Method for removing acetaminophen in water based on visible light excited humic acid activated PMS

Abstract

The invention provides a method for removing acetaminophen (APAP) in water based on visible light excited humic acid activated peroxymonosulfate (PMS), the method is used for removing acetaminophen in water by utilizing oxidizing substances such as singlet oxygen generated by the humic acid activated PMS, and the humic acid in the system has photosensitive activity under visible light, so that the pH value of the system is improved, and the service life of the system is prolonged. The photoexcited humic acid can activate PMS to decompose and generate a large number of reactive oxygen species, accelerate degradation of APAP, and also can remove APAP through self photosensitization. Reaction active substances generated by activating PMS by humic acid are mainly singlet oxygen, and further comprise superoxide anions, hydroxyl radicals and the like. According to the method, the organic pollutant APAP is degraded by utilizing the visible light to excite the humic acid to activate the PMS, so that the efficiency of a PMS oxidizing agent is greatly improved, and the method has very high practical applicability. The PMS activating reagent is a common organic matter component humic acid in an environmental water body and has good environmental safety, and use of a traditional transition metal-based PMS activating agent is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of advanced oxidation for environmental water treatment, in particular to a method for removing acetaminophen in water based on visible light-excited humic acid and activated PMS. Background Art

[0002] With the rapid development of industrialization and urbanization, the concentration of pharmaceutical pollutants in the water environment has increased significantly, becoming one of the major issues of global environmental pollution. Acetaminophen (APAP), a widely used over-the-counter antipyretic and analgesic, has become increasingly serious in medical wastewater, industrial wastewater and domestic sewage. APAP has good water solubility and stability, which makes it difficult to effectively remove it by traditional physical adsorption, chemical oxidation and biodegradation methods. As a result, it exists in water bodies for a long time, posing a potential threat to aquatic organisms and human health. Studies have shown that APAP in water bodies may not only cause endocrine disorders and liver and kidney damage, but may also further aggravate environmental risks through its degradation products.

[0003] Currently, the methods for removing APAP from water mainly include:

[0004] Physical adsorption: such as using materials such as activated carbon and zeolite. Although the adsorption process is simple, the regeneration and treatment of the adsorbent increases the cost, and it cannot achieve complete degradation, posing a risk of secondary pollution.

[0005] Chemical oxidation: including ozone oxidation, chlorination oxidation and advanced oxidation processes (AOPs). Chemical oxidation reactions often have harsh conditions and high energy consumption. Some methods may produce toxic byproducts, affecting environmental safety.

[0006] Biodegradation: Using microorganisms to degrade APAP. However, APAP is toxic to microorganisms at high concentrations, and the degradation process is slow, so the effect is limited.

[0007] In view of the limitations of the above methods, the development of efficient, green and sustainable APAP removal technology has become an urgent issue to be solved. Advanced oxidation processes (AOPs) have attracted much attention because of their ability to produce highly active oxygen free radicals, and have the advantages of strong oxidation ability, fast reaction speed and good broad spectrum. Common AOPs include Fenton reaction, photocatalytic oxidation, electrochemical oxidation and ozone oxidation.

[0008] In recent years, persulfate, as a new type of oxidant, has shown excellent performance in AOPs. Persulfate includes peroxymonosulfate (PMS) and peroxydisulfate. Persulfate has the advantages of low toxicity, low price, easy operation and single-electron oxidation. Advanced oxidation technology based on persulfate plays an important role in the treatment of environmental pollution. However, the methods used in the prior art to activate PMS to degrade pollutants generally have the following disadvantages: ① Excessive energy / chemical input is required; ② Metal-loaded catalysts may cause secondary pollution to the environment and are not suitable for practical applications; ③ Ultraviolet light accounts for less than visible light in the solar spectrum, which limits the practical application of the UV-activated PMS strategy.

[0009] Humic acid (HA), as an organic matter naturally existing in the water environment, has abundant functional groups (such as carboxyl and phenolic hydroxyl groups), can react with a variety of metal ions and organic matter to form complexes, and exhibits good performance in adsorbing heavy metal ions and photosensitizing organic matter. The development of humic acid as a photosensitizer can effectively activate PMS, generate highly active oxygen free radicals, and achieve efficient degradation of organic pollutants. The environmentally friendly advantages of humic acid can be used to avoid the secondary pollution problems that may be introduced by traditional transition metal catalysts, which meets the requirements of green environmental protection.

