CN117923490A - Preparation method and application of multistage activated waste fruit and vegetable peel biological porous carbon - Google Patents
Preparation method and application of multistage activated waste fruit and vegetable peel biological porous carbon Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 93
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 57
- 239000002699 waste material Substances 0.000 title claims abstract description 42
- 235000012055 fruits and vegetables Nutrition 0.000 title claims abstract description 30
- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- 238000001179 sorption measurement Methods 0.000 claims abstract description 56
- 230000004913 activation Effects 0.000 claims abstract description 50
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims abstract description 42
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims abstract description 38
- 238000002156 mixing Methods 0.000 claims abstract description 35
- 239000011148 porous material Substances 0.000 claims abstract description 22
- 238000000197 pyrolysis Methods 0.000 claims abstract description 22
- 239000012855 volatile organic compound Substances 0.000 claims abstract description 19
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 111
- 238000001994 activation Methods 0.000 claims description 50
- 238000010438 heat treatment Methods 0.000 claims description 42
- 235000012828 Citrullus lanatus var citroides Nutrition 0.000 claims description 41
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 39
- 238000005406 washing Methods 0.000 claims description 38
- 239000012298 atmosphere Substances 0.000 claims description 31
- 239000008367 deionised water Substances 0.000 claims description 27
- 229910021641 deionized water Inorganic materials 0.000 claims description 27
- 239000000243 solution Substances 0.000 claims description 26
- 238000005245 sintering Methods 0.000 claims description 25
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 21
- XFZRQAZGUOTJCS-UHFFFAOYSA-N phosphoric acid;1,3,5-triazine-2,4,6-triamine Chemical compound OP(O)(O)=O.NC1=NC(N)=NC(N)=N1 XFZRQAZGUOTJCS-UHFFFAOYSA-N 0.000 claims description 21
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 20
- 238000001035 drying Methods 0.000 claims description 20
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 20
- 238000002791 soaking Methods 0.000 claims description 17
- 238000009210 therapy by ultrasound Methods 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 15
- 239000005539 carbonized material Substances 0.000 claims description 11
- 230000007935 neutral effect Effects 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 6
- 240000008790 Musa x paradisiaca Species 0.000 claims description 5
- 235000018290 Musa x paradisiaca Nutrition 0.000 claims description 5
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 claims description 5
- 229910000397 disodium phosphate Inorganic materials 0.000 claims description 5
- 235000019800 disodium phosphate Nutrition 0.000 claims description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 4
- 239000012266 salt solution Substances 0.000 claims description 4
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 4
- 229910000403 monosodium phosphate Inorganic materials 0.000 claims description 3
- 235000019799 monosodium phosphate Nutrition 0.000 claims description 3
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 3
- 239000004254 Ammonium phosphate Substances 0.000 claims description 2
- 244000241257 Cucumis melo Species 0.000 claims description 2
- 240000000716 Durio zibethinus Species 0.000 claims description 2
- 235000006025 Durio zibethinus Nutrition 0.000 claims description 2
- 241000132456 Haplocarpha Species 0.000 claims description 2
- 244000157072 Hylocereus undatus Species 0.000 claims description 2
- 235000018481 Hylocereus undatus Nutrition 0.000 claims description 2
- 244000061456 Solanum tuberosum Species 0.000 claims description 2
- 235000002595 Solanum tuberosum Nutrition 0.000 claims description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 2
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 2
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 2
- 229910000148 ammonium phosphate Inorganic materials 0.000 claims description 2
- 235000019289 ammonium phosphates Nutrition 0.000 claims description 2
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 2
- 239000011790 ferrous sulphate Substances 0.000 claims description 2
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 2
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 2
- 239000011592 zinc chloride Substances 0.000 claims description 2
- 235000005074 zinc chloride Nutrition 0.000 claims description 2
- 244000241235 Citrullus lanatus Species 0.000 claims 1
- 235000009847 Cucumis melo var cantalupensis Nutrition 0.000 claims 1
- 150000002505 iron Chemical class 0.000 claims 1
- 238000003763 carbonization Methods 0.000 abstract description 18
- 150000003839 salts Chemical class 0.000 abstract description 8
- 229910052751 metal Inorganic materials 0.000 abstract description 7
- 230000008901 benefit Effects 0.000 abstract description 6
- 239000002184 metal Substances 0.000 abstract description 5
- 230000009286 beneficial effect Effects 0.000 abstract description 4
- 238000005470 impregnation Methods 0.000 abstract description 4
- 230000003321 amplification Effects 0.000 abstract 1
- 238000003199 nucleic acid amplification method Methods 0.000 abstract 1
- 238000011084 recovery Methods 0.000 abstract 1
- 241000219109 Citrullus Species 0.000 description 40
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 29
- 238000001291 vacuum drying Methods 0.000 description 24
- 238000011282 treatment Methods 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 20
- 238000000227 grinding Methods 0.000 description 16
- 229910052742 iron Inorganic materials 0.000 description 12
- 238000007598 dipping method Methods 0.000 description 11
- 238000001816 cooling Methods 0.000 description 9
- 239000012535 impurity Substances 0.000 description 9
- 239000002028 Biomass Substances 0.000 description 8
- 238000004140 cleaning Methods 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 229910052698 phosphorus Inorganic materials 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 5
