Electroadsorption Demulsification Method Based on Biomass Carbon-Based Electrode and Its Application

Abstract

This invention discloses a demulsification method based on biomass char-based material electrodes using electroadsorption and its application. This method uses integral biomass char-based material as the electrode to perform electroadsorption demulsification and oil removal treatment on oily emulsified wastewater under low voltage. This invention also discloses a method for manufacturing a biomass char-based electrode for efficiently treating oily emulsified wastewater and its application in demulsification and oil removal of various oily emulsified wastewaters. This invention combines readily available, inexpensive, naturally porous biomass char material with excellent adsorption performance with electroadsorption technology, achieving efficient demulsification while significantly adsorbing and removing organic matter from emulsified wastewater. This demulsification method has advantages such as low cost, abundant and readily available raw materials, low energy consumption, and high efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, in particular to a biomass charcoal-based material electrode electric adsorption demulsification method and application. BACKGROUND

[0002] Various industrial processes, including metal processing, pharmaceutical, food and crude oil industries, can produce a large amount of oil-containing emulsified wastewater. The components of oil-containing emulsified wastewater are often complex, mainly composed of 5%-10% base oil, a small amount of various additives, and a large amount of water, etc., with high organic content, which is difficult to be treated by biochemical method. The presence of emulsion often leads to corrosion and rust of production equipment, increasing the operation and production cost. In addition, emulsion has mutagenicity and carcinogenicity to human health, and can inhibit plant growth and harm the ecological environment.

[0003] Traditional demulsification and oil removal methods have the disadvantages of high cost, complex operation, secondary pollution, low efficiency, etc. For example, chemical demulsification requires adding demulsifying agents to wastewater, causing secondary pollution of wastewater. In physical demulsification, electric field demulsification and centrifugal demulsification require a large amount of energy consumption, and ordinary activated carbon has limited adsorption capacity. Biological demulsification requires cultivation of microorganisms, time-consuming, large equipment space occupation, long treatment cycle, and the need to treat activated sludge, etc.

[0004] Electric adsorption technology is a technology that removes pollutants in wastewater at low voltage, which can greatly improve the adsorption performance of carbon materials. It is commonly used in the treatment of organic matter in wastewater, seawater desalination, heavy metal removal and other well-known processes. However, there is no precedent for using electric adsorption technology to treat emulsified wastewater.

[0005] Biomass charcoal-based materials are often used in the adsorption field. Biomass has a natural porous structure, a large specific surface area, good electrical conductivity after carbonization, and the advantages of large-scale production and low cost. Biochar is often used in capacitive deionization technology and supercapacitors. SUMMARY

[0006] In order to solve the above problems existing in the prior art demulsification technology, the present application provides a biomass charcoal-based material electrode electric adsorption demulsification method, which uses low-cost, easily available, high-volume, renewable resource biomass as the material of the electrode, modifies and incorporates metal to increase its electrical conductivity and pollutant adsorption active sites, and based on the principle of electric adsorption, demulsification and oil removal are carried out at the same time.

[0007] The first object of the present application is to provide a biomass charcoal-based material electrode electric adsorption demulsification method, which uses biomass charcoal as the electrode, two electrode plates are symmetrically and parallelly placed and inserted into the emulsion, and low voltage is applied to treat various emulsified wastewater.

[0008] The specific technical solution is:

[0009] A method for demulsification by electro-sorption based on biomass charcoal material electrode: using biomass charcoal material as electrode, applying voltage on the electrode to demulsify and remove oil from oil-containing emulsified wastewater.

[0010] Preferably, the electrode is an intact piece of biomass which has not been broken and recombined, and the biomass is directly used as an electrode after hydrothermal solution hydrothermal treatment and carbonization treatment.

[0011] Preferably, the electro-sorption method uses low-voltage direct current, and the voltage is 1-10V.

[0012] Preferably, the oil-containing emulsified wastewater is emulsion.

[0013] Preferably, the hydrothermal solution contains Fe 3+ and Ni 2+ , and the molar ratio is 1:1-1:4.

[0014] Preferably, the Fe 3+ and Ni 2+ are derived from ferric sulfate and nickel chloride, respectively.

