A porous hydrotalcite ceramic membrane and a preparation method and application thereof

Abstract

The application provides a porous hydrotalcite ceramic membrane and a preparation method and application thereof, and the method uses a mixture of hydrotalcite and zirconium hydrogen phosphate as raw materials, mixes the raw materials with a binder, and forms a ceramic membrane embryo through plastic compression molding, then the ceramic membrane embryo is calcined in an air atmosphere to form a porous hydrotalcite ceramic membrane, and the porous hydrotalcite ceramic membrane is modified by being calcined in a water vapor-rich condition to form a surface hydroxyl-rich porous hydrotalcite ceramic membrane. The ceramic membrane can effectively remove chlorine ions and heavy metals in simulated wastewater rich in chlorine ions and heavy metals after the flocculant is added into the simulated wastewater and the wastewater is stirred. The method has high removal rate, and the raw materials are low in price and simple in preparation process of the hydrotalcite ceramic membrane. The heavy metal elements can be recycled by reverse flushing of the used ceramic membrane, the used ceramic membrane is calcined in a water vapor-rich condition, and low-concentration HCl solution can be obtained by passing tail gas through water, so that certain economic benefits are obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wastewater purification, in particular to a porous hydrotalcite ceramic membrane and a preparation method and application thereof. BACKGROUND

[0002] Heavy metal and chloride wastewater is generally derived from metal smelting and processing, petroleum chemical industry, printing and dyeing, salt making, thermal power and other industries. Such wastewater not only corrodes equipment and causes safety hazards, but also pollutes surface water and groundwater. At the same time, heavy metals are an important and valuable resource, and have high value. Therefore, how to effectively treat heavy metal pollution in water bodies, protect human health and the ecological environment, and recycle and utilize heavy metals to alleviate the pressure on resources and the environment in China is an important issue that needs to be addressed at present.

[0003] Wastewater generated by different industries and different enterprises differs in heavy metal and chloride concentration, drainage volume, pH value and other aspects, and even differs greatly. Therefore, a single treatment mode (technology, parameters) cannot be universally applicable. Most single wastewater treatment technologies in China cannot independently achieve wastewater recycling or even meet the standards, and the cost is high, which cannot meet the demand for domestic wastewater treatment.

[0004] The most widely used heavy metal wastewater treatment technology in China at present is chemical precipitation, followed by chelating agent chelation. Chemical precipitation uses a variety of reagents, such as NaOH, CaO, and polymeric ferric sulfate. These reagents are usually inexpensive and have relatively low costs, with a treatment cost of about 6 yuan per ton of water, but further deep treatment is still needed. Chelating agent chelation is superior to chemical precipitation in terms of wastewater treatment effect, with the characteristics of less use, good heavy metal treatment effect, and less secondary pollution such as sediment, but the chelating agent used has a high price, so the overall popularity is lower than that of chemical precipitation. At the same time, whether it is chemical precipitation or chelating agent chelation, the separation of heavy metal ions from water requires long-time standing and precipitation, greatly increasing the time cost. Common chloride wastewater treatment technologies include chemical precipitation, evaporation concentration, membrane separation, adsorption, and electrolysis. However, chemical precipitation needs to improve the utilization efficiency of its reagents and reduce raw material consumption; evaporation concentration has high energy consumption; membrane separation and adsorption require high chloride ion concentration; and electrolysis produces chlorine gas, causing safety hazards. Finally, the current heavy industrial wastewater treatment of heavy metals and chlorides requires segmented treatment, increasing the industrial disposal cost. SUMMARY

[0005] The present application provides a porous hydrotalcite ceramic membrane and a preparation method and application thereof.

[0006] A preparation method of a porous hydrotalcite ceramic membrane, the method comprising the following steps:

[0007] (1) mix hydrotalcite powder with zirconium hydrogen phosphate to obtain a mixed powder, then dissolve a binder in water and mix the mixed powder to obtain a mixture;

[0008] (2) form the mixture obtained in step (1) by plastic compression, dry and then calcine, and then treat at 200-350 DEG C for 2-4 h in a water vapor concentration of 50-80% to form a final product.

[0009] In the technical scheme of the present application: the hydrotalcite is one of magnesium-aluminum hydrotalcite, zinc-aluminum hydrotalcite and copper-aluminum hydrotalcite; the binder is one of polyethylene oxide (PEO) and carboxymethyl cellulose (CMC).