- 239000003610 charcoal Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000011574 phosphorus Substances 0.000 description 5
- 241001070941 Castanea Species 0.000 description 4
- 235000014036 Castanea Nutrition 0.000 description 4
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 4
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000002156 adsorbate Substances 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 238000003795 desorption Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- -1 small molecule organic compounds Chemical class 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229920002488 Hemicellulose Polymers 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 238000010000 carbonizing Methods 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 239000001913 cellulose Substances 0.000 description 2
- 229920002678 cellulose Polymers 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 229920005610 lignin Polymers 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
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- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000002336 sorption--desorption measurement Methods 0.000 description 2
- 235000000346 sugar Nutrition 0.000 description 2
- 150000008163 sugars Chemical class 0.000 description 2
- 235000015510 Cucumis melo subsp melo Nutrition 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 241000219000 Populus Species 0.000 description 1
- 244000275012 Sesbania cannabina Species 0.000 description 1
- FJJCIZWZNKZHII-UHFFFAOYSA-N [4,6-bis(cyanoamino)-1,3,5-triazin-2-yl]cyanamide Chemical compound N#CNC1=NC(NC#N)=NC(NC#N)=N1 FJJCIZWZNKZHII-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
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- Carbon And Carbon Compounds (AREA)
Abstract
The invention belongs to the technical field of preparation of biological porous carbon, and discloses a preparation method and application of biological porous carbon for multistage activated waste fruit and vegetable peels. The PBC with ultrahigh specific surface area (3149 m 2/g) and large pore volume (1.76 cm 3/g) is prepared through the steps of ultrasonic impregnation, initial carbonization and activation, ultrasonic impregnation and mixing, co-pyrolysis and activation of the etchant and the phosphide and the like of the waste fruit and vegetable skin through metal salts. Is 102.7 percent of the maximum specific surface area of the prior patent. In addition, the adsorption performance of PBC to VOCs (represented by acetone and n-hexane vapor) is remarkably improved to 1046mg/g and 760mg/g respectively, the amplification is 138% and 132% respectively, and the recovery performance is excellent. The invention realizes the aim of changing waste into valuable in the true sense, is beneficial to improving the energy utilization rate, and has great economic value and social benefit.
Description
Technical Field
The invention relates to a preparation method and application of high-performance multistage activated waste fruit and vegetable peel biological porous carbon, and belongs to the technical field of biological porous carbon preparation.
Background
Along with the continuous promotion of industrialization and urban industry in China, the demand for energy is increasing, fossil energy such as coal and petroleum is used as a main energy supply mode in China, a large amount of volatile organic compounds (Volatile Organic Compounds and VOCs) are generated in the process of promoting economic development in China, and the organic compounds are released into the atmosphere, so that the air quality index is low, and the life quality of people is influenced. Among the numerous VOCs treatment technologies, the adsorption technology has few use limiting conditions, can be suitable for VOCs treatment under multiple conditions, has high adsorption quantity and high adsorption efficiency, can be reused through simple technological measures, and is recognized as an efficient and economic VOCs treatment strategy. The adsorption material is the core of the adsorption technology. The active carbon has the advantages of wide raw materials, large adsorption capacity, low cost, high efficiency and great potential. The biological porous carbon has the advantages of wide and environment-friendly raw material source, developed specific surface area, less pyrolysis products and the like.
At present, the biological porous carbon is mainly prepared by carbonizing single biomass at high temperature, activating KOH, hydrothermally carbonizing and the like, and is applied to the fields of CO 2 adsorption, wastewater treatment, soil remediation and the like. For example, patent CN114130361A uses poplar sawdust as a carbon source, microalgae as a nitrogen source, sesbania powder as a binder, and porous carbon particle materials with the specific surface area up to 1553m 2/g are obtained through high-temperature carbonization, KOH activation and extrusion granulation, and are used for CO 2 adsorption. Patent CN116618018A discloses a phosphorus modified chestnut shell charcoal, a preparation method and application thereof, wherein the chestnut shell charcoal is obtained by carrying out high-temperature pyrolysis treatment under the condition of limiting oxygen, and then is uniformly mixed with sodium dihydrogen phosphate powder and then subjected to hydrothermal reaction, so that the phosphorus modified chestnut shell charcoal is obtained, the specific surface area is 179m 2/g, the micropore volume is 0.103cm 3/g, the average pore diameter is 8.61nm, and the efficient removal of cadmium in water can be realized. The patent CN106010601B is used for preparing the biochar by crushing banana peel, mixing the crushed banana peel with an aqueous solution of an activating agent, drying, mixing the crushed banana peel with an acid solution, and carrying out hydrothermal carbonization reaction, wherein the specific surface area is 550-1200 m 2/g, and the maximum specific surface area is 1189m 2/g, so that the biochar can effectively adsorb Zn, cd, pb or Cu heavy metals. The phosphorus modified chestnut shell hopper biochar is obtained by the patent CN116618018A, the specific surface area is 179m 2/g, and the micropore volume is 0.103cm 3/g.
