CN114314799A

CN114314799A - Improved Fenton system and method for treating organic pollutants by utilizing same

Info

Publication number: CN114314799A
Application number: CN202111672059.1A
Authority: CN
Inventors: 陈飞; 侯坤杰; 杨麒
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2022-04-12

Abstract

The invention discloses an improved Fenton system and a method for treating organic pollutants by using the same; an improved Fenton system is characterized in that the system adopts trivalent ferric salt to activate H₂O₂And at the same time adding co-activator Na into the system₂S to promote the circulation of ferric and ferrous salts and finally promote H₂O₂Activated to generate active oxygen substances, so that the degradation efficiency of organic pollutants is improved; the invention uses Fe³⁺Substituted for Fe²⁺By addition of Fe to³⁺And H₂O₂Adding S to the system^2‑Successfully overcomes the original defects of the traditional Fenton system, has the characteristics of economy, energy conservation and environmental protection, and can effectively promote Fe in the Fenton system³⁺With Fe²⁺The method has the characteristics of high organic pollutant removal efficiency, wide applicable pH range and the like, generates no toxic by-products, is suitable for the treatment of phenolic substances, salt-containing wastewater and the like, and can be widely applied to the fields of environmental protection, chemical engineering, textile and the like.

Description

Improved Fenton system and method for treating organic pollutants by utilizing same

Technical Field

The invention relates to the technical field of organic pollutant treatment, in particular to an improved Fenton system and a method for treating organic pollutants by using the same.

Background

The fenton system has been widely used in the treatment of industrial wastewater that is difficult to be biodegraded, and is often used in the pretreatment of domestic sewage. The traditional fenton system is composed of hydrogen peroxide and ferrous salts. Wherein Fe²⁺Can provide an electron to H₂O₂Then, H₂O₂Followed by dissociation to form hydroxyl (OH)^-) And a hydroxyl radical (. OH) (formula 1). Wherein, OH has strong oxidizability and can oxidize and degrade most organic pollutants. However, due to the conventional Fenton system (H)₂O₂/Fe²⁺) In, Fe²⁺Supply electrons to H₂O₂Then oxidized to Fe³⁺And is of Fe³⁺In the conventional Fenton system (H)₂O₂/Fe²⁺) In the middle to Fe²⁺Has very low efficiency (formula 2-3), which results in that the traditional Fenton system needs to increase H to achieve better pollutant removal effect₂O₂And Fe²⁺The amount of (A) to (B). In addition, due to Fe²⁺Salts are easily oxidized, their chemical instability leads to additional storage costs, and Fe³⁺/Fe²⁺Fe caused by too slow cycling²⁺/H₂O₂Limited degradation of contaminants in the system, etc. Therefore, how to accelerate Fe²⁺In the activation of H₂O₂The iron-based material activation H is formed by cyclic regeneration in the process₂O₂A research hotspot of the system. For example, researchers have been working with Fe²⁺/H₂O₂The conventional reducing agent hydroxylamine hydrochloride is introduced into the system, and the discovery shows that a proper amount of hydroxylamine hydrochloride can accelerate Fe under the condition of not influencing the degradation of pollutants by free radicals²⁺/Fe³⁺Thereby greatly promoting Fe²⁺Activation of H₂O₂The reaction of generating free radicals further improves the degradation rate of benzoic acid. Other investigators have found that certain reducing organic compounds such as gallic acid (galloc acid), gallocatechin gallate (epigallocatechin-3-gallate), hydroquinone (hydroquinone), and benzoquinone (benzoquinone)quinone) and the like can also promote Fe²⁺/Fe³⁺Thereby accelerating Fe²⁺/H₂O₂Or Fe³⁺/H₂O₂In the system H₂O₂The efficiency of generating free radicals is activated, and the removal rate of organic pollutants is finally improved. In addition, researchers have used an electrochemical device-assisted method to directly utilize electrodes to supply Fe in an electrolyte³⁺Supply electrons to reduce them to Fe²⁺Thereby obviously quickening Fe²⁺/Fe³⁺Greatly enhances H₂O₂The efficiency of activating and degrading organic pollutants. However, although the above method can be effective in increasing Fe to some extent²⁺/H₂O₂The efficiency of the system in removing pollutants, however, some problems of the methods are not negligible at present. For example, hydroxylamine is chemically unstable and a toxic substance, and thus it is exposed to high storage and use costs and risks of secondary pollution in practical applications. And the extra addition of organic matters into the system can increase the Total Organic Carbon (TOC) content in the system, thereby causing troubles to subsequent treatment and even forming secondary organic pollution. Although the electrochemical-assisted method avoids the above disadvantages, it requires relatively high operation costs due to the need for equipment construction before operation and power consumption during operation, thereby limiting its application range.

