CN114177892B - Carbon nano tube composite adsorbent and preparation method thereof - Google Patents
Carbon nano tube composite adsorbent and preparation method thereof Download PDFInfo
- Publication number
- CN114177892B CN114177892B CN202111498976.2A CN202111498976A CN114177892B CN 114177892 B CN114177892 B CN 114177892B CN 202111498976 A CN202111498976 A CN 202111498976A CN 114177892 B CN114177892 B CN 114177892B
- Authority
- CN
- China
- Prior art keywords
- adsorption
- wscc
- wall
- carbon nano
- nano tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 52
- 239000003463 adsorbent Substances 0.000 title claims abstract description 41
- 239000002131 composite material Substances 0.000 title claims abstract description 31
- 239000002041 carbon nanotube Substances 0.000 title claims abstract description 26
- 229910021393 carbon nanotube Inorganic materials 0.000 title claims abstract description 26
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 238000001179 sorption measurement Methods 0.000 claims abstract description 155
- 239000002048 multi walled nanotube Substances 0.000 claims abstract description 76
- 229920001661 Chitosan Polymers 0.000 claims abstract description 59
- 239000002109 single walled nanotube Substances 0.000 claims abstract description 47
- 239000002253 acid Substances 0.000 claims abstract description 29
- 230000003647 oxidation Effects 0.000 claims abstract description 22
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 22
- 239000011246 composite particle Substances 0.000 claims abstract description 16
- 150000002500 ions Chemical class 0.000 claims abstract description 13
- 239000000243 solution Substances 0.000 claims description 60
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 23
- 238000001035 drying Methods 0.000 claims description 16
- 239000007787 solid Substances 0.000 claims description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 238000000926 separation method Methods 0.000 claims description 11
- 239000002904 solvent Substances 0.000 claims description 11
- FOCAUTSVDIKZOP-UHFFFAOYSA-N chloroacetic acid Chemical compound OC(=O)CCl FOCAUTSVDIKZOP-UHFFFAOYSA-N 0.000 claims description 10
- 229940106681 chloroacetic acid Drugs 0.000 claims description 10
- 239000006185 dispersion Substances 0.000 claims description 10
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 8
- 229910017604 nitric acid Inorganic materials 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 7
- 238000001132 ultrasonic dispersion Methods 0.000 claims description 5
- 238000005119 centrifugation Methods 0.000 claims description 4
- 238000005406 washing Methods 0.000 claims description 4
- 239000011248 coating agent Substances 0.000 claims description 3
- 238000000576 coating method Methods 0.000 claims description 3
- 230000015556 catabolic process Effects 0.000 claims description 2
- 238000006731 degradation reaction Methods 0.000 claims description 2
- 239000011259 mixed solution Substances 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000010992 reflux Methods 0.000 claims description 2
- 230000008961 swelling Effects 0.000 claims description 2
- 238000009210 therapy by ultrasound Methods 0.000 claims description 2
- 238000002474 experimental method Methods 0.000 abstract description 16
- 239000002114 nanocomposite Substances 0.000 abstract description 9
- 229910021645 metal ion Inorganic materials 0.000 abstract description 8
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 abstract description 5
- 239000000463 material Substances 0.000 abstract description 5
- 125000003277 amino group Chemical group 0.000 abstract description 3
- 238000005341 cation exchange Methods 0.000 abstract description 3
- 125000000524 functional group Chemical group 0.000 abstract description 3
- 239000002270 dispersing agent Substances 0.000 abstract description 2
- 238000006116 polymerization reaction Methods 0.000 abstract description 2
- 230000001737 promoting effect Effects 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 49
- 230000000694 effects Effects 0.000 description 17
- 238000000034 method Methods 0.000 description 15
- 230000001965 increasing effect Effects 0.000 description 11
- 230000008569 process Effects 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 230000007547 defect Effects 0.000 description 9
- 235000019441 ethanol Nutrition 0.000 description 9
- 239000007864 aqueous solution Substances 0.000 description 8
- 239000012153 distilled water Substances 0.000 description 8
- 239000010410 layer Substances 0.000 description 8
- 230000007246 mechanism Effects 0.000 description 8
- 229910052799 carbon Inorganic materials 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 238000001914 filtration Methods 0.000 description 6
- 229910001385 heavy metal Inorganic materials 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 5
- 238000001237 Raman spectrum Methods 0.000 description 4
- 238000003917 TEM image Methods 0.000 description 4
- 238000010306 acid treatment Methods 0.000 description 4
- -1 carboxymethy l Chemical class 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 238000002329 infrared spectrum Methods 0.000 description 4
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000002052 molecular layer Substances 0.000 description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 description 3
- 239000002356 single layer Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 229960000583 acetic acid Drugs 0.000 description 2
- 239000003929 acidic solution Substances 0.000 description 2
- 229910003481 amorphous carbon Inorganic materials 0.000 description 2
- LSQZJLSUYDQPKJ-NJBDSQKTSA-N amoxicillin Chemical compound C1([C@@H](N)C(=O)N[C@H]2[C@H]3SC([C@@H](N3C2=O)C(O)=O)(C)C)=CC=C(O)C=C1 LSQZJLSUYDQPKJ-NJBDSQKTSA-N 0.000 description 2
- 229960003022 amoxicillin Drugs 0.000 description 2
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 2
- 239000012043 crude product Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000009881 electrostatic interaction Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 239000012362 glacial acetic acid Substances 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- LSQZJLSUYDQPKJ-UHFFFAOYSA-N p-Hydroxyampicillin Natural products O=C1N2C(C(O)=O)C(C)(C)SC2C1NC(=O)C(N)C1=CC=C(O)C=C1 LSQZJLSUYDQPKJ-UHFFFAOYSA-N 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000003911 water pollution Methods 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 239000005725 8-Hydroxyquinoline Substances 0.000 description 1
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 1
- 238000001069 Raman spectroscopy Methods 0.000 description 1
- 238000005411 Van der Waals force Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 239000002156 adsorbate Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000001476 alcoholic effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000012620 biological material Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 125000002843 carboxylic acid group Chemical group 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 230000009918 complex formation Effects 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 150000004696 coordination complex Chemical class 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 230000006196 deacetylation Effects 0.000 description 1
- 238000003381 deacetylation reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000010537 deprotonation reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000000499 gel Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000017 hydrogel Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- RLJMLMKIBZAXJO-UHFFFAOYSA-N lead nitrate Chemical compound [O-][N+](=O)O[Pb]O[N+]([O-])=O RLJMLMKIBZAXJO-UHFFFAOYSA-N 0.000 description 1
- 238000003760 magnetic stirring Methods 0.000 description 1
- 238000005374 membrane filtration Methods 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
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 239000002071 nanotube Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229960003540 oxyquinoline Drugs 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000005588 protonation Effects 0.000 description 1
- MCJGNVYPOGVAJF-UHFFFAOYSA-N quinolin-8-ol Chemical compound C1=CN=C2C(O)=CC=CC2=C1 MCJGNVYPOGVAJF-UHFFFAOYSA-N 0.000 description 1
- 238000009790 rate-determining step (RDS) Methods 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229940083608 sodium hydroxide Drugs 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 238000000527 sonication Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- 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
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
- B01J20/205—Carbon nanostructures, e.g. nanotubes, nanohorns, nanocones, nanoballs
-
- 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
-
- 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
- C02F1/288—Treatment of water, waste water, or sewage by sorption using composite sorbents, e.g. coated, impregnated, multi-layered
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Analytical Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Nanotechnology (AREA)
- Inorganic Chemistry (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
The invention discloses a carbon nano tube composite adsorbent and a preparation method thereof, wherein the carbon nano tube composite adsorbent comprises composite particles formed by wrapping O-carboxymethyl chitosan on the surface of a multi-wall or single-wall carbon nano tube subjected to acid oxidation treatment, the O-carboxymethyl chitosan is taken as a dispersing agent to promote the dispersibility of the multi-wall or single-wall carbon nano tube in a solution, the occurrence of polymerization phenomenon is avoided, in an adsorption experiment, the inner layer of Pb (II) ions on the adsorbent is adsorbed to form a metal-N complex between nano composite materials, negative charges such as-COOH, -OH and other functional groups on the side wall of the multi-wall carbon nano tube provide electron pairs for metal ions, thereby promoting cation exchange, and the amino groups of the O-carboxymethyl chitosan synergistically promote the adsorption capacity of the carbon nano tube, and the adsorption capacity of Pb (II) ions can reach more than 98%.
