CN110642322A - Method for treating uranium-containing wastewater by utilizing electrogenesis microorganism-loaded Fe/C nanocomposite - Google Patents

Method for treating uranium-containing wastewater by utilizing electrogenesis microorganism-loaded Fe/C nanocomposite Download PDF

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CN110642322A
CN110642322A CN201810669073.8A CN201810669073A CN110642322A CN 110642322 A CN110642322 A CN 110642322A CN 201810669073 A CN201810669073 A CN 201810669073A CN 110642322 A CN110642322 A CN 110642322A
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uranium
nzvi
loaded
cnt
nano
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聂小琴
项书宏
董发勤
丁聪聪
程文财
刘明学
何辉超
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Southwest University of Science and Technology
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/30—Treatment of water, waste water, or sewage by irradiation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/70—Treatment of water, waste water, or sewage by reduction
    • C02F1/705—Reduction by metals
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/34—Biological treatment of water, waste water, or sewage characterised by the microorganisms used
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/006—Radioactive compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00—Use of specific compounds during water treatment
    • C02F2305/10—Photocatalysts

Abstract

The invention provides a method for reducing and adsorbing uranium in wastewater under the illumination condition by combining a nano synthetic material with an autonomously electricity-producing microorganism. The method takes nano zero-valent iron (nZVI), a high-conductivity nano carbon material (C) and electrogenesis microorganisms as raw materials, and utilizes the high reduction activity of the nZVI, the photocatalytic effect after the oxidation product of the nZVI is combined with the C and the characteristic that the electrogenesis microorganisms generate bioelectronics to efficiently reduce and adsorb the uranium-containing wastewater. The method comprises the following specific steps: (1) synthesis of nanomaterials (nZVI-CNTs); (2) loading nZVI-CNTs on the surface of a microorganism (bio-nZVI-CNTs); (3) placing the bio-nZVI-CNT in uranium-containing wastewater under illumination, adjusting the pH value to 4-6, and stirring and mixing uniformly, wherein the concentration of the bio-nZVI-CNT is less than or equal to 50 mg/L; (4) after 2 hours, the solid and the liquid are separated; (5) the uranium is recovered by desorption and the bio-nZVI-CNT is reused. The method can reduce the uranium content in the uranium-bearing wastewater of which the uranium content is less than or equal to 50mg/L by over 96 percent, and the adsorption capacity is up to 436.4 mg/g. Simple operation, high removal efficiency, short time, and good environmental, social and economic benefits.

Description

Method for treating uranium-containing wastewater by utilizing electrogenesis microorganism-loaded Fe/C nanocomposite
Technical Field
The invention relates to the field of uranium-containing radioactive wastewater treatment, and relates to a complete set of technology for rapidly removing hexavalent uranyl in uranium wastewater by comprehensively utilizing bioelectronics of electrogenic microorganisms, high reaction activity of nano materials and photocatalytic characteristics of oxides.
Background
Uranium is the most main nuclear fuel in the utilization of nuclear energy at present, along with the rapid development of nuclear energy, the increase of uranium resource demand, the scale of uranium ore exploitation and smelting enlarges, must produce more low concentration uranium pollution waste water, and the kind is also more and more, and is growing to the potential threat of human health and natural ecological environment, and people also put forward higher requirement to the processing of radioactive waste water. In the aspect of treatment of radioactive wastewater, particularly uranium-containing wastewater, methods such as chemical precipitation, ion exchange, membrane separation, redox, evaporation concentration, adsorption, membrane treatment and the like are mainly used at present. However, these conventional methods have various disadvantages in the actual operation process, such as long treatment period, low removal efficiency, high cost, large amount of secondary waste, and the like.
Uranium is usually hexavalent uranyl ion UO in water2 2+The form exists, when hexavalent uranyl is reduced to quadrivalence, flocculent precipitate can be formed and can be removed by standing or filtering, so that the hexavalent uranyl can be quickly reduced and separated from the solution by using more active and easily prepared metal, and the removal efficiency is high.
