillation in a constant-temperature oscillator at 25°C and 100 rpm for 3 hours, the sample was washed with deionized water for 3 times, and was dried for 12 hours, to obtain the sample PET / L-Arg.

[0050] The obtained PET / L-Arg was immersed in a TA solution (2 mg / ml) with a pH value of 4.0 adjusted by 0.1M HCl / NaOH, and was oscillated in a water bath at 25°C and 120 rpm for 4 hours. The sample was repeatedly washed with deionized water for 3 times, and was dried for 12 hours, to obtain PET / L-Arg / TA.

[0051] Example 3

[0052] A high-precision commercial long-pile filter cloth with a model number of WL-102 was selected as the base material, which was made of polyester and had a pile length of 25 mm. The pre-treatment process was completed by treating the filter cloth in a 5% dicyandiamide solution with NaOH as a catalyst at 80°C for 20 minutes.

[0053] The pre-treated polyester filter cloth (with a size of 2 cm x 2 cm x 1 cm) was placed in an arginine (5 mg / ml) solution with a pH value of 9.0 adjusted by 0.1M HCl / NaOH. After oscillation in a constant-temperature oscillator at 25°C and 100 rpm for 2 hours, the sample was washed with deionized water for 3 times, and was dried for 12 hours, to obtain the sample PET / L-Arg.

[0054] The obtained PET / L-Arg was immersed in a TA solution (4 mg / ml) with pH value adjusted to 4.0 by 0.1 M HC1 / NaOH, and shaken in a water bath at 25 °C and 120 rpm for 5 h. The sample was taken out, washed repeatedly with deionized water for 3 times, and then dried for 12 h to obtain PET / L-Arg / TA.

[0055] Comparative Example 1

[0056] A high-precision commercial long-pile filter cloth with model number WL-102 was selected as the substrate, which was made of polyester with a pile length of 25 mm. The pre-treatment process was completed by treating the filter cloth in a 2% dicyandiamide solution with NaOH as the catalyst at 80 °C for 20 min.

[0057] The pre-treated polyester filter cloth (with a size of 2 cm x 2 cm x 1 cm) was placed in an aminopropyltriethoxysilane (APTES, 5 mg / ml) solution with pH value adjusted to 9.0 by 0.1 M HC1 / NaOH. After shaking in a constant temperature shaker at 25 °C and 100 rpm for 2 h, the sample was taken out, washed with deionized water for 3 times, and then dried for 12 h to obtain sample PET / APTES.

[0058] The obtained PET / APTES was immersed in a TA solution (2 mg / ml) with pH value adjusted to 4.0 by 0.1 M HC1 / NaOH, and shaken in a water bath at 25 °C and 120 rpm for 0.5, 1, 1.5, and 2 h, respectively. The sample was taken out, washed repeatedly with deionized water for 3 times, and then dried for 12 h to obtain PET / APTES / TA.

[0059] Comparative Example 2

[0060] A high-precision commercial long-pile filter cloth with model number WL-102 was selected as the substrate, which was made of polyester with a pile length of 25 mm. The pre-treatment process was completed by treating the filter cloth in a 2% dicyandiamide solution with NaOH as the catalyst at 80 °C for 20 min.

[0061] The pre-treated polyester filter cloth (with a size of 2 cm x 2 cm x 1 cm) was placed in a polyethyleneimine (PEI, 5 mg / ml) solution with pH value adjusted to 9.0 by 0.1 M HC1 / NaOH. After shaking in a constant temperature shaker at 25 °C and 100 rpm for 3 h, the sample was taken out, washed with deionized water for 3 times, and then dried for 12 h to obtain sample PET / PEI.

[0062] The obtained PET / PEI was immersed in a TA solution (2 mg / ml) with pH value adjusted to 4.0 by 0.1M HCl / NaOH, and shaken in a water bath at 25℃ and 120 rpm for 0.5, 1, 1.5 and 2 hours respectively. The sample was taken out, washed with deionized water for 3 times, and then dried for 12 hours to obtain PET / PEI / TA.

[0063] Comparative Example 3

[0064] A high-precision commercial long-pile velvet filter cloth with model WL-102 was selected as the base material, which was made of polyester and had a pile length of 25 mm. The pre-treatment process was completed by treating in a 2% dicyandiamide solution with NaOH as catalyst at 80℃ water bath for 20 minutes.

[0065] The PET was immersed in a TA solution (2 mg / ml) with pH value adjusted to 4.0 by 0.1M HCl / NaOH, and shaken in a water bath at 25℃ and 120 rpm for 0.5, 1, 1.5 and 2 hours respectively. The sample was taken out, washed with deionized water for 3 times, and then dried for 12 hours to obtain PET / TA.

