Riboflavin-mediated nano-zero-valent iron / peracetic acid enhanced method for removing pollutants from water

Abstract

The present invention provides a method for riboflavin-mediated nano zero-valent iron / peracetic acid to enhance the removal of pollutants in water. The excellent performance of riboflavin in the electron transfer process is used to significantly improve the activation efficiency of peracetic acid in the nano zero-valent iron / peracetic acid system, and achieve efficient and rapid degradation of norfloxacin, a pollutant in water. By using nZVI as an activator, the activation energy barrier of PAA is significantly reduced, and its decomposition to produce strong oxidizing free radicals is accelerated. At the same time, RF is introduced to enhance electron transfer, further improving the activation efficiency of PAA. The present invention not only improves the pollutant degradation efficiency, but also reduces the emission of chemical oxygen demand. The RF / nZVI / PAA process constructed based on the RF electron transfer characteristics significantly shortens the pollutant degradation time. It only takes 30 minutes to efficiently degrade norfloxacin, which is easy to operate, has a high degradation rate, low energy consumption, and the catalyst can be recycled.

Description

Technical Field

[0001] The invention belongs to the application field of advanced oxidation sewage treatment technology, and specifically relates to a method for removing pollutants in water by using riboflavin-mediated nano zero-valent iron / peracetic acid enhanced methods. Background Art

[0002] With the continuous advancement of urbanization and industrialization, new pollutants that are difficult to degrade, such as drugs, are frequently detected in various wastewaters, posing a serious threat to the ecosystem and human health. Drugs are difficult to be completely absorbed and metabolized after being used by humans or animals. Most of them will be excreted from the body into the water environment in the form of the original parent or conjugated structure, which not only increases the complexity of water treatment, but also poses severe challenges to the sustainable recycling of water resources. Therefore, it is crucial to develop efficient and economical water purification technologies. Among the many treatment technologies, advanced oxidation processes have become one of the effective means to degrade pharmaceutical pollutants in water because they can produce strong oxidizing free radicals to attack and decompose organic pollutants in water.

[0003] As an organic peracid, PAA has been widely used in the field of advanced oxidation process for wastewater purification in recent years due to its strong oxidizing ability and environmental friendliness. However, in actual application, when PAA is used alone for treatment, a high dosage is often required to achieve a good degradation effect. If it is not properly controlled, it will lead to an excess of chemical oxygen demand in the effluent. Therefore, in recent years, various methods including physical methods (light irradiation, heat, non-thermal plasma, etc.), catalysts (metal ions, activated carbon, etc.) and other methods such as electrochemistry have been used to activate PAA to improve the degradation efficiency of pollutants. After activation, PAA will produce carbon-centered organic free radicals (RC·) in addition to ·OH. These organic free radicals are more selective than ·OH and are less affected by the water quality background, which is conducive to the efficient degradation of difficult-to-degrade pollutants in wastewater.

[0004] Document CN116002842B uses carbon nanotubes loaded with transition metals as activators of PAA to achieve efficient degradation of carbamazepine. Document CN117699923A uses electrochemical synergistic carbon nanotubes to activate PAA to efficiently degrade organic micropollutants. However, these activation methods have the problems of poor stability, difficult recycling, poor reusability of transition metal catalysts, complex material preparation, additional energy consumption, and high degradation costs, making them difficult to be applied on a large scale in actual wastewater treatment.

[0005] Therefore, it is an urgent technical problem to develop a new method for activating PAA to efficiently degrade organic micropollutants, and this method can reduce chemical oxygen demand emissions, shorten pollutant degradation time, be easy to operate, have a high degradation rate, low energy consumption, and recyclable catalysts. Summary of the invention

[0006] In view of the above shortcomings of the prior art, the present invention provides a method for riboflavin-mediated nano zero-valent iron / peracetic acid enhanced removal of pollutants in water, using the advantages of nZVI, such as low reduction potential, low cost, easy availability, environmental friendliness and easy secondary utilization, as an activator of PAA, so that it can effectively reduce the activation energy barrier of PAA and promote its decomposition to produce strong oxidizing free radicals. Combined with RF's good electron transfer function, the economical and efficient degradation of pollutants is achieved.

