A method for efficiently treating refractory organic pollutants by three-dimensional electrically activated persulfate

Abstract

The application discloses a method for treating refractory organic pollutants by three-dimensional electrically activated persulfate, and belongs to the field of water treatment.The method is prepared by a low-temperature hydrothermal reduction method to prepare nano-silver particles / reduced graphene oxide hydrogel, an IrO2 electrode is used as an anode, a stainless steel plate is used as a cathode, the nano-silver particles / reduced graphene oxide hydrogel is filled as a particle electrode, a three-dimensional electrolysis system is constructed, the efficiency of activated persulfate is improved through the particle electrode, and active substances such as generated sulfate radicals and hydroxyl radicals are used to realize efficient removal of refractory organic pollutants in wastewater.The application provides a preparation method of the nano-silver particles / reduced graphene oxide hydrogel, and is used for improving the activation efficiency of three-dimensional electrically activated persulfate, and realizes efficient removal of refractory organic pollutants.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wastewater treatment, and particularly relates to a method for treating refractory organic pollutants by in-situ generation of strong oxidizing active substances using a nano-silver particle / reduced graphene oxide hydrogel particle electrode and a three-dimensional electro-activated persulfate method. BACKGROUND

[0002] The persulfate advanced oxidation technology utilizes sulfate radicals (SO4 ·– ) with high oxidation-reduction potential, which can achieve efficient degradation of most organic pollutants under ideal conditions, and is widely used in organic wastewater treatment, sludge treatment and soil remediation. The key to this technology is the efficient activation of persulfate. Electro-activated persulfate technology has mild reaction conditions, simple reaction system, high energy efficiency and strong controllability, and is an efficient, environmentally friendly and promising activation method, which has attracted much attention from researchers in recent years.

[0003] Currently, the research on electro-activated persulfate mainly focuses on the traditional two-dimensional electrochemical system based on metal, metal oxide and carbon material electrodes. However, the problems such as ion leaching of metal electrodes, low catalytic activity of metal oxide electrodes, high price of boron-doped diamond electrodes, and poor stability of other carbon material electrodes also limit the efficient application of two-dimensional electro-activation process. The three-dimensional electrochemical system utilizes particle microelectrodes to increase the electrode surface area and the number of active centers, which can be applied to the activation of persulfate. The particle electrode electro-adsorption can enhance the aggregation of persulfate on its surface, improve the electron transfer rate, and promote the activation efficiency of persulfate. The core of three-dimensional electro-activated persulfate process is to develop new particle electrodes with high catalytic activity and high stability. The existing particle electrodes that have achieved engineering application in wastewater three-dimensional electrolysis process are mainly activated carbon particles and iron-carbon particles, but their catalytic activity needs to be improved.

[0004] As a two-dimensional carbon nanomaterial, graphene has excellent electrical conductivity and large specific surface area, which is beneficial to strengthen the electro-adsorption process of active substances in three-dimensional electrochemical system, effectively shorten the transmission distance of electrons and ions, and improve the mass transfer performance, making it an excellent choice for particle electrodes. However, the effect of graphene alone in activating persulfate is limited, and heteroatom doping or transition metal loading is an effective means to improve the catalytic activity of graphene. Transition metals themselves are a class of efficient persulfate activators, and by loading transition metals on graphene, the catalytic active sites can be increased to achieve the purpose of improving the activation efficiency of persulfate.

[0005] To prepare a stable supported particle electrode, light, porous and excellent reduced graphene oxide hydrogel can provide a way. Reduced graphene oxide hydrogel has a large specific surface area and a large number of controllable pore channel structures, which can provide sufficient transmission channels for the diffusion of pollutants, and is an excellent carrier for doped metals. In addition, reduced graphene oxide also has excellent electron transport performance, and has the layered structure of graphene oxide, which is beneficial to increase the contact area with pollutants and reduce the agglomeration of the loaded active substances, and the electron transfer and redox effect caused by the surface oxygen-containing functional groups and metal particles can further promote the generation of SO4 ·– SUMMARY

[0006] The purpose of the present application is to solve the above problems in the prior art, provide a kind of nano silver particle / reduced graphene oxide particle electrode and a kind of three-dimensional electrically activated persulfate efficient treatment of refractory organic pollutants method, using the method utilizes nano silver particle / reduced graphene oxide particle electrode three-dimensional electrically activated persulfate, can realize the efficient removal of refractory organic pollutants in wastewater.

