Method for in situ generation of dichlorine monoxide in high chlorine water environment

Abstract

The present invention relates to a method for in-situ generation of dichlorine monoxide in a water environment and accurate control of the concentration of the generated dichlorine monoxide, comprising: adding free chlorine in a dosage of 2 to 5 mgCl2 / L to the water environment, inducing HOCl and / or ClO in the water environment ‑ The water environment has an initial chloride ion concentration of 0.1 M or more, wherein the free chlorine is selected from HOCl, ClO ‑ , Cl2, Cl2O and any combination thereof. The concentration of the generated dichlorine monoxide can be precisely controlled by adjusting the free chlorine concentration, the chloride ion concentration of the water environment, the pH value, the type and concentration of the non-chlorine anions / cations contained, wherein the pH value is 4.33-8.60, the non-chlorine anions include carbonate, bicarbonate, phosphate, dihydrogen phosphate, monohydrogen phosphate, etc., and the cations include potassium ions, sodium ions, magnesium ions, etc.

Description

Technical Field

[0001] The present invention relates to the field of dichlorine monoxide preparation, and in particular, to a method for forming dichlorine monoxide in a high-chlorine water environment and being able to accurately control the concentration of the generated dichlorine monoxide, and a use of the method for treating pollutants. Background Art

[0002] Free chlorine has been widely used as a disinfectant in drinking water treatment since the early 20th century, and is also used as an oxidant in municipal and industrial water treatment to remove color and degradable organic pollutants as well as compounds that cause taste and odor. In aqueous solutions containing free chlorine, free chlorine species are present as hypochlorous acid / hypochlorite (HOCl / ClO - ), molecular chlorine (Cl2) and dichlorine monoxide (Cl2O). For drinking water, HOCl / ClO - is the most abundant free chlorine species, while Cl2 and Cl2O are minor species. However, these two minor species are highly reactive with many organic pollutants, with their second-order reaction rate constants being much higher than HOCl / ClO. - The second-order reaction rate constant is 2-7 orders of magnitude higher. Although the reactivity of Cl2O to organic pollutants is sometimes higher than that of Cl2, the contribution of Cl2O to pollutant degradation in the chlorination process is often ignored.

[0003] Cl2O gas was first discovered and identified in 1834 as a light orange-yellow gas that readily dissolves in and reacts with water. Cl2O can react with saturated alkanes (e.g., 1-chlorobutane, 1-chloropropane, and n-butyronitrile) to form chloroalkanes by free radical substitution reactions, can react with unsaturated olefins (e.g., trichloroethylene) by addition reactions to produce carbonyls or ethers on the olefin, and can react with aromatic compounds by side chain substitution or electrophilic substitution, depending on the functional group attached to the aromatic compound. Cl2O is often used as an effective bleaching agent for wood pulp because it reacts with insoluble lignin in wood pulp by electrophilic chlorination, demethylation, and oxidation processes.

[0004] High purity Cl2O gas can be generated by passing Cl2 gas into a heated inert solid carrier containing HgO, carbonate or phosphate (see the following reaction formula 1-3):

[0005] 2Cl2+nHgO→HgCl2·Cl2(n-1)HgO+Cl2O Reaction 1

[0006] 2Cl2+2Na2CO3+H2O→Cl2O+2NaHCO3+2NaCl Reaction 2

[0007] 2Cl2+2Na3PO4+H2O→Cl2O+2Na2HPO4+2NaCl Reaction 3

[0008] The generated Cl2O gas is rapidly hydrolyzed into HOCl in water, and HOCl and Cl2O form an equilibrium relationship (see reaction equation 4)

[0009] K1=87M -1 Reaction 4

[0010] Therefore, a major strategy for the formation of Cl2O to degrade pollutants in the field of water treatment is to add high concentrations of free chlorine aqueous solution (500-600 μM at pH 4-9). In most cases, the addition of such high concentrations of free chlorine aqueous solution is not feasible because it significantly increases the chemical cost of the treatment process and causes subsequent residual chlorine removal steps, and has potential safety issues during operation.

[0011] Studies have reported that Cl2O can degrade Ni(II)(CN)4 2- The contribution of Cl2O to the degradation of Ni(II)(CN)4 was enhanced by increasing the chloride concentration from 1.3 mM to 33 mM in an acetic acid buffered solution at pH 5. The other two chloride-containing reaction species, Cl2 and HOCl / ClO, contributed significantly to the degradation of Ni(II)(CN)4 2- The contribution of Cl2O to Ni(II)(CN)4 2- The reaction rate constant is much smaller. The promoting effect of chloride ions on the formation of Cl2O cannot be explained by the current knowledge for the generation of Cl2O in water, and the method of using the equilibrium constant of Equation 4 to calculate the concentration of Cl2O in the presence of chloride ions needs to be re-evaluated. Nevertheless, based on the report, the inventors of this case tried to form Cl2O for rapid degradation of organic pollutants with a small concentration of free chlorine at high chloride ion concentrations. Through extensive research and experiments, the inventors proposed a new mechanism of action to generate Cl2O in situ in a high-chlorine aqueous solution, and the method can accurately control the concentration of generated chlorine monoxide, thereby completing the present invention. Summary of the invention

[0012] In the mechanism proposed by the present invention, in addition to HOCl / ClO - In addition, chloride ion is also an important reactant. This mechanism has potentially opened up a new way to carry out chlorination by adding a certain amount of free chlorine, which can be used to degrade organic pollutants in water containing a high chloride ion concentration of more than or equal to 0.1M, such as in seawater, brackish groundwater, ballast water, landfill leachate and hydraulic fracturing wastewater. This mechanism proposed by the present invention can also show the contribution of Cl2O to pollutant degradation that has been ignored in this area. In addition, the method proposed by the present invention can also be used for any other field that needs Cl2O.

[0013] In one aspect of the present invention, a method for in situ generation of dichlorine monoxide in an aqueous environment is provided, comprising: adding free chlorine to the aqueous environment at a dosage of 2 to 5 mgCl2 / L, inducing HOCl and / or ClO in the aqueous environment; - to generate chlorine monoxide; wherein the water environment has an initial chloride ion concentration greater than or equal to 0.1M, and wherein the free chlorine is selected from HOCl, ClO - , Cl2, Cl2O and any combination thereof.

[0014] In one embodiment, the chlorine-containing water environment or high-chlorine-containing water environment refers to water with a chloride ion concentration greater than or equal to 0.1 M. In a preferred embodiment, the water environment has an initial chloride ion concentration of 0.2-1.0 M, for example, the initial chloride ion concentration can be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75 or 0.8 M. In another embodiment, the free chlorine is an alkali metal hypochlorite or an alkaline earth metal hypochlorite, such as sodium hypochlorite.

