CN111111480B

CN111111480B - Zoledronic acid modified nanofiltration membrane and preparation method thereof

Info

Publication number: CN111111480B
Application number: CN202010020357.1A
Authority: CN
Inventors: 孙世鹏; 曹雪丽; 蔡静; 柏勇; 周富毅; 赵燚
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2020-01-09
Filing date: 2020-01-09
Publication date: 2021-09-14
Anticipated expiration: 2040-01-09
Also published as: CN111111480A

Abstract

The invention relates to a zoledronic acid modified nanofiltration membrane and a preparation method thereof, belonging to the technical field of preparation of separation membrane materials. Asymmetric Zoledronic Acid (ZA) is used for nanofiltration membrane modification, and a defective pore channel is generated in a novel nanofiltration membrane due to the asymmetry of ZA and the imidazole group which does not participate in the interface reaction, so that the water flux of the nanofiltration membrane is improved by nearly 6 times while the high salt rejection rate of the nanofiltration membrane is kept, and the modified nanofiltration membrane shows perfect Na₂SO₄And NaCl, and has extremely strong anti-pollution performance to organic pollutants (bovine serum albumin). In addition, the membrane has high interception and pollution resistance to the sodium salt of tiger red in the aqueous solution, which shows that the prepared nanofiltration membrane has great application potential in the field of high pollution.

Description

Zoledronic acid modified nanofiltration membrane and preparation method thereof

Technical Field

The invention relates to a zoledronic acid modified nanofiltration membrane and a preparation method thereof, belonging to the technical field of preparation of separation membrane materials.

Background

Nanofiltration (NF) is a novel membrane separation technology with the aperture between reverse osmosis and ultrafiltration, which is developed in the later 80 s of the 20 th century, the aperture of the membrane is about 0.5-2nm, the technology is suitable for separating molecules of 200-. However, the two common problems of the "trade-off" effect between the permeability and the selectivity of the nanofiltration membrane and the easy pollution of the membrane are always significant problems for limiting the development and even industrialization of the nanofiltration membrane.

For selectivity to meet the requirements of the application, higher permeability means lower energy consumption, higher efficiency. For membrane elements, a high fouling resistant membrane material means a longer service life, lower industrial cost investment and higher enterprise profits. Therefore, the efficient development of an anti-fouling high-permeability nanofiltration membrane is a technical difficulty which must be overcome in the development of the current nanofiltration membrane.

Disclosure of Invention

The purpose of the invention is: in order to improve the permeability, interception performance and pollution resistance of the nanofiltration membrane material, the invention adopts the zoledronic acid modified nanofiltration membrane.

A zoledronic acid modified nanofiltration membrane comprises a base layer and a selective separation layer, wherein zoledronic acid is also added into the selective separation layer.

In one embodiment, the selective separation layer is obtained by interfacial polymerization of piperazine monomers and acid chloride monomers.

The preparation method of the zoledronic acid modified nanofiltration membrane comprises the following steps:

step 1, providing a base film;

step 2, preparing an aqueous solution containing a first monomer and zoledronic acid as a water phase; preparing an organic solution containing a second monomer as an organic phase; the first monomer is capable of undergoing an interfacial polymerization reaction with the second monomer;

and 3, applying a water phase on the surface layer of the base membrane, and then applying an organic phase to perform interfacial polymerization reaction to obtain the modified nanofiltration membrane.

In one embodiment, the first monomer is a piperazine-based monomer and the second monomer is an acid chloride-based monomer.

In one embodiment, the organic solution may be n-hexane.

In one embodiment, the concentration of the first monomer in the aqueous phase may be 0.1 to 5wt%, the concentration of the zoledronic acid in the aqueous phase may be 0.1 to 5wt%, and the concentration of the second monomer in the organic phase may be 0.05 to 0.5 wt%.

In one embodiment, the concentration of the first monomer in the aqueous phase is preferably 0.6wt% and the concentration of zoledronic acid in the aqueous phase is preferably 1.4 wt%; the concentration of the second monomer in the organic phase is preferably 0.1% by weight.

The nanofiltration membrane is applied to liquid filtration.

In one embodiment, the liquid filtration refers to filtration of an aqueous solution containing organic matter or filtration of an aqueous solution of inorganic salts.

The application of zoledronic acid in preparing nanofiltration membrane.

