A method for water treatment by carbon quantum dots reinforced high-valence metal oxidation

Abstract

The application discloses a carbon quantum dot reinforced high-valence metal oxidation water treatment method, and belongs to the technical field of water treatment. The method comprises the following steps: adding carbon quantum dot solution and potassium permanganate or potassium ferrate into polluted water to be treated in sequence, and treating under stirring for 10-60 minutes, so as to complete the treatment. The application has excellent oxidation efficiency and fast reaction rate, and has excellent pollutant removal effect in the pH 4-8 range. The application also has good efficiency under complex water quality, and is beneficial to application in actual engineering. In the potassium ferrate / carbon quantum dot system, the removal effect of organic pollutants is improved by 10-40%, and the oxidation reaction rate is improved by 1.1-22.8 times. In the potassium permanganate / carbon quantum dot system, the removal effect of organic pollutants is improved by 0.1-6.4 times, the electron transfer efficiency is improved, the utilization efficiency of the oxidant is improved, and the pollutant degradation effect is improved. The application is suitable for water treatment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water treatment; specifically relates to a water treatment method for carbon quantum dots to strengthen high-valence metal oxidation. BACKGROUND

[0002] With the continuous progress of society, human activities have caused more and more environmental pollution problems, especially some organic matters with high risk and potential threat to ecological safety are discharged into water bodies, causing serious water environmental pollution. Advanced oxidation technology is a kind of efficient chemical technology for deep treatment of organic matters. Common oxidants include ozone, persulfate, Fenton system, Fenton-like system and high-valence metal. Among them, high-valence metal oxides represented by ferrate and permanganate are considered as a kind of green, multifunctional and efficient oxidant because of their high oxidation-reduction potential and good adsorption capacity of the reduced products. Although high-valence metal oxidants can oxidize and degrade many kinds of organic pollutants, their efficiency is not high in some reactions. Because of the higher reactivity, a large number of studies focus on using reducing substances to excite high-valence metal oxidants to produce intermediate state active species, such as metal (divalent manganese Mn(II), divalent iron Fe(II), divalent cobalt Co(II)), non-metal (sulfite SO3 2- , thiosulfate S2O3 2- , hydroxylamine NH2OH) and carbon materials (carbon nanotubes, graphene, biochar, hydrothermal carbon). In recent years, with the promotion of the double carbon policy, the recycling of carbon represented by carbon-based catalysts has developed rapidly. Carbon materials can be divided into zero-dimensional (such as carbon quantum dots), one-dimensional (such as carbon nanotubes), two-dimensional (such as graphene) and three-dimensional (such as biochar) according to the dimension. Although characterization experiments and probe compound experiments prove that the carbonyl C=O functional group on one-dimensional, two-dimensional and three-dimensional carbon materials is the active site for exciting high-valence metal oxidants to produce intermediate state active species, the excitation of intermediate state oxidation active species by the carbon materials will consume the oxidant, and in the actual water body, the complex water environment will consume the oxidant, resulting in low utilization efficiency of the oxidant. Therefore, it is necessary to seek more efficient, sustainable and green carbon materials to strengthen high-valence metal oxidants. SUMMARY

[0003] The application aims to solve the above technical problems and provides a water treatment method for carbon quantum dots to strengthen high-valence metal oxidation.

[0004] A kind of carbon quantum dots reinforced high valence metal oxidation water treatment method, is realized according to the following process:

[0005] Carbon quantum dots solution and potassium permanganate or potassium ferrate are sequentially added to the contaminated water to be treated, and the water treatment method is completed under stirring for 10-60 min.

[0006] Further, the concentration of the carbon quantum dots solution in the contaminated water to be treated is 2-20 mg / L.

[0007] Further, the concentration of the potassium permanganate or potassium ferrate in the contaminated water to be treated is 30-100 μmol / L.

[0008] Further, the pH value of the contaminated water to be treated is 4-9.

[0009] Further, the preparation method of the carbon quantum dots solution is prepared by using existing microwave synthesis method, thermal decomposition method, hydrothermal treatment method, template path method, plasma treatment method, arc discharge treatment method, laser ablation method, electrochemical oxidation method, chemical oxidation method or ultrasonic synthesis method.

[0010] The principle of the application is mainly as follows:

[0011] The present application is proved by sub-sulfoxide probe experiment that in the ferrate / carbon quantum dots system, intermediate state Fe(IV), Fe(V) is one of active species, but is not the reason for the enhanced effect. The open circuit voltage experiment proves that the redox potential of the glassy carbon electrode coated with carbon quantum dots is higher than that of the uncoated glassy carbon electrode, and with the addition of potassium ferrate and organic pollutants (phenol) in sequence, the experiment shows that the voltage of the reaction system decreases, proving that the oxidant is consumed by the organic matter. In addition, the open circuit current experiment also proves that in the three-electrode reaction system with the glassy carbon electrode coated with carbon quantum dots as the working electrode, the addition of potassium ferrate makes the current instantaneously decrease; Subsequently, the addition of organic pollutants further significantly reduces the current, indicating that the electrons on the organic matter can be transferred to potassium ferrate through carbon quantum dots, mediating direct electron transfer. The carbon quantum dots in the present application have conductivity, and after combining carbon quantum dots and potassium ferrate, a new direct electron transfer mechanism can be generated, thereby promoting the efficiency of electron utilization and improving the oxidation efficiency of organic matter.

