Method and system for enhancing dehalogenation of halogenated organic matter in groundwater and simultaneous carbon dioxide mineralization and storage using carbon dioxide

Abstract

The present invention provides a method for utilizing carbon dioxide to enhance the dehalogenation of halogenated organic matter in groundwater and the simultaneous mineralization and storage of carbon dioxide, which adopts a scheme combining groundwater remediation and greenhouse gas storage, and aims to utilize carbon dioxide CO2 to enhance the dehalogenation of dissolved divalent iron (Fe) in the underground environment. II The method can effectively dehalogenate HOCs by injecting CO2 to increase the concentration of Fe in groundwater. II The dehalogenation activity of CO2 and Fe II The reaction generates stable iron carbonate FeCO₃, achieving CO₂ fixation and mineralization, thereby achieving a synergistic effect of pollution and carbon reduction, providing a new solution for groundwater remediation and climate change mitigation. This method has strong environmental and social benefits and has broad prospects for promotion and application.

Description

Technical Field

[0001] The present invention belongs to the technical fields of environmental engineering and geological engineering, and specifically relates to a method for enhancing the dehalogenation of halogenated organic matter in groundwater and the simultaneous mineralization and storage of carbon dioxide using carbon dioxide, and also relates to a system for enhancing the dehalogenation of halogenated organic matter in groundwater and the simultaneous mineralization and storage of carbon dioxide using carbon dioxide. Background Art

[0002] With the acceleration of industrialization and rapid population growth, groundwater contamination has become a global environmental problem. Halogenated organic compounds (HOCs), commonly used industrial solvents and flame retardants, form contamination plumes in groundwater, posing a serious threat to groundwater resources. Halogenated organic compounds are difficult to biodegrade, bioaccumulate, are highly toxic, and have the ability to migrate over long distances. Therefore, finding effective methods to remove halogenated pollutants from groundwater is crucial.

[0003] Fe II Mediated redox dehalogenation is an important research direction in the field of groundwater remediation. However, under natural conditions, Fe II The activity of Fe is limited and the dehalogenation efficiency is low. Therefore, researchers have been looking for ways to improve the II There are some methods for dehalogenation activity. II The mediated HOCs repair technology is disclosed in the art, wherein the reduction dehalogenation method is to remove the halogenated HOCs under standard oxygen-free conditions. II Patent CN202011119488.1 uses metal ion doping Fe(OH)2 and Fe(OH)-metal ion to form a reduction system, which achieves complete dehalogenation of HOCs in a short time and has high removal efficiency; Oxidative degradation and dehalogenation repair technology has also been widely studied in the degradation of HOCs. In the most common Fenton method, Fe II A chain reaction occurs between the mediator and H2O2, catalyzing the generation of ·OH, which has strong oxidizing ability.

[0004] At the same time, the large-scale emission of greenhouse gases, represented by carbon dioxide, has adversely affected the global climate and environment. 2+ Mg 2+ 、Fe 2+ Plasma substances react with CO2 to form solid carbonates, a method of CO2 mineralization and storage that reduces greenhouse gas emissions while preventing CO2 from escaping. On this basis, a technology combining CO2 storage with groundwater remediation would be of great significance for the management of halogenated organic matter in the environment and for carbon reduction and fixation.

[0005] Based on this, it is an urgent problem to provide a method and system that combines CO2 geological utilization with groundwater remediation technology to achieve the dual goals of pollution control and greenhouse gas storage. Summary of the Invention

[0006] One of the objectives of the present invention is to provide a method for utilizing carbon dioxide to enhance the dehalogenation of halogenated organic matter in groundwater and the simultaneous mineralization and storage of carbon dioxide.

[0007] A second object of the present invention is to provide a system for utilizing carbon dioxide to enhance the dehalogenation of halogenated organic matter in groundwater and the simultaneous mineralization and storage of carbon dioxide.

