CN113664214B - Nanometer zero-valent iron filler, preparation method thereof and application thereof in denitrification - Google Patents
Nanometer zero-valent iron filler, preparation method thereof and application thereof in denitrification Download PDFInfo
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- CN113664214B CN113664214B CN202110900132.XA CN202110900132A CN113664214B CN 113664214 B CN113664214 B CN 113664214B CN 202110900132 A CN202110900132 A CN 202110900132A CN 113664214 B CN113664214 B CN 113664214B
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- 239000000945 filler Substances 0.000 title claims abstract description 114
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 108
- 238000002360 preparation method Methods 0.000 title abstract description 16
- 239000004698 Polyethylene Substances 0.000 claims abstract description 41
- -1 polyethylene Polymers 0.000 claims abstract description 41
- 229920000573 polyethylene Polymers 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 30
- 241001122767 Theaceae Species 0.000 claims abstract description 29
- 150000008442 polyphenolic compounds Chemical class 0.000 claims abstract description 25
- 235000013824 polyphenols Nutrition 0.000 claims abstract description 20
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 18
- 238000002791 soaking Methods 0.000 claims abstract description 17
- 238000001035 drying Methods 0.000 claims abstract description 11
- 239000011790 ferrous sulphate Substances 0.000 claims abstract description 9
- 235000003891 ferrous sulphate Nutrition 0.000 claims abstract description 9
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract description 9
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000008367 deionised water Substances 0.000 claims abstract description 8
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 8
- 238000005406 washing Methods 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims abstract description 5
- 230000007935 neutral effect Effects 0.000 claims abstract description 4
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 10
- 229910001448 ferrous ion Inorganic materials 0.000 claims description 10
- 238000011068 loading method Methods 0.000 claims description 10
- 230000005484 gravity Effects 0.000 claims description 5
- 238000004065 wastewater treatment Methods 0.000 claims 1
- MMDJDBSEMBIJBB-UHFFFAOYSA-N [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] Chemical compound [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] MMDJDBSEMBIJBB-UHFFFAOYSA-N 0.000 abstract description 25
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 24
- 239000010865 sewage Substances 0.000 abstract description 16
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 13
- 230000008569 process Effects 0.000 abstract description 11
- 238000003933 environmental pollution control Methods 0.000 abstract description 3
- 239000002245 particle Substances 0.000 description 17
- 239000012528 membrane Substances 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 230000003647 oxidation Effects 0.000 description 8
- 238000007254 oxidation reaction Methods 0.000 description 8
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 6
- 239000003344 environmental pollutant Substances 0.000 description 6
- 231100000719 pollutant Toxicity 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 239000011258 core-shell material Substances 0.000 description 5
- 238000011010 flushing procedure Methods 0.000 description 5
- 230000000813 microbial effect Effects 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 238000006555 catalytic reaction Methods 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 229910001447 ferric ion Inorganic materials 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 229910014033 C-OH Inorganic materials 0.000 description 2
- 229910014570 C—OH Inorganic materials 0.000 description 2
- JVMRPSJZNHXORP-UHFFFAOYSA-N ON=O.ON=O.ON=O.N Chemical compound ON=O.ON=O.ON=O.N JVMRPSJZNHXORP-UHFFFAOYSA-N 0.000 description 2
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000012844 infrared spectroscopy analysis Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000000018 DNA microarray Methods 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 229910017135 Fe—O Inorganic materials 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- NULAJYZBOLVQPQ-UHFFFAOYSA-N N-(1-naphthyl)ethylenediamine Chemical compound C1=CC=C2C(NCCN)=CC=CC2=C1 NULAJYZBOLVQPQ-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 239000003242 anti bacterial agent Substances 0.000 description 1
- 229940088710 antibiotic agent Drugs 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000007385 chemical modification Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 239000000701 coagulant Substances 0.000 description 1