[0015] Preferably, the hydrothermal solution contains D-(+)-glucosamine hydrochloride, and the concentration of the D-(+)-glucosamine hydrochloride is 100g / L.

[0016] Preferably, the biomass is soaked in an acetone solution containing 2,3-dihydroxynaphthalene after hydrothermal treatment, and then dried and carbonized; the concentration of the 2,3-dihydroxynaphthalene is 12.5g / L.

[0017] Preferably, the hydrothermal temperature is 180℃.

[0018] Preferably, the carbonization treatment is: 350℃ for 2h, and then 1000℃ for 2h.

[0019] Another object of the present application is to provide a preparation method of the above-mentioned biomass charcoal material electrode: the biomass is doped with metal atoms through a hydrothermal reaction, super-pure water containing Fe 3+ and Ni 2+ is used as a hydrothermal solution, and D-(+)-glucosamine hydrochloride and 2,3-dihydroxynaphthalene reagents are used to better fix the metal on the wood during carbonization, and finally a metal-doped biomass electrode is prepared by carbonization, which is recorded as NiFe / CW electrode.

[0020] Preferably, birch biomass is selected as the material for preparing the electrode.

[0021] Preferably, the Fe 3+ and Ni2+ The molar ratio is 1:1.

[0022] Preferably, the concentration of D-(+)-glucosamine hydrochloride is controlled at 100 g / L.

[0023] Preferably, the 2,3-dihydroxynaphthalene reagent is dissolved in acetone solution at a concentration of 12.5 g / L.

[0024] The beneficial effects of this invention are:

[0025] This invention uses whole biomass char-based materials as electrodes, combining inexpensive, readily available, naturally porous biomass char materials with excellent adsorption performance with electroadsorption technology. Under low voltage, it performs electroadsorption demulsification and oil removal treatment on oily emulsified wastewater. While efficiently demulsifying, it also significantly adsorbs and removes organic matter from the emulsified wastewater. This demulsification method has the advantages of low cost, abundant and readily available electrode raw materials, low energy consumption, high efficiency, no secondary pollution, and regenerable electrodes. Attached Figure Description

[0026] To more clearly illustrate the technical solution of the present invention, the accompanying drawings required by the present invention will be briefly introduced below.

[0027] Figure 1 This is a SEM image of the NiFe / CW electrode.

[0028] Figure 2 The image shows the XRD pattern of the NiFe / CW electrode.

[0029] Figure 3 This is the XPS spectrum of the NiFe / CW electrode.

[0030] Figure 4 This is a BJH pore size distribution diagram of the NiFe / CW electrode.

[0031] Figure 5 The N2 adsorption-desorption isotherm is shown for the NiFe / CW electrode.

[0032] Figure 6 The diagram shows the apparatus for the demulsification experiment, where 1, 2, and 3 represent the experimental group, control group, and blank group, respectively.

[0033] Figure 7 The demulsification experiment of Example 1 is shown in Figure (a), which is a line graph of the transmittance of toluene emulsion changing with time, and Figure (b) is the toluene removal rate when each group of samples is completely demulsified (transmittance reaches 90%).

[0034] Figure 8 The cyclic demulsification experiment of Example 2 is shown in Figure (a), which is a line graph of the transmittance of toluene emulsion in each cycle as a function of time, and Figure (b) is the toluene removal rate in each cycle.

[0035] Figure 9 The demulsification experiment in Example 3 shows that Figure (a) is a line graph of the transmittance of the toluene emulsion changing over time, and Figure (b) shows the toluene removal rate when the two groups of samples were completely demulsified.

[0036] Figure 10 The demulsification experiment in Example 4 shows that Figure (a) is a line graph of the transmittance of toluene emulsion changing over time, and Figure (b) shows the toluene removal rate when each group of samples is completely demulsified.

[0037] Figure 11 The demulsification experiment of Example 5 is shown in Figure (a), which is a line graph showing the change of light transmittance of toluene microemulsion over time, and Figure (b) shows the removal rate of toluene in the demulsification experiment.

[0038] Figure 12 This is a line graph showing the change in light transmittance of the cutting fluid emulsion over time during the demulsification experiment in Example 6.

[0039] Figure 13 (a) shows the COD removal rate in the demulsification experiment of Example 6, and (b) shows the corresponding metal ion removal rate.