[0010] Therefore, it is of great application prospect to develop a new AOPs system based on visible light-excited humic acid to activate PMS, optimize the reaction conditions, and improve the removal efficiency of APAP while maintaining the green and environmental protection characteristics and economic feasibility of the system. Summary of the invention

[0011] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for removing acetaminophen in water based on visible light-excited humic acid-activated PMS, so as to solve the problems raised in the above-mentioned background technology. The Fenton-like reaction of the humic acid-activated PMS of the present invention produces strong oxidizing substances such as hydroxyl free radicals, which can efficiently remove acetaminophen in water. Compared with the transmission-activated PMS technology, the present invention does not require the addition of metal catalysts, utilizes the energy of visible light, does not require other energy inputs such as heat, electricity, ultraviolet light, or inputs of chemicals such as alkali, and is more environmentally friendly. In order to achieve the above-mentioned purpose, the present invention is realized through the following technical scheme: a method for removing acetaminophen in water based on visible light-excited humic acid to activate PMS, the method uses visible light to excite humic acid to activate PMS to produce hydroxyl radical strong oxidizing substances, which are used to remove acetaminophen in water. In this system, humic acid has photocatalytic activity on organic pollutants. The humic acid is used to excite PMS to produce reactive substances, which produce a large amount of reactive oxygen under light, react with the organic pollutant APAP, and accelerate the degradation of organic pollutants. The reactive substances produced by activating PMS are mainly singlet oxygen, and also include superoxide anions, hydroxyl radicals, etc.

[0012] Furthermore, a verification process of the method is also included, including the following steps:

[0013] Step 1: adding the purified humic acid and PMS into a water sample containing acetaminophen, and placing it under visible light for reaction;

[0014] Step 2: centrifuge or filter the sample in step 1, and take the supernatant or filtrate for analysis;

[0015] Step 3: Add an equal volume of methanol to the solution centrifuged or filtered in step 2 to quench unreacted PMS, and then analyze the solution by high performance liquid chromatography to determine the concentration of acetaminophen using a standard curve.

[0016] Furthermore, the lighting conditions in step 1 are: the light source is a blue light LED (power 18W) with a central wavelength of 460nm-465nm.

[0017] Furthermore, the determination conditions of the HPLC are as follows: using HPLC-UV detector to analyze the target components in the sample, and the chromatographic column is a ZORBAX SB-C18 chromatographic column (150 mm×4.6 mm, 5 μm).

[0018] Furthermore, the mobile phase: liquid A is ammonium acetate aqueous solution (10 mmol / L), liquid B is chromatography grade methanol, and the volume ratio of ammonium acetate aqueous solution to methanol is 8:2, and 0.2% trifluoroacetic acid is added to the mobile phase to improve the tailing of the APAP chromatographic peak.

[0019] Furthermore, the measurement conditions of the HPLC also include: flow rate of 1.0 mL / min; column temperature of 25° C.; injection volume of 20 μL; detection wavelength (DAD signal): 254 nm; retention time of 4-acetylaminophenol is about 4 min; and external standard method is used for quantitative analysis.

[0020] Furthermore, the step 1 also includes purifying the crude humic acid, and the purification of the humic acid includes the following process: weighing the humic acid and adding NaOH, heating and stirring, filtering to remove insoluble impurities, and cooling to room temperature.

[0021] Furthermore, concentrated hydrochloric acid is added to the filtered humic acid solution to adjust the pH value, and a flocculent precipitate is obtained, which is allowed to stand. After the precipitate is aggregated, it is placed in a centrifuge for centrifugal treatment, and the supernatant is discarded to obtain purified humic acid without fulvic acid.

[0022] Further, the purified humic acid is freeze-dried to prepare a humic acid mother solution which is stored in a refrigerator for later use; Step 3: Calculate the residual rate (C) of acetaminophen at different reaction times by the concentration change before and after the reaction.t / C0).

