A modified multiphase filler and its application in removing hydrophobic organic pollutants

Abstract

The present invention relates to a modified multiphase filler and its application in removing hydrophobic organic pollutants, which can be used as a high-performance filler to solve problems such as existing silicone oil foaming and short service life. The present invention uses means such as physical doping, chemical modification, high-temperature oxygen isolation thermalization and adsorption filling, and realizes the shaping of the filler skeleton through processes such as polyurethane prepolymer melting, granulation, foaming, and shaping; the free-state silicone oil molecules are filtered out by the drying method, and the bound silicone oil is locked inside the filler. The present invention increases the surface roughness and internal porosity of the substrate. It not only forms loose voids and air flow paths macroscopically to optimize the uniform distribution of gas-liquid and biofilms; but also strengthens the hydrophobicity, dispersibility and stability of silicone oil between its internal pores microscopically, which further consolidates the stability of the "gas-water-silicone oil-biology" multiphase system and ultimately improves the overall efficiency. The production raw materials of the present invention are easily available and the cost is low, and it can be popularized to the purification treatment of various hydrophobic organic pollutants.

Description

(1) Technical Field

[0001] The present invention relates to a modified multiphase filler and its application in removing hydrophobic organic pollutants. (2) Background Art

[0002] With the continuous development of the chemical industry, the use of organic solvents has become increasingly widespread. They can be used as chemical intermediates, solvent bodies, and organic chemical raw materials in industrial production, and are widely used in organic synthesis industries such as chemical engineering, papermaking, printing, pharmaceutical chemistry, and plastics. For high-concentration organic toxic pollutants, the two-phase partitioning technology is considered a powerful technology for removing hydrophobic organic pollutants. This technology increases the non-aqueous phase in the original phase to accelerate the mass transfer rate of hydrophobic waste gas, thereby improving the biological removal effect of organic waste gas.

[0003] At present, non-aqueous phase media can be divided into liquid media and solid phase media. Due to the disadvantages of liquid non-aqueous phase such as easy foaming, high cost, large loss, and difficulty in large-scale application; while the solid non-aqueous phase can offset the disadvantages of the liquid non-aqueous phase, but it also has the characteristics of relatively larger particles than the liquid non-aqueous phase particles and easy sedimentation, and the corresponding degradation effect is weaker than that of the aqueous phase. The advantages of high molecular polymers are as follows: having the ability to adsorb small molecule compounds; having hydrophobicity and biocompatibility, high affinity for target organic pollutants; not easily biodegradable; low price; easy to separate and recycle; not easily adsorbed on the reactor wall and easy to remove.

[0004] In order to reduce the foaming and difficult recyclability of the liquid non-aqueous phase, for example, the Chinese invention patent CN106365324A can efficiently recycle the non-aqueous phase, while CN110746639B only increases the hydrophobicity of its material. These measures can recycle the non-aqueous phase to a certain extent, but after long-term use, some of the non-aqueous phase has a foaming phenomenon, the corresponding oil phase is difficult to incorporate water, the oil-water interface is difficult to mix, and there is still a certain loss. The modified multiphase filler can better fix the non-aqueous phase and well alleviate similar problems. It has a lower production cost and stronger stability, and can continuously enhance the biodegradation of waste gas. (3) Summary of the Invention

[0005] The purpose of the present invention is to provide a modified multiphase filler and its application in removing hydrophobic organic pollutants, to solve the problem of easy foaming in the use of silicone oil in the prior art, and to extend its service life.

[0006] The technical solution adopted by the present invention is:

[0007] A modified multiphase filler is obtained by the following method:

[0008] (1) Mix a polyurethane prepolymer with carbon powder and starch to make a prefabricated mixture;

[0009] (2) The prefabricated mixture is screened, melt-blended, and granulated to obtain uniform particles;

[0010] (3) The generated particulate matter is secondary-mixed, plasticized, injection-molded, foamed, and shaped to obtain polyurethane foam;

[0011] (4) The polyurethane foam is successively placed in alcohol solution, acid solution, and alkali solution for impurity removal, and then dried;

[0012] (5) The dried polyurethane foam is soaked in a ferric chloride solution with a mass concentration of 15 - 45% for 10 - 18 h, so that the voids therein adsorb and fill the iron salt solution;

[0013] (6) After high-temperature anaerobic thermal treatment at 100 - 200 °C for 20 - 60 min, it is then cooled to room temperature;

[0014] (7) The cooled polyurethane foam is soaked in silicone oil for 20 - 100 h, and dried at 30 - 40 °C for 12 - 18 h to obtain the modified multiphase filler.

[0015] The present invention mainly introduces measures of chemical modification, high-temperature anaerobic thermal treatment, and adsorption filling on the basis of polyurethane melt molding, removes most of the liquid silicone oil by long-term static drying, and retains the bound silicone oil particles between the fillers, thereby obtaining the modified multiphase filler in this way.

[0016] Specifically, the mass ratio of the polyurethane prepolymer, carbon powder, and starch is 1:0.05 - 1.0:0.01 - 2.0.