[0040] Figure 14 This is a line graph showing the change in light transmittance of the cutting fluid emulsion over time during the cyclic demulsification experiment in Example 7.

[0041] Figure 15 (a) shows the COD removal rate in the cyclic demulsification experiment of Example 7, and (b) shows the corresponding metal ion removal rate.

[0042] Figure 16 This is a line graph showing the change in light transmittance of the cutting fluid microemulsion over time during the demulsification experiment in Example 8.

[0043] Figure 17 (a) shows the COD removal rate in the demulsification experiment of Example 8, and (b) shows the corresponding metal ion removal rate. Detailed Implementation

[0044] The following is in conjunction with the appendix Figures 1-17 The embodiments and examples are described in detail to illustrate specific implementations of the present invention. They are only used to provide further explanation of the present invention and do not constitute a limitation on the present invention.

[0045] The emulsion used in this invention for testing the electroadsorption demulsification performance of the electrode has a volume of 18 mL. The emulsion is simulated wastewater prepared in the laboratory, and the electrochemical workstation serves as the device providing the voltage.

[0046] The birch biomass electrode used for testing in this invention has dimensions of 3.5 × 1.2 × 0.2 cm. 3 The two parallel electrode plates weigh 0.65g.

[0047] The demulsification reaction of this invention is carried out under magnetic stirring at a speed of 100 rpm and at room temperature (25°C).

[0048] A method for preparing a biomass carbon-based electrode is as follows:

[0049] 1. Cut the soaked birch wood into pieces measuring 5.0 × 1.5 × 0.3 cm. 3 (Radial × Chordal × Longitudinal) thin slices; 2. D-glucosamine hydrochloride (GlcN, 10.00 g) was dissolved in 100 mL of ultrapure water, and Fe2(SO4)3·7H2O (1.00 g) and NiCl2·6H2O (1.19 g) were dissolved and sonicated for 0.5 h; 3. Birch wood was transferred to a hydrothermal reaction solution and sonicated for 0.5 h; 4. The above solution containing birch wood was reacted in a reactor at a high temperature and high pressure of 180 °C for 15.0 h; 5. Hydrothermal After the reaction, the birch wood surface was rinsed with ultrapure water and acetone, respectively. Then, the birch wood was completely immersed in an acetone solution containing 12.5 g / L of 2,3-dihydroxynaphthalene, and the hydrothermally heated birch wood was kept in a vacuum for 12.0 h using a vacuum filtration pump. 6. The treated birch wood was freeze-dried at -50°C for 12.0 h in a freeze dryer. 7. Finally, under a N2 protective atmosphere, the birch wood was carbonized in a tube furnace at 350°C for 3.0 h and at 1000°C for 2.0 h. This yields the NiFe / CW electrode (i.e., a biomass carbon-based electrode doped with metallic NiFe). It should be noted that this invention is not limited to the doping of these two metals.

[0050] Figure 1 The SEM image of the NiFe / CW electrode reveals a porous structure with macropores and hierarchical arrangement, and numerous white particles are evenly scattered on the cell walls of the wood. These particles exhibit relatively regular spherical and rod-shaped shapes, with particle sizes at the nanometer level.

[0051] Figure 2 The image shows the XRD pattern of the NiFe / CW electrode, whose diffraction peaks are consistent with the standard card, confirming the synthesis of the biomass carbon-based electrode doped with metallic Ni and Fe.

[0052] Figure 3 The image shows an XPS image of a NiFe / CW electrode, which reveals that the total metal atom content is approximately 3.2%, indicating trace metal doping. The C content is as high as 88.37%, and the O / C ratio is only 0.06. The low O / C ratio indicates that due to the high degree of carbonization and the loss of polar functional groups at higher temperatures, the biochar surface is more aromatic and less hydrophilic, making it easier to adsorb organic matter from wastewater.

[0053] Figure 4This is the HJH pore size distribution diagram of the NiFe / CW electrode, showing that the electrode pores exhibit predominantly micropore characteristics.

[0054] Figure 5 The N2 adsorption-desorption isotherm of the NiFe / CW electrode exhibits a typical type IV hysteresis loop, indicating the presence of mesoporous structures in the electrode.

