A cobalt-doped composition and its use in degrading organic pollutants

Abstract

The application discloses a cobalt-doped composition and application thereof in degradation of organic pollutants, and belongs to the technical field of organic contaminated wastewater treatment. The cobalt-doped composition has an effective component of biomass doped with cobalt on the surface and a peroxoacetic acid solution, the biomass doped with cobalt on the surface is obtained through a high-temperature molten salt method, and the effective component of the peroxoacetic acid solution is peroxoacetic acid and hydrogen peroxide. The composition can efficiently degrade organic pollutants in wastewater, has the advantages of high efficiency, good stability, wide pH application range, no influence of environmental matrix, and the like, and has a wide application prospect in treatment of organic pollutants.

Description

Technical Field

[0001] This invention belongs to the field of organic wastewater treatment technology, and more specifically, relates to a cobalt-doped composition and its application in the degradation of organic pollutants. Background Technology

[0002] Advanced oxidation techniques utilize oxidizing free radicals (such as...) · OH, SO4 ·- CH3C(O)O · Advanced oxidation technology utilizes the strong oxidizing properties of hydroxyl radicals to oxidize and degrade organic pollutants into low-toxicity small-molecule organic compounds, ultimately mineralizing them into CO2 and H2O. This chemical oxidation technology effectively removes organic pollution from soil and aquatic environments, offering advantages such as short remediation cycles and rapid economic benefits. · OH) and sulfate radicals (SO4) ·- Advanced oxidation technologies have been extensively developed and applied, but they are greatly affected by environmental substrates (such as inorganic anions and organic matter). Inorganic anions in the environment, such as chloride ions, nitrates, and carbonates, as well as organic matter, can compete with pollutants. · OH or SO4 ·- This reduces the effectiveness of advanced oxidation technologies and may even halt the oxidative degradation of organic pollutants. Furthermore, chloride ions and nitrates react with free radicals to generate corresponding free radicals (Cl...). · With NO3 · These free radicals can react with organic matter or pollutants to produce highly toxic chlorinated or nitro-substituted byproducts, posing certain ecological risks.

[0003] Take CH3C(O)O · (E 0 =2.20V, peroxyacyl radical) is a basic component of various advanced oxidation techniques. These techniques exhibit high oxidative activity, are less affected by the environmental matrix, and significantly suppress the formation of byproducts during the oxidation process. CH3C(O)O can be generated by activating peracetic acid (CH3C(O)OOH). · Examples of catalytic techniques include thermal activation, ultraviolet (UV) light activation, transition metal ion activation, and other heterogeneous catalysis methods. Some techniques for activating peracetic acid have drawbacks in practical applications; for example, thermal activation and UV light activation require significant energy consumption, and UV light activation is less effective for opaque systems. Transition metal ion activation of peracetic acid generates peroxyacyl radicals efficiently, but it also has some limitations in application. For instance, while ferrous ions can effectively activate peracetic acid to degrade pollutants, the presence of Fe in the reaction system... 2+ Competing with the target pollutant, it consumes a large number of free radicals, generating non-catalytically inactive Fe. 3+ This leads to Fe 2+The effective utilization rate of Fe decreases; more importantly, during the reaction process, as Fe... 3+ The formation of ferrous peracetic acid produces a large amount of iron sludge, and the subsequent treatment of this iron sludge not only increases processing costs but also causes solid waste pollution to the environment. To overcome the many shortcomings of the ferrous-catalyzed peracetic acid reaction system, many researchers have used complexing agents (such as piperidine carboxylic acid) to complex iron ions and control the Fe content in the solution. 2+ While complexing agents can improve the effectiveness of pollutant degradation, they also compete with pollutants for free radicals, leading to a decrease in the effective utilization rate of the target pollutant per unit of free radical. Furthermore, various metal ions, such as Co... 2+ Ru 2+ Persulfate catalysts can also efficiently activate peracetic acid to generate free radicals for the oxidation and removal of pollutants; however, these metal ions are highly toxic and pose a risk of secondary pollution. Therefore, there is an urgent need to develop environmentally friendly, efficient, and inexpensive persulfate catalysts. Summary of the Invention

