WO2019010835A1

WO2019010835A1 - Method for completely removing heavy metal ions in battery plant wastewater by using water-based foam system

Info

Publication number: WO2019010835A1
Application number: PCT/CN2017/104317
Authority: WO
Inventors: 李英; 张凯
Original assignee: 山东大学
Priority date: 2017-07-14
Filing date: 2017-09-29
Publication date: 2019-01-17
Also published as: CN107352680A; CN107352680B

Abstract

A method for completely removing heavy metal ions in battery plant wastewater by using a water-based foam system, the method comprising: adjusting the pH value of wastewater to 4-11, adding a surfactant solution to the wastewater so that the molar ratio of the total number of moles of the surfactant and all heavy metal ions in the wastewater is a proper ratio, and stirring until uniform; introducing the mixed liquid into a foam processor, and introducing foaming gas into the bottom of the foam processor at a certain gas flow rate by means of a quartz sand core, and introducing the generated foam into a foam collector by means of a pipe at the top of the foam processor so as to carry out defoaming and heavy metal recovery treatment until no more foam is generated. The method has simple operation, is low cost, and is suitable for removing various heavy metal ions.

Description

Method for completely removing heavy metal ions in battery plant wastewater by using water-based foam system

Technical field

The invention relates to a method for completely removing heavy metal ions in battery plant wastewater by using a water-based foam system, and belongs to the technical field of environmental chemistry.

Background technique

With the rapid development of the economy, the pollution of water bodies at home and abroad is becoming more and more serious. Among them, the wastewater from the source battery plant containing heavy metals has caused great damage and pollution to water resources, and has great influence on agriculture, industry, human life and the entire ecological balance. Battery plant wastewater not only diverges from soil and air pollution, but also seriously harms the life and health of animals and humans through the food chain. The main sources of wastewater in battery production are wastewater from the cleaning line of the battery production line, pesticide wastewater spilled in the slurry, and wastewater from the ground. It contains a large amount of Pb ²⁺ , Zn ²⁺ , Mn ²⁺ , Hg ^{2 . +} Equal heavy metal ions. These heavy metal ions will not be weakened or disappeared by biodegradation and biological chain circulation, but will be easily enriched and amplified in the biological chain, and will exist in the living body for a long time, and the toxicity of heavy metals is large, so the survival and health of human beings and the environment Safety has had a serious impact and is very harmful. Therefore, efficient and rapid control of water pollution, especially the treatment of polluted wastewater in battery plants, has important environmental effects and far-reaching social significance.

At present, the treatment measures for heavy metal pollution in water can be mainly divided into physical methods, chemical methods, biological methods, etc. according to their mechanism of action. The physical method includes extraction method, adsorption method, ion exchange method, membrane separation, etc., adsorption, concentration and separation without changing the chemical form of heavy metal ions in the wastewater; the method has high efficiency, but has high input cost and large engineering quantity. It is easy to introduce secondary pollution sources and other shortcomings. The biological method mainly removes heavy metal ions in polluted water by the absorption and enrichment of plants and microorganisms. However, due to its long action period and small amount of treatment, plants treated with heavy metal ions are difficult to handle, and the recovery rate of metal ions is low. Short boards also restrict their promotion in industrial applications. The chemical method generally removes heavy metal ions by oxidation, reduction, precipitation, adsorption and inhibition of additives and heavy metal ions. The precipitation method has become the most widely used treatment method in battery plant wastewater treatment because of its good economy and wide application range. The addition of hydroxides, sulfides and chelating agents or complexes which strongly bind to heavy metal ions forms a water-insoluble precipitate with heavy metal ions, thereby purifying the water body. However, for industrial wastewater with complex composition, it is often necessary to adjust the pH several times or to add different types of agents several times in batches due to different precipitation ranges of ions. The operation is complicated, the efficiency is not high, and the treatment of precipitates is difficult. If it is not handled properly, it will be easily reactivated, which will cause secondary pollution and it is difficult to meet national emission standards.

