A titanium-based solid-phase filler and a titanium-based syringe filter containing the same and applications thereof

Abstract

The present invention discloses a titanium-based solid-phase filler, a titanium-based syringe filter containing the same, and applications thereof. The present invention utilizes the titanium-based solid-phase filler as a functional filler, filling it into a specially prepared titanium-based syringe filter for further selective processing of DOM samples pre-enriched by SPE. This design serves as a secondary selective purification step in the analytical process, efficiently removing background components of easily ionized carboxylic acids and phenolic oxygen-containing organic compounds, reducing mass spectrometry baseline noise, and significantly improving the detection sensitivity and quantitative reliability of soluble organic nitrogen compounds.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental functional materials and environmental detection, and in particular to a titanium-based solid-phase filler, a titanium-based syringe filter containing the same, and applications thereof. Background Art

[0002] Dissolved organic nitrogen compounds (DONs) are part of dissolved organic matter (DOM) in water. They are widely present in various environmental media, including surface water, groundwater, domestic sewage, and industrial wastewater, typically at low concentrations (ng / L-μg / L). Their sources include agricultural non-point source pollution, domestic sewage discharge, industrial wastewater discharge, and natural biological processes. They are a major pollutant that causes eutrophication and threatens drinking water safety.

[0003] DONs (DoNs) have diverse molecular structures, including amines, amides, nitrogen-containing heterocyclic compounds, amino acids, and their derivatives. These compounds are typically highly polar, making them difficult to detect directly using traditional liquid chromatography-mass spectrometry systems. Although ultrahigh-resolution mass spectrometry (e.g., FT-ICR MS and Orbitrap-MS) has been widely used in DOM research in recent years, the complex matrix and low target concentrations still require efficient sample pretreatment techniques for enrichment and purification. Currently, the most common pretreatment method utilizes solid-phase extraction (SPE), which primarily aims to enrich the entire DOM system rather than targeting the characteristic components of DONs. In particular, on commonly used packing materials such as PPL, HLB, and C18, oxygenated organic compounds such as carboxylic acids and phenols are primarily enriched. These compounds are not only abundant but also easily ionized by electrospray ionization (ESI), resulting in overly strong carboxylic acid signals during analysis, masking the mass spectrometric response of DONs.

[0004] Carboxylates are widely present in DOM, and their carboxyl groups can coordinate and adsorb to metal oxide surfaces. Studies have shown that the TiO2 surface is rich in Lewis acid sites, which can bind to carboxyl groups through monodentate or bidentate coordination, forming a stable Ti-OOC structure, thereby achieving highly selective adsorption of compounds containing carboxyl groups. This property can be used to selectively remove the highly interfering carboxyl background components in enriched DOM samples, thereby improving the signal-to-noise ratio and detection sensitivity of DONs in subsequent analyses.

[0005] Molecular sieve materials, particularly MCM-41 (Mobil Composition of Matter No. 41), with its regularly pore structure, are ideal support materials due to their high specific surface area, adjustable pore size, and surface modifiability. By in situ incorporating TiO2 into the pore structure of MCM-41, a TiO2 / MCM-41 composite molecular sieve material can be obtained. This material combines a controllable pore size distribution, good chemical affinity, and a stable interfacial structure, making it suitable for the selective adsorption and purification of carboxylic acid components in complex DOM background samples.

[0006] However, the selective adsorption capacity of molecular sieve materials in the existing technology for oxygen-containing organic compounds such as carboxylic acids and phenols still needs to be improved. They are unable to efficiently and selectively adsorb carboxylic acids and phenolic oxygen-containing organic compounds at the same time, resulting in insufficient detection sensitivity and quantitative reliability of soluble organic nitrogen compounds during the detection process.

[0007] Therefore, there is an urgent need for a titanium-based solid-phase filler and a titanium-based syringe filter containing the filler that can effectively and selectively adsorb carboxylic acids and phenolic oxygen-containing organic compounds, thereby improving the detection sensitivity and quantitative reliability of soluble organic nitrogen compounds. Summary of the Invention

[0008] Purpose of the invention: In view of the defects of the prior art, the purpose of the present invention is to provide a titanium-based solid-phase filler and a titanium-based syringe filter containing the same, and its application, which can effectively selectively adsorb carboxylic acids and phenolic oxygen-containing organic compounds, thereby improving the detection sensitivity and quantitative reliability of soluble organic nitrogen compounds.

