Preparation method of transition metal modified biochar
By introducing transition metal modification method to biochar, the problem of difficulty in efficiently removing low-concentration multi-component VOCs in the prior art is solved, and efficient removal of organic matter such as toluene, dichloromethane and chlorobenzene is achieved, and the process is economical and environmentally friendly.
Patent Information
- Application Number
- CN202510300903.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-06-13
AI Technical Summary
The prior art is difficult to efficiently remove volatile organic compounds (VOCs), especially in industrial emissions under low concentrations and multi-component mixed states, resulting in a significant economic decline.
By a transition metal modified biochar preparation method, biochar loaded with transition metal is prepared by immersion of biomass and transition metal salt solution and hydrothermal treatment. The method includes cleaning and drying of biomass, immersion in ferrous, copper, manganese salt solutions, hydrothermal treatment and multiple recycling.
The efficient removal efficiency of volatile organic compounds such as toluene, dichloromethane and chlorobenzene was achieved, reaching 99.64%, 89.55% and 95.55%, respectively. The method is low-cost, green and environmentally friendly, and the biochar still maintains a high removal efficiency after recycling.
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Figure CN120132870A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to biochar, and in particular to a preparation method of transition metal modified biochar. Background Art
[0002] Volatile Organic Compounds (VOCs) are a class of organic compounds that are volatile under normal temperature and pressure. They are widely sourced from industrial production, vehicle exhaust, building decoration materials, and daily necessities. They can not only directly irritate the human respiratory tract and mucous membranes but also participate in atmospheric photochemical reactions, exacerbating haze and photochemical smog pollution, seriously threatening public health and the ecological environment.
[0003] For the treatment of VOCs, the technical routes are mainly divided into two categories: recovery methods and destruction methods. The recovery methods capture and enrich VOCs through physical means for resource utilization, mainly including adsorption, absorption, condensation, and membrane separation methods, etc., which are suitable for the recovery of high-concentration and single-component VOCs. The destruction methods convert VOCs into harmless substances such as CO 2 、H 2 O through chemical reactions, covering technologies such as direct combustion and catalytic oxidation. There are problems such as high operating costs and easy generation of highly toxic by-products, and they are only more effective for treating small air volumes and high-concentration VOCs. However, in actual industrial emissions, VOCs are mostly in a low-concentration and multi-component mixed state, resulting in a significant decline in the economy of existing methods.
[0004] In recent years, biochar, as a new type of environmental functional material, has become a research hotspot in the field of VOCs treatment due to its characteristics of high efficiency and low-carbon utilization. Biochar is a carbon-rich porous material produced by the thermochemical conversion process of biomass (such as straw and wood chips). Its high specific surface area, abundant surface functional groups (-COOH, -OH), and adjustable pore structure endow it with excellent adsorption ability. However, its effect on VOCs is not good, so the process needs to be further improved in practical applications to improve the effect of biochar-based materials in removing VOCs. Summary of the Invention
[0005] Object of the Invention: The object of the present invention is to provide a preparation method of transition metal modified biochar that can efficiently remove volatile organic compounds.
[0006] Technical Solution: The preparation method of the transition metal modified biochar described in the present invention includes the following steps:
[0007] (1) Clean the biomass and dry it for later use;
[0008] (2) Immerse the biomass obtained in step 1 in a transition metal salt solution and stir evenly;
[0009] (3) Hydrothermally treat the mixture obtained in step 2, and after cooling, wash and dry it;
[0010] Among them, the transition metal salt solution is a ferrous salt, a copper salt and a manganese salt solution.
[0011] Preferably, the biomass in step 1 is selected from one or more of crop straws, barks, and bamboo.
[0012] Preferably, the biomass is corn straw.
[0013] Preferably, the drying temperature in step 1 is 90 - 110 °C, and the drying time is 12 - 36 h.
[0014] Preferably, in the transition metal salt solution in step 2, the final concentration of ferrous ions is 0.1 - 0.5 mol / L, the final concentration of copper ions is 0.1 - 0.5 mol / L, and the final concentration of manganese ions is 0.1 - 0.5 mol / L.
[0015] Preferably, the transition metal salt solution in step 2 is a ferrous sulfate solution, a copper sulfate solution and a manganese chloride solution.
[0016] Preferably, the stirring and mixing time in step 2 is 6 - 12 h.
[0017] Preferably, the hydrothermal treatment temperature in step 3 is 180 - 220 °C, and the treatment time is 6 - 18 h.
[0018] Preferably, the drying temperature in step 3 is 80 - 100 °C, and the drying time is 12 - 36 h.