- 239000011246 composite particle Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 125000004185 ester group Chemical group 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical group Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- 238000001471 micro-filtration Methods 0.000 description 1
- 230000001546 nitrifying effect Effects 0.000 description 1
- 235000015097 nutrients Nutrition 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000003921 particle size analysis Methods 0.000 description 1
- 230000002572 peristaltic effect Effects 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 238000005375 photometry Methods 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 230000027756 respiratory electron transport chain Effects 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
-
- 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
- C02F3/02—Aerobic processes
- C02F3/10—Packings; Fillings; Grids
- C02F3/105—Characterized by the chemical composition
-
- 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
- C02F3/02—Aerobic processes
- C02F3/10—Packings; Fillings; Grids
- C02F3/105—Characterized by the chemical composition
- C02F3/107—Inorganic materials, e.g. sand, silicates
-
- 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
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
- C02F3/1236—Particular type of activated sludge installations
- C02F3/1268—Membrane bioreactor systems
-
- 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
- C02F3/28—Anaerobic digestion processes
-
- 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
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Organic Chemistry (AREA)
- Water Supply & Treatment (AREA)
- Environmental & Geological Engineering (AREA)
- Hydrology & Water Resources (AREA)
- Nanotechnology (AREA)
- Biodiversity & Conservation Biology (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- General Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Composite Materials (AREA)
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
Abstract
The invention relates to a nano zero-valent iron filler, a preparation method thereof and application thereof in denitrification, belonging to the technical field of environmental pollution control. The invention discloses a preparation method of a nano zero-valent iron filler, which comprises the following steps: a proper amount of polyethylene filler is selected and put into a NaOH solution of 300-500 g/L, the polyethylene filler is immersed completely by NaOH, the polyethylene filler is taken out after being immersed for 24-72 hours, the polyethylene filler is washed by deionized water until the washing liquid is neutral, and the polyethylene filler is taken out and dried at 60-90 ℃; placing the pretreated polyethylene filler into ferrous sulfate solution, uniformly mixing and soaking; adding tea polyphenol solution, mixing, and soaking; and taking out the filler, washing with deionized water, and drying to obtain the nano zero-valent iron filler. According to the invention, simulated domestic sewage is taken as a treatment object, nano zero-valent iron filler is added into an aerobic tank of an A/O/-MBR reactor, after 130d of operation, the concentration of nitrate nitrogen in effluent is 5.8-8.9 mg/L, the total nitrogen removal rate is 73.5% -82.4%, the process is friendly, and no secondary pollution is caused.
Description
Technical Field
The invention relates to a nano zero-valent iron filler, a preparation method thereof and application thereof in denitrification, belonging to the technical field of environmental pollution control.
Background
In recent years, with the gradual advancement of the improvement of the living standard of people in China and the construction of ecological civilization, the urban sewage discharge standard is increasingly strict, and the exceeding of nitrogen is one of the important restriction factors for realizing the standard discharge of municipal sewage. In general, the conventional biological denitrification process for sewage includes two steps, namely, firstly converting ammonia nitrogen in sewage into nitrate nitrogen through nitrification under aerobic conditions, and then converting the nitrate nitrogen into nitrogen through denitrification under anoxic conditions, so as to realize denitrification. Researches show that the removal of ammonia nitrogen in sewage is easy to realize, the removal rate is generally more than 90%, the process of converting nitrate nitrogen into nitrogen through denitrification is easily influenced by environmental factors, including carbon sources, temperature, toxic substances and the like, is a limiting step in the traditional biological denitrification process, and results in accumulation of nitrate nitrogen, and the total nitrogen in effluent cannot reach the emission standard. Therefore, how to improve the nitrate nitrogen removal effect of sewage treatment systems has received extensive attention from related scholars.