[0012] The present application proves by the sub-sulfur probe experiment and the ultraviolet-visible spectrum experiment that in the permanganate / carbon quantum dot system, the intermediate state manganese is not the active species for strengthening effect. The open circuit voltage experiment proves that the redox potential of the carbon quantum dot coated glassy carbon electrode is higher than that of the uncoated glassy carbon electrode, and with the addition of potassium permanganate and organic pollutants (diclofenac) in sequence, the experiment shows that the voltage of the reaction system decreases, proving that the organic matter consumes the oxidant. In addition, the open circuit current experiment also proves that in the three-electrode reaction system with the carbon quantum dot coated glassy carbon electrode as the working electrode, the addition of potassium permanganate makes the current instantaneously decrease; then the addition of organic matter further significantly decreases the current, indicating that the electrons on the organic matter can be transmitted to potassium permanganate through the carbon quantum dots, mediating the direct electron transfer. The carbon quantum dots in the present application have conductivity, and after the combination of the carbon quantum dots and potassium permanganate, a new direct electron transfer mechanism can be generated, thereby promoting the electron utilization efficiency and improving the oxidation efficiency on the organic matter.

[0013] The present application has the following beneficial effects:

[0014] 1. The present application takes phenolic substances (phenol, bisphenol A (BPA), tetrachlorophenol (4-CP), p-hydroxybenzoic acid (p-HBA), antibiotic substances (sulfamethoxazole (SMX), ibuprofen (IBP), diclofenac (DCF)) as examples, and experiments prove that the carbon quantum dot reinforced potassium ferrate (Fe(VI)+CQDs) removes organic pollutants with an increase of 10-40%, and the reaction rate is increased by 1.1-22.8 times; the carbon quantum dot reinforced potassium permanganate removes organic pollutants with an increase of 0.1-6.4 times. At the same time, the iron and manganese oxides generated after the oxidation of high-valence metal are coupled with the carbon quantum dots, which is beneficial to realize solid-liquid separation and will not cause secondary pollution. In addition, the removal efficiency changes of different water quality backgrounds (chloride ion Cl - , hydrogen phosphate ion H2PO4 - , sulfate SO4 2- , bicarbonate ion HCO3 - , calcium ion Ca 2+ , magnesium ion Mg 2+ , humic acid HA and actual water body) are explored through experiments, and it is found that the carbon quantum dot reinforced high-valence metal oxidation water treatment method has good anti-water quality change interference ability, and the carbon quantum dot reinforced potassium ferrate / potassium permanganate both increase the reaction rate, which is beneficial to the application of the method in actual engineering.

[0015] 2. The present application proves by experiments that the carbon quantum dot reinforced high-valence metal oxidation water treatment method has a wide pH application range, and the removal effect is very excellent within the pH range of 4-8.

[0016] The carbon quantum dot reinforced high-valence metal oxidation water treatment method in the application has excellent oxidation efficiency and faster reaction rate. In the potassium ferrate / carbon quantum dot system, the removal effect of organic pollutants is improved by 10-40%, and the oxidation reaction rate is improved by 1.1-22.8 times. In the potassium permanganate / carbon quantum dot system, the removal effect of organic pollutants is improved by 0.1-6.4 times.

[0017] 3, The carbon quantum dot reinforced high-valence metal oxidation water treatment method in the application has excellent oxidation efficiency and faster reaction rate. In the potassium ferrate / carbon quantum dot system, the removal effect of organic pollutants is improved by 10-40%, and the oxidation reaction rate is improved by 1.1-22.8 times. In the potassium permanganate / carbon quantum dot system, the removal effect of organic pollutants is improved by 0.1-6.4 times.

[0018] 4, The carbon quantum dot reinforced high-valence metal oxidation water treatment method in the application has excellent oxidation efficiency and faster reaction rate. In the potassium ferrate / carbon quantum dot system, the removal effect of organic pollutants is improved by 10-40%, and the oxidation reaction rate is improved by 1.1-22.8 times. In the potassium permanganate / carbon quantum dot system, the removal effect of organic pollutants is improved by 0.1-6.4 times.

[0019] 5, The carbon quantum dot reinforced high-valence metal oxidation water treatment method in the application has excellent oxidation efficiency and faster reaction rate. In the potassium ferrate / carbon quantum dot system, the removal effect of organic pollutants is improved by 10-40%, and the oxidation reaction rate is improved by 1.1-22.8 times. In the potassium permanganate / carbon quantum dot system, the removal effect of organic pollutants is improved by 0.1-6.4 times.