[0019] Preferably, deionized water is used in the washing steps in steps 1 and 3.
[0020] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: 1. Using agricultural and forestry waste biomass to prepare biochar, which has low cost and is green and environmentally friendly; 2. Preparing transition metal-loaded biochar by hydrothermal method, which is simple, convenient, low in energy consumption and high in economy, and can retain rich organic functional groups; 3. Selecting the combination of transition metals iron, copper and manganese can effectively improve the removal efficiency of volatile organic compounds of the prepared modified biochar. The removal efficiency of toluene can reach 99.64%, the removal efficiency of dichloromethane can reach 89.55%, and the removal efficiency of chlorobenzene can reach 95.55%. Brief Description of the Drawings
[0021] Figure 1 It is a comparison chart of the VOCs removal efficiency of iron, copper and manganese transition metal-modified biochar at different treatment temperatures;
[0022] Figure 2Comparison chart of the VOCs removal efficiency of iron, copper, and manganese transition metal-modified biochars with different impregnation stirring times;
[0023] Figure 3 Comparison chart of the VOCs removal efficiency of iron, copper, and manganese transition metal-modified biochars with different hydrothermal temperatures;
[0024] Figure 4 Comparison chart of the VOCs removal efficiency of iron, copper, and manganese transition metal-modified biochars with different hydrothermal times;
[0025] Figure 5 Comparison chart of the VOCs removal efficiency of iron, copper, and manganese transition metal-modified biochars with different metal ratios;
[0026] Figure 6 Efficiency chart of the cyclic use of iron, copper, and manganese transition metal-modified biochars to remove VOCs in Examples 1-4;
[0027] Figure 7 Efficiency chart of the cyclic use of iron and copper transition metal-modified biochars to remove VOCs in Comparative Examples 1-7. Detailed implementation manners
[0028] The technical solution of the present invention will be further described below.
[0029] Example 1
[0030] (1) Wash and filter the original corn straw biomass with deionized water, and dry it in an oven at 100 °C for 24 h until constant weight for standby;
[0031] (2) Add the pretreated biomass to the prepared FeSO 4 , CuSO 4 , MnCl 2 mixed solution according to the ratio of 1 g of biomass / 10 mL of transition metal solution. After impregnation and stirring, a mixture solution is obtained;
[0032] (3) Add the mixture solution to an autoclave equipped with a lining, perform hydrothermal treatment, and after natural cooling to room temperature, take the prepared substance, wash it with deionized water, filter it, and dry it in an oven at 90 °C for 24 h.
[0033] Among them, the final concentrations of FeSO 4 , CuSO 4 , MnCl 2 and the impregnation stirring time and hydrothermal treatment conditions are shown in Table 1:
[0034] Table 1 Preparation conditions of iron, copper, and manganese transition metal-modified biochars
[0035]
[0036] Performance Test:
[0037] The transition metal modified biochars prepared in Examples 1-1 to 1-15 were filled in a U-shaped tube for fixed-bed reaction, and then N 2 The standard gas flowing out of the steel cylinder was divided into two paths for use. One path was directly introduced into the volatile organic compound generating device, which included a gas collecting bottle filled with toluene or dichloromethane or chlorobenzene solution. The N 2 flowed through the volatile organic compound generating device and carried the volatile organic compound gas out; the other path was used as a balance gas and was mixed with the gas from the volatile organic compound generating device in a mixing cylinder. Among them, the total flow rate was 500 mL / min, the space velocity was 30000 h -1 , and the concentration of volatile organic compounds was 200 mg / m 3 . The flow rates of each component gas were controlled by mass flow meters. The mixed gas entered the catalyst bed of the U-shaped tube in a water bath for removal. The tail gas after being removed by the biochar loaded with transition metals was discharged from the end of the U-shaped tube and entered the VOCs detector for concentration detection.
[0038] Among them, the temperature of the water bath (i.e., the removal reaction temperature) and the removal efficiency are shown in Table 2 below:
[0039] Table 2 VOCs Removal Efficiency of Iron-Copper-Manganese Transition Metal Modified Biochar
[0040]
[0041] From the results of the above table, it can be seen that at the most suitable removal reaction temperature, i.e., 60 °C, the final concentration of 0.4 mol / L FeSO 4 , 0.4 mol / L CuSO 4 , 0.2 mol / L MnCl 2 The iron-copper-manganese transition metal modified biochar prepared by stirring and impregnating the mixed solution for 6 h and hydrothermally treating at 200 °C for 12 h had a toluene removal efficiency of 99.64%, a dichloromethane removal efficiency of 89.55%, and a chlorobenzene removal efficiency of 95.55%.