[0055] Figure 6 The demulsification experiment setup consisted of two NiFe / CW electrodes separated by a 1.5mm thick insulating gasket. Experimental, control, and blank groups were set up (i.e., 1, 2, and 3 in the figure). In the experimental group, a voltage was applied to the electrodes; in the control group, only the electrodes were placed on the samples without voltage application; and in the blank group, no electrodes were placed on the samples. Parallel control experiments were used to highlight the electroadsorption demulsification performance of the electrodes. The IVIUM electrochemical workstation was computer-controlled and connected to the copper wires on the electrodes via electrode clamps. The electrodes were vertically inserted into a reactor containing 18mL of the wastewater sample to be treated. A sampling port was set up, and the reactor was sealed. The two copper wires on the electrodes and the sampling port extended from three holes in the lid to prevent wastewater evaporation. The demulsification experiment was conducted at 100rpm using a magnetic stirrer.

[0056] Applications of biomass electrodes in demulsification and oil removal:

[0057] Example 1

[0058] Emulsified wastewater with a toluene concentration of 1% stabilized by the neutral surfactant Tween 20 (0.5 g / L) was treated using NiFe / CW electrodes at different low voltages.

[0059] Figure 7 (a) is a line graph showing the change of transmittance of toluene emulsion with time in Example 1. It can be seen that the transmittance increases with the increase of demulsification time, and the increase trend is more obvious with higher voltage. In particular, the transmittance reaches 90% at 2.3h when demulsification is carried out at 1.5V (that is, the toluene emulsion is completely demulsified). Figure 7 (b) The toluene removal rate when each group of samples is completely demulsified (transmittance reaches 90%), and the removal rate of each group is above 95%. Moreover, the toluene removal rate gradually increases with the increase of voltage.

[0060] Example 2

[0061] The emulsified wastewater from Example 1 was treated using a NiFe / CW electrode at 1.5V to test the electrode's performance in demulsification and oil removal. After each cycle, the electrode was rinsed with sufficient pure water, soaked for 12 hours, and then the next cycle was performed.

[0062] Figure 8 Example 2 was used to test the cyclic demulsification performance of the NiFe / CW electrode. Figure 8(a) shows the change in transmittance of the electrode over time after three cycles at a voltage of 1.5V. It can be seen that after three cycles, complete demulsification can still be achieved within 4 hours. Figure 8 (b) shows the toluene removal rate after three cycles. It can be seen that after three cycles, the toluene removal rate is still higher than 98%. This demonstrates the excellent cyclic demulsification effect of the electrode under low voltage.

[0063] Example 3

[0064] Emulsified wastewater with a toluene concentration of 1% was treated using a NiFe / CW electrode at a voltage of 1.5V, stabilized by anionic surfactant SDS (0.5 g / L) and cationic surfactant CTAB (0.5 g / L).

[0065] Figure 9 (a) is a line graph showing the change of light transmittance over time in the demulsification experiment of Example 3. The trend is almost similar to the demulsification process of the Tween20 stable emulsion. Complete demulsification can be achieved in no more than 3.5 hours at a voltage of 1.5V. Figure 9 (b) shows the toluene removal rate when the two groups of samples were completely demulsified, and the removal rate was above 98%.

[0066] Examples 1, 2, and 3 demonstrate that this method can be used to treat low-concentration toluene emulsified wastewater stabilized by different types of surfactants, and that the electrode exhibits good cyclic demulsification performance.

[0067] The electrical energy consumed in demulsification, toluene electroadsorption capacity, and specific energy consumption in the demulsification experiments of Examples 1, 2, and 3 were detected and calculated. The specific data are shown in Table 1.

[0068] Table 1. Results of performance tests related to demulsification experiments in Examples 1-3

[0069]

[0070] In the final examples 1, 2, and 3, the NiFe / CW electrodes all achieved a toluene electroadsorption capacity of approximately 200 mg / g, with the electrical energy consumed during demulsification on the order of 10. -5 Below kWh, the specific energy consumption is less than 0.040 kWh / kg. This demonstrates the advantages of the invention's low-voltage demulsification: low energy consumption, high organic matter electroadsorption capacity of the electrode, low specific energy consumption, and good electrode cycle performance.