The biomass source is single, the raw materials are not easy to obtain, and the preparation cost is high; the specific surface area of the prepared porous carbon is not obviously improved compared with that of the active carbon, the pore size distribution is narrow, and the application area is single. Therefore, the biomass porous carbon material with excellent performance is developed by taking low-cost biomass as a raw material and is applied to the adsorption of VOCs, so that the aim of improving atmospheric treatment can be fulfilled, the aims of carbon fixation and emission reduction can be fulfilled, and the application of the biomass porous carbon material to assisting 'double carbon' is hopeful. At present, active carbon prepared by taking biomass as a raw material mainly comprises micropores, and although the micropores are favorable for adsorption of small molecules, the active carbon lacks mesopores, so that the mass transfer rate and the adsorption capacity on macromolecular VOCs are influenced.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the limitation of the prior art and providing a preparation method of multi-stage activated waste fruit and vegetable peel biological porous carbon with ultrahigh specific surface area and application of the multi-stage activated waste fruit and vegetable peel biological porous carbon capable of super-adsorbing VOCs. The biological porous carbon with ultra-micro-mesoporous and ultra-high specific surface area is obtained by multistage activation such as Pi Tanhua activation, ultrasonic impregnation and mixing, co-pyrolysis activation of etchant and phosphide and the like of the waste fruits and vegetables. The finally prepared biological porous carbon has ultrahigh specific surface area reaching 2000-4000m 2/g, can perform super-strong adsorption on VOCs, and the adsorption quantity reaches 500-2000mg/g.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a preparation method of multi-stage activated waste fruit and vegetable peel biological porous carbon comprises the following steps:
(1) Washing, drying and crushing the waste fruit and vegetable peels after pulp removal, performing ultrasonic dipping in 0.1-0.5M ferric salt solution for 4-10 h, then placing in a vacuum atmosphere sintering furnace, heating to 400-500 ℃ at 5-10 ℃/min in an atmosphere of N 2, maintaining for 1-3h, and taking out when the temperature of a sample is reduced to room temperature to obtain carbonized activated fruit and vegetable peel carbonized material PC;
(2) The method comprises the steps of mixing the carbonized fruit and vegetable skin material PC with an etchant according to a mass ratio of 1: fully mixing and drying the mixture according to the proportion of (1-5) to obtain PC-OH; fully mixing and drying PC-OH and phosphide to obtain PC-OH-P; the PC and phosphide are weighed according to the mass ratio of 1 (0.1-0.4).
(3) And (3) placing the PC-OH-P in a vacuum atmosphere sintering furnace for co-pyrolysis activation, and taking out when the temperature of the sample is reduced to room temperature, so as to obtain the activated carbon PAC for the fruit and vegetable peels.
(4) Washing PAC with 1-3mol/L hydrochloric acid solution, fully dissolving and removing residual etchant and other impurities, washing with deionized water until the pH value of the washing water becomes neutral, and then carrying out vacuum drying treatment at 100-120 ℃ until the constant weight is maintained, thereby preparing the multi-stage activated waste fruit and vegetable peel biological porous carbon PBC with ultrahigh specific surface area.
Further, the fruits and vegetables comprise at least one fruit and vegetable which can generate waste skin, namely watermelon, banana, dragon fruit, durian, hami melon and potato. Fruit and vegetable peels are used as raw materials, which are widely available and frequently ignored waste biomass, with specific types of cellulose, hemicellulose, lignin, natural sugars and the like. In an inert atmosphere at about 400 ℃, hemicellulose is decomposed first to produce raw carbon, water vapor and some small molecular organic compounds including acidic substances, aldehydes, ketones and the like. And then the cellulose is decomposed, and the generated product is mainly charcoal. Subsequent decomposition of lignin and natural sugars occurs, with the main products being phenolic compounds, small molecule organic compounds, and char. Different biomass feedstocks produce different carbon structures and functional groups during carbonization or activation.
The ferric salt comprises at least one of ferrous sulfate and ferric nitrate. Ferric salt is physically or chemically adsorbed on the surface of the PC structure at high temperature to form stable metal-carboxylate bond or other bonding to produce modifying effect.
According to the invention, ferric salt is added, the ferric salt and a carbon source precursor are processed together, so that metal elements are uniformly distributed in the whole material, including the surface and the inside, ferric salt solutions which are fully adhered on the surface and the inside of PC can generate iron (such as Fe 0、Fe2O3、Fe3O4) with different forms in an inert atmosphere at about 400 ℃, but mainly generate lower-valence Fe and Fe 0. During initial carbonization, the iron elements are adsorbed on the surface or pores of a PC structure in a physical way, and then react with rich hydroxyl and carboxyl groups of the fruit and vegetable peels at high temperature to form stable metal-carboxylate bonds; on the other hand, the iron element can be chemically bonded with a decomposition product of PC-phenolic compound, and stably anchored on the surface and in pores of PC, so that the performance of the material is improved.
In the subsequent mixing of PC with KOH and phosphide, lower valence Fe and Fe 0 are oxidized to form Fe 2O3, fe 3O4Fe2O3 and Fe 3 O, which on the one hand can endow PC with catalytic performance, improve oxidation-reduction reaction in the secondary activation process and promote subsequent thorough mixing and reaction of PC with KOH and phosphide; on the other hand, new adsorption sites can be formed on the surface of the PBC, so that the adsorption capacity of the PBC on the n-hexane and the acetone is promoted.
Further, the etchant comprises at least one of potassium hydroxide, sodium hydroxide, phosphoric acid, potassium carbonate and zinc chloride.
