CN110372048B

CN110372048B - Method for removing organic matters in water

Info

Publication number: CN110372048B
Application number: CN201910541979.6A
Authority: CN
Inventors: 宋伟; 王卓悦
Original assignee: Shenzhen Huichuangyuan Environmental Protection Technology Co ltd
Current assignee: Shenzhen Huichuangyuan Environmental Protection Technology Co ltd
Priority date: 2019-06-21
Filing date: 2019-06-21
Publication date: 2022-04-22
Anticipated expiration: 2039-06-21
Also published as: CN110372048A

Abstract

The invention discloses a method for removing organic matters in water, in particular to a method for degrading refractory organic pollutants by using iron ions to activate Dithionite (Dithionite), which comprises the following steps: selecting a water body containing refractory organic matters, adding dithionite and iron ions, adjusting the temperature and the pH value, and treating the refractory organic matters in the water body. The method can efficiently and conveniently treat the refractory organic matters in the organic wastewater, and has great application potential in the aspect of organic wastewater treatment.

Description

Method for removing organic matters in water

Technical Field

The invention belongs to the technical field of organic matter treatment, and particularly relates to a method for removing organic matters in water, in particular to a method for degrading refractory organic matters by activating Dithionite (Dithionite) with iron ions.

Background

The refractory organic matters are widely concerned because the structure is complex and stable and the conventional process is difficult to remove. At present, an effective treatment method for refractory organic matters is an advanced oxidation technology, and a series of highly-oxidative free radicals are generated in a system by means of activation, so that the refractory organic matters are effectively degraded. However, for organic matters which are difficult to degrade, such as halogenated organic matters, the advanced oxidation technology cannot effectively dehalogenate, so that the detoxification effect and complete degradation are difficult to achieve. Compared with the prior art, the high-grade reduction technology can effectively dehalogenate and reduce toxicity, and shows superiority.

Advanced reduction technology has attracted much attention and research in recent years, and corresponds to advanced oxidation technology, namely, a reducing agent is activated in a certain mode to generate a series of groups with high reduction activity, so that organic matters are degraded efficiently. The activation is to promote the breaking of some specific bonds in the reducing agent through energy intake or other substance addition, so as to generate reducing free radicals, so that the reducing agent can exert better reducing property. The advanced reduction technology is mainly used in the fields of organic halide dehalogenation, metal ion reduction, oxysalt reduction and the like, and is also applied to the remediation of flooded soil and iron-rich soil.

In the current research, the reducing agent includes sulfite, dithionite, ferrous iron, sulfide, etc., and the activating means mainly includes ultraviolet light, high-energy electron beam, microwave, etc. Selecting pollutants including chlorinated organic matters, atenolol and other refractory organic matters, perchlorate, nitrate and other inorganic matters. The reducing radical includes a hydrated electron (e)_aq-) having a standard redox potential of-2.9 eV; a hydrogen atom (H.) having a standard redox potential of-2.3 eV; sulfur dioxide free radical (SO)₂-) having a standard redox potential of-0.66 eV.

Dithionite is a strong reducing agent with an oxidation-reduction potential of-1.12 eV. The hydrosulfite solution is unstable and is easy to decompose. Sulfur dioxide and elemental sulfur are generated under acidic conditions, and sulfide and the like are generated under alkaline conditions. Under the irradiation of ultraviolet light, the S-S bond in the dithionite molecule is broken to generate two sulfur dioxide free radicals (SO)₂-), the specific reaction formula is shown as (formula 1-3):

S₂O₄ ^2-→2SO₂ ^.-(formula 1)

The dithionite is not researched in the field of advanced reduction, mainly comprises heavy metal reduction, oxysalt reduction and the like, and the degradation efficiency of organic pollutants is less researched. And the activation mode used by the sodium hydrosulfite advanced reduction technology is limited to ultraviolet activation, and the activation mode is single and has great application difficulty.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for removing organic matters in water, which can efficiently and conveniently treat refractory organic matters in organic wastewater, converts the refractory organic matters into easily degradable substances by destroying the molecular structure of the refractory organic matters, and has great application potential in the aspect of organic wastewater treatment.

In order to solve the technical problems, the invention can adopt the following technical scheme:

a method for removing organic matters in water comprises the following steps: selecting a water body containing refractory organic matters, adding dithionite and iron ions, adjusting the temperature and the pH value, and treating the refractory organic matters in the water body.

