A method for removing humic acid from water

Abstract

This invention relates to the field of water treatment technology, and in particular to a method for removing humic acid from water. The method includes the following steps: adding activated carbon to water containing humic acid, simultaneously introducing carbon dioxide into the water, reacting, and thus removing the humic acid from the water. This invention provides an innovative way to utilize carbon dioxide and biochar, contributing to carbon reduction and pollution control. The method of this invention reduces the use of chemical agents in the humic acid treatment process, lowering the risk of secondary pollution. The method of this invention simplifies the equipment system and operation process for humic acid treatment, reducing initial investment and operating costs. The method of this invention has advantages such as simple operation, good economy, and high humic acid removal rate, and can be combined with technologies such as biochar preparation and carbon dioxide capture and utilization, showing application potential in multiple fields such as water treatment, biomass utilization, and carbon dioxide replenishment.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a method for removing humic acid from water. Background Technology

[0002] Human survival and development inevitably generate large amounts of wastewater. This wastewater contains nutrients, sediments, industrial wastewater, and organic and inorganic pollutants such as heavy metals. Humic acid is a typical recalcitrant natural organic compound in wastewater, possessing a supramolecular structure and no fixed molecular formula. It is mainly found in various wastewaters, including natural water, landfill leachate, domestic sewage, livestock and poultry manure wastewater, and toilet wastewater. Humic acid contains functional groups such as carboxyl, methoxy, and hydroxyl groups, which can negatively impact wastewater treatment through mechanisms such as complexing heavy metals and adsorbing other pollutants. Therefore, research on the removal of humic acid from wastewater is crucial.

[0003] Currently, various technologies are available for the removal of humic acid from wastewater, the most common of which include physical, chemical, and biological methods.

[0004] Physical methods mainly include filtration, adsorption, and ion exchange. Filtration uses filter media with different pore sizes to intercept humic acid particles from the water, which is economical, but this method has limited effectiveness in treating dissolved humic acid. Adsorption and ion exchange use specific adsorbents or resins to adsorb or exchange humic acid into the water. The processes are simple, but their capacity is limited, requiring regular replacement or regeneration, which increases operating costs.

[0005] Chemical methods mainly involve reacting humic acid with oxidants, reducing agents, or precipitants to convert it into easily precipitable or easily degradable substances, thereby achieving the effect of humic acid removal. This method has the strongest removal capacity for humic acid. However, chemical methods usually require a high dosage of chemical reagents, and the byproducts may cause secondary pollution to the aquatic environment.

[0006] Biological methods utilize microorganisms to degrade humic acid, making them environmentally friendly. However, these methods are significantly affected by environmental factors such as temperature and pH, have long processing cycles, and low humic acid removal efficiency.

[0007] In summary, existing technologies have certain advantages in removing humic acid from wastewater, but they still have problems such as limited applicability, easy generation of byproducts and secondary pollutants, high operating costs, great susceptibility to environmental factors, and low removal efficiency.

[0008] Therefore, this invention aims to develop a novel method for removing humic acid from wastewater, integrating multiple advantages such as high removal efficiency, low cost, few byproducts, and wide applicability into a single technology. Summary of the Invention

[0009] To address the problems existing in the removal of humic acid from water in current technologies, this invention provides a method for removing humic acid from water. This invention utilizes a combination of activated carbon and carbon dioxide to treat humic acid in water, achieving highly efficient removal under normal temperature and pressure conditions. This provides a comprehensive, efficient, and sustainable solution to the problem of humic acid removal in water.

[0010] To achieve the above objectives, the present invention provides the following solution:

[0011] One of the technical solutions of this invention is a method for removing humic acid from water, comprising the following steps:

[0012] Activated carbon is added to water, and carbon dioxide is simultaneously introduced into the water to react and remove humic acid from the water.

[0013] The second technical solution of the present invention is a method for simultaneously improving the conversion rate of humic acid and the removal rate of chemical oxygen demand in water, which adopts the above-mentioned method for removing humic acid in water.

[0014] The present invention discloses the following technical effects:

[0015] This invention provides an innovative approach to utilizing carbon dioxide and biochar, contributing to carbon reduction and pollution control. The method of this invention reduces the use of chemical agents in the humic acid treatment process, thereby lowering the risk of secondary pollution.

[0016] The method of this invention simplifies the equipment system and operation process for humic acid treatment, and reduces initial investment and operating costs.

