CN111068626A - Magnetic dithiocarbamic acid modified chitosan microsphere as well as preparation method and application thereof - Google Patents
Magnetic dithiocarbamic acid modified chitosan microsphere as well as preparation method and application thereof Download PDFInfo
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- 229920001661 Chitosan Polymers 0.000 title claims abstract description 81
- 230000005291 magnetic effect Effects 0.000 title claims abstract description 68
- 239000004005 microsphere Substances 0.000 title claims abstract description 59
- DKVNPHBNOWQYFE-UHFFFAOYSA-N carbamodithioic acid Chemical compound NC(S)=S DKVNPHBNOWQYFE-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 239000002351 wastewater Substances 0.000 claims abstract description 15
- QGJOPFRUJISHPQ-UHFFFAOYSA-N Carbon disulfide Chemical compound S=C=S QGJOPFRUJISHPQ-UHFFFAOYSA-N 0.000 claims description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 21
- 239000012990 dithiocarbamate Substances 0.000 claims description 21
- 239000000696 magnetic material Substances 0.000 claims description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 17
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 238000005406 washing Methods 0.000 claims description 11
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- 239000012153 distilled water Substances 0.000 claims description 9
- 150000001875 compounds Chemical class 0.000 claims description 8
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 8
- 239000011790 ferrous sulphate Substances 0.000 claims description 6
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 6
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 6
- 238000000926 separation method Methods 0.000 claims description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 5
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- 238000004132 cross linking Methods 0.000 claims description 4
- 239000000725 suspension Substances 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- QGJOPFRUJISHPQ-NJFSPNSNSA-N carbon disulfide-14c Chemical compound S=[14C]=S QGJOPFRUJISHPQ-NJFSPNSNSA-N 0.000 claims description 3
- 238000004945 emulsification Methods 0.000 claims description 3
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 230000003472 neutralizing effect Effects 0.000 claims description 3
- 239000002202 Polyethylene glycol Substances 0.000 claims description 2
- 230000032683 aging Effects 0.000 claims description 2
- 229960002089 ferrous chloride Drugs 0.000 claims description 2
- FBAFATDZDUQKNH-UHFFFAOYSA-M iron chloride Chemical compound [Cl-].[Fe] FBAFATDZDUQKNH-UHFFFAOYSA-M 0.000 claims description 2
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 2
- XBDUTCVQJHJTQZ-UHFFFAOYSA-L iron(2+) sulfate monohydrate Chemical compound O.[Fe+2].[O-]S([O-])(=O)=O XBDUTCVQJHJTQZ-UHFFFAOYSA-L 0.000 claims description 2
- 229920001223 polyethylene glycol Polymers 0.000 claims description 2
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims 2
- 238000001179 sorption measurement Methods 0.000 abstract description 22
- 229910021645 metal ion Inorganic materials 0.000 abstract description 6
- 230000002378 acidificating effect Effects 0.000 abstract description 4
- 239000011651 chromium Substances 0.000 description 22
- 239000000243 solution Substances 0.000 description 20
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 229910001385 heavy metal Inorganic materials 0.000 description 8
- 239000003463 adsorbent Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 241000282414 Homo sapiens Species 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 description 3
- 239000012670 alkaline solution Substances 0.000 description 3
- 125000004429 atom Chemical group 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- NWGKJDSIEKMTRX-AAZCQSIUSA-N Sorbitan monooleate Chemical compound CCCCCCCC\C=C/CCCCCCCC(=O)OC[C@@H](O)[C@H]1OC[C@H](O)[C@H]1O NWGKJDSIEKMTRX-AAZCQSIUSA-N 0.000 description 2
- 238000010170 biological method Methods 0.000 description 2
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- 229910000358 iron sulfate Inorganic materials 0.000 description 2
- 229940057995 liquid paraffin Drugs 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 description 2
- 239000006228 supernatant Substances 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 241001465754 Metazoa Species 0.000 description 1
- 229920001030 Polyethylene Glycol 4000 Polymers 0.000 description 1
- 125000003172 aldehyde group Chemical group 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- -1 amino polysaccharide Chemical class 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- WURBFLDFSFBTLW-UHFFFAOYSA-N benzil Chemical group C=1C=CC=CC=1C(=O)C(=O)C1=CC=CC=C1 WURBFLDFSFBTLW-UHFFFAOYSA-N 0.000 description 1
- 238000006065 biodegradation reaction Methods 0.000 description 1