[0008] The technical solution adopted by the present invention to achieve one of the objectives is to provide a method for enhancing the dehalogenation of halogenated organic matter in groundwater and simultaneous carbon dioxide mineralization and storage using carbon dioxide, comprising the following steps:

[0009] S1, containing halogenated organic matter and Fe II CO2 is injected into the groundwater; the Fe II Including dissolved Fe II and Fe present in natural minerals II ;

[0010] S2, CO2 react with groundwater to form carbonated water. In the groundwater environment, carbonated water undergoes one or two of the following reactions: carbonated water reacts with dissolved Fe in groundwater. II The reaction forms FeCO3 particles, or H + Promote the Fe II dissolution;

[0011] S3, FeCO3 particles and dissolved Fe on the surface of natural minerals II and structural Fe II Promote the reduction, oxidation and dehalogenation of halogenated organic matter to generate Fe III ;Fe III Under the action of CO2, it co-precipitates with mineral ions in groundwater to form iron carbonate, realizing the mineralization and storage of CO2.

[0012] The general idea of ​​the present invention is as follows: Ionic Fe II It is widely distributed in underground anaerobic environments, and there are also a large number of Fe II However, these ionic Fe II The reduction and dehalogenation activity of Fe is weak, while the structural Fe in natural minerals II Based on the above analysis, the present invention provides a method for enhancing the reduction and oxidation of Fe IIThe method of mediated dehalogenation and simultaneous realization of CO2 mineralization storage adopts the method of injecting CO2 into groundwater to achieve Fe II The activity in groundwater remediation is improved, which promotes the effective dehalogenation of halogenated organic pollutants and utilizes Fe II The FeCO3 particles generated by the reaction with CO2 realize the mineralization and storage of CO2, achieving the dual purpose of repairing the halogenated organic pollution in groundwater and reducing the CO2 concentration in the atmosphere.

[0013] Furthermore, in step S1, the halogenated organic compound includes a combination of one or more of tribromophenol, tetrachloroethylene, hexachloroethane, trichloroethylene, dichloroethylene, chloroform, and bromoform.

[0014] Furthermore, the CO2 is captured and separated from emission sources such as the power and chemical industry, steel, cement, construction, and transportation, or from the atmosphere, and injected into groundwater in supercritical or liquid form. Supercritical and liquid CO2 are much denser than air. When the CO2 plume passes through rock, it remains in the porous spaces between rock particles, preventing CO2 from escaping from the ground.

[0015] Furthermore, according to the Fe II The injection amount and injection rate of CO2 are determined based on the concentration of CO2 and the content of halogenated organic matter. Preferably, the operating pressure and temperature during the CO2 injection process can also be optimized and adjusted in combination with factors such as geological conditions and groundwater depth.

[0016] Furthermore, in step S1, the natural minerals include one or more combinations of bornite, pyrite, and siderite.

[0017] Furthermore, the metal ions dissolved in the natural minerals also include Ca 2+ and Mg 2+ .Ca 2+ Mg 2+ Plasma can not only react with CO2 to generate corresponding carbonates, but also react with Fe III Co-precipitation is formed to generate iron carbonate ore (including siderite, ankerite, etc.), realizing the mineralization and storage of CO2.

[0018] Furthermore, in step S2, after CO2 is injected into the aquifer, a dissolution process occurs, reacting with H2O to generate H2CO3, and the reaction product H2CO3 is ionized to generate H + and CO3 2- This process releases H + , which reduces the pH value of groundwater to a weakly acidic environment of about 5.0, leading to complex water-rock interactions and dissolution and precipitation of minerals, FeCO3 particles and / or Fe-containing IIThe natural minerals release metal ions through rock-water reaction, achieving the reduction and dehalogenation of halogenated organic matter, and the generated Fe III and Ca 2+ and Mg 2 + The ions continue to react with CO2 to form stable carbonate minerals. In the short term, the CO2-water-rock interaction is mainly mineral dissolution, which promotes the reduction and dehalogenation of halogenated organic matter in the groundwater; in the long term, the CO2-water-rock interaction is mainly carbonate mineral precipitation, achieving the mineralization and storage of CO2.