[0017] In step (2), the prefabricated mixture is put into a melt-blending machine for melt-blending and granulation. The melt-blending and pressure-holding time are fixed at 0.5 - 15 s, the cooling time is 0.2 - 5.0 s, the pressure is 5 - 10 MPa, and the ambient temperature is maintained at 50 - 100 °C; then the generated particulate matter is transferred to a screw machine for plasticization treatment at 80 - 150 °C, and then injected into a mold and heated to 140 - 210 °C for foaming for 5 - 30 min, and finally heat-treated and shaped at 40 - 80 °C to obtain polyurethane foam.

[0018] Preferably, in step (3), the alcohol solution is an ethanol solution with a volume concentration of 30% - 75%, and the soaking time is 5 - 30 min. Soaking the polyurethane in ethanol with a concentration of 30% - 75% for 5 - 30 min can remove the organic impurities therein.

[0019] Preferably, in step (3), the acid solution has a mass concentration of 5% - 25%, and the acid generally uses inorganic acid, which can be nitric acid, or sulfuric acid, or hydrochloric acid.

[0020] Preferably, the lye in step (3) has a mass concentration of 10% to 30%, and the alkaline solution can be sodium hydroxide solution, or potassium hydroxide solution, or sodium carbonate solution.

[0021] The degradation ability of the modified multiphase composite filler of the present invention is stronger than that of general fillers, such as ordinary hollow balls, etc. The removal rate can be increased by 5.0% to 30%. Under low-concentration conditions, the corresponding removal rate can reach more than 90%.

[0022] The present invention also relates to the application of the modified multiphase filler in removing hydrophobic organic pollutants.

[0023] Preferably, the hydrophobic organic pollutant is chlorobenzene.

[0024] The beneficial effects of the present invention are mainly reflected in: (1) By adjusting the modification process, the roughness of the surface of the modified filler is increased, the internal porosity is increased, and the absorption effect on silicone oil is strengthened; (2) Through a specifically strengthened adsorption process, the fixation degree of the non-aqueous phase inside the modified filler is strengthened, so that the whole can be used as a non-aqueous phase medium in the reactor (because the filler adsorbs the non-aqueous phase. When part of the free liquid escapes under the action of gravity and resistance, the combined liquid is fixed in the filler. At this time, the mixed filler can be used as a non-aqueous phase); (3) Avoid the independent fixed model of the solid non-aqueous phase, broaden the distribution area between the non-aqueous phase inside the filler and the macromolecular particles, further strengthen the fluidity between it and the microorganisms, increase the contact frequency and contact space with the microorganisms on the side, and then strengthen the corresponding degradation effect, and finally improve the overall removal rate of the system. (IV) Description of the Drawings

[0025] Figure 1 It is a flow chart of the modification production process;

[0026] Figure 2 It is the morphology of silicone oil before and after using the filler;

[0027] Figure 3 It is a graph of the change in the degradation rate of the multiphase filler and the ordinary filler in the shake flask experiment;

[0028] Figure 4 It is a graph of the change in the concentration of carbon dioxide of the multiphase filler and the ordinary filler in the shake flask experiment;

[0029] Figure 5 It is a graph of the change in the concentration of extracellular protein (PN) of microorganisms in the water phase and on the filler in the shake flask experiment;

[0030] Figure 6 It is a graph of the change in the dehydrogenase activity (DHA) of microorganisms in the water phase and on the filler in the shake flask experiment;

[0031] Figure 7It is the graph of the degradation rate change of multi-phase filler and ordinary filler during the startup period;

[0032] Figure 8 It is the graph of the degradation rate change of multi-phase filler and ordinary filler during the starvation period;

[0033] Figure 9 It is the graph of the instantaneous change of the degradation rate of multi-phase filler and ordinary filler under high load;

[0034] Figure 10 It is the configuration diagram of the biotrickling filter tower. (V) Specific implementation manners

[0035] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0036] Embodiment 1:

[0037] See the process flow chart in Figure 1 , and the specific steps are as follows:

[0038] (1) Mix 20 kg of ordinary polyurethane prepolymer (TDI polyester polyether type, Shandong Shuntai Chemical Technology Co., Ltd.), 1 kg of carbon powder and 2 kg of starch after passing through a 100-mesh sieve, and stir for 4 h.

[0039] (2) Put the prepared mixture into a melting granulator for melting and granulation. The melting and pressure-holding time is fixed at 0.5 s, the cooling time is 1.0 s, the pressure is 5 MPa, and the ambient temperature is maintained at 70 °C. Then transfer the generated particles into a screw machine for plasticizing treatment at 80 °C, and then inject them into a mold and foam at 180 °C for 10 min. Finally, heat-treat and shape at 60 °C to obtain polyurethane foam.

[0040] (3) Immerse the polyurethane foam in 45% ethanol for 5 min to remove the organic impurities therein.

[0041] (4) Remove the alkaline and acidic impurities therein by washing with 5% acid (sulfuric acid) and 10% alkali (sodium hydroxide) respectively, and dry.

[0042] (5) Adsorb and fill a large amount of iron salt solution in the voids by soaking in 15% ferric chloride solution at 35 °C for 10 h.