[0023] Furthermore, it also includes the determination of the optimal reaction conditions: in the catalytic system, phosphate buffer is used to adjust the pH value of the solution, and the effect of HA activation PMS degradation of APAP by visible light irradiation is best in acidic conditions, weakened in alkaline conditions, and maintains good activity in neutral conditions.

[0024] Beneficial effects of the present invention:

[0025] 1. The method for removing acetaminophen from water based on visible light-excited humic acid activation of PMS promotes the activation of PMS by adding a suitable photosensitizer to the system in order to promote the degradation of the substrate. The humic acid excited after absorbing visible light can stimulate PMS to produce reactive substances to oxidize APAP. These reactive oxidizing substances include singlet oxygen, superoxide anions and hydroxyl radicals. Using humic acid to activate PMS and degrade APAP under visible light is a green and efficient method with high practical applicability.

[0026] 2. The method for removing acetaminophen from water based on humic acid visible light activation of PMS uses humic acid to activate PMS to produce oxidizing substances such as singlet oxygen, which can effectively remove acetaminophen from water. It does not require the addition of metal catalysts and uses the energy of visible light. It does not require other energy inputs such as heat, electricity, ultraviolet light, or chemicals such as alkali. It is green and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Color comparison of different concentrations of HA (5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L) at pH = 7;

[0028] Figure 2 (c) The APAP degradation experiment was performed by activating PMS (0.5 g / L) with HA (10 mg / L) under visible light at different solution pH values ​​(pH = 3, 5, 7, 9). The curve shows the change of APAP concentration over time. (d) The APAP degradation experiment was performed by activating PMS (0.5 g / L) with HA (10 mg / L) under light protection at different solution pH values ​​(pH = 3, 5, 7, 9). The curve shows the change of APAP concentration over time.

[0029] Figure 3 When pH=7, visible light irradiates HA (10 mg / L) to activate PMS with different concentrations to degrade APAP. The curve shows the change of APAP concentration over time.

[0030] Figure 4 The experimental results of detecting singlet oxygen in the reaction system using electron paramagnetic resonance (EPR) technology in the embodiments of the present invention;

[0031] Figure 5 In the present invention, the effect of adding different quenchers on the degradation of APAP in the APAP degradation experiment under the condition of pH=7 and HA (10 mg / L) activated by visible light irradiation and PMS (0.5 g / L) was shown;

[0032] Figure 6 (a) When pH = 7, HA (10 mg / L) or PMS (0.5 g

[0033] (a) The effect of the addition of HA (10 mg / L) or PMS (0.5 g / L) on the degradation of APAP at pH = 7, and the curve shows the change of APAP concentration over time. (b) At pH = 7, under dark conditions, the effect of the addition of HA (10 mg / L) or PMS (0.5 g / L) on the degradation of APAP. The curve shows the change of APAP concentration over time. (c) At pH = 7, the degradation of APAP by HA activated PMS (0.5 g / L) with different concentrations under visible light irradiation. The curve shows the change of APAP concentration over time. (d) At pH = 7, the degradation of APAP by HA activated PMS (0.5 g / L) with different concentrations under dark conditions. The curve shows the change of APAP concentration over time. DETAILED DESCRIPTION

[0034] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0035] See also Figures 1 to 6 The present invention provides the following technical solution: a method for removing acetaminophen from water based on visible light-excited humic acid and activated PMS, which specifically comprises the following steps: (1) adding purified humic acid and PMS to a water sample containing acetaminophen, and placing it under visible light irradiation for reaction (light source center wavelength: 460nm-465nm; light source color: blue light LED, power 18W),

[0036] (2) centrifuging or filtering the sample in step (1), and taking the supernatant or filtrate for analysis;

[0037] (3) adding an equal volume of methanol to the solution after centrifugation or filtration in step (2) to quench unreacted PMS, and then measuring the solution by high performance liquid chromatography, measuring the concentration of acetaminophen by a standard curve, and calculating the residual rate C of acetaminophen at different reaction times by the change in the concentration of acetaminophen before and after the reaction. t / C0;