Preferably, the molar ratio of the dithionite to the refractory organic matter is 50-500: 1, the mass ratio of the dithionite to the iron ion is 1: 0.15 to 1.

More preferably, the molar ratio of the dithionite to the refractory organic matter is 100-200: 1, the mass ratio of the dithionite to the iron ion is 1: 0.25 to 1.

Preferably, the temperature is adjusted to be 10-50 ℃.

More preferably, the temperature is adjusted to 30-50 ℃.

Preferably, the pH is adjusted to 3.0-9.0.

More preferably, the pH is adjusted to 3.0 to 7.0.

Preferably, the refractory organic matters in the water body are treated for 0.5-12 h.

Preferably, the organic matters which are difficult to degrade in the water body are treated for 0.5 to 6 hours.

Preferably, the refractory organic compounds are refractory organic pollutants including tetrabromobisphenol A, decabromodiphenyl ether, atrazine (chemical name: 2-chloro-4-diethylamino-6-isopropylamino-1, 3, 5-triazine, CAS number: 1912-24-9), dicamba (chemical name: 3, 6-dichloro-2-methoxybenzoic acid, CAS number: 1918-00-9), and the like.

More preferably, the refractory organic matter is one or more of tetrabromobisphenol A, decabromodiphenyl ether, atrazine and dicamba.

Preferably, the dithionite is dithionite (S) containing dithionite radical₂O₄ ^2-) Salts of (a).

More preferably, the dithionite (S) is contained₂O₄ ^2-) The salt of (A) is sodium hydrosulfite.

Preferably, the iron ions are Fe-containing³⁺Allows partial conversion to ferric hydroxide.

Preferably, the Fe-containing³⁺The salt of (b) is iron salt which is easily dissolved in water, such as ferric sulfate, ferric nitrate, ferric chloride, etc.

More preferably, the Fe-containing compound³⁺The salt includes one or more of ferric sulfate, ferric nitrate and ferric chloride.

Compared with the prior art, the invention has the following beneficial effects:

(1) compared with the prior dithionite advanced reduction technology, the method has the advantages of wide temperature and pH range, no need of controlling dissolved oxygen conditions, low energy consumption, low cost and easy application;

(2) the method is an efficient and convenient treatment technology for the organic water body containing the refractory organic matters, and has great application potential in the aspect of organic wastewater treatment.

Drawings

FIG. 1 is a schematic diagram showing the effect of using iron ions to activate dithionite for degrading tetrabromobisphenol A in example 1;

FIG. 2 is a graph showing the effect of using iron ions to activate dithionite for degrading tetrabromobisphenol A in example 2 at different dithionite dosages;

FIG. 3 is a graph showing the effect of using iron ions to activate dithionite for degrading tetrabromobisphenol A under different iron ion dosage conditions in example 3;

FIG. 4 is a graph showing the effect of using iron ions to activate dithionite for degrading tetrabromobisphenol A in example 4 under different temperature conditions;

FIG. 5 is a graph showing the effect of using iron ions to activate dithionite for degrading tetrabromobisphenol A in example 5 at different pH conditions;

FIG. 6 is a schematic diagram showing the effect of using iron ions to activate dithionite for degrading decabromodiphenyl ether, atrazine and dicamba in example 6;

FIG. 7 is a graph showing the effect of activating dithionite with iron ions on the degradation of decabromodiphenyl ether in example 7 at different pH conditions;

FIG. 8 is a graph showing the effect of using iron ions to activate dithionite for degrading atrazine in example 8;

FIG. 9 is a graph showing the effect of activating dithionite with iron ions on degradation of dicamba in example 9.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1: iron ion activated dithionite for degrading tetrabromobisphenol A

Taking four brown opaque reactors, adding tetrabromobisphenol A solution into the four brown opaque reactors until the concentration of the tetrabromobisphenol A solution reaches 1 mu mol/L, adjusting the pH value to 7 by using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, carrying out the reaction in a constant-temperature reaction tank, adjusting the temperature to 30 ℃, and simultaneously stirring the four reactors at a slow speed to ensure uniform reaction. Reactor 1 was a blank control, and Sodium Dithionite (DTN) solution was added to reactor 2 to a concentration of 100 μmol/L, ferric sulfate solution was added to reactor 3 to a concentration of 100 μmol/L, Sodium dithionite solution was added to reactor 4 to a concentration of 100 μmol/L, and ferric sulfate solution was added to a concentration of 25 μmol/L, respectively. Sampling at 15 min, 30min, 45 min, 60 min and 90min, and detecting the residual concentration of tetrabromobisphenol A by using a high performance liquid chromatograph, wherein the detection result is shown in figure 1.