Summary of the invention

In view of the deficiencies of the prior art, the present invention provides a method for completely removing heavy metal ions in battery plant wastewater by using a water-based foam system. The invention adopts a green environmentally-friendly specific surfactant to form a water-based foam, and the selected surfactant has electrical interaction or complexation with heavy metal ions such as Pb ²⁺ and Zn ^{2+ ,} and the surfactant molecules are closely related to the metal cation. After the combination, the amphiphilic adsorption of the surfactant is carried out at the gas-liquid interface, and the heavy metal ions are carried out of the polluted water body by the floating bubbles. The invention has the advantages of simple operation, low cost, low concentration of surfactant, strong adaptability to the complexity of the wastewater of the battery factory, high removal efficiency, suitable for removal of various heavy metal ions, and ensuring by using a green environmentally-friendly surfactant. There is no secondary pollution to the environment.

The technical solution of the present invention is as follows:

A method for completely removing heavy metal ions in battery plant wastewater by using a water-based foam system, including the following steps:

(1) Adjusting the pH of the wastewater to 4-11, adding a pre-formulated surfactant solution to the wastewater. The surfactant solution is added in such a way that the molar ratio of the surfactant to the total moles of all heavy metal ions in the wastewater is ( 1~50): 1, evenly stirred;

(2) introducing the mixture obtained in the step (1) into the foam processor, introducing a foaming gas at the bottom of the foam processor, and controlling the gas flow rate of the foaming gas to be 0.1 to 1.0 L/min to form a foam through the top of the foam processor. The pipe is introduced into the foam collector for defoaming and heavy metal recovery until no foam is produced.

According to the preferred embodiment of the present invention, the surfactant described in the step (1) is a surfactant having at least one negatively charged polar hydrophilic group and a hydrophobic base carbon chain having a length of from 8 to 24, which is negative. The electrodepositive hydrophilic group is a sulfate group, a sulfonic acid group or a carboxylic acid group.

Further preferably, the surfactant further contains an EO, carbonyl or amide group.

According to the preferred embodiment of the present invention, the surfactant is one or more selected from the group consisting of an alkyl sulfate, a fatty alcohol polyoxyethylene ether sulfate, an alkyl carboxylate or an alkyl polyether carboxylate. mixing.

Further preferably, the sulfate group-containing surfactant is sodium lauryl sulfate or a fatty alcohol polyoxyethylene ether sulfate.

Further preferably, the carboxylic acid group-containing surfactant is sodium lauryl carboxylate or sodium tridecyl polyether-4-carboxylate.

According to the present invention, the molar ratio of the surfactant to the total moles of all heavy metal ions in the wastewater in the step (1) is (1 to 30): 1, preferably, the total moles of all heavy metal ions in the surfactant and the wastewater. The molar ratio is (3-15): 1, and most preferably, the molar ratio of the surfactant to the total moles of all heavy metal ions in the wastewater is (5-7):1.

According to a preferred embodiment of the invention, the pH of the wastewater in step (1) is 5-11.

According to the preferred embodiment of the present invention, the flow rate of the blowing gas in the step (2) is 0.1 to 0.7 L/min, and more preferably, the flow rate of the blowing gas is 0.2 to 0.6 L/min.

According to a preferred embodiment of the invention, the blowing gas in step (2) is N ₂ or air.

According to the preferred embodiment of the present invention, the bottom of the foam processor in step (2) is filled with a porous medium quartz sand having a porosity of 35-45%, an average pore throat radius of 0.1-10 μm, and a filling height of 4-7 mm. .

In view of the fact that the concentration of heavy metal ions in some battery plants is extremely high or the mixture is strongly acidic, the wastewater can be pretreated before the foam separation, that is, the pH of the wastewater is adjusted to weak acid or neutral by adding an appropriate amount of alkali solution, and The resulting precipitate was filtered. If the wastewater does not have the above characteristics, no pretreatment is required. After the treatment, the flame atomic spectrophotometer is used. The remaining water body is subjected to measurement of heavy metal ion concentration, and the removal efficiency of heavy metal ions is calculated.