[0004] 1. The problem to be solved

[0005] To address the problems of existing advanced oxidation technologies being highly susceptible to environmental matrix composition, easily generating toxic and harmful byproducts, and having low treatment efficiency, this invention provides a cobalt-doped composition and its application in the degradation of organic pollutants. This invention obtains a biomass formulation with surface-doped cobalt using a high-temperature molten salt method. The cobalt doping on the biomass surface rapidly activates peracetic acid, generating highly oxidizing peroxyacyl radicals and peroxyalkyl radicals, thus rapidly degrading organic pollutants. The cobalt-doped composition of this invention exhibits advantages such as high efficiency, good stability, a wide effective pH range, and insensitivity to environmental matrix influences during pollutant degradation.

[0006] 2. Technical Solution

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] The present invention discloses a cobalt-doped composition comprising a cobalt-doped biomass preparation and a peracetic acid preparation, wherein the cobalt-doped biomass preparation is a shellfish biomass with cobalt doped on its surface, and the effective components of the peracetic acid preparation are peracetic acid and hydrogen peroxide.

[0009] Preferably, the molar ratio between the cobalt-doped biomass preparation and the peracetic acid preparation is 0.25-0.5.

[0010] Preferably, the peracetic acid preparation is a peracetic acid solution containing hydrogen peroxide, peracetic acid, and sulfuric acid in a molar ratio of 3:2:0.5.

[0011] More preferably, the peracetic acid solution is obtained by reacting hydrogen peroxide and pure acetic acid under acidic conditions for more than 24 hours, wherein the molar ratio of hydrogen peroxide, acetic acid and sulfuric acid is 3:2:0.5, and physical stirring is performed during the reaction.

[0012] Preferably, the cobalt-doped biomass preparation is prepared by a high-temperature molten salt method. The specific process is as follows: shellfish shell powder is mixed with alkali metal hydroxide, ground, and then subjected to a first high-temperature treatment. After treatment, the mixture is cooled, washed, and dried to obtain a solid powder. Then, the solid powder is mixed with potassium chloride, lithium chloride, and cobalt chloride, ground, and then subjected to a second high-temperature treatment. After treatment, the mixture is cooled, washed, and dried to obtain the cobalt-doped biomass preparation.

[0013] Preferably, the mass ratio of the shellfish shell powder to the alkali metal hydroxide is 2:1, wherein the shellfish shell is an oyster shell and the alkali metal hydroxide is potassium hydroxide.

[0014] Preferably, the material ratio of the solid powder obtained after the first high-temperature treatment to potassium chloride, lithium chloride, and cobalt chloride is set as follows: under the condition of 2g of solid powder, the amounts of potassium chloride, lithium chloride, and cobalt chloride are 10mM, 10mM, and xmM, respectively, where x = 0.5, 1, 2, or 4.

[0015] Preferably, the specific process of the first high-temperature treatment and the second high-temperature treatment is as follows: starting from room temperature, the temperature is increased at a rate of 5℃ / min, and after the temperature reaches 200℃, it is held for 30 minutes. Then, the temperature is increased at a rate of 5℃ / min to 500℃ and held for 4 hours. After calcination, the temperature is naturally annealed and cooled.

[0016] Preferably, the drying is oven drying or freeze drying, wherein the oven drying temperature is 75°C, and the freeze drying conditions are a pressure of 1 mbar and a temperature of -40°C.

[0017] Preferably, the first high-temperature treatment and the second high-temperature treatment are carried out in a nitrogen atmosphere or in the absence of air.

[0018] The application of a cobalt-doped composition of the present invention in the degradation of organic pollutants includes adding the cobalt-doped composition to wastewater containing organic pollutants to obtain a mixed solution, mixing and reacting for 2-10 minutes, and then separating and recovering the mixed solution after reaction, wherein the organic pollutant is ciprofloxacin or a quinolone antibiotic.

