CN101560604B - Heavy metal ionic liquid chunk liquid film separating and recycling method - Google Patents

Abstract

The invention discloses a heavy metal ionic liquid chunk liquid film separating and recycling method. The method is implemented according to the following steps: using [BMIM]PF6 or [BEIM]PF6 as a filmsolvent and P507 as a carrier, mixing the ionic liquid and the carrier according to the volume ratio of 0.25-1.0:99.75-99.0 to obtain a liquid film phase; using HNO3 or H2SO4 as a resolution phase; mixing acetic acid and sodium acetate according to the volume ratio of 10-90:90-10 to obtain a buffer solution, and mixing the buffer solution with recycled heavy metallic salt solution according to the volume ratio of 95-85:5-15 to obtain a material liquid phase; adding the liquid film phase into a glass container, when the liquid level of the liquid film phase flows over the margin of the lower opening of a glass tube in the glass container, adding the material liquid phase into the glass container and simultaneously adding the resolution phase into the glass tube, starting a magnetic stirring apparatus to stir the liquid film phase, when the migration rate of the heavy metal ion liquid achieves over 95%, ending the stirring, and then transferring the liquid film phase and the resolutionphase into a separatory funnel for layer separation to obtain the colorless aqueous phase solution of the lower layer as the transferred heavy metal ion liquid.

Description

A kind of heavy metal ionic liquid bulk liquid membrane separation and recovery method

Technical field:

The invention belongs to the technical field of separation and recovery of heavy metals, and in particular relates to a method for separation and recovery of heavy metal ionic liquid bulk liquid membranes.

Background technique:

Since the beginning of the 21st century, worldwide environmental pollution has become increasingly serious. While modern industry provides a variety of materials such as dyes, medicines, fertilizers, cloth, and various performance materials for the development of human society, it also takes the earth we live on Get "disgraced", especially water pollution is particularly serious. As we all know, 70% of our earth is water, and water is the source of all things. Therefore, it is imminent to eradicate water pollution. Heavy metal pollution is one of the most harmful water pollution problems. Heavy metals refer to metals with a specific gravity greater than 5 (generally referring to metals with a density greater than 4.5 grams per cubic centimeter), there are about 45 kinds, generally belonging to transition elements, such as copper, lead, zinc, iron, cobalt, nickel, manganese, cadmium, Mercury, tungsten, molybdenum, gold, silver, etc. Although heavy metals such as manganese, copper, and zinc are trace elements needed for life activities, most heavy metals such as mercury, lead, cadmium, etc. are not necessary for life activities, and all heavy metals exceed a certain concentrations are toxic to humans. Heavy metals enter water bodies through man-made pollution sources such as mining, metal smelting, metal processing and chemical production wastewater, fossil fuel combustion, application of pesticides and fertilizers, and domestic garbage, as well as natural forms such as geological erosion and weathering. Heavy metals in wastewater can be absorbed by soil crops , and stable in nature, difficult to degrade, and can inhibit the growth and development of crops, causing premature aging, reduced yield and even death, and enter the plant through the root system. Heavy metals and their compounds can accumulate and enrich in aquatic organisms and plant tissues, and eventually cause serious harm to human health through bioaccumulation, bioconcentration, and biomagnification in drinking water and food chains. Heavy metal wastewater is a highly polluting type of wastewater. Even if the concentration is small, it can cause harm, and the toxicity has long-term persistence. No matter what treatment method is used, heavy metals cannot be degraded, but can only change their state, or form complexes or chelates with anionic ligands, so that the concentration of heavy metals in water increases and then they are separated from polluted water. In addition, heavy metals are highly toxic, difficult to be metabolized in the environment, easy to be enriched by organisms, and have biomagnification effects. They not only pollute the water environment, but also seriously threaten the survival of humans and aquatic organisms. Water heavy metal pollution has become a global environmental problem. pollution problem.

