A preparation method of filter membrane electrode for efficiently removing heavy metals from solution

Abstract

The invention discloses a method for preparing a filter membrane electrode for efficiently removing heavy metals in a solution. A novel filter electrode is prepared by using waste biomass. The filter membrane electrode can realize efficient removal and recovery of water samples containing heavy metals Cu, Cd and Pb in a short time. For a cadmium-containing solution with a concentration of 100ppm and a copper-containing solution with a concentration of 10000ppm, a removal efficiency of more than 96% can be achieved within 30 minutes. For a lead-containing solution with a concentration of 1000ppm, a heavy metal removal efficiency of 91.8% can also be achieved after treatment for 5 hours. The heavy metal removal and recovery process of the invention is simple, the heavy metal recovery cost is low, and the industrialization potential is strong.

Description

Technical Field

[0001] The invention relates to a method for making and applying a filter membrane electrode capable of efficiently removing and recovering heavy metals in a leaching process, and belongs to the technical field of materials and electrochemistry. Background Art

[0002] Heavy metal pollution is a common type of soil pollution. Filter electrodes are a new type of soil remediation technology that effectively removes heavy metals from soil and solution. The filter electrode method is a method of removing heavy metal ions through electrochemical reactions. It is an efficient, low-cost, and environmentally friendly soil remediation technology. The principle of the filter electrode method is to use electrochemical reactions to reduce heavy metal ions into metal precipitates, thereby achieving the purpose of removing heavy metal ions. However, the wastewater treated by the leaching technology needs to be treated, which has a high treatment cost and is prone to secondary pollution. Therefore, a better technology needs to be developed to treat the leaching wastewater. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a method for efficiently removing heavy metals from a solution and effectively recovering the removed heavy metals, namely, a method for preparing a leaching and filtering membrane electrode and a method for efficiently removing heavy metals from a solution and recovering the heavy metals.

[0004] The technical solution of the present invention is as follows:

[0005] A method for preparing a filter membrane electrode for efficiently removing heavy metals from a solution, the specific steps are as follows:

[0006] (1) Put the waste biomass into a crucible, compact it, wrap the crucible with tin foil, cover it, and place the crucible in a box-type muffle furnace;

[0007] (2) starting the heating mode, raising the temperature to a first predetermined temperature at a heating rate of 5-10°C / min, and maintaining the first predetermined temperature at a constant temperature for 1-2 hours, so that the biomass in the tinfoil is evenly heated; continuing to start the heating mode, raising the first predetermined temperature to a second predetermined temperature, and maintaining the second predetermined temperature at a constant temperature for 0.5-4 hours, so that the biomass in the tinfoil is fully carbonized into biochar;

[0008] (3) the temperature of the muffle furnace is reduced to below 200° C., the biochar wrapped in tin foil is taken out and cooled to room temperature in a dry environment to obtain the biochar;

[0009] (4) In a 25 mL beaker, add 1-2 mL of polytetrafluoroethylene emulsion and 2-4 mL of anhydrous ethanol, and mix them by magnetic stirring at a speed of 800 r / min for 15-20 min;

[0010] (5) When the liquid is viscous, add 1.5-2 g of the biochar obtained in step (3) to the mixed liquid of step (4), stir and mix, and after the mixture becomes viscous due to polymerization, take it out and place it on a clean plastic plate and knead it repeatedly. When the slurry becomes gelatinous, roll it and place the roller material on a stainless steel net. Use a homogeneous stainless steel cylinder to press the electrode. After pressing, place it in a 110°C oven for 24 hours to prepare a membrane electrode.

[0011] In step (2), the first predetermined temperature is 350-450°C; the second predetermined temperature is 550-650°C.

[0012] The mass fraction of the polytetrafluoroethylene emulsion in step (4) is 10%.