[0038] The conditions for the HPLC determination are as follows: the target components in the sample are analyzed by HPLC-UV detector, the chromatographic column is ZORBAX SB-C18 chromatographic column (150mm×4.6mm, 5μm); the mobile phase is: liquid A is ammonium acetate aqueous solution (10mmol / L), liquid B is chromatographic grade methanol, the volume ratio of ammonium acetate aqueous solution to methanol is 8:2, and 0.2% trifluoroacetic acid is added to the mobile phase to improve the tailing of the APAP chromatographic peak; the flow rate is 1.0mL / min; the column temperature is 25℃; the injection volume is 20μL. The detection wavelength (DAD signal): 254nm; the retention time of acetylaminophenol is about 4min; the external standard method is used for quantitative analysis.

[0039] In the above scheme, humic acid is used to activate PMS to produce singlet oxygen and other oxidizing substances, so as to efficiently remove acetaminophen in water. Compared with the transmission activation PMS technology, the present invention does not require the addition of metal catalysts, utilizes the energy of visible light, does not require other energy inputs such as heat, electricity, ultraviolet light, or input of chemicals such as acid and alkali, and is more environmentally friendly.

[0040] This embodiment also provides the following specific scheme for explanation:

[0041] 1 Instrumental analysis conditions

[0042] The target components in the sample were analyzed by high performance liquid chromatography-ultraviolet detector, the chromatographic column was ZORBAX SB-C18 chromatographic column (150mm×4.6mm, 5μm); the mobile phase was: liquid A was ammonium acetate aqueous solution (10mmol / L), liquid B was chromatographic grade methanol, the volume ratio of ammonium acetate solution to methanol was 8:2, and 0.2% trifluoroacetic acid was added to the mobile phase to improve the tailing of APAP chromatographic peak; the flow rate was 1.0mL / min; the column temperature was 25℃; the injection volume was 20μL. The detection wavelength (DAD signal): 254nm; the retention time of 4-acetylaminophenol was 4min; the external standard method was used for quantitative analysis.

[0043] 2 Experimental Procedure

[0044] 1. Purify the commercial humic acid. The specific method is as follows: accurately weigh 1.0g humic acid (humic acid), add 0.1M NaOH (100mL), heat to 80℃ and stir for 1h, filter to remove insoluble impurities, and cool to room temperature. Add concentrated hydrochloric acid to the filtrate to adjust pH=1 to obtain a flocculent precipitate, and let it stand. After the precipitate aggregates, put it into a centrifuge (10000 rpm) and run for 5 minutes before taking it out. Discard the supernatant to obtain purified humic acid without fulvic acid. Freeze-dry the purified humic acid (store in liquid nitrogen for 10min~15min, vacuum dry for 24h), prepare a 2.5g / L humic acid mother solution and store it in a refrigerator for use (2℃~8℃).

[0045] 2. Using acetylaminophenol (APAP) as a substrate, the degradation rate under the conditions of humic acid / light / PMS was explored and the degradation conditions were optimized. A photoreaction device (band: 460nm-465nm; light source color: blue light) was used as a light source for visible light. The reaction conditions were room temperature. Before the start of the photoreaction, humic acid suspension, acetaminophenol and PMS were added to the buffer solution in sequence. The start of light irradiation and (or) the addition of PMS mother liquor was used as the reaction timing starting point. A certain volume of the suspension was drawn at intervals, and after filtering with a needle filter (material: nylon 66; diameter: 13mm; pore size: 0.22μm), a certain amount of filtrate was taken and added to the same volume of methanol for quenching. Finally, the concentration of the substrate APAP was detected by high performance liquid chromatography.

[0046] 3. Preparation of mother liquor

[0047] Preparation of APAP mother solution: Dissolve 30.0 mg APAP in water and make up to volume with a 100 mL volumetric flask. Store in a refrigerator. The concentration of the mother solution is 300 mg / L.

[0048] Preparation of humic acid mother solution: Dissolve 250.0 mg APAP in water and make up to volume with a 100 mL volumetric flask. Store in a refrigerator. The mother solution concentration is 2.5 g / L.