As far as the current industrial wastewater treatment situation is concerned, many small and medium-sized enterprises have little or no basic investment. One of the important reasons is related to the high investment and low income of enterprises in water treatment facilities. The existing heavy metal separation methods include solvent extraction, precipitation separation, ion exchange and so on. At present, solvent extraction is one of the most widely used methods, but this technology is limited by mass transfer balance, the separation equipment is bulky, the two processes of extraction and stripping need to be carried out in different reactors, the cost is high and the operation is complicated, and organic Solvent, easy to cause pollution to the environment. Although the precipitation separation method is simple, it is not easy to recycle or recycle. The ion exchange method is limited by the exchange capacity of the ion exchanger.

Liquid membrane separation technology is a new type of separation technology that achieves separation, purification and concentration through the selective migration of liquid membranes to the components to be measured in the mixture. Compared with traditional methods, it has many advantages: simple equipment, fast separation speed, High selectivity, low energy consumption and recyclable heavy metal resources. Emulsion liquid membrane method is one of the most widely used liquid membrane separation technologies. However, the emulsified liquid film not only has complicated processes such as milk making and demulsification, but also uses organic solvents and other organic additives, which will cause harm to the environment and human body. Ionic liquid is a kind of ionic compound in liquid state at room temperature, with almost zero volatility, which belongs to "green solvent". The use of ionic liquid in liquid membrane separation has become a new attempt to solve solvent pollution.

Invention content:

The purpose of the present invention is to provide a method for separation and recovery of heavy metal ionic liquid bulk liquid membrane, which solves the problems of complicated operation, low mobility and difficult recycling of organic solvents in the prior art.

The technical scheme adopted in the present invention is a method for separating and recovering heavy metal ionic liquid bulk liquid membranes. The method uses a device, which includes a glass container, and a glass tube with upper and lower openings is vertically arranged in the middle of the glass container. A stirring bar is provided at the bottom of the container, and the stirring bar is connected with an external magnetic stirrer;

Recovery method of the present invention is, utilizes above-mentioned device, implements according to the following steps:

Step 1. Select the ionic liquid [BMIM]PF ₆ or [BEIM]PF ₆ with a purity of 98% as the membrane solvent, select P ₅₀₇ with a purity of 98% as the carrier, and mix the carrier and the ionic liquid at a ratio of 0.25 to 1.0:99.75 to 99.0 The volume ratio is mixed to obtain the liquid film phase;

Step 2. Select 0.5-4mol/L HNO ₃ or H ₂ SO ₄ as the analytical phase;

Step 3. Mix acetic acid and sodium acetate according to the volume ratio of 10-90:90-10 to obtain a buffer solution, and then mix the buffer solution with the heavy metal salt solution to be recovered at a concentration of 2.0-2.5×10 ^-3 mol/L Mix according to the volume ratio of 95～85:5～15, obtain material liquid phase;

Step 4, add the liquid film phase in the glass container, when the liquid level of the liquid film phase overflows the lower opening edge of the glass tube, add the feed liquid phase in the glass container, so that the feed liquid phase floats on the liquid film phase, At the same time, add the analytical phase into the glass tube, turn on the magnetic stirrer to stir the liquid film phase at a speed of 500±50 rpm, so that the heavy metal ions migrate from the feed liquid phase to the analytical phase;

Step 5, take a sample from the feed liquid phase at intervals of 20 to 30 minutes for measurement, and stop stirring when the mobility of the heavy metal ionic liquid reaches more than 95%, and the liquid film phase and the analytical phase are transferred into a separating funnel for stratification, and the lower layer The colorless aqueous phase solution is the ion liquid of the heavy metal to be migrated.

The separation and recovery method of the present invention is simple in ingredients and operation, and has a good effect on the migration and separation of heavy metal elements. The liquid film phase can be recovered, and the ionic liquid can be used as both a solvent and a carrier. Not only is the separation efficiency high, but the film solvent is harmless and can be recycled. It will not cause harm to the environment and human body.

Description of drawings

Fig. 1 is a schematic structural view of a device used in the present invention.

In the figure, 1. glass tube, 2. analytical phase, 3. feed liquid phase, 4. liquid film phase, 5. stirring bar, 6. magnetic stirrer, 7. glass container.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, it is a schematic diagram of the device structure used by the separation and recovery method of the present invention, including a glass container 7, a glass tube 1 with upper and lower openings is vertically arranged in the inside of the glass container 7, and a stirrer 5 is provided at the bottom of the glass container 7, The stirring bar 5 is connected to an external magnetic stirrer 6 . When the device performs migration operation, the liquid film phase 4 is added to the glass container 7, the analytical phase 2 is added to the glass tube 1, and the feed liquid phase 3 is added between the glass tube 1 and the glass container 7.