[0066] Results and Tests

[0067] The performance of the samples was tested by the following tests.

[0068] Hydrophilicity test of fabric: Hydrophilicity is an important indicator for evaluating the performance of fabric. In this experiment, the water contact angle of the fabric was measured by POWER2000 large platform contact angle measuring instrument. The dry fabric was cut into a long strip and fixed on the experimental clamp. Under room temperature conditions, a drop of deionized water was dropped on the surface of the fabric sample on the shooting table, and the photo was taken. The data after the contact angle was stable was recorded and analyzed.

[0069] The change diagram of water contact angle of polyester filter cloth before and after modification is shown in Figure 2 As can be seen from the figure, after loading L-Arg, the contact angle rapidly decreases to 50.1° due to the hydrophilicity of L-Arg. With the deposition of TA and the formation of polyphenol coating, the contact angle decreases to a minimum of 39.3° after 1 hour. Exceeding this deposition time, a thick coating layer is formed on the surface, resulting in the gradual loss of fiber structure. Therefore, due to the decrease of surface roughness, the water contact angle increases, and the effect of the decrease of roughness exceeds the increase of hydrophilicity of the coating.

[0070] In order to verify the role of the bridging agent in enhancing the loading of TA on PET, ultraviolet spectrophotometry was used to measure the absorbance of the immersion solution and calculate the loading capacity of TA. Figure 3The time variation of TA loading on PET, PET / APTES, PET / PEI and PET / L-Arg was described. The results showed that L-Arg as a bridging agent significantly increased the loading capacity of TA compared with no bridging agent, APTES and PEI as bridging agents, and the total TA loading increased by 70%. This enhancement is due to the rich functional groups of L-Arg, which promote hydrogen bonding and other non-covalent interactions with ester groups in PET and phenolic hydroxyl groups in TA, thereby increasing the loading capacity of TA and having important significance for subsequent heavy metal adsorption experiments.

[0071] In order to evaluate the desorption performance of TA, 0.1 g of PET / TA1 and PET / L-Arg / TA n Nanofiber was immersed in 30 mL of deionized water (pH = 5). The temperature was controlled by a refrigerated circulator. At appropriate time intervals, the release medium was removed and the same volume of fresh medium at the same temperature was added. The concentration of TA in the release medium was determined by UV / visible spectroscopy at a wavelength of 292 nm. Figure 4 It was shown that TA was released in all samples. However, after the addition of L-Arg, PET / L-Arg / TA n The amount of TA released from the sample was significantly reduced. L-Arg interacts with tannic acid through non-covalent bonds such as hydrogen bonds, electrostatic interactions and π-π stacking through its amine and carboxyl functional groups, which helps to fix tannin more firmly on PET and reduces its tendency to decompose in water. The amine and carboxyl functional groups of L-Arg interact with TA through non-covalent interactions, which helps to fix tannin more firmly on PET and reduces its tendency to decompose in water. The amount of TA released gradually increased with the increase of the thickness of the double-layer film, indicating that L-Arg enhanced the stability of TA in water through strong non-covalent interactions, improving the recovery performance of the adsorbent.

[0072] XPS elemental analysis: XPS tests were performed on PET / L-Arg / TA before and after adsorbing copper ions using an X-ray photoelectron spectrometer of the model ESCALAB 250Xi from the American Thermo Scientific company. A monochromatic aluminum X-ray source (1486.6 eV) and a fixed pass energy (Retarding) mode were used. The charge correction was made with the C1s binding energy 284.8 eV as the standard. The surface element content was determined by the peak area ratio after correction with the sensitivity factor determined by experiment. The XPS element spectrum of the modified PET filter cloth and the change of the group bond energy before and after adsorption are shown in Figure 6 It can be seen that after adsorption, the signal of cu 2p appears in the full XPS spectrum, which is beneficial to prove that Cu 2+ has been successfully adsorbed on the adsorbent Figure 6 a). In addition, the state of copper is mainly Cu2+ exists in the form of Figure 6 As shown in b. Cu 2+ After adsorption, the CO / COC and CO peaks of O 1s shifted to 532.81 and 531.21 eV ( Figure 6 c), further indicating that oxygen-containing functional groups are involved in the adsorption process. In addition, due to the interaction between N atoms and Cu 2+ After sharing electrons, the electron density decreases, and the peaks of -CONH- and -NH2 shift to higher binding energies ( Figure 6 (d)

[0073] The concentrations of heavy metal ions in the solution were determined by atomic adsorption spectrometer (AA-240, Varian, USA).