[0009] Technical solution:

[0010] In one aspect, the present invention provides a titanium-based solid phase filler, which is prepared by the following steps:

[0011] (1) In a reactor, tetrabutyl titanate is mixed with dodecyltrimethylammonium bromide, ethyl orthosilicate, isopropyl alcohol, and ultrapure water. After sufficient stirring, a uniform sol is formed, and the pH value is adjusted with hydrochloric acid.

[0012] (2) Aging the prepared sol at a certain temperature to allow TiO2 to grow and crystallize in situ in the pore structure of MCM-41;

[0013] (3) After crystallization is completed, the unreacted template and impurities are removed by filtration and washing, and the template is removed after drying and calcination to obtain TiO2 / MCM-41 molecular sieve;

[0014] (4) adding TiO2 / MCM-41 molecular sieve and amino-modified silane into a reactor, heating and reacting after ultrasonic vibration, cooling, filtering, washing, and drying after the reaction is complete to obtain the titanium-based solid phase filler;

[0015] The amino-modified silane has a structure shown in the following formula A:

[0016] .

[0017] The titanium-based solid-phase filler in the present invention can accurately and efficiently selectively absorb carboxylic acid and phenolic oxygen-containing organic compounds. On the one hand, the TiO2 / MCM-41 molecular sieve filler can combine with the carboxylic acid functional groups through monodentate or bidentate coordination to form a stable Ti-OOC structure, thereby achieving highly selective adsorption of carboxyl functional group-containing compounds; on the other hand, by reacting amino-modified silane with TiO2 / MCM-41 molecular sieve, large steric hindrance and amino groups can be grafted on the molecular sieve, and phenolic oxygen anions can be electrostatically adsorbed after protonation of the amino group, and phenolic compounds can be selectively adsorbed through the benzene ring and the large steric hindrance structure.

[0018] Furthermore, in step (1), the molar ratio of tetrabutyl titanate, dodecyltrimethylammonium bromide, ethyl orthosilicate, isopropyl alcohol and ultrapure water is (0.1-0.5) : (0.1-0.3) : (0.5-2) : (1-3) : (2-5), and the pH of the sol is 2-4.

[0019] Furthermore, in step (2), the aging temperature is 100-150° C., and the aging time is 12-48 hours.

[0020] Furthermore, in step (3), the drying temperature is 80-120°C, and the drying time is 6-12 hours; the calcination temperature is 350-800°C, and the calcination time is 3-8 hours.

[0021] Furthermore, in step (4), the heating temperature is 110-130° C., and the reaction time is 4-6 h.

[0022] Furthermore, the amino-modified silane is prepared by the following steps: adding a solvent, diphenylchlorosilane and acrylamide into a reactor, heating to 40-50° C., adding a platinum catalyst, stirring and reacting for 3-4 hours, then heating to 55-60° C., adding dilute sulfuric acid and reacting for 2-3 hours, cooling, filtering, washing and drying to obtain the amino-modified silane.

[0023] Furthermore, the effective platinum content in the platinum catalyst is 1.0×10 -5 -5.0×l0 -5 The mass concentration of the dilute sulfuric acid is 15-25%; the molar ratio of diphenylchlorosilane to acrylamide is 1:1.2-1.5.

[0024] Another aspect of the present invention provides a titanium-based syringe filter, wherein the titanium-based syringe filter comprises any one of the titanium-based solid phase fillers described above;

[0025] The titanium-based syringe filter comprises a left-side liquid inlet port, a central main body shell, and a right-side tightening knob;

[0026] The titanium-based solid phase filler is filled in the central main body shell, and the filling amount is controlled to be 3-10 mg;

[0027] The titanium-based solid-phase filler has a pore size of 5-10 nm and an overall particle size of 100-200 nm.

[0028] The titanium-based syringe filter containing a titanium-based solid phase filler in the present invention has the advantages of being small, replaceable, highly adaptable, and suitable for rapid processing of small-volume samples compared to traditional column-type SPE materials. In addition, the titanium-based material filler proposed in the present invention has the characteristics of good thermal stability, high chemical tolerance, and strong selective adsorption, overcoming the problem that traditional filters only have physical filtration functions and cannot achieve chemical selective adsorption. It is particularly suitable for the pre-analysis treatment needs of trace DONs in high-throughput environmental samples.