In one embodiment, the zoledronic acid is used to increase the pure water flux of the nanofiltration membrane, increase porosity, reduce surface roughness, reduce the thickness of the selective separation layer of the nanofiltration membrane, loosen the structure of the surface of the selective separation layer, resist organic contamination, or increase the flux recovery rate of the nanofiltration membrane after cleaning.

A method for regulating and controlling the molecular weight cut-off of a nanofiltration membrane comprises the following steps: the molecular weight cut-off of the nanofiltration membrane is improved by adding zoledronic acid into a selective separation layer of the nanofiltration membrane.

Advantageous effects

According to the invention, the asymmetric organic phosphoric acid is utilized, the hydrophilicity of the membrane is improved, a polymer network pore canal with a larger size and a defective solvent channel are constructed in the membrane structure by utilizing the larger volume of the asymmetric organic phosphoric acid and the imidazolyl group which does not participate in the interface reaction, the pure water flux of the membrane is greatly improved, and meanwhile, the phosphoric acid contributes to the negative electricity of the surface of the membrane, so that the membrane shows perfect separation performance of sodium sulfate and sodium chloride. In addition, the flat and hydrophilic membrane surface shows excellent anti-pollution performance in an inorganic salt system, an organic pollutant system and a dye system.

Drawings

FIG. 1 is a SEM representation picture of the surface and section of the prepared nanofiltration membrane, and an AFM representation picture of the surface;

figure 2 is a contact angle comparison of the nanofiltration membranes prepared.

FIG. 3 is a Zeta potential diagram of the nanofiltration membrane prepared.

Figure 4 is a molecular weight cut-off curve of the nanofiltration membrane prepared.

Figure 5 is a comparison of the water flux of the nanofiltration membrane prepared and the retention effect on magnesium sulfate.

Figure 6 is inorganic salt rejection data for the nanofiltration membranes prepared.

Fig. 7 is an anti-pollution characterization experiment of the prepared nanofiltration membrane.

Figure 8 is a dye retention characterization experiment of the nanofiltration membrane prepared.

Figure 9 is a comparison of water flux and magnesium sulfate rejection of nanofiltration membranes obtained by the one-step process and the surface grafting process.

Table 1 compares the separation performance of the modified membranes prepared against monovalent and divalent salts with other commercial membranes and with those reported in the literature

Detailed Description

The present invention will be described in further detail with reference to the following embodiments. It will be understood by those skilled in the art that the following examples are illustrative of the present invention only and should not be taken as limiting the scope of the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

The words "include," "have," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

The percentages recited in the present invention refer to mass percentages unless otherwise specified.

The invention relates to a zoledronic acid modified nanofiltration membrane and a preparation method thereof. In the present invention, asymmetric oxazoles are usedPhosphonic acid (ZA) is used for carrying out nanofiltration membrane modification, and due to the asymmetry of ZA and the imidazolyl which does not participate in interface reaction, a defective pore channel is generated in the novel nanofiltration membrane, so that the water flux of the nanofiltration membrane is improved by nearly 6 times while the high salt rejection rate of the nanofiltration membrane is kept, and the modified nanofiltration membrane shows perfect Na₂SO₄And NaCl, and has extremely strong anti-pollution performance to organic pollutants (bovine serum albumin). In addition, the membrane has high interception and pollution resistance to the sodium salt of tiger red in the aqueous solution, which shows that the prepared nanofiltration membrane has great application potential in the field of high pollution.

The nanofiltration membrane provided by the invention is formed by compounding a base membrane and a selective separation layer based on zoledronic acid modification.

The base membrane used therein may be an appropriate ultrafiltration membrane selected according to the actual circumstances, for example: polyimide (PI), Polyethersulfone (PES), Sulfonated Polysulfone (SPSF), Polyetherimide (PEI), and the like. The preparation process of the base membrane mainly comprises the steps of mixing corresponding polymer particles and a solvent to obtain a membrane casting solution, then blade-coating the membrane casting solution on non-woven fabrics, and preparing the porous asymmetric base membrane by a phase inversion method.