[0007] To achieve the above object, the present invention provides a method for riboflavin-mediated nano-zero-valent iron / peracetic acid enhanced removal of pollutants in water, which is based on the electron transfer properties of riboflavin.

[0008] Furthermore, the method of riboflavin-mediated nano-zero-valent iron / peracetic acid for strengthening pollutants in water of the present invention comprises the following steps:

[0009] Step S1, riboflavin RF addition:

[0010] Add appropriate amount of RF to wastewater containing pollutants;

[0011] Step S2, adding peracetic acid PAA:

[0012] Adding a certain amount of peracetic acid PAA to the wastewater to which riboflavin has been added in step S1;

[0013] Step S3, degradation of pollutants in sewage:

[0014] The wastewater obtained in step S2 is placed in a rotary photochemical reactor, the pH of the reaction system is adjusted at room temperature, and a certain amount of catalyst nano zero-valent iron nZVI is added to achieve the degradation of pollutants.

[0015] Further, in step S1, the dosage of riboflavin is 0.2-2 mg / L;

[0016] The wastewater containing pollutants is the pharmaceutical pollutant norfloxacin wastewater, and its concentration is 1 to 10 mg / L;

[0017] The concentration of peracetic acid in the wastewater in step S2 is 3-15 mg / L;

[0018] In step S3, the dosage of nano zero-valent iron is 5-60 mg / L, the pH is adjusted to 3.0-10.0, and the degradation time is 60 min.

[0019] Furthermore, after the primary degradation process is completed, the catalyst nano zero-valent iron regenerates nZVI, and then nZVI is reintroduced into the RF / nZVI / PAA system for use;

[0020] The regeneration process of nZVI is as follows: after one reaction, the nZVI is washed with ethanol and ultrapure water, and the washed nZVI is naturally air-dried to remove residual moisture for use in cycle testing.

[0021] Furthermore, the regeneration process of nZVI is as follows: first, transfer the nZVI after a reaction to a 100mL beaker, add 40mL of ethanol, and stir at a speed of 30-50r / min for 5min, then transfer the mixture of nZVI and ethanol to a sand core filter device for nZVI separation. During this process, rinse the inner wall of the beaker with 10mL of ethanol to ensure that there is no nZVI residue in the beaker. Repeat the above steps three times for deep cleaning; secondly, after washing with ethanol, use ultrapure water to wash and separate nZVI three times. The washing steps are the same as those for ethanol washing. The total amount of ultrapure water used each time is 50mL, and a sand core filter device is used for nZVI separation; thirdly, the washed nZVI is naturally air-dried to remove residual moisture for cycle testing.

[0022] Furthermore, in the evaluation method of pollutant degradation performance of the enhanced nZVI / PAA system, the verification method of the electron transfer characteristics of riboflavin is as follows:

[0023] (1) Verification of RF’s electronic transfer characteristics:

[0024] Electrochemical measurements of electrolyte solutions during pollutant degradation in the RF / nZVI / PAA system and the nZVI / PAA system were performed using an electrochemical workstation to evaluate the role of RF in electron transfer in the RF / nZVI / PAA system.

[0025] (2) Through free radical quenching experiments and combined with pseudo-first-order kinetics, the degradation process was fitted and the effect of RF-enhanced free radical generation on pollutant degradation in the RF / nZVI / PAA system was quantitatively analyzed.

[0026] Furthermore, in step (1), the electrochemical workstation uses a single-chamber reaction cell and a three-electrode system, the working electrode is a glassy carbon electrode, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum electrode; the electrochemical test method is cyclic voltammetry, and the reference scanning parameters include initial potential -0.7V, high potential 0.1V, low potential -0.7V, final potential 0V, positive initial scan, scan rate 0.001V / s, scan number 4, sampling time 0.001V, static time 10s, sensitivity 1.0×10 -4 A / V.

[0027] Furthermore, in step (2), the free radical quenching experiment requires the addition of 100 mM of a quencher to the solution before the experiment to quench the corresponding free radical contribution analysis, using tert-butyl alcohol (TBA) as a scavenger of ·OH and carbon-centered free radicals (RC·), and furfuryl alcohol (FFA) as a singlet oxygen scavenger. 1 O2 scavenger.