The heavy metal ionic liquid bulk liquid film separation and recovery method of the present invention utilizes the above-mentioned device to implement according to the following steps:

Step 1. Select the ionic liquid [BMIM]PF ₆ or [BEIM]PF ₆ with a purity of 98% as the membrane solvent, select P ₅₀₇ with a purity of 98% as the carrier, and mix the carrier and the ionic liquid at a ratio of 0.25 to 1.0:99.75 to 99.0 The volume ratio is mixed to obtain the membrane solution, that is, the liquid membrane phase 4.

Step 2, selecting HNO ₃ or H ₂ 8O ₄ with a concentration of 0.5-4 mol/L as the analytical phase 2;

Step 3, mix acetic acid and sodium acetate at a volume ratio of 10-90:90-10 to obtain a buffer solution, and then mix the buffer solution with the heavy metal salt to be recovered at a concentration of 2.0-2.5×10 ^-3 mol/L (such as PbSO ₄ , Cd(NO ₃ ) ₂ or ZnSO ₄ ) solutions are mixed according to the volume ratio of 95-85:5-15 to obtain the material liquid phase 3;

Step 4, add the liquid film phase 4 in the glass container 7, when the liquid level of the liquid film phase 4 overflows the lower opening edge of the glass tube 1, add the material liquid phase 3 in the glass container 7, the material liquid phase 3 floats on the On the liquid film phase 4, add the analytical phase 2 into the glass tube 1 at the same time, turn on the magnetic stirrer 6 to stir the liquid film phase 4 at a speed of 500±50 rpm, so that the heavy metal ions (Pb ²⁺ , Cd ^{2 +} or Zn ²⁺ ) migrates from the feed liquid phase 3 to the analytical phase 2;

Step 5, take a sample from material liquid phase 3 every interval 20 minutes and measure, make chromogenic agent with 4-(2-pyridylazo)-resorcinol sodium (hereinafter referred to as PAR); When heavy metal ion (Pb ²⁺ , Cd ²⁺ or Zn ²⁺ ) when the mobility reaches more than 95%, the stirring is stopped, the liquid film phase 4 and the analytical phase 2 are transferred to the separatory funnel for stratification, and the colorless aqueous phase solution in the lower layer is the heavy metal ion to be migrated (Pb ²⁺ , Cd ²⁺ or Zn ²⁺ ).

For the remaining heavy metal ions (Pb ²⁺ , Cd ²⁺ or Zn ²⁺ ) that have not been stripped out in the upper membrane solution, the liquid membrane phase can be added to an appropriate amount of unused 6mol/L HCl at 300 rpm Stripping is carried out for at least 1 hour with stirring at a speed of 1/min to obtain a small amount of remaining heavy metal ions (Pb ²⁺ , Cd ²⁺ or Zn ²⁺ ). The liquid film phase 4 can be reused, thereby significantly reducing production costs.

The reaction and migration process of heavy metals (lead, cadmium or zinc) in the bulk liquid film system containing carrier ionic liquid can be roughly divided into the following steps:

(1) The metal ions to be migrated in the feed liquid phase diffuse to the interface between the feed liquid phase and the liquid film phase.

(2) At the interface, the metal ions in the feed liquid react chemically with the carrier P ₅₀₇ (expressed as HR) in the membrane phase to generate neutral complex molecules:

In the formula (1), org and f represent the liquid film phase and the feed liquid phase respectively, M _f ⁿ⁺ represents the metal ion in the feed liquid, and (HR) ₂ represents the metal ion mainly existing in dimer form in the nonpolar oil in this paper carrier.

(3) The neutral complex formed by extraction diffuses in the bulk liquid film.

(4) When the neutral complex diffuses to the interface between the liquid film phase and the analytical phase due to the concentration gradient, due to the increase in acidity, a decomplexation reaction occurs and metal ions are released:

In formula (2), s represents the analytical phase.