[0071] Example 4

[0072] Emulsified wastewater with a toluene concentration of 5% and Tween 20 (concentration of 0.5 g / L) was treated using NiFe / CW electrodes at different voltages.

[0073] Figure 10(a) is a line graph showing the change in transmittance over time in Example 4. It can be seen that demulsification becomes more difficult as the oil concentration increases. However, when the voltage is increased to 5V, demulsification has a significant effect, and complete demulsification can be achieved in 3.4h, while the transmittance of the emulsified wastewater in the demulsification experiment with a voltage of 1.5V is only 27%. Figure 10 (b) is the toluene removal rate when the 5V experimental group was completely demulsified, at which point the toluene removal rate reached 97.97%.

[0074] The demulsification energy consumption at 5V in Example 4 is only 1.19 × 10⁻⁶. -5 kWh, and can obtain 1183 mg g -1 The toluene electroadsorption capacity and 0.015 kWh / kg -1 The specific energy consumption indicates that the invention can be used to treat emulsified wastewater with high oil concentration by increasing the voltage, and it has low energy consumption and low specific energy consumption.

[0075] Example 5

[0076] Tween 20 / n-butanol-stabilized toluene-containing microemulsion wastewater was treated using NiFe / CW electrode electroadsorption demulsification.

[0077] Figure 11 (a) is a line graph showing the change of light transmittance over time in Example 5. When the demulsification voltage is increased to 5V, there is obvious demulsification in a short time, and complete demulsification can be achieved within 7 hours. Figure 11 (b) The figure shows the toluene removal rate when the emulsion was completely demulsified in each group of experiments. More than 90% of the toluene removal rate was obtained at 5V voltage.

[0078] In Example 5, the power consumption was 1.85 × 10⁻⁶. -4 kWh, yielding 226 mg g -1 The toluene electroadsorption capacity and 1.259 kWh / kg -1 The specific energy consumption indicates that this invention can be used not only to treat toluene emulsion wastewater, but also to treat toluene microemulsion wastewater with toluene as the main oil phase.

[0079] Example 6

[0080] The emulsified wastewater from copper machining cutting fluids, containing varying concentrations of metal ions and oil phases, was treated using a NiFe / CW electrode at 10V via electroadsorption demulsification. The main pollutants in the cutting fluid wastewater were polycyclic aromatic hydrocarbons, long-chain hydrocarbons, and heavy metal ions.

[0081] Figure 12This is a line graph showing the transmittance as a function of time in Example 6. The data indicates that as the concentration of metal ions in the cutting fluid increases, the demulsification time will be prolonged, but complete demulsification can eventually be achieved within 5 hours. Furthermore, increasing the oil phase concentration of the cutting fluid emulsion wastewater from 5% to 10% also achieves complete demulsification within 10 hours.

[0082] Figure 13 (a) and (b) show the COD removal rate and metal ion removal rate of the cutting fluid after complete demulsification in Example 6, respectively. It can be seen that demulsification of the 5% oil concentration cutting fluid in less than 5 hours can achieve a COD removal rate of over 90% and a metal ion removal rate of over 95%. Although the demulsification time for the 10% oil concentration cutting fluid is longer, its COD removal rate is close to 95%, and its metal ion removal rate is nearly 99%. This demonstrates that this method can be used to treat cutting fluids with higher oil concentrations and also shows excellent performance in electro-adsorption removal of metal ions.

[0083] Example 7

[0084] The cycling performance of a NiFe / CW electrode during demulsification was tested at 10V. The target emulsion was Cu. 2+ The concentration is 25 mg / L -1 Cutting fluid emulsion wastewater with an oil phase concentration of 5%. After each cycle, the electrodes are soaked in sufficient formic acid for 12 hours to dissolve as many contaminants as possible. Afterward, the electrodes are rinsed and soaked with high-temperature pure water to remove the formic acid on the electrodes in preparation for subsequent cycles.

[0085] Figure 14 The image shows the change in transmittance over time in the cyclic demulsification experiment of the NiFe / CW electrode in Example 7. It can be seen that complete demulsification can be achieved within 10 hours in the third cycle.