Disclosure of Invention

The present invention is directed to an improved Fenton system and a method for treating organic pollutants using the same.

In order to achieve the purpose, the invention adopts the following technical scheme:

an improved Fenton system is characterized in that the system adopts trivalent ferric salt to activate H₂O₂And at the same time adding co-activator Na into the system₂S, ultimately promoting H₂O₂Activated to generate active oxygen substances, thereby improving the degradation efficiency of organic pollutants.

The invention uses Fe³⁺Substituted for Fe²⁺By addition of Fe to³⁺And H₂O₂Adding S to the system^2-Successfully overcomes the original Fenton Fe²⁺And H₂O₂The defects of the system are as follows: for example due to Fe²⁺Additional storage costs due to instability, and due to Fe³⁺To Fe²⁺Fe caused by too slow cycling²⁺/H₂O₂The degradation of pollutants in the system is limited, and the like, so that the invention greatly accelerates the Fe³⁺To Fe²⁺Is circulated, H is increased₂O₂The activation efficiency of (a) and the removal efficiency of organic contaminants.

The invention provides a stable H₂O₂Activator Fe of (2)³⁺In addition to the salt, promoting Fe is proposed³⁺And H₂O₂Fe in the system³⁺To Fe²⁺A method of accelerating cycling, comprising: to Fe³⁺/H₂O₂Adding Fe into the system³⁺Salt co-activator Na₂S, thereby greatly accelerating Fe²⁺/Fe³⁺Circulation of (2), H₂O₂And the efficiency of removal of the target contaminant.

The second technical scheme of the invention is a method for treating organic pollutants by utilizing an improved Fenton system, which is characterized by comprising the following steps:

step one, configuring H₂O₂The activator comprises a mother liquor of an aqueous solution of a ferric salt and Na₂An aqueous mother liquor of S;

step two, configuration H₂O₂As an oxidizing agent;

step three, mixing H₂O₂And aqueous mother liquor of ferric salt and Na₂And adding the aqueous solution mother liquor of the S into the organic pollutants to degrade the organic pollutants.

According to the preferable scheme of the method for treating the organic pollutants by using the improved Fenton system, the adding amount of the ferric iron salt in the third step is 0.018-0.107 mmol/L.

The method for treating organic pollutants by utilizing the improved Fenton system has the advantages ofThe Na is selected from the third step₂The addition amount of S is 0.02-0.1 mmol/L.

According to a preferred embodiment of the method for treating organic pollutants by using the modified Fenton system, H is adopted in the third step₂O₂The amount of the additive is 0.25 to 2.0 mmol/L.

According to a preferred embodiment of the method for treating organic pollutants by using the modified Fenton system, the ferric salt is Fe (NO)₃)₃Or Fe₂(SO₄)₃。

According to a preferred embodiment of the method for treating organic pollutants by using the modified fenton system, the organic pollutants comprise phenolic substances.

Compared with the traditional Fenton system, the invention has the following differences:

the reaction formula of the traditional Fenton system is as follows:

H₂O₂+Fe²⁺→Fe³⁺+OH^-+·OH k＝40-80L mol^-1s^-1 (1)

H₂O₂+Fe³⁺→Fe²⁺+H⁺+·O₂H k＝9.1×10^-7Lmol^-1s^-1 (2)

Fe³⁺+·O₂H→Fe²⁺+H⁺+O₂ k＝0.33-2.1×10⁶L mol^-1s^-1 (3)

the reaction formula of the improved Fenton system is as follows:

Fe³⁺+S^2-→Fe²⁺+S⁰ (4)

H₂O₂+Fe²⁺→Fe³⁺+OH^-+·OH k＝40-80L mol^-1s^-1 (8)

the improved Fenton system and the method for treating organic pollutants by using the same have the beneficial effects that: in the present invention, Fe is used³⁺Substituted for Fe²⁺And by addition of Fe to³⁺/H₂O₂Adding S to the system^2-Successfully overcomes the defects of the traditional Fenton system, has the characteristics of economy, energy conservation and environmental protection, and can effectively promote Fe in the Fenton system³⁺To Fe²⁺The method has the characteristics of high organic pollutant removal efficiency, wide applicable pH range and the like, generates no toxic by-products, is suitable for the treatment of phenolic substances, salt-containing wastewater and the like, and can be widely applied to the fields of environmental protection, chemical engineering, textile and the like.

Drawings

FIG. 1 shows Fe constructed according to the present invention³⁺/S²-/H₂O₂Improved Fenton system compared with traditional Fenton system and H without adding co-activator sodium sulfide₂O₂/Fe³⁺The advantages of the system of (1) are compared.

