Method for preparing demercuration adsorbent from bromine-based flame-retardant waste plastic and demercuration adsorbent

Abstract

This invention belongs to the technical field of solid waste resource utilization. It discloses a method for preparing a mercury removal adsorbent from brominated flame-retardant waste plastics and the mercury removal adsorbent itself. The method includes: pulverizing and drying the brominated flame-retardant waste plastics to obtain reaction raw materials; placing the reaction raw materials in a pyrolysis reactor and pyrolyzing them under an inert atmosphere to obtain solid residue; placing the solid residue in a low-temperature plasma reactor and modifying it through discharge between two electrodes; and pulverizing and grinding the modified solid residue to obtain the mercury removal adsorbent. This invention uses brominated flame-retardant waste plastics as raw materials and prepares a mercury removal adsorbent through low-temperature plasma modification. The raw material is electronic waste, which is generated in large quantities, has low cost, and is simple to prepare and modify. It can solve two problems: mercury removal from flue gas in coal-fired power plants and resource recycling of electronic waste. The use of pyrolysis reaction and low-temperature plasma modification significantly improves the mercury removal efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of solid waste resource utilization, and more specifically, relates to a method for preparing a mercury removal adsorbent from bromine-based flame-retardant waste plastics and the mercury removal adsorbent itself. Background Technology

[0002] With the continuous growth of the global population and economy, urbanization, the development of the electronics industry, and the improvement of living standards, people's demand for electronic products is increasing, and the pace of product updates is accelerating, resulting in a surge in e-waste. Brominated flame-retardant waste plastics constitute a major portion of e-waste, accounting for 30% of the total. Due to the need for flame retardancy, brominated flame-retardant waste plastics contain large amounts of brominated flame retardants, with bromine content reaching 20 wt.%. Direct incineration of these plastics would release large amounts of toxic substances such as hydrogen bromide and brominated dioxins, causing serious environmental problems. Therefore, the resource-based recycling of brominated flame-retardant waste plastics has excellent prospects and significant importance.

[0003] On the other hand, mercury pollution has become a global environmental problem, and its prevention and control have received widespread attention both domestically and internationally. Coal-fired power plants are the primary source of mercury emissions. In the flue gas of coal-fired power plants, mercury exists mainly in three forms: elemental mercury (Hg) 0 ), oxidized mercury (Hg) 2+ ), particulate mercury (Hg) p Oxidized mercury (Hg) 2+ ) and particulate mercury (Hg p Mercury can be efficiently removed using wet flue gas desulfurization (WFGD) equipment and electrostatic precipitators (ESP) or bag filters (FF). However, elemental mercury (Hg) can be... 0 Mercury is highly volatile and almost insoluble in water, making it difficult to remove through flue gas aftertreatment devices. The removal of elemental mercury has become a key and challenging issue in mercury emission control technology.

[0004] The existing flue gas activated carbon injection (ACI) method is currently the most mature and feasible technology for reducing mercury emissions in coal-fired power plants, which uses activated carbon as an adsorbent to remove mercury. However, the existing mercury removal adsorbents consume a large amount of activated carbon (carbon / mercury ratio of 2000-15000), are difficult to regenerate, and have high raw material costs. Summary of the Invention

[0005] To address the above-mentioned deficiencies or improvement needs of existing technologies, this invention provides a method for preparing mercury removal adsorbents from bromine-based flame-retardant waste plastics and the mercury removal adsorbent itself. This method solves the problems of high difficulty in regenerating activated carbon and high raw material costs in existing mercury removal adsorbents, and enables the preparation of mercury removal adsorbents using electronic waste as raw material. Furthermore, the preparation and modification of this method are simple.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a mercury removal adsorbent from bromine-based flame-retardant waste plastics is provided, comprising:

[0007] S1, bromine-based flame-retardant waste plastic is crushed and dried to obtain the reaction raw material;

[0008] S2, the reaction raw materials are placed in a pyrolysis reactor and pyrolysis is carried out under an inert atmosphere to obtain solid residue after the reaction;

[0009] S3, The solid residue is placed in a low-temperature plasma reactor, and the solid residue is modified by discharging between the two electrodes of the low-temperature plasma reactor;

[0010] S4, the modified solid residue is crushed and ground to obtain a mercury removal adsorbent.