- 239000012620 biological material Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000009388 chemical precipitation Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000850 deacetylating effect Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
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- 231100000053 low toxicity Toxicity 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052603 melanterite Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 230000005298 paramagnetic effect Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229940057838 polyethylene glycol 4000 Drugs 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- PXQLVRUNWNTZOS-UHFFFAOYSA-N sulfanyl Chemical class [SH] PXQLVRUNWNTZOS-UHFFFAOYSA-N 0.000 description 1
- 125000004434 sulfur atom Chemical group 0.000 description 1
- 238000009210 therapy by ultrasound Methods 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 238000003911 water pollution Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
- B01J20/24—Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
- B01J20/28009—Magnetic properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
- B01J20/28016—Particle form
- B01J20/28019—Spherical, ellipsoidal or cylindrical
-
- 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
- C02F1/286—Treatment of water, waste water, or sewage by sorption using natural organic sorbents or derivatives thereof
-
- 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
- C02F2101/20—Heavy metals or heavy metal compounds
- C02F2101/22—Chromium or chromium compounds, e.g. chromates
-
- 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
- Y02W10/30—Wastewater or sewage treatment systems using renewable energies
- Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy
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- Chemical & Material Sciences (AREA)
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- Analytical Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The invention discloses a magnetic dithiocarbamic acid modified chitosan microsphere and a preparation method thereof. By modifying the chitosan magnetic microspheres with dithiocarbamic acid, the stability of the chitosan magnetic microspheres in an acidic medium can be increased, and meanwhile, a large number of S coordination atoms in the introduced sulfydryl can form stable complexes with metal ions, so that the adsorption performance on the metal ions is improved, and especially the adsorption capacity on Cr (VI) in wastewater is increased.
Description
Technical Field
The invention belongs to the field of environmental engineering application, and particularly relates to a magnetic dithiocarbamate modified chitosan microsphere and a preparation method thereof, and application of the magnetic dithiocarbamate modified chitosan microsphere in adsorption of Cr (VI) in wastewater.
Background
Water is a source of life and an indispensable natural resource for human beings and all living beings to live and develop. However, in recent years, with the rapid development of the global industrial agriculture and the scientific and technological progress, the water demand is increasing, and the emission of a large amount of waste water is corresponding to the increase, and the problem of the increasing serious water pollution is just one of the important challenges facing the human development.
Chromium is one of elements widely existing in nature, and chromium and compounds thereof are widely applied to industries such as electroplating, tanning, namely coating and the like, so that a large amount of chromium-containing wastewater can not be generated in the production process. The existing form of chromium is mainly Cr (III) and Cr (VI), wherein Cr (VI) is one of the most common heavy metal pollutants, has strong oxidizability and toxicity, can be transferred along with rivers or underground water, further pollutes water and soil resources, harms the living environment of animals and plants, further influences human life, and is harmful to human health.
The Cr (VI) compound can not be naturally degraded, and the main technologies for treating the Cr (VI) wastewater at present comprise a chemical precipitation method, an ion exchange method, a biological method, an adsorption method and a biological method. The adsorption method is to adsorb heavy metal substances in the wastewater on the surface by using a solid adsorbent and then resolve the solute so as to achieve the purposes of separating and enriching metals. The adsorption method has the characteristics of simple equipment, convenient operation, low cost, no secondary pollution, good treatment effect and the like, and has application value in a method for quickly treating the wastewater containing Cr (VI). At present, the technical core of treating the wastewater containing Cr (VI) by using an adsorption method is to develop an adsorption material with high adsorption efficiency and low cost, which can effectively adsorb Cr (VI) elements in the wastewater and reduce the wastewater treatment cost.