[0029] Specifically, the filling amount can be 3, 4, 5, 6, 7, 8, 9, 10 mg, the pore size of the titanium-based solid phase filler can be 5, 6, 7, 8, 9, 10 nm, and the overall particle size can be 100, 125, 150, 175, 200 nm.

[0030] For example, the titanium-based solid phase filler has a pore size of 7 nm and a particle size of 150 nm.

[0031] The pore size and particle size of the titanium-based solid phase filler in the present invention can be controlled, which can ensure the recognition ability of small and medium-molecule DONs while taking into account the filtration efficiency.

[0032] Finally, the present invention also provides an application of the titanium-based syringe filter in detecting soluble organic nitrogen compounds in environmental samples.

[0033] Furthermore, the specific steps of detecting soluble organic nitrogen compounds in environmental samples include:

[0034] S1. Adjust the volume and concentration of the DOM sample after solid phase extraction pretreatment and refrigerate until ready for use;

[0035] S2. Activate the titanium syringe filter with methanol and connect it to the sample syringe for filtration and purification.

[0036] S3. The filtered and purified sample is directly injected into an ultra-high resolution mass spectrometry system for mass spectrometry detection and analysis.

[0037] Beneficial effects:

[0038] (1) The present invention uses titanium-based solid-phase fillers as functional fillers and fills them into a specially prepared titanium-based syringe filter for further selective treatment of DOM samples that have been pre-enriched by SPE. This design plays a role of secondary selective purification in the analytical process, which can effectively remove the background components of easily ionized carboxylic acids and phenolic oxygen-containing organic compounds, reduce mass spectrometry baseline noise, and significantly improve the detection sensitivity and quantitative reliability of soluble organic nitrogen compounds.

[0039] (2) The titanium-based solid phase filler provided by the present invention can selectively absorb carboxylic acid and phenolic oxygen-containing organic compounds accurately and efficiently. On the one hand, the TiO2 / MCM-41 molecular sieve filler can combine with the carboxylic acid functional group through a monodentate or bidentate coordination mode to form a stable Ti-OOC structure, thereby achieving highly selective adsorption of carboxyl functional group-containing compounds; on the other hand, by reacting amino-modified silane with TiO2 / MCM-41 molecular sieve, a large steric hindrance and amino group can be grafted on the molecular sieve, and phenolic oxygen anions can be electrostatically adsorbed after the amino group is protonated, and phenolic compounds can be selectively adsorbed through the benzene ring and the large steric hindrance structure.

[0040] (3) The titanium-based syringe filter containing titanium-based solid phase filler provided by the present invention has the advantages of small size, replaceability, strong adaptability, and suitability for rapid processing of small-volume samples compared with traditional column-type SPE materials. In addition, the titanium-based material filler proposed by the present invention has the characteristics of good thermal stability, high chemical tolerance, and strong selective adsorption, which overcomes the problem that traditional filters only have physical filtration functions and cannot achieve chemical selective adsorption. It is particularly suitable for the pre-analysis treatment needs of trace DONs in high-throughput environmental samples.

[0041] (4) The titanium-based syringe filter containing titanium-based solid-phase filler and its application method provided by the present invention have a small needle-type structure and are compatible with standard syringes and LC-MS interfaces, which are convenient for batch pretreatment and field detection. By combining with high-resolution mass spectrometry, it can achieve accurate quantification of trace DONs in complex DOM matrices. It is suitable for sample pretreatment in various water types and has broad potential for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the internal structure of the titanium-based syringe filter in Example 1 of the present invention.

[0043] Figure 2 This is a schematic diagram of the use of the titanium-based syringe filter of the present invention.

[0044] Figure 3This is a comparison of the high-resolution mass spectra of the dissolved organic nitrogen compounds (DONs) water sample before and after using a titanium-based syringe filter in the present invention.

[0045] Figure 4 This is a Venn diagram of the high-resolution mass spectrometry data for nitrogen-containing compounds before and after using a titanium-based syringe filter in the present invention.

[0046] Figure 5 This is a comparison of high-resolution mass spectra of a typical municipal sewage treatment plant influent sample before and after using a titanium-based syringe filter in the present invention.