[0011] According to the method for preparing mercury removal adsorbent from brominated flame-retardant waste plastics provided by the present invention, the brominated flame-retardant waste plastics are brominated epoxy resin waste plastics, brominated flame-retardant ABS plastics, brominated flame-retardant HIPS plastics, or mixtures thereof.

[0012] According to the method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics provided by the present invention, the particle size of the powder after crushing the bromine-based flame-retardant waste plastics in S1 is 100μm-150μm.

[0013] According to the method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics provided by the present invention, the reaction conditions for the pyrolysis reaction in S2 are: heating rate of 10℃ / min to 500-700℃, reaction pressure of atmospheric pressure, and holding time of 1h.

[0014] According to the method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics provided by the present invention, the inert atmosphere in S2 is nitrogen, and the carrier gas flow rate is 0.2L / min-0.5L / min.

[0015] According to the method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics provided by the present invention, the low-temperature plasma reactor in S3 is a space-type dielectric barrier discharge reactor with an AC frequency of 6.5-8.0 kHz, a peak voltage of 8.0-12.0 kV, and a modification time of 30-60 min.

[0016] According to the method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics provided by the present invention, the particle size of the mercury removal adsorbent in step S4 is 50 μm-75 μm.

[0017] The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics according to the present invention further includes:

[0018] S5, The mercury removal adsorbent is placed in the mercury removal performance test system to verify the mercury removal performance of the mercury removal adsorbent;

[0019] The mercury removal performance testing system includes an inert gas storage tank, a flow meter, a mercury generator, a mercury removal reactor, a temperature controller, a mixing cylinder, and a mercury analyzer. The inert gas storage tank is connected to a first branch and a second branch, respectively. The flow meter is installed on the first branch and the second branch. The mercury generator is installed on the first branch. The first branch and the second branch are respectively connected to the mixing cylinder. The mixing cylinder is connected to the mercury removal reactor and the mercury analyzer. The mercury removal reactor is connected to the mercury analyzer. Valves are installed on the first branch, the second branch, the branch where the mercury removal reactor is located, and between the mixing cylinder and the mercury analyzer. The mercury generator and the mercury removal reactor are respectively connected to the temperature controller.

[0020] The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics according to the present invention, S5 specifically includes:

[0021] The mercury removal adsorbent is placed in the mercury removal reactor, and different concentrations of elemental mercury are prepared by the mercury generator to conduct multiple mercury removal performance tests with different concentrations of elemental mercury.

[0022] For each group of mercury removal performance tests, the mercury removal efficiency was obtained based on the initial mercury concentration and the mercury concentration after adsorption.

[0023] The mercury removal performance of the adsorbent is analyzed and judged based on the mercury removal efficiency obtained from multiple sets of mercury removal performance tests.

[0024] According to another aspect of the present invention, a mercury removal adsorbent is provided, which is prepared using the method for preparing a mercury removal adsorbent from bromine-based flame-retardant waste plastics as described in any of the above claims.

[0025] In summary, compared with the prior art, the method for preparing mercury removal adsorbents from bromine-based flame-retardant waste plastics and the mercury removal adsorbent provided by this invention are as follows:

[0026] 1. A novel mercury removal adsorbent is prepared by using bromine-based flame-retardant waste plastics as raw materials and modifying them with low-temperature plasma. The raw material is electronic waste, which is generated in large quantities, has low cost, and is simple to prepare and modify. It can simultaneously solve the two problems of mercury removal from flue gas of coal-fired power plants and resource recycling of electronic waste.

[0027] 2. A novel mercury removal adsorbent is prepared by pyrolysis of bromine-based flame-retardant waste plastics. During the pyrolysis process, HBr is released, which can form C-Br functional groups with the surface groups of pyrolyzed carbon. The presence of a large number of C-Br functional groups greatly improves the adsorption and removal capacity of the mercury removal adsorbent for elemental mercury.

[0028] 3. The novel mercury removal adsorbent was further prepared by low-temperature plasma modification. After modification, the number of active functional groups such as carbonyl and ester groups on the coke increased significantly, which significantly improved the mercury removal efficiency.