[0042] The VOCs removal efficiency of the iron-copper-manganese transition metal modified biochar at different treatment temperatures in Examples 1-1 to 1-5 is as Figure 1 shown. When the reaction temperature increased from 30 °C to 50 °C, the efficiency of the catalyst for removing VOCs also increased accordingly; when the reaction temperature was between 50 °C and 60 °C, the VOCs removal efficiency tended to be stable and reached the highest at 60 °C; when the reaction temperature further increased from 60 °C, the efficiency of the catalyst for removing VOCs gradually decreased.
[0043] The VOC removal efficiencies of the iron, copper, and manganese transition metal modified biochars in Examples 1-4, 1-10, and 1-11 with different impregnation stirring times are as follows Figure 2 shown. Impregnation stirring for 6 hours is the most preferred condition.
[0044] The VOC removal efficiencies of the iron, copper, and manganese transition metal modified biochars in Examples 1-4, 1-8, and 1-9 with different hydrothermal temperatures are as follows Figure 3 shown. When the hydrothermal temperature rises from 180 °C to 200 °C, the VOC removal efficiency of the catalyst also increases correspondingly and reaches the highest; when the hydrothermal temperature further rises from 200 °C to 220 °C, the VOC removal efficiency of the catalyst shows a downward trend.
[0045] The VOC removal efficiencies of the iron, copper, and manganese transition metal modified biochars in Examples 1-4, 1-6, and 1-7 with different hydrothermal times are as follows in the appendix Figure 4 shown. As the hydrothermal time rises from 6 h to 12 h, the VOC removal efficiency of the catalyst increases correspondingly.
[0046] The VOC removal efficiencies of the iron, copper, and manganese transition metal modified biochars in Examples 1-4, 1-12 to 1-15 with different metal ratios are as follows in the appendix Figure 5 shown. At different iron, copper, and manganese ratios, the catalyst maintains good and stable removal efficiency. When the iron, copper, and manganese ratio is 4:4:2, the catalyst reaches the best VOC removal efficiency.
[0047] The VOC removal efficiency of the iron, copper, and manganese transition metal modified biochar in Example 1-4 during cyclic use is as follows in the appendix Figure 6 shown. The used biochar is recovered, washed, filtered, and dried in an oven at 90 °C for 24 h for cyclic use. After 5 cycles, the removal efficiency of volatile organic compounds slightly decreases, but still maintains relatively good performance.
[0048] Comparative Example 1
[0049] (1) Wash and filter the original corn straw biomass with deionized water, and dry it in an oven at 100 °C for 24 h to constant weight for standby;
[0050] (2) Add the pretreated biomass to the prepared single solution of FeSO 4 , CuSO 4 , MnCl 2 or a combined solution of any two according to the ratio of 1 g biomass / 10 mL transition metal solution. After impregnation stirring, a mixture solution is obtained;
[0051] (3) Add the mixture solution into an autoclave equipped with a liner, conduct hydrothermal treatment, and after naturally cooling to room temperature, take the prepared substance, wash it with deionized water, filter it, and dry it in an oven at 90 °C for 24 h.
[0052] Among them, the final concentrations of FeSO 4 , CuSO 4 , MnCl 2 , the impregnation stirring time, and the hydrothermal treatment conditions are shown in Table 3:
[0053] Table 3 Preparation conditions of single or dual transition metal modified biochar
[0054]
[0055] Performance test:
[0056] Fill the U-shaped tube with the transition metal modified biochar prepared in the aforementioned Comparative Examples 1-1 to 1-9 for fixed bed reaction, and then divide the N 2 standard gas flowing out of the steel cylinder into two paths for use. One path is directly introduced into the volatile organic compound generating device, which includes a gas collecting cylinder filled with toluene or dichloromethane or chlorobenzene solution. The N 2 flowing out of the steel cylinder passes through the volatile organic compound generating device and carries the volatile organic compound gas out; the other path serves as a balance gas and is mixed with the gas from the volatile organic compound generating device in a mixing cylinder. Among them, the total flow rate is 500 mL / min, the space velocity is 30000 h -1 , and the concentration of volatile organic compounds is 200 mg / m 3 . The flow rates of each component gas in this process are controlled by mass flow meters. The mixed gas enters the catalyst bed layer of the U-shaped tube in a water bath for removal, and the tail gas after being removed by the biochar loaded with transition metals is discharged from the end of the U-shaped tube and enters the VOCs detector for concentration detection.
