A method for degrading halogenated organic pollutants using reduced humic acid
By activating molecular oxygen oxidation of halogenated organic pollutants in reducing humic acid (HAred), the problems of low efficiency and high cost of halogenated organic pollutants in groundwater in the prior art are solved, and low-cost and efficient pollutant degradation effect is achieved.
Patent Information
- Application Number
- CN202310002238.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-01-03
- Publication Date
- 2025-08-19
- Estimated Expiration
- 2043-01-03
AI Technical Summary
The prior art is difficult to efficiently and at low cost to remove halogenated organic pollutants in groundwater, especially HOCs, and chemical oxidation methods are costly in large-scale applications. How to effectively reduce the cost of agents and maximize the degradation of pollutants is the focus of attention in the environmental field.
Humic acid is reduced to reduced humic acid (HAred) under ferrous, sodium disulfate or electrochemical action, and activated molecular oxygen production·OH under aerobic conditions to achieve oxidative dehalogenation of halogenated organic pollutants.
It has achieved efficient removal of halogenated organic pollutants under low-cost conditions and reduced the risk of secondary pollution, providing new ideas for groundwater restoration, and has green and economic benefits.
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Figure CN115959742B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of application of in-situ chemical remediation technology for groundwater, and in particular to a method for degrading halogenated organic pollutants using reduced humic acid. Background Art
[0002] With the rapid development of my country's industry, the concentration of halogenated organic contaminants (HOCs) in drinking water sources has gradually increased. These HOCs primarily include fluorinated, chlorinated, and brominated organic compounds. HOCs are highly toxic, structurally stable, highly mobile, and difficult to biodegrade. They pose a significant threat to aquatic environments and drinking water safety, making them a highly hazardous class of substances. Consequently, numerous environmental researchers worldwide are dedicated to finding efficient methods for treating HOCs in drinking water, including physical methods (such as gas stripping, adsorption, and extraction), biological methods (such as aerobic and anaerobic methods), and chemical methods (such as oxidation and reduction). Physical methods are simple and easy to operate, but they cannot completely dehalogenate and degrade pollutants. Biological methods are often limited to laboratory scale and are generally inefficient. Chemical methods, which utilize oxidizing / reducing agents to dehalogenate HOCs, offer advantages such as high efficiency and effectiveness, and have been extensively studied in wastewater treatment in recent years. Chemical reduction methods use strong reducing reactions to completely or selectively remove the heteroatoms that make HOCs difficult to degrade. However, this technology has problems such as high energy consumption and strict requirements on the reactor. Oxidation methods are divided into direct oxidation and advanced oxidation methods. Direct oxidation is limited by the oxidation potential of the oxidant, and its degradation efficiency of HOCs is relatively low. Advanced oxidation technology can produce active substances such as free radicals with strong oxidizing properties through methods such as light, electricity, ozone, and Fenton, thereby achieving rapid and efficient removal of pollutants. It has received widespread attention in recent years. However, the commonly used oxidant materials are relatively expensive and difficult to be sustainable in large-scale industrial applications. How to effectively reduce the cost of reagents while maximizing the degradation of pollutants has always been a focus of attention in the environmental field.
[0003] Humic acid (HA) is a natural soil substance that exists in almost all terrestrial and aquatic environments. It is a polymeric and polydisperse organic compound. It has redox activity. The most important redox active part in the HA molecule is the functional group, such as sulfonyl or phenolic group, especially quinone group. In addition, HA can be reduced by microorganisms, ferrous iron, etc. to form reduced humic acid (HA red ), and electrons can be red transfer to other regions with higher redox potential (E h ) electron acceptors, such as Fe(III) minerals, oxygen molecules, etc., and HA is cheap and easy to obtain in nature. redThe oxidative activity under aerobic conditions promotes the degradation of HOCs, which can greatly reduce the cost of reagents, has potential application value, and can provide new ideas for current groundwater remediation work. Summary of the Invention
[0004] In view of this, the present application provides a method for removing halogenated organic pollutants in water by using reduced humic acid, which uses ferrous iron, sodium dithionate, electrochemistry, etc. to reduce HA to form HAred, and then HA red Activated molecular oxygen produces ·OH with strong oxidizing effect, which causes HOCs in water to be oxidized and dehalogenated, thereby achieving efficient removal of halogenated organic matter in water at low reagent cost.