As can be seen from FIG. 1, the removal rate of dithionite to tetrabromobisphenol A is 47.3% at 90 min; the degradation rate of iron ions to tetrabromobisphenol A is 24.7 percent; after combining iron ions and dithionite, the degradation rate of tetrabromobisphenol A was 88.1%. The iron ions have obvious promotion effect on degrading tetrabromobisphenol A by the dithionite, and probably because the addition of the iron ions can excite a dithionite solution system to generate an iron-containing complex and a high-activity sulfur-containing free radical, so that the dithionite chain reaction is more diversified, and organic matters are efficiently degraded. And the reaction reaches 72.4 percent of removal rate already at 30min, and the reaction is rapid.

Example 2: dithionite dosage

Taking six brown opaque reactors, adding tetrabromobisphenol A solution into the reactors until the concentration reaches 1 mu mol/L, adjusting the pH value to 7 by using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, carrying out the reaction in a constant-temperature reaction tank, adjusting the temperature to 30 ℃, and simultaneously stirring the six reactors at a slow speed to ensure uniform reaction. Sodium Dithionite (DTN) solution and ferric sulfate solution were added to six reactors respectively to make the concentrations of both 20, 50, 100, 200, 400 and 600. mu. mol/L. Sampling at 15 min, 30min, 45 min, 60 min and 90min, and detecting the residual concentration of tetrabromobisphenol A by using a high performance liquid chromatograph, wherein the detection result is shown in figure 1.

As can be seen from fig. 2, the removal rates of tetrabromobisphenol a at 90min were 45.5, 74.7, 85.9, 87.8, 71.1, and 57.1% respectively as the dithionite dosage increased, and it can be seen that the degradation rate increased first and then decreased as the dithionite concentration increased, thereby obtaining a preferred molar ratio of contaminants: dithionite in the ratio of 1: 50 to 500.

Example 3: iron ion dosage

Taking six brown opaque reactors, adding tetrabromobisphenol A solution into the reactors until the concentration reaches 1 mu mol/L, adjusting the pH value to 7 by using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, carrying out the reaction in a constant-temperature reaction tank, adjusting the temperature to 30 ℃, and slowly stirring the six reactors to ensure the uniform reaction. Sodium Dithionite (DTN) solution was added to the five reactors to a concentration of 100. mu. mol/L, while ferric sulfate solution was added to a concentration of 10, 15, 25, 50, 100, 150. mu. mol/L, respectively. Samples were taken at 15, 30, 45, 60 and 90min, and the residual concentration of tetrabromobisphenol A was measured by HPLC, and the results are shown in FIG. 3.

As can be seen from fig. 3, at 90min, as the concentration of iron ions increases, the degradation rates of tetrabromobisphenol a degraded by iron ion activated dithionite are 50.1, 77.2, 88.1, 89.1, 88.8 and 90.5%, respectively, and the degradation rates increase with the increase of the concentration of iron ions, and the molar concentration ratio of iron ions is determined by considering the medicament cost and the like: the iron ions are in the ratio of 1: 0.15 to 1.

Example 4: temperature of

Taking five brown opaque reactors, adding tetrabromobisphenol A solution into the five brown opaque reactors until the concentration of the tetrabromobisphenol A solution reaches 1 mu mol/L, adjusting the pH value to 7 by using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, carrying out the reaction in a constant-temperature reaction tank, respectively adjusting the temperature to 10, 20, 30, 40 and 50 ℃, and slowly stirring the five reactors to ensure the uniform reaction. Sodium dithionite solution was added to the five reactors to a concentration of 100. mu. mol/L, while iron sulfate solution was added to a concentration of 25. mu. mol/L. Samples were taken at 15, 30, 45, 60 and 90min, and the residual concentration of tetrabromobisphenol A was measured by HPLC, and the results are shown in FIG. 4.

As can be seen from FIG. 4, at 90min, the degradation rates of tetrabromobisphenol A degraded by iron ion activated sodium dithionite are respectively 70.5, 79.7, 87.5, 91.1 and 91.5% with the increasing temperature, and the increasing temperature is favorable for the iron ion activated sodium dithionite to degrade tetrabromobisphenol A.