[0074] Adsorption performance measurement: In order to study Cu 2+ In order to investigate the adsorption behavior of PET, PET / L-Arg and PET / L-Arg / TA fabrics, we conducted the following adsorption experiments. In general, 40 mL of copper sulfate (CuSO4-5H2O, Macklin) solution (Cu 2+ The concentration was 40-120 mg / L) and the adsorption was carried out under shaking at room temperature for 12 hours. The adsorbent was then collected and the Cu content in the filtrate was determined by atomic absorption spectrophotometry. 2+ The concentration of Cu on the adsorbent 2+ The adsorption amount was calculated according to the following formula.

[0075]

[0076]

[0077] Where, C0 (mg / L) is the initial Cu 2+ Concentration, C e (mg / L) is the equilibrium concentration after adsorption. t (mg / L) is the Cu content in the solution 2+ Real-time concentration. e (mg / g) and q t (mg / g) Cu 2+ The equilibrium adsorption capacity and real-time adsorption capacity of the adsorbent are shown in Table 1. M (g) is the amount of adsorbent used, and V (L) is the volume of the solution.

[0078] The effect of pH value (2.0-6.0) on the adsorption performance was evaluated by conducting adsorption experiments in a thermostatic shaker at 30°C, 120 rpm, and 12 hours. The pH value of the solution was adjusted with HCl (37%, Macklin) and NaOH (Macklin). 2+The adsorption capacity was tested at a concentration of 100 mg / L. The kinetic adsorption experiment was carried out at a pH of 5.0, a temperature of 30°C, and Cu 2+ The concentration was 40-120 mg / L.

[0079] The pH value of aqueous solution plays an important role in the adsorption of heavy metal ions because it may affect the surface functional groups of the adsorbent and the solution chemical properties of the pollutants. Therefore, we first investigated the effect of solution pH on the adsorption of Cu by PET / L-Arg / TA1. 2+ The effect of adsorption capacity, the results are as follows Figure 5 As shown in a. PET / L-Arg / TA1 to Cu 2+ The adsorption amount (qe) of Cu2+ increases with the increase of pH from 2 to 6, and the adsorption amount is the largest at pH = 6, which is 77.3 mg / g. This phenomenon is similar to that observed in the literature. Amine and -OH groups are easily protonated in strong acidic solutions, thereby inhibiting the adsorption of Cu2++. 2+ With the addition of H + With the decrease of concentration, the existing amine and -OH groups are beneficial to Cu 2+ Therefore, pH is positively correlated with the adsorption amount. However, when the solution pH is greater than 5, Cu 2+ Cu(OH)2 precipitate was generated. Therefore, in subsequent adsorption studies, the pH of the solution was set to 5.

[0080] In order to evaluate the effect of polyester filter cloth on Cu 2+ Ion adsorption properties of PET, PET / L-Arg and PET / L-Arg / TA n Tested. Figure 5 b is the Cu 2+ Comparison of adsorption performance. The adsorption capacity of PET is relatively low, at 21.4 mg / g, indicating that PET without chemical modification has a better adsorption capacity for Cu. 2+ The adsorption capacity of PET / L-Arg / TA1 was 77.5 mg / g, which was higher than 42.1 mg / g of PET / L-Arg. This indicates that the L-Arg bridging strategy enhanced the adsorption of Cu 2+ The results show that qe increases with the TA deposition time from 0.5 h to 1 h. This is because TA makes the fiber surface rougher, introducing more adsorption sites and improving the overall adsorption capacity. However, when the deposition time exceeds 1 h, the surface structure of the adsorbent transforms into a coating film, resulting in a decrease in active sites and a decrease in adsorption capacity.

[0081] In order to study the effect of PET / L-Arg / TA1 on the initial Cu 2+ The adsorption kinetics at different concentrations were studied, and the adsorption behavior, such as Figure 5As shown in c. Adsorption of Cu 2+ The amount of Cu increased rapidly at the beginning. Then the increasing trend weakened and eventually stabilized. This was due to the decrease in the number of effective binding sites. Therefore, 4h was finally selected as the 2+ The optimal time for adsorption experiment was investigated. 2+ The effect of concentration on adsorption capacity. Figure 5 As shown in Figure d, the adsorption capacity shows a trend that the initial copper ion concentration has a significant impact on the adsorption capacity. At low concentrations (40 mg / L), fewer ions are available, resulting in a decrease in adsorption capacity. As the concentration increases (60-80 mg / L), more adsorption sites are occupied, resulting in a greater adsorption capacity. At high concentrations (100-120 mg / L), the adsorption sites are saturated, and the adsorption capacity reaches a maximum value (68.5 mg / g). This relationship highlights the importance of initial concentration for optimizing heavy metal ion adsorption.