[0049] Preparation of phosphate buffer solution (PB): The concentration of potassium dihydrogen phosphate and disodium hydrogen phosphate mother liquors was 0.067 mol / L, the concentration of sodium hydroxide mother liquor was 0.1 mol / L, and the concentration of phosphoric acid was 14.7 mol / L. Phosphate buffer solutions (PB) with pH = 3, 5, 7, and 9 were prepared using a pH meter.

[0050] Preparation of PMS mother solution: Accurately weigh 10.0g PMS, dissolve it in water, and use a 500mL volumetric flask to make up the volume. Store it in a refrigerator, and the mother solution concentration is 20g / L.

[0051] Preparation of ammonium acetate solution: accurately weigh 0.7708g of ammonium acetate, add 1L of water to dissolve, and add 2mL of trifluoroacetic acid. Shake evenly and ultrasonicate for 5 minutes, filter with a solvent filter (0.22μm), and continue ultrasonicate for 5 minutes. Methanol is chromatographic grade methanol, add 2‰ of trifluoroacetic acid, and ultrasonicate for 5 minutes.

[0052] 3 Results Analysis

[0053] When there is visible light, under the reaction conditions of system pH=7, humic acid (10 mg / L), APAP (30 mg / L), PMS (0.5 g / L), 0.5 mL of the reaction stock solution was taken at time intervals of 0 min, 30 min, 60 min, 90 min, 120 min, and 180 min. After filtering, 0.3 mL was taken and mixed with an equal volume of methanol and the concentration of APAP was detected by HPLC. The experimental results are as follows Figure 6 a. Under the reaction conditions, the degradation rate of APAP by the system was about 90% after 3 hours.

[0054] Under the reaction conditions of system pH=7, humic acid (10 mg / L), APAP (30 mg / L), and PMS (0.5 g / L), the results of APAP removal by the system without light were investigated. Figure 6 As shown in b.

[0055] When there is visible light, the effect of different concentrations of humic acid on the degradation behavior of APAP in the system was investigated under the reaction conditions of system pH = 7, APAP (30 mg / L), and PMS (0.5 g / L). The results are as follows: Figure 6 C, Figure 6 d is Figure 6 c without visible light conditions.

[0056] When the humic acid concentration was 10 mg / L, the degradation effect of the system on APAP was the best, and the rate constant reached 0.019 min -1 The degradation effects of humic acid at 10mg / mL and 15mg / mL on APAP were similar. The humic acid with the highest concentration had the worst degradation effect. Possible reasons: When the humic acid concentration is moderate, the solution is transparent yellow-brown, which is conducive to the absorption of light by the system; when the concentration is high, the color of the solution is significantly darker, which is not conducive to the penetration of light, thus slightly reducing the degradation rate of APAP. Color contrast Figure 1 As shown (5mg / L, 10mg / L, 15mg / L, 20mg / L respectively).

[0057] exist Figure 2In the figure, ab shows the color change of the solution before and after the reaction of humic acid (10 mg / L), APAP (30 mg / L), and PMS (0.5 g / L) under different pH values ​​(from left to right, pH = 3, 5, 7, 9) under light; Figure cd shows the effect of the presence or absence of light on the degradation of APAP in the reaction of humic acid (10 mg / mL), APAP (30 mg / mL), and PMS (0.5 g / L) under different pH values ​​(pH = 3, 5, 7, 9). From the comparison of Figures cd, it can be found that visible light irradiation has a great influence on the reaction system, and the reaction system has almost no ability to remove APAP in the dark. Figure C compares the effect of visible light irradiation on HA activation of PMS to degrade APAP under different pH values ​​(using phosphate buffer to adjust the pH value of the solution). The effect is better under neutral conditions (pH = 7) and worse under alkaline conditions (pH = 9). In an acidic solution (pH=3,5), APAP in the solution was completely removed within 60 minutes, and the reaction was rapid. However, HA aggregated and produced floccules during the activation of PMS under visible light irradiation, and the system was unstable. In general, the method of removing APAP by activating PMS with HA under visible light irradiation is suitable for neutral and alkaline water bodies, but not for acidic water bodies. Considering the removal effect and system stability, the best performance was achieved under neutral conditions.

