CN118145779A - Method for high-efficiency water treatment by using innovative nanocomposite - Google Patents
Method for high-efficiency water treatment by using innovative nanocomposite Download PDFInfo
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- CN118145779A CN118145779A CN202410580217.8A CN202410580217A CN118145779A CN 118145779 A CN118145779 A CN 118145779A CN 202410580217 A CN202410580217 A CN 202410580217A CN 118145779 A CN118145779 A CN 118145779A
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 41
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 49
- 229920000747 poly(lactic acid) Polymers 0.000 claims abstract description 45
- 238000006243 chemical reaction Methods 0.000 claims abstract description 44
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims abstract description 42
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 37
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 claims abstract description 26
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims abstract description 24
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- 239000011790 ferrous sulphate Substances 0.000 claims abstract description 23
- 235000003891 ferrous sulphate Nutrition 0.000 claims abstract description 23
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract description 23
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims abstract description 23
- 239000012279 sodium borohydride Substances 0.000 claims abstract description 23
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- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims abstract description 22
- 238000001035 drying Methods 0.000 claims abstract description 19
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- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- 239000011651 chromium Substances 0.000 description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 5
- 229910052804 chromium Inorganic materials 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
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- MCPLVIGCWWTHFH-UHFFFAOYSA-L methyl blue Chemical compound [Na+].[Na+].C1=CC(S(=O)(=O)[O-])=CC=C1NC1=CC=C(C(=C2C=CC(C=C2)=[NH+]C=2C=CC(=CC=2)S([O-])(=O)=O)C=2C=CC(NC=3C=CC(=CC=3)S([O-])(=O)=O)=CC=2)C=C1 MCPLVIGCWWTHFH-UHFFFAOYSA-L 0.000 description 2
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- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
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- 229910052742 iron Inorganic materials 0.000 description 1
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- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
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- 239000002184 metal Substances 0.000 description 1
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Classifications
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- 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
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- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The invention relates to a method for high-efficiency water treatment by using innovative nanocomposite materials, which comprises the steps of dissolving ferrous sulfate in deionized water, adding sodium borohydride, slowly mixing and reacting in inert atmosphere to prepare nano zero-valent iron, and purifying by centrifugation or magnetic separation, ethanol washing and vacuum drying. Next, polylactic acid was dissolved in chloroform, nano zero-valent iron was added to form a coating, and then chloroform was removed by a rotary evaporator and dried. And finally, adding the coated nano particles into absolute ethyl alcohol containing acrylic acid and azodiisobutyronitrile to carry out grafting carboxyl group reaction, washing with ethyl alcohol after the reaction and drying in vacuum to obtain a final grafted product. NZVI can reduce heavy metal ions, decompose organic pollutants, and the PLA shell layer improves the oxidation resistance and prolongs the activity. The design makes the material adapt to different water quality, and the magnetic component is convenient for retrieve, has improved sustainability and economic nature, provides environment-friendly high-efficient solution for water treatment.
Description
Technical Field
The invention relates to the technical field of water treatment, in particular to a method for efficiently treating water by using an innovative nanocomposite.
Background
In the fields of environmental remediation and industrial wastewater treatment, it is a challenge to rapidly and efficiently treat high concentrations of heavy metal ions, especially in the face of sudden high pollution events caused by industrial accidents or irregular emissions. Currently widely used adsorbent materials, such as activated carbon, zeolites or various clay materials, often expose their inherent performance limitations when dealing with these highly contaminated scenes.
First, one of the main limitations of these conventional adsorbent materials is their limited adsorption capacity. Chemically, the adsorption capacity of these materials is physically limited by their surface area and available adsorption sites. When high concentrations of heavy metal ions are encountered, these adsorption sites are quickly fully occupied, resulting in a rapid saturation of their surface. This saturation phenomenon greatly limits the effectiveness of the material in continuously treating high concentrations of contaminants because once the surface adsorption sites are occupied, additional contaminants cannot be effectively removed, resulting in a dramatic decrease in overall adsorption efficiency.
This dramatic drop in efficiency not only affects the process results, but also increases the process cost and time. In practice, this means that the adsorbent material needs to be replaced or regenerated more frequently, thereby increasing the operating cost and maintenance effort. In addition, high concentration contamination events often require rapid response and immediate disposal, and this disadvantage of conventional materials severely hampers the ability to rapidly remove heavy metals, potentially resulting in long periods of environmental contamination, increasing the difficulty and cost of environmental recovery.
In view of the obvious drawbacks of these conventional materials in treating high concentrations of heavy metal ions, it is becoming urgent to develop new materials or to modify existing materials to increase their adsorption capacity and treatment efficiency. These new or improved materials need to have higher adsorption capacity, better regeneration capacity and longer service life in order to more effectively cope with high concentration heavy metal pollution.
Disclosure of Invention
In order to solve or partially solve the problems existing in the related art, the present application provides a method for performing efficient water treatment using innovative nanocomposite materials.
The first aspect of the application provides a preparation method of a nanocomposite for water treatment, S1, preparing nano zero-valent iron (NZVI):
Dissolving 5.0-10.0g of ferrous sulfate in 250 mL deionized water, and fully stirring until the ferrous sulfate is completely dissolved;
slowly adding 2.2-4.4g of sodium borohydride into the other 250 mL deionized water, and fully stirring until the sodium borohydride is completely dissolved;
Slowly dropwise adding the sodium borohydride solution into the ferrous sulfate solution in an inert atmosphere at the dropwise adding rate of 1-5mL/min;
maintaining the reaction for 15-60 minutes, and keeping stirring to ensure sufficient reaction;
Immediately removing unreacted residues through centrifugation or magnetic separation after the reaction, collecting nano zero-valent iron, washing with ethanol for 2-3 times, and finally drying and preserving in vacuum;
S2, coating polylactic acid (PLA):
Dissolving 1.0g to 2.0g of polylactic acid in 100-200 mL chloroform, and fully stirring until the polylactic acid is completely dissolved;
adding the prepared nano zero-valent iron into the polylactic acid solution, and continuously stirring for 0.5-2 hours to form uniform coating;
Removing chloroform by a rotary evaporator at 25-45 ℃, collecting coated nano zero-valent iron, and drying for later use;
s3, grafting carboxyl groups:
Dissolving 0.5-1.0g of acrylic acid and 0.05-0.1g of azodiisobutyronitrile in 50-100 mL absolute ethyl alcohol, and fully stirring;
adding nano zero-valent iron coated with polylactic acid into the mixed solution of the acrylic acid and the azodiisobutyronitrile;
The reaction is kept for 8 to 12 hours at 50 to 70 ℃ to ensure that the acrylic acid can be fully grafted on the surface of PLA;
after the reaction, the grafted product is washed with ethanol, unreacted monomers and initiator are removed, and the final product is obtained by centrifugal separation and then drying in vacuum.
Further, the mass of ferrous sulfate used was 7.5 grams.
Further, the mass of sodium borohydride used was 3.3 grams.
Further, the reaction maintenance time in S1 was 0.5h.
Further, the mass of polylactic acid was 1.5 g.
Further, the volume of chloroform to dissolve polylactic acid was 150 mL.
Further, the temperature at which chloroform was removed by the rotary evaporator was 35 ℃.
Further, the mass of acrylic acid used for grafting carboxyl groups was 0.75 g, and the mass of azobisisobutyronitrile was 0.075 g.
Further, the temperature of the grafting reaction was 60℃and the time of the grafting reaction was 12 hours.
In a second aspect the present invention provides a nanocomposite for water treatment, the nanocomposite being obtainable according to the above-described method of preparation.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
The beneficial technical effects of the invention are as follows:
In the design of the nanocomposite of the present invention, we created a system with excellent water handling properties by combining nano zero-valent iron (NZVI) and polylactic acid (PLA) shells. The system not only can effectively remove heavy metals and organic pollutants in water, but also can adapt to different environmental changes through an inherent response control mechanism, thereby realizing high-efficiency and durable pollutant removal effect.
(1) Synergistic effects and chemical kinetics
The NZVI of the core is responsible for reducing toxic metal ions dissolved in water directly by chemical reduction to a less harmful state. For example, cr (VI) is reduced to Cr (III), and the toxicity and flowability of this form of chromium is significantly reduced. In addition, NZVI also exhibits good reducing power for organic contaminants, such as reducing a variety of organic dyes to less active compounds.
(2) The introduction of the PLA shell not only provides physical protection and avoids the rapid inactivation of NZVI due to oxidation, but also enhances the adsorption and fixation of heavy metals through the carboxyl groups grafted on the surface of the PLA shell. These carboxyl groups can effectively capture and immobilize heavy metal ions such as lead, copper, etc. from water by ion exchange and complexation. This capture is reversible, facilitating the re-release of these metals by appropriate treatment, enabling the reuse of the material.
(3) Environmental responsiveness control
Environmental responsiveness control of materials is accomplished by their design to be sensitive to specific environmental variables, thereby regulating their behavior during water treatment. The introduction of carboxyl groups is critical for the control of responsiveness, and first, according to the collision theory, an increase in the concentration of metal ions leads to an increase in the frequency of collisions between carboxyl groups and metal ions, thereby increasing the chance of complex formation. Second, the coordination of the carboxyl group forms a coordination bond with the metal ion through the lone pair of electrons of the oxygen atom, and increasing the concentration of the metal ion enhances the coordination. In addition, the thermodynamic behavior of the system in high concentration environments also promotes the progress of the complexation reaction, since such reactions are typically exothermic, and as the concentration of reactants increases, the exotherm of the reaction increases, enhancing the driving force of the reaction. The factors are combined, so that the efficiency of the reaction of the carboxyl functional group and the metal ion is obviously improved when the concentration of the metal ion is higher, and the overall removing capacity of the adsorption material is improved.
Drawings
FIG. 1 is an electron micrograph of the surface of the final product of example 1 of the present invention.
When observed under a Scanning Electron Microscope (SEM), a large number of uniformly distributed spherical particles are visible, and the particles are in a form of nano zero-valent iron (nZVI) coated with polylactic acid (PLA) and grafted with carboxyl groups. Each particle had a smooth surface, a particle size of between about 20-50 nm, indicating good dispersibility and uniform size. The polylactic acid coating layer shows a slight roughness of the particle surface under an electron microscope because the grafted carboxyl groups increase the density of the surface functional groups.
No obvious agglomeration phenomenon exists among the particles, which shows the success of the polylactic acid coating layer, and effectively prevents the oxidation and agglomeration of the nano iron particles. The grafted carboxyl groups provide additional hydrophilicity and reactivity to the particles.
Overall, these nanoparticles exhibit the characteristics of uniformity, good dispersibility, and good surface modification, which suggests that the material has good application potential in the field of water treatment.
Detailed Description
The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.
The application provides a preparation method of a nanocomposite for water treatment, which comprises the following steps of S1, preparing nano zero-valent iron (NZVI):
Dissolving 5.0-10.0g of ferrous sulfate in 250 mL deionized water, and fully stirring until the ferrous sulfate is completely dissolved;
slowly adding 2.2-4.4g of sodium borohydride into the other 250 mL deionized water, and fully stirring until the sodium borohydride is completely dissolved;
Slowly dropwise adding the sodium borohydride solution into the ferrous sulfate solution in an inert atmosphere at the dropwise adding rate of 1-5mL/min;
maintaining the reaction for 15-60 minutes, and keeping stirring to ensure sufficient reaction;
Immediately removing unreacted residues through centrifugation or magnetic separation after the reaction, collecting nano zero-valent iron, washing with ethanol for 2-3 times, and finally drying and preserving in vacuum;
S2, coating polylactic acid (PLA):
Dissolving 1.0g to 2.0g of polylactic acid in 100-200 mL chloroform, and fully stirring until the polylactic acid is completely dissolved;
adding the prepared nano zero-valent iron into the polylactic acid solution, and continuously stirring for 0.5-2 hours to form uniform coating;
Removing chloroform by a rotary evaporator at 25-45 ℃, collecting coated nano zero-valent iron, and drying for later use;
s3, grafting carboxyl groups:
Dissolving 0.5-1.0g of acrylic acid and 0.05-0.1g of azodiisobutyronitrile in 50-100 mL absolute ethyl alcohol, and fully stirring;
adding nano zero-valent iron coated with polylactic acid into the mixed solution of the acrylic acid and the azodiisobutyronitrile;
The reaction is kept for 8 to 12 hours at 50 to 70 ℃ to ensure that the acrylic acid can be fully grafted on the surface of the polylactic acid;
after the reaction, the grafted product is washed with ethanol, unreacted monomers and initiator are removed, and the final product is obtained by centrifugal separation and then drying in vacuum.
The nanocomposite mainly removes heavy metals and organic pollutants in water through the synergistic effect of nano zero-valent iron (NZVI) and polylactic acid (PLA) shells. The NZVI core reduces heavy metal ions such as chromium and mercury to a more nontoxic form by chemical reduction, and simultaneously reduces and decomposes organic pollutants. The PLA shell layer not only physically protects NZVI from being oxidized too fast and prolongs the activity period of the NZVI, but also enhances the adsorption capacity to heavy metals through surface grafted carboxyl groups, and stably captures ions through ion exchange and coordination mechanisms. In addition, the responsiveness design of the material enables the material to adjust the adsorption characteristic and the treatment efficiency according to the heavy metal concentration of the water body, and ensures that the material can be efficiently acted under different environmental conditions. The magnetic components are integrated, so that the used material can be recycled through a magnetic separation technology, and the sustainability and economic benefit of the material are enhanced. Through the synergistic effect of multiple mechanisms, the material realizes the effective removal of water quality pollutants, reduces the environmental impact and provides an efficient and environment-friendly water treatment solution.
In one embodiment of the present application, the ferrous sulfate used has a mass of 7.5 grams.
In one embodiment of the present application, sodium borohydride is used with a mass of 3.3 grams.
In one embodiment of the present application, the reaction maintenance time in S1 is 0.5h.
In one embodiment of the present application, the polylactic acid has a mass of 1.5 grams.
In one embodiment of the present application, the volume of chloroform to dissolve the polylactic acid is 150 mL.
In one embodiment of the present application, the temperature of the rotary evaporator to remove chloroform is 35 ℃.
In one embodiment of the present application, the acrylic mass used to graft the carboxyl groups is 0.75 grams and the azobisisobutyronitrile mass is 0.075 grams.
In one embodiment of the present application, the grafting reaction is carried out at a temperature of 60℃and for a time of 12 hours.
For clarity, the following examples are provided in detail.
Example 1: s1, preparing nano zero-valent iron (NZVI):
7.5g of ferrous sulfate is dissolved in 250 mL deionized water, and the mixture is fully stirred until the ferrous sulfate is completely dissolved;
Slowly adding 3.3g of sodium borohydride into the other 250 mL deionized water, and fully stirring until the sodium borohydride is completely dissolved;
Slowly dropwise adding the sodium borohydride solution into the ferrous sulfate solution in an inert atmosphere, wherein the dropwise adding rate is 3mL/min;
The reaction was maintained for 30 minutes with stirring to ensure adequate reaction;
Immediately removing unreacted residues through centrifugation or magnetic separation after the reaction, collecting nano zero-valent iron, washing with ethanol for 2 times, and finally drying and preserving in vacuum;
S2, coating polylactic acid (PLA):
1.5g of polylactic acid is dissolved in 150 mL g of chloroform and fully stirred until the polylactic acid is completely dissolved;
Adding the prepared nano zero-valent iron into the polylactic acid solution, and continuously stirring for 1 hour to form uniform coating;
Removing chloroform by a rotary evaporator at 35 ℃, collecting coated nano zero-valent iron, and drying for later use;
s3, grafting carboxyl groups:
0.75g of acrylic acid and 0.075g of azobisisobutyronitrile are dissolved in 100mL absolute ethanol and fully stirred;
adding nano zero-valent iron coated with polylactic acid into the mixed solution of the acrylic acid and the azodiisobutyronitrile;
The reaction is kept for 12 hours at 60 ℃ to ensure that the acrylic acid can be fully grafted to the surface of the polylactic acid;
after the reaction, the grafted product is washed with ethanol, unreacted monomers and initiator are removed, and the final product is obtained by centrifugal separation and then drying in vacuum.
Example 2: s1, preparing nano zero-valent iron (NZVI):
dissolving 5.0g of ferrous sulfate in 250 mL deionized water, and fully stirring until the ferrous sulfate is completely dissolved;
slowly adding 2.2g of sodium borohydride into the other 250 mL deionized water, and fully stirring until the sodium borohydride is completely dissolved;
slowly dropwise adding the sodium borohydride solution into the ferrous sulfate solution in an inert atmosphere at the dropwise adding rate of 1mL/min;
the reaction was maintained for 15 minutes with stirring to ensure adequate reaction;
Immediately removing unreacted residues through centrifugation or magnetic separation after the reaction, collecting nano zero-valent iron, washing with ethanol for 2 times, and finally drying and preserving in vacuum;
S2, coating polylactic acid (PLA):
1.0g of polylactic acid is dissolved in 100mL of chloroform and fully stirred until the polylactic acid is completely dissolved;
Adding the prepared nano zero-valent iron into the polylactic acid solution, and continuously stirring for 0.5 hour to form uniform coating;
Removing chloroform by a rotary evaporator at 25 ℃, collecting coated nano zero-valent iron, and drying for later use;
s3, grafting carboxyl groups:
Dissolving 0.5g of acrylic acid and 0.05g of azobisisobutyronitrile in 50 mL absolute ethanol, and fully stirring;
adding nano zero-valent iron coated with polylactic acid into the mixed solution of the acrylic acid and the azodiisobutyronitrile;
The reaction is kept for 8 hours at 50 ℃ to ensure that the acrylic acid can be fully grafted to the surface of the polylactic acid;
after the reaction, the grafted product is washed with ethanol, unreacted monomers and initiator are removed, and the final product is obtained by centrifugal separation and then drying in vacuum.
Example 3: s1, preparing nano zero-valent iron (NZVI):
dissolving 10.0g of ferrous sulfate in 250 mL deionized water, and fully stirring until the ferrous sulfate is completely dissolved;
slowly adding 4.4g of sodium borohydride into the other 250 mL deionized water, and fully stirring until the sodium borohydride is completely dissolved;
slowly dropwise adding the sodium borohydride solution into the ferrous sulfate solution in an inert atmosphere, wherein the dropwise adding rate is 5mL/min;
The reaction was maintained for 60 minutes with stirring to ensure adequate reaction;
Immediately removing unreacted residues through centrifugation or magnetic separation after the reaction, collecting nano zero-valent iron, washing 3 times by ethanol, and finally drying and preserving in vacuum;
S2, coating polylactic acid (PLA):
2.0g of polylactic acid is dissolved in 200 mL chloroform and fully stirred until the polylactic acid is completely dissolved;
Adding the prepared nano zero-valent iron into the polylactic acid solution, and continuously stirring for 2 hours to form uniform coating;
Removing chloroform by a rotary evaporator at 45 ℃, collecting coated nano zero-valent iron, and drying for later use;
s3, grafting carboxyl groups:
1.0g of acrylic acid and 0.1g of azobisisobutyronitrile are dissolved in 100 mL absolute ethanol and fully stirred;
adding nano zero-valent iron coated with polylactic acid into the mixed solution of the acrylic acid and the azodiisobutyronitrile;
The reaction is kept for 12 hours at 70 ℃ to ensure that the acrylic acid can be fully grafted to the surface of the polylactic acid;
after the reaction, the grafted product is washed with ethanol, unreacted monomers and initiator are removed, and the final product is obtained by centrifugal separation and then drying in vacuum.
The sources of reagents used in the above examples are:
1. Ferrous sulfate (FeSO 4·7H2 O):
the source is as follows: national medicine group chemical reagent Co., ltd
Purity: analytically pure.
2. Sodium borohydride (NaBH 4):
The source is as follows: sigma-Aldrich
Purity: chromatographic purity.
3. Deionized water:
the source is as follows: the laboratory was self-made and treated with ion exchange resin.
4. Polylactic acid (PLA):
the source is as follows: nature works LLC
Product number: 4040D
Melt index: 14-18 g/10 min.
5. Chloroform (CHCl 3):
the source is as follows: national medicine group chemical reagent Co., ltd
Purity: analytically pure.
6. Acrylic Acid (AA):
the source is as follows: national medicine group chemical reagent Co., ltd
Purity: analytically pure.
7. Azobisisobutyronitrile (AIBN):
The source is as follows: sigma-Aldrich
Purity: chromatographic purity.
8. Absolute ethyl alcohol:
the source is as follows: national medicine group chemical reagent Co., ltd
Purity: analytically pure.
Test example 1
1. Preparation of reagents and samples
Nanocomposite obtained in example 1 (hereinafter referred to as NZVI-PLA): 0.5 g was added to 500 mL g of the contaminated water sample.
Commercial, and untreated NZVI: also 0.5g was added to 500 mL contaminated water samples.
Commercial availability of activated carbon: 0.5 g was added to 500 mL g of the contaminated water sample.
2. Setting experimental conditions
Concentration of contaminants: the initial concentration of lead, copper and chromium is set to be 10 mg/L; the initial concentration of organic contaminants (benzene and methyl blue) was set at 50 mg/L.
And (3) pH adjustment: the pH of the contaminated water sample was adjusted to 5, 7, 9 using 1M HCl or 1M NaOH solutions.
3. Stirring and reacting
Each sample was reacted with stirring at a rate of 250 rpm.
Reaction time: sampling time points were set at 30 minutes, 1 hour, and 2 hours.
4. Sample sampling and processing
Samples were taken at each time point and immediately filtered through a 0.45 μm filter to remove solid particles.
The filtered samples were stored for subsequent analysis at 4 ℃.
5. Analytical assay
Heavy metal determination: the concentration of heavy metals in the filtrate was determined using Atomic Absorption Spectroscopy (AAS).
Determination of organic pollutants: the concentration of organic contaminants in the filtrate is determined using High Performance Liquid Chromatography (HPLC) or ultraviolet-visible spectroscopy (UV-Vis).
6. Data recording and analysis
The contaminant removal rate was calculated for each sample at different time points.
The performance of each sample was compared and the removal efficiency, adsorption capacity and cost effectiveness were assessed.
Benzene removal efficiency:
Methyl blue removal efficiency:
lead removal efficiency:
Copper removal efficiency:
chromium removal efficiency:
Test example 2
1. Experimental materials
The nanocomposite prepared in example 1, which contained a carboxyl grafted layer, was selected for testing its heavy metal ion adsorption efficiency at different concentrations.
2. Preparation of heavy metal ion solution
Heavy metal solutions of chromium and the like with different concentrations are prepared, and the concentrations are classified into three grades of 1 mg/L, 10 mg/L and 100 mg/L.
3. Experimental setup
Batch experiment: the nanocomposite materials with the same mass are respectively added into heavy metal solutions with different concentrations.
Temperature and stirring: experiments were performed at room temperature with a fixed stirring rate to ensure a uniform reaction.
4. Measuring time points
The adsorption efficiency at different time points is monitored by setting 30 minutes, 1 hour and 2 hours as monitoring points.
5. Sample analysis
Sample collection: samples were collected at each time point and solids were removed by filtration or centrifugation.
Heavy metal concentration determination: the concentration of heavy metals in the solution was determined using Atomic Absorption Spectroscopy (AAS).
6. Data recording and analysis
And calculating the removal rate.
The adsorption properties of the materials at different concentrations were analyzed, in particular whether the materials showed enhanced adsorption capacity at high concentrations.
Therefore, by utilizing the carboxyl grafting technology, the material provided by the invention can rapidly increase the complex reaction with heavy metal ions in a high-concentration heavy metal environment, and the adsorption efficiency is obviously improved. High efficiency of treatment performance is maintained even when the concentration of contaminants varies significantly.
The foregoing description of the embodiments of the present application is illustrative, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the improvement of technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (10)
1. A method of preparing a nanocomposite for water treatment, comprising the steps of:
S1, preparing nano zero-valent iron:
Dissolving 5.0-10.0g of ferrous sulfate in 250 mL deionized water, and fully stirring until the ferrous sulfate is completely dissolved;
slowly adding 2.2-4.4g of sodium borohydride into the other 250 mL deionized water, and fully stirring until the sodium borohydride is completely dissolved;
Slowly dropwise adding the sodium borohydride solution into the ferrous sulfate solution in an inert atmosphere at the dropwise adding rate of 1-5mL/min;
maintaining the reaction for 15-60 minutes, and keeping stirring to ensure sufficient reaction;
Immediately removing unreacted residues through centrifugation or magnetic separation after the reaction, collecting nano zero-valent iron, washing with ethanol for 2-3 times, and finally drying and preserving in vacuum;
s2, coating polylactic acid:
Dissolving 1.0g to 2.0g of polylactic acid in 100-200 mL chloroform, and fully stirring until the polylactic acid is completely dissolved;
adding the prepared nano zero-valent iron into the polylactic acid solution, and continuously stirring for 0.5-2 hours to form uniform coating;
Removing chloroform by a rotary evaporator at 25-45 ℃, collecting coated nano zero-valent iron, and drying for later use;
s3, grafting carboxyl groups:
Dissolving 0.5-1.0g of acrylic acid and 0.05-0.1g of azodiisobutyronitrile in 50-100 mL absolute ethyl alcohol, and fully stirring;
adding nano zero-valent iron coated with polylactic acid into the mixed solution of the acrylic acid and the azodiisobutyronitrile;
The reaction is kept for 8 to 12 hours at 50 to 70 ℃ to ensure that the acrylic acid can be fully grafted on the surface of the polylactic acid;
after the reaction, the grafted product is washed with ethanol, unreacted monomers and initiator are removed, and the final product is obtained by centrifugal separation and then drying in vacuum.
2. The method of claim 1, wherein the ferrous sulfate is used in an amount of 7.5 grams.
3. The process according to claim 1, wherein the mass of sodium borohydride used is 3.3 g.
4. The process of claim 1, wherein the reaction time in S1 is 30 minutes.
5. The method according to claim 1, wherein the polylactic acid has a mass of 1.5 g.
6. The method according to claim 1, wherein the volume of chloroform in which polylactic acid is dissolved is 150 mL.
7. The method according to claim 1, wherein the temperature at which chloroform is removed by the rotary evaporator is 35 ℃.
8. The process according to claim 1, wherein the mass of acrylic acid used for grafting the carboxyl group is 0.75 g and the mass of azobisisobutyronitrile is 0.075 g.
9. The process according to claim 1, wherein the grafting reaction is carried out at a temperature of 60℃and a time of 12 hours.
10. Nanocomposite for water treatment, characterized in that it is obtainable by the process according to any one of claims 1 to 9.
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