[0015] In one embodiment, the pH of the water environment is 4-9, such as 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5 or 9.0. If the initial pH of the water environment does not meet the above range, acid and / or hydroxide can be used to adjust, such as before or simultaneously adding free chlorine. In this embodiment, acid can be an acid common in the art, such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, etc., and hydroxide can be an alkali metal hydroxide or an alkaline earth metal hydroxide, such as sodium hydroxide, potassium hydroxide, etc. In a further embodiment, a solution comprising carbonate, bicarbonate, phosphate, dihydrogen phosphate, monohydrogen phosphate and any combination thereof can be used for buffering.

[0016] In one embodiment, before adding the free chlorine, the chloride ion concentration of the water environment is adjusted to have a chloride ion concentration greater than or equal to 0.1 M. For example, a salt containing chloride ions may be added to adjust the chloride ion concentration of the water environment, such as ammonium chloride, sodium chloride, potassium chloride, magnesium chloride, etc.

[0017] In one embodiment, the concentration of the generated chlorine monoxide is controlled by adjusting the concentration of free chlorine in the water environment; the chloride ion concentration, pH value, the type and concentration of the non-chlorine anions and / or cations contained in the water environment. In this embodiment, chloride ions and pH value can adopt the above range, such as chloride ion concentration can be 0.2-1.0M, and pH value can be 4-9, such as 4.33-8.60. In this embodiment, non-chlorine anions can include carbonate, bicarbonate, phosphate, dihydrogen phosphate, monohydrogen phosphate, and its concentration is greater than or equal to 5mM, such as 10,15,20,25 or 30mM, and cations can include alkali metal ions or alkaline earth metal ions, such as potassium ions, sodium ions, magnesium ions, and its concentration is 0.05-1M, such as 0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9 or 1M.

[0018] In another aspect of the present invention, a method for treating pollutants in a chlorine-containing water environment is provided, comprising: adding free chlorine to the water environment at a dosage of 2 to 5 mgCl2 / L, inducing HOCl and / or ClO in the water environment. - Chlorination to generate dichlorine monoxide; reacting dichlorine monoxide with the pollutant, wherein the water environment has an initial chloride ion concentration greater than or equal to 0.1M, and wherein the free chlorine is selected from HOCl, ClO - , Cl2, Cl2O and any combination thereof

[0019] In another embodiment, the water environment refers to water containing any chlorine-containing substances, for example, HOCl, ClO - , Cl - In a preferred embodiment, the chlorine-containing water environment has an initial chloride ion concentration of 0.2-1.0M, for example, the initial chloride ion concentration can be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75 or 0.8M.

[0020] In one embodiment, the pH of the water environment is 4-9, such as 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5 or 9.0. If the initial pH of the water environment does not meet the above range, acid and / or hydroxide can be used to adjust, such as before or simultaneously adding free chlorine. In this embodiment, acid can be an acid common in the art, such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, etc., and hydroxide can be an alkali metal hydroxide or an alkaline earth metal hydroxide, such as sodium hydroxide, potassium hydroxide, etc. In a further embodiment, a solution comprising carbonate, bicarbonate, phosphate, dihydrogen phosphate, monohydrogen phosphate and any combination thereof can be used for buffering.

[0021] In one embodiment, before adding the free chlorine, the chloride ion concentration of the water environment is adjusted to have a chloride ion concentration greater than or equal to 0.1 M. For example, a salt containing chloride ions may be added to adjust the chloride ion concentration of the water environment, such as ammonium chloride, sodium chloride, potassium chloride, magnesium chloride, etc.

[0022] In one embodiment, the concentration of the generated chlorine monoxide is controlled by adjusting the concentration of free chlorine in the water environment; the chloride ion concentration, pH value, the type and concentration of the non-chlorine anions and / or cations contained in the water environment. In this embodiment, chloride ions and pH value can adopt the above range, such as chloride ion concentration can be 0.2-1.0M, and pH value can be 4-9, such as 4.33-8.60. In this embodiment, non-chlorine anions can include carbonate, bicarbonate, phosphate, dihydrogen phosphate, monohydrogen phosphate, and its concentration is greater than or equal to 5mM, such as 10,15,20,25 or 30mM, and cations can include alkali metal ions or alkaline earth metal ions, such as potassium ions, sodium ions, magnesium ions, and its concentration is 0.05-1M, such as 0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9 or 1M.

[0023] In one embodiment, the pollutant is an aromatic pollutant with an electron donating functional group. In a further embodiment, the pollutant is an aromatic pollutant containing a hydroxyl, an amine or a methoxy group. In yet another embodiment, the chlorine-containing water environment is brackish groundwater, reverse osmosis brine, hydraulic fracturing wastewater, ballast water or landfill leachate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are included to provide a further understanding and explanation of the inventive concept, and illustrate embodiments of the inventive concept and together with the description serve to explain the principles of the inventive concept. In the drawings:

[0025] Figure 1Schematic diagram showing the mechanism of the generation of Cl2O from chloride ions and free chlorine in a chloride ion-containing aqueous solution.

[0026] Figure 2 The effect of chloride ion concentration on CBZ degradation is shown, where (a) shows the CBZ degradation kinetics that vary with chloride ion concentration; (b) shows the chloride decay during CBZ chlorination at different chloride ion concentrations, conditions: [free chlorine] 0 = 2 mgCl2 / L, pH = 7.50, [CBZ] 0 = 5 μM.

[0027] Figure 3 The kinetics of CBZ degradation at a sulfate concentration of 0.75 M are shown, under the conditions: [free chlorine] 0 = 2 mgCl 2 / L, pH = 7.50, [CBZ] 0 = 5 μM.

[0028] Figure 4 Shows the decay of chlorine in the absence of CBZ, conditions: [Cl - ]=1.00M, [free chlorine]0=2mgCl2 / L, pH=7.50.

[0029] Figure 5 The kinetics of CBZ degradation as a function of chloride concentration are shown, with free chlorine doses of 2 or 5 mgCl2 / L, conditions: pH 7.50, [CBZ]0 = 5 μM.

[0030] Figure 6 Shown are (a) CBZ degradation kinetics in the absence of additional chloride ions at pH 4.40 and at 0.2 M chloride ions at pH 7.50; (b) chloride decay during CBZ chlorination in the absence of additional chloride ions at pH 4.40 and at 0.2 M chloride ions at pH 7.50, conditions: [free chloride] 0 = 2 mgCl2 / L, [CBZ] 0 = 5 μM.

