A method for screening of high-yield active oxygen natural suspended particulate matter and degradation of new pollutants

Abstract

The application discloses a method for screening high-yield active oxygen natural suspended particles and degrading new pollutants, and steps of the method comprise the following steps: firstly, collecting suspended particles from surface water, determining chemical oxygen demand COD and surface organic matter aromaticity of the suspended particles, and screening the suspended particles with high-yield active oxygen activity; adding the high-yield active suspended particles to water bodies containing new pollutants to be treated, so that the suspended particles adsorb the new pollutants to surfaces of the suspended particles, and providing light after the adsorption is completed to make the suspended particles generate high-concentration active oxygen on the surfaces, so that rapid degradation of the new pollutants is realized. The application has the characteristics of green, economic, high efficiency and easy operation in removing the new pollutants.

Description

Technical Field

[0001] This invention belongs to the field of water treatment, specifically relating to a method for screening high-yield active oxygen-producing natural suspended particulate matter and its degradation of new pollutants. Background Technology

[0002] With the increasing production and use of various chemicals by humans, a large number of new pollutants have entered natural water bodies and have been detected in many water bodies around the world. These new pollutants often exhibit characteristics such as biotoxicity, environmental persistence, and bioaccumulation. These new pollutants entering water bodies can threaten ecological security and human health through various pathways, including ingestion, inhalation, and skin contact by humans and animals.

[0003] Wastewater treatment plants are the last line of defense in urban and rural water systems. However, the mainstream activated sludge process used in wastewater treatment plants is ineffective at removing new pollutants that are difficult to biodegrade. To remove residual new pollutants in the effluent, advanced treatment methods, such as advanced oxidation technologies (AEOs), are often required. AEOs can efficiently degrade new pollutants by generating highly reactive oxygen species with strong oxidizing properties, such as photocatalytic oxidation, ozone oxidation, electrochemical oxidation, and Fenton oxidation. However, current AEOs suffer from various problems in practical applications, including high treatment costs, high energy consumption, high oxidant consumption, and secondary pollution. Therefore, there is an urgent need to develop an economical, green, simple, and efficient treatment method to address the problem of residual new pollutants in wastewater treatment plant effluent. Summary of the Invention

[0004] This invention addresses the problems existing in the treatment of new pollutants in existing wastewater treatment plants by providing a method for screening and degrading new pollutants using naturally suspended particulate matter with high active oxygen production. The aim is to utilize the characteristics of suspended particulate matter—being green and non-toxic, low-cost, easily adsorbing new pollutants, and generating high concentrations of active oxygen on its surface under light—to achieve efficient and low-cost degradation of new pollutants in wastewater.

[0005] To achieve its objectives, the present invention employs the following technical solution:

[0006] A method for screening high-yield reactive oxygen species in naturally suspended particulate matter and degrading novel pollutants includes the following steps:

[0007] (1) Screening of highly active suspended particulate matter: Suspended particulate matter was collected from surface water, and the chemical oxygen demand (COD) and surface organic matter aroma of the suspended particulate matter were determined. Suspended particulate matter with high COD and high surface organic matter aroma was screened as highly active suspended particulate matter.

[0008] (2) Suspended particulate matter adsorbs new pollutants: The highly active suspended particulate matter obtained in step (1) is added to the water body containing new pollutants at a final concentration of 0.1 to 1 g / L and stirred in the dark for 0.5 to 4 hours to allow the suspended particulate matter to adsorb the new pollutants onto its surface.

[0009] (3) Photodegradation of new pollutants: After the suspended particulate matter has reached equilibrium with the adsorption of new pollutants, light is provided to stimulate the suspended particulate matter to generate active oxygen to degrade the new pollutants; the concentration change of the new pollutants is monitored until the wastewater meets the treatment requirements.