[0029] 4. Furthermore, the preparation of the novel mercury removal adsorbent does not require the use of chemical reagents for modification. The low-temperature plasma uses cleaner and more efficient electricity, which reduces the difficulty of operation and the damage to the adsorbent structure. In addition, bromine has a higher polarizability than common chlorine, and its oxidation and adsorption capacity of elemental mercury is stronger. Attached Figure Description

[0030] Figure 1 This is a simplified process diagram of the preparation of mercury removal adsorbent from bromine-based flame-retardant waste plastics provided by the present invention;

[0031] Figure 2 This is a schematic diagram of the fixed-bed reaction apparatus for the pyrolysis reaction raw materials in step S2 of the present invention;

[0032] Figure 3 This is a schematic diagram of the low-temperature plasma modification reaction device provided by the present invention;

[0033] Figure 4 This is a schematic diagram of a system for testing the mercury removal performance of the mercury removal adsorbent prepared according to the present invention.

[0034] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0035] 1: High-purity inert gas cylinder; 2: Reaction raw materials; 3: Mass flow meter; 4: Quartz reaction tube; 5: Resistance heating furnace; 6: Temperature controller; 7: Ice-salt bath condenser; 8: Flow meter; 9: Low-temperature plasma reactor; 10: Solid residue; 11: Low-temperature plasma power supply; 12: Digital oscilloscope; 13: High-purity nitrogen cylinder; 14: Mass flow meter; 15: Mercury generator; 16: Temperature controller; 17: Gas mixing cylinder; 18: Mercury removal reactor; 19: Mercury analyzer. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0037] Please see Figure 1 This invention provides a method for preparing a mercury removal adsorbent from bromine-based flame-retardant waste plastics, the method comprising:

[0038] S1, bromine-based flame-retardant waste plastic is crushed and dried to obtain the reaction raw material;

[0039] S2, the reaction raw materials are placed in a pyrolysis reactor and pyrolysis is carried out under an inert atmosphere to obtain solid residue after the reaction;

[0040] S3, The solid residue is placed in a low-temperature plasma reactor, and the solid residue is modified by discharging between the two electrodes of the low-temperature plasma reactor;

[0041] S4, the modified solid residue is crushed and ground to obtain a mercury removal adsorbent.

[0042] This invention addresses the shortcomings of existing methods that use activated carbon as a mercury removal adsorbent, such as high technical costs and difficult regeneration. It provides a method for preparing a novel mercury removal adsorbent through low-temperature plasma modification of brominated flame-retardant waste plastics. This method involves pyrolyzing brominated flame-retardant waste plastics and then modifying the solid residue in a low-temperature plasma reactor to obtain the novel mercury removal adsorbent. This novel mercury removal adsorbent is suitable for the removal of elemental mercury from flue gas in coal-fired power plants.

[0043] Specifically, the method for preparing the mercury removal adsorbent involves the following steps: Step 1: First, select brominated flame-retardant waste plastic as raw material. Then, remove impurities from the raw material, i.e., remove impurities other than the brominated flame-retardant waste plastic. Next, crush and deform the brominated flame-retardant waste plastic to reduce particle size, facilitating subsequent reactions to prepare the mercury removal adsorbent. After crushing, it can be dried to obtain reaction raw materials suitable for subsequent operations. Step 2: Perform a pyrolysis reaction on the obtained reaction raw material under an inert atmosphere to obtain a solid residue after pyrolysis. Step 3: Perform low-temperature plasma modification treatment on the pyrolysis solid residue to further improve its adsorption performance. Step 4: Crush and grind the modified solid residue to obtain a mercury removal adsorbent with an appropriate particle size.

[0044] This invention provides a method for preparing a mercury removal adsorbent from brominated flame-retardant waste plastics. The method uses brominated flame-retardant waste plastics as raw materials and modifies them using low-temperature plasma to prepare a novel mercury removal adsorbent. The raw material is electronic waste, which is produced in large quantities, has low cost, and is simple to prepare and modify. It can simultaneously solve two problems: mercury removal from flue gas in coal-fired power plants and resource recycling of electronic waste. The novel mercury removal adsorbent is prepared by pyrolysis of brominated flame-retardant waste plastics. During pyrolysis, HBr is released, which can form C-Br functional groups with the surface groups of pyrolyzed carbon. The presence of a large number of C-Br functional groups greatly improves the adsorbent's ability to adsorb and remove elemental mercury. Further, the novel mercury removal adsorbent is modified using low-temperature plasma. After modification, the number of active functional groups such as carbonyl and ester groups on the coke increases significantly, resulting in a significant improvement in mercury removal efficiency. Moreover, the preparation of the novel mercury removal adsorbent does not involve chemical modification; the low-temperature plasma uses cleaner and more efficient electricity, reducing operational difficulties and damage to the adsorbent structure. In addition, bromine has a higher polarizability than common chlorine, resulting in a stronger oxidative adsorption capacity for elemental mercury.