Description
Technical Field
The invention relates to the technical field of adsorption, in particular to a carbon nano tube composite adsorbent and a preparation method thereof.
Background
The emission of toxic metals in the environment can cause water pollution. Water pollution is a global problem affecting millions of people's living parties worldwide and poses a serious threat to human health. Pb (II) is one of the most cancerogenic heavy metals, and enters the food chain through the polluted water body, thereby threatening the safety of the whole biosphere. The environmental protection agency prescribes a maximum allowable exposure value of Pb (II) in drinking water of 0.015mg L -1. Therefore, it is important to study how to effectively remove Pb (II) in wastewater.
The method for removing heavy metal ions in water comprises the following steps: coprecipitation, membrane filtration, reverse osmosis, adsorption, etc. Among these methods, the adsorption method has the advantages of simple operation, low cost, good effect and the like. Commonly used adsorbents are activated carbon, biological materials, hydrogels, silica gels, nanocomposites and the like. However, these adsorbents have disadvantages such as low specific surface area and poor adsorptivity. At present, research on multi-wall carbon nanotubes (MWCNTs) is a hot spot field, the MWCNTs are hollow tubes formed by curling multi-layer graphite sheets, have larger specific surface area and show strong adsorption effect. Therefore, the MWCNTs can adsorb heavy metal ions in water, thereby achieving the purpose of purifying water quality. The defects are that: the MWCNTs have strong van der Waals acting force between the pipes, so that the MWCNTs are easy to agglomerate, the dispersibility in water is poor, the effective specific surface area of the MWCNTs is reduced, and the adsorption efficiency of the MWCNTs on certain substances in water is reduced.
For this purpose FARHADIAN N, et al, envi ronmental technology,2018,39 (17): 2231-2242, use multi-walled carbon nanotubes to remove amoxicillin from water. In order to improve the adsorption capacity of the adsorbent, surface modified carbon nano tubes are adopted, 8-hydroxyquinoline and carboxyl are selected as modification groups to carry out surface modification on MWCNTs, and the influence of important parameters related to adsorption quantity such as pH, amoxicillin initial concentration, adsorption equilibrium time and the like on adsorption is studied.
P, et al, adsorption Science & Technology,2017,35 (9-10): 806-816, theoretical discussion of the adsorption properties of oxidized multiwall carbon nanotubes on phenol in water from adsorption equilibrium, adsorption heat effect, adsorption kinetics, etc.
Shah F. Et al ANALYTICAL LETTERS,2020,53 (10): 1566-1579, modified MWCNTs with glycerol plasticised starch/citric acid, examined for their adsorption capacity for Pb (II). The adsorbent showed good stability with an analyte recovery of 97%.
Khan M.et al, journal of Molecu lar Liquids,2016,224:639-647 synthesized 1- (2-pyridinazo) -2-naphthol impregnated silica coated magnetic multi-walled carbon nanotubes, studied the adsorption of Pb (II) and Co (II) in water, with lead and cobalt detection limits of 1.76 μg L -1、0.55μg﹒L-1, respectively.
Chitosan is a low-cost environment-friendly biopolymer and is characterized by containing a large amount of amino groups and hydroxyl groups, which is particularly important in removing pollutants from aqueous solutions. The lone pair electrons of the chitosan nitrogen atoms provide good prospects for the application of the chitosan nitrogen atoms in heavy metal adsorption, and some researches show that when chitosan is loaded on the multi-wall carbon nano tube, the composite material has high adsorption capacity and good reusability for heavy metal removal. However, the difficulty is that the combination mode of chitosan and multi-wall nanotubes, the main and secondary adsorption mechanism of the combined product, the coordination relationship and the like are not clear. The patent application number is 2020105577222, which is named as a cross-linked chitosan-multi-carbon nano tube composite material and an application thereof discloses a scheme, the combination mode is complex, after the combination, the cross-linked chitosan is used as main chelate metal ions, and the carbon nano tube is used for adsorbing organic small molecular compounds. In the patent application number 2014105640540, the scheme disclosed in the preparation method of the crosslinked chitosan adsorbent with the composite carbon nano tube takes epichlorohydrin as a crosslinking agent, and the chitosan metal complex and the carbon nano tube are compounded to form the adsorbent, so that the adsorption mechanism and the adsorption effect are not clearly described, and the defect of complex bonding mode exists.
Disclosure of Invention
In order to solve at least one technical defect, the invention provides the following technical scheme:
the application discloses a carbon nano tube composite adsorbent, which comprises composite particles formed by wrapping O-carboxymethyl chitosan on the surface of multi-wall or single-wall carbon nano tubes subjected to acid oxidation treatment.
The inventor selects a combination mode that O-carboxymethyl chitosan is wrapped on a multi-wall or single-wall carbon nano tube subjected to acid oxidation treatment through a large number of experiments, takes O-carboxymethyl chitosan as a dispersing agent to promote the dispersibility of the multi-wall or single-wall carbon nano tube in a solution, and avoids polymerization phenomenon, and finds that the adsorbent follows a two-level kinetic adsorption isothermal line, langmu I r and Freund's ich adsorption isotherm in adsorption experiments, which shows that Pb (I) ions form a metal-N complex between nano composite materials when the inner layer on the adsorbent is adsorbed, negative charges on the side wall of the multi-wall carbon nano tube, such as functional groups of COOH and-OH, provide electron pairs for the metal ions, thereby promoting cation exchange, amino groups of the O-carboxymethyl chitosan synergistically promote the adsorption capacity of the carbon nano tube, and the adsorption of Pb (I) ions can reach more than 98 percent, and the adsorption mechanism has obvious difference from that disclosed in the patent application number 2020105577222.
Further, mixing the O-carboxymethyl chitosan and the multiwall carbon nano tube subjected to acid oxidation treatment in a solvent at a mass ratio of 0.3-0.7, and drying solid components obtained by centrifugal separation to obtain composite particles;
the O-carboxymethyl chitosan and the single-wall carbon nano tube treated by acid oxidation are mixed in a solvent under the mass ratio of 0.003-0.007, and the solid components separated by centrifugation are dried to obtain the composite particles.
Furthermore, the O-carboxymethyl chitosan is prepared by reacting chitosan with chloroacetic acid in an alkaline medium, and the O-position of the chitosan is introduced by reacting the chitosan with the chloroacetic acid in a low-temperature alkaline medium.