[0028] Furthermore, in step (2), first, the degradation rate constant k of each system is obtained by pseudo-first-order kinetic equation. obs , as shown in Formula 1:

[0029]

[0030] Among them, k obs is the degradation rate constant (min -1 ), C0 is the initial concentration of norfloxacin (mg / L), and C is the concentration of norfloxacin during the degradation process (mg / L).

[0031] Furthermore, the contribution of the free radical quenching test results to the degradation of norfloxacin was calculated according to the following formulas (2) to (7):

[0032]

[0033] k nZVI adsorption =k nZVI (3)

[0034] k PAA oxidation =k PAA (4)

[0035] k ·OH =k RF / nZVI / PAA -k RF / nZVI / PAA+TBA (5)

[0036]

[0037]

[0038] Among them, k RF / nZVI / PAA , k nZVI adsorption That is k nZVI , k PAA oxidation That is k PAA , k ·OH , k R-C· and They are RF / nZVI / PAA system, nZVI adsorption alone, PAA oxidation alone, ·OH oxidation, RC· oxidation and 1 Norfloxacin degradation rate constant by O2 oxidation; k RF / nZVI / PAA+TBAis the degradation rate constant of norfloxacin after adding TBA to the RF / nZVI / PAA system; k RF / nZVI / PAA+FFA is the degradation rate constant of norfloxacin after adding FFA in the RF / nZVI / PAA system.

[0039] Furthermore, the free radical contribution of RF enhancement is calculated according to the following formulas (8) to (10):

[0040] k ·OH =k RF / nZVI / PAA -k RF / nZVI / PAA+TBA -k nZVI / PAA +k nZVI / PAA+TBA (8)

[0041] k R-C· =k RF / nZVI / PAA+TBA -k nZVI / PAA+TBA -k RF / nZVI / PAA +k RF / nZVI / PAA+FFA +k nZVI / PAA -k nZVI / PAA+FFA (9)

[0042]

[0043] Among them, k nZVI / PAA is the degradation rate constant of norfloxacin in the nZVI / PAA system; k nZVI / PAA+TBA is the degradation rate constant of norfloxacin after adding TBA to the nZVI / PAA system; k nZVI / PAA+FFA is the degradation rate constant of norfloxacin after adding FFA to the nZVI / PAA system; k ·OH , k R-C· and RF promoted OH oxidation, RC promoted oxidation and 1 The degradation rate constant of O2 oxidation. The other parameters in this formula have the same meanings as those in formulas (3) to (7).

[0044] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0045] 1) The present invention significantly reduces the activation energy barrier of PAA by using nZVI as an activator, accelerating its decomposition to produce strong oxidizing free radicals. At the same time, RF is introduced to enhance electron transfer, further improving the activation efficiency of PAA. This method not only improves the pollutant degradation efficiency, but also reduces the emission of chemical oxygen demand, providing an economical and sustainable new technology for wastewater treatment.

[0046] 2) The present invention significantly enhances the degradation effect of the nZVI / PAA system on norfloxacin through the electron transfer effect of RF.

[0047] 3) Compared with the existing nZVI / PAA process, electrochemical and transition metal ion activated PAA process, the RF / nZVI / PAA process constructed based on the RF electron transfer characteristics of the present invention significantly shortens the pollutant degradation time and can efficiently degrade norfloxacin in only 30 minutes. It is easy to operate, has a high degradation rate, low energy consumption, and the catalyst can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The figure is a diagram showing the degradation effect of norfloxacin in Example 1 and Comparative Examples 1-4.

[0049] Figure 2 Cyclic voltammetry curves of nZVI / PAA system with and without RF mediation in Example 1 and Comparative Example 1.

[0050] Figure 3 This is a graph showing the contribution of RF-enhanced free radical generation to the degradation of norfloxacin in the RF / nZVI / PAA system in Example 1.

[0051] Figure 4 This is a diagram showing the effect of recycling nZVI and degrading norfloxacin in the RF / nZVI / PAA system in Example 1.

[0052] Figure 5 The degradation effect of norfloxacin by the RF / nZVI / PAA system at different PAA dosages in Example 2 is shown. Figure 6 The degradation effect of norfloxacin by the RF / nZVI / PAA system at different nZVI dosages in Example 3.