[0047] Figure 6 For the present invention Figure 5 A partial enlarged view of . DETAILED DESCRIPTION

[0048] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0049] The platinum catalyst was 965005 purchased from Bailingwei Technology Co., Ltd. and diluted to a mass fraction of 4.0×10 -3 The remaining reagents and equipment are conventional reagents and equipment in this technical field.

[0050] Preparation of amino-modified silane

[0051] Amino-modified silane was prepared by the following steps:

[0052] In a reactor, 100 ml of isopropanol, 0.05 mol of diphenylchlorosilane and 0.06 mol of acrylamide were added, heated to 50° C., 0.1 ml of platinum catalyst was added, stirred for reaction for 4 hours, heated to 60° C., 20% dilute sulfuric acid was added, reacted for 3 hours, cooled, filtered, washed and dried to obtain the amino-modified silane.

[0053] Example 1

[0054] Titanium-based solid phase fillers were prepared by the following steps:

[0055] (1) First, add tetrabutyl titanate to isopropyl alcohol and stir evenly until it is completely dissolved; then add dodecyltrimethylammonium bromide and ethyl orthosilicate to the mixed solution respectively and continue stirring until it is completely dissolved; after adding ultrapure water, continue stirring for 30 minutes to ensure that the solution is uniform; use hydrochloric acid to adjust the pH value of the solution to 3.0 to ensure the stability of the sol and the hydrolysis process of TiO2; after the sol is prepared, continue stirring at room temperature for 2 hours until the solution forms a uniform sol system;

[0056] Among them, tetrabutyl titanate, dodecyltrimethylammonium bromide, ethyl orthosilicate, isopropyl alcohol and ultrapure water are in a molar ratio of 0.3:0.2:1.0:2.0:4.0;

[0057] (2) Sol aging: The prepared sol was placed in a stainless steel reactor lined with polytetrafluoroethylene. The reactor temperature was set at 100°C and the aging was continued for 12 hours. During the aging process, TiO2 began to grow in the MCM-41 pores and embedded into the silicon skeleton. During the aging process, TiO2 grew in situ within the MCM-41 pore structure to form a TiO2 / MCM-41 composite material.

[0058] (3) Filtration, drying and calcination: Filter the aged sol using a 500-mesh filter cloth to remove unreacted templates and impurities; rinse repeatedly with deionized water until the filtrate is colorless to ensure that all impurities and templates are removed; then, place the washed TiO2 / MCM-41 composite material in a drying oven at 100°C for 8 hours until the composite material is completely dry;

[0059] The dried TiO2 / MCM-41 composite material was transferred to a boat-shaped crucible and placed in a tube furnace for calcination at 500°C. The calcination time was 4 hours to ensure that the template was completely removed and the TiO2 was successfully loaded into the pores of the MCM-41. After calcination, the pore structure of the TiO2 / MCM-41 composite molecular sieve was stable, and the TiO2 was successfully loaded into the pores of the MCM-41, thus producing the TiO2 / MCM-41 molecular sieve.

[0060] (4) TiO2 / MCM-41 molecular sieve and amino-modified silane were added to the reactor, and the mixture was heated to 120°C after ultrasonic oscillation and reacted for 6 hours. After the reaction was complete, the mixture was cooled, filtered, washed, and dried to obtain the titanium-based solid phase filler.

[0061] like Figure 2 As shown, this embodiment provides a titanium-based syringe filter prepared based on a titanium-based solid phase filler. The filter has a compact structure, is resistant to high pressure and corrosion, and can be used for the selective enrichment and analysis of soluble organic nitrogen compounds (DONs).

[0062] (1) The titanium-based syringe filter mainly includes the following components: The left liquid inlet interface (liquid inlet cap): Made of polyetheretherketone (PEEK) material, it has excellent corrosion resistance and organic solvent resistance. The outside of the interface is equipped with fine anti-slip threads to facilitate the quick connection or removal of the injection line. The standard interface size is 1 / 16 inch;

[0063] Central body shell (fixed shell): Made of polypropylene, the filler part has a hexagonal prism appearance for easy clamping and positioning; the interior is a hollow structure for filling TiO2 / MCM-41 composite molecular sieve material; the surface is anodized or passivated to enhance corrosion resistance and weather resistance;

[0064] Right-side tightening knob (locking screw): Made of SUS304 stainless steel, with a rust-proof surface and a non-slip knurled pattern. This component simultaneously compresses the internal solid-phase packing and serves as a direct connection interface for the injection needle. A standard injection needle insertion port is provided internally, allowing direct insertion of a 0.5-0.8mm diameter injection needle. The threaded connection creates an airtight connection, facilitating rapid injection of samples into the filter.