[0031] Figure 7 It is shown that when the chlorine concentration is 2 and 5 mgCl2 / L, [Cl - ] and k CBZ 'Correlation between, condition: [CBZ]0 = 5 μM.

[0032] Figure 8 CBZ degradation is shown at a sulfate concentration of 0.10 M and pH 4.65, conditions: [free chlorine] 0 = 2 mgCl2 / L, [CBZ] 0 = 5 μM.

[0033] Fig. 9 The degradation kinetics of CBZ at different pH values ​​are shown. - ]=0.2M, [free chlorine]0=2mgCl2 / L, [CBZ]0=5μM.

[0034] Fig.10 The degradation kinetics of CBZ in different buffer systems are shown. - ]=0.2M, [free chlorine]0=2mgCl2 / L, [CBZ]0=5μM.

[0035] Fig.11 The degradation kinetics of CBZ when pH was adjusted using NaOH / HCl and phosphate buffer systems, respectively, under the conditions of pH = 7.50, [Cl - ]=0.2M, [free chlorine]0=2mgCl2 / L, [CBZ]0=5μM.

[0036] Fig.12 The degradation kinetics of CBZ under different cation systems are shown. - ]=0.1M, [free chlorine]0=2mgCl2 / L, [CBZ]0=5μM.

[0037] Fig.13 Figure 2 shows (a) DMOB degradation kinetics as a function of chloride concentration, conditions: [free chlorine] 0 = 2 mgCl2 / L, pH = 7.50, [DMOB] 0 = 5 μM; (b) BPA degradation kinetics in the absence of additional chloride and pH 7.50 and at 0.2 M chloride and pH 7.50, conditions: [free chlorine] 0 = 2 mgCl2 / L, [BPA] 0 = 5 μM; (c) BA degradation kinetics at 0.2 M chloride and pH 7.50, conditions: [free chlorine] 0 = 2 mgCl2 / L, [BA] 0 = 5 μM; (d) CBZ degradation kinetics in the presence of 0.5, 1 and 2 mgDOC / L NOM, conditions: [Cl - ]=1.0M, [free chlorine]0=5mgCl2 / L, [CBZ]0=5μM.

[0038] Fig.14Shown are (a) the chloride decay in the chlorination of DMOB as a function of chloride ion concentration, conditions: [free chloride] 0 = 2 mgCl2 / L, pH = 7.50, [DMOB] 0 = 5 μM; (b) the chloride decay in the chlorination of BPA in the absence of additional chloride ions and pH 7.50 and at 0.2 M chloride ions and pH 7.50, conditions: [free chloride] 0 = 2 mgCl2 / L, [BPA] 0 = 5 μM; (c) the chloride decay in the chlorination of BA at 0.2 M chloride ions and pH 7.50, conditions: [free chloride] 0 = 2 mgCl2 / L, [BA] 0 = 5 μM; (d) the chloride decay in the chlorination of NOM in the absence of additional chloride ions or CBZ, at 1.00 M chloride ions but without CBZ, and at 1.00 M and 5 μM chloride ions and CBZ, conditions: [free chloride] 0 = 5 mgCl2 / L, pH = 7.50.

[0039] Fig.15 Shown are (a) DMOB degradation kinetics in the absence of additional chloride ions and pH 4.40 and at 0.75 M chloride ions and pH 7.50, conditions: [free chlorine] 0 = 5 mgCl2 / L, [DMOB] 0 = 5 μM; (b) chlorine decay in DMOB chlorination in the absence of additional chloride ions and pH 4.40 and at 0.75 M chloride ions and pH 7.50, conditions: [free chlorine] 0 = 5 mgCl2 / L, [DMOB] 0 = 5 μM; (c) degradation of DMOB in the presence of different HOBr concentrations, conditions: [DMOB] 0 = 5 μM, pH = 7.50.

[0040] Fig.16 Shown are the forms of phosphoric acid at different pH.

[0041] Fig.17 Shows the form of carbonic acid at different pH DETAILED DESCRIPTION

[0042] In the following description, for the purpose of explanation, many specific details are set forth to provide a thorough understanding of various embodiments. However, various embodiments can be practiced without these specific details, or can be practiced with one or more equivalent arrangements. Although the present invention is further described in detail in conjunction with specific examples, the scope of the present invention is not limited thereto.

[0043] In the examples herein, free chlorine was added to solutions containing high concentrations of chloride ions to elucidate the role of Cl2O in the degradation of micropollutants and the role of chloride ions in the Cl2O formation mechanism. Carbamazepine (CBZ) was selected as a model compound because it is a difficult-to-degrade pollutant frequently detected in water sources. The following examples can be used to (1) study the effect of chloride ion concentration on the degradation kinetics of CBZ in chlorination reactions; (2) distinguish the contribution of different free chlorine species to CBZ degradation, thereby confirming a new Cl2O formation mechanism; (3) evaluate the performance of Cl2O in degrading CBZ at different pH values, different non-chloride anions, and different cations, and its reactivity to different organic structures.

[0044] In this article, unless otherwise specified, all methods, steps and operations were carried out at ambient temperature (22±2°C).

[0045] As used herein, the terms "high chloride water (environment)", "water (environment) containing high chloride", and "water (environment) containing high chloride ions" refer to water (environment) with a chloride ion concentration greater than or equal to 0.1 M, and throughout the text, these terms can be equivalently replaced.

[0046] In the examples herein, sodium hypochlorite (NaClO) solution (4.0-5.0%), sodium chloride (NaCl), sodium hydroxide (NaOH), sodium bromide (NaBr), sodium dihydrogen phosphate (Na2HPO4), sodium hydrogen phosphate (NaH2PO4), sodium carbonate (Na2CO3), sodium bicarbonate (Na2HCO3), sodium sulfate (Na2SO4), carbamazepine (CBZ), 1,4-dimethoxybenzene (DMOB), bisphenol A (BPA), benzoic acid (BA), ascorbic acid (HC6H7O6), sulfuric acid (H2SO4), phenylenediamine sulfate (DPD), ethylenediaminetetraacetic acid (EDTA) were purchased from Sigma-Aldrich, USA. HPLC-grade phosphoric acid (H3PO4) and methanol were purchased from Fisher Scientific, USA. All solutions were prepared by dissolving reagent-grade chemicals in double deionized water (DDI, 18.2 μm-cm) produced by a water purification system (Cascada, PALL Corporation). Suwannee River reverse osmosis natural organic matter (NOM) isolate (Cat No.: 2R101N) was purchased from the International Humic Substances Society. NOM stock solution was prepared by adding NOM isolate to DDI water, stirring overnight, and then filtering through a 0.45 μm pore size fiber membrane (Whatman). Free chlorine stock solution was prepared by diluting NaClO solution (4.0-5.0%) with DDI water. The concentration of free chlorine stock solution was calibrated (2.60 gCl2 / L). All prepared stock solutions were stored at 4°C in the dark and allowed to return to ambient temperature (22 ± 2°C) before use.

[0047] In the embodiment provided herein, generalized operating steps are as follows.The degradation of micropollutants is studied in a cylindrical glass reactor having a diameter of 11 cm containing 250 mL of the aqueous solution. Reactor is placed on a magnetic plate. Prepare 250 mL of the aqueous solution by adding 1.00 M NaCl and micropollutant stock solution of a specified amount in DDI water, realize the different chloride ion concentrations of 0.05-1.00 M and the target micropollutant dosage of 5 μM respectively. In the CBZ chlorination process, by 5 mM phosphate buffer (by mixing the Na of 0.20 M of different proportions HPO4, 0.20 M NaHPO4 and 14.57 M HPO4 preparation), it is 4.33, 5.50, 5.90, 6.44, 6.97 and 7.50 that solution is buffered to pH. Then by adding the free chlorine stock solution of a specified volume to the 250 mL aqueous solution to reach the initial chlorine concentration of 2 or 5 mgCl2 / L, test is carried out. At predetermined time intervals, 1.0 mL samples were collected, quenched with ascorbic acid at an ascorbic acid / initial chlorine molar ratio of 1.5 / 1, and then analyzed for residual micropollutant concentrations. In a parallel experiment, chlorine concentrations were measured at predetermined time intervals.

[0048] Except using 5mM bicarbonate buffer (by mixing different proportions of 0.20M Na2CO3 and NaHCO3 preparation) and dropwise adding 200mM NaOH and 0.60M HCl (pH is continuously monitored by pH meter (ORION STAR Aiii)) to buffer pH, the influence of carbonate and hydroxide on micropollutant degradation is detected in a similar manner as above. The influence of NOM and different organics (i.e. DMOB, BPA and BA) with different structures is also detected in a similar manner. All experiments are repeated at least once. All data graphs represent the mean value of the experimental data of repeated test results. Origin 8.0 software is used to evaluate statistical significance (p < 0.05) by one-way analysis of variance (ANOVA).

[0049] The concentrations of CBZ, DMOB, BPA and BA were measured using a high performance liquid chromatography (VP series, Shimadzu) equipped with a Waters symmetry C18 column (4.6×150 mm, 5 μm particle size). The wavelengths of the UV detector were set to 224, 227, 225 and 230 nm for CBZ, DMOB, BPA and BA, respectively. The mobile phase used to measure CBZ, DMOB, BPA and BA consisted of water (adjusted to pH 2 by phosphoric acid) / methanol (60:40, v:v%) with a flow rate of 1 mL / min. The concentration of free chlorine was determined by the DPD colorimetric method using a UV-visible spectrophotometer (Shimadzu, Multispec-1501). A calibration curve for chlorine concentration was established at high chloride ion concentrations.

[0050] Example 1: Degradation of CBZ at different chloride ion concentrations

[0051] Figure 2 (a) shows the CBZ degradation kinetics as a function of chloride ion concentration at pH 7.50 and free chlorine concentration of 2 mgCl2 / L. Figure 2 As shown in (a), at chloride ion concentrations of 0.05 and 0.10 M, CBZ does not degrade during the chlorination process. This is consistent with previous research results, that is, at chloride ion concentrations of 1-10 mg / L, CBZ is able to resist chlorination. When the chloride ion concentration increases to 0.20, 0.50, and 0.75 M, the degradation of CBZ during the chlorination process follows pseudo-first-order degradation kinetics, and the rate constant (k CBZ ') were 0.07, 0.66 and 1.80 min respectively -1 .

[0052] Furthermore, the test was repeated at pH 7.50 with a sulfate concentration of 0.75 M and a free chlorine dosage of 2 mgCl2 / L, and no CBZ degradation was observed within 15 minutes (see Figure 3 ). This example shows that the increased CBZ degradation rate constant at high chloride ion concentration is not caused by increased ion concentration.

[0053] Chloride consumption increases with increasing chloride ion concentration and is related to k CBZ ' has the same trend. When the chloride ion concentration was 0.20, 0.50 and 0.75 M, the chloride consumption during the 15-minute chlorination of CBZ reached 0.36, 0.66 and 0.74 mgCl2 / L respectively (see Figure 2 b) Chlorine consumption relative to the corresponding k CBZ ' increases with the increase of chlorine, indicating that at high chloride concentrations, chlorine-containing reactive species are responsible for the degradation of CBZ during the chlorination process. This is further confirmed by the negligible CBZ degradation and chlorine decay at chloride concentrations of 0.05 and 0.10 M (see Figure 2 a and b).

[0054] At a chloride concentration of 0.75 M, chlorine decay continued to occur even after all CBZ was degraded within 2 min, but chlorine did not self-decay at a chloride concentration of 1.00 M even in the absence of CBZ ( Figure 4 ). These results indicate that the chlorine-containing reactive species react continuously with the CBZ degradation products.

[0055] In addition, the CBZ degradation rate constant increases with the increase of free chlorine concentration. Figure 5As shown in the figure, as the free chlorine dose increases from 2 to 5 mgCl2 / L, when the chloride ion concentration is 0.20, 0.50 and 0.75 M respectively, k CBZ 'From 0.07, 0.66 and 1.80min -1 Increased to 0.19, 1.83 and 3.32 min respectively -1 .

[0056] In an aqueous solution containing free chlorine, the three chlorine-containing reactive species are HOCl / ClO - , Cl2 and Cl2O. As confirmed by the above experiments, Cl2O was identified as the chlorine-containing reactive species that rapidly degrades CBZ at high chlorine concentrations. Figure 6 The degradation kinetics of CBZ and the associated chloride decay in the absence of additional chloride ions (28 μM chloride ions), pH 4.40, and a free chloride concentration of 2 mgCl2 / L, as well as the degradation kinetics of CBZ and the associated chloride decay in the presence of 0.20 M chloride ions, pH 7.50, and a free chloride concentration of 2 mgCl2 / L are shown.

[0057] At pH 4.40, in the absence of additional chloride ions, HOCl was the dominant chlorine species. No CBZ degradation or chloride decay was observed, confirming that the HOCl / ClO - However, at pH 7.50 and 0.20 M chloride ion, 65% of CBZ was degraded within 15 minutes, accompanied by a significant (0.36 mgCl2 / L) chloride decay. Figure 6 The difference between the degradation of CBZ also ruled out Cl2 as the main chlorine-containing reactive species, and Cl2O was thus identified to achieve rapid degradation of CBZ.