[0053] Figure 7 This is a diagram showing the degradation effect of norfloxacin on the RF / nZVI / PAA system at different RF dosages in Example 4.

[0054] Figure 8 This is a diagram showing the degradation effect of norfloxacin by the RF / nZVI / PAA system at different initial norfloxacin concentrations in Example 5. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0056] The technical solution of the present invention is further explained below in conjunction with implementation cases.

[0057] Example 1

[0058] (1) At room temperature, RF and PAA were added to a norfloxacin solution to make the concentrations of norfloxacin, RF and PAA in the solution 5 mg / L, 1 mg / L and 10 mg / L, respectively. After adjusting the initial pH value of the solution to 4.0 with 1 mol / L HCl, nZVI was added and mixed to obtain a reaction solution. The dosage of nZVI in the reaction solution was 20 mg / L. The concentrations of RF and PAA were adjusted to 0, 1, 3, 5, 10,

[0059] 5 mL of samples were taken at 15, 20, 30, 45, and 60 min, respectively, and filtered through a 0.22 μm PTFE filter membrane for norfloxacin concentration detection and electrochemical testing. The concentration of norfloxacin was determined using high performance liquid chromatography HPLC (Agilent Technologies 1200 Series, USA).

[0060] (2) When conducting free radical quenching experiments, 100 mM of quencher was added to the solution before the experiment to quench the corresponding free radical contribution analysis. The quencher tert-butyl alcohol was used as a scavenger of ·OH, and the quencher furfuryl alcohol was used as a scavenger of singlet oxygen ( 1 O2) scavenger. The system was obtained using pseudo-first-order kinetic equation

[0061] System degradation rate constant k:

[0062]

[0063] Among them, k obs is the degradation rate constant (min -1 ), C0 is the initial concentration of norfloxacin (mg / L), and C is the concentration of norfloxacin during the degradation process (mg / L).

[0064] After the primary degradation of norfloxacin was completed, the regeneration process of nZVI was as follows: first, the nZVI after the primary reaction was transferred to a 100 mL beaker, 40 mL of ethanol was added, and stirred at a speed of 40 r / min for 5 min, and then the mixture of nZVI and ethanol was transferred to a sand core filter device for nZVI separation. During this process, the inner wall of the beaker was rinsed with 10 mL of ethanol to ensure that there was no nZVI residue in the beaker. The above steps were repeated three times for deep cleaning;

[0065] Secondly, after washing with ethanol, nZVI was washed and separated three times with ultrapure water. The washing steps were the same as those for washing with ethanol. The total amount of ultrapure water used each time was 50 mL. A sand core filter device was used to separate nZVI.

[0066] Third, the washed nZVI was naturally air-dried to remove residual moisture for recycling testing. The recovered nZVI was put into the RF / nZVI / PAA system again (experimental conditions: initial concentration of norfloxacin = 5 mg / L, PAA dosage = 10 mg / L, nZVI dosage = 20 mg / L, RF dosage = 1 mg / L, initial pH = 4.0) to perform two continuous recycling tests. By comparing the pollutant degradation effect of each cycle, the recycling performance and long-term stability of nZVI were evaluated.

[0067] Comparative Example 1

[0068] Same as Example 1, except that no RF solution was added to the norfloxacin solution, and the group was marked as nZVI / PAA.

[0069] Comparative Example 2

[0070] Same as Example 1, except that only PAA solution was added to the norfloxacin solution, and the group was marked as PAA.

[0071] Comparative Example 3

[0072] Same as Example 1, except that only nZVI solution was added to the norfloxacin solution, and the group was marked as nZVI.

[0073] Comparative Example 4

[0074] Same as Example 1, except that only RF solution was added to the norfloxacin solution, and the group was marked as RF.

[0075] After 30 minutes of reaction in different reaction systems of Example 1 and Comparative Examples 1 to 4, the degradation effects of norfloxacin are shown in Table 1.

[0076] Figure 1 The degradation effects of norfloxacin in Example 1 and Comparative Examples 1-4 are shown in Table 1. Figure 1 It can be seen that the RF / nZVI / PAA system can completely degrade norfloxacin within 30 minutes, while the removal rates of norfloxacin by nZVI adsorption, PAA oxidation and nZVI / PAA combined systems are 5.1%, 25.1% and 40.0% respectively after 30 minutes of treatment, while RF hardly removes norfloxacin. The degradation rates of norfloxacin by Example 1 and Comparative Examples 1-4 are shown in Table 1.