[0020] The application is suitable for water treatment. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The columnar chart is the test effect result of carbon quantum dots, ferrate and carbon quantum dot reinforced ferrate system for removing 7 typical pollution organic matters in examples 2, 3 and 4;

[0022] Figure 2 The columnar chart is the test effect result of carbon quantum dots, ferrate and carbon quantum dot reinforced ferrate system for removing 7 typical pollution organic matters in examples 2, 3 and 4;

[0023] Figure 3 The columnar chart is the test effect result of carbon quantum dots, ferrate and carbon quantum dot reinforced ferrate system for removing 7 typical pollution organic matters in examples 2, 3 and 4;

[0024] Figure 4 The kinetic fitting curve diagram of carbon quantum dots reinforced ferrate system for phenol oxidation in simulated polluted water body with pH value = 5, pH value = 6, and pH value = 7 in Example 5;

[0025] Figure 5 The kinetic fitting curve diagram of carbon quantum dots reinforced ferrate system for phenol oxidation in simulated polluted water body with pH value = 8, pH value = 9 in Example 5;

[0026] Figure 6 The curve diagram of carbon quantum dots reinforced ferrate system for phenol removal effect in simulated polluted water body with pH value = 5, pH value = 6, and pH value = 7 in Example 5;

[0027] Figure 7 The curve diagram of carbon quantum dots reinforced ferrate system for phenol removal effect in simulated polluted water body with pH value = 8, pH value = 9 in Example 5;

[0028] Figure 8 The curve diagram of carbon quantum dots reinforced permanganate system for DCF removal effect in simulated polluted water body with pH value = 4, pH value = 5 in Example 6;

[0029] Figure 9 The curve diagram of carbon quantum dots reinforced permanganate system for DCF removal effect in simulated polluted water body with pH value = 6, pH value = 7 in Example 6;

[0030] Figure 10 The curve diagram of carbon quantum dots reinforced permanganate system for DCF removal effect in simulated polluted water body with pH value = 8, pH value = 9 in Example 6;

[0031] Figure 11 The test result diagram of different water quality background influencing factors on the effect of carbon quantum dots reinforced ferrate system on phenol removal in Example 7;

[0032] Figure 12 The test result diagram of different water quality background influencing factors on the effect of carbon quantum dots reinforced ferrate system on phenol removal in Example 7;

[0033] Figure 13 The test result diagram of different water quality background influencing factors on the effect of carbon quantum dots reinforced ferrate system on phenol removal in Example 7;

[0034] Figure 14 The test result diagram of open circuit voltage and current change after adding potassium ferrate and phenol in Example 7;

[0035] Figure 15Figure of the test results of the influence of different water quality background factors on the removal of DCF by the carbon quantum dot reinforced permanganate system in Example 8;

[0036] Figure 16 Figure of the test results of the influence of different water quality background factors on the removal of DCF by the carbon quantum dot reinforced permanganate system in Example 8;

[0037] Figure 17 Figure of the test results of the influence of different water quality background factors on the removal of DCF by the carbon quantum dot reinforced permanganate system in Example 8;

[0038] Figure 18 Figure of the test results of the influence of different water quality background factors on the removal of DCF by the carbon quantum dot reinforced permanganate system in Example 8;

[0039] Figure 19 Figure of the test results of the open circuit voltage and current change after the addition of potassium permanganate and DCF in Example 8. DETAILED DESCRIPTION

[0040] The technical solution of the present application is not limited to the following specific embodiments, but also includes any combination of the specific embodiments.

[0041] Specific embodiment one: the water treatment method of carbon quantum dots reinforced high-valence metal oxidation in the present embodiment is realized according to the following process:

[0042] The carbon quantum dot solution and potassium permanganate or potassium ferrate are sequentially added to the contaminated water to be treated, and the water treatment method is completed after 10-60 min of stirring.

[0043] Specific embodiment two: the difference between the present embodiment and specific embodiment one is that the concentration of the carbon quantum dot solution in the contaminated water to be treated is 2-20 mg / L. The other steps and parameters are the same as those in specific embodiment one.

[0044] Specific embodiment three: the difference between the present embodiment and specific embodiment two is that the concentration of the carbon quantum dot solution in the contaminated water to be treated is 4 mg / L. The other steps and parameters are the same as those in specific embodiment two.

[0045] Specific embodiment four: the difference between the present embodiment and specific embodiment two is that the concentration of the carbon quantum dot solution in the contaminated water to be treated is 8 mg / L. The other steps and parameters are the same as those in specific embodiment two.

[0046] Specific embodiment five: the difference between this embodiment and the specific embodiment one is that the concentration of the potassium permanganate or potassium ferrate in the polluted water to be treated is 30-100 μmol / L. The other steps and parameters are the same as those in the specific embodiment one.

[0047] Specific embodiment six: the difference between this embodiment and the specific embodiment five is that the concentration of the potassium permanganate or potassium ferrate in the polluted water to be treated is 50 μmol / L. The other steps and parameters are the same as those in the specific embodiment five.

[0048] Specific embodiment seven: the difference between this embodiment and the specific embodiment one is that the pH value of the polluted water to be treated is 4-9. The other steps and parameters are the same as those in the specific embodiment one.

[0049] Specific embodiment eight: the difference between this embodiment and the specific embodiment seven is that the pH value of the polluted water to be treated is 5-8. The other steps and parameters are the same as those in the specific embodiment seven.

[0050] Specific embodiment nine: the difference between this embodiment and the specific embodiment one is that the pollutants in the polluted water to be treated are phenolic pollutants and antibiotic substances. The other steps and parameters are the same as those in the specific embodiment one.

[0051] Specific embodiment ten: the difference between this embodiment and the specific embodiment one is that the treatment time under the stirring condition is 50 min. The other steps and parameters are the same as those in the specific embodiment one.