The nano zero-valent iron is used as a strong reducing agent and is widely used for reducing and degrading nutrient elements (nitrogen and phosphorus), heavy metals (Cr, as, cu, pb and the like), chlorinated organic pollutants, antibiotics and other pollutants in sewage. Reducing and removing NO in sewage by taking nano zero-valent iron as electron donor 3 - And the removal rate of N is over 90 percent, and the removal effect is good. However, nano zero-valent ironAgglomeration and oxidation are easy to occur in the preparation, storage and use processes, the electron transfer efficiency between the catalyst and pollutants is reduced, and the catalyst is difficult to fully play a role. The method of surface chemical modification, doping inert elements (N, si, cu), self oxidation to form a 'core-shell' structure and the like can improve the anti-agglomeration and oxidation resistance of the nano zero-valent iron, but the method has the problems of unsatisfactory effect, complex preparation or modification process, secondary pollution and the like.
Disclosure of Invention
The invention provides a method for preparing nano zero-valent iron filler, which uses tea polyphenol extracted from plants as a reducing agent to prepare nano zero-valent iron by a one-step method, and the formed core-shell structure can protect the nano zero-valent iron of the core from being oxidized, is not easy to agglomerate, is simple and convenient to operate and has environmental-friendly process.
The first object of the present invention is to provide a method for preparing a nano zero-valent iron filler, the method comprising the steps of:
(1) Pretreatment of polyethylene filler: and (3) putting a proper amount of polyethylene filler into a NaOH solution of 300-500 g/L, taking out the polyethylene filler after soaking for 24-72 h until the washing liquid is neutral, taking out the polyethylene filler, and drying at 60-90 ℃.
(2) Placing the pretreated polyethylene filler into ferrous sulfate solution, uniformly mixing and soaking;
(3) Adding tea polyphenol solution, mixing, and soaking;
(4) And taking out the filler, washing with deionized water, and drying to obtain the nano zero-valent iron filler.
In one embodiment of the present invention, the mass ratio of polyethylene filler to ferrous ion in the step (2) is 10 to 50:1.
in one embodiment of the present invention, the mass ratio of polyethylene filler to ferrous ion in the step (2) is 20:1.
in one embodiment of the invention, the mass ratio of ferrous ions to tea polyphenol in the mixed system in the step (3) before the reaction is 0.2-0.8: 1.
in one embodiment of the present invention, in the step (2), the concentration of ferrous ions in the ferrous sulfate solution is 1-5 g/L, and the ferrous sulfate solution is used in an amount based on immersing the polyethylene filler.
In one embodiment of the present invention, the soaking time in the step (2) is 30 to 60 minutes, and the temperature is 40 to 70 ℃.
In one embodiment of the present invention, the soaking temperature in the step (2) is 50 ℃.
In one embodiment of the present invention, the soaking time in the step (3) is 1 to 5d, and the temperature is 40 to 70 ℃.
In one embodiment of the present invention, the drying temperature in the step (4) is 40 to 60 ℃ and the drying time is 12 to 24 hours.
The second object of the invention is to provide the nano zero-valent iron filler prepared by the method, wherein the loading amount of nano zero-valent iron on the filler is 2-5 mg/g.
In one embodiment of the invention, the nano zero-valent iron filler is sheet-shaped and has a specific surface area of 10-100 cm 2 Per gram, the specific gravity is 0.85-0.95 kg/L, the diameter is 25-35 mm, and the thickness is 1.0-1.5 mm.
In one embodiment of the invention, the nano zero-valent iron filler is in a sheet shape and has a specific surface area of 57.89cm 2 And/g, specific gravity of 0.95kg/L, diameter of 30mm and thickness of 1.1mm.
The third object of the invention is to provide the application of the nano zero-valent iron filler in denitrification of biological sewage treatment.
In one embodiment of the invention, the nano zero-valent iron filler is applied to denitrification of biological sewage treatment. The loading capacity of the nano zero-valent iron on the filler is 2-5 mg/g, the filler is sheet-shaped, and the specific surface area is 57.89cm 2 And/g, specific gravity of 0.95kg/L, diameter of 30mm and thickness of 1.1mm. The concentration of nitrate nitrogen in the effluent is 5.8-8.9 mg/L, and the total nitrogen removal rate reaches 73.5% -82.4%.
The invention has the beneficial effects that:
(1) According to the invention, the load of the tea polyphenol-nano zero-valent iron is realized by utilizing hydrogen bonds between the tea polyphenol and the polyethylene filler, and oxygen in the tea polyphenol structure is associated with the nano zero-valent iron in a covalent bond mode, so that the oxidation resistance of the nano zero-valent iron is improved.
(2) The invention provides a method for preparing nano zero-valent iron filler, wherein the loading amount of nano zero-valent iron on the filler is 2-5 mg/g, the loading effect is good, and the preparation cost is low.
(3) The nanometer zero-valent iron filler prepared by the invention is used for an aerobic tank of an A/O-MBR reactor, the concentration of nitrate nitrogen in system effluent is 5.8-8.9 mg/L, the total nitrogen removal rate is 73.5-82.4%, the effluent quality is excellent, and the application prospect is wide.
(4) The nanometer zero-valent iron filler prepared by the invention has stable use effect and long service period, and the removal rate of nitrate nitrogen is not changed greatly after 130 days.
The nano zero-valent iron filler prepared by the characterization of the invention discovers that the nano zero-valent iron is wrapped in tea polyphenol to form a core-shell structure, so that the nano zero-valent iron is not easy to agglomerate and oxidize (figures 1, 2 and 3). Characterization also shows that composite particles formed by nano zero-valent iron and tea polyphenol are uniformly dispersed on the surface of polyethylene filler to form a large number of active sites for pollutant removal. The structure is beneficial to ensuring the high efficiency and stability of the removal effect.
The nanometer zero-valent iron is positioned in the core-shell structure, so that the nanometer zero-valent iron has a certain slow release effect, the utilization rate of the nanometer zero-valent iron is high, and the service cycle is long.
(5) The nano zero-valent iron filler prepared by the method has a simple use process. The nanometer zero-valent iron is loaded on polyethylene filler commonly used in environmental pollution control systems. In the use process, a processing unit is not required to be added, the structural transformation of equipment is not required, and the preparation and the use are convenient.
(6) The nano zero-valent iron filler prepared by the method is environment-friendly. The tea polyphenol used in the preparation process of the nano zero-valent iron filler is biodegradable and does not relate to organic solvents and toxic and harmful substances; the nano zero-valent iron filler is used for reducing nitrate nitrogen in a pollution treatment system and then converting the nitrate nitrogen into ferric ions, and the ferric ions can be used as a coagulant to further remove pollutants including phosphorus in water, so that the process is friendly and no secondary pollution is caused.
Drawings
Fig. 1 is a scanning electron micrograph of a modified polyethylene filler (panels a and B), a nano zero valent iron filler (panels C, D and E), and a particle size distribution plot of nano zero valent iron filler surface particles (panel F).
Fig. 2 is a spectrum of fourier infrared spectroscopy analysis of tea polyphenols (panel a), modified polyethylene filler (panel B) and nano zero-valent iron filler (panel C).
Fig. 3 is a spectrum of x-ray photoelectron spectra of a nano zero-valent iron filler (fig. a), a nano zero-valent iron filler (fig. B) after reaction with nitrate nitrogen, and a nano zero-valent iron filler (fig. C) after microbial catalysis of nitrate nitrogen.
Detailed Description
The following description of the preferred embodiments of the present invention is provided for better illustration of the invention, and should not be construed as limiting the invention.
The polyethylene filler used in the examples and comparative examples of the present invention was of the specification Mutag BioChip 30 TM Purchased from Shanghai Kogyo environmental engineering Co.
The detection method involved in the following examples is as follows:
determination of iron concentration:taking a certain amount of nano zero-valent iron filler, placing the nano zero-valent iron filler in 100mL of 0.50% HNO 3 After soaking in the solution for 12 hours, the filler is taken out and washed by deionized water, and after the solution is filtered by a 0.45 mu m filter membrane, the concentration of iron is measured by an atomic absorption method.