Further, the method of fully mixing and drying is ultrasonic dipping and mixing, and comprises the following specific steps:
Firstly, dissolving a certain amount of etchant or phosphide with deionized water according to the proportion of 1: (5-10), slowly adding PC into KOH solution until the PC is fully immersed, and moving the PC into an ultrasonic container for ultrasonic treatment for 10-30min to fully mix the PC and the KOH solution;
After being uniformly mixed, the mixture is dried in vacuum at 100-120 ℃ until the constant weight is maintained, and the mixture is taken out and uniformly ground when the temperature of the sample is reduced to room temperature.
Further, the phosphide needs to have higher nitrogen content and phosphorus content, the nitrogen content is 30% -50%, the phosphorus content is 10% -30%, and the phosphide which can generate gas at high temperature comprises one of melamine phosphate, ammonium phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate and sodium hydrogen phosphate. Melamine phosphate is further preferred.
Further, the pyrolysis activation conditions of the vacuum atmosphere sintering furnace are as follows: heating to 700-1000deg.C at 5-10deg.C/min in N 2 atmosphere and maintaining for 1-3 hr.
Further, the biological porous carbon is applied to the adsorption of VOCs; further applied to the adsorption of acetone or/and n-hexane.
The beneficial effects are that:
(1) The biological porous carbon with ultrahigh specific surface area and pore volume is prepared by using widely available and environment-friendly waste fruit and vegetable peels as raw materials and using N, P-enriched phosphide as a modifier through multistage activation methods such as ultrasonic impregnation of metal salt, initial carbonization and activation, co-pyrolysis and activation of etchant and phosphide and the like. The preparation method has simple process, the raw materials are green and environment-friendly, and the preparation process can fully utilize the fruit and vegetable skin waste, avoid secondary pollution to the environment and waste of resources, and realize the aim of changing waste into valuable in the real sense.
(2) The average specific surface area of the active carbon in the market is about 1500m 2/g, and the average pore volume is about 0.5cm 3/g. Compared with the active carbon in the market, the specific surface area of the prior patent is not obviously improved. The biological porous carbon prepared by the process has an ultra-micro-medium spanning pore structure and an ultra-high specific surface area, the specific surface area and the pore volume respectively reach 3149m 2/g and 1.76cm 3/g, which are 109.9% and 252% of the active carbon on the market and 102.7% of the maximum specific surface area of the current patent, and the biological porous carbon has great economic and social benefits.
(3) The super micro-meso-macroporous spanning pore structure and the super high specific surface area of the biological porous carbon provide more adsorption sites for the VOCs adsorbate, reduce the diffusion resistance of the VOCs, and enable the VOCs to be rapidly diffused and desorbed. Wherein, the introduced metallic elements such as iron element and the like endow the biochar with catalytic capability and adsorption sites; the introduced quadrupole moment effect of rich nonmetallic elements N, P and the like promotes the PBC to have higher affinity to VOCs, and the synergistic effect of metal and nonmetal ensures that the biochar has higher adsorption capacity to the VOCs represented by acetone and n-hexane vapor, which respectively reach 1046mg/g and 760mg/g, and the adsorption performance is improved by approximately 138% and 132%. In addition, the invention can use simple and low-consumption desorption operation to carry out repeated adsorption, and after 5 adsorption-desorption cycles, the PBC adsorption quantity keeps 97% of the initial adsorption capacity, so that the invention has more excellent recoverability. The biological porous carbon prepared by the invention has excellent performance, is beneficial to solving the embarrassment of poor adsorption capacity, low efficiency, high energy consumption and short service life of the traditional activated carbon, is beneficial to improving the energy utilization rate, and has extremely strong economic benefit and sustainability.
(4) Compared with the traditional single mixing methods such as physical grinding mixing, dipping mixing, stirring mixing and the like, the ultrasonic dipping mixing in the preparation method can enable the biochar to be mixed with the etchant and the phosphide more fully, and has higher efficiency. Compared with the traditional KOH pyrolysis activation, hydrothermal activation and other activation methods, the preparation method has the advantages that the preparation efficiency is higher, and the activation is more thorough. This patent make full use of charcoal of green discarded object preparation can reach the purpose of solid carbon, emission reduction, and the prospect of helping hand "double carbon" satisfies the situational demand of current country to carbon emission.
Drawings
FIG. 1 is an SEM image of PBC and PBC-0.3;
FIG. 2 is an infrared spectrogram of PBC and PBC-0.3;
FIG. 3 shows the vapor adsorption of (a) acetone and (b) n-hexane by PBC and PBC-X at 30deg.C;
FIG. 4 shows five successive adsorbtions of n-hexane at 30℃on PBC and PBC-0.3.
FIG. 5 is a flowchart of PBC-0.3 preparation process.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention.
Example 1
Firstly, cleaning pulp of a commercial watermelon waste, performing washing, drying and crushing pretreatment, performing ultrasonic dipping in 0.3M ferric nitrate solution for 5 hours, then placing in a vacuum atmosphere sintering furnace for carbonization and activation, heating at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, maintaining the temperature at 400 ℃ for 1 hour, cooling to room temperature, and taking out to obtain watermelon peel carbonized material PC; watermelon peel carbonized material PC: potassium hydroxide: melamine phosphate is weighed in a mass ratio of 1:3:0.1, potassium hydroxide is weighed in a mass ratio of 1:10, soaking and mixing PC in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH; melamine phosphate was added at 1:10, soaking and mixing PC-OH in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH-P-0.1; placing PC-OH-P-0.1 in a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 800 ℃ for activation for 1h at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PAC-0.1 of watermelon peel; washing PAC-0.1 with 2mol/L hydrochloric acid solution with pH of 4, dissolving thoroughly to remove residual potassium hydroxide and other impurities, washing with deionized water until the pH value of the washing water becomes neutral, and vacuum drying at 105 ℃ until constant weight is maintained to prepare the multi-stage activated waste watermelon peel biological porous carbon named as PBC-0.1.