[0045] Furthermore, the brominated flame-retardant waste plastic is brominated epoxy resin waste plastic, brominated flame-retardant ABS plastic, brominated flame-retardant HIPS plastic, or a mixture thereof.

[0046] Furthermore, the particle size of the powder after crushing the bromine-based flame-retardant waste plastic described in S1 is 100μm-150μm.

[0047] Furthermore, the pyrolysis reaction conditions described in S2 are as follows: heating rate of 10℃ / min to 500-700℃, reaction pressure of atmospheric pressure, and holding time of 1h.

[0048] Furthermore, the inert atmosphere in S2 is nitrogen, and the carrier gas flow rate is 0.2 L / min-0.5 L / min.

[0049] Furthermore, the low-temperature plasma reactor described in S3 is a space-type dielectric barrier discharge reactor with an AC frequency of 6.5-8.0kHz, a peak voltage of 8.0-12.0kV, and a modification time of 30-60min.

[0050] This invention effectively improves the mercury removal efficiency of a novel mercury removal adsorbent by optimizing the pyrolysis temperature, holding time, frequency, voltage, and residence time of the low-temperature plasma power supply in the reaction conditions. Furthermore, by setting the heating temperature to 500-700℃ and the holding time to 1 hour, the low-temperature plasma AC power frequency to 6.5-8.0 kHz, the peak voltage to 8.0-12.0 kV, and the modification time to 30-60 min, this invention ensures that the prepared novel mercury removal adsorbent achieves a mercury removal efficiency of over 50%, with the highest efficiency reaching over 95%.

[0051] Furthermore, the particle size of the mercury removal adsorbent described in S4 is 50μm-75μm.

[0052] Furthermore, methods for preparing mercury removal adsorbents from bromine-based flame-retardant waste plastics also include:

[0053] S5, the mercury removal adsorbent is placed in a mercury removal performance testing system to verify its mercury removal performance; this ensures the adsorption performance of the prepared mercury removal adsorbent. The product with superior mercury removal performance can be selected as the mercury removal adsorbent for practical applications through this performance test, providing theoretical guidance for the selection of actual mercury removal adsorbents.

[0054] refer to Figure 4 The mercury removal performance testing system includes an inert gas storage tank (which may be a high-purity nitrogen cylinder 13), a flow meter (which may be a mass flow meter 14), a mercury generator 15, a mercury removal reactor 18, a temperature controller 16, a mixing cylinder 17, and a mercury analyzer 19. The inert gas storage tank is connected to a first branch and a second branch, respectively. The first branch and the second branch are each equipped with the flow meter. The first branch is equipped with the mercury generator 15. The first branch and the second branch are respectively connected to the mixing cylinder 17. The mixing cylinder 17 is connected to the mercury removal reactor 18 and the mercury analyzer 19, respectively. The mercury removal reactor 18 is connected to the mercury analyzer 19. Valves are provided on the first branch, the second branch, the branch where the mercury removal reactor 18 is located, and between the mixing cylinder 17 and the mercury analyzer 19. The mercury generator 15 and the mercury removal reactor 18 are respectively connected to the temperature controller 16.

[0055] Furthermore, S5 specifically includes:

[0056] The mercury removal adsorbent is placed in the mercury removal reactor, and different concentrations of elemental mercury are prepared by the mercury generator to conduct multiple mercury removal performance tests with different concentrations of elemental mercury.

[0057] For each group of mercury removal performance tests, the mercury removal efficiency was obtained based on the initial mercury concentration and the mercury concentration after adsorption.

[0058] The mercury removal performance of the mercury removal adsorbent is analyzed and judged based on the mercury removal efficiency obtained from multiple sets of mercury removal performance tests. For example, for a prepared mercury removal adsorbent, the average value of multiple mercury removal efficiencies obtained from multiple sets of mercury removal performance tests can be taken as the final mercury removal efficiency of the mercury removal adsorbent; alternatively, the highest value can be selected, and there is no specific limitation.

[0059] Furthermore, the present invention also provides a mercury removal adsorbent, which is prepared using the method for preparing a mercury removal adsorbent from bromine-based flame-retardant waste plastics as described in any of the above embodiments.