[0013] The present invention also provides an application method of the filter membrane electrode for efficiently removing heavy metals in a solution, and the specific steps are as follows:

[0014] A. Cut the membrane electrode according to the size of the elution device to obtain two electrodes, install them at the bottom of the elution device, separate the edges of the two electrodes by waterproof insulating material, leave a gap of 0.5-1.0 cm between the two electrodes, connect the upper electrode to the positive electrode, connect the lower electrode to the negative electrode, and connect the positive and negative electrodes to direct current;

[0015] B. Add heavy metal pollutants into the elution device, start the DC output device to output 20V DC, start the constant current pump, and circulate the elution liquid filtered under the reactor into the elution device again. The flow rate of the constant current pump is 0.5ml / min. After 5h of elution reaction, a large amount of heavy metal deposits adhere to the surface of the negative electrode and are washed and recovered.

[0016] During the flushing and recovery in step B, most of the sediment can be recovered by flushing with deionized water, and the remaining small amount of heavy metals inside the filter electrode can be recovered by flushing with low-concentration nitric acid.

[0017] The advantages of the present invention are:

[0018] 1. The filtration biochar membrane electrode of the present invention is made by burning waste biomass, which has the advantages of easy acquisition of raw materials and low cost.

[0019] 2. The heavy metal removal and recovery process of the present invention is simple, the heavy metal recovery cost is low, and the industrialization potential is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a physical picture of the filter membrane electrode produced using the above process;

[0021] Figure 2 Schematic diagram of membrane electrode installation;

[0022] Figure 3The concentration and time variation diagram of 100mL of heavy metal water sample containing 10000ppm copper in the reactor treatment;

[0023] Figure 4 Heavy metals deposited in 100 mL of a water sample containing 10,000 ppm of copper after being treated in a reactor for 5 hours;

[0024] Figure 5 The concentration and time variation diagram of 100mL of heavy metal water sample containing cadmium at a concentration of 100ppm after being treated in the reactor;

[0025] Figure 6 Heavy metals deposited in 100mL of heavy metal water sample containing 100ppm cadmium after being treated in the reactor for 5h;

[0026] Figure 7 The concentration and time variation diagram of 100mL of heavy metal water sample containing 1000ppm lead in the reactor treatment;

[0027] Figure 8 Heavy metals deposited in 100mL of water sample containing 1000ppm lead after being treated in the reactor for 5h. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the described contents.

[0029] The mass fraction of the polytetrafluoroethylene emulsion used in the embodiment of the present invention is 10%, which is purchased from Shenzhen Kejing Zhida Technology Co., Ltd. The trade name is PTFE polytetrafluoroethylene concentrate, which is a milky white or slightly yellow uniform emulsion.

[0030] Example 1

[0031] A method for efficiently removing copper from a solution and effectively recovering copper, the specific steps are as follows:

[0032] A. Preparation of membrane electrode:

[0033] (1) Put the waste biomass corn stalks into a crucible, compact it, wrap the crucible with tin foil, cover it, and place the crucible in a box-type muffle furnace;

[0034] (2) Start the heating mode, raise the temperature to a first predetermined temperature of 350°C at a heating rate of 5°C / min, and maintain the first predetermined temperature at a constant temperature for 2 hours, so that the biomass in the tin foil is evenly heated; continue to start the heating mode, raise the first predetermined temperature to a second predetermined temperature of 650°C at a heating rate of 5°C / min, and maintain the second predetermined temperature at a constant temperature for 0.5 hours, so that the biomass in the tin foil is fully carbonized into biochar;

[0035] (3) The temperature of the muffle furnace drops below 200°C, and the biochar wrapped in tin foil is taken out and cooled to room temperature in a dry environment;

[0036] (4) In a 25 mL beaker, add 2 mL of polytetrafluoroethylene emulsion (mass fraction 10%) and 4 mL of anhydrous ethanol and mix them by magnetic stirring at 800 r / min for 20 min;

[0037] (5) When the liquid is viscous, add 2g of biochar and stir for 8 minutes. When the mixture becomes viscous due to polymerization, take it out and place it on a clean plastic plate and knead it repeatedly for 10 minutes. When the slurry becomes colloid, roll it and place the roller material on a stainless steel net. Use a 2Kg homogenous stainless steel cylinder to press the electrode. Press the entire colloid on the stainless steel net. After pressing, place it in a 110°C oven for 24 hours to prepare a membrane electrode. Figure 1 Shown is a physical picture of the filter membrane electrode;