[0052] Specific embodiment eleven: the difference between this embodiment and the specific embodiment one is that the preparation method of the carbon quantum dot solution is: using the existing microwave synthesis method, thermal decomposition method, hydrothermal treatment method, template path method, plasma treatment method, arc discharge treatment method, laser ablation method, electrochemical oxidation method, chemical oxidation method or ultrasonic synthesis method. The other steps and parameters are the same as those in the specific embodiment one.

[0053] The beneficial effects of the present application are verified by the following examples:

[0054] Example 1:

[0055] In this embodiment, the existing electrochemical oxidation method is used to prepare the carbon quantum dot solution, and the process is as follows:

[0056] I. Two graphite electrodes are inserted into the pH = 5 ultrapure water electrolyte, the electrode spacing is 7 cm, the applied voltage is 30 V, and the electrolysis is carried out for 72-96 h until the solution becomes dark yellow;

[0057] II. The above solution is filtered with a 0.22 μm polytetrafluoroethylene filter membrane to obtain a filtered solution;

[0058] III. The filtered solution was transferred to a centrifuge and centrifuged at 10,000 r / min for 40 min. The supernatant was collected to obtain the prepared carbon quantum dot solution.

[0059] Example 2

[0060] In this example, the adsorption capacity of the carbon quantum dots prepared in Example 1 for phenolic substances (phenol, bisphenol A, tetrachlorophenol, p-hydroxybenzoic acid) and antibiotic substances (sulfamethoxazole, ibuprofen, diclofenac) in simulated wastewater was investigated.

[0061] The organic pollutant mother liquor was added to a buffer solution with a pH of 7 to obtain a concentration of 6 μM, as simulated wastewater. The carbon quantum dot solution prepared in Example 1 was added to the simulated wastewater, and the reaction was carried out under stirring for 60 minutes. During the reaction, sampling was carried out every 5-10 minutes, and the concentration C of the target pollutant was determined after filtration with a 0.22 μm polytetrafluoroethylene filter. The initial concentration of each target pollutant was recorded as C0, and the change in C / C0 with the reaction time was calculated.

[0062] In this example, 7 groups of experiments were set up, and the concentration of the added carbon quantum dots was controlled to be 4 mg / L or 8 mg / L. The change in C / C0 with the reaction time for various organic pollutants is shown in Figure 1 and Figure 2 The adsorption effect of the carbon quantum dots on the organic pollutants was limited, and the removal rate was less than 10%.

[0063] Example 3

[0064] In this example, the oxidative removal effect of potassium ferrate or potassium permanganate on the above-mentioned 7 pollutants was investigated.

[0065] In this example, 14 groups of experiments were set up. The organic pollutant mother liquor was added to a buffer solution with a pH of 7 to obtain a concentration of 6 μM, as simulated wastewater. Potassium permanganate or potassium ferrate with a concentration of 30 μM was added to the simulated wastewater, and the reaction was carried out under stirring for 60 minutes. During the reaction, sampling was carried out every 5-10 minutes, and the concentration C of the target pollutant was determined after filtration with a 0.22 μm polytetrafluoroethylene filter. The initial concentration of each target pollutant was recorded as C0, and the change in C / C0 with the reaction time was calculated.

[0066] The change in C / C0 for the organic pollutants after the reaction in each group of experiments is shown in Figure 1 and Figure 2As shown, the removal rates of phenol, bisphenol A, tetrachlorophenol, p-hydroxybenzoic acid, sulfamethoxazole, ibuprofen and diclofenac by potassium ferrate were about 52%, 86%, 64%, 45%, 73%, 17% and 83%, respectively. The removal rates of potassium permanganate were about 51.9%, 88.7%, 67.2%, 12.5%, 1.8%, 26.6% and 28%, respectively. The removal of organic pollutants by potassium ferrate or potassium permanganate alone has certain limitations.

[0067] Example 4:

[0068] In this embodiment, the oxidative removal effects of the potassium ferrate / carbon quantum dot system and the potassium permanganate / carbon quantum dot system on the above-mentioned 7 kinds of pollutants are investigated.

[0069] In this embodiment, 14 groups of experiments are set. The organic pollutant mother liquor is added to a buffer solution with a pH of 7 to make its concentration 6 μM, as simulated wastewater. Carbon quantum dots are first added to the simulated wastewater at a concentration of 4 mg / L and 8 mg / L, and then potassium ferrate and potassium permanganate are added respectively to make their concentrations 30 μM, as follows:

[0070] First group of experiments: The phenol mother liquor is added to a buffer solution with a pH of 7 to make its concentration 6 μM. Then carbon quantum dots are added to make their concentration 4 mg / L. Finally, potassium ferrate solution is added to make its concentration 30 μM.

[0071] Second group of experiments: The bisphenol A mother liquor is added to a buffer solution with a pH of 7 to make its concentration 6 μM. Then carbon quantum dots are added to make their concentration 4 mg / L. Finally, potassium ferrate solution is added to make its concentration 30 μM.

[0072] Third group of experiments: The tetrachlorophenol mother liquor is added to a buffer solution with a pH of 7 to make its concentration 6 μM. Then carbon quantum dots are added to make their concentration 4 mg / L. Finally, potassium ferrate solution is added to make its concentration 30 μM.

[0073] Fourth group of experiments: The p-hydroxybenzoic acid mother liquor is added to a buffer solution with a pH of 7 to make its concentration 6 μM. Then carbon quantum dots are added to make their concentration 4 mg / L. Finally, potassium ferrate solution is added to make its concentration 30 μM.

