CN107879388A - A kind of method using heavy metal ion in particle stabilized foam quickly cleaning water - Google Patents

Abstract

The invention discloses a method for rapidly purifying heavy metal ions in water by using particle-stabilized foam, which comprises the following steps: 1) preparing a salt solution after mixing and reacting fatty acid with an alkali solution; 2) adjusting the pH value of waste water containing heavy metal ions To 4‑8, add the salt solution prepared in step 1) into the wastewater, stir vigorously to form a solid foam, and carry the heavy metal ions in the wastewater into the solid foam to realize the removal of the heavy metal ions in the wastewater. The method utilizes the heavy metal ions in the waste water to be directly combined with the purifying agent to generate solid foam, which can purify and remove these ions together, has simple and fast operation, and has wide-spectrum applicability to most heavy metal ion pollutants in water.

Description

A method for rapid purification of heavy metal ions in water using particle-stabilized foam

technical field

The invention belongs to the field of waste water treatment, in particular to a method for rapid purification of heavy metal ions in water by particle-stabilized foam (solid foam method).

technical background

With the development of industrialization, resource and environmental issues have increasingly become the focus of social attention. The chemical industry and metal smelting industry will produce a large amount of wastewater in the production process, which must be purified and treated before being discharged after reaching the standard. In wastewater, the pollution of heavy metal ions is a very serious problem. Therefore, it is very important for the removal and recovery of heavy metal ions in wastewater.

At present, there are two types of purification methods for wastewater containing heavy metal ions: chemical methods and physical methods. Chemical method is the main method at present, including chemical precipitation method and electrolysis method, which is suitable for wastewater containing high concentration of heavy metal ions. The chemical precipitation method converts metal ions into insoluble substances and removes them through operations such as filtration. The concentration of residual ions after removal by this method is often high, and the separation and treatment of precipitated substances is relatively difficult. Electrolysis is mainly used for electroplating wastewater treatment, but the problem is that metal ions cannot be completely removed.

Physical methods mainly include solvent extraction separation, ion exchange method, membrane separation technology and adsorption method. The solvent extraction method uses the extractant to combine with heavy metal ions through complexation. In this method, the solvent is lost during the extraction process and the energy consumption in the regeneration process is relatively large. The ion exchange method uses ion exchange resins, chelating agents, etc. to exchange metal ions. The disadvantage is that the chemical properties of the ion exchanger are unstable, easy to fail, and the regeneration operation cost is relatively high. Membrane separation technology uses a special semi-permeable membrane to separate or concentrate solvents and solutes under the action of external pressure, including electrodialysis and diaphragm electrolysis, which have problems such as electrode polarization, scaling, and corrosion during operation. , limiting its application. The adsorption method uses the adsorption of porous solid substances to remove heavy metal ions in water. The traditional adsorbent in the adsorption method is activated carbon. Although activated carbon has strong adsorption capacity and high removal rate, its regeneration efficiency is low and its price is expensive, so its application is limited. In recent years, a series of adsorption materials have been gradually developed, such as chitosan and its derivatives, modified sepiolite, montmorillonite, etc., but there has been no good solution to the problem of its reuse.

Therefore, finding a fast, efficient, low-cost, and simple-to-operate method for removing and recovering heavy metal ions in wastewater is of great significance for the environmental problems of wastewater discharge and the full utilization of resources for metal recovery in wastewater.

Contents of the invention

In order to solve the technical problems in the prior art, the purpose of the present invention is to provide a method for rapidly purifying heavy metal ions in water by using particle-stabilized foam. The method utilizes the heavy metal ions in the waste water to be directly combined with the purifying agent to generate solid foam, which can purify and remove these ions together, has simple and fast operation, and has wide-spectrum applicability to most heavy metal ion pollutants in water.

In order to solve the above technical problems, the technical solution of the present invention is:

A method for rapidly purifying heavy metal ions in water using particle-stabilized foam, comprising the steps of:

1) After fatty acid and alkali solution are mixed and reacted, salt solution is prepared;

2) Adjust the pH value of the wastewater containing heavy metal ions to 4-8, add the salt solution prepared in step 1) into the wastewater, stir vigorously to form a solid foam, and carry the heavy metal ions in the wastewater into the solid foam to realize the waste water removal of heavy metal ions.

The fatty acid salt combines with the heavy metal ions to be extracted to form solid foam that floats on the surface of the wastewater. The solid foam can be separated from the wastewater by simple filtration, and the operation is simple and the removal speed is fast.

In the process of treating wastewater containing heavy metal ions, no other organic solvents are required, and the organic extractant will not be lost, nor will it cause secondary pollution to the wastewater.

The extraction process of heavy metal ions in wastewater does not require complicated extraction process, just simply mix and stir the water phase. The whole process is very fast and can be completed within a few minutes. Compared with the traditional liquid-liquid extraction method, it requires a longer contact time. On balance, the method of the present invention saves considerable processing time. Under suitable conditions, the removal rate of Pb ²⁺ , Cd ²⁺ , Hg ²⁺ , Cr ³⁺ , Cu ²⁺ , Ni ²⁺ , Zn ²⁺ ions can be higher than 99%, and Cd ²⁺ can reach 99.96%. The residue in the medium is less than 0.5ppm, which meets the national emission requirements. Fatty acid is a common chemical raw material with low price, and the cost of wastewater treatment is low.