[0058] The results of the effects of different concentrations of PMS (0.1 mL, 0.25 mL, 0.4 mL, 0.5 mL) on the degradation of APAP in the reaction system of humic acid (10 mg / mL) and APAP (30 mg / mL) under the condition of light are shown in the figure. Figure 3 As shown in the figure, the experimental results show that the APAP removal effect is good when the PMS concentration is moderate. The reaction rate constant k can be used to measure the speed of the reaction. The larger the value, the faster the reaction. Using the first-order kinetic model, R 2 Represents the goodness of fit. The closer it is to 1, the more the actual kinetic behavior conforms to the expected kinetic model.

[0059] In addition, Figure 4 In the electron paramagnetic resonance (EPR) experiment, TEMP was used to detect singlet oxygen in the system. (a) pH = 7,0, at 0 degrees Celsius, PMS = 0.5g / L, HA = 10mg / L, 2,2,6,6-tetramethylpiperidine-hydrochloride (TEMP) (2% v / v, phosphate buffer solution as solvent) was added to detect singlet oxygen. The entire system was 5ml. After different illumination times (gradually accumulated to 8 minutes), the EPR signal of the system. The experimental results show that with the extension of illumination, a large amount of singlet oxygen is generated in the system. (The signal comes from the product of the reaction between singlet oxygen and TEMP);

[0060] pass Figure 5It shows that regardless of HA, the main active intermediate in the reaction process is singlet oxygen, followed by hydroxyl radicals and superoxide anions, and the contribution of sulfate radicals is not obvious. When pH = 7, the effect of adding different quenchers on the reaction system. The initial concentration of APAP is 30 mg / L, and the specific information of other conditions is shown in the legend (reaction under light, the light source is blue light LED). The added quenchers are SOD (mainly capture superoxide anions), tert-butyl alcohol (mainly capture hydroxyl radicals), isopropanol (mainly capture hydroxyl radicals and sulfate radicals), and sodium azide (mainly capture singlet oxygen). The quenchers of these active oxygen species and the corresponding active oxygen species have high reactivity. After adding them to the reaction system, the quenchers can consume the corresponding oxidative active species, thereby affecting the reaction of the latter with APAP. The results of the quenching experiment are often compared with the experimental results without the addition of quenchers to analyze the contribution of the corresponding oxidative active species in the pollutant removal reaction. The oxidative active species in the PMS system often include hydroxyl radicals, singlet oxygen, superoxide anions, sulfate radicals, etc. From our experimental results, the addition of singlet oxygen quencher, sodium azide, has the greatest impact on the kinetics of APAP oxidation removal in the system, and the kinetic constant is reduced the most, by about 90%. Therefore, singlet oxygen is the most important oxidative active species. The EPR experiment also detected obvious singlet oxygen signals, and the two experimental results are consistent; hydroxyl radicals and superoxide anions also contribute to a certain extent, and are also oxidative active species in the system. Comparing the results of adding tert-butyl alcohol (mainly capturing hydroxyl radicals) and isopropanol (mainly capturing hydroxyl radicals and sulfate radicals), the two show similar kinetic constants, indicating that the contribution of sulfate radicals is very small.

[0061] The experimental results are shown in Figure 6 , from the comparison of Figures a and b, it can be found that APAP is stable under visible light; although PMS is an oxidant, if HA is not added, PMS alone has almost no ability to oxidize and remove APAP, whether in the presence of light or in the absence of light. HA has a certain ability to photosensitize and remove APAP under visible light, but the effect is general (APAP+light+HA(10mg / L)); however, HA can well activate PMS under light to decompose and oxidize APAP (APAP+light+PMS(0.5g / L)+HA(10mg / L)), and the catalytic effect of HA on PMS is greatly affected by light. If it is protected from light, PMS cannot be activated by HA. )

[0062] Figure C, this example analyzes the effect of HA concentration on the activation of PMS under light, and finds that there is little difference in HA concentration within the range of 5-15 mg / L. If the concentration is further increased, the effect decreases. From the comparison results of the reaction rate constants, the k value under HA (10 mg / L) is the largest, and the effect is the best.

[0063] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention.