[0005] The present application provides a method for degrading halogenated organic pollutants using reduced humic acid, comprising the following steps:
[0006] Reduce humic acid to reduced humic acid HA red ;
[0007] The Hared is used to degrade halogenated organic pollutants under aerobic conditions.
[0008] Suitably, but not limitingly, the reduction of humic acid to reduced humic acid HAred is carried out under the condition of adding a reducing agent.
[0009] Suitably, but not limiting, the reducing agent is a ferrous salt and / or a dithionite salt.
[0010] Suitable but not limiting, the reducing agent is added while adjusting the acid-base environment of the system to be alkaline.
[0011] Suitably but not restrictively, the reduction of humic acid to reduced humic acid HAred is carried out under the condition of cathode electric reduction.
[0012] Suitable but not limiting, the acid-base environment of the system is adjusted to be alkaline while the cathode is electrically reduced.
[0013] Suitably, but not limiting, the Fe(II) concentration in the ferrous solution is not less than 50 mM.
[0014] Suitably, but not limitatively, the halogenated organic pollutant is at least one of pentachlorophenol, hexachlorocyclohexane, chloroform, o-dichlorobenzene, trichloroethylene, dichloroethylene, carbon tetrachloride and tribromophenol.
[0015] As an exemplary but not limiting example, the operation process of the method of the present application includes the following steps:
[0016] (1) Natural humic acid solid was added to ultrapure water and the pH was adjusted to 11.0 to completely dissolve HA to prepare HA stock solution. The solution was then neutralized to pH 7.5 and placed in an anaerobic glove box (4% H2 and 96% N2, COY, USA) in the dark and stirred for 48 h before use.
[0017] (2) Prepare an electrolyte containing 1 M KCl, 0.5 M ferrous solution, and sodium dithionate solution in an oxygen-free glove box and set aside;
[0018] (3) Use a 100ml blue-capped bottle or electrolytic cell as the reaction system (the working system is 50ml), add HA stock solution into the reaction system, then add reducing agent or turn on the power to stir and reduce HA for 1h, and then reduce HA red The solution was transferred to a new 100 ml blue-cap bottle, HOCs were added to the system, and the pH was adjusted to neutral. The solution was then removed from the glove box and stirred at 400 rpm using a magnetic stirrer.
[0019] Compared with the prior art, this application has the following beneficial effects:
[0020] 1. This method can fully utilize the abundant HA in the natural environment and, combined with chemical reduction methods, has potential application value. Utilizing HAred's reducing ability and its ability to undergo multiple reduction-oxidation cycles, a HAred system can be constructed to remove HOCs from (underground) contaminated water bodies, achieving chemical remediation of contaminated water bodies and reducing the risk of secondary pollution. This method can provide new ideas for the treatment of HOCs-contaminated water bodies.
[0021] 2. The method of this application utilizes the reduction system formed by HAred to gradually and completely dehalogenate HOCs under aerobic conditions, with low-cost, green and efficient removal capabilities;
[0022] 3. This application method is simple, convenient, easy to implement and cost-saving. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.
[0024] Figure 1 The embodiment of this application provides a method using HA red Schematic diagram of the structure of the reduction system for groundwater remediation principle diagram. DETAILED DESCRIPTION
[0025] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.
[0026] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.
[0027] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.
[0028] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.
[0029] See also Figure 1 The present invention uses ferrous iron, sodium dithionite, electrochemistry, etc. to reduce HA to form HA red system, HA red It provides electrons to oxygen molecules in the reaction system and continuously reduces oxygen molecules to generate active oxygen species OH, which acts on the dehalogenation and removal of HOCs in water.