Further, oxidation treatment of multi-wall or single-wall carbon nanotubes with nitric acid is also a common treatment method.
The application discloses a preparation method of a carbon nano tube composite adsorbent, which comprises the steps of placing O-carboxymethyl chitosan and multi-wall or single-wall carbon nano tubes subjected to acid oxidation treatment in a solvent, uniformly mixing, centrifuging, and drying a solid part to obtain composite particles.
In the scheme, O-carboxymethyl chitosan is wrapped on a multi-wall or single-wall carbon nano tube by blending in a solvent, and is subjected to solid-liquid separation in a centrifugal mode, and then is dried to form composite particles, wherein the composite particles can be used independently or used in combination with other adsorbents and the like.
Further, the O-carboxymethyl chitosan and the multiwall carbon nano tube which is treated by acid oxidation are placed in a solvent at the mass ratio of 0.3-0.7;
the O-carboxymethyl chitosan and the single-wall carbon nano tube treated by acid oxidation are placed in a solvent at the mass ratio of 0.003-0.007.
Further, placing O-carboxymethyl chitosan in a solvent, performing ultrasonic dispersion to form a chitosan solution, placing the multiwall carbon nanotube subjected to acid oxidation treatment in the chitosan solution, performing low-temperature crushing and dispersion, taking an upper layer solution for centrifugal separation, and drying a solid part to obtain composite particles, wherein the mode that the multiwall or single-wall carbon nanotube is added into the chitosan solution is preferred, the low-temperature crushing treatment promotes uniform dispersion, the coating or coating of chitosan on the multiwall carbon nanotube wall is completed, and the composite particles can be obtained after centrifugal drying.
Further, the low-temperature crushing and dispersing means that the mixed solution of the multi-wall nano tube and the chitosan is crushed and dispersed by ultrasonic waves at the temperature of 0-10 ℃, and the solid part after centrifugal separation is dried in an oven, such as the multi-wall or single-wall carbon nano tube, and is dried in the oven at the temperature of 50-80 ℃.
Further, the preparation of the O-carboxymethyl chitosan comprises the following steps:
1) Swelling chitosan in alcohol solution, and then adding sodium hydroxide to degrade the chitosan;
2) Mixing the degradation solution of chitosan with chloroacetic acid alcohol solution, and reacting at 45-55 ℃;
3) And (3) placing the product prepared in the step (2) into an alcohol solution, adding acid for treatment, and drying the prepared product to obtain the O-carboxymethyl chitosan.
Further, the preparation of the multi-wall or single-wall carbon nanotubes treated with acid oxidation comprises the steps of:
1) Placing the multi-wall carbon nano tube in acid, and carrying out ultrasonic treatment;
2) Refluxing the acid solution of the multi-wall or single-wall carbon nano tube in the step 1) for 6-10h;
3) Washing the product obtained in the step 2), and then drying.
Preferably at 75-85 ℃.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention forms composite particles by wrapping O-carboxymethyl chitosan on multi-wall or single-wall carbon nano tubes subjected to acid oxidation treatment, the combination mode is obviously different from the adsorption mechanism of the prior published data, and the adsorption effect on heavy metal lead is excellent.
Drawings
FIG. 1 is an infrared spectrum of MWCNTs (a), oMWCNTs (b), WSCC/oMWCNTs (c);
FIG. 2 is a Raman spectrum of MWCNTs (a), oMWCNTs (b), WSCC/oMWCNTs (c);
FIG. 3 is a transmission image of MWCNTs (a), oMWCNTs (b), WSCC/oMWCNTs (c);
FIG. 4 is a graph showing the effect of WSCC/oMWCNTs usage on Pb (II) adsorption in a water sample;
FIG. 5 is a graph showing the effect of pH on Pb (II) adsorption in a water sample when WSCC/oMWCNTs is an adsorbent;
FIG. 6 is an effect of adsorption time on Pb (II) adsorption in water samples when WSCC/oMWCNTs is an adsorbent;
FIG. 7 is a graph of a WSCC/oSWCNTs fit to Pb (II) adsorption kinetics;
FIG. 8 is the effect of initial Pb (II) concentration on WSCC/oSWCNTs adsorption rate;
FIG. 9 is a graph of adsorption isotherms fit of WSCC/oSWCNTs to Pb (II);
FIG. 10 is a graph showing the effect of temperature on Pb (II) adsorption in a water sample when WSCC/oSWCNTs is the adsorbent;
FIG. 11 is an adsorption curve for SWCNTs, oSWCNTs and WSCC/oSWCNTs composites at different pH values of 2-6;
FIG. 12 is SEM and TEM images of SWCNTs and oSWCNTs;
FIG. 13 is a Raman spectrum of SWCNTs, oSWCNTs, WSCC/oSWCNTs composite;
FIG. 14 is the effect of the amount of adsorbent WSCC/oSWCNTs on Pb (II) adsorption in a water sample;
FIG. 15 is an XRD spectrum of (a) before (a) after (b) adsorption of Pb (II) by WSCC/oMWCNTs;
wherein, in the attached figures 1,2 and 3, the marks are as follows:
a represents MWCNTs, b represents oMWCNTs, c represents WSCC/oMWCNTs;
The marks in fig. 11, 12 and 13 are as follows:
a represents SWCNTs, b represents oSWCNTs, and c represents WSCC/oSWCNTs.
Detailed Description
The invention will be further described with reference to the drawings and the specific examples.
Materials and reagents: multiwall carbon nanotubes (manufacturer: shenzhen national constant navigation technology, trade name: CVD method for preparing multiwall carbon nanotubes, purity > 95%, inner diameter 3-5nm, outer diameter 8-15nm, length 3-12 μm), concentrated nitric acid (analytically pure), absolute ethyl alcohol (analytically pure), chitosan (Aladin, M n＝1.2x105 Da, deacetylation degree=80%), chloroacetic acid, sodium hydroxide, glacial acetic acid, methanol, 95% ethanol and absolute ethyl alcohol are analytically pure, lead nitrate (37%, analytically pure), acetone (analytically pure), deionized water.
The preparation of O-carboxymethyl chitosan is as follows: 10g of solid chloroacetic acid was weighed, and 50mL of ethanol was added to dissolve the solid chloroacetic acid, to obtain an alcoholic solution of chloroacetic acid. Weighing 5g of chitosan, adding 100mL of ethanol, standing for 2 hours to fully swell the chitosan, continuously adding 20mL of 50% NaOH aqueous solution with mass fraction, standing for 0 hour to fully degrade the chitosan, and obtaining an alcohol solution of the chitosan. And (3) dropwise adding chloroacetic acid alcohol solution under magnetic stirring, heating the reaction system to 50 ℃, reacting at constant temperature for 5 hours, cooling, filtering, and washing a filter cake with absolute ethyl alcohol to obtain a water-soluble carboxymethyl chitosan sodium salt crude product. Adding the crude product into 100mL of 95% ethanol solution, continuously adding 20mL of glacial acetic acid, magnetically stirring at normal temperature for 1h, filtering, washing and purifying until filtrate is neutral, and drying to obtain white solid water-soluble carboxymethyl chitosan (water-so l ub le carboxymethy l ch itosan, WSCC for short), namely O-carboxymethyl chitosan, wherein the water solubility of the chitosan is improved due to the fact that carboxylic acid groups are introduced into the composition.