[0086] Figure 15 (a) COD removal rate after three cycles following complete demulsification in Example 7 Figure 15 (b) shows the metal ion removal rate after three cycles following complete demulsification. It can be seen that after three cycles, the COD removal rate remains above 88%, and the metal ion removal rate is above 97%, demonstrating excellent cyclic performance.

[0087] Furthermore, the electrical energy consumed in each group of experiments in Examples 6 and 7 was only on the order of 10. -4 √10 -3 kWh, and the specific energy consumption is all in the range of 2kWh kg. -1 The specific data is shown in Table 2 below.

[0088] Table 2. Performance test results of demulsification experiments in Examples 6-7

[0089]

[0090] Table 2 shows that this demulsification technology can treat cutting fluid emulsion wastewater with low energy consumption and low specific energy consumption.

[0091] Example 8

[0092] Cutting fluid microemulsion wastewater was treated by electroadsorption demulsification using a NiFe / CW electrode at 10V. The composition of the cutting fluid microemulsion wastewater was almost similar to that of cutting fluid emulsion wastewater.

[0093] Figure 16 This is a line graph showing the change in transmittance over time during the experiment in Example 8. The data indicates that the presence of metal increases the demulsification time.

[0094] Figure 17 (a) and Figure 17 (b) COD removal rate and metal ion removal rate of the cutting fluid microemulsion after complete demulsification in Example 8, respectively. The COD removal rate of both groups of samples was higher than 90%. 10V-5%-25mg L -1 Cu 2+ The metal ion removal rate in the experimental group was close to 99%.

[0095] In the experiment of treating cutting fluid microemulsions with NiFe / CW electrodes, similar results were obtained as in Example 6, with low power consumption and low specific energy consumption. Specific data are shown in Table 3.

[0096] Table 3. Performance test results of demulsification experiment in Example 8

[0097]

[0098] Table 3 shows that this demulsification technology can be used to treat cutting fluid microemulsion wastewater.

[0099] The above embodiments are only for verifying the demulsification and oil removal method of the present invention and the demulsification and oil removal performance of the prepared biomass carbon-based electrode. However, the demulsification and oil removal method of the present invention is not limited to the above embodiments.

Claims

1. A method for electro-sorption demulsification based on biomass char-based material electrodes, characterized in that, The biomass charcoal-based material is used as an electrode, and a voltage is applied to the electrode to demulsify and remove oil from oil-containing emulsified wastewater; the electrode is an intact piece of biomass that has not been broken and recombined, and the biomass is directly used as an electrode after being subjected to hydrothermal solution hydrothermal treatment and carbonization treatment; The hydrothermal solution contains D-(+)-glucosamine hydrochloride, and the concentration of the D-(+)-glucosamine hydrochloride is 100 g / L; the biomass is soaked in an acetone solution containing 2,3-dihydroxynaphthalene after being subjected to hydrothermal treatment, and is dried and subjected to carbonization treatment; the concentration of the 2,3-dihydroxynaphthalene is 12.5 g / L.

2. The method of biomatrix charcoal-based material electrode electrosorption demulsification according to claim 1, characterized in that, The electro-adsorption method uses low-voltage direct current, and the voltage is 1-10 V.

3. The electroadsorption demulsification method based on biomass char-based material electrodes according to claim 1, characterized in that, The oil-containing emulsified wastewater is emulsion.

4. The method of claim 1, wherein the biomass-based carbon material is selected from the group consisting of activated carbon, activated carbon cloth, activated carbon felt, activated carbon paper, activated carbon aerogel, activated carbon xerogel, and combinations thereof. The hydrothermal solution contains Fe 3+ and Ni 2+ in a molar ratio of 1 : 1 to 1 :

4.

5. The method of claim 4, wherein the biomass-based carbon material is selected from the group consisting of activated carbon, activated carbon cloth, activated carbon felt, activated carbon paper, and combinations thereof. The Fe3+ and Ni2+ are derived from iron sulfate and nickel chloride, respectively.

6. The method of biomatrix charcoal-based material electrode electrosorptive demulsification according to claim 1, characterized in that, The hydrothermal temperature is 180 DEG C.

7. The electroadsorption demulsification method based on biomass char-based material electrodes according to claim 1, characterized in that, The carbonization treatment is: 350 DEG C for 2 h, and then 1000 DEG C for 2 h of carbonization.

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