Determination of nitrate nitrogen concentration:NO 3 - the concentration of-N is determined by UV spectrophotometry, NO 2 - The concentration of-N was determined by N- (1-naphthyl) -ethylenediamine photometry.
Example 1: preparation of nano zero-valent iron filler
Pretreatment of polyethylene filler: and (3) selecting a proper amount of polyethylene filler, putting the polyethylene filler into a NaOH solution of 300-500 g/L, taking out the polyethylene filler after soaking for 24-72 h until the washing liquid is neutral, taking out the polyethylene filler, and drying at 80 ℃.
A proper amount of polyethylene filler is put into ferrous sulfate solution with the concentration of ferrous ions of 1-5 g/L, and the mass ratio of the polyethylene filler to the ferrous ions is 20:1, soaking for 30-60 min after uniformly mixing and immersing, wherein the temperature is 50 ℃; then adding a proper amount of tea polyphenol solution with the concentration of 1-10 g/L to ensure that the mass ratio of ferrous ions to tea polyphenol is 0.2-0.8: 1, immersing after uniformly mixing, wherein the immersing time is 1-5 d, and the temperature is 50 ℃; and then taking out the filler, flushing with deionized water, and drying at 45 ℃ for 12 hours to obtain the nano zero-valent iron filler No. 1.
Through tests, the loading amount of nano zero-valent iron on the filler No. 1 is 2-5 mg/g.
Fig. 1 is a scanning electron micrograph of a modified polyethylene filler (panels a and B), a nano zero valent iron filler (panels C, D and E), and a particle size distribution plot of nano zero valent iron filler surface particles (panel F). It can be seen that the modified polyethylene has a rough surface and exhibits obvious cracks, which indicates that NaOH corrosion effectively improves the roughness of its surface, which is advantageous for subsequent nano zero-valent iron loading. After the nano zero-valent iron is loaded, irregularly-shaped particles are distributed on the surface of the nano zero-valent iron filler, and particle size analysis shows that the particle size of 66.62% of particles is 62.74 +/-0.04 nm, and the particle size of 8.08% of particles is 333.70 +/-0.53 nm. The prior literature shows that the particle size of the nano zero-valent iron is about 20-40 nm, so that the research shows that the particle size of the nano zero-valent iron is larger, which is related to secondary encapsulation of tea polyphenol in the preparation process, increases the thickness of the shell structure of the tea polyphenol-nano zero-valent iron particle, and improves the oxidation resistance of the nano zero-valent iron.
Characterization showed that the surface of the filler was uniformly distributed with irregularly shaped particles, wherein 66.62% of the particles had a particle size of 62.74nm and 8.08% of the particles had a particle size of 333.70nm. The nano zero-valent iron is wrapped in a tea polyphenol core-shell structure, so that the nano zero-valent iron is not easy to agglomerate and oxidize in the transportation and storage processes.
Fourier infrared spectrum analysis shows that in the preparation process of the composite filler, the loading of the tea polyphenol-nano zero-valent iron is realized by hydrogen bonds between the tea polyphenol and the polyethylene filler, and oxygen in the tea polyphenol structure is associated with the nano zero-valent iron in a covalent bond mode, so that the oxidation resistance of the nano zero-valent iron is improved.
Fig. 2 is a spectrum of fourier infrared spectroscopy analysis of tea polyphenols (panel a), modified polyethylene filler (panel B) and nano zero-valent iron filler (panel C). The formation of the tea polyphenol-nano zero valent iron complex results in 3364.36cm of nano zero valent iron filler compared with the tea polyphenol and the modified polyethylene filler -1 The intensity of the broad peak at the position is reduced, and 1143.94cm -1 The disappearance of the stretching vibration peak indicates that Ar-OH and ester group (C-O-C) in the tea polyphenol structure play an important role in the preparation process of zero-valent iron. C-OH (1066.01 cm) -1 And 1019.03cm -1 ) And benzene ring skeleton (1611.87 cm) -1 ) The tensile vibration peak of (C) shows red shift, which indicates that C-OH and benzene ring skeleton participate in Fe 2+ Or in the form of common electrons with iron (0/II). At the same time, a new absorption peak appears at 518.05cm -1 Here, due to the telescopic vibration of Fe-O bond, oxygen in the tea polyphenol structure is associated with zero-valent iron in a covalent bond form in the preparation process, so that the oxidation resistance of the zero-valent iron is improved. Therefore, in the preparation process of the composite filler, the loading of the tea polyphenol-nano zero-valent iron is realized by hydrogen bonds between the tea polyphenol and the modified polyethylene, and oxygen in the tea polyphenol structure is associated with the nano zero-valent iron in a covalent bond form, so that the oxidation resistance of the nano zero-valent iron is improved.
Comparative example 1:
referring to example 1, only the pretreatment step of the polyethylene filler was omitted, and the nano zero-valent iron filler # 2 was prepared.
Comparative example 2:
referring to example 1, only the difference is that the ferrous sulfate solution is replaced with ferric chloride solution, wherein the concentration of ferric ions is 1-5 g/L, and nano zero-valent iron filler 3# is obtained.
Example 2: application contrast of nano zero-valent iron filler in denitrification of sewage biological treatment
The nano zero-valent iron fillers of example 1 and comparative examples 1 and 2 were respectively added to the O tank (aerobic tank) of the A/O-MBR reactor with the simulated domestic sewage as the treatment object). Wherein the nano zero-valent iron filler of the embodiment 1 has the loading capacity of 2-5 mg/g of nano zero-valent iron, the filler is flaky and the specific surface area is 57.89cm 2 And/g, specific gravity of 0.95kg/L, diameter of 30mm and thickness of 1.1mm. The concentrations of COD, ammonia nitrogen, total nitrogen and total phosphorus of the simulated domestic sewage are 350+/-20, 25+/-2, 38+/-2 and 2.7+/-0.2 mg/L respectively. The effective volumes of the anoxic tank and the aerobic tank are 4.5L. The membrane component is polyvinylidene fluoride micro-filtration membrane, purchased from Shanghai Zi feature environmental protection technology Co., ltd, and the effective filtration area is 340cm 2 The aeration device is arranged below the membrane component and is arranged in the aerobic tank to play roles in supplying oxygen and flushing the membrane surface. The membrane component is connected with a peristaltic pump through a silica gel tube, and the membrane flux is controlled to be 20L/(m) by adjusting the pump speed 2 H), constant flux operation. Reflux ratio of nitrifying liquid is 4:1, the operation temperature is controlled at 25+/-1 ℃, and the filling ratio of the filler is 30%. When the transmembrane pressure difference rises to 25kPa, the membrane assembly is taken out for offline cleaning, the method is that sponge balls are used for scrubbing, deionized water is used for flushing a filter cake layer on the surface of the membrane, if the membrane flux is unstable, the membrane is soaked for 12 hours by using 0.3% (V/V) NaClO solution, then deionized water is used for flushing and soaking for 2 hours, and back flushing is carried out for 5 minutes.
TABLE 1
The test result shows that the nano zero-valent iron filler prepared in the embodiment 1 is used in an aerobic tank of an A/O-MBR reactor, the concentration of nitrate nitrogen in effluent is between 5.8 and 8.9mg/L, the total nitrogen removal rate is 73.5 to 82.4 percent, the total nitrogen concentration of the effluent accords with the first-level A standard of pollutant emission standard (GB 18918 2002) of urban sewage treatment plants in China, and the membrane pollution rate is 1.20kPa/d after the reactor is operated for 130 d. The total nitrogen removal rates of comparative examples 1 and 2 are 45.5% -55.8% and 42.2% -49.6%, the nitrate nitrogen concentration in the effluent is 15.5-18.7 and 15.8-19.6 mg/L, the effluent quality is higher than the first grade A standard of the pollutant emission standard (GB 18918 2002) of urban sewage treatment plants in China, and meanwhile, the membrane pollution rates are also higher and are respectively 1.86 and 1.85kPa/d.