The multiwall carbon nanotubes treated with acid oxidation were prepared as follows: 1.0g of multi-walled carbon nanotubes (MWCNTs) was added to 100mL of HNO 3 solution and sonicated for 20min. Sonication facilitates the separation and uniform dispersion of MWCNTs in an acidic solution. Subsequently, the mixture was refluxed at 80 ℃ for 8 hours, introducing carboxylic acid and hydroxyl functional groups at the surface of MWCNTs. After the oxidation treatment, distilled water was added to wash to remove unreacted acid. The oxidized MWCNTs were collected by centrifugation and dried in a vacuum oven at 55deg.C to form acid-oxidized multiwall carbon nanotubes (oMWCNTs).
Single-walled carbon nanotubes (SWCNTs) treated with acid oxidation were prepared as follows: to prepare oxidized SWCNTs, 10mg of SWCNTs are suspended in 100ml of nitric acid for 20min, sonicated to facilitate separation and uniform dispersion of the SWCNTs in an acidic solution. The mixture was then refluxed at 60 ℃ for 6 hours to introduce carboxylic acid and hydroxyl functionalities onto the SWCNTs surface. After the oxidation treatment, the clear yellow solution of the top layer was decanted. The isolated SWCNTs were then collected on filter paper and washed with distilled water to remove unreacted acid. The wet cake was dried in a vacuum oven at 100deg.C for 2 hours and the oxidized SWCNTs product was designated oSWCNTs.
1. The preparation of the carbon nano composite adsorbent is as follows
1.1, Multiwall carbon nanotubes
Example 1
Adding 1.0g of WSCC into 100mL of water, performing ultrasonic dispersion for 10min to obtain a WSCC aqueous solution, adding 2g oMWCNTs into the solution, performing ultrasonic crushing and dispersion for 2h at 0 ℃ by using an ultrasonic crusher, taking the upper layer of 80% solution, performing centrifugal separation, cleaning a wet cake by using distilled water, and drying in a low-pressure oven at 60 ℃ to obtain oMWCNTs which is dispersible in water, namely composite particles, named as WSCC/oMWCNTs, for later use.
Example 2
Adding 0.6g of WSCC into 100mL of water, performing ultrasonic dispersion for 10min to obtain a WSCC aqueous solution, adding 2g oMWCNTs to the solution, performing ultrasonic crushing and dispersion for 2h at 5 ℃ by using an ultrasonic crusher, taking the upper layer of 80% solution, performing centrifugal separation, cleaning a wet cake by using distilled water, and drying in a low-pressure oven at 60 ℃ to obtain oMWCNTs dispersible in water for later use.
Example 3
Adding 1.4g of WSCC into 100mL of water, performing ultrasonic dispersion for 10min to obtain a WSCC aqueous solution, adding 2g oMWCNTs to the solution, performing ultrasonic crushing and dispersion for 2h at 5 ℃ by using an ultrasonic crusher, taking the upper layer of 80% solution, performing centrifugal separation, cleaning a wet cake by using distilled water, and drying in a low-pressure oven at 60 ℃ to obtain oMWCNTs dispersible in water for later use.
1.2 Single wall carbon nanotubes
Example 4
1.0G of WSCC was added to 100mL of water, and the mixture was sonicated for 10 minutes to prepare an aqueous WSCC solution, 5mg oSWCNTs was added to the solution, sonicated and dispersed at 10℃for 1 hour with a sonicator, centrifuged at 3000rpm, and 80% of the upper solution was collected, and the dispersed oSWCNTs was filtered with a 0.45 μm polytetrafluoroethylene filter. After filtration and collection, the dispersed carbon nanotubes were thoroughly washed with distilled water to remove excess carbon nanotubes, and then dried at 60 ℃ to obtain dispersible carbon nanotubes. This product was designated WSCC/oSWCNTs composite.
Example 5
1.0G of WSCC was added to 100mL of water, and the mixture was sonicated for 10 minutes to prepare an aqueous WSCC solution, 3mg oSWCNTs was added to the solution, the dispersion was sonicated at 10℃for 1 hour with a sonicator, centrifuged at 3000rpm, and 80% of the upper solution was collected, and the dispersed oSWCNTs was filtered through a 0.45 μm polytetrafluoroethylene filter. After filtration and collection, the dispersed carbon nanotubes were thoroughly washed with distilled water to remove excess carbon nanotubes, and then dried at 60 ℃ to obtain dispersible carbon nanotubes.
Example 6
1.0G of WSCC was added to 100mL of water, and the mixture was sonicated for 10 minutes to prepare an aqueous WSCC solution, 7mg oSWCNTs was added to the solution, sonicated and dispersed at 10℃for 1 hour with a sonicator, centrifuged at 3000rpm, and 80% of the upper solution was collected, and the dispersed oSWCNTs was filtered with a 0.45 μm polytetrafluoroethylene filter. After filtration and collection, the dispersed carbon nanotubes were thoroughly washed with distilled water to remove excess carbon nanotubes, and then dried at 60 ℃ to obtain dispersible carbon nanotubes.
2. Characterization of
Multiwall carbon nanotubes: as shown in FIG. 1, when oMWCNTs and MWCNTs were compared, it was noted that new bands appeared at 1183cm -1、1769cm-1 and 3288cm -1. The first band is due to the stretching of C-O in oMWCNTs, while the last two bands are related to the stretching of c=o and O-H in the COOH group. The appearance of these bands indicated that pMWCNTs was successfully oxidized.
All three spectra have bands of 3023cm -1 and 1641cm -1, corresponding to C-H and c=c stretching, respectively. However, the 1641cm -1 band on oMWCNT spectra broadened, indicating successful purification of MWCNTs, while the 1641cm -1 band on WSCC/oMWCNT spectra was tapered as a result of the p-pi interaction between oMWCNTs and WSCC, indicating successful preparation of WSCC/oMWCNTs nanocomposite. On the other hand, the WSCC/oMWCNTs spectra had C-O and O-H telescopic vibrational bands of 1259cm -1 and 3410cm -1, respectively. The tensile and flexural vibration peaks of N-H are found at 1598cm -1 and 3431cm -1 in WSCC, and the tensile vibration peak of C-H is found at 1347cm -1.
As shown in FIG. 2, the Raman spectrum at an excitation wavelength of 633nm, the MWCNTs have two vibrational peaks between 1000-2000cm -1, a D peak of about 1350cm -1 and a G peak of about 1580cm -1. The D peak is generally attributed to the presence of amorphous or disordered carbon in the MWCNTs sample, and the intensity ratio (I D/IG) accounts for the extent of MWCNTs defects and performance index.
The I D/IG ratio (1.16) of oMWCNTs is higher than the I D/IG ratio (1.07) of MWCNTs, indicating that the amorphous carbon is removed after the acid treatment of the MWCNTs, resulting in sidewall defects. This improves the dispersibility of oMWCNTs in aqueous solutions. Likewise, the I D/IG ratio (1.24) of WSCC/oMWCNTs was also higher than oMWCNTs, which was also the result of a further increase in the extent of oMWCNTs sidewall defects. This can be attributed to the electrostatic interaction between oMWCNTs and WSCC, which further improves the dispersibility of oMWCNTs in aqueous solutions.