[0007] The above-mentioned purpose of the present application can be realized by the following technical solutions:

[0008] A nano silver particle / reduced graphene oxide hydrogel particle electrode comprises nano silver particles and reduced graphene oxide layers, the nano silver particles are uniformly loaded between the reduced graphene oxide layers to form a nano silver particle / reduced graphene oxide hydrogel structure, and further, the water content of the nano silver particle / reduced graphene oxide hydrogel is 70-90wt%, specifically, the mass of the hydrogel is about 0.6g, and the water content is about 87wt%.

[0009] Further, the nano silver particle / reduced graphene oxide hydrogel particle electrode is prepared by a low-temperature hydrothermal method, specifically, a graphene oxide aqueous solution, an AgNO3 solution and a NaHSO3 solution are used as precursors, mixed uniformly in a sealed reaction bottle, and reacted in a water bath at a proper temperature until the hydrogel with a certain macroscopic size is gradually self-assembled.

[0010] Preferably, the concentration of the used graphene oxide is 0.6mg / L, the concentration of AgNO3 is 0.3mmol / L, the concentration of NaHSO3 is 0.5mg / mL, the water bath heating temperature is 80℃, and the reaction time is 15h.

[0011] The present application also provides a kind of three-dimensional electrically activated persulfate efficient treatment of refractory organic pollutants method, specifically comprising the following steps:

[0012] ​S1, in a single-chamber reactor, a certain amount of wastewater to be treated and persulfate are added, an IrO2 electrode and a stainless steel plate electrode with the same area are loaded respectively, and nano-silver particles / reduced graphene oxide hydrogel is filled to construct a three-dimensional electro-activation system;

[0013] S2, with the IrO2 electrode as the anode and the stainless steel plate as the cathode, the power supply is connected, and the changes of current, voltage and pollutant concentration during the reaction process are monitored;

[0014] S3, after the reaction is completed, the particles in the reactor are recovered, and the treated wastewater is discharged.

[0015] As a preferred, the persulfate in step S1 is usually peroxodisulfate, such as Na2S2O8.

[0016] As a preferred, in step S2, if the conductivity of the wastewater is too low, a supporting electrolyte (such as Na2SO4) can be added to increase the solution conductivity and reduce the reaction voltage.

[0017] As a preferred, the solution in step S2 is acidic, which is beneficial to improve the electro-activation efficiency, and when the water body contains chloride (such as NaCl), the pollutant removal rate can be greatly improved.

[0018] As a preferred, in step S2, the current density is controlled at 20-40 mA / cm 2 after the power supply is turned on, and the voltage does not exceed 15V, preferably, the current density is 30 mA / cm 2 .

[0019] As a preferred, the treated wastewater in step S3 can achieve complete removal of refractory organic pollutants.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] (1) The present application provides a method for treating refractory organic pollutants by three-dimensional electro-activation of persulfate, which uses an IrO2 electrode as the anode, a stainless steel plate as the cathode, and nano-silver particles / reduced graphene oxide hydrogel as the particle electrode to form a three-dimensional electrode reaction system. This reaction system can efficiently treat refractory organic pollutants, and the use of nano-silver particles / reduced graphene oxide hydrogel as the particle electrode improves the activity of the reaction system.

[0022] (2) The nano-silver particle / reduced graphene oxide hydrogel provided by the application is obtained by a low-temperature hydrothermal method, the method does not need high temperature and high pressure, and the low-temperature hydrothermal method is simple to operate and easy to control, and the prepared nano-silver particle / reduced graphene oxide hydrogel is uniformly dispersed and has high stability; the nano-silver particles are distributed on the surface layer of the reduced graphene oxide or inserted into the gullies formed by the reduced graphene oxide, compared with the two-dimensional electrically activated persulfate, the nano-silver particle / reduced graphene oxide hydrogel particle electrode added in the application constructs a three-dimensional electrically activated persulfate system, the activated persulfate capacity is stronger, and the pollutant removal efficiency is higher; compared with the iron-carbon particle electrode, the activity is higher, and the pollutant removal efficiency is higher. The research of the application finds that the nano-silver particle / reduced graphene oxide hydrogel particle has good stability and can be reused.