The specific process of the method for removing heavy metal ions in battery plant wastewater by using water-based foam is as follows:

Collecting waste water samples to analyze the types and contents of heavy metal elements, and then according to the molar ratio of heavy metal ions in the wastewater to (1-50):1, and the overall molar concentration after mixing with wastewater is (1-15) mmol. /L requirements, weigh a few surfactants, mixed with an appropriate amount of pure water, at a constant temperature of 25 ~ 40 ° C, stir evenly to form a surfactant solution, then add the treatment agent to the wastewater, mix properly and mix well. The mixture is then introduced into the foam processor while introducing the gas from the foam processor, using a gas flow meter to control the gas flow rate between 0.1 and 1.0 L/min, and introducing the foam into the foam collector through the drainage device at the tip of the foam processor. Defoaming and recovery of heavy metals. Continue to inject gas until no foam is produced.

The principle of the invention:

The invention adopts a specific surfactant which interacts with heavy metal ions such as Pb ²⁺ , Zn ²⁺ , the surfactant molecule and the metal cation are tightly combined in the aqueous solution, and the gas is introduced into the solution, due to the parents of the surfactant The property will be adsorbed on the gas-liquid interface of the bubble, and the foam will be formed by the difference in density, and the heavy metal ions will be carried out of the polluted water body.

The advantages of the invention are as follows:

1. The method of the invention can completely remove the heavy metal ions such as Pb ²⁺ and Zn ²⁺ enriched in the wastewater of the battery plant, and has the advantages of rapid and high efficiency, low input, low energy consumption and simple operation.

2. The method of the invention is applied to the treatment of wastewater of a battery factory contaminated by heavy metal ions such as Pb ²⁺ , Zn ²⁺ , the amount of surfactant is small, the removal efficiency of heavy metal ions is high, and the Pb ²⁺ and Zn ²⁺ in the wastewater are high. The removal efficiency can reach more than 99.8%, which does not cause secondary pollution to the water body, and achieves the effect of completely removing heavy metal ions.

3. The method of the invention can be directly applied to various battery plant wastewaters polluted by heavy metal ions to achieve an ideal removal efficiency and meet national emission standards.

4. The method of the present invention, which is detached from the foam of the aqueous phase, can be recovered after treatment, and the surfactant can also be recycled.

The removal efficiency was calculated by measuring the concentration of heavy metal ions in the water before and after the treatment. The removal efficiency η = (C ₁ - C ₂ ) / C ₁ , where C ₁ is the concentration of heavy metal ions before treatment, and C ₂ is the concentration of residual heavy metal ions after the end of foaming. Factors influencing the removal efficiency include the type of hydrophilic group of the surfactant, the molar ratio of surfactant to metal ion, the gas flow rate, the concentration of the surfactant solution, and the bulk pH.

DRAWINGS

Figure 1 is a graph showing the effect of gas flow rate on the removal efficiency of Pb ²⁺ and Zn ²⁺ .

Detailed ways

The present invention will be further described below in conjunction with the embodiments, but is not limited thereto.

Example 1:

A method for completely removing heavy metal ions in battery plant wastewater by using a water-based foam system, wherein the concentration of Pb ²⁺ in the wastewater to be treated is 0.5 mmol/L, the solution is weakly acidic, and the pH is 4, and the steps are as follows:

(1) The wastewater is weakly acidic and does not require pretreatment. Sodium dodecyl sulfate is dissolved in water to prepare a solution of sodium lauryl sulfate, which is added to the wastewater. After mixing, the overall concentration of sodium lauryl sulfate in the wastewater is 3.5 mmol. / L, the molar ratio of sodium lauryl sulfate to Pb ²⁺ is 7:1;

(2) The mixture obtained in the step (1) is introduced into a foam processor filled with porous media quartz sand, and N _{2 is} introduced into the bottom of the foam processor at a gas flow rate of 0.1 L/min, and foaming is continued until it cannot be produced. Up to the foam, the foam is introduced into the foam collector through a pipe at the top of the treatment column for use as a surfactant and heavy metal ion recovery. Then, the treated wastewater was analyzed by heavy atomic ion concentration spectrophotometer, and the removal efficiency η=(C ₁ -C ₂ )/C _{1 was} calculated. The results showed that the efficiency of Pb ²⁺ removal was 99.8%. .