[0019] Furthermore, step S2 further includes: adding divalent iron salt to the groundwater to make Fe II The concentration of the divalent iron salt is not less than 0.1 mmol / L. Preferably, the divalent iron salt comprises a combination of one or more of FeCl2, FeCO3, and FeSO4.

[0020] Furthermore, in the actual underground environment, with the fluctuation of natural environment and the interference of human activities, the underground environment will have the situation of anaerobic-aerobic alternation. When the underground anaerobic environment changes to aerobic, FeCO3 or other Fe II Minerals can activate molecular oxygen to generate •OH, which can oxidize and degrade HOCs; under aerobic conditions, Fe II It can activate molecular oxygen to generate free radicals such as hydroxyl radicals and superoxide radicals to promote the oxidative dehalogenation of HOCs.

[0021] Preferably, step S3 further comprises: introducing oxygen or air into the groundwater environment to convert the groundwater environment into an aerobic environment to improve the degradation efficiency of the halogenated organic matter.

[0022] The technical solution adopted by the present invention to achieve the second purpose is: to provide a system for enhancing the dehalogenation of halogenated organic matter in groundwater and simultaneous carbon dioxide mineralization and storage based on the method described in one of the purposes of the present invention using carbon dioxide, including: a CO2 storage device, a CO2 injection device, monitoring equipment and an analysis and processing unit.

[0023] Among them, the CO2 storage device includes several energy storage tanks for storing CO2 captured and separated from emission sources such as energy utilization, industrial processes, or the air; the CO2 injection device is used to inject the CO2 in the energy storage tank into the ground in supercritical or liquid form; the monitoring equipment includes several in-situ analysis equipment for monitoring changes in groundwater environmental hydrological parameters, the morphology of primary and secondary minerals, surface element distribution, etc., and in-situ monitoring of dehalogenation and carbon fixation; the analysis and processing unit dynamically detects the Ca content of the water sample based on the separated groundwater and mineral samples contaminated by HOCs 2+ Mg 2+ 、Fe IIParameters such as HOCs content and mineral element analysis were used to further quantify the dehalogenation and carbon fixation effects.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The method provided by the present invention for utilizing carbon dioxide to enhance the dehalogenation of halogenated organic matter in groundwater and the simultaneous mineralization and storage of carbon dioxide can not only effectively remove halogenated pollutants in groundwater, but also achieve the fixation and storage of CO2 during the remediation process, thereby achieving the synergistic effect of pollution reduction and carbon reduction, providing a new solution for groundwater remediation and climate change mitigation, and having important environmental benefits and social value.

[0026] (2) The method and system provided by the present invention for enhancing the dehalogenation of halogenated organic matter in groundwater and the simultaneous mineralization and storage of carbon dioxide are applied to the treatment process of groundwater contaminated by halogenated organic matter, and CO2 injection is used to enhance the Fe II The reduction-oxidation-dehalogenation activity of CO2 increased the remediation efficiency of HOCs-contaminated groundwater; II The synergistic effect of the FeCO3 and FeCO3 improves the stability and efficiency of CO2 storage by generating stable FeCO3 particles. This method and system achieves strong environmental and social benefits by simultaneously achieving CO2 storage and groundwater contamination remediation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A flow chart of a method for enhancing the dehalogenation of halogenated organic matter in groundwater and simultaneous mineralization and storage of carbon dioxide using carbon dioxide provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0030] The present invention will be further described below with reference to specific examples, but they are not intended to limit the present invention.

[0031] See also Figure 1 The present invention provides a method for enhancing the dehalogenation of halogenated organic matter in groundwater by using CO2. In this method, CO2 is combined with ionic Fe IICombined to form FeCO3 solid particles, the reduction, oxidation and dehalogenation of halogenated organic matter and the fixation of CO2 are achieved; on the other hand, the CO2 introduced in the form of carbonated water makes Fe II Structural Fe in minerals II dissolution, further improving the reduction and dehalogenation efficiency of organic pollutants.