[0038] B. After the filter membrane electrode is prepared, trim the filter membrane electrode according to the size of the filtration equipment to form two electrodes, such as Figure 2 As shown, it is installed at the bottom of the elution device, the upper electrode is connected to the positive electrode, the lower electrode is connected to the negative electrode, the edges of the two electrodes are separated by an insulating waterproof rubber ring, and there is a gap of 0.5-1.0cm between the two electrodes in the treatment working area;

[0039] C. Connect the positive and negative electrodes to the DC output device;

[0040] D. Prepare 100 mL of a copper solution with a concentration of 10,000 ppm using copper nitrate, add the prepared heavy metal solution into the elution device, start the waveform generator, and apply 20 V DC to the stainless steel mesh of the electrode during the elution process; start the constant current pump to circulate the filtered eluent below the reactor into the elution device again, and the flow rate of the constant current pump is 0.5 mL / min;

[0041] E. After 5 hours of elution reaction, the positive and negative electrodes are removed. A large amount of copper electrochemical deposits are attached to the surface of the negative electrode. Most of the deposits can be recovered by washing with deionized water. The remaining small amount of heavy metals inside the filter electrode can be washed with low-concentration nitric acid for recovery. Samples are taken intermittently during the reaction, and the concentration changes of heavy metals in the solution are tested by flame atomic absorption spectrometry to observe the removal efficiency.

[0042] Figure 3 The concentration variation graph of 100mL of heavy metal water sample containing 10000ppm copper in the reactor is plotted against time. From the graph, we can see that the removal rate of Cu can reach more than 96% after 30 minutes of treatment.

[0043] Figure 4The negative electrode surface image of 100mL of heavy metal water sample containing copper at a concentration of 10000ppm after being treated in the reactor for 5 hours. It can be seen from the figure that heavy metals are deposited in large quantities on the negative electrode surface, most of which are in solid form.

[0044] Example 2

[0045] A method for efficiently removing cadmium from a solution and effectively recovering cadmium, the specific steps are as follows:

[0046] A. Preparation of membrane electrode:

[0047] (1) Put the waste biomass corn stalks into a crucible, compact it, wrap the crucible with tin foil, cover it, and place the crucible in a box-type muffle furnace;

[0048] (2) starting the heating mode, raising the temperature to a first predetermined temperature of 450°C at a heating rate of 10°C / min, and maintaining the first predetermined temperature at a constant temperature for 1 hour, so that the biomass in the tinfoil is evenly heated; continuing to start the heating mode, raising the first predetermined temperature to a second predetermined temperature of 550°C at a heating rate of 10°C / min, and maintaining the second predetermined temperature at a constant temperature for 4 hours, so that the biomass in the tinfoil is fully carbonized into biochar;

[0049] (3) The temperature of the muffle furnace drops below 200°C, and the biochar wrapped in tin foil is taken out and cooled to room temperature in a dry environment;

[0050] (4) In a 25 mL beaker, add 1 mL of polytetrafluoroethylene emulsion (mass fraction 10%) and 2 mL of anhydrous ethanol and mix them by magnetic stirring at a speed of 800 r / min for 15 min;

[0051] (5) When the liquid is viscous, add 1.5 g of the biochar prepared in step (2) and stir for 8 minutes. After the mixture becomes viscous due to polymerization, take it out and place it on a clean plastic plate and knead it repeatedly for 10 minutes. When the slurry becomes colloid, roll it and place the roller material on a stainless steel mesh. Use a 2 kg homogenized stainless steel cylinder to press the electrode, press the entire colloid on the stainless steel mesh, and place it in a 110 ° C oven for 24 hours after pressing to prepare a membrane electrode;

[0052] B. After the filter membrane electrode is prepared, trim the filter membrane electrode according to the size of the filtration equipment to form two electrodes, which are installed at the bottom of the elution device. The upper electrode is connected to the positive electrode, and the lower electrode is connected to the negative electrode. The edges of the two electrodes are separated by an insulating waterproof rubber ring. There is a gap of 0.5-1.0 cm between the two electrodes in the treatment working area.