Preferably, the above method further includes the step of separating the foam from the waste water. The heavy metal ions in the wastewater can be removed by separating the foam; the regeneration of fatty acids can be realized by treating the foam without waste of extractant.

Preferably, in step 1), the alkaline solution is NaOH solution or KOH solution. The strong alkaline solution can easily realize the full reaction with the fatty acid to generate the corresponding salt.

Further preferably, in step 1), the molar ratio of fatty acid to base is 1:1.

Preferably, in step 1), the fatty acid is C _n H _2n+1 COOH (n=7, 8, 9, 10, 11, 12, 13, 15, 17); or C _n H _2n-1 COOH ( n=17).

Preferably, in step 1), the concentration of fatty acid salt in the salt solution is 10-50mM.

Preferably, in step 2), the heavy metal contained in the wastewater containing heavy metal ions is Pb ²⁺ , Cd ²⁺ , Hg ²⁺ , Cr ^{3+ ,} Cu ²⁺ , Ni ²⁺ or Zn ²⁺ .

Preferably, in step 2), the pH value of the wastewater containing heavy metal ions is adjusted to 5-7.

Preferably, in step 2), the volume ratio of the salt solution to the waste water is 1:1-1:5.

Preferably, the above method further includes the step of treating the solid foam to recover fatty acid.

Further preferably, the method for treating the solid foam is: acidifying the separated solid foam with an acid to obtain insoluble fatty acid solids or floating fatty acid oil phase, and the fatty acid can be recovered by liquid separation or filtration.

Even more preferably, the acid is a strong acid such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid and the like.

More preferably, the organic solvent is chloroform, diethyl ether or petroleum ether.

Even more preferably, the molar ratio of the added acid to fatty acid salt is 2:1 for removing divalent heavy metal ions; or the molar ratio of added acid to fatty acid salt is 3:1 for removing trivalent heavy metal ion.

The beneficial technical effect of the present invention is:

1) The removal speed is fast. After the cleaning agent is added, stir to form foam immediately, floating on the top of the liquid surface.

2) The separation process is simple. The upper solid foam can be taken out directly without filtering or liquid separation.

3) High removal rate. Under suitable conditions, the removal rate of Pb ²⁺ , Cd ²⁺ , Hg ²⁺ , Cr ³⁺ , Cu ²⁺ , Ni ²⁺ , Zn ²⁺ ions can be higher than 99%, and Cd ²⁺ can reach 99.96%. The residue in the medium is less than 0.5ppm, which meets the national emission requirements.

4) Low cost. Fatty acid is a common chemical raw material with low price. And it can be reused, and the regeneration process is simple and convenient.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application, and do not constitute improper limitations to the present application.

Figure 1 is a photograph of a sample after mixing sodium laurate solution with aqueous solutions containing different types of heavy metal ions in reaction amounts (the metal ions are Cd ²⁺ , Pb ²⁺ , Hg ²⁺ , and Cr ³⁺ from left to right).

Figure 2 is an optical micrograph of the foam sample formed by sodium laurate and heavy metal ions, the metal ions are (a) Cd ²⁺ , (b) Pb ²⁺ , (c) Hg ²⁺ , (d) Cr ³⁺ .

Fig. 3 is a scanning electron micrograph (SEM) of a foam sample formed by sodium laurate and heavy metal ions, the metal ions are (a) Cd ²⁺ , (b) Pb ²⁺ .

Detailed ways

It should be pointed out that the following detailed description is exemplary and intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

Example 1:

Add nonanoic acid to 40mM NaOH solution, wherein the molar ratio of nonanoic acid to NaOH is 1:1 to form a clear solution; add the solution to waste water containing cadmium ions (Cd ²⁺ ), adjust the pH to 7.0±0.5, and vigorously Stir; the upper layer of foam is separated, and the Cd ²⁺ in the wastewater is removed, and the removal rate is 99.96%.

Example 2:

Mix lauric acid with 20mM NaOH solution, wherein the molar ratio of lauric acid to NaOH is 1:1 to form a clear solution; add the corresponding amount of sodium laurate solution containing Cd ²⁺ , Pb ²⁺ , Hg ²⁺ , Cr ³⁺ The pH in the waste water was adjusted to 7.0±0.5, 5.5±0.5, 6.0±0.5, 6.0±0.5, and the solid foam was formed by vigorous stirring; the upper layer of foam was separated, and the metal ions in the waste water were recovered and removed, and the removal rate was 99.56 %, 99.26%, 95.54%, 98.57%. The solid foam formed in the present embodiment is as shown in Figure 1. It can be seen that sodium laurate combines with these metal ions to form a solid foam floating above the liquid phase. Due to the presence of a large amount of air in the foam, its density is small and the floating Above the liquid surface, the solid foam volumes formed by the same amount of sodium laurate are not exactly the same, indicating that the size distribution of the foam formed by different ions is somewhat different.