[0065] (2) The filler is a titanium-based solid phase filler; the material with a pore size of about 7 nm and a particle size of about 150 nm is selected; it is filled in the hexagonal internal cavity of the central main body shell; the filling amount is controlled to 5 mg, and micro-vibration is used to assist in dense accumulation; the filling process is maintained uniformly to avoid obvious accumulation layers or channel deviation phenomena;

[0066] (3) A stainless steel microporous filter with a pore size of 10 μm is set at each end to support the solid phase filler and prevent it from leaking; the left liquid inlet cap and the right tightening knob are screwed together to form a stable and tight packaging structure.

[0067] Performance Testing

[0068] 1. The titanium-based syringe filter of the present invention is used to detect dissolved organic nitrogen compounds (DONs) in water samples. This method, which uses the titanium-based syringe filter to enrich DOM samples after solid-phase extraction (SPE), effectively removes interfering compounds, selectively enriches DONs, and improves detection sensitivity.

[0069] The specific steps include:

[0070] (1) Sample information: The samples used were surface water samples collected from Qingnian Lake (117.17°E, 39.11°N) on the Weijin Road campus of Tianjin University. The sampling point was 0.5 m below the lake surface and 2.0 m from the lake shore.

[0071] (2) Sample pretreatment: 200 mL of the above water sample was taken and filtered using a 0.45 μm filter membrane to remove large suspended solids. Subsequently, hydrochloric acid was added to adjust the pH value of the filtered water sample to 2. Next, DOM in the water sample was enriched using a PPL solid phase extraction column (500 mg, 6 mL). After enrichment, the enriched DOM sample was blown dry to 1 mL using nitrogen gas to facilitate subsequent testing.

[0072] (3) Use of titanium-based syringe filter: Take out the titanium-based syringe filter in Example 1 of the present invention, and use 5 mL of methanol to clean and activate it to remove residual impurities. The schematic diagram of its use is as follows Figure 2 One end of the filter is a syringe connector that supports direct insertion of the syringe; the other end is a PEEK tube connector that can be connected to the ionization source of a high-resolution mass spectrometer through the PEEK tube.

[0073] (4) Mass spectrometry acquisition: The water sample treated and concentrated by SPE was drawn into the injection needle, which was then connected in sequence to a titanium-based syringe filter, PEEK tubing, and the mass spectrometry ion source. The injection needle flow rate was set to 0.30 mL / h. High-resolution mass spectrometry analysis was performed using the electrospray ionization (ESI) source of the FT-ICR MS in positive ion mode (+). The mass resolution of the FT-ICR MS was 450,000 at m / z 400. Broadband 4M acquisition was used, with a mass acquisition range of m / z 150-1000 and 256 spectral overlays.

[0074] At the same time, under the same experimental conditions, mass spectrometry data of a sample without a titanium-based syringe filter were collected for comparative analysis.

[0075] The specific operation was to draw the SPE-treated and concentrated water sample directly into the injection needle, which was then connected directly to the mass spectrometer ion source via PEEK tubing. Parameters such as injection needle flow rate, mass spectrometry analysis mode, mass resolution, acquisition range, and number of spectral overlays remained consistent with the previous steps to ensure comparability of the comparison data.

[0076] (5) Data analysis: After the sample test is completed, the data is recalibrated using an internal reference mass table. After internal calibration, the mass error is ensured to be no more than 600 ppb over the entire mass range. Mass spectral peaks with a signal-to-noise ratio greater than 6 are selected, and the compounds are assigned an accurate chemical formula based on the specific number of carbon, hydrogen, oxygen, nitrogen, and sulfur atoms. A detailed list of molecular masses and chemical formulas is generated. The number of carbon atoms ranges from 1 to 80, the number of hydrogen atoms ranges from 2 to 120, the number of oxygen atoms ranges from 0 to 25, the number of nitrogen atoms ranges from 0 to 3, and the number of sulfur atoms ranges from 0 to 2.