[0043] (6) Keep it at 120 °C for high-temperature anaerobic heat treatment for 40 min, which can increase the porosity therein and enhance the corresponding hydrophobicity, and then cool it to room temperature.

[0044] (7) Immerse the cooled polyurethane foam in silicone oil for 20 h, and keep the obtained filler at 40 °C for 18 h to remove most of the liquid free silicone oil while retaining the bound silicone oil, finally obtaining the modified multiphase filler.

[0045] Example 2:

[0046] Mix 40 kg of ordinary polyurethane prepolymer with 3 kg of carbon powder (after passing through a 100-mesh sieve) and 8 kg of starch, etc., and stir for 8 h.

[0047] Put the prepared premix into a melt mixer for melt granulation. The melt and pressure holding time is fixed at 1.0 s, the cooling time is 2.0 s, the pressure is 6 MPa, and the ambient temperature is kept at 70 °C. Then transfer the generated particles into a screw machine for plasticizing treatment at 90 °C, and then inject them into a mold and heat them to 170 °C for foaming for 5 min. Finally, heat-treat and shape at 50 °C to obtain polyurethane foam.

[0048] Immerse the polyurethane foam in 55% ethanol for 15 min to remove the organic impurities therein. Use 15% acid (hydrochloric acid) and 20% base (potassium hydroxide) for cleaning respectively to remove the alkaline and acidic impurities therein and then dry.

[0049] Use 25% ferric chloride to soak at 45 °C for 30 h to adsorb and fill a large amount of ferric salt solution in the voids therein.

[0050] Keep it at 150 °C for high-temperature anaerobic thermal treatment for 80 min, which can increase the porosity therein and enhance the corresponding hydrophobicity, and then cool it to room temperature.

[0051] Immerse the cooled polyurethane foam in silicone oil for 40 h, and keep the obtained filler at 140 °C for 90 h to remove most of the liquid free silicone oil while retaining the bound silicone oil, finally obtaining the modified multiphase filler.

[0052] Example 3:

[0053] Mix 80 kg of ordinary polyurethane prepolymer with 3 kg of carbon powder (after passing through a 100-mesh sieve) and 20 kg of starch, etc., and stir for 6 h.

[0054] Put the prepared premix into a melt mixer for melt granulation. The melt and pressure holding time is fixed at 1.5 s, the cooling time is 3.0 s, the pressure is 8 MPa, and the ambient temperature is kept at 85 °C. Then transfer the generated particles into a screw machine for plasticizing treatment at 75 °C, and then inject them into a mold and heat them to 190 °C for foaming for 15 min. Finally, heat-treat and shape at 65 °C to obtain polyurethane foam.

[0055] The polyurethane foam was immersed in 65% ethanol for 23 min to remove the organic impurities therein. The basic and acidic impurities were removed by washing with 20% acid (nitric acid) and 25% base (sodium hydroxide) respectively, and then dried.

[0056] A large amount of iron salt solution was adsorbed and filled into the voids by soaking in 35% ferric chloride at 55 °C for 50 h.

[0057] Thermal oxidation was carried out at 180 °C under high temperature and oxygen-free conditions for 100 min, which could increase the porosity and enhance the corresponding hydrophobicity, and then it was cooled to room temperature.

[0058] The cooled polyurethane foam was immersed in silicone oil for 60 h, and the obtained filler was dried at 60 °C for 150 h to remove most of the liquid free silicone oil, while retaining the bound silicone oil, and finally the modified multiphase filler was obtained.

[0059] Example 4:

[0060] Ordinary polyurethane prepolymer (80 kg) was mixed and stirred with carbon powder (6 kg) and starch (30 kg) passed through a 100-mesh sieve for 10 h.

[0061] The prepared premix was put into a melt mixer for melting and granulation. The melting and pressure holding time was fixed at 2.0 s, the cooling time was 4.0 s, the pressure was 10 MPa, and the ambient temperature was maintained at 95 °C. Then the generated particles were transferred to a screw machine for plasticization at 85 °C, and then injected into a mold and foamed at 160 °C for 20 min, and finally heat-treated and shaped at 55 °C to obtain polyurethane foam.

[0062] The polyurethane was immersed in 75% ethanol for 30 min to remove the organic impurities therein. The basic and acidic impurities were removed by washing with 25% acid (sulfuric acid) and 30% base (sodium carbonate) respectively, and then dried.

[0063] Thermal oxidation was carried out at 200 °C under high temperature and oxygen-free conditions for 40 min, which could increase the porosity and enhance the corresponding hydrophobicity, and then it was cooled to room temperature.

[0064] The cooled polyurethane foam was immersed in silicone oil for 80 h, and the obtained filler was dried at 80 °C for 180 h to remove most of the liquid free silicone oil, while retaining the bound silicone oil, and finally the modified multiphase filler was obtained.