Example 2:

A method for completely removing heavy metal ions in battery plant wastewater by using water-based foam system, wherein the concentration of Pb ²⁺ and Zn ^{2+ in the} wastewater to be treated is 0.2 mmol/L, 0.3 mmol/L, and the solution is neutral, and the pH is 6.82. ,Proceed as follows:

(1) The wastewater is neutral, no pretreatment is required, and the sodium tridecyl polyether-4-carboxylate is dissolved in water to prepare a solution of sodium tridecyl polyether-4-carboxylate, which is added to the wastewater and mixed uniformly in the wastewater. The overall concentration of sodium tridecyl polyether-4-carboxylate is 2.5 mmol/L, and the molar ratio of sodium tridecyl polyether-4-carboxylate to the total moles of Pb ²⁺ and Zn ²⁺ is 5: 1;

(2) The mixture obtained in the step (1) is introduced into a foam processor filled with a porous medium quartz sand, and N _{2 is} introduced into the bottom of the foam processor at a gas flow rate of 0.2 L/min, and foaming is continued until it cannot be produced. Up to the foam, the foam is introduced into the foam collector through a pipe at the top of the treatment column for use as a surfactant and heavy metal ion recovery. Then, the treated wastewater is analyzed by heavy atomic ion concentration using a flame atomic spectrophotometer, and the removal efficiency η=(C ₁ -C ₂ )/C _{1 is} calculated. The results show that the method removes Pb ²⁺ and Zn ²⁺ . The efficiency can reach more than 99.9%.

Example 3:

A method for thoroughly removing heavy metal ions in battery plant wastewater by using a water-based foam system, wherein the concentration of Pb ²⁺ and Zn ²⁺ after dilution of the treated wastewater is 0.3 mmol/L, 0.7 mmol/L, the solution is weakly acidic, and the pH is 5, the steps are as follows:

(1) The wastewater is weakly acidic, no pretreatment is required, and the sodium tridecyl polyether-4-carboxylate is dissolved in water to prepare a solution of sodium tridecyl polyether-4-carboxylate, which is added to the wastewater, and uniformly mixed in the wastewater. The overall concentration of sodium tridecyl polyether-4-carboxylate is 5 mmol/L, and the molar ratio of sodium tridecyl polyether-4-carboxylate to the total moles of Pb ²⁺ and Zn ²⁺ is 5:1. ;

(2) The mixture obtained in the step (1) is introduced into a foam processor filled with a porous medium quartz sand, and N _{2 is} introduced into the bottom of the foam processor at a gas flow rate of 0.2 L/min, and foaming is continued until it cannot be produced. Up to the foam, the foam is introduced into the foam collector through a pipe at the top of the treatment column for use as a surfactant and heavy metal ion recovery. Then, the treated wastewater is analyzed by heavy atomic ion concentration using a flame atomic spectrophotometer, and the removal efficiency η=(C ₁ -C ₂ )/C _{1 is} calculated. The results show that the method removes Pb ²⁺ and Zn ²⁺ . The efficiency is 99.8%.

Example 4:

A method for completely removing heavy metal ions in battery plant wastewater by using a water-based foam system, wherein the concentrations of Pb ²⁺ and Zn ^{2+ in the} wastewater to be treated are 1.0 mmol/L and 1.5 mmol/L, respectively, and the solution is strongly acidic and has a pH of 1.2. Proceed as follows:

(1) The wastewater is strongly acidic. The wastewater from the battery plant is pretreated, 1mmol/L sodium hydroxide solution is prepared, the wastewater is added to the wastewater to adjust the wastewater to neutrality, the pH is 7, the precipitate is filtered, and the filtrate is retained to measure the heavy metal ions again. Concentration; sodium tridecyl polyether-4-carboxylate and sodium lauryl sulfate dissolved in water to prepare a solution into the wastewater, mixed uniformly after the tridecyl polyether-4-carboxylate and ten in the wastewater The total concentration of sodium dialkyl sulfate is 12 mmol/L, and the molar ratio of sodium tridecyl polyether-4-carboxylate and sodium lauryl sulfate to the total moles of Pb ²⁺ and Zn ²⁺ is 5:1. ;

(2) The mixture obtained in the step (1) is introduced into a foam processor filled with a porous medium quartz sand, and N _{2 is} introduced into the bottom of the foam processor at a gas flow rate of 0.3 L/min, and foaming is continued until it cannot be produced. Up to the foam, the foam is introduced into the foam collector through a pipe at the top of the treatment column for use as a surfactant and heavy metal ion recovery. Then, the treated wastewater is analyzed by heavy atomic ion concentration using a flame atomic spectrophotometer, and the removal efficiency η=(C ₁ -C ₂ )/C _{1 is} calculated. The results show that the method removes Pb ²⁺ and Zn ²⁺ . The efficiency is above 99.8%.