[0077] Table 1

[0078] Reaction system Degradation rate (%) Example 1 RF / nZVI / PAA 100 Comparative Example 1 nZVI / PAA 40.0 Comparative Example 2 PAA 25.1 Comparative Example 3 nV 5.1 Comparative Example 4 RF 0.1

[0079] Figure 2The scanning results of cyclic voltammetry of Example 1 and Comparative Example 1 were obtained by using a bistable electrophoresis instrument (dyy-6c Beijing Junyi Dongfang Electrophoresis Equipment Co., Ltd., China). Figure 2 It can be seen that the maximum current of the RF / nZVI / PAA system (0.334μA) is higher than that of the nZVI / PAA system (0.190μA), which indicates that RF, as an electron shuttle, increases the overall electron flow of the nZVI / PAA system and promotes the electron transfer rate between the systems. The RF / nZVI / PAA system has a pair of reversible redox peaks with a peak potential difference of about 60mV. The peak potential difference of the RF / nZVI / PAA system is significantly reduced compared with that of nZVI / PAA, proving that the charge resistance of the system is reduced after the addition of RF, which accelerates the electron transfer process.

[0080] Figure 3 The contribution of RF to the degradation of norfloxacin by free radicals in the nZVI / PAA system in Example 1 is shown in Table 1. The degradation curve of the reaction with time (t) was plotted, and exponential nonlinear fitting was performed using Excel to obtain the k value based on the pseudo-first-order kinetic equation:

[0081]

[0082] Where, k is the degradation rate constant (min -1 ), C0 is the initial concentration of norfloxacin (mg / L), C is the concentration of norfloxacin during the degradation process (mg / L), and t is the degradation time (min).

[0083] Table 2 lists the degradation rate constants of RF / nZVI / PAA, RF / nZVI / PAA+TBA, RF / nZVI / PAA+FFA, nZVI / PAA, nZVI / PAA+TBA, nZVI / PAA+FFA, nZVI, and PAA systems.

[0084] Table 2

[0085]

[0086] According to the following formula, in the RF / nZVI / PAA system, OH, RC and 1 The degradation rate constants of norfloxacin by O2 were 0.047min -1 、0.057min -1 and 0.007min -1 .

[0087] k ·OH =k RF / nZVI / PAA -k RF / nZVI / PAA+TBA

[0088]

[0089]

[0090] Among them, k ·OH , k R-C· and They are ·OH oxidation, RC· oxidation and 1 Rate constant of norfloxacin degradation by O2 oxidation.

[0091] The RF-enhanced OH oxidation, RC oxidation and 1 The rate constants of norfloxacin degradation by O2 oxidation are 0.36min and 0.56min, respectively. -1 , 0.025min -1 With k = 0.005min -1 .

[0092] k ·OH =k RF / nZVI / PAA -k RF / nZVI / PAA+TBA -k nZVI / PAA +k nZVI / PAA+TBA

[0093] k R-C· =k RF / nZVI / PAA+TBA -k nZVI / PAA+TBA -k RF / nZVI / PAA +k RF / nZVI / PAA+FFA +k nZVI / PAA -k nZVI / PAA+FFA

[0094]

[0095] Among them, k ·OH , k R-C· and RF promoted OH oxidation, RC promoted oxidation and 1 Degradation rate constant for O2 oxidation.

[0096] Depend on Figure 3 As shown in Table 2, RF has the most significant effect on promoting ·OH. After adding RF as an electron shuttle, the additional ·OH accounts for 78.7% of the total ·OH contribution. In terms of RC· production, RF promotes the RC· produced by nZVI / PAA to account for 43.9% of the total RC· contribution. 1 In terms of O2 production, RF promotes the production of nZVI / PAA 1 O2 contribution rate to the total 1O2 contributed 71.5%. The above results show that the addition of RF enhances the generation of free radicals (·OH, RC·, etc.) and strengthens the removal effect of norfloxacin.