[0065] Example 5:

[0066] (1) Detection of distribution coefficient in multiphase distribution system:

[0067] The partition coefficient in a multiphase distribution system refers to the concentration ratio of components in the three phases when the target substrate reaches equilibrium among the gas phase, liquid phase, and non-aqueous phase under certain conditions. The partition coefficients of chlorobenzene in the gas-nonaqueous phase and water phase / nonaqueous phase were measured in a 250 mL anaerobic bottle, and three parallel experiments were set up. 5 mL of the modified multiphase packing prepared according to the method of Example 1 was added to the anaerobic bottle, and 1, 5, 10, 15, 20, and 25 μL of chlorobenzene were added. The bottle mouth was sealed with a polytetrafluoroethylene stopper and stirred in a shaker for 2 h. Using the static headspace method, the concentration of chlorobenzene in the gas phase was measured by gas chromatography, and then the concentration of chlorobenzene in the modified multiphase packing was calculated according to the mass balance. The slope of the obtained curve was the partition coefficient of chlorobenzene in the gas phase / nonaqueous phase. The determination of the partition coefficient of chlorobenzene in the water phase / nonaqueous phase was the same. The anaerobic bottle was filled with an inorganic salt medium and 5 mL of the modified multiphase packing prepared according to the method of Example 1. After adding 1, 5, 10, 15, 20, and 25 μL of chlorobenzene, the bottle mouth was sealed with a polytetrafluoroethylene stopper and stirred in a shaker for 2 h to make it completely mixed. Then the anaerobic bottle was left standing for 3 h. The concentration of chlorobenzene in the water phase was measured by liquid chromatography, and then the concentration of chlorobenzene in the multiphase packing was calculated based on the mass balance. The slope of the obtained curve was the partition coefficient of chlorobenzene in the water phase / SNAP. According to the experimental results, the partition coefficients of chlorobenzene between the gas phase / SNAP and water phase / SNAP can be obtained respectively, and then the partition coefficient of chlorobenzene among the gas phase / water phase / S three phases can be obtained.

[0068] The partition coefficients of chlorobenzene among the multiphase packing, liquid phase, and gas phase are shown in Table 1:

[0069] Table 1: Partition coefficients of chlorobenzene among the multiphase packing, liquid phase, and gas phase

[0070] Phase Partition coefficient <![CDATA[R 2 > Water 0.26 0.993 Initial multiphase packing 0.0014 0.991 Multiphase packing used for 200 days 0.0086 0.896

[0071] (2) Optical microscope analysis of the samples:

[0072] The appearance morphology of the packing before and after treatment under a scanning electron microscope and the silicone oil in the packing before and after use are as Figure 2 shown.

[0073] Figure 2 In 2-A, it represents the appearance morphology of the packing before use under an optical microscope, Figure 2 and in 2-B, it represents the appearance morphology of the packing after running for 250 days under an optical microscope. From Figure 2 the analysis and comparison, it can be known that after running for a period of time, there is still a certain amount of liquid silicone oil component in the modified packing. Although there is a phenomenon that the water flow continuously impacts the packing in the trickling filter, a small amount of free silicone oil component in the packing will gradually escape from the surface of the packing; however, due to the resistance among numerous particles in the packing, especially the packing has a certain adsorption property, the corresponding silicone oil fixing ability is stronger, so a large amount of silicone oil firmly adheres to the inner part of the surface voids of the packing.

[0074] (3) Determination of chlorobenzene concentration in shake flask experiment:

[0075] The modified multiphase filler was obtained according to the method of Example 1. Using a 310 mL sealed bottle as the biological reaction system, blank, modified filler (referring to the intermediate filler of the modified multiphase filler before the section of soaking in silicone oil during the production process), and modified multiphase filler were successively added to 3 sealed bottles. Thus, three experimental groups were formed, which are simply referred to as: blank group, modified group, and multiphase group. A certain amount of inorganic salt medium and 1 mL of activated chlorobenzene highly efficient degrading bacterium Relstoniajolanacearum XCW-1 bacterial solution (screened from the activated sludge of a certain chemical factory in Zhejiang) in the logarithmic growth phase were simultaneously added to the three experimental groups, making the total liquid volume 100 mL. Then, 18 μL of chlorobenzene with a concentration of 200 mg·L -1 (Shanghai Macklin Biochemical brand, available from the market) was added. Then, the sealed bottles were all placed in a shaker at a temperature of 30 °C and a rotation speed of 160 r·min -1 and oscillated for cultivation. 0.8 mL of gas in the bottle was taken every 1 - 7 h. Each experiment was repeated three times.

[0076] The chlorobenzene concentration in the gas phase was quantitatively analyzed using a gas chromatograph (Agilent 6890, USA). The chromatographic column was an HP-Innowax type capillary column (30 m × 0.32 mm × 0.5 μm), with an FID detector. The vaporization chamber and detector temperatures were 200 °C and 180 °C respectively, and the column temperature was 100 °C. Carrier gas: nitrogen; column flow rate: 1 mL·min -1 ; split ratio: 30:1; injection volume: 800 μL. The concentration of the corresponding substrate chlorobenzene in each experimental group was determined according to the calibration curve method. The curve of the chlorobenzene concentration (mg·m -3 ) and the measured peak area was Y = 1.8776X - 573.39, R 2 = 0.9981.