[0060] Furthermore, this invention belongs to the field of solid waste resource utilization and adsorbent preparation, and discloses a method and product for preparing a mercury removal adsorbent by modifying brominated flame-retardant waste plastics through low-temperature plasma. The specific steps of this method are as follows: the brominated flame-retardant waste plastics are crushed and placed in a pyrolysis reactor to obtain pyrolytic carbon under an inert atmosphere; the pyrolytic carbon is then placed in a plasma reaction device and modified using surface dielectric barrier discharge low-temperature plasma technology to prepare a novel mercury removal adsorbent. The raw material of this invention is electronic waste, which is generated in large quantities, has low cost, and the preparation method is simple. It can simultaneously solve the problems of mercury removal from flue gas of coal-fired power plants and the resource utilization and recycling of electronic waste. Because the low-temperature plasma generates a large number of highly reactive substances such as high-energy electrons, ions, and free radicals, these substances readily react with other atoms, molecules, or free radicals, thereby greatly improving the chemical adsorption capacity of the adsorbent for elemental mercury.

[0061] The present invention will be further explained by taking the preparation of a novel mercury removal adsorbent by low-temperature plasma modification of bromine-based flame-retardant waste plastics as an example.

[0062] Specific Example 1

[0063] Step (a): Select waste FR4-1 brominated epoxy resin, screen to remove impurities, pulverize into 100μm powder, dry in a drying oven at 45℃ for 24h, cool to room temperature and take out to obtain brominated flame retardant waste plastic powder, i.e. reaction raw material 2.

[0064] Step (b): Place the brominated flame-retardant waste plastic powder obtained in step (a) into... Figure 2 The fixed-bed pyrolysis apparatus shown uses a mass flow meter 3 to control the release of high-purity inert gas from the high-purity inert gas cylinder 1. The inert gas is high-purity nitrogen at a flow rate of 200 mL / min. After the high-purity nitrogen is introduced for 10 min to change the atmosphere inside the quartz reaction tube 4 to inert, the resistance heating furnace 5 is heated from room temperature to 500°C at a heating rate of 10°C / min using a temperature controller 6 and held at that temperature for 1 h. After the reaction is completed, the mixture is cooled to room temperature to obtain the solid residue 10 after the reaction. The ice-salt bath condensation device 7 is used to condense the tar produced after the reaction, which can be recycled and reused, reducing environmental pollution.

[0065] Step (c): Place the solid residue 10 prepared in step (b) into... Figure 3The low-temperature plasma reactor 9 of the low-temperature plasma reaction device shown is controlled by the air flow meter 8. The electrodes of the low-temperature plasma reactor 9 are energized by the low-temperature plasma power supply 11. The peak voltage and frequency are displayed on the digital oscilloscope 12. The AC frequency is controlled to be 6.5kHz, the peak voltage is 8.0kV, and the modification time is 30min by the low-temperature plasma power supply 11. The discharge power is calculated by the area of ​​the Lissajous figure on the digital oscilloscope 12.

[0066] Step (d): Grind the modified solid residue from step (c) into powder with a particle size of 50 μm to obtain the desired mercury removal adsorbent.

[0067] Take 200mg of the novel mercury removal adsorbent and place it in Figure 4 In the mercury removal reactor 18, the flow rate of high-purity nitrogen carrier gas released from the high-purity nitrogen cylinder 13 is set to 500 mL / min. Mercury vapor generated in the mercury generator 15 is introduced into the mercury removal reactor 18. The adsorption temperature in the mercury removal reactor 18 is controlled at 140℃ by the temperature controller 16 to obtain different Hg values. 0 The mercury removal efficiency at different concentrations is shown in Table 1. The flow rate of nitrogen gas entering the branch where the mercury generator 15 is located can be controlled by the mass flow meter 14, and the temperature in the mercury generator 15 can be controlled by the temperature controller 16, thereby enabling the mercury generator 15 to generate Hg of different concentrations. 0 Setting up mixing cylinder 17 to mix the gas flow from the first and second branches is beneficial for increasing the Hg content. 0 To ensure airflow stability, first close the valve on the branch where the mercury removal reactor 18 is located, then open the valve between the mixing cylinder 17 and the mercury analyzer 19 to detect and obtain Hg. 0 Initial concentration. By closing the valve between the gas mixing cylinder 17 and the mercury analyzer 19, and opening the valve on the branch where the mercury removal reactor 18 is located, the Hg after adsorption by the mercury removal adsorbent can be detected and obtained. 0 The concentration can then be used to calculate the mercury removal efficiency.