The chitosan is a natural alkali obtained by deacetylating chitinThe amino polysaccharide is a natural high molecular biological material with good biocompatibility, easy biodegradation, no toxicity, low cost and easy obtaining. The chitosan molecule contains a large amount of amino and hydroxyl, and the groups have lone pair electrons and can form stable chelate with heavy metal ions. However, the chitosan has poor water solubility, is only dissolved in dilute acid solution, and has-NH at the C2 position of the chitosan under the acidic condition2Is easy to form-NH3 +And the adsorption of heavy metal is not facilitated, so that the adsorption effect is poor, and the application of the heavy metal is limited. Meanwhile, the method of using only chitosan as the heavy metal adsorbent has the disadvantages of low recovery rate of the adsorbent, unfavorable reuse of the adsorbent and increased treatment cost.
The dithiocarbamic acid contains S, N coordination atoms and can form a chelate with a high stability constant with a plurality of heavy metal ions. Therefore, the invention obtains the dithiocarbamic acid modified chitosan microsphere by reacting carbon disulfide with the chitosan microsphere under the alkaline condition. By modifying the chitosan magnetic microspheres with dithiocarbamic acid, the stability of the chitosan magnetic microspheres in an acidic medium can be increased, and meanwhile, a large number of S coordination atoms in the introduced sulfydryl can form stable complexes with metal ions, so that the adsorption performance of chitosan on the metal ions is improved.
The magnetic ferroferric oxide nano-particles have good compatibility and paramagnetic property, low toxicity and easy separation from a liquid phase. The method comprises the steps of preparing magnetic chitosan microspheres by taking chitosan as a raw material and ferroferric oxide nanoparticles as magnetic cores, modifying the magnetic chitosan microspheres by taking carbon disulfide as a modifier to prepare the magnetic dithiocarbamate modified chitosan microspheres, and applying the magnetic dithiocarbamate modified chitosan microspheres to adsorption treatment of Cr (VI) in wastewater.
Disclosure of Invention
The invention aims to provide a magnetic dithiocarbamate modified chitosan microsphere and a preparation method thereof, and the invention also aims to provide an application of the magnetic dithiocarbamate modified chitosan microsphere in adsorption of Cr (VI) in wastewater.
The purpose of the invention is realized by the following technical scheme:
in a first aspect, the invention provides a preparation method of magnetic dithiocarbamate modified chitosan microspheres, which comprises the following steps:
(1) preparation of water-based Fe3O4Nano magnetic material: dissolving iron-containing compound in polyethylene glycol solution, dripping concentrated ammonia water until pH is not less than 10, aging for 1-2 hr, neutralizing with acid until pH is 7.0, and separating with magnetic field to obtain water-based Fe3O4A nano-magnetic material;
(2) preparing magnetic chitosan microspheres: adding the Fe prepared in the step (1) into a chitosan solution3O4The nano magnetic material is ultrasonically and uniformly mixed, and the magnetic chitosan microspheres are prepared by an emulsification crosslinking method;
(3) preparing magnetic dithiocarbamic acid modified chitosan microspheres: suspending the magnetic chitosan microspheres prepared in the step (2) in methanol to obtain suspension with the concentration of 10-30mg/mL, ultrasonically mixing the suspension uniformly, adding carbon disulfide, ultrasonically reacting for 0.5-2h, and carrying out magnetic field separation to obtain the magnetic dithiocarbamic acid modified chitosan microspheres.
The iron-containing compound in step (1) includes, but is not limited to, hydrated iron chloride (FeCl)3·6H2O), ferrous chloride hydrate (FeCl)2·4H2O), iron sulfate hydrate (Fe)2(SO4)3·9H2O), hydrated ferrous sulfate (FeSO)4·7H2O) or a combination of two or more thereof.
In the most preferred embodiment of the present invention, the iron-containing compound is a combination of hydrated iron sulfate and hydrated ferrous sulfate, and the mass ratio of the hydrated iron sulfate to the hydrated ferrous sulfate is 4-10: 1.
Preferably, the acid used for adjusting the pH of the system in step (1) is selected from acetic acid or hydrochloric acid, and acetic acid with a concentration of 25% by mass is used in the present invention.
Preferably, the magnetic field separation in the step (1) is specifically to place the reaction system right above the magnet and stand for 1-3h, pour the upper liquid and scum, wash the microspheres with distilled water for 3-5 times to obtain the black and bright water-based Fe3O4A nanomagnetic material.