[0017] The method of this invention has the advantages of simple operation, good economy and high humic acid removal rate. It can be combined with technologies such as biochar preparation and carbon dioxide capture and utilization, and shows application potential in multiple fields such as water treatment, biomass utilization and carbon dioxide replenishment. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the apparatus used in the method for removing humic acid from water according to the present invention; in the figure, a carbon dioxide storage cylinder is connected to a sealed reactor via a pipeline, and an exhaust port is provided on the sealed reactor; a magnetic stirrer is provided below the sealed reactor. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] The first aspect of this invention provides a method for removing humic acid from water, comprising the following steps:

[0026] Activated carbon is added to water, and carbon dioxide is simultaneously introduced into the water to react and remove humic acid from the water.

[0027] In a preferred embodiment of the present invention, the mass ratio of humic acid to activated carbon in the water is 1:5 to 100. More preferably, it is 1:5 to 50; even more preferably, it is 1:5 to 30.

[0028] In a preferred embodiment of the present invention, when the concentration of humic acid in the water is 0-30 mg / L, the amount of activated carbon added to the water is 0-0.3 g / L; when the concentration of humic acid in the water is 30-300 mg / L, the amount of activated carbon added to the water is 0.15-6 g / L; and when the concentration of humic acid in the water is 300-3000 mg / L, the amount of activated carbon added to the water is 1.5-30 g / L.

[0029] The mass ratio of humic acid to activated carbon in water, as well as the amount of activated carbon added, are related to the concentration of humic acid in the water. For example, when the concentration of humic acid in water is 2000 mg / L, an addition of 20 g / L of activated carbon is more effective in removing humic acid from the water. When the concentration of humic acid in water is 200 mg / L, an addition of 6 g / L of activated carbon is more effective in removing humic acid from the water.

[0030] In a preferred embodiment of the present invention, the rate at which carbon dioxide is introduced into the water is 0.1 to 10 L / min. Preferably, it is 1 L / min.

[0031] As the concentration of humic acid in the water changes, the flow rate of carbon dioxide also needs to be changed. The higher the concentration of humic acid, the higher the required flow rate of carbon dioxide. Therefore, the preferred limit of the carbon dioxide flow rate in this invention is 0.1 to 10 L / min.

[0032] In a preferred embodiment of the present invention, the reaction time is 30-90 minutes, preferably 60 minutes.

[0033] As the reaction time increases, the humic acid conversion rate and chemical oxygen demand removal rate improve. However, when the reaction time increases to a certain extent, the effect of extending the reaction time on improving the humic acid conversion rate and chemical oxygen demand removal rate becomes less significant. Therefore, the preferred reaction time of this invention is 30-90 min.

[0034] In a preferred embodiment of the present invention, the reaction is carried out under stirring conditions.

[0035] In a preferred embodiment of the present invention, the stirring rate is 200-400 rpm. Preferably, it is 300 rpm.

[0036] As the stirring rate increases, the humic acid conversion rate and the chemical oxygen demand removal rate improve. However, when the stirring rate increases to a certain extent, the effect of increasing the stirring rate on improving the humic acid conversion rate and the chemical oxygen demand removal rate becomes less significant. Therefore, the preferred stirring rate of this invention is 200-400 rpm.

[0037] In a preferred embodiment of the present invention, the reaction is carried out in a closed reactor at 5-30°C and 0.1-0.15 MPa; more preferably, the reaction is carried out at room temperature of 20°C and atmospheric pressure of 0.1 MPa.

[0038] In this invention, carbon dioxide is discharged through an exhaust port after being stirred and reacted with water containing humic acid and activated carbon.

[0039] A second aspect of the present invention provides a method for simultaneously improving the conversion rate of humic acid and the removal rate of chemical oxygen demand in water, using the above-mentioned method for removing humic acid from water.

[0040] A schematic diagram of the apparatus used in the method for removing humic acid from water according to the present invention is shown below. Figure 1 As shown in the figure, a carbon dioxide storage cylinder is connected to a sealed reactor via a pipeline, and the sealed reactor is equipped with an exhaust port. A magnetic stirrer is installed below the sealed reactor.

[0041] The specific surface area of ​​the activated carbon used in the embodiments and comparative examples of this invention is 645.9626 m². 2 / g, pore volume is 0.203084cc / g.

[0042] The technical solution of the present invention will be further illustrated by the following embodiments.

[0043] Figure 1 This is a schematic diagram of the apparatus used in the method for removing humic acid from water according to the present invention; in the figure, a carbon dioxide storage cylinder is connected to a sealed reactor via a pipeline, and an exhaust port is provided on the sealed reactor; a magnetic stirrer is provided below the sealed reactor.

[0044] Example 1

[0045] Synergistic removal of humic acid by carbon dioxide and activated carbon under ambient temperature and pressure differential:

[0046] At 20℃ and 0.1MPa, 50mL of a 2000mg / L humic acid solution and 1g of activated carbon were added to a closed reactor. Simultaneously, carbon dioxide was introduced at a flow rate of 1L / min until the solution was below the liquid surface (i.e., the reaction atmosphere was carbon dioxide). The reaction was carried out at 300rpm for 60min. (The carbon dioxide, humic acid solution, and activated carbon were stirred and then discharged through the exhaust port.)