[0064] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for removing acetaminophen from water based on visible light-excited humic acid activation of PMS, characterized in that: This method uses humic acid under visible light to activate PMS to undergo a decomposition reaction to produce oxidizing substances such as singlet oxygen, which is used to remove acetaminophen in water. In this system, humic acid has photosensitivity under visible light. The photoexcited humic acid can sensitize PMS to produce reactive substances, such as a large amount of reactive oxygen, which reacts with the organic pollutant APAP to rapidly degrade APAP. The reactive substances in the whole process are mainly singlet oxygen, and also include superoxide anions and hydroxyl radicals.

2. The method for removing acetaminophen from water based on visible light-excited humic acid activation of PMS according to claim 1 further comprises a verification process for the method, comprising the following steps: Step 1: adding the purified humic acid and PMS into a water sample containing acetaminophen, and placing it under visible light for reaction; Step 2: centrifuge or filter the sample in step 1, and take the supernatant or filtrate for analysis; Step 3: Add an equal volume of methanol to the solution centrifuged or filtered in step 2 to quench unreacted PMS, and then analyze the solution by high performance liquid chromatography to determine the concentration of acetaminophen using a standard curve.

3. A method for removing acetaminophen from water based on visible light-excited humic acid activation of PMS according to claim 2, characterized in that: The illumination condition in step 1 is: the light source is a blue light LED with a central wavelength of 460nm-465nm (power 18W).

4. The method for removing acetaminophen from water by activating PMS with humic acid based on visible light excitation according to claim 2, characterized in that: The determination conditions of the high performance liquid chromatography are as follows: using a high performance liquid chromatography-ultraviolet detector to analyze the target components in the sample, and the chromatographic column is a ZORBAX SB-C18 chromatographic column (150 mm×4.6 mm, 5 μm).

5. The method for removing acetaminophen from water by activating PMS with humic acid based on visible light excitation according to claim 4, characterized in that: Mobile phase: Liquid A is ammonium acetate aqueous solution (10 mmol / L), liquid B is chromatography grade methanol, and the volume ratio of ammonium acetate aqueous solution to methanol is 8:

2. In addition, 0.2% trifluoroacetic acid is added to the mobile phase to improve the tailing of the APAP chromatographic peak.

6. The method for removing acetaminophen from water by activating PMS with humic acid based on visible light excitation according to claim 5, characterized in that: The measurement conditions of the high performance liquid chromatography also include: a flow rate of 1.0 mL / min; a column temperature of 25° C.; an injection volume of 20 μL; a detection wavelength (DAD signal): 254 nm; a retention time of 4-acetylaminophenol of about 4 minutes; and an external standard method for quantitative analysis.

7. The method for removing acetaminophen from water by activating PMS with humic acid using visible light according to claim 2, characterized in that: The step 1 also includes purifying the crude humic acid. The purification of the humic acid includes the following process: weighing the humic acid, adding NaOH, heating and stirring, filtering to remove insoluble impurities, and cooling to room temperature.

8. The method for removing acetaminophen from water by activating PMS with humic acid using visible light according to claim 7, characterized in that: Concentrated hydrochloric acid is added to the filtered humic acid solution to adjust the pH value, and a flocculent precipitate is obtained, which is then allowed to stand; After the precipitate is aggregated, it is placed in a centrifuge for centrifugation, and the supernatant is discarded to obtain purified humic acid without fulvic acid.

9. The method for removing acetaminophen from water by activating PMS with humic acid using visible light according to claim 8, characterized in that: The purified humic acid is freeze-dried to prepare a humic acid mother solution which is stored in a refrigerator for later use; Step 3: Calculate the residual rate (C) of acetaminophen at different reaction times by the change in acetaminophen concentration before and after the reaction. t / C0).

10. The method for removing acetaminophen from water by activating PMS with humic acid based on visible light excitation according to claim 9, characterized in that: It also includes the determination of the optimal reaction conditions: phosphate buffer is used to adjust the pH value of the solution in the catalytic system, and the effect of humic acid activation of PMS to degrade APAP under visible light irradiation is best in acidic conditions, weakened in alkaline conditions, and maintains good activity in neutral conditions.

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