[0010] In the technical scheme of the present application: the mass ratio of the binder, zirconium hydrogen phosphate and hydrotalcite powder in step (1) is (1.5-3):(30-40):100.

[0011] In the technical scheme of the present application: the calcination in step (2) is performed in air, the calcination temperature is 800-900 DEG C, and the calcination time is 8-16 h.

[0012] A porous hydrotalcite ceramic membrane is prepared by the above method.

[0013] In the technical scheme of the present application, the porous hydrotalcite ceramic membrane prepared by the above method is used for removing chlorine ions and heavy metals in heavy chemical industry wastewater.

[0014] The present application has the following advantages:

[0015] (1) The hydrotalcite has the function of adsorbing chlorine ions, and the modification of the hydrotalcite ceramic membrane by water vapor at high temperature makes the surface of the hydrotalcite ceramic membrane rich in hydroxyl groups, which can further improve the adsorption performance;

[0016] (2) After the hydrotalcite powder is prepared into a ceramic membrane, it can adsorb chlorine ions and filter flocculation and precipitation of heavy metals at the same time, so as to achieve the effect of removing chlorine ions and heavy metals at the same time;

[0017] (3) The flocculant can form a precipitate with heavy metals of high concentration, but the removal effect of trace heavy metal ions is not significant, and the addition of zirconium hydrogen phosphate in the hydrotalcite ceramic powder can adsorb heavy metal ions by using the interlayer spacing of zirconium hydrogen phosphate, so as to make the heavy metal emission meet the standard;

[0018] (4) The hydrotalcite ceramic membrane treated with the wastewater can remove the heavy metal flocculation precipitate by backwashing to realize the recycling of the heavy metal ions; then, the hydrotalcite ceramic membrane is calcined under the condition of rich water vapor to realize the removal of the adsorbed chloride ions in the hydrotalcite ceramic membrane, and the tail gas after calcination is introduced into water to obtain a low-concentration HCl solution. Thus, the chloride ions and the heavy metals are simultaneously removed and secondarily utilized, which has high economic and environmental benefits.

[0019] (5) The material has excellent reusability, low raw material price and simple preparation method. DETAILED DESCRIPTION

[0020] The application is further described below in combination with examples, but the protection scope of the application is not limited thereto: simulate the wastewater according to the actual situation, wherein the concentration of each heavy metal ion is respectively: Fe 2+ 8.2 mg / L, Mn 2+ 56 mg / L, Ni 2+ 16 mg / L, Cd 2+ 0.18 mg / L, Zn 2+ 4 mg / L, and Cl - 168.76 mg / L.

[0021] Example 1

[0022] Step one: weigh 3 g of zirconium hydrogen phosphate and 10 g of magnesium aluminum hydrotalcite powder, mix uniformly, then completely dissolve 0.15 g of PEO in 3 mL of water, add to the mixed powder, stir uniformly, and press and form (r = 2 cm, h = 0.3 cm), then dry at 80 ℃ for 2 h. Place the sheet in a muffle furnace, calcine at 800 ℃ for 16 h, and then calcine at 200 ℃ for 2 h under the condition of water vapor concentration of 80% to obtain a porous hydrotalcite ceramic membrane.

[0023] Step two: add 0.5 g of heavy metal capture agent HMC-M1 (manufacturer: Suzhou Zhanqing Environmental Protection Technology Co., Ltd.) to 500 mL of simulated wastewater, stir for 2 h, and then pass the porous hydrotalcite ceramic membrane (11.2 g) prepared in step one to treat the wastewater, and the concentration of each heavy metal ion and chloride ion in the treated wastewater is shown in Table 1.

[0024] Example 2

[0025] Step one: weigh 4 g of zirconium hydrogen phosphate and 10 g of magnesium aluminum hydrotalcite powder, mix uniformly, then completely dissolve 0.2 g of CMC in 3 mL of water, add to the mixed powder, stir uniformly, and press and form (r = 2 cm, h = 0.3 cm), then dry at 80 ℃ for 2 h. Place the sheet in a muffle furnace, calcine at 900 ℃ for 8 h, and then calcine at 250 ℃ for 2.5 h under the condition of water vapor concentration of 60% to obtain a porous hydrotalcite ceramic membrane.