As shown in FIG. 3, part a of the drawing is a TEM image of MWCNTs, the whole image is somewhat blurred, and other carbon impurities are distributed among the SWCNTs bundles. In the TEM image with part b being oMWNTs in the figure, the impurity carbon particles are clearer, and the small pipe diameter oMWNTs can be more clearly observed, which shows that the nitric acid acidification treatment removes a large amount of carbon impurities and improves the purity of MWCNTs. More importantly, the introduction of the water-soluble functional group in the process weakens the Van der Waals force among the MWCNTs, improves the dispersibility of the MWCNTs, and improves the surface adsorption efficiency of the MWCNTs. In the TEM image of WSCC/oMCWNT, part c shows that the surface of oMCWNTs is non-uniform and WSCC is hazy wrapped on the surface of oMCWNTs, which morphologically illustrates the successful preparation of WSCC and oMCWNT nanocomposite, consistent with the results of the infrared spectrum. More importantly, the water-soluble WSCC increases the dispersibility of oMWCNTs, increases the specific surface area of the WSCC, and further enhances the adsorption capacity of the material.
Single-wall carbon nanotubes: the effectiveness of the purification process is clearly shown by the nitric acid treatment on the left and the nitric acid treatment on the right, as shown in fig. 12. The entire SWCNTs image (left on the figure) is somewhat blurred, and other carbon impurities are also distributed between SWCNTs bundles. The right oSWCNTs image on the figure is clear and the figure shows that the surface of oSWCNTs is uneven due to uniform scattering of WSCC thereon, and it can be seen that the nitric acid treatment has a substantially uniform effect on single-wall or multi-wall carbon nanotubes. Meanwhile, FIG. 13 shows the Raman spectra of SWCNTs (a), oSWCNTs (b) and WSCC/oSWCNTs composite (c) at an excitation wavelength of 633nm, with oSWCNTs having a ratio of I D/IG (0.084) higher than the ratio of I D/IG (0.060) of SWCNTs, indicating that the acid treated SWCNTs have had amorphous carbon removed, resulting in sidewall defects. This improves the dispersibility of the water-soluble carbon nanotubes in an aqueous solution. Likewise, the WSCC/oSWCNTs composite has a I D/IG ratio (0.092) higher than oSWCNTs, which also results in increased oSWCNTs sidewall defects. This is probably due to the electrostatic interaction between oSWCNTs and WSCC, which increases the dispersibility of the WSCC/oSWCNTs composite in aqueous solutions, thereby enhancing its adsorption capacity to adsorbents. The infrared spectra made at the same time also showed that the carbon nanotubes were successfully oxidized, which is consistent with the conclusion of the raman spectroscopy study, and in addition, the infrared spectra of the WSCC and WSCC/oSWCNTs composites also showed that the N-H characteristic absorption peak of the WSCC sample shifted from 1652cm -1 to 1658cm -1 of the WSCC/oSWCNTs composite. The weakening of the N-C bond is due to the transfer of the lone pair of electrons from WSCC to oSWCNTs, which is a result of the p-pi interaction of oSWCNTs with WSCC, suggesting that the binding of WSCC to oSWCNTs is stable.
3. Adsorption experiment
3.1, Adsorption of Pb (II) in water sample by WSCC/oMWCNTs dosage
Weighing WSCC/oMWCNTs prepared in example 1 into a separate 250mL conical flask, adding 100.0mL of Pb (I) solution with initial concentration of 100 mg.L -1, adding different amounts of WSCC/oMWCNTs under the condition of quantitative initial concentration of 100 mg.L -1, vibrating for 1h at room temperature, centrifugally filtering, obtaining the residual Pb (I) concentration in a water sample by using an atomic absorption spectrophotometer (AA 320N), wherein 99% of Pb (I) is absorbed in 1h when the amount of WSCC/oMWCNTs is 2 mg.mL -1, and the further increase of the amount of the adsorbent does not improve the adsorption efficiency of Pb (I), and is almost unchanged. This is a result of the reduced surface area as the adsorbent begins to agglomerate at higher concentrations in the solution.
3.12 Influence of pH
The influence of pH on the Pb (I) removing adsorption capacity of WSCC/oMWCNTs was studied, 100.0mL of Pb (I) solution with an initial concentration of 100 mg.L -1 was added into a separate 250mL conical flask, the pH was adjusted with acid, and the adsorption experiment was carried out under different pH conditions of 2-6, in which the amount of WSCC/oMWCNTs was 2 mg.mL -1, as shown in FIG. 5, under the low pH condition, the Pb (I) removing rate of WSCC/oMWCNTs was very low, and the Pb (I) removing rate was gradually increased with the increase of pH. This is probably because at lower pH values, most of the free oxygen on the adsorbent is protonated. Therefore, WSCC/oMWCNTs having a protonated positively charged surface repels metal ions through electrostatic repulsion, does not participate in complex formation, resulting in low metal ion removal rates. With the increase of the pH value of the solution, the protonation effect is weakened, and the adsorbent can provide more adsorption sites, so that the metal ion removal rate is gradually increased, and the adsorption rate of WSCC-MWCNTs on Pb (II) can reach 98% at the pH value of 6. Thus, for this adsorption experiment, ph=6 is the optimal pH.
3.13 Influence of adsorption time
A separate 250mL Erlenmeyer flask was charged with 100.0mL of Pb (I) solution having an initial concentration of 100 mg.L -1 and a WSCC/oMWCNTs dose of 2 mg.mL -1, as shown in FIG. 6, and the adsorption rate of WSCC-MWCNTs on Pb (I) was very fast within 40 minutes of adsorption time. After about 60min, adsorption gradually reached an equilibrium stage. The rapid adsorption may be due to the presence of a large number of active binding sites on the surface of WSCC-MWCNTs. Pb (II) occupies most of the empty active site surface during 40min of contact time. After 40min of contact time, the adsorption rate was reduced due to gradual decrease of adsorption binding sites on the adsorbent or slow diffusion of Pb (II) into the pores. Therefore, the optimal contact time for adsorption experiments was 60min.
3.2 Adsorption of Pb (II) in Water by WSCC/oSWCNTs composite Material
3.21 Influence of pH
As shown in FIG. 11, the adsorption experiment shows that the removal rate of Pb (II) by using the WSCC/oSWCNTs (curve c) composite adsorbent is increased from 30% to 98% when the pH value is 2 to 6, and at the same time, the removal rate is increased from 12% to 78% when oSWCNTs (curve b) is used as the adsorbent, and the removal rate of SWCNTs is increased from 6% to 59% when the adsorption experiment is carried out under 298K conditions, wherein the adsorbent dose is 100mg, and the Pb (I I) dose is 10mg, and the adsorption is carried out in 100mL of solution for 60 minutes. In general, from a to b to c, the more defects the functionalized nanotubes have, the higher the adsorption performance, and in addition, the adsorption performance is gradually enhanced with increasing pH, and the adsorption rate of WSCC/oSWCNTs composite material to Pb (ii) is as high as 98% at ph=6, which is considered to be the optimal pH.
Similarly, the pH influence tests were carried out on WSCC (curve a) and oSWCNTs (curve b), and as shown in curve a and curve b in FIG. 11, the adsorption performance was gradually increased with the increase of the pH value.