According to related research reports [ Ding, C, et al, Effects of Bacillus subtilis on the reduction of U (VI) by nano-Fe0, Geochimica et cosmochimia Acta, 2015.165: 86-107 ], nano zero-valent iron has high activity and can rapidly reduce hexavalent uranyl, but because the nano zero-valent iron is too active and easy to aggregate, the simple nano zero-valent iron is blocked by an oxidation film formed by rapid oxidation of the surface of an aggregate in the process of removing uranyl, so that the reduction rate of the nano zero-valent iron on uranyl in unit mass is not high. Meanwhile, according to the literature reports [ Jiang L C., et al., Charge transfer properties and phosphor electrochemical activity of Ti02/MWCNT hybrid, electric, Acta, 2010.4(56): p.06-11 ], the combination of the nanoscale iron oxide and certain conductor materials can reduce the energy barrier between a conduction band and a valence band in the iron oxide, reduce the probability of electron hole pair recombination, thereby showing photocatalytic activity and improving the utilization rate of transferable electrons in the environment. Therefore, the patent selects the nano carbon material as a conductor, synthesizes a material (Fe/C material) of the carbon conductor loaded with the nano zero-valent iron, and comprehensively utilizes the combination material (Fe Oxide/C material) of the nano iron Oxide and the carbon conductor formed after the nano zero-valent iron is oxidized. In addition, Shewanella and other electrogenic microorganisms can transmit electrons to the outside through metabolism for external use. Therefore, this patent plans the adsorption site that provides through the electrogenesis microorganism surface group, adsorbs the photocatalysis material in a large number on the thallus surface to improve the synthetic nano-material who adsorbs on the surface through the electron that the thallus provided and to the reduction clearance of uranium.
Aiming at the advantages of the biological-nano material, the composite nano zero-valent iron and nano carbon material are adsorbed on the surface of the electrogenic thallus to be used for reducing and removing hexavalent uranyl in the solution, so that the utilization rate of several materials can be improved, the volume of the combined materials can be increased, solid-liquid separation is easy, and the energy consumption required by separation is reduced.
Disclosure of Invention
In view of the above situation, the invention aims to provide a method for treating uranium-containing wastewater by utilizing electrogenic microorganisms and synthetic nano materials under illumination, which has the characteristics of convenient material acquisition, high removal efficiency, simple treatment steps, environmental friendliness, reusability and the like.
In order to overcome the defects of agglomeration, oxidation and the like of nano zero-valent iron in the using process and fully exert the photocatalytic activity of Fe oxide/C materials, a certain amount of iron ions are reduced to the surface of a carbon nano material such as a multi-wall carbon nano tube and the like to form a synthetic material with high reduction efficiency, the high reducibility of the synthetic material and the photocatalytic property of an oxidation product are utilized, an electrogenic microorganism is combined to provide bioelectronic electrons, hexavalent uranyl in a solution is removed, the uranium concentration in uranium-containing waste water with the concentration less than or equal to 50mg/L can be reduced by more than 96 percent, the adsorption capacity is up to 436.4mg/g, and the purposes of volume reduction, purification and uranium resource recovery of the uranium-containing radioactive waste liquid can be achieved.