Example 5: pH value

Six brown opaque reactors were taken, tetrabromobisphenol A solution was added thereto to a concentration of 1. mu. mol/L, and the pH in the reactor was adjusted to 7, 3, 5, 7, 9, 11 using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, respectively. The reaction is carried out in a constant-temperature reaction tank, the temperature is adjusted to 30 ℃, and simultaneously, the six reactors are stirred at a low speed to ensure the uniform reaction. Reactor 1 was a blank control, and sodium dithionite solution was added to

reactors

2, 3, 4, 5, and 6 to a concentration of 100. mu. mol/L, while ferric sulfate solution was added to a concentration of 25. mu. mol/L, respectively. Samples were taken at 15, 30, 45, 60 and 90min, and the residual concentration of tetrabromobisphenol A was measured by HPLC, and the results are shown in FIG. 5.

As can be seen from FIG. 5, the degradation rates of tetrabromobisphenol A at 90min with increasing pH were 93.1, 92.5, 88.1, 71.2, and 26.9%, respectively, after combining iron ions and dithionite. It can be seen that acidity, neutrality and slight alkalinity are beneficial to the iron ion activated dithionite for degrading tetrabromobisphenol A, wherein the degradation effect is better when the pH value is 3-9.

Example 6: iron ion activated dithionite for degrading decabromodiphenyl ether, atrazine and dicamba

Taking four brown light-tight reactors, simultaneously adding decabromodiphenyl ether, atrazine and dicamba solution until the concentration reaches 1 mu mol/L, adjusting the pH to 7 by using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, reacting in a constant-temperature reaction tank, adjusting the temperature to 30 ℃, and simultaneously stirring the four reactors at a slow speed to ensure uniform reaction. Reactor 1 was a blank control, and sodium Dithionite (DTN) solution was added to reactor 2 to a concentration of 200. mu. mol/L, ferric chloride solution was added to reactor 3 to a concentration of 100. mu. mol/L, sodium dithionite solution was added to reactor 4 to a concentration of 200. mu. mol/L, and ferric chloride solution was added to a concentration of 100. mu. mol/L, respectively. After 6h of reaction, sampling, and detecting the residual concentrations of decabromodiphenyl ether, atrazine and dicamba by using a high performance liquid chromatograph, wherein the detection result is shown in fig. 6.

As can be seen from FIG. 6, at 6h, the removal rates of dithionite for decabromodiphenyl ether, atrazine and dicamba are respectively 3.9%, 9.1% and 1.6%; the degradation rates of the iron ions to decabromodiphenyl ether, atrazine and dicamba are respectively 25.9, 18.6 and 13.5 percent; after the combination of iron ions and dithionite, the degradation rates of decabromodiphenyl ether, atrazine and dicamba are 77.8, 89.6 and 78.8 percent. The iron ions have obvious promotion effect on the dithionite for degrading decabromodiphenyl ether, atrazine and dicamba.

Example 7: degradation of decabromodiphenyl ether by iron ion activated dithionite under different pH conditions

Eight brown opaque reactors were taken, decabromodiphenyl ether solution was added to the reactor until the concentration reached 1 μmol/L, the pH in

reactors

1, 2, 3 was adjusted to 7 using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, and the pH in reactors 4-8 was adjusted to 3, 5, 7, 9, 11, respectively. The reaction is carried out in a constant-temperature reaction tank, the temperature is adjusted to 30 ℃, and simultaneously, the eight reactors are stirred at a low speed to ensure the uniform reaction. The reactor 1 is a blank control group, sodium hydrosulfite solution is respectively added into the reactor 2 to make the concentration reach 200 mu mol/L, ferric sulfate solution is added into the reactor 3 to make the concentration reach 100 mu mol/L, sodium hydrosulfite solution is added into the

reactors

4, 5, 6, 7 and 8 to make the concentration reach 200 mu mol/L, and ferric sulfate solution is added to make the concentration reach 100 mu mol/L. After 6h of reaction, a sample was taken, and the remaining concentration of decabromodiphenyl ether was measured by HPLC, and the measurement results are shown in FIG. 7.

As can be seen from FIG. 7, the removal rate of the dithionite to decabromodiphenyl ether is 9.8% at 6 h; the degradation rate of iron ions to decabromodiphenyl ether is 21.0 percent; after combining iron ions and dithionite, the degradation rates of decabromodiphenyl ether are 79.8, 80.4, 81.2, 70.5 and 63.1 percent along with the increase of pH. The iron ions have obvious promotion effect on the degradation of the decabromodiphenyl ether by the dithionite, and the neutrality and the acidity are beneficial to the iron ions to activate the dithionite for degrading the decabromodiphenyl ether. Wherein the degradation effect is better when the pH value is 3-7.