[0097] Figure 4 This is the degradation effect diagram of nZVI repeated recycling. Figure 4 It can be seen that after reusing nZVI twice, the removal rate of norfloxacin within 30 minutes was still maintained above 95%, indicating that the nZVI in the system has reusable properties and can be recovered and reused in the actual process to reduce the cost of the process.

[0098] Example 2

[0099] Investigate the effect of PAA dosage on the degradation performance of norfloxacin:

[0100] A norfloxacin solution was prepared, and RF and PAA solutions were added to the norfloxacin solution. After adjusting the initial pH value of the solution to 4.0 with 1 mol / L HCl, nZVI was added and mixed evenly to obtain a reaction solution with a norfloxacin concentration of 5 mg / L, an RF concentration of 1 mg / L, an nZVI dosage of 20 mg / L and a series of different PAA concentrations (respectively 3, 5, 7, 10, and 15 mg / L). 5 mL of the sample was taken at 0, 1, 3, 5, 10, 15, 20, 30, 45, and 60 min, respectively, and filtered through a 0.22 μm PTFE filter membrane to detect the concentration of the remaining norfloxacin (the detection method was the same as in Example 1), and the degradation rate constant (k) under each condition was obtained by a pseudo-first-order kinetic equation. obs ):

[0101]

[0102] Among them, k obs is the degradation rate constant (min -1 ), C0 is the initial concentration of norfloxacin (mg / L), and C is the concentration of norfloxacin during the degradation process (mg / L).

[0103] Effects of different PAA dosages on norfloxacin degradation Figure 5 shown.

[0104] Depend on Figure 5 It can be seen that when the PAA dosage is in the range of 7 to 15 mg / L, norfloxacin can be completely removed within 45 min. The degradation rate constant of norfloxacin gradually increases with the increase of PAA dosage from 7 mg / L to 15 mg / L (from 0.051 min -1 Increased to 0.141min -1 ).

[0105] Example 3

[0106] Investigate the effect of nZVI dosage on the degradation performance of norfloxacin:

[0107] Norfloxacin solution was prepared, RF and PAA solutions were added to the norfloxacin solution, the initial pH value of the solution was adjusted to 4.0 with 1 mol / L HCl, nZVI was added, and the mixture was evenly mixed to obtain reaction solutions with a norfloxacin concentration of 5 mg / L, an RF concentration of 1 mg / L, a PAA concentration of 10 mg / L, and a series of nZVI doses (5, 10, 20, 40, and 60 mg / L, respectively). 5 mL of samples were taken at 0, 1, 3, 5, 10, 15, 20, 30, 45, and 60 min, respectively, and filtered through a 0.22 μm PTFE filter membrane for the detection of the remaining norfloxacin concentration. The degradation rate constant (k) under each condition was obtained by the pseudo-first-order kinetic equation. obs ):

[0108]

[0109] Among them, k obs is the degradation rate constant (min -1 ), C0 is the initial concentration of norfloxacin (mg / L), and C is the concentration of norfloxacin during the degradation process (mg / L).

[0110] Effects of different nZVI dosages on norfloxacin degradation Figure 6 shown.

[0111] Depend on Figure 6 It can be seen that when the dosage of nZVI is greater than 5 mg / L, the RF / nZVI / PAA system can completely remove norfloxacin within 45 min. When the dosage of nZVI increases from 10 mg / L to 20 mg / L, the degradation rate constant increases from 0.082 min to 0.137 min. -1 Increased to 0.111min -1 As the dosage of nZVI increased from 20 mg / L to 60 mg / L, the degradation rate constant increased from 0.111 min -1 Gradually reduced to 0.070min -1 .

[0112] Example 4

[0113] Investigate the effect of RF dosage on the degradation performance of norfloxacin:

[0114] Norfloxacin solution was prepared, RF and PAA solution were added to the norfloxacin solution, the initial pH value of the solution was adjusted to 4.0 with 1 mol / L HCl, nZVI was added, and the mixture was evenly mixed to obtain a reaction solution with a norfloxacin concentration of 5 mg / L, a PAA concentration of 10 mg / L, an nZVI dosage of 20 mg / L, and a series of different RF concentrations (0.2, 0.4, 0.8, 1.0, and 2.0 mg / L, respectively). 5 mL of samples were taken at 0, 1, 3, 5, 10, 15, 20, 30, 45, and 60 min, respectively, and filtered through a 0.22 μm PTFE filter membrane for the detection of the remaining norfloxacin concentration. The degradation rate constant (k) under each condition was obtained by the pseudo-first-order kinetic equation. obs ):

[0115]

[0116] Among them, k obs is the degradation rate constant (min -1 ), C0 is the initial concentration of norfloxacin (mg / L), and C is the concentration of norfloxacin during the degradation process (mg / L).