[0077] The change in chlorobenzene concentration in the shake flask experiment is as Figure 3 shown.

[0078] See Figure 3 for the change graph of the degradation rate between the multiphase filler and the ordinary filler. From Figure 3Data analysis and comparison show that: The modified multiphase group has completely degraded chlorobenzene within 18 h, while the modified group and the blank group need to be delayed by 2 - 4 h to achieve the same effect. This indicates that the degradation rate of chlorobenzene in the modified multiphase group is higher than that of other experimental groups. Due to the existence of bound silicone oil inside the modified multiphase group, its solubility for chlorobenzene itself is better, which also contributes to a significant increase in its mass transfer rate. When the chlorobenzene concentration fluctuates greatly, the presence of multiphase fillers can significantly reduce the chlorobenzene concentration in the aqueous phase, broaden the range of substrate inhibition concentration, and prevent the side effects caused by the inhibition of high-concentration substrates on the bacteria in the aqueous phase; at the same time, it can significantly increase the mass transfer driving force of chlorobenzene, thereby accelerating mass transfer. In short, the modified multiphase fillers not only effectively improve the affinity of the reaction system for the target substrate, but also play a positive role in substrate mass transfer and microbial resistance to high-concentration substrate inhibition, ultimately accelerating its degradation rate.

[0079] (4) Determination of carbon dioxide concentration in the shake flask experiment:

[0080] The modified multiphase fillers were obtained according to the preparation method of Example 1. Using a 310 mL sealed bottle as the biological reaction system, the blank, modified, and modified multiphase fillers were successively added to 3 sealed bottles. Thus, three experimental groups were formed, namely: the blank group, the modified group, and the modified multiphase group. A certain amount of inorganic salt medium and 1 mL of XCW-1 bacterial liquid activated to the logarithmic growth phase were simultaneously added to the three experimental groups, making the total liquid volume 100 mL. Then, 18 μL of chlorobenzene with a concentration of 200 mg·L -1 (Shanghai Macklin Biochemical Co., Ltd., available on the market) was added. Then, the sealed bottles were all placed in a shaker at a temperature of 30 °C and a rotation speed of 160 r·min -1 for oscillating culture, and 0.8 mL of gas in the bottle was taken every 1 - 7 h. Each experiment was repeated three times.

[0081] The concentration of CO2 in the gas phase was quantitatively analyzed using a gas chromatograph (Agilent 6890, USA). The chromatographic column was an HP-Plot-Q type capillary column (30 m × 0.32 mm × 20 μm), and the TCD detector was used. The inlet and detector temperatures were 90 °C and 180 °C respectively, and the column temperature was 40 °C. Carrier gas: N2; total flow rate: 107 mL·min -1 ; split ratio: 50:1; gas injection volume: 800 μL. The concentration of generated carbon dioxide was measured using a gas chromatograph according to the calibration curve method. In this detection, the curve of the CO2 concentration (mg·L -1 ) versus the measured peak area was Y = 0.3363X + 0.3397, R 2 = 0.9996.

[0082] The change in the concentration of carbon dioxide generated in the shake flask experiment is as Figure 4 shown. From Figure 4Data analysis and comparison show that: as the reaction time increases, the concentration of generated carbon dioxide gradually increases. After 18.5 h of reaction, the concentration of carbon dioxide generated by the modified multiphase group is significantly higher than that of the other two experimental groups, and the corresponding carbon dioxide increase rate is faster. When the reaction reaches 21.5 h, the concentration of generated carbon dioxide reaches a peak value of 98.1 mg·L -1 , indicating that the modified multiphase group has a better degradation effect on chlorobenzene waste gas. Chlorobenzene waste gas diffuses from the gas phase to the liquid surface, and then from the liquid surface to the interface between the liquid phase and the biofilm. Since the non-aqueous phase in the packing can significantly reduce the concentration of chlorobenzene in the aqueous phase, it broadens the range of substrate inhibition concentration; at the same time, when the gas-liquid is in equilibrium, the uniformity of the escaped chlorobenzene concentration is relatively high and the concentration is relatively low. All these factors are conducive to its degradation by microorganisms in the biofilm into more carbon dioxide and water. In addition, chlorobenzene waste gas is utilized by the microbial cells themselves, and carbon dioxide is discharged through diffusion. Therefore, the concentration of outlet carbon dioxide represents the intensity of microbial metabolism of carbon sources. The higher the concentration of outlet carbon dioxide, the more chlorobenzene waste gas is degraded by microorganisms.

[0083] (5) Determination of the concentration of extracellular protein (PN) of microorganisms in the aqueous phase and on the packing in the shake flask experiment:

[0084] Extract extracellular polymeric substances (EPS) on the biological surface by the hot extraction method. After centrifuging the sample to be measured, discard the supernatant, wash it three times with PBS and resuspend it. After heating in a water bath at 80 °C for 30 min, centrifuge to separate the supernatant (4 °C, 12,000 rpm, 15 min). Filter the supernatant through a 0.45 μm filter membrane and store it at -4 °C for protein determination.