Selecting a separation layer to prepare on the surface of a basement membrane through an interfacial polymerization method, wherein the preparation process comprises the steps of preparing an aqueous phase solution and an organic phase solution, and adding piperazine monomers and zoledronic acid into the aqueous phase solution; the organic phase solution is mainly an organic solution of acyl chloride monomer, such as trimesoyl chloride in n-hexane. The concentration of the piperazine monomer aqueous solution is 0.1-5wt%, the concentration of the zoledronic acid in the aqueous solution can be 0.1-5wt%, and the concentration of the acyl chloride monomer n-hexane solution is 0.05-0.5 wt%.

The prepared organic phosphoric acid modified membrane has larger pore canal, higher porosity, more negative surface electrical property, more hydrophilic and smoother surface for the unmodified traditional nanofiltration membrane, has very high interception rate for divalent negative ions, and has lower interception rate for monovalent negative ions, so the prepared modified nanofiltration membrane has good effect on the separation of sulfate radical and chloride ion, and shows the anti-pollution performance under various conditions.

Example 1

Preparation of a base film: firstly, polyamide high polymer materials are dried in vacuum for 24 hours, then dissolved in an organic solvent, stirred for 24 hours by using a cantilever stirrer, and kept stand for 12 hours for defoaming. And (3) coating the casting film liquid on non-woven fabrics fixed on a glass plate by using a scraper, then quickly immersing the non-woven fabrics in water for phase change and film formation, and storing the prepared flat membrane in deionized water to obtain the polyamide base membrane.

Preparation of selective separation layer: preparing an aqueous solution of m wt% of piperazine (PIP) and n wt% of Zoledronic Acid (ZA) as an aqueous phase solution of interfacial polymerization, wherein the dissolving of ZA is realized by regulating and controlling pH value, and preparing a 0.1wt% of trimesoyl chloride n-hexane solution as an organic phase solution of interfacial polymerization, wherein the trimesoyl chloride solution needs to be stirred until the trimesoyl chloride is completely dissolved and then used. Pouring the aqueous phase solution on a membrane, standing for two minutes to remove excessive water, pouring the aqueous phase solution into an organic phase, reacting for 1 minute to remove excessive solution on the surface, and carrying out one-step interfacial polymerization on a base membrane to prepare the modified membrane. The resulting film was stored in deionized water until use.

The prepared membrane was named M-mP/nZ, M represents PIP concentration, P represents piperazine, n represents ZA depth, and Z represents zoledronic acid.

Comparative example 1

The difference from example 1 is that no zoledronic acid was added to the aqueous solution.

The preparation process of the base film is the same.

The selective separation layer was prepared by: preparing 2wt% of piperazine (PIP) aqueous solution as an aqueous phase solution of interfacial polymerization, preparing 0.1wt% of trimesoyl chloride n-hexane solution as an organic phase solution of interfacial polymerization, wherein the trimesoyl chloride solution is used after being stirred to be completely dissolved. Pouring the aqueous phase solution on the membrane, standing for two minutes to remove excessive water, pouring the aqueous phase solution into the organic phase, reacting for 1 minute to remove the excessive solution on the surface, and storing the obtained membrane in deionized water for use.

The membrane prepared by the method is named as M-2.0P.

Comparative example 2

The difference from example 1 is that: the zoledronic acid modifier is added after the selective separation layer is prepared.

The preparation process of the base film is the same.

Preparing an aqueous solution containing m% of PIP, preparing an aqueous solution containing n% of ZA (in the period, the dissolving of ZA is realized by regulating and controlling pH), then carrying out interfacial polymerization of PIP and TMC on a base membrane, removing redundant solution, pouring the aqueous solution containing n% of ZA, reacting for two minutes, carrying out surface grafting, removing redundant solution, and obtaining the modified membrane through two-step interfacial polymerization. The membrane prepared in this control example was designated as M-mP-nZ membrane.