Metal ions enter the analytical phase from the feed liquid phase, and HR returns to the interface to continue complexing with the metal ions in the feed liquid phase because it is insoluble in water, and so on. In this process, the energy-providing substance is H ⁺ , and its transfer direction is opposite to the migration direction of metal ions. As the mass transfer progresses, the metal ions in the feed liquid phase decrease, while the metal ions in the analytical phase increase. M It is enriched in the analytical phase, so as to achieve the purpose of migration. It can be seen that the migration process of metal ions in the bulk liquid film system containing carrier ionic liquid can be simply described as: the metal ions are first extracted from the feed liquid phase to the liquid film phase, and then the metal ions in the liquid film phase are resolved In another water phase (resolved phase), the migration process of metal ions from the feed liquid phase to the resolved phase is realized.

Embodiment 1: implement according to the following steps and relevant control parameters,

Step 1. Select the ionic liquid [BMIM]PF ₆ with a purity of 98% as the membrane solvent, select P ₅₀₇ with a purity of 98% as the carrier, and then mix the carrier and the ionic liquid at a volume ratio of 0.5:99.5 to obtain a membrane solution , the liquid film phase.

Step 2, select 2.0mol/L _HNO3 as analytical phase 2;

Step 3. Mix acetic acid and sodium acetate at a volume ratio of 65:35 to obtain a buffer solution, and then mix the buffer solution with a concentration of 2.3×10 ^-3 mol/L PbSO ₄ to be recovered at a ratio of 90:10 The volume ratio is mixed to obtain the material liquid phase 3;

Step 4. Add the liquid film phase 4 into the glass container 7, make the liquid surface overflow the edge of the lower opening of the glass tube 1, add the material liquid phase 3 into the glass container 7, and add the analytical phase 2 into the glass tube 1 at the same time, and turn on the magnetic force The agitator 6 stirs the liquid film phase 4 at a speed of 500±50 rpm, so that the heavy metal ion Pb ²⁺ migrates from the feed liquid phase 3 to the analytical phase 2;

Step 5, take samples from the material liquid phase at intervals of 20 minutes, and use PAR as a chromogenic agent; within 120 minutes, the mobility of heavy metal ions Pb ²⁺⁺ reaches 96.7%, and the liquid film phase and the analytical phase are transferred into the separatory funnel Layered, the colorless aqueous solution in the lower layer is the migrated Pb ²⁺ .

Example 2: Select the ionic liquid [BEIM]PF ₆ with a purity of 98% as the membrane solvent, select P ₅₀₇ with a purity of 98% as the carrier, and then mix the carrier and the ionic liquid at a volume ratio of 0.3:99.7 to obtain a liquid Membrane phase 4; use 0.5mol/L HNO ₃ as analytical phase 2; mix acetic acid and sodium acetate at a volume ratio of 90:10 to obtain a buffer solution, and then mix the buffer solution with a concentration of 2.4×10 ^-3 mol/L The solution of Cd(NO ₃ ) ₂ to be recovered is mixed at a volume ratio of 88:12 to obtain the material liquid phase 3; the liquid film phase 4 is added to the glass container 7, so that the liquid level overflows the lower opening edge of the glass tube 1 , the material liquid phase 3 is added to the glass container 7, and the analytical phase 2 is added to the glass tube 1 at the same time, and the magnetic stirrer 6 is turned on to stir the liquid film phase 4 at a speed of 500 ± 50 rpm, so that the heavy metal ion Pb ^{2 +} Migrate from the liquid phase 3 to the analysis phase 2; take samples from the liquid phase every 20 minutes and use PAR as a color developer; within 140 minutes, the mobility of heavy metal ions Pb ²⁺⁺ reaches 95.9%, and the liquid film phase and The analytical phase was transferred to a separatory funnel for stratification, and the colorless aqueous phase solution in the lower layer was the migrated Pb ²⁺ .