[0030] Example 1:
[0031] In this embodiment, a method for removing HOCs from water by reducing HA with ferrous iron is used to treat water contaminated with tribromophenol, where the concentration of tribromophenol is 5 μM, and comprises the following steps:
[0032] 0.5 g of natural humic acid solid was dissolved in 100 ml of ultrapure water to prepare a 5 g / L HA stock solution. The pH of the humic acid solution was adjusted to 11.0 with alkaline solution. After the HA was completely dissolved, it was neutralized with hydrochloric acid solution to a pH of 7.5. The solution was moved to an anaerobic glove box (4% H2 and 96% N2, COY, USA) in the dark and stirred for 48 h. The carbon content was measured using a TOC instrument and set aside.
[0033] Prepare 0.5 M Fe in an oxygen-free glove box 2+ Solution and alkali solution (NaOH). Add 40ml of deoxygenated ultrapure water to a 100ml reaction bottle, adjust the pH of the solution to 8 with alkali solution (NaOH), and then add 2ml of Fe 2+ , readjust the pH to 8, add HA stock solution to ensure that the HA concentration in the system is not less than 160mg C / L, and finally add oxygen-free water to make the reaction volume 50ml, place it on a magnetic stirrer, adjust the speed to 400rpm, react for 1h, and filter;
[0034] Take 50 ml of the filtrate, add tribromophenol to make the concentration of tribromophenol in the system reach 5 μM, move out of the glove box, place on a magnetic stirrer, adjust the speed to 400 rpm, react for 6 hours, re-aerate and deoxygenate, move back to the glove box, and use Fe 2+ After reducing HA, the mixture was removed from the glove box and placed back on a magnetic stirrer at 400 rpm for 6 hours. After repeating this process five times, the removal rate of tribromophenol reached 100%.
[0035] The method in this case can make full use of the abundant humic acid substances in nature and its ability to be reduced and oxidized multiple times. It has potential application value in combination with chemical reduction and oxidation remediation methods. It constructs a ferrous-humic acid system and utilizes the rich ferrous content in the underground environment and its ability to reduce humic acid to remove tribromophenol in groundwater, realize in-situ chemical remediation and autonomous remediation of groundwater, reduce the risk of secondary pollution from exogenous inputs, and has good environmental and economic benefits.
[0036] Example 2:
[0037] This embodiment is basically the same as the first embodiment, with the following special features:
[0038] In this embodiment, a method for removing HOCs from water by reducing HA with sodium dithionite is used to treat water contaminated with tribromophenol, where the concentration of tribromophenol is 5 μM, comprising the following steps:
[0039] 0.5 g of natural humic acid solid was dissolved in 100 ml of ultrapure water to prepare a 5 g / L HA stock solution. The pH of the humic acid solution was adjusted to 11.0 with alkaline solution. After the HA was completely dissolved, it was neutralized with hydrochloric acid solution to a pH of 7.5. The solution was moved to an anaerobic glove box (4% H2 and 96% N2, COY, USA) in the dark and stirred for 48 h. The carbon content was measured using a TOC instrument and set aside.
[0040] Prepare sodium dithionite solution and alkali solution (NaOH) in an oxygen-free glove box. Add 40 ml of deoxygenated ultrapure water to a 100 ml reaction flask. Adjust the pH of the solution to 8 with alkali solution (NaOH). Add sodium dithionite solution to the reaction system and readjust the pH to 8. Add HA stock solution to ensure that the HA concentration in the system is not less than 160 mg C / L. Finally, add oxygen-free water to bring the reaction volume to 50 ml. Place the reaction on a magnetic stirrer at 400 rpm. After reacting for 1 hour, filter with suction.
[0041] Take 50 ml of the filtrate and add tribromophenol to a concentration of 5 μM. Remove the filtrate from the glove box and place it on a magnetic stirrer at 400 rpm. After 6 hours of reaction, re-aerate and deoxygenate the mixture. Return the mixture to the glove box and reduce HA again with sodium dithionite. Remove the mixture from the glove box and place it on a magnetic stirrer at 400 rpm for another 6 hours. Repeat this process five times to achieve 100% tribromophenol removal.