[0019] Preferably, the concentration of the cobalt-doped biomass preparation in the mixture solution is 0.1-0.5 g / L, and the concentration of the peracetic acid preparation is 0.2-2.0 mM.

[0020] Preferably, the wastewater further contains chloride ion concentration of 17.5-177.5 mg / L, nitrate concentration of 31-310 mg / L, carbonate concentration of 30.5-305.0 mg / L, or organic carbon concentration of 10-50 mg / L.

[0021] Preferably, the pH of the reaction system is 3-11.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) A cobalt-doped composition of the present invention comprises a cobalt-doped biomass preparation and a peracetic acid preparation. The cobalt-doped biomass preparation is based on biomass obtained from oyster shell powder as raw material and is obtained by cobalt doping through a high-temperature molten salt method. The cobalt doped on the surface of the biomass can rapidly activate the peracetic acid in the peracetic acid preparation to generate peroxyacyl free radicals and peroxyalkyl free radicals with strong oxidizing power, thereby rapidly degrading organic pollutants.

[0025] (2) A cobalt-doped composition of the present invention uses the shells of shellfish that are abundant in nature as raw materials to prepare cobalt-doped biomass activated peracetic acid. Shellfish shells are a type of biomass that are abundant in nature and are very easy to obtain. The subsequent processing steps are simple and easy to implement, which greatly reduces the production cost.

[0026] (3) The cobalt-doped composition of the present invention has the advantages of high efficiency, good stability, wide pH range of operation and no influence from environmental matrix (such as chloride ions, nitrates, carbonates and humic substances) in the process of degrading pollutants, and has broad application prospects in the treatment of organic pollutants. Attached Figure Description

[0027] Figure 1 The image shows the X-ray diffraction pattern of the cobalt-doped biomass prepared in Example 1.

[0028] Figure 2 This is a scanning electron microscope image of the cobalt-doped biomass prepared in Example 1;

[0029] Figure 3 The image shows the degradation effect of cobalt-doped biomass and peracetic acid in Example 1 on ciprofloxacin.

[0030] Figure 4 The graph shows the effect of the amount of cobalt-doped biomass on the degradation efficiency of ciprofloxacin in Example 2.

[0031] Figure 5 The graph shows the effect of the amount of peracetic acid on the degradation efficiency of ciprofloxacin in Example 4.

[0032] Figure 6 This is a graph showing the effect of pH on the degradation efficiency of ciprofloxacin in Example 5;

[0033] Figure 7 The graph shows the effect of chloride ion concentration on the degradation efficiency of ciprofloxacin in Example 6.

[0034] Figure 8 The graph shows the effect of nitrate concentration on the degradation efficiency of ciprofloxacin in Example 7.

[0035] Figure 9 This is a graph showing the effect of carbonate concentration on the degradation efficiency of ciprofloxacin in Example 8;

[0036] Figure 10 Image of the effect of humic acid concentration on the degradation efficiency of ciprofloxacin in Example 9. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments to illustrate its outstanding features. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] Example 1

[0039] This embodiment of a method for treating organic pollution with a cobalt-doped composition includes the following steps:

[0040] (1) Preparation of cobalt-doped biomass formulations

[0041] Step 1: Weigh 4g of oyster shell powder and 2g of potassium hydroxide (analytical grade), place the two solids in the same mortar and grind them to mix them thoroughly, then transfer the ground mixture to a ceramic crucible.

[0042] Step 2: Place the ceramic crucible containing the mixed solids into a tube furnace. Before calcination, purge with nitrogen (flow rate 0.4 L / min) for half an hour to remove air from the quartz tube. Then set the temperature program as follows: start heating from room temperature at a rate of 5 °C / min, hold at 200 °C for 30 min, then increase the temperature at a rate of 5 °C / min to the calcination temperature (calcination temperature set to 500 °C) and hold for 4 h. After calcination, allow to anneal and cool naturally.