Example 2
Firstly, cleaning pulp of a commercial watermelon waste, performing washing, drying and crushing pretreatment, performing ultrasonic dipping in 0.3M ferric nitrate solution for 5 hours, then placing in a vacuum atmosphere sintering furnace for carbonization and activation, heating at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, maintaining the temperature at 400 ℃ for 1 hour, cooling to room temperature, and taking out to obtain watermelon peel carbonized material PC; PC: potassium hydroxide: melamine phosphate is weighed in a mass ratio of 1:3:0.2, potassium hydroxide is weighed in a mass ratio of 1:10, soaking and mixing PC in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH; melamine phosphate was added at 1:10, soaking and mixing PC-OH in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH-P-0.2; placing PC-OH-P-0.2 in a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 800 ℃ for activation for 1h at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PAC-0.2 of watermelon peel; washing PAC-0.2 with 2mol/L hydrochloric acid solution with pH of 4, dissolving thoroughly to remove residual potassium hydroxide and other impurities, washing with deionized water until the pH value of the washing water becomes neutral, and vacuum drying at 105 ℃ until constant weight is maintained to prepare the multi-stage activated waste watermelon peel biological porous carbon named as PBC-0.2.
Example 3
Firstly, cleaning pulp of a commercial watermelon waste, performing washing, drying and crushing pretreatment, performing ultrasonic dipping in 0.3M ferric nitrate solution for 5 hours, then placing in a vacuum atmosphere sintering furnace for carbonization and activation, heating at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, maintaining the temperature at 400 ℃ for 1 hour, cooling to room temperature, and taking out to obtain watermelon peel carbonized material PC; PC: potassium hydroxide: melamine phosphate is weighed in a mass ratio of 1:3:0.3, potassium hydroxide is weighed in a mass ratio of 1:10, soaking and mixing PC in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH; melamine phosphate was added at 1:10, soaking and mixing PC-OH in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH-P-0.3; placing PC-OH-P-0.3 in a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 800 ℃ for activation for 1h at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PAC-0.3 of watermelon peel; washing PAC-0.3 with 2mol/L hydrochloric acid solution with pH of 4, dissolving thoroughly to remove residual potassium hydroxide and other impurities, washing with deionized water until the pH value of the washing water becomes neutral, and vacuum drying at 105 ℃ until constant weight is maintained to prepare the multi-stage activated waste watermelon peel biological porous carbon named as PBC-0.3.
Example 4
Firstly, cleaning pulp of a commercial watermelon waste, performing washing, drying and crushing pretreatment, performing ultrasonic dipping in 0.3M ferric nitrate solution for 5 hours, then placing in a vacuum atmosphere sintering furnace for carbonization and activation, heating at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, maintaining the temperature at 400 ℃ for 1 hour, cooling to room temperature, and taking out to obtain watermelon peel carbonized material PC; PC: potassium hydroxide: melamine phosphate is weighed in a mass ratio of 1:3:0.4, potassium hydroxide is weighed in a mass ratio of 1:10, soaking and mixing PC in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH; melamine phosphate was added at 1:10, soaking and mixing PC-OH in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH-P-0.4; placing PC-OH-P-0.4 in a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 800 ℃ for activation for 1h at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PAC-0.4 of watermelon peel; washing PAC-0.4 with 2mol/L hydrochloric acid solution with pH of 4, dissolving thoroughly to remove residual potassium hydroxide and other impurities, washing with deionized water until the pH value of the washing water becomes neutral, and vacuum drying at 105 ℃ until constant weight is maintained to prepare the multi-stage activated waste watermelon peel biological porous carbon named as PBC-0.4.
Comparative example 1 (direct carbonization of watermelon peel, unmodified)
The preparation method comprises the steps of firstly removing pulp from the waste watermelon peel sold in the market, washing, drying, crushing, pretreating, placing in a vacuum atmosphere sintering furnace for carbonization and activation, heating at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, maintaining the temperature at 800 ℃ for activation for 1h, and taking out when the temperature of a sample is reduced to room temperature, thus obtaining the activated carbon PAC of the watermelon peel.
Comparative example 2 (non-phosphorated)
Firstly, cleaning pulp of a commercial watermelon waste, performing washing, drying and crushing pretreatment, performing ultrasonic dipping in 0.3M ferric nitrate solution for 5 hours, then placing in a vacuum atmosphere sintering furnace for carbonization and activation, heating at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, maintaining the temperature at 400 ℃ for 1 hour, cooling to room temperature, and taking out to obtain watermelon peel carbonized material PC; PC: potassium hydroxide was weighed in a mass ratio of 1:3, potassium hydroxide in a ratio of 1:10, soaking and mixing PC in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH; placing PC-OH in a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 800 ℃ for activation for 1h at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PAC of watermelon peel; washing PAC with 2mol/L hydrochloric acid solution with pH of 4, dissolving thoroughly to remove residual potassium hydroxide and other impurities, washing with deionized water until the pH value of the washing water becomes neutral, and vacuum drying at 105 ℃ until constant weight is maintained to prepare the multi-stage activated waste watermelon peel biological porous carbon, which is named as PBC.