[0023] (3) The nano-silver particles are loaded between the reduced graphene oxide sheet layers in the application, the activation efficiency is synergistically utilized, the catalytic active sites are increased, and the persulfate activation efficiency is improved.

[0024] (4) The application finds through research and comparison that adding sodium chloride in the wastewater treatment system by the method of the application can improve the reaction activity of the system, accelerate the degradation and decomposition of the refractory pollutants in the wastewater, and improve the reaction activity compared with other electrolytes. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The nano-silver particle / reduced graphene oxide hydrogel morphology and structure characterization (a: SEM diagram; b: XRD diagram; c: XPS diagram; d: deconvolution C1s peak; e: deconvolution O1s peak; f: Ag3d scanning peak);

[0026] Figure 2 The efficiency of electrically activated persulfate degradation of acid orange 74 wastewater;

[0027] Figure 3 The stability test results of three-dimensional electrically activated persulfate degradation of acid orange 74 wastewater;

[0028] Figure 4 The influence of water body background components on three-dimensional electrically activated persulfate degradation of acid orange 74;

[0029] Figure 5 The schematic diagram of three-dimensional electrically activated persulfate degradation of wastewater of the application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the application patent more clear and understandable, the following will combine the drawings of the application with the specific embodiments of the application. Figures 1-5The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and is not intended to limit the invention.

[0032] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. A composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0033] The phrase "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for conventional impurities associated with them. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0034] When a dosage, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4,” “1 to 3,” “1 to 2,” “1 to 2 and 4 to 5,” “1 to 3 and 5,” etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0035] In some instances, approximate terms may correspond to the instrument precision of the measured values. In this specification and claims, scope definitions may be combined and / or interchanged. Unless otherwise stated, these scopes include all subscopes contained therein.

[0036] The indefinite articles "a" and "an," as used herein in the specification, unless clearly indicated otherwise, together with the words "comprising," "containing" or "including" or with the like, do not exclude other elements or steps. The indefinite articles "a" and "an," as used herein in the specification, denote one or more, unless otherwise clearly indicated in the context.

[0037] The terms "one embodiment", "some embodiments", "an example", "some examples" or "one specific embodiment" or "some specific embodiments" as used herein describe specific features, structures, materials or characteristics included in at least one embodiment of the application. The terminology used herein should not be interpreted as a limitation on the applicability of the various embodiments described, since various changes and modifications can be made to the preferred embodiments. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the application. It is therefore contemplated to be within the scope of the present application that

[0038] The raw materials and equipment used in the present application are commercially available or commonly used in the art, unless otherwise specified. The methods used in the examples are conventional methods in the art, unless otherwise specified.

[0039] In some embodiments, the present application provides a method for efficiently treating refractory organic pollutants by three-dimensional electro-activated persulfate, which uses IrO2 electrode as anode, stainless steel plate as cathode, and nano-silver particle / reduced graphene oxide hydrogel as particle electrode to form a three-dimensional electrode reaction system, and then adds wastewater to be treated and persulfate and processes after connecting the power supply.

[0040] In some embodiments, the nano-silver particle / reduced graphene oxide hydrogel has a mass of about 0.6 g and a water content of about 87 wt%, and the nano-silver particles are uniformly loaded between the layers of reduced graphene oxide.

[0041] In some embodiments, the nano-silver particle / reduced graphene oxide hydrogel particle electrode is prepared by a low-temperature hydrothermal reduction method, which specifically uses graphene oxide aqueous solution, AgNO3 solution and NaHSO3 solution as reaction precursors, uniformly mixes them in a sealed reaction bottle, and keeps the reaction at 70-90°C in a water bath for 10-20 h until the hydrogel is gradually self-assembled. Further, the concentration of the graphene oxide aqueous solution is 0.6 mg / L, the concentration of the AgNO3 solution is 0.3 mmol / L, and the concentration of the NaHSO3 solution is 0.3 mg / mL. Preferably, the water bath heating temperature is 80°C, and the reaction time is 15 h.

[0042] In some embodiments, the method specifically includes the following steps:

[0043] S1, in a single-chamber reactor, a certain amount of wastewater to be treated and persulfate are added, an IrO2 electrode and a stainless steel plate electrode with the same area are loaded respectively, and nano-silver particles / reduced graphene oxide hydrogel is filled to construct a three-dimensional electro-activation system;

[0044] S2, with the IrO2 electrode as the anode and the stainless steel plate as the cathode, the power supply is connected, and the changes of current, voltage and pollutant concentration during the reaction process are monitored;

[0045] S3, after the reaction is completed, the particle electrode in the reactor is recovered, and the treated wastewater is discharged.

[0046] The synthesis method of the nano-silver particle / reduced graphene oxide hydrogel is as follows: in a sealed reactor, a certain proportion of graphene oxide aqueous solution, AgNO3 solution and NaHSO3 solution are added, a low-temperature hydrothermal reduction method is used to prepare the nano-silver particle / reduced graphene oxide hydrogel, and after the reaction is completed, the hydrogel is washed clean with a large amount of deionized water for use; the water bath is kept at 70-90 DEG C for 10-20 h, and the hydrogel is gradually self-assembled. Further, the concentration of the graphene oxide aqueous solution is 0.6 mg / L, the concentration of the AgNO3 solution is 0.3 mmol / L, and the concentration of the NaHSO3 solution is 0.3 mg / mL, preferably, the water bath heating temperature is 80 DEG C, and the reaction time is 15 h.

[0047] Further, the persulfate in step S1 is peroxodisulfate, such as sodium persulfate. Further, sodium sulfate 、 sodium chloride, sodium phosphate, sodium carbonate and the like. Further, the wastewater is acid orange 74.

[0048] Further, in step S2, the current density is controlled to be 20-40 mA / cm 2 after the power supply is turned on, and the voltage is not more than 15 V, preferably, the current density is 30 mA / cm 2 .

[0049] The following is further illustrated in combination with specific examples.

[0050] The embodiment of the application investigates the method for preparing the nano-silver particle / reduced graphene oxide hydrogel by a low-temperature hydrothermal method, and the degradation efficiency of the three-dimensional electro-activated persulfate in degrading acid orange 74, a typical refractory organic wastewater.

[0051] Example 1

[0052] A method for preparing a nano-silver particle / reduced graphene oxide hydrogel by a low-temperature hydrothermal method, specifically comprising the following steps:

[0053] S1, 13 mL of mixed solution of graphene oxide aqueous solution with a concentration of 0.6 mg / L, 0.3 mmol / L of AgNO3 solution and 0.3 mg / mL of NaHSO3 solution is added into a sealed reaction bottle;

[0054] S2, after the mixed solution is shaken well, it is placed in a water bath kettle at 80 DEG C, and reacts for 15 h until it is gradually self-assembled into a hydrogel with a certain macroscopic size;

[0055] S3, after the reaction is completed, the hydrogel is taken out and repeatedly washed with a large amount of deionized water.

[0056] Example 1 mainly characterizes the morphology, crystal structure and element composition of the nano-silver particle / reduced graphene oxide hydrogel, as shown in the following table. Figure 1 As can be seen from the SEM graph Figure 1 a), the prepared nano-silver particle / reduced graphene oxide hydrogel has a porous three-dimensional structure, and the nano-silver particles can be clearly observed to be distributed on the surface of the reduced graphene oxide or inserted into the gullies formed by the reduced graphene oxide, which confirms that the nano-silver particles are successfully loaded on the surface of the reduced graphene oxide sheet layer and have a relatively ideal microstructure. Figure 1 In the XRD spectrum of b, the crystal diffraction peaks appear at 2θ of 38.1°, 44.3°, 64.5° and 77.4°, respectively, corresponding to the (111), (200), (220) and (311) crystal planes of elemental silver, which proves the existence of nano-silver particles in the hydrogel. Figure 1 The XPS spectrum of c can further confirm the existence of nano-silver particles. In addition, Figure 1 d is the deconvoluted C1s peak, the C1s spectrum is mainly C-C / C-H and C-O, and the proportion of C=O and COOR is low, which indicates that the rGO has a high reduction degree, and the more oxygen-containing groups on the surface will be beneficial to the electro-activated persulfate process; Figure 1 e is the deconvoluted O1s peak, and the O1s spectrum also confirms that it is mainly O-H; Figure 1 f shows two binding energy peaks at 368.2 eV (Ag3d 5 / 2 ) and 374.2 eV (Ag3d 3 / 2 ), and the distance between the two peaks is about 6 eV, which is the characteristic signal of Ag 0 . In summary, a relatively ideal nano-silver particle / reduced graphene oxide hydrogel can be obtained by low-temperature hydrothermal reduction method.

[0057] Example 2

[0058] A method for degrading acid orange 74 by three-dimensional electro-activated persulfate, specifically comprising the following steps:

[0059] S1, 200 mL of acid orange 74 wastewater with a concentration of 100 mg / L was added to the electrochemical reactor, and 5 mmol / L sodium persulfate and 2.5 g / L Na2SO4 were added as supporting electrolyte;

[0060] S2, an IrO2 electrode was loaded as an anode, an equal-area stainless steel plate was used as a cathode, and a nano-silver particle / reduced graphene oxide hydrogel particle electrode was filled to construct a three-dimensional electro-activated persulfate system;

[0061] S3, the power was turned on, the current was set to 60 mA / cm 2 , and the reaction process was accompanied by stirring at a rate of 600 rmp; the changes in current, wastewater color, and acid orange 74 concentration during the reaction process were monitored;

[0062] S4, after 3 h of treatment, the power switch was turned off, the hydrogel particles were removed, and the treated wastewater was discharged.

[0063] Example 3

[0064] The only difference from Example 2 is that the system is not filled with nano-silver particle / reduced graphene oxide hydrogel.

[0065] Example 4

[0066] The only difference from Example 2 is that the filled particle electrode is replaced by iron / reduced graphene oxide hydrogel.

[0067] Examples 2-4 mainly investigate the efficiency difference of three-dimensional electro-activated persulfate system and two-dimensional electro-activated persulfate system in degrading acid orange 74 wastewater, and the results are shown in Figure 2 After 3 h of degradation, the removal rates of acid orange 74 in the nano-silver particle / reduced graphene oxide hydrogel particle electrode three-dimensional electro-activated system, the iron / reduced graphene oxide hydrogel particle electrode three-dimensional electro-activated system, and the two-dimensional electro-activated system are 94.0%, 85.3%, and 74.8%, respectively. It can be seen that compared to two-dimensional electro-activation, the removal efficiency of pollutants in the three-dimensional electro-activated system is significantly improved, and the nano-silver particle / reduced graphene oxide hydrogel particle electrode shows more excellent degradation effect. As shown in the Figure 2 illustration, whether it is a three-dimensional or two-dimensional system, the degradation of acid orange 74 conforms to the pseudo-first-order kinetic model, and the degradation rate of the nano-silver particle / reduced graphene oxide hydrogel particle electrode three-dimensional electro-activated system is 1.48 and 2.06 times that of the iron / reduced graphene oxide hydrogel particle electrode three-dimensional electro-activated system and the two-dimensional electro-activated system, respectively. Therefore, by adding the nano-silver particle / reduced graphene oxide hydrogel particle electrode, the efficiency of electro-activated persulfate can be enhanced.

[0068] Example 5

[0069] A method for degrading acid orange 74 by three-dimensional electro-activated persulfate, specifically comprising the following steps:

[0070] S1, 200 mL of acid orange 74 wastewater with a concentration of 50 mg / L is added to the anode chamber of the electrochemical reactor, and an equal volume of deionized water is added to the cathode chamber;

[0071] S2, 3 mmol / L of sodium persulfate is added to the anode chamber, and 0.5 mol / L of Na2SO4 is added as a supporting electrolyte; an equal concentration of Na2SO4 supporting electrolyte is added to the cathode chamber.

[0072] S3, a nano-silver modified carbon paper electrode with a deposition time of 40 s is installed in the anode chamber, and a stainless steel electrode with the same area is installed in the cathode chamber, the power supply of the electrochemical reactor is turned on, and the current is set to 60 mA / cm 2 , the anode and cathode chambers are stirred at a rate of 600 rmp during the reaction process; the current and the color change of the wastewater are monitored;

[0073] S4, after 2 h of treatment, the power switch is turned off, the drainage system of the anode chamber of the reactor is opened, and the treated wastewater is discharged.

[0074] Example 6

[0075] The difference from Example 5 is only that the filled nano-silver particle / reduced graphene oxide hydrogel is used for the second time.

[0076] Example 7

[0077] The difference from Example 5 is only that the filled nano-silver particle / reduced graphene oxide hydrogel is used for the third time.

[0078] Example 8

[0079] The difference from Example 5 is only that the filled nano-silver particle / reduced graphene oxide hydrogel is used for the fourth time.

[0080] Example 9

[0081] The difference from Example 5 is only that the filled nano-silver particle / reduced graphene oxide hydrogel is used for the fifth time.

[0082] Examples 5-9 mainly investigate the stability of the nano-silver particle / reduced graphene oxide hydrogel particle electrode, specifically as Figure 3The removal rates of acid orange 74 were 94.0%, 92.7%, 89.8%, 82.9% and 76.8% respectively after 3h degradation in five experiments. It can be seen that the activation performance of the silver nanoparticle / reduced graphene oxide hydrogel particle electrode does not decrease obviously in the first three experiments, but the removal rate of acid orange 74 decreases obviously from the fourth experiment. From the results of the stability experiment, the silver nanoparticle / reduced graphene oxide hydrogel has good stability and can meet the requirements of repeated use. The silver content in the treated solution was determined by ICP-MS, which was 6.5, 8.7, 8.8, 9.1 and 3.8mg / L respectively. It can be seen that the activity decrease is mainly caused by the dissolution of silver nanoparticles.

[0083] Example 10

[0084] A method for degrading acid orange 74 by three-dimensional electro-activated persulfate, specifically comprising the following steps:

[0085] S1, 200mL of acid orange 74 wastewater with a concentration of 50mg / L is added to the anode chamber of the electrochemical reactor, and an equal volume of deionized water is added to the cathode chamber;

[0086] S2, 3mmol / L of sodium persulfate is added to the anode chamber, and 0.5mol / L of Na2SO4 is added as a supporting electrolyte; an equal concentration of Na2SO4 supporting electrolyte is added to the cathode chamber.

[0087] S3, a nano-silver modified carbon paper electrode with a deposition time of 40s is installed in the anode chamber, and a stainless steel electrode with the same area is installed in the cathode chamber, the power supply of the electrochemical reactor is turned on, and the current is set to 60mA / cm 2 , the anode and cathode chambers are accompanied by stirring at a rate of 600rmp during the reaction process; the current and the color change of the wastewater are monitored during the reaction process;

[0088] S4, after 2h treatment, the power switch is turned off, the drainage system of the anode chamber of the reactor is opened, and the treated wastewater is discharged.

[0089] Example 11

[0090] The difference from example 10 is only that 20mmol / L of sodium phosphate is added.

[0091] Example 12

[0092] The difference from example 10 is only that 20mmol / L of sodium carbonate is added.

[0093] Example 13

[0094] The difference from example 10 is only that 3mmol / L of sodium chloride is added.

[0095] Examples 10-13 mainly investigate the effect of water background components on the degradation of acid orange 74 by three-dimensional electro-activated persulfate, specifically as Figure 4 When 20 mmol / L of sodium phosphate was added, the removal rate of acid orange 74 was only 71.7% after 3 h, and the corresponding pseudo-first-order kinetic degradation rate constant was only 0.41, which was 56.8% lower than that without the addition of sodium phosphate, indicating that sodium phosphate had an inhibitory effect on three-dimensional electro-activated persulfate. Similarly, when 20 mmol / L of sodium carbonate was added, the removal rate of acid orange 74 was 73.7% after 3 h, and the corresponding pseudo-first-order kinetic degradation rate constant was only 0.46, indicating that sodium carbonate also had an inhibitory effect on three-dimensional electro-activated persulfate, but the inhibitory effect was slightly smaller than that of sodium phosphate. In contrast, when 3 mmol / L of sodium chloride was added, the complete removal of acid orange 74 was achieved in only 40 min, and the pseudo-first-order kinetic degradation rate constant was as high as 8.8, which was 9.3 times that without the addition of sodium chloride, indicating that sodium chloride could greatly improve the efficiency of three-dimensional electro-activated persulfate.

[0096] The embodiments of the present application do not exhaust the technical scope of the point of protection claimed by the present application, and the new technical solutions formed by the same or multiple technical features in the technical solutions of the embodiments are also within the scope of protection claimed by the present application, and all the parameters involved in the present application do not have non-replaceable unique combinations with each other unless specifically stated.

[0097] Those skilled in the art will readily understand that the above description of the preferred embodiments of the present application is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for three-dimensional electro-activated persulfate high-efficiency treatment of refractory organic pollutants, characterized by: The method adopts an IrO2 electrode as an anode, a stainless steel plate as a cathode, and the nano-silver particle / reduced graphene oxide hydrogel as a particle electrode to form a three-dimensional electrode reaction system, and the method adds the wastewater to be treated and persulfate and processes after connecting the power supply; the nano-silver particles are uniformly loaded between the layers of the reduced graphene oxide.

2. The method of claim 1, wherein the method is characterized in that, The nano-silver particle / reduced graphene oxide hydrogel has a water content of 70-90 wt%.

3. The method of claim 1, wherein the method is characterized by, The nano-silver particle / reduced graphene oxide hydrogel particle electrode is prepared by a low-temperature hydrothermal reduction method, specifically, a graphene oxide aqueous solution, an AgNO3 solution and a NaHSO3 solution are used as reaction precursors, which are uniformly mixed in a sealed reaction bottle and reacted at 70-90℃ in a water bath for 10-20h until the hydrogel is gradually self-assembled.

4. The method of claim 3, wherein the method is characterized by, The graphene oxide aqueous solution has a concentration of 0.6mg / L, the AgNO3 solution has a concentration of 0.3mmol / L, the NaHSO3 solution has a concentration of 0.3mg / mL, the water bath heating temperature is 80℃, and the reaction time is 15h.

5. The method for treating recalcitrant organic pollutants according to any one of claims 1-4, wherein the method is characterized by, The method comprises the following steps: S1, in a single-chamber reactor, a certain amount of wastewater to be treated and persulfate are added, an IrO2 electrode and a stainless steel plate electrode with the same area are loaded, and the nano-silver particle / reduced graphene oxide hydrogel is filled to construct a three-dimensional electro-activation system; S2, the IrO2 electrode is used as an anode, the stainless steel plate is used as a cathode, the power supply is connected, and the changes of the current, voltage and pollutant concentration in the reaction process are monitored; S3, after the reaction is completed, the particle electrode in the reactor is recovered, and the treated wastewater is discharged.

6. The method of claim 5, wherein the three-dimensional electrically activated persulfate efficiently treats recalcitrant organic pollutants. In the step S1, the persulfate is sodium persulfate.

7. The method of claim 1-4, wherein the method is characterized in that, Na2SO4 is further added in the wastewater.

8. The method of claim 1-4, wherein the method is characterized in that, NaCl is further added in the wastewater.

9. The method of claim 1-4, wherein the method is characterized in that, The wastewater is an azo dye acid orange 74.

10. The method of claim 3-9, wherein the method is characterized in that, The step S2 controls the current density to be 20-40 mA / cm 2 after the power is turned on, and the voltage is not more than 15 V.

11. The method of claim 10, wherein the three-dimensional electrically activated persulfate efficiently treats recalcitrant organic pollutants. The current density is 30 mA / cm 2 .

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