[0085] Determination of extracellular protein concentration: The Bradford method is used to determine the protein content. In the experiment, bovine serum albumin solution is used as the standard solution. Add 0, 0.1, 0.2, 0.3, 0.4, 0.5 mL of 100 mg·L -1 standard solution to the colorimetric tubes respectively, make up to 1 mL with deionized water, add 5 mL of Coomassie Brilliant Blue reagent to the tubes, mix well and incubate at 30 °C for 5 min. After sufficient color development, measure the absorbance at a wavelength of 595 nm with an ultraviolet spectrophotometer. Draw the absorbance - bovine serum albumin solution concentration standard curve. Take 1 mL of EPS sample in a colorimetric tube, perform the above steps, measure the absorbance at a wavelength of 595 nm, and obtain the protein concentration in the EPS sample according to the standard curve. In this detection, the curve of protein concentration (mg·L -1 ) vs. measured absorbance is Y = 0.0106X + 0.0138, R 2 = 0.9954.

[0086] The changes in the protein concentration of microorganisms in the aqueous phase and on the packing in the shake flask experiment are as Figure 5 shown.

[0087] from Figure 5 Comparison of the middle column chart shows that after each group completely degraded chlorobenzene, the protein concentration in the water phase was significantly higher than that in the filler group. This may be because when the bacterial metabolism rate is high, although the filler has a certain adhesion to the bacteria, there are still a large number of bacteria that cannot be fixed. They will escape from the surface of the filler into the water phase, and the volume of the filler accounts for a small proportion of the entire system, which also makes the protein concentration in the water phase greater than the protein concentration on the surface of the filler.

[0088] The protein concentration on the multiphase filler is higher than that in other experimental groups, while the blank group is the lowest. This is because the bound silicone oil in the multiphase group can absorb a large amount of chlorobenzene, which is similar to a "buffer pool" and ultimately plays the role of gas-liquid equilibrium. When the concentration of chlorobenzene is unevenly distributed in the system, it can absorb part of the high-concentration chlorobenzene and compensate for part of the low-concentration chlorobenzene until the chlorobenzene in the system reaches a balanced distribution. Due to the above characteristics of the multiphase filler in the hydrophobic exhaust gas system, the microorganisms in the system can grow stably and efficiently; at the same time, some studies have used the measurement of protein content to characterize the biomass, which also makes the corresponding protein concentration higher than other experimental groups.

[0089] On the other hand, since the modified group belongs to the middle group of the multiphase group, their surfaces have been chemically treated, and their rough surfaces are more suitable for the growth of microorganisms. During the degradation of hydrophobic waste gas, because microorganisms are easy to attach to the rough surface of the modified filler, their metabolism is higher than that of the blank group, which further shows that the multiphase group is superior in the degradation performance of hydrophobic waste gas.

[0090] (6) Determination of dehydrogenase activity (DHA) of microorganisms in the aqueous phase and on the filler in the shake flask experiment:

[0091] After the shake flask experiment of the above test is completed, the mixed solution of the aqueous phase and filler attachments in the shake flasks corresponding to the three experimental groups is used as the test solution. Add 0.3mL of the test solution, 1.5mL of Tris-HCl buffer with a pH of 7.5, and 1mL of INT (iodonitrotetrazolium violet) solution with a concentration of 0.2% to three 10mL centrifuge tubes respectively. Quickly place the prepared samples in a 37°C water bath and shake for 30 minutes, and add 1mL of 37% formaldehyde (analytical grade) to terminate the enzyme reaction. Rotate at 5000r.min -1 Centrifuge at 4000 r.min for 5 min, remove the supernatant after the precipitate and water are separated. Add 5 mL of methanol (analytical grade) respectively, mix and stir evenly, and continue to extract for 10 min in a dark place (shading condition) at 37°C. -1Centrifuge at a rotational speed for another 5 min, and take the supernatant to measure the absorbance at a wavelength of 485 nm. The dehydrogenase activity in the solution is measured according to the calibration curve method. In this detection, the curve of dehydrogenase activity (μmol·ml -1 .h -1 ) vs. the measured absorbance is Y = 0.8601X + 0.018, R 2 = 0.9969.

[0092] The changes in the dehydrogenase activity (DHA) of microorganisms in the aqueous phase and on the packing in the shake flask experiment are as Figure 5 shown.

[0093] From Figure 6 analysis and comparison, it can be seen that after the multiphase group degrades chlorobenzene, the dehydrogenase activity on its packing is significantly higher than that of other experimental groups, while the blank group is the lowest. This is because the bound silicone oil in the multiphase group can dissolve a large amount of chlorobenzene, and it itself is equivalent to a "reservoir", playing a role in gas-liquid balance. When the chlorobenzene concentration is high, it can absorb part of the chlorobenzene, and when its concentration is low, it can release part of the chlorobenzene, ultimately enabling the stable degradation of chlorobenzene at a certain concentration. Since the surfaces of the packings in both the multiphase group and the modified group have been chemically treated, their rough surfaces can provide a large amount of growth space for microorganisms, and thus more microorganisms are more likely to attach and grow on their surfaces; the growth condition of microorganisms on the surface of the modified packing group is higher than that of the blank group, which further indicates that the multiphase group is more superior in terms of waste gas degradation rate and microbial metabolism. In addition, the dehydrogenase activity in the aqueous phase of the three experimental groups is always weaker than that on the packing, which may be because the microorganisms in water are easily washed away by the water flow and have no carrier attachment, and their resistance to environmental impact is insufficient, which also results in a lower overall dehydrogenase activity.