FIG. 2 shows Fe constructed according to the present invention³⁺/S^2-/H₂O₂The improved Fenton system is a graph of the degradation efficiency of target pollutants under different pH conditions.

FIG. 3 shows Fe constructed according to the present invention³⁺/S^2-/H₂O₂The improved Fenton system is used for degrading target pollutants under anaerobic and aerobic conditions.

FIG. 4 shows Fe constructed according to the present invention³⁺/S^2-/H₂O₂Improved Fenton systems in different Cl^-Graph of the efficiency of degradation of target contaminants under concentration conditions.

Detailed Description

An improved Fenton system which uses a ferric salt to activate H₂O₂And at the same time adding co-activator Na into the system₂S to promote the circulation of the ferric iron salt to the ferrous iron salt and finally promote H₂O₂Activated to generate active oxygen speciesAnd the degradation efficiency of organic pollutants is improved.

A method for treating organic pollutants using a modified fenton system, the method comprising the steps of:

step two, configuration H₂O₂As an oxidizing agent;

In a specific embodiment, the dosage of the ferric iron salt in the third step is 0.018 to 0.107mmol/L, and preferably 0.071 mmol/L.

Na mentioned in step three₂The addition amount of S is 0.02-0.1 mmol/L, preferably 0.02 mmol/L.

Step three, the above H₂O₂The amount of the compound is 0.25 to 2.0mmol/L, preferably 0.05 mmol/L.

The ferric salt is Fe (NO)₃)₃Or Fe₂(SO₄)₃。

The organic pollutants comprise phenolic substances and salt-containing wastewater (Cl)^-) And the like.

Example 1: preparation of activators, co-activators and oxidizer mother liquors

1.925g of Na are weighed by an electronic balance₂S·9H₂O, then adding it to a clean 250mL jar with a lid, adding 200mL deionized water, tightening the lid, sonicating or shaking Na₂S·9H₂O is completely dissolved to obtain 200mL of 4mmol/L Na₂And (5) mother liquor S.

1.154g of Fe (NO) was weighed using an electronic balance₃)₃·9H₂O, then added to a clean 250mL jar with a lid, 200mL deionized water was added, the lid was tightened, and Fe (NO) was sonicated or shaken₃)₃·9H₂O is completely dissolved to obtain 200mL of 14.2mmol/L Fe (NO)₃)₃And (4) mother liquor.

Draw 2mL of H with pipette₂O₂Adding the stock solution into a clean 250mL wide-mouth bottle with a cover, adding 200mL deionized water, screwing the bottle cover, shaking or stirring to completely dissolve the stock solution to obtain 200mL of 100mmol/L H₂O₂And (4) mother liquor.

Example 2: constructed Fe³⁺/S^2-/H₂O₂Application and advantages of improved Fenton system in removal of bisphenol A in water

First, 200mL of a 20mg/L BPA solution was prepared in a 300mL clean beaker and the pH was adjusted to around 5.6 using sulfuric acid or sodium hydroxide. 1mL of Fe (NO) prepared in example 1 was added thereto, respectively₃)₃Mother liquor and 0.5mL of H₂O₂Mother liquor, finally 1mL of Na is added₂And (S) carrying out mixing reaction on the S mother liquor by using a magnetic stirrer at the room temperature, sampling at the time points of 2 min, 5min, 10 min, 15min and 30min at the rotation speed of about 200rpm, and measuring the concentration of BPA (bisphenol A) in each reaction node by using high performance liquid chromatography.

As a result, as shown in FIG. 1, it was found that Fe constructed in the present invention³⁺/S^2-/H₂O₂The degradation rate of BPA in the improved Fenton system within 30min is close to 100 percent, and the performance is obviously better than that of the BPA without adding the co-activator S^2-H of (A) to (B)₂O₂/Fe³⁺System and conventional Fenton system (H)₂O₂/Fe²⁺)。

Example 3: constructed Fe³⁺/S^2-/H₂O₂Application of improved Fenton system in removal of bisphenol A in water under different initial pH conditions

First, 3 sets of 200mL BPA solutions with a concentration of 20mg/L were placed in a 300mL clean beaker and the pH was adjusted to approximately 3.2, 5.6, and 8.65 using sulfuric acid or sodium hydroxide, respectively. 1mL of Fe (NO) prepared in example 1 was added thereto, respectively₃)₃Mother liquor and 0.5mL of H₂O₂Mother liquor, finally 1mL of Na is added₂And (S) carrying out mixing reaction on the S mother liquor by using a magnetic stirrer at the room temperature, sampling at the time points of 2 min, 5min, 10 min, 15min and 30min at the rotation speed of about 200rpm, and measuring the concentration of BPA (bisphenol A) in each reaction node by using high performance liquid chromatography.