[0043] Step 3: The solid obtained in Step 2 is centrifuged and washed multiple times with deionized water and ethanol. After washing, it is dried in an oven or freeze dryer at a temperature of 75°C. The freeze drying conditions are set to a pressure of 1 mbar and a freezing temperature of -40°C to obtain a solid powder.

[0044] Step 4: Weigh 2g of the solid powder obtained in Step 3, 0.75g of potassium chloride, 0.425g of lithium chloride, and 0.12g of cobalt chloride. Place the solids in the same mortar and grind them to mix them thoroughly. Transfer the ground mixture to a ceramic crucible.

[0045] Step 5: Place the ceramic crucible containing the mixed solid from Step 4 into a tube furnace. Before calcination, purge with nitrogen (flow rate 0.4 L / min) for half an hour to remove air from the quartz tube. Then set the temperature program as follows: start heating from room temperature at a rate of 5 °C / min, hold at 200 °C for 30 min, then increase the temperature at a rate of 5 °C / min to the calcination temperature (calcination temperature set to 500 °C) and hold for 4 h. After calcination, allow to anneal and cool naturally.

[0046] Step Six: The solid obtained in Step Five is washed multiple times by centrifugation with deionized water and ethanol. After washing, it is dried using an oven or freeze dryer at 75°C. The freeze-drying conditions are set to a pressure of 1 mbar and a freezing temperature of -40°C to obtain cobalt-doped biomass. The X-ray diffraction pattern of the cobalt-doped biomass prepared in this embodiment is shown below. Figure 1 As shown, the scanning electron microscope image of the cobalt-doped biomass is as follows: Figure 2 As shown.

[0047] (2) Preparation of peracetic acid preparations

[0048] Equal volumes of 9 mol / L hydrogen peroxide solution, 6 mol / L acetic acid, and 1.5 mol / L sulfuric acid were mixed, with the molar ratio of hydrogen peroxide, acetic acid, and sulfuric acid being 3:2:0.5. The mixture was then stirred thoroughly for at least 24 hours to obtain a peracetic acid preparation.

[0049] (3) Treatment of organic pollutants

[0050] Step 1: Add the composition containing cobalt-doped biomass preparation and peracetic acid preparation to wastewater containing organic pollutants to obtain a mixed solution, wherein the concentration of cobalt-doped biomass preparation is 0.5 g / L, the concentration of peracetic acid preparation is 2 mM, the concentration of pollutant ciprofloxacin is 6.6 mg / L, and the pH of the system is maintained at 7 using 20 mM phosphate buffer.

[0051] Step 2: Stir the mixture solution from Step 1 for 2-10 minutes at a stirring speed of 100-120 r / min. The reaction shall be carried out at room temperature and atmospheric pressure.

[0052] Step 3: Perform solid-liquid separation on the mixture solution after the reaction in Step 2 to recover the solid.

[0053] This embodiment utilizes cobalt-doped Co(II) on the surface of biomass, which can rapidly transfer electrons to activate peracetic acid, generating highly oxidizing peroxyacyl radicals, thereby achieving the purpose of rapidly degrading the target pollutant. The effect of degrading ciprofloxacin is as follows: Figure 3 As shown.

[0054] This embodiment is based on cobalt-supported biomass to activate peracetic acid to generate peroxyacyl radicals. It can react rapidly at room temperature and pressure, consumes little energy, is simple to operate, and has extremely high degradation efficiency for pollutants, reaching up to 90%.

[0055] Example 2

[0056] The basic content of this embodiment is the same as that of Embodiment 1, except that the amount of cobalt-doped biomass agent is different in the organic pollutant treatment steps. This embodiment examines the treatment effect of cobalt-doped biomass agent at concentrations of 0.1 g / L, 0.2 g / L, 0.4 g / L, and 0.5 g / L on a pretreated pollutant solution containing ciprofloxacin (initial concentration of 6.6 mg / L).

[0057] like Figure 4 As shown, the treatment effect of cobalt-doped biomass formulation is best when the amount is 0.5 g / L. This is because high doses of cobalt-doped biomass can rapidly activate peracetic acid to generate a large number of free radicals, thereby accelerating the degradation of pollutants.

[0058] Example 3

[0059] The basic content of this embodiment is the same as that of Embodiment 1, except that the amount of peracetic acid preparation is different in the treatment steps of organic pollutants. This embodiment examines the treatment effect of peracetic acid at amounts of 0.2 mM, 0.5 mM, 1.0 mM, and 2.0 mM on a pretreated pollutant solution of ciprofloxacin (initial concentration of 6.6 mg / L).

[0060] like Figure 5 As shown, the treatment effect of peracetic acid at a concentration of 2 mM is optimal for ciprofloxacin because high doses of peracetic acid generate a large number of free radicals, which rapidly degrade ciprofloxacin.

[0061] Example 4

[0062] The basic content of this embodiment is the same as that of Embodiment 1, except that the pH of the mixed solution in the organic pollutant treatment step is 3, 5, 7, 9 and 11 respectively.

[0063] like Figure 6 As shown, within a pH range of 3-11, cobalt-doped biomass can efficiently activate peracetic acid to rapidly degrade ciprofloxacin, demonstrating the wide pH applicability of this composition.

[0064] Example 5

[0065] The basic content of this embodiment is the same as that of embodiment 1, except that in the treatment step of organic pollutants, chloride ions with a concentration of 17.5-177.5 mg / L are added to the wastewater (the source of chloride ions is the addition of sodium chloride of the corresponding concentration).

[0066] like Figure 7 As shown, within the chloride ion concentration range of 17.5-177.5 mg / L, the cobalt-doped compositions all exhibited highly efficient degradation of ciprofloxacin. Chloride ions did not affect the degradation of ciprofloxacin by the compositions, indicating that even in the presence of a large amount of chloride ions in the environment, cobalt-doped biomass can still activate peracetic acid to efficiently remove ciprofloxacin.

[0067] Example 6

[0068] The basic content of this embodiment is the same as that of Embodiment 1, except that in the treatment step of organic pollutants, nitrate with a concentration of 31-310 mg / L is added to the wastewater (the source of nitrate ions is the addition of sodium nitrate of the corresponding concentration).

[0069] like Figure 8 As shown, the cobalt-doped compositions exhibited highly efficient degradation of ciprofloxacin in the nitrate concentration range of 31-310 mg / L. Nitrate did not affect the degradation of ciprofloxacin by the compositions, indicating that even in the presence of large amounts of nitrate in the environment, cobalt-doped biomass can still activate peracetic acid to efficiently remove ciprofloxacin.

[0070] Example 7

[0071] The basic content of this embodiment is the same as that of embodiment 1, except that: in the treatment step of organic pollutants, carbonate with a concentration of 30.5-305.0 mg / L is added to the wastewater (the carbonate is obtained by adding sodium carbonate of the corresponding concentration).

[0072] like Figure 9 As shown, within the carbonate concentration range of 30.5-305.0 mg / L, the cobalt-doped compositions exhibited highly efficient degradation of ciprofloxacin. Carbonate did not affect the degradation of ciprofloxacin by the compositions, indicating that even in the presence of large amounts of carbonate in the environment, cobalt-doped biomass can still activate peracetic acid to efficiently remove ciprofloxacin.

[0073] Example 8

[0074] The basic content of this embodiment is the same as that of embodiment 1, except that in the treatment step of organic pollutants, organic carbon with a concentration of 10-50 mg / L is added to the wastewater (the source of organic carbon is the addition of humic acid at the corresponding concentration).

[0075] like Figure 10 As shown, the cobalt-doped compositions exhibited highly efficient degradation of ciprofloxacin at organic carbon concentrations of 10-50 mg / L. Organic carbon did not affect the degradation of ciprofloxacin by the compositions, indicating that even in the presence of large amounts of organic carbon in the environment, cobalt-doped biomass can still activate peracetic acid to efficiently remove ciprofloxacin.

[0076] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the data used is only one embodiment of the present invention. The actual combination of data is not limited to this. Therefore, if those skilled in the art are inspired by this description and, without departing from the spirit of the present invention, devise similar embodiments and examples of the technical solution without creative design, all such embodiments and examples should fall within the protection scope of the present invention.

Claims

1. A cobalt-doped composition, characterized in that: The invention comprises a cobalt-doped biomass preparation and a peracetic acid preparation. The cobalt-doped biomass preparation is shellfish shell biomass with cobalt doped on its surface. The effective components of the peracetic acid preparation are peracetic acid and hydrogen peroxide. The cobalt-doped biomass preparation is prepared via a high-temperature molten salt method. The specific process involves mixing shellfish shell powder with an alkali metal hydroxide, grinding, and then subjecting it to a first high-temperature treatment. After treatment, the mixture is cooled, washed, and dried to obtain a solid powder. The solid powder is then mixed with potassium chloride, lithium chloride, and cobalt chloride, ground, and subjected to a second high-temperature treatment. After treatment, the mixture is cooled, washed, and dried to obtain the cobalt-doped biomass preparation. The mass ratio of the shellfish shell powder to the alkali metal hydroxide is 2:

1. The shellfish shell is oyster shell, and the alkali metal hydroxide is potassium hydroxide.

2. The cobalt-doped composition of claim 1, wherein: The molar ratio between the cobalt-doped biomass preparation and the peracetic acid preparation is 0.25-0.5; or, the peracetic acid preparation is a peracetic acid solution containing hydrogen peroxide, peracetic acid and sulfuric acid in a molar ratio of 3:2:0.

5.

3. The cobalt-doped composition of claim 1, wherein: The material ratio of the solid powder obtained after the first high-temperature treatment to potassium chloride, lithium chloride, and cobalt chloride was set as follows: under the condition of 2 g of solid powder, the amounts of potassium chloride, lithium chloride, and cobalt chloride were 10 mM, 10 mM, and x mM, respectively, where x = 0.5, 1, 2, or 4.

4. The cobalt-doped composition of claim 1, wherein: The specific processes for the first and second high-temperature treatments are as follows: starting from room temperature, the temperature is increased at a rate of 5℃ / min, and after reaching 200℃, it is held for 30 min. Then, the temperature is increased at a rate of 5℃ / min to 500℃ and held for 4 h. After calcination, the temperature is naturally annealed and cooled. Alternatively, the drying is either oven drying or freeze drying, wherein the oven drying temperature is 75℃, and the freeze drying conditions are a pressure of 1 mbar and a temperature of -40℃.

5. A cobalt-doped composition according to any one of claims 1 to 4, wherein: The first and second high-temperature treatments are carried out in a nitrogen atmosphere or under air-isolated conditions.

6. Use of a cobalt-doped composition for the degradation of organic pollutants, characterized in that: The method includes adding the cobalt-doped composition according to any one of claims 1-4 to wastewater containing organic pollutants to obtain a mixed solution, mixing and reacting for 2-10 min, and then separating and recovering the mixed solution after the reaction, wherein the organic pollutant is ciprofloxacin.

7. Use according to claim 6, characterized in that: The concentration of the cobalt-doped biomass preparation in the mixture solution is 0.1-0.5 g / L, and the concentration of the peracetic acid preparation is 0.2-2.0 mM.

8. Use according to claim 6, characterized in that: The wastewater also contains chloride ion concentrations of 17.5-177.5 mg / L, nitrate concentrations of 31-310 mg / L, carbonate concentrations of 30.5-305.0 mg / L, or organic carbon concentrations of 10-50 mg / L. Alternatively, the pH of the reaction system can be 3-11.

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