[0074] Fifth group of experiments: The sulfamethoxazole mother liquor is added to a buffer solution with a pH of 7 to make its concentration 6 μM. Then carbon quantum dots are added to make their concentration 4 mg / L. Finally, potassium ferrate solution is added to make its concentration 30 μM.

[0075] Sixth group of experiments: Ibuprofen mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 4 mg / L. Finally, potassium ferrate solution was added, so that its concentration was 30 μΜ.

[0076] Seventh group of experiments: Diclofenac mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 4 mg / L. Finally, potassium ferrate solution was added, so that its concentration was 30 μΜ.

[0077] Eighth group of experiments: Phenol mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 8 mg / L. Finally, potassium permanganate solution was added, so that its concentration was 30 μΜ.

[0078] Ninth group of experiments: Bisphenol A mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 8 mg / L. Finally, potassium permanganate solution was added, so that its concentration was 30 μΜ.

[0079] Tenth group of experiments: Tetrachlorofen mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 8 mg / L. Finally, potassium permanganate solution was added, so that its concentration was 30 μΜ.

[0080] Eleventh group of experiments: p-Hydroxybenzoic acid mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 8 mg / L. Finally, potassium permanganate solution was added, so that its concentration was 30 μΜ.

[0081] Twelfth group of experiments: Sulfamethylisoxazole mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 8 mg / L. Finally, potassium permanganate solution was added, so that its concentration was 30 μΜ.

[0082] Thirteenth group of experiments: Ibuprofen mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 8 mg / L. Finally, potassium permanganate solution was added, so that its concentration was 30 μΜ.

[0083] Fourteenth group of experiments: Diclofenac mother liquor was added to the buffer solution with pH 7, so that its concentration was 6 μΜ. Then carbon quantum dots were added, so that its concentration was 8 mg / L. Finally, potassium permanganate solution was added, so that its concentration was 30 μΜ.

[0084] The reaction was carried out under stirring for 60 minutes. During the reaction, samples were taken every 5–10 minutes, filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane, and the concentration C of the target pollutant was determined. The initial concentration of each target pollutant was recorded as C0, and the change of C / C0 over reaction time was calculated.

[0085] The changes in the C / C ratio of organic pollutants after the reaction in each group of experiments are as follows: Figure 1 and Figure 2 As shown, the potassium ferrate / carbon quantum dot system achieved removal rates of approximately 87%, 98%, 88%, 66%, 80%, 57%, and 99% for phenol, bisphenol A, tetrachlorophenol, p-hydroxybenzoic acid, sulfamethoxazole, ibuprofen, and diclofenac, respectively. The potassium permanganate / carbon quantum dot system achieved removal rates of approximately 100%, 96%, 85.4%, 37.1%, 13.8%, 40%, and 100% for these pollutants, respectively. The potassium ferrate / carbon quantum dot system or the potassium permanganate / carbon quantum dot system significantly outperformed their respective individual systems in removing organic pollutants.

[0086] Kinetic test results of potassium ferrate / carbon quantum dot system on 7 pollutants, such as Figure 3 As shown, the apparent rate constants of potassium ferrate alone for bisphenol A, diclofenac, sulfamethoxazole, tetrachlorophenol, phenol, p-hydroxybenzoic acid, and ibuprofen are 539.87, 187.5, 276.28, 166.33, 75.65, 113.43, and 160.37 M, respectively. -1 s -1 In the carbon quantum dot-enhanced potassium ferrate system, the apparent rate constants of bisphenol A, diclofenac, sulfamethoxazole, tetrachlorophenol, phenol, p-hydroxybenzoic acid, and ibuprofen increased to 1189.40, 4270.70, 285.78, 890.32, 478.83, 300.90, and 291.43 M, respectively. -1 s -1 .

[0087] Example 5:

[0088] In this embodiment, the effect of pH change on the efficiency of phenol oxidation in the potassium ferrate / carbon quantum dot system was investigated.

[0089] In this embodiment, a total of 5 experimental groups were set up. Phenol mother liquor was added to buffer solutions with pH values ​​of 5, 6, 7, 8, and 9, respectively, so that the concentration of each solution was 6 μM, which served as simulated wastewater. 4 mg / L of carbon quantum dots were first added to the simulated wastewater, followed by potassium ferrate to bring the concentration to 30 μM.

[0090] The reaction was carried out under stirring for 60 minutes. During the reaction, sampling was carried out every 5-10 minutes, and the concentration C of phenol was determined after filtration with a 0.22 μm polytetrafluoroethylene filter. The initial concentration of phenol was denoted as C0, and the change of C / C0with the reaction time was calculated.

[0091] In each group of experiments, the simulation of the degradation kinetics of phenol by potassium ferrate or the potassium ferrate / carbon quantum dot system is shown in Figures 4-5 The change of phenol C / C0with the reaction time is shown in Figures 6-7 The potassium ferrate / carbon quantum dot system has the best effect under acidic and neutral conditions, and the effect under alkaline conditions is the second. The removal rates under pH 5 and 6 are 73% and 81% respectively, which are increased by 15% and 19% compared with the potassium ferrate system. The removal rate under pH 7 is 87%, which is increased by 36% compared with the potassium ferrate system. The removal rates under pH 8 and 9 are 46% and 30% respectively. Although the performance of the potassium ferrate / carbon quantum dot system decreases with the increase of pH, the removal effect is better than that of the potassium ferrate system under various pH conditions.