As a result, as shown in FIG. 2, it was found that Fe was constructed in the present invention³⁺/S^2-/H₂O₂In the modified fenton system, the rate of BPA reduction within 15min was close to 100% when the initial pH was 3.2. Under the condition that the pH value is 5.6, the degradation rate of BPA within 30min is close to 100%, more importantly, when the initial pH value is 8.65, the degradation rate of BPA is only slightly inhibited, and the degradation rate of BPA within 30min is still as high as 90%, which further indicates that compared with the narrower pH application range (pH value is 3-5) of the traditional Fenton system, the Fe constructed by the invention is suitable for the application range of Fe constructed by the invention³⁺/S^2-/H₂O₂The improved Fenton system has wide pH application range and good pollutant removal effect.

Example 4: constructed Fe³⁺/S^2-/H₂O₂Application of improved Fenton system in removing bisphenol A in water under anaerobic condition

First, 200mL of BPA solution with a concentration of 20mg/L is placed in a 300mL clean beaker, the pH is adjusted to about 5.6 by using sulfuric acid or sodium hydroxide, and N is continuously introduced into the beaker₂At least 60min to discharge dissolved oxygen contained in the solution. 1mL of Fe (NO) prepared in example 1 was added thereto, respectively₃)₃Mother liquor and 0.5mL of H₂O₂Mother liquor, finally 1mL of Na is added₂S mother liquor, introducing N at room temperature₂The mixture was subjected to a mixing reaction with a magnetic stirrer at a rotation speed of about 200rpm, and samples were taken at time points of 2, 5, 10, 15 and 30min, and the concentration of BPA at each reaction node was measured by high performance liquid chromatography.

The results in FIG. 3 demonstrate that although anaerobic conditions may provide some inhibition to the system of the present invention, the inhibition is very small, and the degradation rate of bisphenol A in anaerobic conditions is 30mThe degradation rate in-in still reaches more than 90 percent, and shows that the Fe constructed by the invention³⁺/S^2-/H₂O₂The improved Fenton system can achieve a good effect of removing pollutants in a common aerobic environment, can also effectively degrade the pollutants under an anaerobic condition, and further widens the application scene of the invention.

Example 5: fe built up in the presence of chloride ions³⁺/S^2-/H₂O₂Application of improved Fenton system in removal of bisphenol A in water

Firstly, 4 groups of 200mL BPA solution with the concentration of 20mg/L are prepared in a 300mL clean beaker, the pH value is adjusted to be about 5.6 by utilizing sulfuric acid or sodium hydroxide, NaCl is respectively added into the beaker to ensure that Cl is contained in the solution^-Are 0, 0.1, 0.5 and 1.0mmol/L, respectively. Thereafter, 1mL of Fe (NO) prepared in example 1 was added thereto, respectively₃)₃Mother liquor and 0.5mL of H₂O₂Mother liquor, finally 1mL of Na is added₂And (S) carrying out mixing reaction on the S mother liquor by using a magnetic stirrer at the room temperature, sampling at the time points of 2 min, 5min, 10 min, 15min and 30min at the rotation speed of about 200rpm, and measuring the concentration of BPA (bisphenol A) in each reaction node by using high performance liquid chromatography.

The results in FIG. 4 show that 0.1-1.0mmol/L Cl^-Not only Fe not constructed for the present invention³⁺/S^2-/H₂O₂The improved Fenton system inhibits the removal of BPA and plays a role in promoting the removal of BPA, which shows that the Fe constructed by the invention³⁺/S^2-/H₂O₂The modified Fenton system has strong resistance to the interference of chloride ions which are common in the environment.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. Improvement of a kind ofThe Fenton system is characterized in that the system adopts trivalent ferric salt to activate H₂O₂And at the same time adding co-activator Na into the system₂S to promote the circulation of ferric and ferrous salts and finally promote H₂O₂Activated to generate active oxygen substances, thereby improving the degradation efficiency of organic pollutants.

2. A method for treating organic pollutants by using an improved Fenton system is characterized by comprising the following steps:

step two, configuration H₂O₂As an oxidizing agent;

3. The method for treating organic pollutants by using the improved Fenton system according to claim 2, wherein the dosage of the ferric iron salt in the third step is 0.018-0.107 mmol/L.

4. The method of claim 2, wherein Na is added in step three₂The addition amount of S is 0.02-0.1 mmol/L.

5. The method of claim 2, wherein H is the same as H in step III₂O₂The amount of the additive is 0.25 to 2.0 mmol/L.

6. The method for treating organic pollutants with the modified Fenton's system in accordance with claim 2, wherein said ferric salt is Fe (NO)₃)₃Or Fe₂(SO₄)₃。

7. A method for treating organic pollutants using a modified Fenton's system in accordance with claim 2, wherein said organic pollutants comprise phenolic substances.