[0042] The method in this case can make full use of the abundant humic acid substances in nature and its ability to be reduced and oxidized multiple times. It has potential application value in combination with chemical reduction remediation methods. It constructs a sodium dithionite-humic acid system and uses the ability of sodium dithionite to reduce humic acid to remove tribromophenol in contaminated water, thereby achieving chemical remediation and autonomous remediation of contaminated water, reducing the risk of secondary pollution, and having good environmental and economic benefits.
[0043] Example 3:
[0044] This embodiment is basically the same as the first embodiment, with the following special features:
[0045] In this embodiment, a method for removing HOCs from water by electrochemically reducing HA to treat water contaminated with tribromophenol at a concentration of 5 μM comprises the following steps:
[0046] 0.5 g of natural humic acid solid was dissolved in 100 ml of ultrapure water to prepare a 5 g / L HA stock solution. The pH of the humic acid solution was adjusted to 11.0 with alkaline solution. After the HA was completely dissolved, it was neutralized with hydrochloric acid solution to a pH of 7.5. The solution was moved to an anaerobic glove box (4% H2 and 96% N2, COY, USA) in the dark and stirred for 48 h. The carbon content was measured using a TOC instrument and set aside.
[0047] Prepare 3M KCl solution and alkaline solution (NaOH) in an oxygen-free glove box. Add 40ml of deoxygenated ultrapure water to the electrolytic cell and adjust the solution pH to 8 with alkaline solution (NaOH). Add 5ml of the prepared KCl solution to the reaction system. Add HA stock solution to ensure that the HA concentration in the system is not less than 160mg C / L. Finally, add oxygen-free water to bring the reaction volume to 50ml. Place the reaction at the cathode, connect the power supply, and adjust the speed to 400rpm. After 1h of reaction, disconnect the power supply and transfer the reduced HA solution to a 100ml reaction bottle.
[0048] Tribromophenol was added to the reaction flask to a concentration of 5 μM. The flask was removed from the glove box and placed on a magnetic stirrer at 400 rpm. After 6 hours of reaction, the mixture was aerated and deoxygenated again. The flask was then returned to the glove box and electroreduced with HA again. The flask was removed from the glove box and placed on a magnetic stirrer at 400 rpm for another 6 hours. After repeating this process five times, 100% tribromophenol removal was achieved.
[0049] The method in this case can make full use of the abundant humic acid substances in nature and its ability to be reduced and oxidized multiple times. It has potential application value in combination with the electrochemical reduction remediation method. It constructs an electric-humic acid system, utilizes the humic acid substances rich in the environment, and uses low power consumption to reduce and remove tribromophenol in groundwater, realizing in-situ chemical remediation and autonomous remediation of groundwater, reducing the risk of secondary pollution from exogenous input, and has good environmental and economic benefits.
[0050] The above is only a preferred specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection of the present application.
Claims
1. A method for degrading halogenated organic pollutants using reduced humic acid, characterized in that: The following steps are involved: (1) Prepare humic acid solution under anaerobic and light-proof conditions; (2) Prepare dithionate solution under anaerobic conditions, adjust the pH to 8, add humic acid solution, stir, and filter; (3) adding halogenated organic pollutants to the filtrate and degrading the halogenated organic pollutants under aerobic conditions; (4) After the reaction in step (3) is completed, dithionate is added to the system again under anaerobic conditions to reduce humic acid, and then the halogenated organic pollutants are degraded under aerobic conditions, and this is repeated 5 times; The halogenated organic pollutant is at least one organic substance selected from the group consisting of pentachlorophenol, hexachlorocyclohexane, chloroform, o-dichlorobenzene, trichloroethylene, dichloroethylene, carbon tetrachloride and tribromophenol.