[0010] Further, in step (1), the process for collecting suspended particulate matter is as follows: First, surface water is passed through a 200-mesh sieve, and the filtrate is collected. Then, the filtrate is passed through a 0.45 μm cellulose acetate membrane. During this process, the membrane is replaced when the filtration speed is too slow, and the filtered membrane is collected. All the filtered membranes are added to an appropriate amount of deionized water and sonicated for 10 minutes to remove the suspended particulate matter from the membrane, resulting in a concentrated suspended particulate matter solution. The concentrated suspended particulate matter solution is dispensed into 50 mL centrifuge tubes and centrifuged at 6000 rpm for 5 minutes. The supernatant is discarded, and the suspended particulate matter is resuspended in deionized water and vortexed to disperse it evenly. The mixture is then centrifuged again at 6000 rpm for 5 minutes. This process is repeated three times to complete the washing. The washed suspended particulate matter is then freeze-dried in a freeze dryer at -50℃ for 24–48 hours to obtain the dried suspended particulate matter, which is stored at room temperature in the dark for later use.

[0011] Further, in step (1), the determination of COD of suspended particulate matter is as follows: the dried suspended particulate matter is resuspended in deionized water, and ultrasonically dispersed to achieve full dispersion. The concentration of suspended particulate matter is 0.1-1 g / L. The COD of the dispersed suspension is then determined. The specific method for COD determination refers to "Methods for Monitoring and Analysis of Water and Wastewater, Fourth Edition" (China Environmental Publishing House, Beijing). After the COD of the suspension (unit mg / L) is determined according to this method, it is normalized according to the concentration of suspended particulate matter and converted to g / g, that is, the COD per gram of suspended particulate matter.

[0012] Further, in step (1), the determination of the aromaticity of the organic matter on the surface of the suspended particulate matter is as follows: The dried suspended particulate matter is added to a 0.1M NaOH solution, the concentration of the suspended particulate matter is 0.1–1 g / L, and shaken for 24 h at room temperature and in the dark to extract the organic matter on the surface of the particulate matter. Then, it is neutralized to pH = 7 with 6M HCl, and then passed through a 0.45 μm cellulose acetate membrane. The filtrate is collected to obtain the extracted organic matter solution. The ultraviolet-visible absorption spectrum of the extracted organic matter solution is measured, and the ratio of the absorbance at 254 nm to 204 nm (AL) is calculated. 254 / A 204As an indicator of the aromaticity of organic matter, this ratio is positively correlated with aromaticity.

[0013] Furthermore, the COD of the highly active suspended particulate matter is >0.5 g / g, and A 254 / A 204 >0.27.

[0014] Furthermore, the method of the present invention is applicable to the treatment of a variety of novel pollutants, including but not limited to one or more of cimetidine and metopidine.

[0015] Furthermore, in actual water treatment, the illumination treatment in step (3) directly uses sunlight. In the experiment of this invention, a 500W xenon lamp was used as the light source, and a 290nm filter was used to filter light with wavelengths below 290nm to simulate sunlight.

[0016] Furthermore, in step (3), the monitoring of the changes in the concentration of the new pollutant is performed by high performance liquid chromatography equipped with an ultraviolet detector. The determination method is as follows: 5mM KH2PO4 (pH=3) and acetonitrile are used as the mobile phase, and the detection wavelength is 219nm.

[0017] The beneficial effects of this invention are reflected in:

[0018] 1. This invention utilizes natural suspended particulate matter to degrade new pollutants. Suspended particulate matter is inexpensive, readily available, and non-toxic, and will not cause secondary pollution.

[0019] 2. The method for screening highly active suspended particulate matter proposed in this invention is simple to operate. The screened suspended particulate matter can generate a high concentration of active oxygen on the surface under light, which degrades new pollutants adsorbed on the surface. No special devices or equipment are required, the operation is simple, and it is easy to promote.

[0020] 3. The suspended particulate matter screened by this invention can utilize sunlight when treating pollutants, without the need for additional energy input. Attached Figure Description

[0021] Figure 1 Qualitative and quantitative characterization of reactive oxygen species (ROS) generated by suspended particulate matter (SPM) in Example 1: (a) Imaging results of reactive oxygen species fluorescent probes; (b) Degradation kinetics of singlet oxygen probe (furfuryl alcohol).