Figure 2 is an optical micrograph of the foam sample formed by sodium laurate and heavy metal ions, the metal ions are (a) Cd ²⁺ , (b) Pb ²⁺ , (c) Hg ²⁺ , (d) Cr ³⁺ . It can be observed that the size of the solid foam formed by sodium laurate and different metal ions is polydisperse, and the scale is in the range of 20–400 μm. The size distribution of the foam is also different for different metal ions. For example, Cd ²⁺ and Cr ³⁺ are easier to Larger foams are formed, while Pb ²⁺ and Hg ²⁺ tend to form small foams.

Fig. 3 is a scanning electron micrograph (SEM) of a foam sample formed by sodium laurate and Cd ²⁺ (a) and Pb ²⁺ (b) ions. SEM photos show that the foam is approximately spherical in shape, and its wall is formed by solid particles of laurate, and the particles formed with Cd ²⁺ are needle-shaped particles, while the particles formed with Pb ²⁺ are irregular in shape and approximately spherical .

Example 3:

Mix oleic acid with 20mM KOH solution, wherein the molar ratio of oleic acid to KOH is 1:1 to form a clear solution; add this solution to the wastewater containing mercury ions (Hg ²⁺ ), adjust the pH to 5.0±0.5, and stir vigorously ; The upper layer of foam is separated, and the Hg ²⁺ in the wastewater is recovered and removed, and the removal rate is 99.60%.

Example 4:

Mix nonanoic acid with 40mM NaOH solution, wherein the molar ratio between nonanoic acid and NaOH is 1:1 to form a clear solution; add this solution to the wastewater containing chromium ions (Cr ³⁺ ), adjust the pH to 7.0±0.3, and stir vigorously ; The upper layer of foam is separated, and the Cr ³⁺ ions in the waste water are recovered and removed, and the removal rate is 98.60%.

Example 5:

Add a certain amount of water to the solid foam formed by the separated pelargonic acid and heavy metal ions; add the reaction amount of hydrochloric acid, stir, and stand still to separate into oil/water two phases; separate the upper phase to recover pelargonic acid.

Embodiment 6:

Add a certain amount of water to the solid foam formed by the separated lauric acid and heavy metal ions; add the reaction amount of acetic acid, stir to produce insoluble matter; filter and recover to obtain lauric acid.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (10)

1. A kind of 1. method using heavy metal ion in particle stabilized foam quickly cleaning water, it is characterised in that：Including as follows Step：

   1) by after aliphatic acid and aqueous slkali hybrid reaction, salting liquid is made；

   2) pH value of heavy metal ion-containing waste water is adjusted to 4-8, the salting liquid being prepared in step 1) is added in waste water, it is acute Strong stirring forms solid foam, and the heavy metal ion in waste water is carried into solid foam, realizes heavy metal ions in wastewater Removal.
2. 2. according to the method for claim 1, it is characterised in that：In step 1), the aqueous slkali is that NaOH solution or KOH are molten Liquid；

   Preferably, the aliphatic acid is C_nH_2n+1COOH, n=7,8,9,10,11,12,13,15,17；

   Or C_nH_2n-1COOH, n=17.
3. 3. according to the method for claim 1, it is characterised in that：In step 1), the mol ratio of aliphatic acid and alkali is 1:1；

   Preferably, in step 1), the concentration of soap is 10-50mM in the salting liquid.
4. 4. according to the method for claim 1, it is characterised in that：In step 2), the weight that contains in heavy metal ion-containing waste water Metal is Pb²⁺、Cd²⁺、Hg²⁺、Cr³⁺、Cu²⁺、Ni²⁺Or Zn²⁺；

   Preferably, the pH value of heavy metal ion-containing waste water is adjusted to 5-7；

   Preferably, in step 2), the volume ratio of salting liquid and waste water is 1:1-1:5.
5. 5. according to the method for claim 1, it is characterised in that：The step of also including separating foam with waste water.
6. 6. according to the method for claim 5, it is characterised in that：Also include handling the solid foam of separation, reclaim The step of aliphatic acid.
7. 7. according to the method for claim 6, it is characterised in that：The method handled the solid foam is：It will divide The solid foam acid acidifying separated out obtains insoluble fatty-acid solid or the aliphatic acid oil phase of floating, and liquid separation or filtering can return Receive aliphatic acid.
8. 8. according to the method for claim 7, it is characterised in that：The acid is hydrochloric acid, sulfuric acid, nitric acid or acetic acid.
9. 9. according to the method for claim 7, it is characterised in that：The organic solvent is chloroform, ether or petroleum ether.
10. 10. according to the method for claim 8, it is characterised in that：The acid of addition is 2 with the mol ratio of soap:1, use In removing divalent heavy metal ions；Or the mol ratio of the acid added and soap is 3:1, for remove trivalent heavy metals from Son.