Example 3: Select the ionic liquid [BMIM]PF ₆ with a purity of 98% as the membrane solvent, select P ₅₀₇ with a purity of 98% as the carrier, and then mix the carrier and the ionic liquid at a volume ratio of 1:99 to obtain a liquid Membrane phase 4; use 1.0 mol/L H ₂ SO ₄ as analytical phase 2; mix acetic acid and sodium acetate at a volume ratio of 15:85 to obtain a buffer solution, and then mix the buffer solution with a concentration of 2.5×10 ^-3 mol/ L of CuSO to be recovered The solution is mixed at a volume ratio of 93:7 to obtain the material liquid phase 3; _the liquid film phase 4 is added to the glass container 7, so that the liquid level overflows the lower opening edge of the glass tube 1, and the material The liquid phase 3 is added to the glass container 7, and the analytical phase 2 is added to the glass tube 1 at the same time, and the magnetic stirrer 6 is turned on to stir the liquid film phase 4 at a speed of 500 ± 50 rpm, so that the heavy metal ions Cd ²⁺ from the material The liquid phase 3 migrates to the analytical phase 2; samples are taken from the liquid phase every 20 minutes for measurement, and PAR is used as a chromogenic agent; within 120 minutes, the mobility of heavy metal ions Cd ²⁺⁺ reaches 95.1%, and the liquid film phase and the analytical phase are reversed into a separatory funnel to separate layers, and the colorless aqueous solution in the lower layer is the migrated Cd ²⁺ .

Example 4: Select the ionic liquid [BEIM]PF ₆ with a purity of 98% as the membrane solvent, select P ₅₀₇ with a purity of 98% as the carrier, and then mix the carrier and the ionic liquid at a volume ratio of 0.25:99.75 to obtain a liquid Membrane phase 4; use 4.0 mol/L H ₂ SO ₄ as analytical phase 2; mix acetic acid and sodium acetate at a volume ratio of 40:60 to obtain a buffer solution, and then mix the buffer solution with a concentration of 2.5×10 ^-3 mol/ L of ZnSO to be recovered _The solution is mixed at a volume ratio of 85:15 to obtain the material liquid phase 3; the liquid film phase 4 is added to the glass container 7 to make the liquid level overflow the lower opening edge of the glass tube 1, and the material The liquid phase 3 is added to the glass container 7, and the analytical phase 2 is added to the glass tube 1 at the same time, and the magnetic stirrer 6 is turned on to stir the liquid film phase 4 at a speed of 500 ± 50 rpm, so that the heavy metal ions Cd ²⁺ from the material The liquid phase 3 migrates to the analytical phase 2; samples are taken from the liquid phase at intervals of 20 minutes, and PAR is used as a chromogenic agent; the mobility of heavy metal ions Cd ²⁺⁺ reaches 96.3% within 140 minutes, and the liquid film phase and the analytical phase are transferred into Separate the layers in the separatory funnel, and the colorless aqueous solution in the lower layer is the migrated Cd ²⁺ .

Example 5: Select the ionic liquid [BMIM]PF ₆ with a purity of 98% as the membrane solvent, select P ₅₀₇ with a purity of 98% as the carrier, and then mix the carrier and the ionic liquid at a volume ratio of 0.6:99.4 to obtain a liquid Membrane phase 4; use 3.0mol/L H ₂ SO ₄ as analytical phase 2; mix acetic acid and sodium acetate at a volume ratio of 10:90 to obtain a buffer solution, and then mix the buffer solution with a concentration of 2.0×10 ^-3 mol/ L of NiSO to be recovered The solution is mixed at a volume ratio of 95:5 to obtain the material liquid phase 3; _the liquid film phase 4 is added to the glass container 7, so that the liquid level overflows the lower opening edge of the glass tube 1, and the material The liquid phase 3 is added to the glass container 7, and the analytical phase 2 is added to the glass tube 1 at the same time, and the magnetic stirrer 6 is turned on to stir the liquid film phase 4 at a speed of 500 ± 50 rpm, so that the heavy metal ion Zn ²⁺ from the material The liquid phase 3 migrates to the analytical phase 2; samples are taken from the liquid phase at intervals of 20 minutes, and PAR is used as a chromogenic agent; within 120 minutes, the mobility of the heavy metal ion Zn ²⁺⁺ reaches 95.5%, and the liquid film phase and the analytical phase are transferred into Separate the layers in the separatory funnel, and the colorless aqueous solution in the lower layer is the transferred Zn ²⁺ .