Comparative example

A method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system as described in Example 1, except that:

Comparative Example 1: The gas flow rate was 0.01 L/min.

Comparative Example 2: The gas flow rate was 0.05 L/min.

Comparative Example 3: The gas flow rate was 0.08 L/min.

Comparative Example 4: The gas flow rate was 1.2 L/min.

Comparative Example 5: The gas flow rate was 1.4 L/min.

Comparative Example 6: The gas flow rate was 1.6 L/min.

Comparative Example 7: The gas flow rate was 2.0 L/min.

Experimental example:

The effects of the foaming gas flow rates on the removal efficiency of Pb ²⁺ and Zn ²⁺ in the treatment methods of Examples 1 to 4 and Comparative Examples 1 to 7 above are shown in Fig. 1. (The surfactant concentration is 3.5mmol/L, the lead ion and zinc ion concentrations are each 0.5mmol/L, and the solution pH is 6)

Claims

A method for completely removing heavy metal ions in battery plant wastewater by using a water-based foam system, including the following steps:

(1) Adjusting the pH of the wastewater to 4-11, adding a pre-formulated surfactant solution to the wastewater. The surfactant solution is added in such a way that the molar ratio of the surfactant to the total moles of all heavy metal ions in the wastewater is ( 1~50): 1, evenly stirred;

(2) introducing the mixture obtained in the step (1) into the foam processor, introducing a foaming gas at the bottom of the foam processor, and controlling the gas flow rate of the foaming gas to be 0.1 to 1.0 L/min to form a foam through the top of the foam processor. The pipe is introduced into the foam collector for defoaming and heavy metal recovery until no foam is produced.
The method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system according to claim 1, wherein the surfactant in the step (1) is at least one negatively charged polar hydrophilic group. A surfactant having a hydrophobic chain carbon chain length of from 8 to 24, wherein the negative electrode hydrophilic group is a sulfate group, a sulfonic acid group or a carboxylic acid group.
A method of completely removing heavy metal ions from battery plant wastewater using a water-based foam system according to claim 2, wherein said surfactant further contains EO, carbonyl or amide groups.
The method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system according to claim 2, wherein the surfactant is an alkyl sulfate, a fatty alcohol polyoxyethylene ether sulfate, or an alkyl group. One or a mixture of two or more of a carboxylate or an alkylpolyether carboxylate is optionally mixed.
The method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system according to claim 2, wherein the sulfate-containing surfactant is sodium lauryl sulfate or a fatty alcohol polyoxyethylene ether sulfate. .
The method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system according to claim 2, wherein the carboxylic acid group-containing surfactant is sodium lauryl carboxylate or tridecyl alcohol polyether. Sodium 4-carboxylate.
The method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system according to claim 1, wherein the molar ratio of the total moles of all heavy metal ions in the surfactant to the wastewater in the step (1) is (1). ～30): 1, preferably, the molar ratio of surfactant to total number of moles of all heavy metal ions in the wastewater is (3-15): 1, most preferably, the total moles of all heavy metal ions in the surfactant and wastewater The molar ratio is (5-7): 1, and the pH of the wastewater is 5-11.
The method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system according to claim 1, wherein the gas flow rate of the foaming gas in the step (2) is 0.1 to 0.7 L/min, and further preferably, The bubble gas flow rate is 0.2 to 0.6 L/min.
The method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system according to claim 1, wherein the foaming gas in the step (2) is N 2 or air.
The method for completely removing heavy metal ions in a battery plant wastewater by using a water-based foam system according to claim 1, wherein the bottom of the foam processor in the step (2) is filled with a porous medium quartz sand, and the porous medium quartz sand porosity It is 35-45%, the average pore throat radius is 0.1-10 μm, and the filling height is 4-7 mm.