The concrete measures are as follows: a method for treating uranium-containing wastewater by using an electrogenesis microorganism-loaded Fe/C nano composite material comprises the following steps of synthesizing a simple nZVI-CNT material, uniformly mixing the material with shewanella electrogenesis microorganisms (bio-nZVI-CNT), placing the mixture into the uranium-containing wastewater, stirring the mixture, carrying out redox reaction on the mixture to rapidly reduce hexavalent uranyl into quadrivalence, combining the quadrivalence with the material to form precipitate, and separating and collecting the precipitate, wherein the specific treatment steps are as follows:
according to the weight ratio of iron: the mass ratio of carbon is 2.5-4: 1, weighing a certain amount of ferrous salt and nano carbon material particles, and placing the weighed ferrous salt and nano carbon material particles in a water solution with a certain volume for heating;
preparing sodium borohydride particles into a solution with the concentration of about 7.5 g/L;
placing the solution in the step (1) in a stirring device at a constant temperature for rapid stirring, and then dropwise adding the sodium borohydride solution in the step (2) until iron ions in the solution are completely reduced to the surface of the nano carbon material (synthesizing a nano Fe/C material);
centrifuging the material obtained in (3) in the absence of oxygen and washing three times with deoxygenated water, then mixing the following materials according to the ratio of Fe/C: the mass ratio of the electricity generating microorganisms is 0.2-0.5: 1, mixing the Fe/C nano composite material with electrogenesis microorganisms in oxygen-free water, and loading the mixture on the surface of thalli to form the electrogenesis microorganism-loaded Fe/C nano composite material;
controlling the pH value of the uranium-containing wastewater to be between 4 and 6, and adding a certain amount of the microorganism-containing Fe/C-loaded nano composite material into each liter of uranium-containing wastewater according to a certain proportion;
reacting the system (5) for about 2 hours under the illumination condition of incandescent lamps with the illumination intensity of about 200W, and performing solid-liquid separation by membrane pressure filtration or standing for a period of time;
and collecting the uranium-containing precipitate, recovering uranium through desorption, and reusing the electricity-generating microorganism-loaded nano composite material.
In order to achieve better removal effect, the following measures can be taken:
iron: the carbon mass ratio is 3, the utilization rate is higher, and the utilization rate is highest when the carbon nano-tube is selected as the carbon nano-material to form the carbon nano-tube composite zero-valent iron (nZVI-CNT).
The mixed solution of the ferrous salt and the nano carbon material has good effect when the temperature is kept between 70 and 90 ℃, and the optimal temperature is 80 ℃.
When the ratio of iron: when the carbon mass ratio is 3:1, about 17mL of 7.5mg/L sodium borohydride solution is needed for preparing 1g of the nano composite material. The synthesis reaction equation of the nano zero-valent iron is as follows: fe2+ + 2BH4- + 6H2O = Fe + 2b (oh)3 +7H 2.
The Shewanella is selected as an electrogenesis microbial material to load nZVI-CNT to form Shewanella loaded nZVI-CNT (bio-nZVI-CNT material), and the nZVI-CNT: the shewanella mass ratio is 3: 8. in order to achieve a better removal effect, the electricity generating microorganisms more suitable for the actual environment can be selected according to the actual situation.
The Shewanella putrefaciens organic liquid medium mainly comprises 15 g of tryptone and 5 g of soytone and 5 g of sodium chloride per liter, and the pH is controlled to be 7.3-7.5.
When the uranium concentration is 50mg/L, the effect of adding 0.11g of bio-nZVI-CNT is the best, and in order to achieve better removal effect, the adding amount of materials can be properly increased or decreased under different uranium concentration wastewater conditions so as to improve the material utilization efficiency and economic benefit.
The synthesized bio-nZVI-CNT material solution system is controlled below 1 mg/L to reduce the volume of the mixed solution.
The deoxidized water can be obtained by heating deionized water to boiling, sealing and cooling.
The environmental temperature is preferably controlled at 20-30 ℃ to ensure that the Shewanella has higher activity.
In order to achieve a better removal effect, the light intensity can be properly increased, and the light wavelength can be adjusted to enhance the photocatalytic effect, but the light is ensured not to damage microorganisms.
The nano material nZVI-CNT is preferably prepared as it is or can be stored under the condition of low temp. and no oxygen.
The uranium-bearing waste water after reduction should be separated as early as possible.