[0092] Example 6:

[0093] In this example, the influence of pH change on the oxidation efficiency of diclofenac by the potassium permanganate / carbon quantum dot system was investigated.

[0094] In this example, 6 groups of experiments were set up. The diclofenac mother liquor was added into buffer solutions with pH 4, 5, 6, 7, 8 and 9 respectively, so that the concentration was 6 μM, as simulated wastewater. 8 mg / L carbon quantum dots were first added into the simulated wastewater, and then potassium permanganate was added to make the concentration 30 μM.

[0095] The reaction was carried out under stirring for 60 minutes. During the reaction, sampling was carried out every 5-10 minutes, and the concentration C of diclofenac was determined after filtration with a 0.22 μm polytetrafluoroethylene filter. The initial concentration of diclofenac was denoted as C0, and the change of C / C0with the reaction time was calculated.

[0096] In each group of experiments, the change of diclofenac C / C0with the reaction time is shown in Figures 8-10 The potassium permanganate / carbon quantum dot system has the best effect under acidic and neutral conditions, and the effect under alkaline conditions is the second. The removal rates under pH 5 and 6 are 73% and 81% respectively, which are increased by 15% and 19% compared with the potassium ferrate system. The removal rate under pH 7 is 87%, which is increased by 36% compared with the potassium ferrate system. The removal rates under pH 8 and 9 are 46% and 30% respectively. Although the performance of the potassium ferrate / carbon quantum dot system decreases with the increase of pH, the removal effect is better than that of the potassium ferrate system under various pH conditions.

[0097] Example 7:

[0098] In this example, the influence of water quality background ion change and actual water body on the oxidation efficiency of phenol by the potassium ferrate / carbon quantum dot system was investigated.

[0099] In this example, 7 groups of experiments were set up, as follows:

[0100] First group of experiments: Phenol stock solution was added to a buffer solution with pH 7 so that its concentration was 6 μΜ, then chloride ions were added so that their concentrations were 1 mM, 3 mM and 5 mM respectively, as simulated wastewater. 4 mg / L carbon quantum dots were added to the simulated wastewater first, and then potassium ferrate was added so that its concentration was 30 μΜ.

[0101] Second group of experiments: Phenol stock solution was added to a buffer solution with pH 7 so that its concentration was 6 μΜ, then hydrogen phosphate ions were added so that their concentrations were 1 mM, 3 mM and 5 mM respectively, as simulated wastewater. 4 mg / L carbon quantum dots were added to the simulated wastewater first, and then potassium ferrate was added so that its concentration was 30 μΜ.

[0102] Third group of experiments: Phenol stock solution was added to a buffer solution with pH 7 so that its concentration was 6 μΜ, then bicarbonate ions were added so that their concentrations were 1 mM, 3 mM and 5 mM respectively, as simulated wastewater. 4 mg / L carbon quantum dots were added to the simulated wastewater first, and then potassium ferrate was added so that its concentration was 30 μΜ.

[0103] Fourth group of experiments: Phenol stock solution was added to a buffer solution with pH 7 so that its concentration was 6 μΜ, then calcium ions were added so that their concentrations were 1 mM, 3 mM and 5 mM respectively, as simulated wastewater. 4 mg / L carbon quantum dots were added to the simulated wastewater first, and then potassium ferrate was added so that its concentration was 30 μΜ.

[0104] Fifth group of experiments: Phenol stock solution was added to a buffer solution with pH 7 so that its concentration was 6 μΜ, then magnesium ions were added so that their concentrations were 1 mM, 3 mM and 5 mM respectively, as simulated wastewater. 4 mg / L carbon quantum dots were added to the simulated wastewater first, and then potassium ferrate was added so that its concentration was 30 μΜ.

[0105] Sixth group of experiments: Phenol stock solution was added to a buffer solution with pH 7 so that its concentration was 6 μΜ, then humic acid was added so that its concentrations were 2 mg / L, 5 mg / L and 10 mg / L respectively, as simulated wastewater. 4 mg / L carbon quantum dots were added to the simulated wastewater first, and then potassium ferrate was added so that its concentration was 30 μΜ.

[0106] Seventh group of experiments: Phenol stock solution was added to a conical flask containing 100 mL of river water so that its concentration was 6 μΜ, as actual wastewater. 4 mg / L carbon quantum dots were added to the actual wastewater first, and then potassium ferrate was added so that its concentration was 30 μΜ.

[0107] The reaction was carried out under stirring for 60 minutes. During the reaction, samples were taken every 5-10 minutes, filtered with 0.22 μm polytetrafluoroethylene filter membrane, and the concentration C of phenol was determined. The initial concentration of phenol was recorded as C0, and the change of C / C0 with reaction time was calculated.