[0068] Table 1 shows the test results of mercury removal efficiency of the mercury removal adsorbent in Specific Example 1.

[0069]

[0070] Specific Example 2

[0071] Step (a): Select waste bromine-based flame-retardant ABS plastic, screen out impurities, pulverize into 100μm powder, dry in a drying oven at 45℃ for 24h, cool to room temperature and take out to obtain bromine-based flame-retardant waste plastic powder, i.e., reaction raw material 2.

[0072] Step (b): Place the brominated flame-retardant waste plastic powder obtained in step (a) into... Figure 2The fixed-bed pyrolysis apparatus shown uses a mass flow meter 3 to control the release of high-purity inert gas from the high-purity inert gas cylinder 1. The inert gas is high-purity nitrogen at a flow rate of 200 mL / min. After the high-purity nitrogen is introduced for 10 min to change the atmosphere inside the quartz reaction tube 4 to inert, the resistance heating furnace 5 is heated from room temperature to 600°C at a heating rate of 10°C / min using a temperature controller 6 and held at that temperature for 1 h. After the reaction is completed, the mixture is cooled to room temperature to obtain the solid residue 10 after the reaction. The ice-salt bath condensation device 7 is used to condense the tar produced after the reaction, which can be recycled and reused, reducing environmental pollution.

[0073] Step (c): Place the solid residue 10 prepared in step (b) into... Figure 3 The low-temperature plasma reactor 9 of the low-temperature plasma reaction device shown is controlled by a flow meter 8. The electrodes of the low-temperature plasma reactor 9 are energized by a low-temperature plasma power supply 11. The peak voltage and frequency are displayed on a digital oscilloscope 12. The AC frequency is controlled to be 7.5kHz, the peak voltage is 10.0kV, and the modification time is 45min by the low-temperature plasma power supply 11. The discharge power is calculated by the area of ​​the Lissajous figure on the digital oscilloscope 12.

[0074] Step (d): Grind the modified solid residue from step (c) into powder with a particle size of 50 μm to obtain the desired mercury removal adsorbent.

[0075] Take 200mg of the novel mercury removal adsorbent and place it in Figure 4 In the mercury removal reactor 18, the flow rate of high-purity nitrogen carrier gas released from the high-purity nitrogen cylinder 13 is set to 500 mL / min. Mercury vapor generated in the mercury generator 15 is introduced into the mercury removal reactor 18. The adsorption temperature in the mercury removal reactor 18 is controlled at 140℃ by the temperature controller 16 to obtain different Hg values. 0 The mercury removal efficiency at different concentrations is shown in Table 2.

[0076] Table 2 shows the test results of mercury removal efficiency of the mercury removal adsorbent in specific example 2.

[0077]

[0078] Specific Example 3

[0079] Step (a): Select waste brominated flame-retardant HIPS plastic, screen out impurities and crush it into 100μm powder, dry it in a drying oven at 45℃ for 24h, cool it to room temperature and take it out to obtain brominated flame-retardant waste plastic powder, which is reaction raw material 2.

[0080] Step (b): Place the brominated flame-retardant waste plastic powder obtained in step (a) into... Figure 2The fixed-bed pyrolysis apparatus shown uses a mass flow meter 3 to control the release of high-purity inert gas from the high-purity inert gas cylinder 1. The inert gas is high-purity nitrogen at a flow rate of 200 mL / min. After the high-purity nitrogen is introduced for 10 min to change the atmosphere inside the quartz reaction tube 4 to inert, the resistance heating furnace 5 is heated from room temperature to 700°C at a heating rate of 10°C / min using a temperature controller 6 and held at that temperature for 1 h. After the reaction is completed, the mixture is cooled to room temperature to obtain the solid residue 10 after the reaction. The ice-salt bath condensation device 7 is used to condense the tar produced after the reaction, which can be recycled and reused, reducing environmental pollution.

[0081] Step (c): Place the solid residue 10 prepared in step (b) into... Figure 3 The low-temperature plasma reactor 9 of the low-temperature plasma reaction device shown is controlled by a flow meter 8. The electrodes of the low-temperature plasma reactor 9 are energized by a low-temperature plasma power supply 11. The peak voltage and frequency are displayed on a digital oscilloscope 12. The AC frequency is controlled to be 8.0 kHz, the peak voltage is 12.0 kV, and the modification time is 60 min by the low-temperature plasma power supply 11. The discharge power is calculated by the area of ​​the Lissajous figure on the digital oscilloscope 12.