Characterization of the membranes

Characterization of SEM and AFM

Different concentrations of ZA and PIP in the aqueous phase will cause the modified membrane to exhibit different structural morphologies (fig. 1). First, the membrane surface exhibited a pronounced nodular structure, indicating the success of the interfacial polymerization process. As ZA concentrations increase from 0.0 to 1.8 wt% and PIP concentrations decrease from 2.0 to 0.2 wt%, nodules become smaller and smaller, primarily due to the hindrance of large size PIP-ZA diffusion from the aqueous to organic phase. Compared with M-0.6P/1.4Z, the preparation process of M-0.2P/1.8Z has poor crosslinking degree due to too low PIP-ZA concentration, and shows loose nodular structure. In addition, SEM characterization of the cross-sections shows that the selective layer becomes progressively thinner with increasing ZA concentration, since the degree of crosslinking is increasingly lower and PIP-ZA at the oil-water interface is difficult to diffuse (fig. 1). AFM characterization also showed that the film surface was gradually smoothed, while M-0.6P/1.4Z was the most smooth (Ra =9.7 nm), while the surface roughness value for the unmodified M-2.0P nanofiltration membrane was Ra =38.4 nm; therefore, the smoother membrane surface can effectively avoid the deposition of pollutants in the filtering process, so the nanofiltration membrane obtained by the method can effectively improve the smoothness of the membrane surface and reduce the formation of membrane surface pollution in the filtering process; it can also be seen in the figure that M-0.2P/1.8Z shows a slightly increased roughness (Ra = 11.3) of M-0.6P/1.4Z. This anomaly may be due to the low PIP content in M-0.2P/1.8Z, the small number and size of PIP-ZA due to competitive effects, and the greater ease of diffusion in the interface, resulting in a surface roughness slightly higher for M-0.2P/1.8Z than for M-0.6P/1.4Z. SEM and AFM characteristics show that M-0.6P/1.4Z shows a thin, smooth and loose membrane structure, and indicates high permeability and antifouling performance of the modified membrane; therefore, compared with the M-2.0P nanofiltration membrane which is not modified by zoledronic acid, the thickness of the selective separation layer can be remarkably reduced, the roughness of the selective separation layer can be reduced, and the nodular structure on the surface of the selective separation layer can be looser after the one-step modification by ZA.

Characterization of contact angle, Zeta potential, molecular weight cut-off

As shown in fig. 2, the contact angle (WCA) measurement results showed that the WCA had a gradually decreasing trend with increasing ZA concentration and increasing number of phosphoric acid groups in the modified film, indicating that the hydrophilicity was gradually increased. While as the ZA concentration continued to rise, the WCA of the M-0.2P/1.8Z film appeared to rise due to: although the concentration of ZA in the aqueous phase for preparing M-0.2P/1.8Z membranes is highest, ZA is only a modifier and not a monomer directly participating in the crosslinking reaction; PIP, as a ligand directly involved in interfacial polymerization, is present in very low concentrations (0.2 wt%) in the aqueous phase of M-0.2P/1.8Z preparations, thus resulting in a very low amount of PIP-ZA in the crosslinked film; therefore, the contact angle of M-0.2P/1.8Z is slightly higher than that of the M-0.6P/1.4Z film. Finally, the contact angle test results confirm the positive contribution of ZA to the hydrophilicity of the membrane.

As shown in fig. 3, in the aqueous phase, different PIP and ZA ratios result in the resulting film exhibiting different surface electrical properties. First, M-2.0P exhibits electronegativity, but its electronegativity is the weakest, since TMC is in excess compared to PIP, and the excess acid chloride on TMC is hydrolyzed to carboxyl groups. As the ZA concentration increases, the PIP concentration decreases and the film shows increasingly more electronegativity, mainly because there is less PIP contributing positively to the film, while there is an increasing ZA showing negative. Thus, the M-0.6P/1.4Z membrane exhibited very strong electronegativity. Paradoxically, M-0.2P/1.8Z exhibited a general electronegativity, a cause similar to that of the abnormality in hydrophilicity of the M-0.2P/1.8Z membrane. In summary, potential testing of the membrane indicated that the modification of ZA resulted in a strongly electronegative NF membrane.

As shown in fig. 4, different PIP and ZA ratios result in the resulting membrane exhibiting different membrane pore sizes. Since only PIP can react directly with TMC to obtain a cross-linked structure, the pores on the membrane should become larger and larger as the PIP concentration decreases. The results of the molecular weight cut-off (MWCO) test show that as the PIP concentration decreases, MWCO increases from 255D to 475 Da, showing an increasingly loose membrane structure, while also indicating that all membranes are NF membranes.

Characterization of Permeability

Through the characteristics, the ZA modified membrane has a looser, thinner and more hydrophilic structure, and enlarged polyamide network pore channels and defect pore channels induced by imidazole sites which do not participate in the reaction, which indicates that the modified membrane may have higher permeability. Pure Water Permeability (PWP) test results show that as ZA concentration increases from 0 to 1.8 wt%, PIP concentration decreases from 2.0 to 0.2 wt%, PWP increases from 5.70 to 40.5L ∙ m^-2bar^-1h^-1(FIG. 5). Permeability tests confirmed that the introduction of ZA greatly improved the permeability of the nanofiltration membranes.