[0108] As shown in Fig. 2, the change of C / C0 of phenol with reaction time in each group of experiments was as follows: the potassium ferrate / carbon quantum dot system was not affected by chloride ions, and the removal rate was about 87%. Phosphate had a certain inhibitory effect on the potassium ferrate / carbon quantum dot system. With the increase of phosphate concentration from 1 mM to 5 mM, the removal efficiency of phenol decreased from 50% to 40%, but the removal effect of phenol was still close to that of the potassium ferrate system alone. Similarly, bicarbonate had a certain inhibitory effect on the potassium ferrate / carbon quantum dot system. With the increase of bicarbonate concentration from 1 mM to 3 mM, the removal efficiency of phenol decreased from 82% to 64% and 44%. In the case of low bicarbonate concentration, the removal effect of phenol by the potassium ferrate / carbon quantum dot system was higher than that by the potassium ferrate system alone, and the removal rate was 54%. Figures 11-13 As shown in Fig. 2, the change of C / C0 of phenol with reaction time in each group of experiments was as follows: the potassium ferrate / carbon quantum dot system was not affected by chloride ions, and the removal rate was about 87%. Phosphate had a certain inhibitory effect on the potassium ferrate / carbon quantum dot system. With the increase of phosphate concentration from 1 mM to 5 mM, the removal efficiency of phenol decreased from 50% to 40%, but the removal effect of phenol was still close to that of the potassium ferrate system alone. Similarly, bicarbonate had a certain inhibitory effect on the potassium ferrate / carbon quantum dot system. With the increase of bicarbonate concentration from 1 mM to 3 mM, the removal efficiency of phenol decreased from 82% to 64% and 44%. In the case of low bicarbonate concentration, the removal effect of phenol by the potassium ferrate / carbon quantum dot system was higher than that by the potassium ferrate system alone, and the removal rate was 54%.

[0109] As shown in Fig. 2, the change of C / C0 of phenol with reaction time in each group of experiments was as follows: the potassium ferrate / carbon quantum dot system was not affected by chloride ions, and the removal rate was about 87%. Phosphate had a certain inhibitory effect on the potassium ferrate / carbon quantum dot system. With the increase of phosphate concentration from 1 mM to 5 mM, the removal efficiency of phenol decreased from 50% to 40%, but the removal effect of phenol was still close to that of the potassium ferrate system alone. Similarly, bicarbonate had a certain inhibitory effect on the potassium ferrate / carbon quantum dot system. With the increase of bicarbonate concentration from 1 mM to 3 mM, the removal efficiency of phenol decreased from 82% to 64% and 44%. In the case of low bicarbonate concentration, the removal effect of phenol by the potassium ferrate / carbon quantum dot system was higher than that by the potassium ferrate system alone, and the removal rate was 54%.

[0110] Figure 14 As shown in Fig. 2, the change of C / C0 of phenol with reaction time in each group of experiments was as follows: the potassium ferrate / carbon quantum dot system was not affected by chloride ions, and the removal rate was about 87%. Phosphate had a certain inhibitory effect on the potassium ferrate / carbon quantum dot system. With the increase of phosphate concentration from 1 mM to 5 mM, the removal efficiency of phenol decreased from 50% to 40%, but the removal effect of phenol was still close to that of the potassium ferrate system alone. Similarly, bicarbonate had a certain inhibitory effect on the potassium ferrate / carbon quantum dot system. With the increase of bicarbonate concentration from 1 mM to 3 mM, the removal efficiency of phenol decreased from 82% to 64% and 44%. In the case of low bicarbonate concentration, the removal effect of phenol by the potassium ferrate / carbon quantum dot system was higher than that by the potassium ferrate system alone, and the removal rate was 54%.

[0111] Example 8:

[0112] ​In this embodiment, the effect of water quality background ion changes and actual water body on the efficiency of potassium permanganate / carbon quantum dot system in oxidizing diclofenac is investigated.

[0113] In this embodiment, 8 groups of experiments are set, as follows:

[0114] The first group of experiments: the diclofenac mother liquor is added to a buffer solution with pH of 7, so that the concentration is 6 μM, then chloride ions are added, with concentrations of 1 mM, 3 mM and 5 mM, as simulated wastewater. 8 mg / L of carbon quantum dots are added to the simulated wastewater, and then potassium permanganate is added to make the concentration 30 μM.

[0115] The second group of experiments: the diclofenac mother liquor is added to a buffer solution with pH of 7, so that the concentration is 6 μM, then sulfate ions are added, with concentrations of 1 mM, 3 mM and 5 mM, as simulated wastewater. 8 mg / L of carbon quantum dots are added to the simulated wastewater, and then potassium permanganate is added to make the concentration 30 μM.

[0116] The third group of experiments: the diclofenac mother liquor is added to a buffer solution with pH of 7, so that the concentration is 6 μM, then bicarbonate ions are added, with concentrations of 1 mM, 3 mM and 5 mM, as simulated wastewater. 8 mg / L of carbon quantum dots are added to the simulated wastewater, and then potassium permanganate is added to make the concentration 30 μM.

[0117] The fourth group of experiments: the diclofenac mother liquor is added to a buffer solution with pH of 7, so that the concentration is 6 μM, then hydrogen phosphate ions are added, with concentrations of 1 mM, 3 mM and 5 mM, as simulated wastewater. 8 mg / L of carbon quantum dots are added to the simulated wastewater, and then potassium permanganate is added to make the concentration 30 μM.

[0118] The fifth group of experiments: the diclofenac mother liquor is added to a buffer solution with pH of 7, so that the concentration is 6 μM, then calcium ions are added, with concentrations of 1 mM, 3 mM and 5 mM, as simulated wastewater. 8 mg / L of carbon quantum dots are added to the simulated wastewater, and then potassium permanganate is added to make the concentration 30 μM.