3.22 Influence of WSCC/oSWCNTs Complex dose
Adsorption experiments are carried out for 60 minutes under the conditions that the temperature is 303K and the solution volume is 100mL, 1-4mg/mL of WSCC/oSWCNTs composite material is added into a water sample with the Pb (I) concentration of 100mg/mL, and after the water sample is stirred for 60 minutes, the residual concentration and the removal rate of Pb (I) in the water sample are measured. As shown in FIG. 14, WSCC/oSWCNTs at a dose of 2mg/mL had an adsorption of 98% to Pb (II) at 60min, and the adsorption of Pb (II) was almost unchanged by further increasing the amount of adsorbent, because: the effective adsorption surface area decreases as the composite material begins to agglomerate with increasing concentration of WSCC/oSWCNTs in solution.
3.23 Influence of temperature
Adsorption experiment under the condition that the volume of a solution is 100mL, adding 2mg/mL of WSCC/oSWCNTs composite material into a water sample with the concentration of Pb (I) of 100mg/mL, stirring the water sample for 60min, and then measuring the residual concentration and the removal rate of Pb (I) in the water sample, wherein the adsorption performance adsorption result of WSCC/oSWCNTs on Pb (I) in the solution is shown in FIG. 10 when the temperatures are 20, 25, 30, 35 and 40 ℃, and the adsorption amount of WSCC/oSWCNTs is increased along with the increase of the reaction temperature, and the maximum adsorption amount is shown as the reaction temperature is 30 ℃. The WSCC/oSWCNTs has better adsorption effect at higher temperature because the viscosity of Pb (II) at higher temperature is reduced, the movement speed of Pb (II) is fast, and the mass transfer resistance is reduced. In addition, the higher the temperature, the easier the deprotonation reaction proceeds, and more active sites are released, thereby improving the adsorption effect of WSCC/oSWCNTs on Pb (II). But an increase in temperature promotes agglomeration of WSCC/oSWCNTs, which reduces the surface area of WSCC/oSWCNTs. The result of the combined action of the two factors is that the adsorption capacity tends to be smooth at a temperature of 30 ℃.
The effect of temperature on the adsorption performance of WSCC/oMWCNTs was also examined according to the above test conditions. Also, the adsorption capacity tended to be smooth at 30℃consistent with WSCC/oSWCNTs.
3.24 Influence of initial concentration
Adsorption experiment under the condition that the temperature is 30 ℃ and the solution volume is 100mL, adding 2mg/mL of the WSCC/oSWCNTs composite material, stirring a water sample for 60min, and then measuring the residual concentration and the removal rate of Pb (I) in the water sample, wherein as shown in figure 8, when the initial concentration is 20 mg.L -1, the adsorption efficiency of the WSCC/oSWCNTs composite material on Pb (I) in the solution is 99.2%. As the concentration of Pb (ii) in the solution increases, the adsorption efficiency of the WSCC/oSWCNTs composite gradually decreases. When the Pb (II) concentration in water is low, pb (II) can be quickly adsorbed to available WSCC/oSWCNTs complex sites due to less competition between Pb (II) ions. Therefore, the removal rate of Pb (II) is higher at a lower concentration, but as the concentration of Pb (II) in the solution increases, the ratio of effective binding sites to Pb (II) gradually decreases. Therefore, pb (ii) tends to saturate at a limited binding site, and is difficult to adsorb.
The effect of initial Pb (II) concentration was also tested on WSCC/oMWCNT according to the test procedure described above, and the results were consistent with WSCC/oSWCNTs.
3.3 Adsorption Rate and adsorption mechanism
The rate of the quasi-first order dynamics determines the step physical diffusion process. The quasi-second order kinetic rate limiting step is a chemical process. The linear quasi-first order dynamics is shown as a formula (3), and the linear quasi-second order dynamics is shown as a formula (4).
ln(qe-qt)＝lnqe-k1t........(3)
The adsorption kinetics of WSCC/oSWCNTs on Pb (II) was studied using quasi-primary and quasi-secondary kinetic models. Where q e and q t are the amounts of heavy metal ions adsorbed by WSCC/oSWCNTs at equilibrium and time t (min) (mg g -1),k1 is the first order kinetic constant (min -1),k2 is the second order kinetic constant (min -1)).
Two kinetic models were discussed according to equation (3) and equation (4) in combination with the data from the experimental conditions above, the most appropriate model was selected based on the value of the highest fitting coefficient (R 2). The adsorption kinetics of Pb (II) on WSCC/oSWCNTs composites were studied. FIG. 7a is a graph of a quasi-first order kinetic adsorption fit of a WSCC/oSWCNTs composite to Pb (II), and FIG. 7b is a graph of a quasi-second order kinetic adsorption fit of a WSCC/oSWCNTs composite to Pb (II). From the fitting results, it can be seen that the first order kinetics fit R 2 is significantly smaller, the adsorption curve fit is not ideal, while the second order kinetics fit R 2 reaches 0.99589, the adsorption process follows the second order kinetics model, indicating that the adsorption process involves chemisorption. The dynamic adsorption research is also carried out on WSCC/oMWCNTs, and the WSCC/oMWCNTs is consistent with WSCC/oSWCNTs and accords with a secondary dynamic model.
3.4 Adsorption isotherms
Adsorption isotherms are used to explain the adsorption pattern or distribution of the adsorbate on the adsorbent when the adsorption process reaches equilibrium. Langmu i r and Freund's back are two commonly used adsorption isotherm models. Langmu i r adsorption isotherms illustrate the single-layer adsorption at the same position on the surface of the adsorbent, and the adsorption energy is uniform, as shown in formula (5). The Freund's ICh adsorption isotherm considers reversible multi-layer adsorption at heterogeneous adsorption sites of different adsorption energies. The Freund's ich adsorption isotherm can be expressed by equation (6).
B and q 0 in the formula (5) represent the Langmu i r adsorption constant (l·mg -1) and the maximum adsorption capacity (mg·g -1), respectively. K F in the formula (6) is Freund's ich adsorption isotherm constant (mg.g -1)/(mg·L-1)1/n, which is related to adsorption energy, n is adsorption strength, and detailed information of the degree of non-uniformity.1/n.ltoreq.1 indicates the feasibility of the adsorption process.
Under the optimal experimental conditions, the average intermittent adsorption balance data of the WSCC/oSWCNTs composite material on Pb (II) in water is utilized to examine the relationship between the equilibrium concentration and the adsorption quantity when the adsorption reaches equilibrium at a certain temperature. Two adsorption isotherms were fitted using equations (5) and (6), respectively, with the fitting results shown in fig. 9a (Langmu i r fitting curve) and fig. 9b (Freund l ich fitting curve).
From the fitting results, it can be seen that the adsorption of Pb (II) by WSCC/oSWCNTs is in accordance with both Langmu I r isothermal adsorption model and Freund's ich isothermal adsorption model. The adsorption process is described to include both monolayer adsorption and multi-molecular layer adsorption. But multi-molecular layer adsorption predominates. Meanwhile, the adsorption process of WSCC/oSWCNTs on Pb (II) is very complex, and various adsorption mechanisms such as an ion exchange process (COOH-Pb (II)), an electrostatic attraction process (coulomb attraction) and complexation (N-Pb (II) coordination bond) can be included. The maximum adsorption q 0 obtained by Langmu i r model fitting is 113.63 mg.cndot.g-1, and the model equation is shown in the equation of FIG. 9 a. N=0.519, obtained by fitting the Freund l ich model, and the model equation is shown in the equation in fig. 9b, which shows that adsorption of Pb (ii) by WSCC/oSWCNTs is very easy, i.e., the WSCC/oSWCNTs adsorbent used in the experiment has a strong adsorption capacity for Pb (ii).