[0047] Example 2

[0048] Synergistic removal of humic acid by carbon dioxide and activated carbon under ambient temperature and pressure differential:

[0049] Compared with Example 1, the only difference is that the concentration of humic acid and the amount of activated carbon added are reduced by a factor of ten; that is, the concentration of humic acid solution is 200 mg / L and the amount of activated carbon added is 0.1 g.

[0050] Example 3

[0051] Synergistic removal of humic acid by carbon dioxide and activated carbon under ambient temperature and pressure differential:

[0052] The only difference from Example 2 is that the amount of activated carbon added is 0.3g.

[0053] Comparative Example 1

[0054] The only difference from Example 1 is that carbon dioxide is replaced with nitrogen (i.e., the reaction atmosphere is a nitrogen atmosphere).

[0055] Comparative Example 2

[0056] The only difference from Example 1 is that activated carbon is not added to the reactor (i.e., the addition of activated carbon is omitted).

[0057] Comparative Example 3

[0058] The only difference from Example 1 is that the reaction is carried out without stirring.

[0059] Test case

[0060] 1. Treatment effect

[0061] The conversion rate of humic acid and the chemical oxygen demand in the aqueous phase after treatment in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1.

[0062] The concentration of humic acid was detected using a UV-Vis spectrophotometer, and the conversion rate was calculated by the ratio of the initial concentration to the post-reaction concentration. Chemical oxygen demand (COD) was detected using a COD analyzer, and the removal rate was calculated by the ratio of the initial COD to the post-reaction COD.

[0063] Table 1

[0064]

[0065] Table 1 shows that, based on the results of Examples 1-3, when the ratio of humic acid concentration to activated carbon addition remains constant, a decrease in humic acid concentration leads to a decrease in humic acid conversion rate and chemical oxygen demand removal rate. Conversely, when the humic acid concentration decreases, an increase in the ratio of humic acid concentration to activated carbon addition promotes an increase in humic acid conversion rate and chemical oxygen demand removal rate. This indicates that increasing the ratio of humic acid concentration to activated carbon addition is beneficial for removing lower concentrations of humic acid.

[0066] Table 1 shows that the synergistic effect of carbon dioxide atmosphere and activated carbon leads to a high conversion rate of humic acid and a high removal rate of chemical oxygen demand.

[0067] Table 1 shows that the comparison of data between Comparative Example 3 and Example 1 indicates that stirring allows activated carbon to come into full contact with carbon dioxide, thereby promoting the removal of humic acid.

[0068] 2. Characterization of activated carbon before and after the reaction

[0069] Table 2

[0070]

[0071] Table 2 shows the nitrogen adsorption-desorption data of activated carbon before reaction, and activated carbon after reaction (60 min) in Comparative Example 1 and Example 1. It can be seen that nitrogen atmosphere leads to a significant decrease in the specific surface area and pore volume of activated carbon, indicating that humic acid is adsorbed in the pores of activated carbon. In contrast, activated carbon under carbon dioxide atmosphere increases the specific surface area and decreases the pore volume less, indicating that carbon dioxide can partially inhibit the adsorption of humic acid in the pores of activated carbon.

[0072] This invention is the first to propose a method for removing humic acid from water by the synergistic effect of carbon dioxide atmosphere and activated carbon under normal temperature and pressure conditions. This method achieves efficient removal of humic acid from water, is economical, and is suitable for treating humic acid wastewater with different concentration ranges.

[0073] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for removing humic acid in water, characterized by, The method comprises the following steps: adding activated carbon into water containing humic acid, and introducing carbon dioxide into the water, and reacting to remove humic acid in the water; the mass ratio of humic acid in water to activated carbon is 1:5-100; when the concentration of humic acid in water is 30-300 mg / L, the amount of activated carbon added in water is 0.15-6 g / L; when the concentration of humic acid in water is 300-3000 mg / L, the amount of activated carbon added in water is 1.5-30 g / L; the rate of introducing carbon dioxide into water is 0.1-10 L / min; the reaction is carried out under stirring; the reaction is carried out in a closed reactor under the conditions of 5-30 ℃, 0.1-0.15 MPa; after the carbon dioxide is stirred with the water containing humic acid and activated carbon, it is discharged through the exhaust port.

2. The method of removing humic acid in water according to claim 1, characterized by, the reaction time is 30-90 min.

3. The method of removing humic acid in water according to claim 1, characterized by, the stirring rate is 200-400 rpm.

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