[0119] The sixth group of experiments: the diclofenac mother liquor is added to a buffer solution with pH of 7, so that the concentration is 6 μM, then magnesium ions are added, with concentrations of 1 mM, 3 mM and 5 mM, as simulated wastewater. 8 mg / L of carbon quantum dots are added to the simulated wastewater, and then potassium permanganate is added to make the concentration 30 μM.

[0120] Experiment 7: Diclofenac stock solution was added to a buffer solution with a pH of 7 to achieve a concentration of 6 μM. Humic acid was then added to achieve concentrations of 2 mg / L, 5 mg / L, and 10 mg / L, respectively, to create simulated wastewater. 8 mg / L of carbon quantum dots was added to the simulated wastewater, followed by potassium permanganate to achieve a concentration of 30 μM.

[0121] Experiment 8: Diclofenac stock solution was added to an Erlenmeyer flask containing 100 mL of river water to achieve a concentration of 6 μM, which was then used as the actual wastewater. 8 mg / L of carbon quantum dots were added to the actual wastewater, followed by potassium permanganate to achieve a concentration of 30 μM.

[0122] The reaction was carried out under stirring for 60 minutes. During the reaction, samples were taken every 5–10 minutes, filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane, and the concentration C of diclofenac was determined. The initial concentration of diclofenac was recorded as C0, and the change in C / C0 over reaction time was calculated.

[0123] The changes in C / C ratio of diclofenac with reaction time in each group of experiments are as follows: Figures 15-18 As shown, the potassium permanganate / carbon quantum dot system is largely unaffected by chloride ions, sulfate ions, bicarbonate ions, and humic acid. Phosphate ions have a significant promoting effect on the potassium permanganate / carbon quantum dot system; after 10 minutes of reaction, as the phosphate concentration increases from 1 mM to 5 mM, the removal rate of diclofenac increases from 55% to 100%. Calcium ions have a certain inhibitory effect on the potassium permanganate / carbon quantum dot system; as the calcium ion concentration increases from 1 mM to 5 mM, the removal rate of diclofenac decreases from 86% to 80%. Magnesium ions have a certain promoting effect on the potassium permanganate / carbon quantum dot system; 1 mM magnesium ions enable the potassium permanganate / carbon quantum dot system to remove 100% of diclofenac within 20 minutes. In actual water bodies, the potassium permanganate / carbon quantum dot system also showed significantly better removal efficiency for diclofenac than the potassium permanganate system. Potassium permanganate alone could only remove 27% of diclofenac, while the potassium permanganate / carbon quantum dot system could remove 74% of diclofenac, representing a 47% improvement in performance.

[0124] The test results of open-circuit voltage and current changes after adding potassium permanganate and DCF are as follows: Figure 19 As shown, the open-circuit voltage of the carbon quantum dot electrode was +1.00V, which decreased to +0.94V with the addition of potassium permanganate. With further addition of DCF, the open-circuit voltage decreased to +0.78V, demonstrating that electrons transferred from DCF to the potassium permanganate / carbon quantum dot system. Chronoamperometry results showed that the current also decreased significantly with the addition of potassium permanganate and DCF, decreasing from -0.37μA to -0.43μA, further proving that electrons were transferred from DCF to potassium permanganate in the system, and that the carbon quantum dots played a role in electron transfer.

Claims

1. A water treatment method of carbon quantum dots reinforced high valence metal oxidation, characterized by It realizes the following process: The carbon quantum dot solution and potassium permanganate or potassium ferrate are sequentially added into the contaminated water to be treated, and the water treatment method is completed after 10-60 min of stirring treatment; The concentration of the carbon quantum dot solution in the contaminated water to be treated is 2-20 mg / L; The concentration of the potassium permanganate or potassium ferrate in the contaminated water to be treated is 30-100 μmol / L; The pH value of the contaminated water to be treated is 4-9; The pollutants in the contaminated water to be treated are phenolic pollutants and antibiotic substances; The preparation method of the carbon quantum dot solution is as follows: I. Two graphite electrodes are inserted into an ultrapure water electrolyte with pH=5, the electrode spacing is 7 cm, the applied voltage is 30 V, and electrolysis is performed for 72-96 h until the solution turns dark yellow; II. The above solution is filtered with a 0.22 μm polytetrafluoroethylene filter membrane to obtain a filtered solution; III. The filtered solution is transferred to a centrifuge, centrifuged at 10000 r / min for 40 min, and the supernatant is taken as the prepared carbon quantum dot solution.

2. The water treatment method for carbon quantum dot-enhanced high-valence metal oxidation according to claim 1, characterized in that... The concentration of the carbon quantum dot solution in the contaminated water to be treated is 4 mg / L.

3. The water treatment method for carbon quantum dot-enhanced high-valence metal oxidation according to claim 1, characterized in that... The concentration of the carbon quantum dot solution in the contaminated water to be treated is 8 mg / L.

4. The water treatment method for carbon quantum dot-enhanced high-valence metal oxidation according to claim 1, characterized in that... The concentration of the potassium permanganate or potassium ferrate in the contaminated water to be treated is 50 μmol / L.

5. The water treatment method for carbon quantum dot-enhanced high-valence metal oxidation according to claim 1, characterized in that... The stirring treatment time is 50 min.

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