[0022] Figure 2 The degradation kinetics curve of cimetidine in Example 2 is shown.

[0023] Figure 3The comparison of singlet oxygen generation and cimetidine degradation by different SPMs in Example 3 is as follows: (a) COD and aromaticity of different SPMs; (b) kinetic curves of singlet oxygen probe (furfuryl alcohol) degradation by different SPMs; (c) steady-state concentration of singlet oxygen generated by different SPMs; (d) kinetic curves of cimetidine degradation by different SPMs.

[0024] Figure 4 The degradation kinetics curve of metoprimidine in Example 4 is shown. Detailed Implementation

[0025] To more clearly describe the technical solution of the present invention, preferred embodiments are described in detail below with reference to the accompanying drawings. Obviously, the technical solution of the present invention is not limited to the specific embodiments listed below. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In all the embodiments described below, the light source used is a 500W xenon lamp, and it is equipped with a 290nm filter to filter light with wavelengths below 290nm in order to simulate sunlight.

[0027] Example 1

[0028] 1. Collection of suspended particulate matter (SPM)

[0029] First, 50 L of surface water containing SPM was passed through a 200-mesh sieve, and the filtrate was collected. Then, the filtrate was passed through a 0.45 μm cellulose acetate membrane, replacing the membrane when the filtration rate became too slow, and the filtered membrane was collected. All the filtered membranes were placed in a 500 mL plastic beaker, and 200 mL of deionized water was added. The mixture was sonicated for 10 min to detach the SPM from the membrane, and the membrane was discarded to obtain a concentrated SPM solution. The concentrated SPM solution was dispensed into 50 mL centrifuge tubes and centrifuged at 6000 rpm for 5 min. The supernatant was discarded, and the SPM was resuspended in deionized water and vortexed to disperse it evenly. The mixture was then centrifuged again at 6000 rpm for 5 min, and this process was repeated three times to complete the washing. The washed SPM was then freeze-dried at -50°C for 24 h to obtain dried SPM, which was stored at room temperature in the dark for later use.

[0030] In step 1, the surface water was taken from the China Railway Construction International City Wetland Park in Hefei, Anhui Province in April 2024, and the suspended particulate matter obtained was SPM-4.

[0031] 2. Qualitative evidence of SPM generating reactive oxygen species (ROS)

[0032] Weigh 4 mg of the SPM obtained in step 1 into a 2 mL plastic centrifuge tube, add 0.4 mL of deionized water, and sonicate for 10 min to achieve thorough dispersion, obtaining an SPM suspension. Prepare a ROS-capturing gel membrane. Place the ROS-capturing gel membrane horizontally, add an appropriate amount of deionized water to wet its surface, and carefully add 50 μL of the above SPM suspension to the center of the ROS-capturing gel membrane. Let it stand for 3 min to allow the SPM to precipitate onto its surface. Irradiate the membrane vertically for 1 min using a 10 W UV LED lamp with a wavelength range of 360–365 nm. Take bright-field and fluorescence images of the ROS-capturing gel membrane using a stereofluorescence microscope. The excitation wavelength for the fluorescence image is 488 nm, and the emission wavelength is 525 nm. ROS oxidizes the probe 2',7'-dichlorodihydrofluorescein (H2DCF) to generate a green fluorescent product, 2',7'-dichlorofluorescein (DCF). Green fluorescence can be observed in suspended particles after illumination (see [link to product description]). Figure 1 (a) indicates that ROS was generated on its surface.