Retention test for inorganic salt

Figure 5 shows that NF membranes prepared from different concentrations of aqueous solutions exhibit different rejection rates for magnesium sulfate. The selectivity of the membrane necessarily decreases with increasing permeability due to the "trade-off" effect. As can be seen from the graph, MgSO increased as the ZA content increased to 1.0 wt.%₄The rejection rate of the catalyst is obviously reduced; the rejection rate continues to decrease with increasing ZA content. Finally, the M-0.6P/1.4Z membrane exhibited the best performance (pure water permeability of 29.0L ∙ M^-2bar^-1h^-1，MgSO₄The rejection of (c) was 89.2%), because: (1) the M-0.6P/1.4Z membrane has a thin selection layer, enlarged polyamide network pore channels, defect pore channels and a hydrophilic membrane surface; (2) M-0.6P/1.4Z shows extremely strong surface electronegativity. Therefore, we chose M-0.6P/1.4Z as representative of ZA-modified membranes.

Different fromSelectivity test of organic salts

The best performing ZA modified membrane M-0.6P/1.4Z was selected and tested for retention to different single salt solutions (zones a and b in fig. 6). The results show that the rejection order of the membrane for the different mono-salts is: na (Na)₂SO₄ > MgSO₄ > MgCl₂ >NaCl, description of ZA modified Membrane on divalent anion SO₄ ^2-Has high retention rate to monovalent Cl^-The rejection performance is low, which is achieved by the cooperative regulation of pore size sieving and charge repulsion. This indicates that ZA modified membranes have good potential to separate monovalent and divalent anions.

Therefore, we tested M-0.6P/1.4Z for Na at various concentrations₂SO₄And NaCl mixed solution and selectivity to monovalent and divalent ions at different operating pressures (regions c and d of fig. 6). Membrane to SO under different operating conditions₄ ^2-The retention of (C) is always higher than 91.6% for Cl^-The rejection of ZA was consistently below-29.6%, indicating that ZA-modified membranes are sensitive to SO under various operating conditions₄ ^2-And Cl^-Has high selective separation. Definition of membrane pair SO₄ ^2-And Cl^-Has a separability of S (SO)₄ ^2-/Cl^-)= R/ SO₄ ^2--R/Cl^-Table 1 shows the ratio of M-0.6P/1.4Z to SO₄ ^2-And Cl^-Compared with other commercial membranes or literature-reported membranes, M-0.6P/1.4Z has the highest permeability and exhibits the optimal SO₄ ^2-And Cl^-This means a great potential for the use of modified membranes in the chlor-alkali industry, water softening and other separations.

TABLE 1

Wherein S is selectivity, and as can be seen from the table, in addition to being compared with the M-2.0P unmodified membrane in the invention, the modified nanofiltration membrane prepared by the invention also shows selective separation performance on sulfate and chloride ions which is far higher than that of the nanofiltration membrane in the prior art.

Reference to the literature

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Anti-pollution performance

The antifouling property of the membrane is also the necessary quality for the membrane to be applied in many fields, and the good antifouling property can prolong the service life and the replacement period of the membrane component, thereby reducing the investment cost of enterprises. We performed antifouling performance tests on M-0.6P/1.4Z membranes using aqueous BSA as the feed solution. For comparison and evaluation of antifouling properties, an antifouling test was conducted simultaneously for M-0.6P/1.4Z, M-0.6P and M-2.0P (FIG. 7). We evaluated the anti-fouling performance of the membranes by the flux reduction rate during the test and the flux recovery rate after the cleaning. For the M-0.6P/1.4Z membrane, the flux decreased only 9.9% in the first filtration cycle, while the M-0.6P membrane compared therewith reached 55.7% in the first filtration cycle. After pure water washing, the flux recovery rate of M-0.6P/1.4Z reaches 95.2%, while the flux recovery rate of the M-0.6P membrane is only 22.8% compared with the flux recovery rate, and the flux still shows a continuous descending trend in the washing process. The result is also shown mutually with the AFM characterization result, which proves that the nanofiltration membrane treated by ZA modification can effectively show the pollution resistance in the filtration process of protein solution, and the flux can be recovered by flushing after the filtration due to higher surface smoothness, thereby improving the easy cleaning property. The results show that: (1) M-0.6P/1.4Z and M-2.0P show higher anti-pollution performance; (2) M-0.6P has poor antifouling property; (3) the flux of M-0.6P/1.4Z is much higher than that of M-2.0P. The reason is that: (1) the M-0.6P/1.4Z membrane has hydrophilic and smooth surfaces and loose and defective pore channels; (2) the larger pore size of M-0.6P is easily blocked by BSA molecules. The anti-pollution performance test shows that M-0.6P/1.4Z has higher flux and stronger anti-pollution performance, so the modified membrane has greater application potential.