Comparative example 3 (without phosphide and potassium hydroxide)
The preparation method comprises the steps of firstly removing pulp from the waste watermelon peel, washing, drying, crushing, pretreating, ultrasonically soaking in 0.3M ferric nitrate solution for 5 hours, then placing in a vacuum atmosphere sintering furnace for carbonization and activation, heating at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, maintaining the temperature at 800 ℃ for activation for 1 hour, and taking out when the temperature of a sample is reduced to room temperature, thus obtaining the activated carbon PACP of the watermelon peel.
Comparative example 4 (without added metal salt)
The preparation method comprises the steps of firstly removing pulp from the waste watermelon peel sold in the market, performing pretreatment by washing, drying and crushing, then placing the pulp in a vacuum atmosphere sintering furnace for carbonization and activation, heating the pulp in a high-purity nitrogen atmosphere at a heating rate of 5 ℃/min, maintaining the temperature at 400 ℃ for 1h, cooling the pulp to room temperature, and taking out the pulp to obtain watermelon peel carbonized material PCP; PCP: potassium hydroxide: melamine phosphate is weighed in a mass ratio of 1:3:0.3, potassium hydroxide is weighed in a mass ratio of 1:10, soaking and mixing PCP in deionized water, performing ultrasonic treatment for 30min, taking out, performing vacuum drying treatment at 105 ℃ until constant weight is maintained, taking out, and grinding uniformly to obtain PCP-OH; melamine phosphate was added at 1:10, soaking and mixing PCP-OH in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PCP-OH-P-0.3; placing PCP-OH-P-0.3 in a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 800 ℃ for activation for 1h at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PACP-0.3 of watermelon peel; and (3) cleaning PACP-0.3 with a hydrochloric acid solution with the concentration of 2mol/L, fully dissolving and removing impurities such as residual potassium hydroxide, cleaning with deionized water until the pH value of the washing water becomes neutral, and then carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, so as to prepare the multi-stage activated waste watermelon peel biological porous carbon, which is named as PBCP-0.3.
Comparative example 5 (changing phosphide to sodium Hydrogen phosphate)
Firstly, cleaning pulp of a commercial watermelon waste, performing washing, drying and crushing pretreatment, performing ultrasonic dipping in 0.3M ferric nitrate solution for 5 hours, then placing in a vacuum atmosphere sintering furnace for carbonization and activation, heating at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, maintaining the temperature at 400 ℃ for 1 hour, cooling to room temperature, and taking out to obtain watermelon peel carbonized material PC; PC: potassium hydroxide: sodium hydrogen phosphate is weighed according to the mass ratio of 1:3:0.3, and potassium hydroxide is weighed according to the mass ratio of 1:10, soaking and mixing PC in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH; sodium hydrogen phosphate at 1:10, soaking and mixing PC-OH in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH-PN-0.3; placing PC-OH-PN-0.3 in a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 800 ℃ for activation for 1h at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, and taking out when the temperature of a sample is reduced to room temperature to obtain watermelon peel activated carbon PACN-0.4; washing PACN-0.3 with 2mol/L hydrochloric acid solution with pH of 4, dissolving thoroughly to remove residual potassium hydroxide and other impurities, washing with deionized water until the pH value of the washing water becomes neutral, and vacuum drying at 105deg.C until constant weight is maintained to obtain multi-stage activated waste watermelon peel biological porous carbon, designated PBCN-0.3.
Comparative example 6 (modification of carbon Source sequence: adding Metal salt first and then phosphide and Potassium hydroxide)
The preparation method comprises the steps of firstly removing pulp from waste watermelon peel sold in the market, performing pretreatment by washing, drying and crushing, then placing the pulp in a vacuum atmosphere sintering furnace for carbonization and activation, heating the pulp in a high-purity nitrogen atmosphere at a heating rate of 5 ℃/min, maintaining the temperature at 400 ℃ for 1h, cooling the pulp to room temperature, and taking out the pulp to obtain watermelon peel carbonized material PC; PC: potassium hydroxide: melamine phosphate is weighed in a mass ratio of 1:3:0.3, potassium hydroxide is weighed in a mass ratio of 1:10, soaking and mixing PC in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until constant weight is maintained, taking out, and grinding uniformly to obtain PC-OH; melamine phosphate was added at 1:10, soaking and mixing PC-OH in deionized water, carrying out ultrasonic treatment for 30min, taking out, carrying out vacuum drying treatment at 105 ℃ until the constant weight is maintained, taking out and grinding uniformly to obtain PC-OH-P-0.3; placing PC-OH-P-0.3 in a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 800 ℃ for activation for 1h at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PAC-0.3 of watermelon peel; placing PC-OH-P-0.3 into an ultrasonic dipping 0.3M ferric nitrate solution for 5h, placing into a vacuum atmosphere sintering furnace for pyrolysis activation, heating to 400 ℃ at a heating rate of 5 ℃/min under a high-purity nitrogen atmosphere for activation for 1h, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PAC-0.3-Fe of watermelon peel; washing PAC-0.3-Fe with 2mol/L hydrochloric acid solution, fully dissolving and removing impurities such as residual potassium hydroxide, washing with deionized water until the pH value of washing water becomes neutral, and vacuum drying at 105 ℃ until constant weight is maintained to prepare the multi-stage activated waste watermelon peel biological porous carbon named PBC-0.3-Fe.