Fig. 3 is a spectrum of x-ray photoelectron spectra of a nano zero-valent iron filler (fig. a), a nano zero-valent iron filler (fig. B) after reaction with nitrate nitrogen, and a nano zero-valent iron filler (fig. C) after microbial catalysis of nitrate nitrogen. It can be seen that the existence of an N1s peak can be clearly seen on the surface of the nano zero-valent iron filler after the reaction. Further analysis of the N1s deconvolution peak, the presence of ammonia nitrogen (399.99 eV), nitrite nitrogen (404.98 eV) and nitrate nitrogen (407.00 eV) was found on the surface of the nano zero-valent iron filler after reaction with nitrate nitrogen, wherein the presence of ammonia nitrogen and nitrite nitrogen was attributed to chemical reduction between nano zero-valent iron and nitrate nitrogen, and the presence of nitrate nitrogen was attributed to adsorption or co-precipitation of nano zero-valent iron filler. After the microbial catalysis nitrate nitrogen reaction, ammonia nitrogen (399.01 eV and 400.02 eV) only exists on the surface of the nano zero-valent iron filler, and the content of the nano zero-valent iron filler is obviously higher than that of the nano zero-valent iron filler after the microbial catalysis nitrate nitrogen reaction, which indicates that the existence of the microbial can degrade and remove the shell' -tea polyphenol on the surface of the nano zero-valent iron, restore the activity of the nano zero-valent iron and promote the chemical reaction between the nano zero-valent iron and the nitrate nitrogen.
While the invention has been described with reference to the preferred embodiments, it is not limited thereto, and various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (8)
1. A method for preparing a nano zero-valent iron filler, the method comprising the steps of:
(1) Pretreatment of polyethylene filler: putting a proper amount of polyethylene filler into a NaOH solution of 300-500 g/L, taking out the polyethylene filler after soaking for 24-72 h until the washing liquid is neutral, taking out the polyethylene filler, and drying at 60-90 ℃;
(2) Placing the pretreated polyethylene filler into ferrous sulfate solution, uniformly mixing and soaking;
(3) Then adding tea polyphenol solution to make the mass ratio of ferrous ion and tea polyphenol be 0.2-0.8: 1, uniformly mixing and soaking;
(4) Taking out the filler, washing with deionized water, and drying to obtain nano zero-valent iron filler;
wherein the mass ratio of the polyethylene filler to the ferrous ions in the step (2) is 10-50:1.
2. The method according to claim 1, wherein in the step (2), the concentration of ferrous ions in the ferrous sulfate solution is 1-5 g/L, and the ferrous sulfate solution is used in an amount based on immersing the polyethylene filler.
3. The method according to claim 1, wherein the soaking time in the step (2) is 30 to 60 minutes and the temperature is 40 to 70 ℃.
4. The method according to claim 1, wherein the soaking time in the step (3) is 1 to 5d and the temperature is 40 to 70 ℃.
5. The method according to claim 1, wherein the drying temperature in the step (4) is 40 to 60 ℃ and the drying time is 12 to 24 hours.
6. The nano zero-valent iron filler prepared by the method of any one of claims 1-5, wherein the loading amount of nano zero-valent iron on the filler is 2-5 mg/g.
7. The nano zero-valent iron filler according to claim 6, wherein the filler is sheet-shaped and has a specific surface area of 10-100 cm 2 Per gram, the specific gravity is 0.85-0.95 kg/L, the diameter is 25-35 mm, and the thickness is 1.0-1.5 mm.
8. The use of the nano zero-valent iron filler of claim 7 in denitrification of biological wastewater treatment.
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