And simultaneously, carrying out isothermal adsorption model test on WSCC/oMWCNTs, and fitting Langmu i r equation: y=0.10343x+0.0009319, r 2 = 0.99768, the amount of the adsorbent WSCC-oMWCNTs to be added can be determined by using this fitting equation according to the actual water quality and the requirement of Pb (ii) balance. The fitted Freund l ich isotherm equation is: y=0.94321x+2.29432, r 2 = 0.98824, the amount of WSCC/oMWCNTs added to the adsorbent can be determined by using this fitting equation according to the actual water quality and the requirement for Pb (ii) balance.
To further examine the adsorption mechanism of WSCC/oMWCNTs to Pb (II), XRD tests were performed on the adsorbent samples before and after the experiment. FIG. 15 is an XRD spectrum of the WSCC/oMWCNTs nanocomposite before (a) and after (b) Pb (II) adsorption. Wherein 2θ=10.4 and 2θ=19.8 in the spectrum curve a are two characteristic peaks of WSCC, whereas in curve b these two characteristic peaks are significantly reduced, as a result of the presence of forces between Pb (ii) and WSCC/oMWCNTs, forming Pb (ii) -N complexes.
3.5, Control test
3.51 Multiwall carbon nanotubes
Control group 1: 200mg of multi-walled carbon nanotube (oMWCNTs) was weighed into a separate 250mL conical flask, and 100.0mL of Pb (II) solution having an initial concentration of 100 mg.L -1 was added thereto, and the reaction was carried out at room temperature with shaking for 1 hour. After completion of the reaction, the solution was centrifugally filtered, and the concentration of Pb (II) ions was measured to determine the adsorption rate and the maximum adsorption amount.
Control group 2: the same mass of water-soluble carboxymethyl chitosan (WSCC) was weighed into a separate 250mL conical flask, and 100.0mL of Pb (II) solution with an initial concentration of 100 mg.L -1 was added, and the reaction was carried out at room temperature with shaking for 1h. After completion of the reaction, the solution was centrifugally filtered, and the concentration of Pb (II) ions was measured to determine the adsorption rate and the maximum adsorption amount.
Group of examples: the same mass of WSCC/oMWCNTs prepared in example 1 was weighed into a separate 250mL Erlenmeyer flask, and 100.0mL of Pb (II) solution having an initial concentration of 100 mg.L -1 was added thereto, and the reaction was allowed to proceed with shaking at room temperature for 1 hour. After completion of the reaction, the solution was centrifugally filtered, and the concentration of Pb (II) ions was measured to determine the adsorption rate and the maximum adsorption amount.
The results are shown in Table 1:
TABLE 1
As can be seen from the data in Table 1, the adsorption rate and the maximum adsorption amount of Pb (II) by WSCC/oMWCNTs after dispersion are significantly improved as compared with WSCC or oMWCNTs. This illustrates the introduction of WSCC in oMWCNTs, both of which have the ability to synergistically adsorb and remove Pb (II) from water, which greatly increases the adsorption rate of Pb (II).
The above experiments were carried out on the adsorbents in example 2 and example 3, and the results were the same as in example 1.
3.52 Single wall carbon nanotubes
According to the procedure and conditions of the control test of the multi-wall carbon nanotubes, the control test of the single-wall carbon nanotubes was performed as shown in Table 2.
TABLE 2
It can be seen that the adsorption rate and the maximum adsorption amount of Pb (II) by the dispersed WSCC/oSWCNTs are both significantly improved compared to those of WSCC or oSWCNTs. This illustrates the introduction of WSCC in oSWCNTs, both of which have the ability to synergistically adsorb and remove Pb (II) from water, which greatly increases the adsorption rate of Pb (II).
The above experiments were carried out on the adsorbents in example 5 and example 6, and the results were identical to those in example 4.
3.6 Summary
Isotherm studies show that when WSCC/oMWCNTs and WSCC/oSWCNTs adsorb Pb (II), the model accords with a Langmu I r isothermal adsorption model and a Freund's ich isothermal adsorption model. The adsorption process is described to include both monolayer adsorption and multi-molecular layer adsorption. The inner adsorption of Pb (II) ions on WSCC/oMWCNTs, WSCC/oSWCNTs can be attributed to the formation of metal-N complexes between the nanocomposite materials, which is believed to be the mechanism of metal-ion adsorption on WSCC/oMWCNTs, WSCC/oSWCNTs. The negative charges on the acidified oMWCNTs side walls, such as-COOH and-OH, provide electron pairs to the metal ions, thereby facilitating cation exchange, which groups render the carbon nanotubes hydrophilic, and the amino groups of WSCC act to enhance adsorption capacity throughout the adsorption process, which at high pH contribute to efficient adsorption of Pb (ii) for positive and negative charges.
In addition, it can be also obtained that the carbon nano composite adsorbent, when applied to a contaminated liquid of heavy metal lead, has preferable conditions: when the initial concentration of Pb (II) is 20mg.L -1, the pH is 6, the adsorption reaction time is 60min, the temperature is 30 ℃, and the optimal concentration of WSCC/oMWCNTs and WSCC/oSWCNTs is 2 mg.mL -1.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.
Claims (8)
1. The application of the carbon nano tube composite adsorbent in adsorbing Pb ions is characterized in that: comprises coating O-carboxymethyl chitosan on the surface of a multi-wall or single-wall carbon nano tube treated by acid oxidation to form composite particles, wherein the pH is 6, the adsorption reaction time is 60min, the temperature is 30 ℃, and the concentration of WSCC/oMWCNTs or WSCC/oSWCNTs is 2 mg.mL −1;
mixing the O-carboxymethyl chitosan and the multiwall carbon nanotube subjected to acid oxidation treatment in a solvent at a mass ratio of 0.3-0.7, and drying solid components separated by centrifugation to obtain composite particles;
The O-carboxymethyl chitosan and the single-wall carbon nano tube treated by acid oxidation are mixed in a solvent under the mass ratio of 0.003-0.007, and the solid components separated by centrifugation are dried to obtain the composite particles.
2. The use according to claim 1, wherein: the O-carboxymethyl chitosan is prepared by reacting chitosan with chloroacetic acid in an alkaline medium.
3. The use according to claim 1, wherein: the multi-wall or single-wall carbon nanotubes are oxidized with nitric acid.
4. The use according to claim 1, wherein: placing O-carboxymethyl chitosan and multi-wall or single-wall carbon nano tube treated by acid oxidation in a solvent, uniformly mixing, centrifuging and drying a solid part to obtain the composite particles.
5. The use according to claim 4, wherein: placing O-carboxymethyl chitosan in a solvent, performing ultrasonic dispersion to form a chitosan solution, placing multi-wall or single-wall carbon nanotubes subjected to acid oxidation treatment in the chitosan solution, performing low-temperature crushing dispersion, taking an upper layer solution for centrifugal separation, and drying a solid part to obtain composite particles.
6. The use according to claim 5, wherein: the low-temperature crushing and dispersing means that the multi-wall or single-wall carbon nano tube and chitosan mixed solution are crushed and dispersed by ultrasonic waves at the temperature of 0-10 ℃, and the solid part after centrifugal separation is placed in an oven for drying.