The invention synthesizes a material with high reduction efficiency and high repeated utilization rate by comprehensively utilizing the high reduction activity of nano zero-valent iron, the electrogenesis characteristic of Shewanella and the photocatalytic activity displayed after the combination of iron oxide and carbon nanotubes, and the material is used for reducing and recycling uranium in uranium-containing wastewater, and compared with the prior art, the invention has the following beneficial effects:
(1) the operation is simple, the material can be stored in a certain way after being synthesized, and can be taken and used at any time when needed.
(2) The removing effect is strong, more than 96% of uranium in 1L of uranium solution with 50mg/L can be removed only by 0.11g of synthetic material, and the adsorption capacity reaches 436.4 mg/g.
(3) The reaction time is short, the reaction only needs 2 hours, the treatment time is effectively reduced, and the process treatment efficiency is improved.
(4) The method has the advantages of wide and safe material sources, environmental friendliness and no secondary pollution, and is suitable for uranium-containing radioactive wastewater treatment and uranium resource recovery generated in nuclear fuel circulation.
The reaction mechanism is presumed to be explained as follows:
firstly, reducing hexavalent uranyl into quadrivalence by nano zero-valent iron and precipitating, and converting the nano zero-valent iron into nano iron oxide;
the nanometer iron oxide can generate a large amount of photoelectrons and cavities under the illumination condition, the combination with the carbon nano-tube leads the photoelectrons to be quickly conducted by the carbon nano-tube to hexavalent uranyl adsorbed on the surface of the material for uranium reduction, and the cavities are compounded with biological electrons on the surface of the electrogenic microorganism;
and (3) the iron oxide which receives the bioelectronic electrons shows a photocatalytic effect again under the illumination condition, and the process (2) is repeated, so that the uranium removing effect under the illumination condition is obviously improved.
To further demonstrate the reductive removal mechanism of the synthetic materials, the synthetic materials and the reacted precipitate were characterized as follows:
as can be seen from the electron microscope scanning and the energy spectrum analysis (fig. 6), the same synthesis method was used to synthesize nanoscale zero-valent iron with three different carbon materials [ a: graphene (RGO); b: carbon Nanotubes (CNTs); c: c60] exhibited a different morphology after binding a 2: fe/graphene (nZVI-RGO); b2: fe/carbon nanotubes (nZVI-CNT); c2: Fe/C60(nZVI-C60), in which the zero-valent iron after synthesis is all in the nanometer size. In addition, the form (nZVI-CNT) combined with the carbon nanotube shows that the nano zero-valent iron with smaller size is more uniform and larger in contact surface with the carbon material compared with other two synthetic materials. Therefore, the combination with the carbon nano-tube can more fully exert the photocatalytic activity of the iron oxide.
Electron microscopy and energy spectrum analysis (FIG. 7) showed that the nano-synthetic material completely covered the surface of the cells after loading the nZVI-CNT material with Shewanella (A). The results of the action (B) of the loaded material with uranium solution show that: the nZVI-CNT is changed in morphology after the reaction, and EDS (C) results show that the surface contains more uranium after the reaction. The synergistic removal of hexavalent uranyl is demonstrated using a combination of three materials.
The Fourier transform infrared test result (figure 8) shows that the uranyl peak appears after the reaction, and in addition, the characteristic peak of FeOOH and the characteristic peaks of some other iron oxides appear in the figure after the reaction, which proves that the nano zero-valent iron is converted into an oxidation product due to oxidation after the reaction.
Scanning iron and uranium elements in the nZVI-CNT material before and after reaction by utilizing X-ray photoelectron spectroscopy (figure 9), finding that the content of zero-valent iron is reduced after the reaction, and tetravalent uranium elements exist after the reaction, and proving that the reduction effect of nano zero-valent iron in the nZVI-CNT is embodied in the uranium removal process.