[0058] K2=5.25×10 2 M -2 Reaction 5

[0059] For this example, when no additional chloride ions are added to the solution, the chloride ions will be present at approximately the same molar concentration as the free chlorine added to the solution. For an initial free chlorine concentration of 2 mgCl2 / L, this would correspond to a chloride ion concentration of approximately 28 μM. The pH-dependent equilibrium is explained according to the following equation: K2 can be expressed as follows

[0060]

[0061] From this, [Cl2] can be calculated based on the following equation

[0062] [Cl2]=K2[HOCl][H + ][Cl- Equation 2

[0063] When a high concentration of NaCl is added, the coefficient γ affected by the ionic strength (μ) can be considered based on the following equation: i

[0064]

[0065]

[0066]

[0067] C i is the molar concentration of ion i (M, mol / L); Z i is the charge number of ion i; the parameter A depends on the temperature T and standard conditions (water at 25°C), giving A = 0.5085 M -1 / 2 ; The additional fitting parameters bi are temperature-dependent parameters.

[0068] If the effect of ionic strength (μ) is taken into account, the pH-dependent equilibrium constants K1' and [Cl2] can be expressed in terms of activity rather than molar concentration:

[0069]

[0070] [Cl2]=K2[HOCl]{H +}{Cl - Equation 7

[0071] At a free chlorine concentration of 2 mgCl2 / L, a pH of 4.40, and no additional chloride ions (28 μM chloride ions), the effect of ionic strength can be ignored. Since the chloride ion concentration is the same as the free chlorine concentration, both are 28 μM, all known values ​​are substituted to calculate [Cl2], expressed as [Cl2]1.

[0072] [Cl2]1=K2[HOCl][H + ][Cl - ]=5.25×10 2 ×2.8×10 -5 ×1.0×10 -4.4 ×2.8×10 -5 =1.64×10 -11 M

[0073] At pH 7.50 and 0.20 M chloride ions, the ionic strength μ is 0.2 (see Eq. 3) and the activity coefficient γ i is 0.747 (see equation 4). K2′ is 9.40×10 2, corrected to 0.2 M ionic strength using the Davies equation. [Cl2] was calculated according to Equation 7 and is expressed as [Cl2]2.

[0074] [Cl2]2=K2′[HOCl]{H +}{Cl - =9.40×10 2 ×2.8×10 -5 ×(0.747×1.0×10 -7.5 )×(0.747×0.2)=9.3×10 -11 M

[0075] [Cl2]1 and [Cl2]2 are almost the same, one is 1.64×10 -11 M, and the other is 9.3×10 -11 M.

[0076] The results of the above experiments and calculations show that the formation of Cl2O requires only a low concentration of free chlorine (e.g., a few ppm), and has a good correlation with both chloride ion and free chlorine concentrations. This is different from the existing cognition in the art, and further indicates that the formation of Cl2O can follow a pathway other than the conventional pathway (e.g., reaction formula 4 above). In other words, in a solution with a high chloride ion content of not less than 0.20M, free chlorine at a level of a few ppm can show a significantly high degradation rate constant for difficult-to-degrade pollutants (e.g., carbamazepine).

[0077] Example 2: Effect of chloride ion concentration on Cl2O formation

[0078] The effect of chloride ions on the formation of Cl2O can be determined by the equation k at a fixed free chloride concentration. CBZ 'Relative to the chloride ion concentration ([Cl - ]) to quantify the reaction order.

[0079] Specifically, to quantify the effect of chloride ions on Cl2O formation, the k CBZ 'The reaction order relative to the chloride ion concentration. The pseudo-first-order degradation kinetics can be expressed as follows obs :

[0080] k obs =a[Cl - ] n Equation 8

[0081] The logarithmic transformation of Equation 8 yields Equation 9

[0082] logk obs = n log[Cl - ]+loga Equation 9

[0083] Where n represents [Cl - ] is the reaction order; a represents the coefficient of other influencing factors (such as [HOCl]).

[0084] like Figure 7 As shown, when the free chlorine concentration is 2 or 5 mgCl2 / L, by CBZ The natural logarithm of ' is relative to [Cl - The natural logarithm of ] (logk CBZ ' and log[Cl - ]) plotted, the corresponding reaction orders are 2.43 and 2.45. As shown in reaction equation 5, high concentration of chloride ions will make HOCl / ClO - The equilibrium between K and Cl2 shifts to form a higher concentration of Cl2 (see reaction 5), but k CBZ The reaction orders are 2.43 and 2.45, which are still higher than those of HOCl / ClO with only chloride ions. - The value of the case of forming Cl2 is 2. Therefore, chloride ions play two important roles, one is to promote HOCl / ClO - The other is to react with Cl2 to form polychlorinated monoanion Cl n - (n≥3).

[0085]

[0086] Additional experiments at pH 4.40 and free chlorine and sodium sulfate concentrations of 2 mgCl2 / L and 0.10 M, respectively, confirmed the role of chloride ions in the formation of Cl2 n - (n ≥ 3) is important in the conversion to Cl2O. This experiment provided almost the same Cl2 concentration as the conditions of pH 7.50 and 0.20 M chloride ions, and provided the same ionic strength, but using sulfate. No CBZ degradation was observed under this experimental condition (see Figure 8 ), whereas 65% of CBZ was degraded at pH 7.50 and 0.20 M chloride ions, indicating that neither sulfate ions nor ionic strength promote the conversion of Cl2 to Cl2O. - The reaction between Cl2 and Cl - The lone pair of electrons in Cl2 undergoes charge transfer to Cl2, resulting in partial occupation of the σ* antibonding orbital in Cl2 to weaken the chlorine-chlorine bond in Cl2. n - Therefore, it is easy to react with HOCl / ClO -An electrophilic substitution reaction occurs to form an intermediate molecule [ClOH…Cl…(Cl) n -Cl] - or [ClO…Cl…(Cl) n -Cl] 2- , in HOCl / ClO - A new oxygen-chlorine bond is formed between the oxygen atom of the chlorine atom and the weakened chlorine-chlorine bond. The intermediate molecule formed then produces Cl2O and chloride ions. The more reactive Cl with a weaker chlorine-chlorine bond n - Promotes the conversion of Cl2 to HOCl / ClO - Converted to Cl2O.

[0087] Based on the above experiments and Figure 1 The schematic diagram shows the pathway for the formation of Cl2O from chloride ions and free chlorine in aqueous solutions containing concentrated chloride ions. The presence of high concentrations of chloride ions helps the conversion of HOCl to Cl2 (see reaction equation 5). Chloride ions then react with Cl2 to form Cl n - (See the following reaction formula 6, Cl3 - As polychlorinated monoanion Cl n - Cl3 - With HOCl / ClO - Reaction to form Cl2O and regenerate Cl - (See reaction equations 7 and 8). The generated Cl2O and CBZ react rapidly or hydrolyze to form HOCl / ClO - It can be seen that the present invention proposes the important role of chloride ions in the Cl2O formation pathway.

[0088]

[0089]

[0090]

[0091] Example 3: Effect of pH on Cl2O formation

[0092] By plotting k at chloride ion concentration and free chloride concentration of 0.20 M and 2 mgCl2 / L, respectively CBZ The effect of pH on the formation of Cl2O was investigated by using a pH-dependent graph. The solution was controlled at different pH values ​​using phosphate buffer or NaOH / HCl. Fig. 9 As shown, when the pH of the solution is controlled by NaOH / HCl, as the pH decreases from 8.60 to 8.10, 7.50, 6.97, 6.44, 5.90 and 4.33, k CBZ'Increased from 0.01 to 0.03, 0.1, 0.33, 0.85, 2.39, 3.49 and 6.65min respectively -1 . Decreasing pH increases [H + ], which shifts the equilibrium of reaction equation 5 toward the direction of producing more Cl2, promoting the formation of Cl2O and thus increasing k CBZ '. However, when the pH of the solution was maintained by NaOH / HCl, k CBZ The slope from 6.44 to 4.33 is steeper than that from 8.60 to 6.97. The two different slopes at different pH indicate that in addition to [H + ] There is another factor that affects k CBZ '. In this regard, the inventor believes that, in addition to [H + ] In addition, the increase of HOCl concentration will also affect k CBZ ', resulting in a steeper slope observed at more acidic pH. As shown in reaction equation 8, due to Cl3 - and ClO - The electrostatic repulsion between the anion reactant Cl3 - The reaction with HOCl is more than that with its anionic analog ClO - When the pH value increases from 6.44 to 6.97, the ratio of HOCl to ClO- in the solution decreases from 6.5:1 to 1.9:1 because the pKa of HOCl / ClO- changes from 7.55 at low chloride concentration to 7.25 at high chloride concentration (at 25°C). - The increase in the concentration and the decrease in the HOCl concentration gradually changed the slope of kCBZ'.

[0093] Example 4: Effect of Weakly Acidic Anions on Cl2O Formation

[0094] The effect of common weak acid anions, such as phosphate and carbonate, on Cl2O formation was investigated by measuring CBZ degradation at chloride and free chloride concentrations of 0.20 M and 2 mgCl2 / L, respectively. pH 7.50 was buffered by the addition of phosphate or bicarbonate or maintained by the addition of NaOH (e.g. Fig.10 The pH was maintained by adding sodium hydroxide CBZ ' is 0.10min -1 , which is higher than the value with bicarbonate buffer (0.09min -1 ) and the value with phosphate buffer (0.07min -1 ) were 1.11 and 1.43 times higher. The k CBZ 'It is mainly due to the presence of weak acid anions in the solution, namely HPO4 2- / H2PO4 -and CO3 2- / HCO3 - It will promote the hydrolysis of Cl2O to generate HOCl / ClO - , following a similar path in the presence of acetic acid as mentioned in previous studies. 2- / H2PO4 - The hydrolysis ratio in the presence of CO3 2- / HCO3 - It is stronger under the presence of ions because of the nucleophilicity, i.e. the overall ionic charge, HPO4 2- / H2PO4 - Stronger.

[0095] At pH 7.50, two forms of phosphate buffer (HPO4 2- / H2PO4 - ), two forms of bicarbonate buffer (CO3 2- / HCO3 - ) and two forms of HOCl / ClO - The ratios between 1 and 2 are 16.95, 0.03, and 97.72, respectively. Specifically, for phosphoric acid, when there is no additional NaCl, the ionic strength is negligible, and the phosphoric acid dissociation constant (pK a1 ), dihydrogen phosphate dissociation constant (pK a2 ) and the monohydrogen phosphate dissociation constant (pK a3 ) are 2.15, 7.21 and 12.35 respectively. According to Johansson's research, when the solution salinity (S‰) increases to 11.7g / Kg (0.2MNaCl), pK′ a1 , pK′ a2 and pK′ a3 to 1.76, 6.27, and 9.36, respectively. Using the pK′ of phosphate a1 , pK′ a2 and pK′ a3 , the forms of phosphoric acid at different pH values ​​can be obtained (see Fig.16 ). At pH 7.50, dihydrogen phosphate (H2PO4 - ) and monohydrogen phosphate (HPO4 2- ) in 5 mM phosphate buffer solution were 5.5% and 93.2%, respectively.

[0096] For carbonate and bicarbonate, when no NaCl is added and the ionic strength is neglected, the carbonate dissociation constant (pK a1 ) and the bicarbonate dissociation constant (pK a2) are 6.12 and 9.41 respectively. When the solution salinity (S‰) increases to 11.7 g / Kg (0.2 M NaCl), pK′ a1 and pK′ a2 to 5.99 and 9.24, or 5.82 and 8.60, respectively. Similarly, using the pK′ of carbonic acid a1 and pK′ a2 , the forms of carbonic acid at different pH can be obtained (see Fig.16 ). At pH 7.50, bicarbonate (HCO3 - ) and carbonates (CO3 2- ) in 5 mM bicarbonate buffer solution were 95.3% and 2.9%, respectively.

[0097] The dissociation constant pK' of hypochlorous acid (HOCl) a is 7.5 (μ = 0, 25 ° C). When the solution salinity (S‰) increases to 11.7 g / Kg (0.2M NaCl), pK' a Reduced to 7.25.

[0098] Therefore, the trend of the overall ionic charge is consistent with their nucleophilicity, i.e., phosphate buffer > carbonate buffer > HOCl / ClO - .

[0099] Furthermore, in the presence of phosphate or bicarbonate, at high chloride concentrations, k at environmentally relevant pH CBZ ' did not decrease significantly and was still higher than k at low chloride concentrations CBZ 'Much higher (such as Fig.11 When buffered with bicarbonate buffer, the k of pH 7.50 CBZ ' is higher than with phosphate buffer but lower than with sodium hydroxide, so at high chloride concentrations and environmentally relevant pH, k in the presence of bicarbonate is CBZ ' should be between phosphate buffer and NaOH / HCl, but still well above the k for low chloride concentrations CBZ '.

[0100] Example 5: Effect of cations on Cl2O formation

[0101] Fig.12 It is shown that under different cations, namely 0.05M Mg 2+ , 0.1M Na + 、0.1MK + The degradation of CBZ under the presence of Mg 2+ 、Na + , K + K CBZThe influence of ' satisfies K + >Na + >Mg 2+ The trend of 0.05 MK + In the presence of cations and a chloride ion concentration of 0.1 M, CBZ was completely degraded within 30 seconds. This shows that the presence of cations has a significant effect on the formation of Cl2O, and the concentration of generated Cl2O can be controlled by controlling the type and concentration of cations.

[0102] Example 6: Reactivity towards different organic structures

[0103] In this example, the reactivity of ClO towards aromatic pollutants containing methoxyl, hydroxyl and carboxyl groups (represented by DMOB, BPA and BA, respectively) was compared with the reactivity of ClO towards CBZ with amine groups. The degradation of DMOB during the chlorination process showed a similar trend to that of CBZ at different chloride ion concentrations (see Fig.13 a). DMOB was not degraded at 0.10 and 0.20 M chloride ion concentrations, while k DMOB 'At 0.50, 0.75 and 1.00 M chloride ion concentrations, the temperature reached 0.05, 0.13 and 0.25 min, respectively -1 During the 15-minute chlorination period, the chlorine consumption increased from 0.20, 0.45 mgCl2 / L to 0.54 mgCl2 / L (see Fig.14 a).

[0104] In the absence of additional chloride ions and at pH 4.40, there was no DMOB degradation at a free chlorine concentration of 5 mgCl2 / L (see Fig.15 a) or chlorine decay (see Fig.15 b), which confirms that HOCl / OCl - Unable to degrade DMOB. At pH 7.50 and 0.75 M chloride concentration, in the presence of 5 mgCl2 / L of free chlorine, DMOB was almost completely degraded (100%) within 15 minutes, accompanied by a significant chlorine decay (0.35 mgCl2 / L). Fig.15 The Cl2 concentrations under the two conditions shown in a are similar, and the difference in DMOB degradation also excludes Cl2 as a chlorine-containing reactive species, which confirms that Cl2O is responsible for DMOB degradation. In addition, in DMOB chlorination, tests were performed under conditions of HOBr concentrations of 10, 20, and 50 μM and pH 7.50. 10, 20, and 50 μM HOBr only contributed almost the same effect in chlorination, i.e., 5-6% DMOB degradation (see Fig.15 c), which excludes the effect of 0.5% bromide ions in NaCl on the rapid DMOB degradation in chlorination.

[0105] This confirms that Cl2O (rather than HOCl / OCl - , Cl2 or HOBr) for DMOB degradation (see Fig.15 ). However, at the same chloride ion concentration, k DMOB 'In chlorination, less than k CBZ ', indicating that Cl2O reacts more slowly with aromatic compounds linked to methoxy groups than with aromatic compounds linked to amines.

[0106] Fig.13 Figure b shows the degradation kinetics of BPA at 2 mgCl2 / L free chlorine concentration and pH 7.50 without additional chloride ions (28 μM chloride ions) and 0.20 M chloride ions. The pseudo-first-order degradation rate constant (k BPA ') is 0.14min -1 This is attributed to the interaction between BPA and HOCl / ClO - When 0.20 M chloride ions are added at pH 7.50, k BPA 'Increase to 0.30min -1 , which is attributed to the reaction between BPA and Cl2O (0.16min -1 ) and BPA and HOCl / ClO - The reaction between (0.14min -1 ). Under the same conditions, the reaction rate constant of Cl2O to BPA (0.16min -1 ) compared to the reaction rate constant of CBZ (0.07min -1 ) is much higher, indicating that Cl2O reacts faster with aromatic compounds attached to hydroxyl groups than with aromatic compounds attached to amines. This trend is further supported by the faster chlorine decay in the presence of BPA compared to CBZ (see Fig.14 b).

[0107] BPA+HOCl→Product k=3.10-6.62×10 4 M -1 S -1 Reaction 9

[0108] Unlike DMOB, CBZ, and BPA, BA was not degraded at chloride ion and free chloride concentrations of 0.20 M and 2 mgCl2 / L, respectively, and pH 7.50 (see Fig.13 c), with negligible chlorine decay (see Fig.14c). This result indicates that ClO reacts much slower with aromatic pollutants attached to carboxyl groups than with aromatic pollutants attached to methoxy, amine or hydroxyl groups. In other words, ClO reacts faster with aromatic pollutants attached to higher electron donating functional groups, i.e., hydroxyl>amine>methoxy>>carboxyl. Since ClO undergoes mainly electrophilic aromatic substitution, functional groups with higher electron donating ability make aromatic pollutants more negatively charged, thus enhancing their reactivity to ClO.

[0109] Fig.13 Figure d shows the effect of NOM on CBZ degradation in a chlorination reaction with a chloride ion concentration of 1.00 M. The presence of 0.50, 1.00, and 2.00 mg DOC / L NOM reduced the degradation rate constant of CBZ by approximately 22%, 33%, and 54%, respectively. CBZ The decrease of ' is mainly attributed to its role as a Cl2O scavenger and HOCl / ClO - The effect of the quencher was confirmed by the chloride decay under different conditions. In the absence of additional chloride ions or CBZ, the chloride decay of 0.48 mgCl2 / L in 15 min chlorination of NOM (see Fig.14 d) is attributed to NOM and HOCl / ClO - The reaction between NOM and HOCl / ClO is oxidized and / or substituted. When 1.00 M chloride ions were added but no CBZ was added, the rapid decay of chloride within 30 seconds (1.1 mgCl2 / L) indicated that NOM rapidly scavenged Cl2O. The strong scavenging effect of NOM on Cl2O within 30 seconds was mainly due to the fact that the aromatic rings in NOM connected to electron-withdrawing groups such as hydroxyl groups were reactive toward Cl2O. The slow decay of chloride after 30 seconds (0.80 mgCl2 / L) was attributed to the interaction of NOM with HOCl / ClO. - The reaction between NOM and HOCl / ClO (0.48 mgCl2 / L) and the removal of Cl2O by NOM (0.32 mgCl2 / L) assumes that the change of NOM structure by the initial Cl2O attack does not affect the reaction between NOM and HOCl / ClO -reaction between. The weak scavenging of Cl2O by NOM after 30 seconds may be because all the reactive sites on NOM were consumed by the initial Cl2O attack. When chloride ions and CBZ were added simultaneously, the chlorine decay increased by another 0.56 mgCl2 / L, indicating that the NOM structure before the initial Cl2O attack was more reactive than CBZ, but was much less reactive thereafter. These results indicate that NOM displays a different scavenging mechanism for Cl2O compared to the scavenging mechanisms for different free radicals. The strong scavenging effect of NOM on Cl2O only exists in the initial stage of the process, because the aromatic rings in NOM connected to the electron-withdrawing groups reactive to Cl2O are all consumed within 30 seconds. Once these reactive moieties are consumed, the scavenging effect of NOM on Cl2O becomes much weaker.