[0033] The steps for preparing the ROS capture gel membrane are as follows: First, weigh 3.9 mg of 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA, a fluorescent ROS probe) into a 2 mL plastic centrifuge tube, add 400 μL of N,N-dimethylformamide (DMF) solvent, dissolve thoroughly, then add 400 μL of 20 mM NaOH solution, and incubate at 37°C in the dark for 30 min to hydrolyze it into 2',7'-dichlorodihydrofluorescein (H2DCF). Then, add 1.2 g of agarose to a 100 mL Erlenmeyer flask containing 60 mL of phosphate-buffered saline (PBS) (10 mM, pH = 7), heat in a microwave oven for 3 min to fully dissolve the agarose, and after cooling to about 60°C, add 600 μL of the above H2DCF solution, shake well, and fill the agarose gel mixture into a 2 × 2 cm plastic binding plate. The ROS-capturing gel membrane was obtained by curing at 4°C in the dark for 2 hours.

[0034] 3. Quantitative proof of ROS generation by SPM

[0035] The SPM obtained in step 1 was added to 4 mL of a solution containing 50 μM singlet oxygen probe (furfuryl alcohol), mixed thoroughly, and the pH was adjusted to 8. The final concentration of SPM was 0.4 g / L. A 10 mL quartz tube was used, and the solution was placed in a photoreactor and stirred in the dark for 2 hours to reach adsorption equilibrium, after which light was provided. The reaction temperature was controlled at 25 ± 1 °C using circulating water, and the stirring speed was controlled at 800 rpm using magnetic stirring. The concentration change of furfuryl alcohol in the water was detected by high-performance liquid chromatography (see [link to article]). Figure 1(b) The detection method was as follows: water and acetonitrile were used as the mobile phase, and the detection wavelength was 219 nm. Based on the pseudo-first-order degradation rate of furfuryl alcohol, the steady-state concentration of singlet oxygen generated by SPM was found to be 1.66 × 10⁻⁶. -13 M. The specific quantitative method for the steady-state concentration of reactive oxygen species is described in the literature "The Role of Dissolved Organic Matter Composition in Determining Photochemical Reactivity at the Molecular Level".

[0036] Example 2

[0037] 1. Same as step 1 in Example 1.

[0038] 2. Photodegradation of new pollutants:

[0039] The SPM obtained in step 1 was added to 4 mL of water containing 2 mg / L cimetidine, resulting in a final SPM concentration of 0.4 g / L. A 10 mL quartz tube was used, and the tube was placed in a photoreactor and stirred in the dark for 2 hours to reach adsorption equilibrium. Then, light was applied to excite the SPM to generate reactive oxygen species for cimetidine degradation. The reaction temperature was controlled at 25 ± 1 °C using circulating water, and the stirring speed was controlled at 800 rpm using magnetic stirring. The residual cimetidine concentration was detected by high-performance liquid chromatography (HPLC) using 5 mL M KH₂PO₄ (pH = 3) and acetonitrile as the mobile phase, with a detection wavelength of 219 nm.

[0040] After 6 hours of light exposure, cimetidine in water with added SPM was degraded by 73.0%, while cimetidine in water without added SPM was not degraded (see [link to article]). Figure 2 This indicates that SPM generates reactive oxygen species under light, which can cause the degradation of cimetidine.

[0041] Example 3

[0042] 1. Similar to step 1 of Example 1, except that different SPMs were collected from different surface water bodies. The sampling locations and times for different SPMs are shown in Table 1.

[0043] Table 1. Sampling locations and times for different suspended particulate matter (SPM)

[0044] Suspended particulate matter Longitude (E) of the sampling location Latitude (N) of the sampling location Sampling time SPM-1 117.236 31.878 2024.04 SPM-2 117.238 31.876 2024.04 SPM-3 117.250 31.841 2024.04 SPM-4 117.240 31.901 2024.04

[0045] 2. SPM screening with different ROS production activities

[0046] The COD and surface organic matter aromaticity of different SPMs obtained in step 1 were determined, and SPMs with different ROS-producing activities were screened (see [link to article]). Figure 3(a)), where the ROS production activity of SPM is positively correlated with its COD and the aromaticity of surface organic matter. The order of ROS production activity of SPM is: SPM-1 < SPM-2 < SPM-3 < SPM-4. Among them:

[0047] The steps for measuring the COD of SPM are as follows: Weigh 4 mg of the SPM obtained in step 1 and place it in a 50 mL plastic centrifuge tube. Add 10 mL of deionized water and ultrasonicate for 10 min to achieve sufficient dispersion. Then measure the COD of the dispersed suspension. The specific method for COD measurement refers to the "Fourth Edition of Monitoring and Analysis Methods for Water and Wastewater" (China Environmental Science Press, Beijing). After measuring the COD (unit: mg / L) of the SPM suspension by this method, normalize it according to the concentration of SPM and convert it to g / g, that is, the COD per g of SPM.

[0048] The steps for measuring the aromaticity of surface organic matter of SPM are as follows: Weigh 4 mg of the SPM obtained in step 1 and place it in a 50 mL plastic centrifuge tube. Add 10 mL of 0.1 M NaOH solution and shake it at room temperature in the dark for 24 h to extract the organic matter on the surface of the particles. Then neutralize it to pH = 7 with 6 M HCl, and then pass it through a 0.45 μm cellulose acetate membrane. Collect the filtrate to obtain the extracted organic matter solution. Measure the ultraviolet-visible absorption spectrum of the extracted organic matter solution, and use the ratio of absorbance at 254 nm and 204 nm (A 254 / A 204 ) as an index to judge the aromaticity of organic matter. This ratio is positively correlated with the aromaticity.

[0049] 3. Steady-state concentration of singlet oxygen generated by different SPMs

[0050] Add the different SPMs obtained in step 1 above to 4 mL of a solution containing 50 μM singlet oxygen probe (furfuryl alcohol) respectively. The final concentration of SPM is 0.4 g / L. The container used is a 10 mL quartz test tube. Place it in a photoreactor and stir it in the dark for 2 h to reach the adsorption equilibrium, and then provide light. Control the reaction temperature at 25 ± 1 °C through circulating water, control the stirring speed at 800 rpm through magnetic stirring, and detect the change in the concentration of furfuryl alcohol in water by high performance liquid chromatography (see Figure 3 (b)). According to the pseudo-first-order degradation rate of furfuryl alcohol, the order of the steady-state concentration of singlet oxygen generated by different SPMs can be obtained: SPM-1 < SPM-2 < SPM-3 < SPM-4 (see Figure 3(c)), which is consistent with the results screened in step 2, proving the reliability of the screening method in step 2. The specific quantitative method for the steady-state concentration of reactive oxygen species refers to the literature "The Role of Dissolved Organic Matter Composition in Determining Photochemical Reactivity at the Molecular Level".

[0051] 4. Efficiency of Different SPMs in Degrading New Pollutants

[0052] The different SPMs obtained in step 1 were respectively added to 4 mL of the water to be treated containing 2 mg / L cimetidine. The final concentration of SPM was 0.4 g / L. The container used was a 10 mL quartz test tube, which was placed in a photoreactor and stirred in the dark for 2 h to reach the adsorption equilibrium. Then, light was provided to stimulate the SPM to generate reactive oxygen species for the degradation of cimetidine. The reaction temperature was controlled at 25 ± 1 °C by circulating water, the stirring speed was controlled at 800 rpm by magnetic stirring, and the residual cimetidine concentration was detected by high-performance liquid chromatography. The detection method was: 5 mM KH2PO4 (pH = 3) and acetonitrile as the mobile phase, and the detection wavelength was 219 nm.

[0053] After 6 h of light irradiation, the efficiency order of SPM in degrading cimetidine was: SPM-1 < SPM-2 < SPM-3 < SPM-4 (see Figure 3 (d)), which is consistent with the results screened in step 2, further proving the reliability of the screening method in step 2. By screening, SPMs with high reactive oxygen production can be obtained to achieve more efficient degradation of new pollutants.

[0054] Example 4

[0055] 1. The same as step 1 of Example 1.