SEM observations of morphology of example 3 and comparative examples 1-6 are made and FIG. 1 shows an SEM image of example 3 and comparative examples 1-6.
The PAC and PBC shown in the attached figure 1 mainly consist of large irregular blocky particles, the surface is rough and uneven, the porous structure of the PBC is richer. PBCP-0.3 consisted mainly of partially coarse bulk particles and partially smooth flakes, while PBCP-0.3 had more smooth flakes due to the following reasons: ① Ferric salt solutions that are well adhered to the surface and interior of PC produce iron (e.g., fe 0、Fe2O3、Fe3O4) of different forms in an inert atmosphere at about 400 ℃, but produce mainly lower valence Fe and Fe 0. During initial carbonization, the iron elements are adsorbed on the surface or pores of a PC structure in a physical way, and then react with rich hydroxyl and carboxyl groups of the fruit and vegetable peels at high temperature to form stable metal-carboxylate bonds; and, the iron element can be chemically bonded with the decomposition product of PC-phenolic compound, and stably anchored on the surface and in the pores of PC. In the subsequent mixing of PC with KOH and phosphide, lower valence Fe and Fe 0 will oxidize to Fe 2O3 and Fe 3O4,Fe2O3 and Fe 3O4 will give PC catalytic performance, raise redox reaction in secondary activation process, and form new adsorption sites on PBC surface to promote the adsorption capacity of PBC to n-hexane and acetone. ② KOH activation causes severe etching and modification of the surface. ③ The melamine phosphate generates part of H 3PO4 in the pyrolysis process and releases a large amount of gas so as to further generate an activation modification effect on the morphology of the PBC-0.3, thereby further optimizing the pore structure of the PBC-0.3.
Fourier infrared tests were performed on example 3 and comparative example 1, and fig. 2 shows infrared spectra of PBC and PBC-0.3.
As shown in fig. 2, the spectra trend was similar for PBC and PBC-0.3, the peak at 3441cm -1 was caused by O-H stretching vibration, and the peak at 1510cm -1 was caused by c=n, due to the pyrolysis crosslinking reaction of FR-MP rich N content with activated carbon. A sharp and intense peak was observed at 1100cm -1 for both PBC and PBC-0.3, which was attributed to the peak of C-C stretching vibration. Notably, PBC-0.3 exhibits a stronger radical character than PBC because P-O bond stretching vibrations are generated during pyrolysis of porous carbon at 1100cm -1 in addition to C-C stretching vibrations and FR-MP for PBC-0.3. FTIR spectroscopic results showed that FR-MP was successfully incorporated into the carbon backbone of activated carbon.
The specific surface area, the total pore volume, the micropore area and the adsorption amount of n-hexane of the bio-porous carbon prepared in examples 1 to 4 were measured and compared with comparative examples 1 to 6. The test sample is heated to (100-150) deg.c and held for (30-60) min before adsorption test to eliminate residual gas in the pores. After cooling to room temperature, the adsorption of n-hexane was achieved by bubbling. The measurement results are shown in Table 1.
TABLE 1 Performance test results of the composite materials prepared in examples 1-4 and comparative example
As can be seen from Table 1, the bio-porous carbon prepared in examples 1 to 4 has a large number of micropores. The specific surface area of PBC-X (x=0.1, 0.2, 0.3, 0.4) shows a tendency to increase and decrease with increasing mass ratio of melamine phosphate. Wherein PBC-0.3 shows the most excellent physical structure property, and the specific surface area and the pore volume reach 3149m 2/g and 1.76cm 3/g respectively. However, as the mass ratio reached 0.4, the specific surface area of PBC-0.4 began to slip down (2381 m 2/g). Comparing PBC-0.1 with PBC-0.4, it was found that the two samples had a similar specific surface area, but the total pore volume of PBC-0.4 was much greater than that of PBC-0.1 (1.60 cm 3/g>1.38cm3/g), due to the further etching of micropores formed by the induction of excess melamine phosphate addition, which was converted to mesopores. The results show that the addition of melamine phosphate helps to further optimize the pore structure of the activated carbon.
The bio-porous carbon prepared in examples 1 to 4 was tested for adsorption of acetone and n-hexane vapor by PBC at 30 c and compared with comparative examples 1 to 6. FIG. 3 shows the adsorption of (a) acetone and (b) n-hexane vapor at 30℃by PBC and PBC-X.