[0057] Among them, the water bath temperature (i.e., the removal reaction temperature) and the removal efficiency are shown in Table 4 below:
[0058] Table 4 VOCs removal efficiency of single or dual transition metal modified biochar
[0059]
[0060] It can be seen from the above results that the VOCs removal efficiency of single or dual transition metal modified biochar is lower than that of iron-copper-manganese transition metal modified biochar.
[0061] The VOCs removal efficiency of the iron-copper transition metal modified biochar in Comparative Example 1-7 during cyclic use is as shown in the appendix Figure 7As shown in the figure. The used biochar was recycled, washed, filtered, and dried in an oven at 90 °C for 24 h for recycling. After 5 cycles, the removal efficiency of volatile organic compounds decreased slightly, and the decrease was greater than that of iron, copper, and manganese transition metal-modified biochar.
[0062] Comparative Example 2
[0063] (1) The original corn straw biomass was washed and filtered with deionized water, and dried in an oven at 100 °C for 24 h until constant weight for standby;
[0064] (2) The pretreated biomass was added to deionized water according to the ratio of 1 g of biomass / 10 mL of deionized water, and after impregnation and stirring for 6 h, a mixture solution was obtained;
[0065] (3) The mixture solution was added to an autoclave equipped with a liner, hydrothermally treated at 200 °C for 12 h, and after natural cooling to room temperature, the prepared substance was taken, washed with deionized water, filtered, and dried in an oven at 90 °C for 24 h.
[0066] Performance test:
[0067] The biochar of Comparative Example 2 prepared above was filled in a U-shaped tube for a fixed-bed reaction, and then N 2 The standard gas flowing out of the steel cylinder was divided into two paths for use. One path was directly introduced into the volatile organic compound generating device, which included a gas collecting cylinder containing toluene or dichloromethane or chlorobenzene solution. The N 2 flowing out of the steel cylinder passed through the volatile organic compound generating device and carried the volatile organic compound gas out; the other path was used as a balance gas and mixed with the gas from the volatile organic compound generating device in a mixing cylinder. Among them, the total flow rate was 500 mL / min, the space velocity was 30,000 h -1 , and the concentration of volatile organic compounds was 200 mg / m 3 . The flow rates of each component gas in this process were controlled by mass flow meters. The mixed gas entered the catalyst bed layer of the U-shaped tube in a 60 °C water bath for removal, and the tail gas after removal by the biochar was discharged from the end of the U-shaped tube and entered the VOCs detector for concentration detection.
[0068] The toluene removal efficiency of the unmodified biochar was 33.81%, the dichloromethane removal efficiency was 27.95%, and the chlorobenzene removal efficiency was 31.20%, with poor performance.
Claims
1. A method for preparing transition metal modified biochar, characterized in that the steps include: (1) washing the biomass and drying it for later use; (2) soaking the biomass obtained in step 1 in a transition metal salt solution and stirring to mix; (3) treating the mixture obtained in step 2 by hydrothermal method, cooling it, washing it and drying it; Wherein, the transition metal salt solution is a ferrous salt, a cupric salt and a manganese salt solution.
2. The method for preparing transition metal modified biochar according to claim 1, characterized in that: The biomass in step 1 is selected from one or more of crop straw, tree bark, and bamboo.
3. The method for preparing transition metal modified biochar according to claim 2, characterized in that: The biomass is corn stalks.
4. The method for preparing transition metal modified biochar according to claim 1, characterized in that: The drying temperature in step 1 is 90-110° C., and the drying time is 12-36 hours.
5. The method for preparing transition metal modified biochar according to claim 1, characterized in that: In step 2, the final concentration of ferrous ions in the transition metal salt solution is 0.1-0.5 mol / L, the final concentration of copper ions is 0.1-0.5 mol / L, and the final concentration of manganese ions is 0.1-0.5 mol / L.
6. The method for preparing transition metal modified biochar according to claim 5, characterized in that: The transition metal salt solution in step 2 is ferrous sulfate solution, cupric sulfate solution and manganese chloride solution.
7. The method for preparing transition metal modified biochar according to claim 1, characterized in that: The stirring and mixing time in step 2 is 6-12 hours.
8. The method for preparing transition metal modified biochar according to claim 1, characterized in that: The hydrothermal treatment temperature in step 3 is 180-220° C., and the treatment time is 6-18 hours.
9. The method for preparing transition metal modified biochar according to claim 1, characterized in that: The drying temperature in step 3 is 80-100° C., and the drying time is 12-36 hours.
10. The method for preparing transition metal modified biochar according to claim 1, characterized in that: Deionized water is used in the cleaning steps described in steps 1 and 3.