[0053] C. Connect the positive and negative electrodes to the DC output device;

[0054] D. Prepare 100 mL of cadmium-containing solution with a concentration of 100 ppm using cadmium nitrate, add the prepared heavy metal solution into the elution device, start the direct current output device, and apply 20 V direct current to the stainless steel mesh of the electrode during the elution process; start the constant current pump, and circulate the eluent filtered below the reactor into the elution device again, with a flow rate of 0.5 mL / min;

[0055] E. After 5 hours of elution reaction, the positive and negative electrodes are removed. A large amount of cadmium electrochemical deposits are attached to the surface of the negative electrode. Most of the deposits can be recovered by washing with deionized water. The remaining small amount of heavy metals inside the filter electrode can be washed with low-concentration nitric acid to achieve recovery. Sampling is also intermittently taken during the reaction process, and the concentration changes of heavy metals in the solution are tested by flame atomic absorption spectrometry to observe the removal efficiency.

[0056] Figure 5 The concentration variation graph of 100mL of heavy metal water sample containing cadmium at a concentration of 100ppm after treatment in the reactor. From the graph, it can be seen that the removal rate of Cd metal element can reach more than 96% after 30 minutes of treatment.

[0057] Figure 6 The negative electrode surface image of 100mL of heavy metal water sample containing cadmium at a concentration of 100ppm after being treated in the reactor for 5 hours. It can be seen from the figure that heavy metals are deposited in large quantities on the negative electrode surface, most of which are in solid form.

[0058] Example 3

[0059] A method for efficiently removing lead from a solution and effectively recovering lead, the specific steps are as follows:

[0060] A. Preparation of membrane electrode:

[0061] (1) Put the waste biomass wheat straw into a crucible, compact it, wrap the crucible with tin foil, cover it, and place the crucible in a box-type muffle furnace;

[0062] (2) starting the heating mode, raising the temperature to a first predetermined temperature of 400°C at a heating rate of 6°C / min, and maintaining the first predetermined temperature at a constant temperature for 1.5 hours, so that the biomass in the tinfoil is evenly heated; continuing to start the heating mode, raising the first predetermined temperature to a second predetermined temperature of 600°C at a heating rate of 6°C / min, and maintaining the second predetermined temperature at a constant temperature for 2 hours, so that the biomass in the tinfoil is fully carbonized into biochar;

[0063] (3) The temperature of the muffle furnace drops below 200°C, and the biochar wrapped in tin foil is taken out and cooled to room temperature in a dry environment;

[0064] (4) In a 25 mL beaker, add 1.5 mL of polytetrafluoroethylene emulsion (mass fraction 10%) and 3 mL of anhydrous ethanol, and mix them by magnetic stirring at a speed of 800 r / min for 16 min;

[0065] (5) When the liquid is viscous, add 1.6 g of biochar and stir for 8 minutes. When the mixture becomes viscous due to polymerization, take it out and place it on a clean plastic plate and knead it repeatedly for 10 minutes. When the slurry becomes colloid, roll it and place the roller material on a stainless steel net. Use a 2 kg homogenous stainless steel cylinder to press the electrode, press the entire colloid on the stainless steel net, and place it in a 110 ° C oven for 24 hours after pressing to prepare a membrane electrode;

[0066] B. After the filter membrane electrode is prepared, trim the filter membrane electrode according to the size of the filtration equipment to form two electrodes, which are installed at the bottom of the elution device. The upper electrode is connected to the positive electrode, and the lower electrode is connected to the negative electrode. The edges of the two electrodes are separated by an insulating waterproof rubber ring. There is a gap of 0.5-1.0 cm between the two electrodes in the treatment working area.