TABLE 2 adsorption of (a) acetone and (b) n-hexane vapor at 30℃by the composite materials prepared in examples 1-4 and comparative example
| Numbering device | Sample name | Acetone adsorption amount mg/g | Adsorption quantity mg/g of n-hexane |
| Example 1 | PBC-0.1 | 649 | 482 |
| Example 2 | PBC-0.2 | 807 | 674 |
| Example 3 | PBC-0.3 | 1046 | 760 |
| Example 4 | PBC-0.4 | 723 | 498 |
| Comparative example 1 | PAC | 336 | 129 |
| Comparative example 2 | PBC | 440 | 327 |
| Comparative example 3 | PACP | 597 | 463 |
| Comparative example 4 | PBCP-0.3 | 786 | 597 |
| Comparative example 5 | PBCN-0.3 | 942 | 751 |
| Comparative example 6 | PBC-0.3-Fe | 866 | 683 |
As shown in FIG. 3, the adsorption amounts of acetone and n-hexane vapor on PBC were relatively low, wherein the adsorption amounts of acetone and n-hexane vapor were 440mg/g and 327mg/g, respectively. After being modified by melamine phosphate, the adsorption capacity of the porous carbon to acetone and n-hexane vapor is obviously improved. Wherein, the adsorption capacity of PBC-0.3 to two adsorbents reaches the maximum value, which is 1046mg/g and 760mg/g respectively, and the adsorption performance is improved by approximately 138% and 132%. The result shows that the large specific surface area of PBC-0.3 provides more adsorption sites for the adsorbate, and improves the adsorption performance of the porous carbon on VOCs. Comparing the adsorption curves of PBC-X on acetone and n-hexane vapor, it is observed that the prepared PBC-X has larger adsorption quantity on acetone and reaches adsorption saturation more rapidly. This is because, on the one hand, the acetone molecules have smaller molecular dynamics diameters than n-hexane molecules, and the same pore canal pores can adsorb more acetone molecules. On the other hand, the smaller acetone molecules have smaller diffusion resistance, and can rapidly enter the pore canal through the mesopores of the porous carbon to realize adsorption. The melamine phosphate modified PBC-X exhibits the potential of an excellent adsorbent.
Five cycles of adsorption and desorption experiments were performed on n-hexane vapor at 30℃for example 3 and comparative example 1. FIG. 4 shows five successive adsorbtions of n-hexane at 30℃on PBC and PBC-0.3.
As shown in FIG. 4, the adsorption amounts of PBC and PBC-0.3 were slightly decreased after five adsorption-desorption cycles. But by comparison, the 5 th adsorption capacity of PBC-0.3 retained 97% of its initial adsorption capacity, while PBC retained only 94% of its initial adsorption capacity and required a longer desorption time. This is because the micro mesoporous channels of PBC-0.3 allow the adsorbate to be easily desorbed from the adsorption sites and released from the channels after the escaping thermal energy is captured. It can be seen that the prepared bio-porous carbon has more excellent recyclability.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.
Claims (9)
1. The preparation method of the multi-stage activated waste fruit and vegetable peel biological porous carbon is characterized by comprising the following steps of:
(1) Removing pulp from waste fruit and vegetable peels, washing, drying, crushing, pre-treating, ultrasonically soaking in 0.1-0.5M ferric salt solution for 4-10 h, then placing in a vacuum atmosphere sintering furnace, heating to 400-500 ℃ at 5-10 ℃/min in an atmosphere of N 2, maintaining for 1-3h, and taking out when the temperature of a sample is reduced to room temperature to obtain carbonized activated fruit and vegetable peel carbonized material PC;
(2) PC and an etchant are mixed according to the mass ratio of 1: fully mixing the components in the ratio of (1-5), and drying to obtain PC-OH;
(3) Fully mixing PC-OH with phosphide, and drying to obtain PC-OH-P;
(4) Placing PC-OH-P in a vacuum atmosphere sintering furnace for co-pyrolysis activation, and taking out when the temperature of a sample is reduced to room temperature to obtain activated carbon PAC of the fruit and vegetable peels;
(5) Washing PAC with hydrochloric acid solution, washing with deionized water until the pH value of washing water becomes neutral, and drying to prepare the multi-stage activated waste fruit and vegetable peel biological porous carbon PBC with ultrahigh specific surface area; the specific surface area of the porous carbon PBC is 2000-4000m 2/g, and the pore volume is 1.3-1.8 cm 3/g-1.
2. The method of claim 1, wherein the fruit and vegetable comprises at least one fruit and vegetable selected from the group consisting of watermelon, banana, dragon fruit, durian, cantaloupe, potato, and waste peel.
3. The method of claim 1, wherein the iron salt comprises at least one of ferrous sulfate and ferric nitrate.
4. The method of claim 1, wherein the etchant comprises at least one of potassium hydroxide, sodium hydroxide, phosphoric acid, potassium carbonate, and zinc chloride.
5. The preparation method according to claim 1, wherein the specific steps of thoroughly mixing and drying are as follows:
Firstly, dissolving an etchant or phosphide by deionized water, then slowly adding PC into the etchant solution or the PC-OH into the phosphide solution until the solution is fully soaked, and moving the solution into an ultrasonic container for ultrasonic treatment for 10-30min to fully mix the solution;
After being uniformly mixed, the mixture is dried in vacuum at 100-120 ℃ until the constant weight is maintained, and the mixture is taken out and uniformly ground when the temperature of the sample is reduced to room temperature.
6. The preparation method according to claim 1, wherein the phosphide comprises one of melamine phosphate, ammonium phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, and sodium hydrogen phosphate; the mass ratio of PC to phosphide is 1 (0.1-0.4).
7. The method according to claim 1, wherein the pyrolysis activation conditions of the vacuum atmosphere sintering furnace in the step (4) are: heating to 700-1000deg.C at 5-10deg.C/min in N 2 atmosphere and maintaining for 1-3 hr.
8. The use of the multi-stage activated waste fruit and vegetable peel biochar prepared by the method according to any one of claims 1 to 7, wherein the biochar is used for the adsorption of VOCs.
9. The use of the multi-stage activated waste fruit and vegetable peel biochar prepared by the method according to any one of claims 1 to 7, wherein the biochar is used for adsorption of acetone and/or n-hexane.
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