[0110] In summary, according to the present invention, chloride ions can be obtained by converting HOCl / ClO - Converted to Cl2 and formed polychlorinated monoanion Cl n - , with HOCl / ClO - The reaction further generates Cl2O. Lower pH promotes Cl2 formation and produces higher concentrations of Cl2O. Weak acid anions (phosphate and bicarbonate) are stronger nucleophiles and promote the hydrolysis of Cl2O. However, in the presence of phosphate or bicarbonate, the degradation rate constant of carbamazepine at environmentally relevant pH at high chloride concentrations is still much higher than that at low chloride concentrations. Cationic Mg 2+ 、Na + , K + The effect on Cl2O generation satisfies K + >Na + >Mg 2+ The Cl2O formed reacts faster with aromatic pollutants attached to higher electron donating functional groups (i.e. hydroxyl>amine>methoxy>>carboxyl). In contrast, common free radical scavengers (natural organic substances) scavenge Cl2O strongly only at the beginning of the process, but have less impact afterwards.

[0111] Thus, the present invention proposes a new formation mechanism of a chlorine-containing reactant (Cl2O), and the generated Cl2O can degrade difficult-to-degrade pollutants, especially aromatic pollutants connected to electron-donating functional groups. The Cl2O formation mechanism of the present invention shows that only a low dose of free chlorine is required to form a significant amount of Cl2O in a high-chlorine water environment.

[0112] This opens up new opportunities for chlorination control of pollutants in seawater and wastewater containing high chloride ions (such as brackish groundwater, reverse osmosis brine, hydraulic fracturing wastewater, ballast water and landfill leachate). The use of Cl2O as an oxidant in pollutant degradation is less affected by water quality parameters (pH, alkalinity and NOM) than AOP technologies based on different free radicals. Cl2O degrades difficult-to-degrade micropollutants such as CBZ at a very fast rate over a wide pH range of 4.33-8.60. Near neutral pH, its performance is almost unaffected by bicarbonate, which is a common free radical scavenger in AOP technologies based on different free radicals. The presence of NOM mainly removes Cl2O at the beginning of the process, but has less Cl2O scavenging effect afterwards. This Cl2O formation mechanism can also show its potential role in destroying the active layer of RO membranes by oxidizing polymers based on polyamides, polybenzimidazolinones and polyoxadiazoles containing aromatic moieties in high salinity water in the presence of low concentrations of free chlorine.

[0113] Based on the Cl2O formation mechanism of the present invention, the concentrations of different free chlorine species (i.e., HOCl / ClO) can be plotted by considering the concentrations of chloride ions, free chlorine, phosphate / carbonate, and cations. - The new chlorine forms (Cl2, Cl2 and Cl2O) at different pH. In the new chlorine forms, the concentration of Cl2O is the same as that of Cl2, which will increase with decreasing pH. This change in chlorine forms indicates that the reactivity of Cl2 and Cl2O to different pollutants and their contribution to pollutant degradation are different from what is already known in the art.

[0114] Although some embodiments have been described herein, other modes and modifications will be apparent from this specification. Therefore, the inventive concept is not limited to such embodiments, but is limited to the broader scope of the appended claims and various obvious modifications and equivalent arrangements that will be apparent to those of ordinary skill in the art.

Claims

1. A method for in-situ generation of chlorine monoxide in an aqueous environment, comprising: Free chlorine is added to the water environment at a dosage of 2 to 5 mgCl2 / L to induce HOCl and / or ClO in the water environment. - Chlorination of to form dichlorine monoxide; wherein the water environment has an initial chloride ion concentration greater than or equal to 0.2M, and The free chlorine is selected from HOCl, ClO - , Cl2, Cl2O and any combination thereof, The chloride ions are obtained by converting HOCl and / or ClO - Converted to Cl2 and formed polychlorinated monoanions, and HOCl / ClO - The reaction further generates Cl2O. The pH of the water environment is 4-9, and The polychloride monoanion is Cl n - , where n≥3.

2. The method of claim 1, wherein the water environment has an initial chloride ion concentration of 0.2-1.0 M.

3. The method of claim 1, wherein the free chlorine is an alkali metal hypochlorite or an alkaline earth metal hypochlorite.

4. The method according to claim 1, wherein the pH of the water environment is 4.33-8.

60.

5. The method according to claim 1, wherein before or simultaneously with the addition of the free chlorine, an acid and / or a hydroxide is used to adjust the pH of the water environment; or before the addition of the free chlorine, the chloride ion concentration of the water environment is adjusted to have a chloride ion concentration greater than or equal to 0.2 M.

6. The method according to claim 1, wherein the concentration of the generated dichlorine monoxide is controlled by adjusting: the concentration of the free chlorine in the water environment; the chloride ion concentration, pH value, and the types and concentrations of non-chlorine anions and / or cations contained in the water environment.

7. The method of claim 6, wherein the non-chloride anions include carbonate, bicarbonate, phosphate, dihydrogen phosphate, monohydrogen phosphate, and the concentration thereof is greater than or equal to 5 mM; and the cations include alkali metal ions or alkaline earth metal ions, and the concentration thereof is 0.05-1 M.

8. The method of claim 7, wherein the cation comprises a potassium ion, a sodium ion, or a magnesium ion.

9. A method for treating pollutants in an aquatic environment, comprising: Forming dichlorine monoxide in the aqueous environment by the method of any one of claims 1-8, wherein the aqueous environment has an initial chloride ion concentration of greater than or equal to 0.2 M and a pH of 4-9; Dichlorine monoxide is allowed to react with the contaminant.

10. The method of claim 9, wherein the contaminant is an aromatic contaminant having an electron donating functional group.

11. The method of claim 10, wherein the pollutant is an aromatic pollutant containing a hydroxyl group, an amine group, or a methoxy group.

12. The method of claim 9, wherein the chlorine-containing water environment is brackish groundwater, reverse osmosis brine, hydraulic fracturing wastewater, ballast water or landfill leachate.

Images