Example 6: Select the ionic liquid [BEIM]PF ₆ with a purity of 98% as the membrane solvent, select P ₅₀₇ with a purity of 98% as the carrier, and then mix the carrier and the ionic liquid at a volume ratio of 0.8:99.2 to obtain a liquid Membrane phase 4; use 2.0mol/L H ₂ SO ₄ as analytical phase 2; mix acetic acid and sodium acetate at a volume ratio of 75:25 to obtain a buffer solution, and then mix the buffer solution with a concentration of 2.0×10 ^-3 mol/ L of CoSO to be recovered The solution is mixed at a volume ratio of 90:10 to obtain the material liquid phase 3; _the liquid film phase 4 is added to the glass container 7 so that the liquid level overflows the lower opening edge of the glass tube 1, and the material The liquid phase 3 is added to the glass container 7, and the analytical phase 2 is added to the glass tube 1 at the same time, and the magnetic stirrer 6 is turned on to stir the liquid film phase 4 at a speed of 500 ± 50 rpm, so that the heavy metal ion Zn ²⁺ from the material The liquid phase 3 migrates to the analytical phase 2; samples are taken from the liquid phase at intervals of 20 minutes, and PAR is used as a chromogenic agent; within 140 minutes, the mobility of the heavy metal ion Zn ²⁺⁺ reaches 96.1%, and the liquid film phase and the analytical phase are transferred into Separate the layers in the separatory funnel, and the colorless aqueous solution in the lower layer is the transferred Zn ²⁺ .

In summary, the method of the present invention combines the ionic liquid and the bulk liquid membrane, selects the ionic liquid ([BMIM]PF ₆ or [BEIM]PF) as the membrane solvent and P ₅₀₇ as the carrier to mix to obtain the liquid membrane phase, and H ₂ SO ₄ or HNO ₃ is used as the analytical phase, and acetic acid and sodium acetate are mixed to obtain a buffer solution, and then the buffer solution is mixed with an appropriate concentration of heavy metal salt solution to be recovered to prepare a material liquid phase, and an ionic liquid is used to The method of using a liquid membrane to transport and separate heavy metals has achieved the goals of environmental protection, convenient recycling, high migration efficiency, and low cost.

Claims (1)

1. the ionic liquid chunk liquid film separating and recycling method of a heavy metal species is characterized in that:

This method is used a kind of device, this device comprises Glass Containers (7), the centre of Glass Containers (7) vertically is provided with the Glass tubing (1) of upper and lower opening, and the bottom of Glass Containers (7) is provided with stirrer (5), and stirrer (5) is connected with the magnetic stirring apparatus (6) of outside;

Described recovery method is, utilizes above-mentioned device, implements according to following steps:

Step 1, to choose purity be 98% ionic liquid [BMIM] PF ₆Or [BEIM] PF ₆As membrane solvent, choose purity and be 98% P ₅₀₇As carrier, with carrier and ionic liquid according to 0.25～1.0: 99.75～99.0 volume ratio is mixed, and obtains the liquid film phase;

Step 2, choose the HNO of 0.5～4mol/L ₃Or H ₂SO ₄As separating phase separation;

Step 3, with acetic acid and sodium-acetate according to 10～90: 90～10 volume ratio is mixed, and obtains buffered soln, is 2.0～2.5 * 10 with buffered soln and concentration again ^-3The heavy metallic salt solution to be recycled of mol/L is by 95～85: 5～15 volume ratio is mixed, and obtains the feed liquid phase;

Step 4, liquid film is added in the Glass Containers (7), when the liquid level of liquid film phase covers the lower opening edge of Glass tubing (1), feed liquid is added in the Glass Containers (7), make feed liquid float over mutually on the liquid film phase, simultaneously parsing is added in the Glass tubing (1), unlatching magnetic stirring apparatus (6) stirs liquid film mutually with 500 ± 50 rev/mins rotating speed, makes heavy metal ion separate the phase separation migration in opposite directions from feed liquid;

Step 5, every interval 20～30 minutes are taken a sample mutually from feed liquid and are measured, when reaching 95%, the mobility of heavy metal ion liquid finishes to stir when above, liquid film changes layering in the separating funnel over to separating phase separation, and the colourless aqueous phase solution of lower floor is the heavy metal ion liquid that is moved.

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