[0026] Step two: 0.5g of heavy metal capture agent HMC-M1 (manufacturer: Suzhou Zhanqing Environmental Protection Technology Co., Ltd.) was added to 500 mL of simulated wastewater, and the porous hydrotalcite ceramic membrane (11.9 g) prepared in step one was used to treat the wastewater after stirring for 2 h. The concentrations of various heavy metal ions and chloride ions in the treated wastewater are shown in Table 1.

[0027] Example 3

[0028] Step one: 3.5 g of zirconium hydrogen phosphate and 10 g of magnesium-aluminum hydrotalcite powder were mixed uniformly, and then 0.3 g of CMC was completely dissolved in 3 mL of water, added to the mixed powder, stirred uniformly, and pressed into a shape (r = 2 cm, h = 0.3 cm) and dried at 80°C for 2 h. The sheet was placed in a muffle furnace and calcined at 850°C for 10 h, and then calcined at 300°C for 3 h under a water vapor concentration of 50% to obtain a porous hydrotalcite ceramic membrane.

[0029] Step two: 0.5g of heavy metal capture agent HMC-M1 (manufacturer: Suzhou Zhanqing Environmental Protection Technology Co., Ltd.) was added to 500 mL of simulated wastewater, and the porous hydrotalcite ceramic membrane (11.6 g) prepared in step one was used to treat the wastewater after stirring for 2 h. The concentrations of various heavy metal ions and chloride ions in the treated wastewater are shown in Table 1.

[0030] Comparative Example 1

[0031] Step one: 3 g of zirconium hydrogen phosphate and 10 g of magnesium-aluminum hydrotalcite powder were mixed uniformly, and then 0.15 g of PEO was completely dissolved in 3 mL of water, added to the mixed powder, stirred uniformly, and pressed into a shape (r = 2 cm, h = 0.3 cm) and dried at 80°C for 2 h. The sheet was placed in a muffle furnace and calcined at 800°C for 16 h to obtain a porous hydrotalcite ceramic membrane.

[0032] Step two: 0.5g of heavy metal capture agent HMC-M1 (manufacturer: Suzhou Zhanqing Environmental Protection Technology Co., Ltd.) was added to 500 mL of simulated wastewater, and the porous hydrotalcite ceramic membrane (11.2 g) prepared in step one was used to treat the wastewater after stirring for 2 h. The concentrations of various heavy metal ions and chloride ions in the treated wastewater are shown in Table 1.

[0033] Comparative effect: compared with Example 1, the porous hydrotalcite ceramic membrane was not calcined under a water vapor atmosphere, the number of hydroxyl groups on the surface of the catalyst was relatively reduced, although the heavy metal ion removal efficiency was not significantly different, but the chloride ion concentration was significantly increased, i.e. the chloride ion removal efficiency was significantly reduced.

[0034] Table 1 Concentrations of various heavy metal ions in the supernatant of Examples 1-3

[0035]

Claims

1. A method for preparing a porous hydrotalcite ceramic membrane, characterized in that: The method includes the following steps: (1) Mix hydrotalcite powder with zirconium hydrogen phosphate to obtain a mixed powder, then dissolve the binder in water and mix it with the mixed powder to obtain a mixture; (2) The mixture obtained in step (1) is molded by plastic compression, dried and then calcined; then it is treated at 200-350°C for 2-4 hours under a water vapor concentration of 50-80% to form the final product.

2. The method according to claim 1, characterized in that: Hydrotalcite is one of the following: magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite, and copper aluminum hydrotalcite.

3. The method according to claim 1, characterized in that: The binder is one of polyethylene oxide or carboxymethyl cellulose.

4. The method according to claim 1, characterized in that: The mass of the binder, zirconium hydrogen phosphate and hydrotalcite powder mentioned in step (1) is (1.5-3):(30-40):

100.

5. The method according to claim 1, characterized in that: In step (2), the roasting is carried out in an air atmosphere; the roasting temperature is 800-900℃ and the roasting time is 8-16h.

6. A porous hydrotalcite ceramic membrane, characterized in that: The ceramic membrane is prepared by the method described in any one of claims 1 to 4.

7. The application of the porous hydrotalcite ceramic membrane prepared by the method of claim 1 in the removal of chloride ions and heavy metals from wastewater from heavy chemical industries.

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