Preferably, the chitosan solution in step (2) is a solution of chitosan dissolved in 2.5% by mass of acetic acid, the chitosan and Fe3O4Adding the nano magnetic material in a mass ratio of 1-5: 1; more preferably, chitosan is mixed with Fe3O4Adding the nano magnetic material in a mass ratio of 1-3: 1; in the most preferred embodiment of the invention, chitosan is combined with Fe3O4The mass ratio of the added nano magnetic material is 3: 1.
The emulsion crosslinking method specifically comprises the following steps: chitosan and Fe3O4Adding the mixed solution of the nano magnetic material into liquid paraffin containing 3 percent of emulsifier span-80 for a plurality of times in a small amount, stirring and emulsifying at the constant temperature of 35 ℃ at the rotating speed of 3000 r/min, adding glutaraldehyde solution with the mass percentage concentration of 25 percent for solidification after the completion, and separating by a magnetic field to obtain a target product.
Preferably, the step (2) further comprises washing the surface of the microsphere with diethyl ether for 3-5 times by magnetic filtration, washing with distilled water for 3-5 times, and drying in a vacuum oven at 60 ℃ for 1-3 h.
Preferably, the carbon disulfide is added in the step (3) and then ultrasonic reaction is carried out for 0.5-1h, most preferably ultrasonic reaction is carried out for 1h, and the volume percent of the added carbon disulfide is 6%.
Preferably, the step (3) further comprises washing the surface of the microsphere of the product with absolute ethyl alcohol by using a magnetic filtration mode for 3 to 5 times, then washing with distilled water for 3 to 5 times, and then drying in a vacuum oven at 60 ℃ for 1 to 3 hours.
In a second aspect, the invention provides a magnetic dithiocarbamate modified chitosan microsphere, which is prepared by the method.
In a third aspect, the invention also provides application of the magnetic dithiocarbamate modified chitosan microspheres in adsorption of Cr (VI) in wastewater.
Preferably, the concentration of Cr (VI) in the wastewater is 100-200 mg/L.
After the magnetic dithiocarbamate modified chitosan microspheres are used as an adsorbent to adsorb heavy metal ions, the magnetic field separation is adopted, and then alkaline solution is used for soaking and/or washing desorption, so that the magnetic dithiocarbamate modified chitosan microspheres can be repeatedly utilized.
Preferably, the alkaline solution is selected from ammonia water with volume fraction of 10-20% or sodium hydroxide solution with concentration of 0.1-0.5%.
In a preferred embodiment of the present invention, the alkaline solution is 10% by volume of aqueous ammonia.
The magnetic dithiocarbamate modified chitosan microsphere prepared by the invention can be repeatedly utilized for 3-5 times, and preferably 3 times.
The invention has the beneficial effects that: under the catalytic action of sodium hydroxide, the active amino on the macromolecular chain of chitosan and carbon disulfide are subjected to heterogeneous reaction, and the hydrogen atom on the amino is substituted to generate the dithiocarbamate of chitosan. The carbon disulfide introduces dithiocarbamic acid groups into the molecular structure of the chitosan, and the mercapto (-SH) S atom on the dithiocarbamic acid group has a ratio of-NH2The N, O coordination atom on the-OH has stronger coordination capacity with metal ions, and thus has stronger adsorption capacity on the metal ions. Meanwhile, the cross-linking reaction is carried out by the addition elimination reaction of amino in chitosan molecules and aldehyde groups of glutaraldehyde, and linear chitosan molecules are cross-linked into net-shaped macromolecules, so that the problem of easy dissolution and loss of chitosan in an acidic medium is enhanced. Magnetic Fe3O4The nano-particles have good compatibility and magnetic responsiveness, and after wastewater treatment, the magnetic Fe3O4The dithiocarbamate modified chitosan microspheres loaded by the nano material can be quickly separated from a treated water body, and the separated magnetic dithiocarbamate modified chitosan microspheres can be regenerated and recycled.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