[0094] (7) Determination of the waste gas degradation rate in the trickle bed reactor:

[0095] Simulate the waste gas entering from the bottom of the biotrickling filter (the structure is shown in Figure 10 ) and discharging from the top of the reactor. The inlet concentration of the chlorobenzene waste gas is maintained at 100 mg·m -3Around, control the pH of the inorganic salt nutrient solution to 7.0, the temperature to 30 °C, the spraying volume of the nutrient solution to 5 - 8 L / h, the residence time to 90 s. When it basically reaches stability after running for 25 days, the biofilm formation is completed. The experiments were divided into a blank group (i.e., composed of inorganic salt medium, degradation bacteria seed liquid, blank packing, and chlorobenzene), a modified group (i.e., composed of inorganic salt medium, degradation bacteria seed liquid, modified packing, and chlorobenzene), and a multiphase group (i.e., composed of inorganic salt medium, degradation bacteria seed liquid, modified multiphase packing, and chlorobenzene). Add the modified multiphase packing obtained by the preparation method of Example 1 to the reactor of the multiphase group, and the three groups of reactors are all operating in a steady state. The reactor operates continuously, and 500 mL of nutrient solution is replaced every 3 days. Measure the substrate concentrations at the inlet and outlet and the parameters required for the experiment every day. See the degradation rate change diagrams of the multiphase packing and the ordinary modified packing in Figure 7 。

[0096] From Figure 7 The curve points in it can be seen that the removal rate of the modified group is significantly higher than that of the blank group, and the removal performance of the multiphase group is the best. When the reactor is stable, the average removal rate of the multiphase group is 70.1%, while the average removal rate of the modified group is 60.9%, and the average removal rate of the blank group is 50.8%. This also shows that the strengthening effect of the non-aqueous phase in the multiphase group is obvious.

[0097] The removal effect of the modified group is stronger than that of the blank group. This is because when the inlet concentration of the substrate is relatively low, the content of elements in the packing in the blank group is less, and the surface is relatively smooth, which cannot meet the attachment and normal growth of microorganisms, and even cannot reach its degradation performance. On the contrary, because the surface of the modified packing is relatively rough, there are certain amounts of nutrients such as starch and hydroxyapatite in it, and these chemical substances can well promote the attachment, growth, and accelerated reproduction of microorganisms on the packing surface. Due to the existence of the non-aqueous phase medium in the multiphase group, on the one hand, it can adsorb a part of the waste gas, and on the other hand, it can also accelerate the mass transfer rate of the substrate, which will strengthen the metabolism of microorganisms and ultimately improve the degradation performance of the entire reactor.

[0098] (8) Degradation rate change diagrams of different packing groups during the starvation period:

[0099] The simulated waste gas enters from the bottom of the reactor and exits from the top of the reactor. Before the starvation period, the inlet concentration of the chlorobenzene waste gas is maintained at 100 - 200 mg·m -3 , and after the starvation period, the inlet concentration is maintained at 100 - 300 mg·m -3 ; at the same time, control the pH of the inorganic salt nutrient solution to 7.0, the temperature to 30 °C, the spraying volume of the nutrient solution to 5 - 8 L / h, the residence time to 90 s, and other conditions are the same as Figure 7The same. The experiment was divided into a control group (i.e., composed of inorganic salt medium, degradation bacteria seed liquid, modified filler and chlorobenzene) (here the modified filler is the intermediate filler before the section of soaking silicone oil in the production process of the modified multiphase filler) and a multiphase group (i.e., composed of inorganic salt medium, degradation bacteria seed liquid, modified multiphase filler and chlorobenzene).

[0100] After stopping the introduction of chlorobenzene waste gas for 5 days, the operation conditions of the control group and the multiphase group are as Figure 8 shown. The removal rate of the control group rapidly decreased from 40% to about 15%, while the removal rate of the multiphase group remained basically unchanged and continued to maintain at about 50%. This may be because after stopping the introduction of the substrate (carbon source), the substrate in the control group was exhausted. The degradation bacteria are aerobic bacteria, and their metabolism is inseparable from the carbon source. When oxygen supply is stopped for a short time, the bacteria will have endogenous respiration, and the activity of the bacteria will also decrease significantly, ultimately leading to a significant decrease in the removal effect.

[0101] When the substrate stops being introduced into the reaction device, due to the large amount of chlorobenzene adsorbed in the non-aqueous phase of the multiphase group before, at this time, due to the sharp decrease in the concentration of the external system, under the action of gas-liquid equilibrium, a large amount of chlorobenzene in the non-aqueous phase will escape. At this time, the bacteria will make full use of the carbon source to maintain the normal metabolism of the microorganisms and keep the degradation performance of the whole reaction system stable.