[0056] 2. Photodegradation of New Pollutants

[0057] The SPM obtained in step 1 was added to 4 mL of the water to be treated containing 2 mg / L medetomidine. The final concentration of SPM was 0.4 g / L. The container used was a 10 mL quartz test tube, which was placed in a photoreactor and stirred in the dark for 2 h to reach the adsorption equilibrium. Then, light was provided to stimulate the SPM to generate reactive oxygen species for the degradation of medetomidine. The reaction temperature was controlled at 25 ± 1 °C by circulating water, the stirring speed was controlled at 800 rpm by magnetic stirring, and the residual medetomidine concentration was detected by high-performance liquid chromatography. The detection method was: 5 mM KH2PO4 (pH = 3) and acetonitrile as the mobile phase, and the detection wavelength was 219 nm.

[0058] After 6 hours of light exposure, 94.7% of medoxomidine was degraded in water in which SPM was added (see...). Figure 4 ),contrast Figure 2 This indicates that SPM exhibits good degradation effects on different types of new pollutants.

[0059] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for screening high-yield reactive oxygen species in naturally suspended particulate matter and degrading new pollutants, characterized in that, Includes the following steps: (1) Screening of highly active suspended particulate matter: Suspended particulate matter was collected from surface water, and the chemical oxygen demand (COD) and surface organic matter aromaticity of the suspended particulate matter were determined. Suspended particulate matter with high COD and high surface organic matter aromaticity was screened as highly active suspended particulate matter. The highly active suspended particulate matter had a COD > 0.5 g / g and A 254 / A 204 >0.27; The procedure for determining the aromaticity of organic matter on the surface of suspended particulate matter is as follows: The dried suspended particulate matter is added to a 0.1M NaOH solution, with a concentration of 0.1–1 g / L. The solution is shaken for 24 h at room temperature and in the dark to extract the organic matter from the surface of the particulate matter. The solution is then neutralized to pH 7 with 6 M HCl, passed through a 0.45 μm cellulose acetate membrane, and the filtrate is collected to obtain the extracted organic matter solution. The UV-Vis absorption spectrum of the extracted organic matter solution is measured, and the ratio A of the absorbance at 254 nm and 204 nm is calculated. 254 / A 204 As an indicator of the aromaticity of organic matter, this ratio is positively correlated with aromaticity; (2) Suspended particulate matter adsorbs new pollutants: The highly active suspended particulate matter obtained in step (1) is added to the water body to be treated containing new pollutants and stirred in the dark so that the suspended particulate matter adsorbs the new pollutants onto its surface. (3) Photodegradation of new pollutants: After the suspended particulate matter adsorbs new pollutants and reaches equilibrium, light is provided to excite the surface of the suspended particulate matter to generate active oxygen to degrade the new pollutants. The active oxygen is singlet oxygen. The concentration change of the new pollutants is monitored until the wastewater meets the treatment requirements.

2. The method according to claim 1, characterized in that: In step (1), the steps for collecting suspended particulate matter are as follows: first, pass the surface water through a 200-mesh sieve and collect the filtrate; then, pass the filtrate through a 0.45 μm cellulose acetate membrane and collect the suspended particulate matter on the cellulose acetate membrane. After washing with deionized water, place it at -50 ℃ for vacuum freeze-drying for 24 to 48 h to obtain the dried suspended particulate matter, and store it at room temperature in the dark for later use.

3. The method according to claim 1, characterized in that: In step (1), the COD determination of the suspended particulate matter is as follows: the dried suspended particulate matter is resuspended in deionized water, and ultrasonically dispersed to achieve full dispersion, and the COD of the dispersed suspension is determined.

4. The method according to claim 1, characterized in that: In step (2), the highly active suspended particulate matter is added to the water body containing the new pollutants at a final concentration of 0.1 to 1 g / L.

5. The method according to claim 1, characterized in that: In step (2), the stirring time is 0.5 to 4 hours.

6. The method according to claim 1, characterized in that: In step (3), the light source is a xenon lamp simulating sunlight or real sunlight.

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