Meanwhile, the interception performance and the anti-pollution performance of the ZA modified membrane in the highly-polluted dye industry are tested (figure 8), and the membrane is found to intercept molecules with the molecular weight of more than 400 Da and show stronger anti-pollution performance to the sodium salt of tiger red, so that the application prospect of M-0.6P/1.4Z in the highly-polluted dye industry is shown.

Comparison of Performance of one-step interfacial polymerization method and surface grafting method for preparing films

The ZA-modified film obtained by the one-step interfacial polymerization method in example 1 was seen to exhibit excellent properties, and the difference in properties between the modified film obtained by film surface grafting of ZA in comparative example 2 was further compared below.

The ZA modified membrane prepared by the surface grafting method is marked as M-0.6P-1.4Z, and the test result shows that the permeability of the ZA modified membrane is the same as that of the ZA modified membrane prepared by the surface grafting method, but the ZA modified membrane is MgSO 2₄The retention rate is obviously higher than that of an M-0.6P membrane; while the permeability of M-0.6P/1.4Z is 3 times that of M-0.6P and M-0.6P-1.4Z, while maintaining a very high MgSO₄Retention rate (area a of fig. 9). The reason for the analysis is as follows: (1) the lower the PIP content in the interfacial polymerization process, the looser the membrane structure, so the permeability of M-0.6P is higher than that of M-2.0P; (2) ZA surface grafting does not radically change the density of the membrane, so that the permeability is not improved compared with M-0.6P, but the electronegativity of M-0.6P-1.4Z is obviously enhanced due to the modification of phosphate groups, so that MgSO is MgSO₄The retention rate is obviously higher than that of the M-0.6P membrane, and meanwhile, the successful grafting of ZA on the surface of the membrane is also shown; (3) the permeability of the M-0.6P/1.4Z membrane obtained by one-step interfacial polymerization method is greatly improved, and MgSO₄There was no significant reduction in retention, mainly because the addition of ZA resulted in a loose, defective cell structure and the strongest surface electronegativity. We compared the stability of ZA-modified membranes prepared by different methods and the results show that both ZA-modified membranes prepared by the two methods have very good stability (b in fig. 9). Comprehensive analysis, and one-step interfacial polymerization is an effective method for constructing an ideal ZA modified membrane.

Claims

1. The zoledronic acid modified nanofiltration membrane is characterized by comprising a base layer and a selective separation layer, wherein zoledronic acid is also added into the selective separation layer;

step 1, providing a base film;

step 2, preparing an aqueous solution containing a first monomer and zoledronic acid as a water phase; preparing an organic solution containing a second monomer as an organic phase;

step 3, applying a water phase on the surface layer of the base film, and then applying an organic phase to perform interfacial polymerization reaction to obtain the zoledronic acid modified nanofiltration membrane;

the first monomer is piperazine, and the second monomer is trimesoyl chloride.

2. The zoledronic acid modified nanofiltration membrane according to claim 1, wherein the organic solution is n-hexane.

3. The method for preparing a zoledronic acid modified nanofiltration membrane according to claim 1, wherein the concentration of the first monomer in the aqueous phase is 0.1-5wt%, the concentration of the zoledronic acid in the aqueous phase is 0.1-5wt%, and the concentration of the second monomer in the organic phase is 0.05-0.5 wt%.

4. Use of the zoledronic acid modified nanofiltration membrane of claim 1 in liquid filtration.

5. Use according to claim 4, wherein the liquid filtration is filtration of an aqueous solution containing organic matter or filtration of an aqueous solution containing inorganic salts.