[0117] Effects of different RF dosages on norfloxacin degradation Figure 7 shown.

[0118] Depend on Figure 7 It can be seen that when the RF dosage is in the range of 0.8-2.0 mg / L, norfloxacin can be completely removed within 30-45 min, and the degradation rate constant is 0.019 min -1 ~0.133min -1 RF is an efficient electron shuttle that can act as a medium for electron transfer. With the increase of RF dosage, the degradation effect may be improved by promoting the reduction of Fe(III) to Fe(II) and maintaining the high efficiency of the catalytic reaction.

[0119] Example 5

[0120] Investigate the effect of initial norfloxacin concentration on degradation performance:

[0121] Norfloxacin solution was prepared, RF and PAA solution were added to the norfloxacin solution, the initial pH value of the solution was adjusted to 4.0 with 1 mol / L HCl, nZVI was added, and mixed evenly to obtain a series of reaction solutions with different norfloxacin concentrations (1, 3, 5, 7, 10 mg / L), RF concentration of 1 mg / L, PAA concentration of 10 mg / L, and nZVI dosage of 20 mg / L. 5 mL of the reaction solution was sampled at 0, 1, 3, 5, 10, 15, 20, 30, 45, and 60 min, respectively, and filtered through a 0.22 μm PTFE filter membrane for the detection of the remaining norfloxacin concentration. The degradation rate constant (k) under each condition was obtained by the pseudo-first-order kinetic equation. obs ):

[0122]

[0123] Among them, k obs is the degradation rate constant (min -1 ), C0 is the initial concentration of norfloxacin (mg / L), and C is the concentration of norfloxacin during the degradation process (mg / L).

[0124] Effects of different initial concentrations on norfloxacin degradation Figure 8 As shown. Figure 8 It can be seen that when the concentration of norfloxacin is in the range of 1-7 mg / L, the complete removal of norfloxacin can be achieved within 15-45 min, and the maximum degradation rate constant is 0.571 min -1 As the initial concentration of norfloxacin increased, the degradation rate constant gradually decreased, and the time required for complete degradation also increased accordingly, which may be caused by the insufficient concentration of active free radicals generated in the system.

[0125] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for enhancing the removal of pollutants from water by riboflavin-mediated nano-zero-valent iron / peracetic acid, characterized in that: The method is based on the electron transfer characteristics of riboflavin and includes the following steps: Step S1, riboflavin RF addition: Add a certain amount of RF to wastewater containing pollutants; Step S2, adding peracetic acid PAA: Adding a certain amount of peracetic acid PAA to the wastewater to which riboflavin has been added in step S1; Step S3, degradation of pollutants in sewage: The wastewater obtained in step S2 is placed in a rotary photochemical reactor, the pH of the reaction system is adjusted at room temperature, and a certain amount of catalyst nano zero-valent iron nZVI is added to achieve the degradation of pollutants; In step S1, the dosage of riboflavin is 0.2-2 mg / L; The wastewater containing pollutants is the pharmaceutical pollutant norfloxacin wastewater, and its concentration is 1 to 10 mg / L; The concentration of peracetic acid in the wastewater in step S2 is 3-15 mg / L; In step S3, the dosage of nano zero-valent iron is 5-60 mg / L, the pH is adjusted to 3.0-10.0, and the degradation time is 60 min.

2. The method for enhancing the removal of pollutants in water by riboflavin-mediated nano-zero-valent iron / peracetic acid according to claim 1, characterized in that: After the primary degradation process is completed, the catalyst nano zero-valent iron regenerates nZVI, and then nZVI is reintroduced into the RF / nZVI / PAA system for use; The regeneration process of nZVI is as follows: after one reaction, the nZVI is washed with ethanol and ultrapure water, and the washed nZVI is naturally air-dried to remove residual moisture for use in cycle testing.

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