[0082] Step (d): Grind the modified solid residue from step (c) into powder with a particle size of 50 μm to obtain the desired mercury removal adsorbent.

[0083] Take 200mg of the novel mercury removal adsorbent and place it in Figure 4 In the mercury removal reactor 18, the flow rate of high-purity nitrogen carrier gas released from the high-purity nitrogen cylinder 13 is set to 500 mL / min. Mercury vapor generated in the mercury generator 15 is introduced into the mercury removal reactor 18. The adsorption temperature in the mercury removal reactor 18 is controlled at 140℃ by the temperature controller 16 to obtain different Hg values. 0 The mercury removal efficiency at different concentrations is shown in Table 3.

[0084] Table 3 shows the test results of mercury removal efficiency of the mercury removal adsorbent in specific example 3.

[0085]

[0086] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics, characterized in that, include: S1, bromine-based flame-retardant waste plastic is crushed and dried to obtain the reaction raw material; S2, the reaction raw materials are placed in a pyrolysis reactor and pyrolysis is carried out under an inert atmosphere to obtain solid residue after the reaction; S3, The solid residue is placed in a low-temperature plasma reactor, and the solid residue is modified by discharging between the two electrodes of the low-temperature plasma reactor; S4, the modified solid residue is crushed and ground to obtain a mercury removal adsorbent; The low-temperature plasma reactor described in S3 is a space-type dielectric barrier discharge reactor with an AC frequency of 6.5-8.0kHz, a peak voltage of 8.0-12.0kV, and a modification time of 30-60min.

2. The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics as described in claim 1, characterized in that, The brominated flame-retardant waste plastics are brominated epoxy resin waste plastics, brominated flame-retardant ABS plastics, brominated flame-retardant HIPS plastics, or mixtures thereof.

3. The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics as described in claim 1, characterized in that, The particle size of the powder after crushing the bromine-based flame-retardant waste plastic described in S1 is 100μm-150μm.

4. The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics as described in claim 1, characterized in that, The pyrolysis reaction conditions described in S2 are as follows: heating rate of 10℃ / min to 500-700℃, reaction pressure of atmospheric pressure, and holding time of 1h.

5. The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics as described in claim 1, characterized in that, In S2, the inert atmosphere is nitrogen, and the carrier gas flow rate is 0.2 L / min - 0.5 L / min.

6. The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics as described in claim 1, characterized in that, The particle size of the mercury removal adsorbent described in S4 is 50μm-75μm.

7. The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics according to any one of claims 1-6, characterized in that, Also includes: S5, The mercury removal adsorbent is placed in the mercury removal performance test system to verify the mercury removal performance of the mercury removal adsorbent; The mercury removal performance testing system includes an inert gas storage tank, a flow meter, a mercury generator, a mercury removal reactor, a temperature controller, a mixing cylinder, and a mercury analyzer. The inert gas storage tank is connected to a first branch and a second branch, respectively. The flow meter is installed on the first branch and the second branch. The mercury generator is installed on the first branch. The first branch and the second branch are respectively connected to the mixing cylinder. The mixing cylinder is connected to the mercury removal reactor and the mercury analyzer. The mercury removal reactor is connected to the mercury analyzer. Valves are installed on the first branch, the second branch, the branch where the mercury removal reactor is located, and between the mixing cylinder and the mercury analyzer. The mercury generator and the mercury removal reactor are respectively connected to the temperature controller.

8. The method for preparing mercury removal adsorbent from bromine-based flame-retardant waste plastics as described in claim 7, characterized in that, S5 specifically includes: The mercury removal adsorbent is placed in the mercury removal reactor, and different concentrations of elemental mercury are prepared by the mercury generator to conduct multiple mercury removal performance tests with different concentrations of elemental mercury. For each group of mercury removal performance tests, the mercury removal efficiency was obtained based on the initial mercury concentration and the mercury concentration after adsorption. The mercury removal performance of the adsorbent is analyzed and judged based on the mercury removal efficiency obtained from multiple sets of mercury removal performance tests.

9. A mercury removal adsorbent, characterized in that, The method for preparing mercury removal adsorbent using any one of the bromine-based flame-retardant waste plastics according to claims 1-8.

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