[0067] C. Connect the positive and negative electrodes to the DC output device;

[0068] D. Prepare 100 mL of a lead solution with a concentration of 1000 ppm using lead nitrate, add the prepared heavy metal solution into the elution device, start the waveform generator, and apply 20 V DC to the stainless steel mesh of the electrode during the elution process; start the constant current pump to circulate the filtered eluent below the reactor into the elution device again, and the flow rate of the constant current pump is 0.5 mL / min;

[0069] E. After 5 hours of elution reaction, the positive and negative electrodes are removed. A large amount of lead electrochemical deposits are attached to the surface of the negative electrode. Most of the deposits can be recovered by washing with deionized water. The remaining small amount of heavy metals inside the filter electrode can be washed with low concentration nitric acid to achieve recovery. Samples are taken intermittently during the reaction, and the concentration changes of heavy metals in the solution are tested by flame atomic absorption spectrometry to observe the removal efficiency.

[0070] Figure 7 The concentration variation graph of 100mL of heavy metal water sample containing 1000ppm lead in the reactor treatment is as follows: from the graph, it can be seen that the removal rate of Pb metal element can also reach about 91.8% after 5h of treatment.

[0071] Figure 8 The negative electrode surface image of 100mL of heavy metal water sample containing lead at a concentration of 1000ppm after being treated in the reactor for 5 hours. It can be seen from the figure that heavy metals are deposited in large quantities on the negative electrode surface, most of which are in solid form.

[0072] The above embodiment of the present invention was tested in 100 mL of solution with Cu, Pb and Cd concentrations of 10000 ppm, 1000 ppm and 100 ppm respectively, and the removal rate was high and the removal effect was good. According to the properties of activated carbon, physical adsorption is affected by factors such as adsorption sites and adsorption capacity. Therefore, there is reason to believe that the removal efficiency of conventional activated carbon for heavy metals in high-concentration contaminated heavy metal soils will be much lower than that of the present invention.

Claims

1. A method for preparing a membrane electrode for efficiently removing heavy metals from a solution, characterized in that: The specific steps are as follows: (1) Put the waste biomass into a crucible and compact it, wrap the crucible with tin foil, cover it and put the crucible into the furnace; (2) Turn on the heating mode, heat up to the first preset temperature at a heating rate of 5-10°C / min, keep the temperature constant for 1-2 hours, and continue to heat up to the second preset temperature, keep the temperature constant for 0.5-4 hours; the first preset temperature is 350-450°C; the second preset temperature is 550-650°C; (3) In step (2), the temperature is lowered to below 200°C in the furnace, and the tin foil is removed and cooled to room temperature in a dry environment to obtain biochar; (4) Mix 1-2 mL of polytetrafluoroethylene emulsion and 2-4 mL of anhydrous ethanol, and stir magnetically at a speed of 800 r / min for 15-20 min; the mass fraction of polytetrafluoroethylene emulsion is 10%; (5) Add 1.5-2 g of biochar to the mixed solution of step (4), stir and mix, and knead repeatedly until it becomes a gel, then roll it, place the roller material on a stainless steel mesh for pressing, and then place it in a 110°C oven for 24 hours to prepare a membrane electrode; The application of the membrane electrode prepared by the preparation method comprises the following specific steps: A. Cut the membrane electrode according to the size of the elution device to obtain two electrodes, install them at the bottom of the elution device, separate the edges of the two electrodes by waterproof insulating material, leave a gap of 0.5-1.0 cm between the two electrodes, connect the upper electrode to the positive electrode, connect the lower electrode to the negative electrode, and connect the positive and negative electrodes to direct current; B. Add heavy metal pollutants into the elution device, start the DC output device, start the constant current pump, and circulate the filtered elution liquid into the elution equipment again; after 5 hours of elution reaction, the heavy metal sediments adhere to the surface of the negative electrode and are rinsed and recovered.

2. The preparation method according to claim 1, characterized in that: During the flushing and recovery in step B, most of the sediment is recovered by flushing with deionized water, and the remaining small amount of heavy metals inside the electrode are flushed with low-concentration nitric acid to achieve recovery.

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