[0032] Example 1

[0033] Step 1: Prepare 0.5 M Fe in an oxygen-free glove box. II solution, using 1M NaOH solution to II After the solution is adjusted to 7.0, excess CO2 is passed into the Fe II The FeCO3 suspension stock solution was formed in the solution and its Fe was measured after washing three times. II Concentration for later use;

[0034] Step 2: Use 100 mL brown blue-capped bottle as the reaction system (working system is 50 mL). First, add FeCO3 suspension to the reaction system under anaerobic conditions to make Fe II The concentration reached 10 mM, tribromophenol TBP stock solution was added to make the TBP concentration in the system reach 5 μM, and then oxygen-free ultrapure water was added to make the volume 50 mL. Then the glove box was removed and exposed to aerobic conditions, and the system was placed on a magnetic stirrer at 400 rpm for 36 h until Fe II After being fully oxidized, the removal rate of TBP can reach 28%, and the HOCs in the water body meet the target requirements for oxidation removal.

[0035] Example 2

[0036] A 100 mL brown bottle with a blue cap was used as the reaction system (the working system was 50 mL). Pyrite suspension (FeS2 purity was about 70%) was first added to the reaction system under anaerobic conditions to make its concentration reach 1 g / L. CO2 was introduced into the system until saturation, and the system was allowed to stand for 1 h under anaerobic conditions to allow Fe in the system to II Dissolve as much as possible, the pyrite suspension dissolves Fe II The concentration was about 1.5 mM. TBP stock solution was added to make the TBP concentration in the system reach 5 μM, and then oxygen-free ultrapure water was added to make the volume 50 mL. Then the glove box was removed and exposed to aerobic conditions. The system was placed on a magnetic stirrer at 400 rpm for 10 h until Fe II After being fully oxidized, the removal rate of TBP can reach 61%, and the HOCs in the water body meet the target requirements for oxidation removal.

[0037] In the above embodiment, the changes in HOCs concentration before and after the reaction and the amount of carbon fixed are shown in Table 1 below. Carbon fixed amount = (CO2 concentration after reaction - CO2 concentration before reaction) / CO2 concentration before reaction.

[0038] Table 1

[0039]

[0040] As can be seen from the above table,

[0041] By adding Fe II The method of introducing CO2 into the system is to make CO2 react with ionic Fe in the form of carbonated water. II Combined to form structural ferrous iron such as FeCO3 or adsorbed Fe on the surface of minerals II , compared to ionic Fe II The redox activity is higher, which can further enhance the reduction-oxidation dehalogenation process and simultaneously achieve the mineralization and storage of CO2.

[0042] Furthermore, compared with Example 1, which uses FeCO3 suspension and mainly relies on FeCO3 to activate molecular oxygen to generate •OH to achieve the reduction and dehalogenation of halogenated organic matter, Example 2 uses natural mineral pyrite to react with CO2 to achieve higher dehalogenation efficiency. The reason for this may be that in natural mineral pyrite, the active Fe II There are more types, including dissolved ionic FeII, adsorbed Fe on the mineral surface II , and the generated FeCO3, etc., are more complex in composition and have more active species than those in Example 1.

[0043] The present invention also provides a system for utilizing carbon dioxide to enhance the dehalogenation of halogenated organic matter in groundwater and simultaneous carbon dioxide mineralization and storage. The system comprises: a CO2 storage device, a CO2 injection device, a monitoring device, and an analysis and processing unit.

[0044] Among them, the CO2 storage device mainly captures and separates CO2 from emission sources such as energy utilization, industrial processes, or air and stores it in a storage tank; the CO2 injection device is used to inject the CO2 in the storage tank into the ground in supercritical or liquid form; the monitoring equipment includes in-situ analysis equipment, which is used to monitor changes in groundwater environmental hydrological parameters, the morphology of primary and secondary minerals, surface element distribution, etc., and in-situ monitoring of dehalogenation and carbon fixation; the analysis and processing unit dynamically detects the Ca content of water samples based on the separated groundwater and mineral samples contaminated by HOCs. 2+ Mg 2+ 、Fe II Parameters such as HOCs content and mineral element analysis were used to further quantify the dehalogenation and carbon fixation effects.