[0077] (6) Experimental results and analysis: The experimental results are as follows Figure 3 and Figure 4 shown.

[0078] Figure 3Comparison of high-resolution mass spectra of dissolved organic nitrogen compounds (DONs) in a water sample before and after treatment with a titanium-based syringe filter. The results show that treatment with the titanium-based syringe filter effectively removed carboxylic acids such as CHO and CHOS, phenolic oxygenated organic compounds, and sodium-containing compounds from the original DOM sample, demonstrating the filter's significant removal of these compounds. Removal of these interfering compounds significantly enhanced the detection signals of CHN, CHNO, and CHNOS compounds. Figure 4 This diagram shows a Venn diagram of high-resolution mass spectrometry data for nitrogen-containing compounds before and after using a titanium-based syringe filter. The figure shows that using the titanium-based syringe filter resulted in the detection of 3,732 additional nitrogen-containing compounds, representing 43.24% of the total. Only 47.61% of the nitrogen-containing compounds were undetectable due to adsorption by the filter due to their inherent carboxyl groups.

[0079] 2. The titanium-based syringe filter system provided by the present invention was used to enrich and analyze DONs in influent samples from typical municipal sewage treatment plants.

[0080] The specific steps include:

[0081] (1) Sample information: Untreated raw water samples were collected at the water inlet of a large sewage treatment plant.

[0082] (2) Sample pretreatment: 50 mL of the above water sample was taken and filtered using a 0.45 μm filter membrane to remove large suspended solids. Subsequently, hydrochloric acid was added to adjust the pH value of the filtered water sample to 2. Next, DOM in the water sample was enriched using a PPL solid phase extraction column (200 mg, 3 mL). After enrichment, the enriched DOM sample was blown dry to 1 mL using nitrogen gas to facilitate subsequent testing.

[0083] (3) Use of titanium-based syringe filter: Take out the titanium-based syringe filter of Example 1 of the present invention, and use 5 mL of methanol to clean and activate it to remove residual impurities. The schematic diagram of its use is as follows Figure 2 One end of the filter is a syringe connector that supports direct insertion of the syringe; the other end is a PEEK tube connector that can be connected to the ionization source of a high-resolution mass spectrometer through the PEEK tube.

[0084] (4) Mass spectrometry acquisition: The water sample treated and concentrated by SPE was drawn into the injection needle, which was then connected in sequence to a titanium-based syringe filter, PEEK tubing, and the mass spectrometry ion source. The injection needle flow rate was set to 0.30 mL / h. High-resolution mass spectrometry analysis was performed using the electrospray ionization (ESI) source of the FT-ICR MS in positive ion mode (+). The mass resolution of the FT-ICR MS was 450,000 at m / z 400. Broadband 4M acquisition was used, with a mass acquisition range of m / z 150-1000 and 256 spectral overlays.

[0085] In parallel, mass spectrometry data were collected under identical experimental conditions without the titanium-based syringe filter attached for comparative analysis. Specifically, the SPE-treated and concentrated water sample was drawn directly into the syringe, which was then connected directly to the mass spectrometer ion source via PEEK tubing. Parameters such as syringe flow rate, mass spectrometry analysis mode, mass resolution, acquisition range, and number of spectral overlays remained consistent with those in the previous steps to ensure comparability of the comparative data.

[0086] (5) Data analysis: After the sample test is completed, the data is recalibrated using an internal reference mass table. After internal calibration, the mass error is ensured to be no more than 600 ppb over the entire mass range. Mass spectral peaks with a signal-to-noise ratio greater than 6 are selected, and the compounds are assigned an accurate chemical formula based on the specific number of carbon, hydrogen, oxygen, nitrogen, and sulfur atoms. A detailed list of molecular masses and chemical formulas is generated. The number of carbon atoms ranges from 1 to 80, the number of hydrogen atoms ranges from 2 to 120, the number of oxygen atoms ranges from 0 to 25, the number of nitrogen atoms ranges from 0 to 3, and the number of sulfur atoms ranges from 0 to 2.

[0087] (6) Experimental results and analysis: The experimental results are as follows Figure 5 shown.