[0102] (9) Instantaneous change diagram of the degradation rate of different filler groups under high load:

[0103] The simulated waste gas enters from the bottom of the reactor and exits from the top of the reactor. At low load, the inlet concentration of chlorobenzene waste gas is maintained at 600 - 700 mg·m -3 , and at high load, the inlet concentration is maintained at 1300 - 1400 mg·m -3 ; at the same time, the pH of the inorganic salt nutrient solution is controlled at 7.0, the temperature is 30°C, the spraying amount of the nutrient solution is 5 - 8 L·h -1 , the residence time is 30 s, and other conditions are the same as Figure 7 the same. The experiment was divided into a control group (i.e., composed of inorganic salt medium, degradation bacteria seed liquid, modified filler and chlorobenzene) and a multiphase group (i.e., composed of inorganic salt medium, degradation bacteria seed liquid, modified multiphase filler and chlorobenzene).

[0104] After increasing the concentration of chlorobenzene waste gas, the operation conditions of the control group and the multiphase group are as Figure 9 shown. The removal rate of the control group rapidly decreased from 52% to about 35%, and the removal rate of the multiphase group slowly decreased from 63% to about 59%; after operating for 24 hours, the initial concentration of chlorobenzene was restored to 600 - 700 mg·m -3 .

[0105] The removal rate of the control group decreased and could only recover to about 42%, while the removal rate of the multiphase group remained basically unchanged. This may be because after the chlorobenzene concentration was increased to the high-load condition, the microorganisms in the control group were poisoned, and their degradation performance decreased significantly. Even after the chlorobenzene concentration returned to the initial concentration, their removal performance could not reach the previous degradation effect.

[0106] For the multiphase group in the short term, since the non-aqueous phase therein can serve as a buffer for substances such as substrates and oxygen, it absorbs a large amount of chlorobenzene waste gas under high-load conditions, reducing the degradation pressure of the entire system. At this time, the bacterial cells will not be negatively affected by high-concentration chlorobenzene. It can make full use of the carbon source, maintain the normal metabolism of microorganisms, keep the degradation performance of the entire reaction system stable, and ensure the stable and efficient operation of the biochemical reaction.

[0107] The above are the preferred embodiments of the present invention and do not limit the present invention in any way. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention, as long as they are within the spirit defined by the claims, also belong to the protection scope of the present invention.

Claims

1. A modified multiphase filler is obtained by the following method: (1) Mix a polyurethane prepolymer with carbon powder and starch to form a prefabricated mixture; (2) Screen, melt and granulate the prefabricated mixture to obtain uniformly mixed particles; (3) Secondarily mix, plasticize, injection mold, foam and shape the generated particulate matter to obtain a polyurethane foam; (4) Place the polyurethane foam in alcohol solution, acid solution and alkali solution in sequence for impurity removal, and then dry it; (5) Immerse the dried polyurethane foam in a ferric chloride solution with a mass concentration of 15 - 45% for 10 - 18 h to allow the voids therein to adsorb and fill the iron salt solution; (6) Keep it at a high temperature of 100 - 200 °C for oxygen - isolated thermal treatment for 20 - 60 min, and then cool it to room temperature; (7) Immerse the cooled polyurethane foam in silicone oil for 20 - 100 h, and air - dry it at 30 - 40 °C for 12 - 18 h to obtain the said modified multiphase filler.

2. The modified multiphase filler according to claim 1, wherein, The mass ratio of the polyurethane prepolymer, carbon powder, and starch is 1: 0.05-1.0: 0.01-2.

0.

3. The modified multiphase filler according to claim 1, characterized in that In step (2), the prefabricated mixture is put into a melting mixer for melting and granulation. The melting and pressure-holding time is fixed at 0.5-15 s, the cooling time is 0.2-5.0 s, the pressure is 5-10 MPa, and the ambient temperature is maintained at 50-100 °C. Then, the generated particles are transferred to a screw machine for plasticization at 80-150 °C, and then injected into a mold and heated to 140-210 °C for foaming for 5-30 min. Finally, heat treatment is carried out at 40-80 °C for shaping to obtain the polyurethane foam.

4. The modified multiphase filler according to claim 1, characterized in that In step (4), the alcohol solution is an ethanol solution with a volume concentration of 30% to 75%, and the soaking time is 5-30 min.

5. The modified multiphase filler according to claim 1, characterized in that In step (4), the acid solution is a nitric acid, sulfuric acid, or hydrochloric acid solution with a mass concentration of 5% to 25%.

6. The modified multiphase filler according to claim 1, characterized in that In step (4), the alkali solution is a sodium hydroxide solution, potassium hydroxide solution, or sodium carbonate solution with a mass concentration of 10% to 30%.

7. Application of the modified multiphase filler according to claim 1 in removing hydrophobic organic pollutants.

8. The application according to claim 7, characterized in that The hydrophobic organic pollutant is chlorobenzene.

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