7. The use according to claim 4, wherein: the preparation of the O-carboxymethyl chitosan comprises the following steps:
1) Swelling chitosan in alcohol solution, and then adding sodium hydroxide to degrade the chitosan;
2) Mixing the degradation solution of chitosan with chloroacetic acid alcohol solution, and reacting at 45-55 ℃;
3) And (3) placing the product prepared in the step (2) into an alcohol solution, adding acid for treatment, and drying the prepared product to obtain the O-carboxymethyl chitosan.
8. The use according to claim 4, wherein: the preparation of the multi-wall or single-wall carbon nano tube treated by acid oxidation comprises the following steps:
1) Placing the multi-wall carbon nano tube in acid, and carrying out ultrasonic treatment;
2) Refluxing the acid solution of the multi-wall or single-wall carbon nano tube in the step 1) for 6-10h;
3) Washing the product obtained in the step 2), and then drying.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111498976.2A CN114177892B (en) | 2021-12-09 | 2021-12-09 | Carbon nano tube composite adsorbent and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111498976.2A CN114177892B (en) | 2021-12-09 | 2021-12-09 | Carbon nano tube composite adsorbent and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114177892A CN114177892A (en) | 2022-03-15 |
| CN114177892B true CN114177892B (en) | 2024-06-14 |
Family
ID=80542930
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111498976.2A Active CN114177892B (en) | 2021-12-09 | 2021-12-09 | Carbon nano tube composite adsorbent and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114177892B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115582107B (en) * | 2022-10-12 | 2024-01-30 | 福州大学 | Preparation method and application of 3D printing porous material containing carbon nano tubes |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104289200A (en) * | 2014-10-25 | 2015-01-21 | 济南大学 | Preparation method and application of magnetic HACC/oxidized multi-walled carbon nanotube adsorbent |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100702873B1 (en) * | 2005-07-19 | 2007-04-03 | 전북대학교산학협력단 | Carbon nanotube-chitosan composites and method of manufacturing the same |
| CN101664669A (en) * | 2009-09-29 | 2010-03-10 | 中国科学院生态环境研究中心 | Preparation method and application of carboxylated single-walled carbon nanotube-alginic acid solid phase extracting disk |
| KR101303899B1 (en) * | 2011-05-04 | 2013-09-05 | (주)마크스톤 | Method for preparing of polymer-carbon nanotube composite particles |
| US20150041730A1 (en) * | 2012-04-11 | 2015-02-12 | Veijo Kangas | Carbon nanotube - polysaccharide composite |
| CN108017725B (en) * | 2018-01-18 | 2020-05-12 | 西北师范大学 | Preparation and application of multiwalled carbon nanotube-N-carboxymethyl chitosan chiral material |
| CN111672480A (en) * | 2020-06-18 | 2020-09-18 | 威海海洋职业学院 | Crosslinked chitosan-multi-carbon nanotube composite material and application thereof |
-
2021
- 2021-12-09 CN CN202111498976.2A patent/CN114177892B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104289200A (en) * | 2014-10-25 | 2015-01-21 | 济南大学 | Preparation method and application of magnetic HACC/oxidized multi-walled carbon nanotube adsorbent |
Non-Patent Citations (2)
| Title |
|---|
| 水中可分散单壁碳纳米管的制备及光谱分析;高金玲等;《电镀与精饰》;第43卷(第7期);第1.3、2.3节 * |
| 水中可分散单壁碳纳米管的制备及光谱分析;高金玲等;电镀与精饰;20210731;第43卷(第7期);第 1.3、2.3 节 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114177892A (en) | 2022-03-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Ballav et al. | L-cysteine doped polypyrrole (PPy@ L-Cyst): a super adsorbent for the rapid removal of Hg+ 2 and efficient catalytic activity of the spent adsorbent for reuse | |
| Ahmad et al. | Adsorption of methyl orange by synthesized and functionalized-CNTs with 3-aminopropyltriethoxysilane loaded TiO2 nanocomposites | |
| Ghorbani et al. | Adsorptive removal of lead (II) ion from water and wastewater media using carbon-based nanomaterials as unique sorbents: A review | |
| Xu et al. | Adsorption of Cu (II), Pb (II) and Cr (VI) from aqueous solutions using black wattle tannin-immobilized nanocellulose | |
| Torrejos et al. | Synthesis and characterization of multi-walled carbon nanotubes-supported dibenzo-14-crown-4 ether with proton ionizable carboxyl sidearm as Li+ adsorbents | |
| Fan et al. | Fabrication of magnetic chitosan nanoparticles grafted with β-cyclodextrin as effective adsorbents toward hydroquinol | |
| Luo et al. | Non-toxic chitosan-based hydrogel with strong adsorption and sensitive detection abilities for tetracycline | |
| Wan Ngah et al. | Malachite green adsorption onto chitosan coated bentonite beads: isotherms, kinetics and mechanism | |
| Shawky et al. | Chitosan/carbon nanotube composite beads: Preparation, characterization, and cost evaluation for mercury removal from wastewater of some industrial cities in Egypt | |
| Zolfaghari | β-Cyclodextrin incorporated nanoporous carbon: host–guest inclusion for removal of p-Nitrophenol and pesticides from aqueous solutions | |
| Qi et al. | Synthesis of quercetin loaded nanoparticles based on alginate for Pb (II) adsorption in aqueous solution | |
| Shirkhanloo et al. | Ultrasound assisted-dispersive-ionic liquid-micro-solid phase extraction based on carboxyl-functionalized nanoporous graphene for speciation and determination of trace inorganic and organic mercury species in water and caprine blood samples | |
| Pan et al. | Facile assembly of hollow polydopamine capsules onto macroporous poly (glycidyl methacrylate) foams for simultaneous removal of λ-cyhalothrin and copper ions | |
| Wang et al. | Adsorption of Cu (II) on oxidized multi-walled carbon nanotubes in the presence of hydroxylated and carboxylated fullerenes | |
| Pena-Pereira et al. | Graphene-based nanocomposites in analytical extraction processes | |
| US9687813B2 (en) | Activated carbon/aluminum oxide/polyethylenimine composites and methods thereof | |
| US10487040B2 (en) | Dye removal from aqueous compositions | |
| Tarley et al. | Study on the performance of micro-flow injection preconcentration method on-line coupled to thermospray flame furnace AAS using MWCNTs wrapped with polyvinylpyridine nanocomposites as adsorbent | |
| Dehaghi | Removal of lead ions from aqueous solution using multi-walled carbon nanotubes: The effect of functionalization | |
| Movaghgharnezhad et al. | Synthesis of cellulose nanofibers functionalized by dithiooxamide for preconcentration and determination of trace amounts of Cd (II) ions in water samples | |
| CN114177892B (en) | Carbon nano tube composite adsorbent and preparation method thereof | |
| Awad et al. | Polyacrylonitrile modified partially reduced graphene oxide composites for the extraction of Hg (II) ions from polluted water | |
| Sitko et al. | Graphene oxide decorated with fullerenol nanoparticles for highly efficient removal of Pb (II) ions and ultrasensitive detection by total-reflection X-ray fluorescence spectrometry | |
| El Hefnawy et al. | Effective removal of Pb (II), Cd (II) and Zn (II) from aqueous solution by a novel hyper cross-linked nanometer-sized chelating resin | |
| Huang et al. | Superb adsorption capacity and mechanism of poly (1-amino-5-chloroanthraquinone) nanofibrils for lead and trivalent chromium ions |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |