Method for treating organic wastewater by iron-based composite material activated molecular oxygen

Abstract

This invention provides a method for treating organic wastewater by activating molecular oxygen with an iron-based composite material, belonging to the field of wastewater treatment technology. The invention involves ball milling red phosphorus, iron salts, and activated carbon under an inert gas atmosphere to obtain an iron-based composite material. This iron-based composite material, in an air or oxygen atmosphere within an organic wastewater system, generates H2O2 in situ through the activation of molecular oxygen, which then reacts with the generated Fe... 2+ The Fenton reaction is formed, which degrades organic pollutants in water. The iron-based composite material obtained by this invention can simultaneously degrade antibiotics, dyes, and phenolic wastes in organic wastewater, with excellent degradation efficiency for all of them.

Description

Technical Field

[0001] This invention relates to the field of water pollution treatment technology, and in particular to a method for treating organic wastewater by activating molecular oxygen with iron-based composite materials. Background Technology

[0002] With the rapid development of modern industrialization and economic globalization, large amounts of industrial wastewater are becoming a serious global environmental problem. Under natural conditions, industrial wastewater is usually highly toxic and chemically stable, thus causing great harm to the ecological environment.

[0003] Currently, the main treatment methods for organic industrial wastewater are advanced oxidation processes, including the Fenton process, persulfate activation, and photocatalysis. However, the Fenton process requires the addition of expensive and chemically unstable H₂O₂. While the persulfate activation process uses relatively stable persulfate or persulfate, the final byproduct is sulfate, introducing new instability into the water body and posing new safety risks for future water treatment. Photocatalysis utilizes sunlight to excite semiconductors to generate free radicals; however, the preparation of high-efficiency semiconductor materials, the utilization rate of sunlight (affected by weather), and practical application remain significant challenges.

[0004] Molecular oxygen activation technology uses a catalyst to directly reduce oxygen in the air into superoxide anions (O2). ·- O2 ·- The pollutants are further reduced to H₂O₂, which is then decomposed to produce ·OH. This process requires no light or electricity, is unaffected by weather, and does not require additional oxidants (hydrogen peroxide and persulfate). Existing molecular oxygen activation materials, such as Fe / FeS composite catalysts and polythiophene / zero-valent iron composites, require the addition of additional chelating agents or reducing agents. This not only increases the reagent cost of molecular oxygen activation technology but also reduces the degradation rate of the target pollutants and causes secondary pollution.

[0005] Therefore, how to obtain an iron-based composite material with readily available raw materials, high degradation rate, and no pollution for molecular oxygen activation treatment of organic wastewater is a technical problem that needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a method for treating organic wastewater by activating molecular oxygen with iron-based composite materials, in order to solve the above-mentioned technical problems.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for treating organic wastewater by activating molecular oxygen with an iron-based composite material. The method involves adding an iron-based composite material as a catalyst to the organic wastewater and reacting it in an atmosphere of air or oxygen. H₂O₂ is generated in situ by activating molecular oxygen, which then reacts with the generated Fe. 2+ The Fenton reaction is formed, which degrades organic pollutants in water;

[0009] The preparation method of the iron-based composite material includes the following steps:

[0010] Red phosphorus, iron salts, and activated carbon were ball-milled under an inert gas atmosphere to obtain an iron-based composite material, wherein the activated carbon was subjected to acid leaching treatment.

[0011] Furthermore, the mass ratio of red phosphorus, iron salt and activated carbon is 0.1-0.5:1:1-10.

[0012] Furthermore, the iron salt comprises one or more of ferric sulfate, ferric chloride, and ferric nitrate.

[0013] Furthermore, the ball milling process is carried out at a rotation speed of 600–1000 rpm and for a duration of 50–100 min.

[0014] Furthermore, the acid leaching treatment includes: impregnating the activated carbon with dilute acid, washing the impregnated activated carbon until the pH is 5-7, and then drying it.

[0015] Furthermore, the volume concentration of the dilute acid is 20-40%.

[0016] Furthermore, the concentration of the iron-based composite material in the organic wastewater is 1–20 g / L.

[0017] Furthermore, the reaction temperature is 20–40°C.

[0018] Furthermore, the initial pH of the organic wastewater is 3 to 10.

[0019] The beneficial effects of this invention are:

[0020] In this invention, the activated carbon undergoes acid leaching, retaining a certain degree of acidity without releasing it into the aqueous solution, thus providing a locally acidic environment for the subsequent activation of molecular oxygen. During high-speed ball milling, the iron salts form numerous irregular surfaces, exposing iron active sites and providing reaction sites for the subsequent Fenton reaction. Red phosphorus, possessing reducing capabilities, is incorporated into the composite material and, under high-speed ball milling, tightly binds with the activated carbon and iron salts, enabling the activation of molecular oxygen to generate O2. ·- O2 ·- It is further reduced to new H2O2, and can also continuously reduce Fe. 2+Under the influence of red phosphorus, the newly generated H2O2 reacts with the Fe reduced on the surface of the composite material. 2+ The Fenton reaction occurs, generating hydroxyl radicals to degrade organic pollutants in the water. Detailed Implementation

[0021] This invention provides a method for treating organic wastewater by activating molecular oxygen with an iron-based composite material. The method involves adding an iron-based composite material as a catalyst to the organic wastewater and reacting it in an atmosphere of air or oxygen. H₂O₂ is generated in situ by activating molecular oxygen, which then reacts with the generated Fe. 2+ The Fenton reaction is formed, which degrades organic pollutants in water;

[0022] The preparation method of the iron-based composite material includes the following steps:

[0023] Red phosphorus, iron salts, and activated carbon were ball-milled under an inert gas atmosphere to obtain an iron-based composite material, wherein the activated carbon was subjected to acid leaching treatment.

[0024] In this invention, the mass ratio of red phosphorus, iron salt and activated carbon is 0.1-0.5:1:1-10, preferably 0.2-0.4:1:2-8, and more preferably 0.3-0.4:1:4-6.

[0025] In this invention, the iron salt comprises one or more of ferric sulfate, ferric chloride and ferric nitrate, preferably ferric sulfate.

[0026] In this invention, the flow rate of air or oxygen introduced is 100-200 mL / min, preferably 150 mL / min; the introduction time is 1-3 h, preferably 2 h.

[0027] In this invention, the ball milling speed is 600-1000 rpm, preferably 700-900 rpm, and more preferably 800-850 rpm; the ball milling time is 50-100 min, preferably 60-90 min, and more preferably 70-80 min.

[0028] In this invention, the acid leaching treatment includes: impregnating activated carbon with dilute acid, washing the impregnated activated carbon until the pH is 5-7, preferably 6, and then drying it.

[0029] In this invention, the volume concentration of the dilute acid is 20-40%, preferably 25-35%, and more preferably 28-30%.

[0030] In this invention, the concentration of the iron-based composite material in organic wastewater is 1-20 g / L, preferably 2-18 g / L, and more preferably 5-15 g / L.

[0031] In this invention, the reaction temperature is 20–40°C, preferably 25–35°C, and more preferably 28–30°C.

[0032] In this invention, the initial pH of the organic wastewater is 3 to 10, preferably 7 to 10.

[0033] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0034] Example 1

[0035] Preparation of iron-based composite materials:

[0036] 0.4g of red phosphorus, 1g of ferric sulfate and 8g of activated carbon powder were placed in a ball mill under N2 protection and ball milled at 1000rpm for 60min to obtain the iron-based composite material.

[0037] Example 2

[0038] Preparation of iron-based composite materials:

[0039] 0.5g of red phosphorus, 1g of ferric chloride and 7.5g of activated carbon powder were placed in a ball mill under N2 protection and ball milled at 600 rpm for 100 min to obtain the iron-based composite material.

[0040] Example 3

[0041] Preparation of iron-based composite materials:

[0042] 0.1g of red phosphorus, 1g of ferric nitrate and 5.2g of activated carbon powder were placed in a ball mill under N2 protection and ball milled at 800 rpm for 80 min to obtain the iron-based composite material.

[0043] Example 4

[0044] Preparation of iron-based composite materials:

[0045] 0.3g of red phosphorus, 1g of ferric sulfate and 9g of activated carbon powder were placed in a ball mill under N2 protection and ball milled at 1000 rpm for 50 minutes to obtain the iron-based composite material.

[0046] Example 5

[0047] Preparation of iron-based composite materials:

[0048] 0.2g of red phosphorus, 1g of ferric chloride and 10g of activated carbon powder were placed in a ball mill under N2 protection and ball milled at 700rpm for 90min to obtain the iron-based composite material.

[0049] In Examples 1-5, the activated carbon was soaked in 35% dilute sulfuric acid for 20 minutes, then washed with deionized water to pH 6, and then naturally dried.

[0050] Application Example 1

[0051] (1) Prepare ibuprofen solutions with concentrations of 10ppm, 20ppm, 30ppm, 40ppm and 50ppm respectively;

[0052] (2) Take 60 mL of the ibuprofen solution from step (1) and put it into five 100 mL beakers respectively. Adjust the pH of the solution in the beakers to 6. Add the iron-based composite materials obtained in Examples 1 to 5 to the five beakers respectively, with an addition amount of 2 g / L. Stir the reaction by introducing oxygen at a rate of 100 mL / min. Take samples for testing at 30 min, 40 min and 60 min respectively. The test results are shown in Table 1 below:

[0053] Table 1. Ibuprofen degradation effect data

[0054]

[0055]

[0056] As can be seen from Table 1, the iron-based composite material obtained by the present invention can achieve a degradation rate of 96% for ibuprofen in wastewater within 60 minutes.

[0057] Application Example 2

[0058] Five 10 mL portions of Rhodamine B dye wastewater with a concentration of 2.4 mg / L were prepared, and the pH was adjusted to 3.5 with HCl or NaOH. The iron-based composite materials obtained in Examples 1-5 were added to the five portions of dye wastewater at a concentration of 1 g / L. Air was introduced at a rate of 150 mL / min for stirring and reaction. The degradation rate of Rhodamine B dye wastewater was measured after 100 min, as shown in Table 2 below.

[0059] Table 2 Degradation rate of Rhodamine B dye

[0060] Example 1 0.20 91.6 Example 2 0.18 95.5 Example 3 0.16 93.3 Example 4 0.10 95.8 Example 5 0.13 94.6

[0061] As shown in Table 2 above, the iron-based composite material can achieve a degradation rate of 95.8% for Rhodamine B dye within 100 minutes. It can degrade not only antibiotic-type organic pollutants but also organic dyes, thus improving the efficiency of organic wastewater treatment.

[0062] Application Example 3

[0063] 10 mL of 2,4-dichlorophenol wastewater with a concentration of 30.0 mg / L was prepared, and the pH was adjusted to 6.9 with HCl or NaOH. Oxygen was introduced at a flow rate of 100 mL / min. The iron-based composite materials obtained in Examples 1-5 were added to 5 portions of 2,4-dichlorophenol wastewater at a dosage of 1.2 g / L. After stirring and reacting for 100 min, the degradation rate of 2,4-dichlorophenol wastewater was measured, as shown in Table 3 below.

[0064] Table 32, Degradation rate of 4-dichlorophenol wastewater

[0065]

[0066]

[0067] As can be seen from Table 3 above, the degradation rate of 2,4-dichlorophenol by this iron-based composite material can reach 87.3% within 100 minutes, which can achieve the simultaneous degradation of a variety of organic wastes.

[0068] As can be seen from the above embodiments, the present invention provides a method for treating organic wastewater by activating molecular oxygen with an iron-based composite material. The present invention involves ball milling red phosphorus, iron salts, and activated carbon under an inert gas atmosphere to obtain an iron-based composite material. The obtained iron-based composite material, in an air or oxygen atmosphere within an organic wastewater system, generates H2O2 in situ through the activation of molecular oxygen, which then reacts with the generated Fe... 2+ The Fenton reaction is formed, which degrades organic pollutants in water. The iron-based composite material obtained by this invention can simultaneously degrade antibiotics, dyes, and phenolic wastes in organic wastewater, with excellent degradation efficiency for all of them.

[0069] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for treating organic wastewater with activated molecular oxygen using an iron-based composite material, characterized in that, In the organic wastewater, iron-based composite material is added as a catalyst, and the reaction is carried out under the atmosphere of air or oxygen, H2O2 is generated in situ by activating molecular oxygen, and Fe 2+ Fenton reaction is formed, and the organic pollutants in water are degraded; The preparation method of the iron-based composite material comprises the following steps: The red phosphorus, the iron salt and the activated carbon are subjected to ball milling treatment under inert gas to obtain the iron-based composite material, and the activated carbon is subjected to acid immersion treatment. The mass ratio of the red phosphorus, the iron salt and the activated carbon is 0.1-0.5:1:1-10. The rotating speed of the ball milling treatment is 600-1000 rpm, and the ball milling treatment time is 50-100 min.

2. The method of claim 1, wherein the iron-based composite material is activated by molecular oxygen to treat the organic wastewater. The iron salt comprises one or more of iron sulfate, iron chloride and iron nitrate.

3. The method of claim 1 or 2, wherein the iron-based composite material is activated by molecular oxygen to treat the organic wastewater. The acid immersion treatment comprises: infiltrating the activated carbon with dilute acid, cleaning the infiltrated activated carbon to a pH of 5-7, and drying.

4. The method of claim 3, wherein the iron-based composite material is activated by molecular oxygen to treat the organic wastewater. The volume concentration of the dilute acid is 20-40%.

5. The method of claim 1 or 4, wherein the iron-based composite material is activated by molecular oxygen to treat organic wastewater. The concentration of the iron-based composite material in the organic wastewater is 1-20 g / L.

6. The method of claim 5, wherein the iron-based composite material is activated by molecular oxygen to treat the organic wastewater. The reaction temperature is 20-40 DEG C.

7. The method of claim 1 or 6, wherein the iron-based composite material is activated by molecular oxygen to treat organic wastewater. The initial pH of the organic wastewater is 3-10.

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