[0082] In order to investigate the adsorption selectivity, a multicomponent mixture (Cu 2+ 、Zn 2+ and Pb 2+ ) in competitive adsorption. The adsorbent was immersed in 40 mL of mixed metal ion solution and adsorbed at 25 ° C for 6 hours. The results are as follows Figure 7 As shown in the figure, it can be seen that the adsorption of these three ions by PET is very low, which is due to the lack of functional groups on the surface of the adsorbent that can chelate with heavy metal ions. In contrast, PET / L-Arg / TA1 has a low adsorption rate for Cu 2+ It exhibits high adsorption selectivity for Cu 2+ The adsorption capacity of Zn 2+ (23.3 mg / g) and Pb 2+ (16.9 mg / g) is 2.5-3.8 times the adsorption capacity. This selectivity may be related to the hydrated ion radius of the metal ion. Ions with smaller hydrated radii, such as Cu 2+ , it is easier to diffuse through the pores of the nanofiber membrane. This easy diffusion often leads to faster adsorption rate and higher adsorption capacity.

[0083] The reusability of PET / L-Arg / TA1 was tested. The recovered PET / L-Arg / TA1 was treated with EDTA solution (0.01 mol / L, 50 mL) for 2 h to remove the adsorbed Cu 2+ After washing with deionized water and drying, the regenerated PET / L-Arg / TA1 was used for the next adsorption run. Figure 8As shown, the results of 5 recycling experiments show that the first adsorption capacity is 70.3 mg / g, and the fifth adsorption capacity decreases to about 66.7 mg / g. The results show that the functional groups of PET / L-Arg / TA1 do not obviously separate during the desorption process, and the adsorption capacity is well maintained. Therefore, PET / L-Arg / TA1 has high adsorption capacity and good regeneration stability for Cu 2+ has high adsorption capacity and good regeneration stability.

[0084] The above provided examples are not intended to limit the scope of the present application, and the described steps are not intended to limit the execution order thereof. The improvements of the present application made by those skilled in the art in combination with the existing common knowledge are also within the protection scope defined by the claims of the present application.

Claims

1. A modified fiber filter cloth, characterized in that: The invention comprises a polyester fiber surface etched with dicyandiamide and tannic acid loaded on the surface of the polyester fiber; the tannic acid is loaded on the surface of the polyester fiber with an arginine bridging agent; Surface etching using dicyandiamide includes the following steps: Place the polyester fiber in a 2-5% dicyandiamide solution with NaOH as a catalyst and treat it in a water bath at 60-100°C for 10-30 minutes; Loading tannic acid on the surface of polyester fiber includes the following steps: S01, immersing the surface-etched polyester fiber in an arginine solution, shaking it under alkaline conditions for 2 to 4 hours, and then taking it out, washing it, and drying it to obtain an arginine-treated polyester fiber; S02. Immerse the arginine-treated polyester fiber in a tannic acid solution, shake it under acidic conditions for 1 to 8 hours, take it out after treatment, wash it, and dry it to obtain a tannic acid-loaded polyester fiber.

2. The method for preparing the modified fiber filter cloth according to claim 1, characterized in that: The steps include: S1. Place the polyester fiber in a 2-5% dicyandiamide solution with NaOH as a catalyst and treat in a water bath at 60-100°C for 10-30 minutes; S2, immersing the surface-etched polyester fiber in an arginine solution, shaking it under alkaline conditions, and then taking it out, washing it, and drying it to obtain an arginine-treated polyester fiber; S3, immersing the polyester fiber treated with arginine in a tannic acid solution, shaking the solution under acidic conditions, taking out the fiber after treatment, washing it, and drying it to obtain the modified fiber filter cloth.

3. The preparation method according to claim 2, characterized in that The concentration of the arginine solution is 4-6 mg / ml.

4. The preparation method according to claim 2, wherein The processing time in step S2 is 2 to 4 h.

5. The preparation method according to claim 2, wherein The concentration of the tannic acid solution is 2-4 mg / ml.

6. The preparation method according to claim 2, wherein The processing time in step S3 is 1 to 8 h.

7. Use of the modified fiber filter cloth according to claim 1 in sewage treatment.

8. Use of the modified fiber filter cloth according to claim 1 in heavy metal ion adsorption.

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