S1: adding 5g of polyethylene glycol4000 parts by mass of the mixture is dissolved in 100mL of distilled water, and the mass ratio of the mixture is 1: 4 adding FeSO4·7H2O and Fe2(SO4)3·9H2Fully dissolving 11.12g of O, dripping concentrated ammonia water under the conditions of stirring and 50 ℃ heat preservation until the pH value is more than or equal to 10.0, continuing curing reaction for 2 hours, neutralizing the solution with acetic acid with the mass percent concentration of 25% until the pH value is 7.0, separating the solution by a magnetic field, pouring the upper layer liquid and floating slag, and washing the solution with distilled water to remove impurities to obtain the blackish and bright water-based Fe3O4A nano-magnetic material;
s2: accurately weighing 0.3g of chitosan, dissolving the chitosan in 10mL of acetic acid solution with the mass percentage of 2.5%, and mixing the chitosan: fe3O4Nano-magnetic material 3:1, 0.1g of Fe prepared in step S1 was added3O4Performing ultrasonic treatment on the nano magnetic material for 5-10min to uniformly mix;
s3: adding 5g of mixed solution into 60mL of liquid paraffin containing 3% of emulsifier span-80 in a small amount for multiple times, stirring and emulsifying at constant temperature of 35 ℃ at a rotating speed of 3000 r/min for 1h, adding 0.15mL of glutaraldehyde solution with the mass percentage concentration of 25% after emulsification is finished, solidifying for 6h, transferring reactants into a small beaker, layering by using a magnetic field, removing supernatant, washing organic volume on the surface of the microsphere by using ether in a small amount for 3 times, washing for three times by using distilled water, carrying out magnetic filtration, and drying the product in a vacuum oven at 60 ℃ to obtain the magnetic chitosan microsphere;
s4: weighing 1g of magnetic chitosan microspheres, suspending the magnetic chitosan microspheres in 50mL of methanol, dropwise adding 50mL of 8 mass percent sodium hydroxide solution under stirring, standing and defoaming after ultrasonic homogenization, adding 6 volume percent carbon disulfide, carrying out ultrasonic reaction for 1h, separating a product by using a magnetic field after the reaction is finished, discarding a supernatant, washing the product by using absolute ethyl alcohol and distilled water for three times respectively, carrying out magnetic filtration, and drying the product in a vacuum oven at 60 ℃ to obtain the magnetic dithiocarbamic acid modified chitosan microspheres.
Example 2
The preparation method and the preparation raw materials are the same as example 1, except that the ultrasonic reaction is carried out for 0.5h after the carbon disulfide is added in the step S4.
Example 3
The preparation method and the preparation raw materials are the same as example 1, and the difference is only that the chitosan in the step S2: fe3O4Nano magnetic material 1: 1, addition of Fe3O4The nano-magnetic material was 0.3 g.
Comparative example 1
The preparation method and the preparation raw material are the same as example 1, except that carbon disulfide is not added in step S4.
Effect example 1
Purpose of the experiment: detecting the capacity of the magnetic dithiocarbamate modified chitosan microspheres prepared by the invention for adsorbing Cr (VI);
the experimental method comprises the following steps: adding 100mL of potassium dichromate solution with Cr (VI) concentration of 100mg/L into a 250mL conical flask with a plug, adjusting the pH to 5.0, respectively adding 100mg of the magnetic dithiocarbamate modified chitosan microspheres prepared in examples 1-3 and the magnetic chitosan microspheres prepared in comparative example 1 into the solution, putting the conical flask with the plug into a constant-temperature oscillator, adsorbing at 25 ℃ under 180 r/min, sampling at 60min, determining the Cr (VI) concentration by using a dibenzoyl dihydrazide spectrophotometry specified in the national water quality monitoring standard analysis method, and calculating the adsorption capacity of the adsorbent;
the experimental results are as follows: the results of the experiments are shown in the following table.