[0088] Figure 5 Comparison of high-resolution mass spectra of a typical municipal wastewater treatment plant influent sample before and after treatment with a titanium-based syringe filter. The results show that the raw wastewater DOM sample contains typical surfactants, whose strong polarity produces a series of intense peaks across the entire mass detection range, significantly obscuring the mass spectrometric signals of DOM compounds. Treatment with the titanium-based syringe filter significantly removes these surfactants. For example, in the zoomed-in view of the mass spectrum at m / z 371, the peak for nitrogen-containing compounds can be clearly observed, demonstrating that the filter effectively reduces interference and improves the sensitivity of nitrogen-containing compound detection.

[0089] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A titanium-based solid phase filler, characterized in that: Prepared by the following steps: (1) In a reactor, tetrabutyl titanate is mixed with dodecyltrimethylammonium bromide, ethyl orthosilicate, isopropyl alcohol, and ultrapure water. After sufficient stirring, a uniform sol is formed, and the pH value is adjusted with hydrochloric acid. (2) The prepared sol is aged at a certain temperature. During the aging process, TiO2 grows in situ within the pore structure of MCM-41 to form a TiO2 / MCM-41 composite material; (3) After aging, the unreacted template and impurities are removed by filtration and washing, and the template is removed after drying and calcination to obtain TiO2 / MCM-41 molecular sieve; (4) adding TiO2 / MCM-41 molecular sieve and amino-modified silane into a reactor, heating and reacting after ultrasonic vibration, cooling, filtering, washing, and drying after the reaction is complete to obtain the titanium-based solid phase filler; In step (2), the aging temperature is 100-150° C. and the aging time is 12-48 h; In step (4), the heating temperature is 110-130°C and the reaction time is 4-6h; The amino-modified silane has a structure shown in the following formula A: 。 2. The titanium-based solid-phase filler according to claim 1, characterized in that: In the step (1), the molar ratio of tetrabutyl titanate, dodecyltrimethylammonium bromide, ethyl orthosilicate, isopropyl alcohol and ultrapure water is (0.1-0.5) : (0.1-0.3) : (0.5-2) : (1-3) : (2-5), and the pH of the sol is 2-4.

3. The titanium-based solid-phase filler according to claim 1, characterized in that: In step (3), the drying temperature is 80-120°C, and the drying time is 6-12 h; the calcination temperature is 350-800°C, and the calcination time is 3-8 h.

4. The titanium-based solid-phase filler according to claim 1, characterized in that: The amino-modified silane is prepared by the following steps: adding a solvent, diphenylchlorosilane and acrylamide into a reactor, heating to 40-50° C., adding a platinum catalyst, stirring for reaction for 3-4 hours, then heating to 55-60° C., adding dilute sulfuric acid for reaction for 2-3 hours, cooling, filtering, washing and drying to obtain the amino-modified silane.

5. The titanium-based solid-phase filler according to claim 4, characterized in that: The effective platinum content in the platinum catalyst is 1.0×10 of the total mass of the reactants. -5 -5.0×l0 -5 The mass concentration of the dilute sulfuric acid is 15-25%; the molar ratio of diphenylchlorosilane to acrylamide is 1:1.2-1.

5.

6. A titanium-based syringe filter, characterized in that: The titanium-based syringe filter comprises the titanium-based solid phase filler according to any one of claims 1 to 5; The titanium-based syringe filter comprises a left-side liquid inlet port, a central main body shell, and a right-side tightening knob; The titanium-based solid phase filler is filled in the central main body shell, and the filling amount is controlled to be 3-10 mg; The titanium-based solid-phase filler has a pore size of 5-10 nm and an overall particle size of 100-200 nm.

7. Use of the titanium-based syringe filter according to claim 6 in detecting dissolved organic nitrogen compounds in environmental samples.

8. The use according to claim 7, characterized in that The specific steps of detecting soluble organic nitrogen compounds in environmental samples include: S1. Adjust the volume and concentration of the DOM sample after solid phase extraction pretreatment and refrigerate until ready for use; S2. Activate the titanium syringe filter with methanol and connect it to the sample syringe for filtration and purification. S3. The filtered and purified sample is directly injected into an ultra-high resolution mass spectrometry system for mass spectrometry detection and analysis.

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