Drawings
And (3) abstract: schematic diagram of synthesis and reaction mechanism
FIG. 1 is a time-efficiency comparison of the same uranium content 50mg/L, pH =5, T =20 ℃, light 200W and dark water under different carbon materials, nano zero-valent iron and different synthetic materials
FIG. 2 comparison of the efficiency of the same uranium-containing 50mg/L, pH =5, T =20 ℃, light 200W and dark water, nZVI-CNT, Shewanella, and loaded bio-nZVI-CNT material
FIG. 3 shows the time-efficiency effect of different ion intensities on bio-nZVI-CNT in water with uranium content 50mg/L, pH =5, T =20 ℃ and illumination of 200W and comparison graph (B) with nZVI-CNT under different ion intensity conditions and temperature on the time-efficiency effect of bio-nZVI-CNT
FIG. 450 mg/L, pH =5, T =20 ℃, and the recycling efficiency of bio-nZVI-CNT on uranium removal in 200W water (A), the leaching rate of Fe in the cycle (B)
FIG. 5 shows the comparison of efficiency (A) in 200W water at 50mg/L, T =20 ℃ under different pH conditions, pH change before and after reaction (B), simulation of U (VI) species state (C) under different pH conditions, and Fe leaching rate (D) under different pH conditions
FIG. 6 scanning electron microscope results before and after binding of three different carbon materials with nanoscale zero-valent iron, RGO (A1), CNT (B1), C60(C1), nZVI-RGO (A2), nZVI-CNT (B2), nZVI-C60(C2)
FIG. 7 scanning Electron microscopy results of bio-nZVI-CNT before (A) and after (B) reaction with uranium and EDS results after reaction
FIG. 8 shows FTIR results before and after reaction of nZVI-CNT with uranyl, raw spectrum (A), second derivative spectrum (B)
FIG. 9 shows the results of elemental X-ray photoelectron spectroscopy before and after reaction of nZVI-CNT with uranyl, in which upper and lower spectra in the A and C plots respectively show the Fe2p orbital scan and the full-spectrum scan before and after the reaction, and B shows the U4f orbital scan after the reaction;
FIG. 10 is a schematic diagram of synthesis and reaction mechanism.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments.
Example 1:
0.01 g of carbon material, 0.03 g of nano zero-valent iron and 0.04 g of synthetic material are respectively put into fourteen groups of water containing 1L of uranium with the uranium content of 50mg/L under the conditions of pH =5, T =20 ℃, illumination of 200W and darkness, and the time-dependent change relationship of uranium removal efficiency is shown in figure 1. It was found by comparison that the removal rate R of the synthetic material under Light conditions showed very high improvement compared to the individual materials [ e.g. R (96.87%, nZVI-CNT, Light, 0.04 g) > R (81.16%, nZVI-CNT, Dark, 0.04 g) > R (41.45%, nZVI, Dark, 0.03 g) + R (2.86%, CNT, Dark, 0.01 g) ], and that the advantages of nZVI-CNT in the three synthetic materials are more pronounced [ R (96.87%, nZVI-CNT, Light, 4 mg) > R (70.41%, nZVI-RGO, Light, 4 mg) > R (54.81%, nZVI-C60, Light, 3 mg) ], so that the use of a bonding material of carbon nanotubes with nanoscale zero-valent iron is more suitable.
Example 2:
0.03 g of nZVI-CNT, 0.08g of Shewanella and 0.11g of bio-nZVI-CNT material are respectively put into six groups of 1L of uranium water with the uranium content of 50mg/L under the conditions of pH =5, T =20 ℃, illumination of 200W and darkness. The uranium removal efficiency is shown in figure 2 as a function of time. Through comparison, the effect of the single material [ R (97.11%, bio-nZVI-CNT, Light, 0.11 g) > R (64.40%, bio-nZVI-CNT, Dark, 0.11 g) > R (36.56%, nZVI-CNT, Dark, 0.03 g) + R (22.24%, S. Putrefiens, Dark, 0.08 g) ] can be further improved by combining the synthetic material nZVI-CNT with Shewanella under the illumination condition, so that the composite material has a synergistic effect with Shewanella.
Example 3:
sodium chloride particles were put into six groups of water containing 1L of uranium of 50mg/L at pH =5, T =20 ℃ and 200W of light, respectively, so that the concentrations became 0.01 mol/L, 0.05 mol/L and 0.1 mol/L, and then 0.03nZVI-CNT and 0.11g of bio-nZVI-CNT material were put into the water. The uranium removal efficiency as a function of time and the ionic strength are shown in fig. 3A and B. The ion intensity is higher, the effect on the bio-nZVI-CNT is larger (the uranium removal rate is reduced along with the increase of the ion intensity), however, the ion intensity has little influence on the removal efficiency of the nZVI-CNT, and the reduction of the ion intensity is proper, so that the removal efficiency of the bio-nZVI-CNT material can be improved.
Example 4:
respectively adding 0.11g of bio-nZVI-CNT material into three groups of water bodies containing 1L of uranium with the uranium content of 50mg/L at different temperatures under the conditions of pH =5 and illumination of 200W. The results of the uranium removal efficiency as a function of time are shown in fig. 3C. By comparison, it was found that a suitable increase in temperature increases the rate of uranium removal (equilibration times are reduced from 60 min to 20 min), but that the overall uranium removal is slightly reduced (excessive temperatures negatively affect the shewanella metabolism).
Example 5:
and under the conditions of pH =5, T =20 ℃ and illumination of 200W, sequentially adding 22 mg of bio-nZVI-CNT into a group of 100 mL of uranium water with a uranium content of 50mg/L for reaction for two hours, then carrying out centrifugal separation, desorbing the separated precipitate for three times by using 1 mol/L sodium carbonate solution, then cleaning the precipitate by using deoxygenated water, adding the precipitate into a second group of 100 mL uranium water with a uranium content of 50mg/L, and sequentially repeating the steps for four times, so as to measure the uranium removal efficiency and the Fe leaching rate in different circulation times, wherein the result is shown in figure 4. The results show that the synthetic material still has high removal rate (95.84%, 87.43%, 67.85%, 18.18%) after multiple cycles, and the low leaching rate of Fe (8.85%, 5.49%, 1.74%) shows that the material has high stability. Therefore, the material has higher stability, can be recycled and reused, and reduces the resource consumption.
Example 6:
and (3) respectively putting 0.11g of bio-nZVI-CNT material into eight groups of water bodies containing 1L of uranium with uranium content of 50mg/L at different pH values under the conditions of T =20 ℃ and illumination of 200W, wherein the results of the removal efficiency of the uranium along with the change of the pH value are shown in the attached figure 5A after reaction for two hours, the pH change values before and after the reaction are shown in the attached figure 5B, the uranium species state simulation under different pH conditions is shown in the attached figure 5C, and the Fe leaching rate under different pH conditions is shown in the attached figure 5D. The results show that the material shows different stability under different pH conditions, the higher the acidity, the higher the Fe leaching rate, and the pH influences the uranium species state and thus the uranium removal rate (the higher the pH, the more difficult the form of hexavalent uranyl is to be reduced). Meanwhile, the bio-nZVI-CNT material has the highest uranium reduction removal rate between pH4 and 6 and is relatively more stable.
Example 7:
scanning electron microscope tests are carried out before and after three different carbon materials are combined with the nano zero-valent iron, and the results are shown in figure 6 [ RGO (A1), CNT (B1), C60(C1), nZVI-RGO (A2), nZVI-CNT (B2), nZVI-C60(C2) ] electron microscope scanning and energy spectrum analysis. In addition, the form (nZVI-CNT) combined with the carbon nano-tube shows that the size of the nano zero-valent iron is smaller, and the contact surface with the carbon material is more uniform and larger compared with other two synthetic materials. Therefore, the combination with the carbon nano-tube can more fully exert the photocatalytic activity of the iron oxide.
Example 8:
the bio-nZVI-CNT before and after the reaction with the uranium solution is taken for scanning electron microscope test, and the result is shown in the attached figure 7. Scanning electron microscope results show that after shewanella is used for loading the nZVI-CNT material (A), the carbon nano-tubes cover the surfaces of the bacteria, the loaded material and a uranium solution act (B) to show that the nZVI-CNT is changed after the loaded material and the uranium solution act, EDS (C) results show that the surface of the bio-nZVI-CNT contains more uranium, and the main component of the synthetic material after the reaction contains C, U, Fe elements.
Example 9:
the results of Fourier transform infrared spectroscopy tests on nZVI-CNT before and after reaction with uranium solution are shown in figure 8. The results show that the synthesized material after the reaction shows an absorption peak of uranium and a characteristic absorption peak of iron oxide, which indicates that the synthesized material can indeed remove uranium, and nano zero-valent iron in the synthesized material is converted into iron oxide after the reaction.
Example 10:
the nZVI-CNT before and after the reaction with the uranium solution is taken to carry out X-ray photoelectron spectroscopy test, and the result is shown in figure 9. The scanning of the elements of iron (A) and uranium (B) shows that the content of zero-valent iron after reaction is reduced, and hexavalent and tetravalent appear in uranium scanning results of precipitates, so that the conjecture that the nano zero-valent iron reduces uranyl and converts the uranyl into oxide is reasonable, and meanwhile, in combination with example 1, the removal rate under the illumination condition is obviously increased, which shows that the photocatalysis effect is existed.

Claims (15)

1. A method for treating uranium-containing wastewater by utilizing electrogenesis microorganism-loaded Fe/C nano composite material is characterized by comprising the following steps: synthesize a new nano-material through simple operation, combine and use nano-material and electrogenesis microorganism to be used for getting rid of uranium-bearing waste water, the concrete step is:
according to the weight ratio of iron: the mass ratio of carbon is 2.5-4: 1, weighing a certain amount of ferrous salt and nano carbon material particles, and placing the weighed ferrous salt and nano carbon material particles in a water solution with a certain volume for heating;
preparing sodium borohydride particles into a solution with the concentration of about 7.5 g/L;
placing the solution in the step (1) in a stirring device at a constant temperature for rapid stirring, and then dropwise adding the sodium borohydride solution in the step (2) until iron ions in the solution are completely reduced to the surface of the nano carbon material (synthesizing a nano Fe/C material);
centrifuging the material obtained in (3) in the absence of oxygen and washing three times with deoxygenated water, then mixing the following materials according to the ratio of Fe/C: the mass ratio of the electricity generating microorganisms is 0.2-0.5: 1, mixing the Fe/C nano composite material with electrogenesis microorganisms in oxygen-free water, and loading the mixture on the surface of thalli to form the electrogenesis microorganism-loaded Fe/C nano composite material;
controlling the pH value of the uranium-containing wastewater to be between 4 and 6, and adding a certain amount of the microorganism-containing Fe/C-loaded nano composite material into each liter of uranium-containing wastewater according to a certain proportion;
reacting the system (5) for about 2 hours under the illumination condition of incandescent lamps with the illumination intensity of about 200W, and performing solid-liquid separation by membrane pressure filtration or standing for a period of time;
and collecting the uranium-containing precipitate, recovering uranium through desorption, and reusing the electricity-generating microorganism-loaded nano composite material.
2. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: iron: the mass ratio of carbon is 3: the carbon nanotube composite nano zero-valent iron (nZVI-CNT) has higher utilization rate when 1, and the carbon nanotube is selected as the carbon nanotube material to form the carbon nanotube composite nano zero-valent iron (nZVI-CNT).
3. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material under the illumination condition as claimed in claim 1, wherein the method comprises the following steps: the mixed solution of the ferrous salt and the nano carbon material has good effect when the temperature is kept between 70 and 90 ℃, and the optimal temperature is 80 ℃.
4. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material under the illumination condition as claimed in claim 1, wherein the method comprises the following steps: when the ratio of iron: when the carbon mass ratio is 3, about 17mL of 7.5mg/L sodium borohydride solution is needed to prepare 1g of the nano composite material.
5. The synthesis reaction equation of the nano zero-valent iron is as follows: fe2++ 2BH4 - + 6H2O = Fe + 2B(OH)3 + 7H2。
6. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: the Shewanella is selected as an electrogenesis microbial material to load nZVI-CNT to form Shewanella loaded nZVI-CNT (bio-nZVI-CNT material), and the nZVI-CNT: the shewanella mass ratio is 3: 8.
7. in order to achieve a better removal effect, the electricity generating microorganisms more suitable for the actual environment can be selected according to the actual situation.
8. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: the Shewanella organic liquid culture medium mainly comprises 15 g of tryptone, 5 g of soytone and 5 g of sodium chloride per liter, and the pH is controlled to be 7.3-7.5.
9. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: when the uranium concentration is 50mg/L, the effect of adding 0.11g of bio-nZVI-CNT is the best, and in order to achieve better removal effect, the adding amount of materials can be properly increased or decreased under different uranium concentration wastewater conditions so as to improve the material utilization efficiency and economic benefit.
10. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: in order to achieve better removal effect, the synthesized bio-nZVI-CNT material solution system is controlled below 1 mg/L to reduce the volume of the mixed solution.
11. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: the deoxidized water can be obtained by heating deionized water to boiling, sealing and cooling.
12. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: in order to achieve better removal effect, the environmental temperature is preferably controlled to be 20-30 ℃ so as to ensure that the Shewanella has higher activity.
13. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: in order to achieve a better removal effect, the light intensity can be properly increased, and the light wavelength can be adjusted to enhance the photocatalytic effect, but the light is ensured not to damage microorganisms.
14. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: in order to achieve better removal effect, the nano material nZVI-CNT is preferably prepared as it is, and can also be stored under the condition of low temperature and no oxygen.
15. The method for treating uranium-bearing wastewater by using the electrogenic microorganism-loaded Fe/C nanocomposite material according to claim 1, wherein the method comprises the following steps: in order to achieve a better removal effect, the uranium-containing wastewater after reduction should be subjected to solid-liquid separation as soon as possible.
CN201810669073.8A 2018-06-26 2018-06-26 Method for treating uranium-containing wastewater by utilizing electrogenesis microorganism-loaded Fe/C nanocomposite Pending CN110642322A (en)

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CN111672469A (en) * 2020-06-17 2020-09-18 西南科技大学 Fe-Ti bimetallic nanoparticle-loaded honey carbon material and preparation method and application thereof
CN112080638A (en) * 2020-07-23 2020-12-15 衡阳师范学院 Method for recovering uranium from uranium-containing wastewater
CN113104921A (en) * 2021-03-31 2021-07-13 核工业北京化工冶金研究院 Method for treating uranium-containing wastewater
CN113702572A (en) * 2020-11-05 2021-11-26 核工业北京化工冶金研究院 Experimental method for treating uranium-bearing mine water by using iron-carrying charcoal

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111672469A (en) * 2020-06-17 2020-09-18 西南科技大学 Fe-Ti bimetallic nanoparticle-loaded honey carbon material and preparation method and application thereof
CN112080638A (en) * 2020-07-23 2020-12-15 衡阳师范学院 Method for recovering uranium from uranium-containing wastewater
CN113702572A (en) * 2020-11-05 2021-11-26 核工业北京化工冶金研究院 Experimental method for treating uranium-bearing mine water by using iron-carrying charcoal
CN113104921A (en) * 2021-03-31 2021-07-13 核工业北京化工冶金研究院 Method for treating uranium-containing wastewater
CN113104921B (en) * 2021-03-31 2021-12-07 核工业北京化工冶金研究院 Method for treating uranium-containing wastewater

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