TABLE 1 adsorption Capacity of magnetic dithiocarbamate modified Chitosan microspheres for Cr (VI)
The chitosan microspheres prepared in example 1 are dithiocarbamic acid modified magnetic chitosan microspheres, the magnetic chitosan microspheres prepared in comparative example 1 are not modified, the adsorption capacity (585mg/g) of the microspheres in example 1 is more than 4 times of the adsorption capacity (142.6mg/g) of the microspheres in comparative example 1, and the adsorption capacity of the magnetic chitosan microspheres modified by dithiocarbamic acid to water (Cr (VI) is proved to beAnd (4) the improvement is remarkable. Comparison of the adsorption capacity data of example 1 with that of example 2 shows that the effect of 1 hour of ultrasonic reaction after addition of carbon disulfide is better than the effect of 0.5 hour of ultrasonic reaction. Comparison of the data in example 1 and example 3 shows that chitosan and Fe are mixed during the preparation of magnetic chitosan microspheres3O4The optimal mass ratio of the nano magnetic material is 3: 1.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A preparation method of magnetic dithiocarbamate modified chitosan microspheres comprises the following steps:
(1) preparation of water-based Fe3O4Nano magnetic material: dissolving iron-containing compound in polyethylene glycol solution, dripping concentrated ammonia water until pH is not less than 10, aging for 1-2 hr, neutralizing with acid until pH is 7.0, and separating with magnetic field to obtain water-based Fe3O4A nano-magnetic material;
(2) preparing magnetic chitosan microspheres: adding the Fe prepared in the step (1) into a chitosan solution3O4The nano magnetic material is ultrasonically and uniformly mixed, and the magnetic chitosan microspheres are prepared by an emulsification crosslinking method;
(3) preparing magnetic dithiocarbamic acid modified chitosan microspheres: suspending the magnetic chitosan microspheres prepared in the step (2) in methanol to obtain suspension with the concentration of 10-30mg/mL, ultrasonically mixing the suspension uniformly, adding carbon disulfide, ultrasonically reacting for 0.5-2h, and carrying out magnetic field separation to obtain the magnetic dithiocarbamic acid modified chitosan microspheres.
2. The method according to claim 1, wherein the step (1) comprisesIron compounds include, but are not limited to, hydrated iron chloride (FeCl)3·6H2O), ferrous chloride hydrate (FeCl)2·4H2O), iron sulfate hydrate (Fe)2(SO4)3·9H2O), hydrated ferrous sulfate (FeSO)4·7H2O) or a combination of two or more thereof.
3. The preparation method of claim 2, wherein the iron-containing compound is a combination of hydrated ferric sulfate and hydrated ferrous sulfate, the mass ratio of the hydrated ferric sulfate to the hydrated ferrous sulfate is 4-10:1, and the acid used for adjusting the pH of the system in the step (1) is selected from acetic acid or hydrochloric acid.
4. The preparation method according to claim 1, wherein the magnetic field separation in the step (1) is specifically that the reaction system is placed right above the magnet and stands for 1-3h, the upper liquid and scum are poured out, and the microspheres are washed 3-5 times by distilled water to obtain the water-based Fe3O4A nanomagnetic material.
5. The method according to claim 1, wherein the chitosan solution in the step (2) is a solution of chitosan dissolved in 2.5% by mass of acetic acid, the chitosan being in combination with Fe3O4Adding the nano magnetic material in a mass ratio of 1-5: 1; and (4) adding carbon disulfide in the step (3) and then carrying out ultrasonic reaction for 0.5-1 h.
6. The method according to claim 5, wherein the chitosan and Fe are used in the step (2)3O4Adding the nano magnetic material in a mass ratio of 1-3: 1; and (4) carrying out ultrasonic reaction for 1h after adding carbon disulfide in the step (3), wherein the volume percentage of the added carbon disulfide is 6%.
7. The preparation method of claim 1, wherein the steps (2) and (3) further comprise washing the surface of the microspheres with absolute ethanol for 3-5 times by magnetic filtration, washing with distilled water for 3-5 times, and drying in a vacuum oven at 60 ℃ for 1-3 h.
8. A magnetic dithiocarbamate modified chitosan microsphere, prepared by the method of any one of claims 1 to 7.
9. The use of the magnetic dithiocarbamate modified chitosan microsphere of claim 8 for adsorbing Cr (VI) in wastewater.
10. The use as claimed in claim 9, wherein the concentration of Cr (VI) in the wastewater is 100-200 mg/L.
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