Example 8: iron ion activated dithionite for degrading atrazine

Taking four brown opaque reactors, adding atrazine solution into the four brown opaque reactors until the concentration of atrazine solution reaches 1 mu mol/L, adjusting the pH value to 7 by using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, carrying out reaction in a constant-temperature reaction tank, adjusting the temperature to 30 ℃, and simultaneously stirring the four reactors at a slow speed to ensure uniform reaction. Reactor 1 was a blank control, and sodium dithionite solution was added to reactor 2 to a concentration of 50. mu. mol/L, ferric nitrate solution was added to reactor 3 to a concentration of 50. mu. mol/L, sodium dithionite solution was added to reactor 4 to a concentration of 50. mu. mol/L, and ferric nitrate solution was added to a concentration of 50. mu. mol/L, respectively. After the reaction time of 90min, a sample was taken, and the residual concentration of atrazine in the sample was measured by a high performance liquid chromatograph, and the measurement results are shown in fig. 8.

As can be seen from FIG. 8, the removal rate of atrazine by dithionite is 9.4% at 90 min; the degradation rate of iron ions to atrazine is 20.5 percent; after combining iron ions and dithionite, the degradation rate of atrazine was 89.8%. The iron ions have obvious promotion effect on degrading atrazine by dithionite.

Example 9: iron ion activated dithionite for degrading dicamba

Taking four brown light-tight reactors, adding the dicamba solution into the four brown light-tight reactors until the concentration of the dicamba solution reaches 5 mu mol/L, adjusting the pH value to 7 by using 0.1mol/L sulfuric acid and 0.1mol/L sodium hydroxide, carrying out the reaction in a constant-temperature reaction tank, adjusting the temperature to 30 ℃, and simultaneously stirring the four reactors at a slow speed to ensure uniform reaction. Reactor 1 was a blank control, and sodium dithionite solution was added to reactor 2 to a concentration of 500. mu. mol/L, ferric chloride solution was added to reactor 3 to a concentration of 250. mu. mol/L, sodium dithionite solution was added to reactor 4 to a concentration of 500. mu. mol/L, and ferric chloride solution was added to a concentration of 250. mu. mol/L, respectively. After 90min of reaction, a sample was taken, and the remaining concentration of dicamba was measured by HPLC, and the measurement results are shown in FIG. 9.

As can be seen from FIG. 9, at 90min, the removal rate of dicamba by dithionite was 9.5%; the degradation rate of iron ions to dicamba is 33.5%; the degradation rate of dicamba after combination of iron ions and dithionite was 99.1%. The iron ions have obvious promotion effect on the degradation of the dicamba by the dithionite.

The above embodiments are the best mode for carrying out the invention, but the embodiments of the invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the invention should be regarded as equivalent substitutions, and are included in the scope of the invention.

Claims

1. A method for removing organic matters in water is characterized by comprising the following steps: selecting a water body containing refractory organic matters in a brown light-tight reactor, adding dithionite and iron ions, adjusting the temperature and the pH value, and treating the refractory organic matters in the water body; the molar ratio of the dithionite to the refractory organic matter is 50-500: 1, the mass ratio of the dithionite to the iron ion is 1: 0.15 to 1; adjusting the temperature to 10-50 ℃; adjusting the pH value to 3.0-9.0.

2. The method for removing organic substances from water according to claim 1, wherein: and treating the refractory organic matters in the water body for 0.5-12 h.

3. The method for removing organic matters from water according to claim 1 or 2, wherein: the refractory organic matter comprises one or more of tetrabromobisphenol A, decabromodiphenyl ether, atrazine and dicamba.

4. The method for removing organic matters from water according to claim 1 or 2, wherein: the dithionite is dithionite containing dithionite radical (S)₂O₄ ^2-) Salts of (a).

5. The method for removing organic substances from water according to claim 4, wherein: said dithionite (S)₂O₄ ^2-) The salt of (A) is sodium hydrosulfite or potassium hydrosulfite.

6. The method for removing organic matters from water according to claim 1 or 2, wherein: the iron ions are Fe³⁺Salts of (a).

7. The method for removing organic substances from water according to claim 6, wherein: said Fe-containing³⁺The salt includes one or more of ferric sulfate, ferric nitrate and ferric chloride.