[0045] Application Example 1

[0046] In an area of ​​groundwater contaminated by tetrachloroethylene, CO2 was injected into the groundwater by building an injection well. II The dehalogenation performance is poor, and the injected CO2 and dissolved Fe II The reaction forms FeCO3 particles, and the dissolved Fe on the surface of FeCO3 particles II and structural Fe II The activity is enhanced and the reduction and dehalogenation of tetrachloroethylene is promoted. At the same time, the FeCO3 particles convert CO2 into solid iron carbonate through further mineralization reaction, achieving effective storage of CO2.

[0047] Application Example 2

[0048] In a groundwater system containing wollastonite, the H + Promotes the dissolution of wollastonite and releases a large amount of Ca 2+ and Mg 2+ ions. These ions react with CO3 in water - and HCO3 - The reaction generates a carbonate solid with high thermal stability, and the dissolved Fe II The reduction-oxidation-dehalogenation process of the pollutant chloroform in groundwater was strengthened, achieving the purpose of simultaneous carbon fixation and pollutant dehalogenation.

[0049] Application Example 3

[0050] In a groundwater system containing pyrite, the H + Promotes the dissolution of pyrite and releases a large amount of Fe II , Ca 2+ and Mg 2+ ions. Under anaerobic and aerobic conditions, Fe II Ions can react with molecular oxygen to activate molecular oxygen to generate •OH, thus achieving the oxidative degradation of tribromophenol. In the process of reduction and oxidative dehalogenation, due to the CO3 - The formation of mineral-dissolved Ca 2+ and Mg 2+ Ions can combine with it to form carbonate precipitation, thereby achieving the mineralization and storage of CO2.

[0051] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the present invention specification should be included in the protection scope of the present invention.

Claims

1. A method for enhancing the dehalogenation of halogenated organic matter in groundwater and simultaneous mineralization and storage of carbon dioxide using carbon dioxide, characterized in that: The following steps are involved: S1, containing halogenated organic matter and Fe II CO2 is injected into the groundwater; the Fe II Including dissolved Fe II and Fe present in natural minerals II ; S2, CO2 react with groundwater to form carbonated water. In the groundwater environment, carbonated water undergoes one or two of the following reactions: carbonated water reacts with dissolved Fe in groundwater. II The reaction forms FeCO3 particles, or H + Promote the Fe II dissolution; S3, FeCO3 particles and dissolved Fe on the surface of natural minerals II and structural Fe II Promote the reduction, oxidation and dehalogenation of halogenated organic matter to generate Fe III ;Fe III Under the action of CO2, it co-precipitates with mineral ions in groundwater to form iron carbonate, realizing the mineralization and storage of CO2.

2. The method according to claim 1, characterized in that In step S1, the halogenated organic compound includes one or more of tribromophenol, tetrachloroethylene, hexachloroethane, trichloroethylene, dichloroethylene, chloroform, and bromoform.

3. The method according to claim 1, characterized in that In step S1, the CO2 is captured and separated from industrial emission sources or the atmosphere, and injected into groundwater in supercritical or liquid form.

4. The method according to claim 1, wherein In step S1, according to the Fe II The injection amount and injection rate of CO2 are determined by the concentration of CO2 and the content of halogenated organic matter.

5. The method according to claim 1, wherein In step S1, the natural minerals include one or more of bornite, pyrite, and siderite.

6. The method according to claim 1, characterized in that In step S2, the metal ions dissolved in the natural minerals also include Ca 2+ and Mg 2+ .

7. The method according to claim 1, characterized in that Step S2 also includes: adding divalent iron salt to the groundwater to make Fe II The concentration is not less than 0.1mmol / L.

8. The method according to claim 7, characterized in that The divalent iron salt includes one or more combinations of FeCl2, FeCO3, and FeSO4.

9. The method according to claim 1, characterized in that Step S3 also includes: introducing oxygen or air into the groundwater environment to transform the groundwater environment into an aerobic environment.

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