Nano-diamond prepared by using plant fiber as raw material and method thereof
Technical Field
The invention belongs to the technical field of diamond preparation, and particularly relates to a nano diamond prepared by using plant fibers as raw materials and a preparation method thereof.
Background
Carbon materials have been extensively studied in the past few decades for their high thermal stability and mechanical properties. The nanodiamond is sp3The hybridized carbon nano-particles are allotropes with graphite, graphene, carbon nano-tubes, fullerene and the like. The nano-diamond has attracted attention due to excellent mechanical and optical properties, high specific surface area, adjustable surface structure and the like, and has wide application prospects in the fields of polishing, lubrication, biological calibration, drug delivery, quantum computation, biosensors and the like. However, natural diamond reserves are rare, greatly limiting its large-scale application. Currently, nanodiamonds are mainly prepared by methods such as explosion, Chemical Vapor Deposition (CVD), high temperature and high pressure grinding, plasma high pressure impact, etc., but these methods are harsh and require an extremely high temperature and pressure environment, or expensive gaseous/chemical precursors. Therefore, the development of a method which is simple to operate, safe, effective and environment-friendly for preparing the nano-diamond is of great significance.
The plant fiber is the most abundant renewable resource in nature, and has the advantages of low price, easy obtainment, environmental protection, biodegradability and the like. Plant fibers mainly comprise cellulose, hemicellulose, lignin and other substances, and are important sources of raw materials in the pulping and papermaking industry. The data show that the global pulp yield in 2018 is about 1.84 million tons, and simultaneously about 7000 million tons of lignin are generated, wherein only about 2 percent of the lignin recovers heat energy through combustion, replaces stone materials, and therefore, the characteristic of low added value of plant fiber products is also caused.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a nano-diamond prepared by using plant fibers as raw materials and a method thereof. The problems of harsh preparation conditions and expensive raw materials of the nano-diamond in the prior art are solved.
The purpose of the invention is realized by the following technical scheme:
a method for preparing nano diamond by taking plant fiber as a raw material comprises the following steps:
(1) adding plant fiber raw materials into a ball mill, and performing ball milling, crushing and mixing to obtain plant fiber powder;
(2) tabletting the plant fiber powder to obtain flaky plant fibers; preferably, the pressure of the tabletting treatment is 5-10MPa, and the thickness of the flaky plant fiber is 0.2-2 mm. Specifically, according to the actual requirement, a proper pressure is selected for tabletting treatment, such as 5Mpa, 7Mpa, 8Mpa or 10 Mpa; the thickness of the flaky plant fiber can be adjusted properly, for example, the thickness can be selected to be 0.2mm, 0.8mm, 1mm, 1.4mm, 1.8mm or 2 mm; the tablet pressing treatment can be carried out by selecting different types of tablet presses, and the shape of the flaky plant fiber can be a round piece shape or a square shape and the like.
(3) The plant fiber membrane is placed on a workbench controlled by a computer program, a femtosecond laser is used for carrying out laser radiation on the plant fiber membrane at normal temperature and normal pressure, and under the action of laser irradiation, the plant fiber is carbonized and simultaneously undergoes carbon phase change to generate the nano diamond. Further, the laser power of the femtosecond laser is 100-1000 mW, the laser radiation time is 1-60 min, and the operating speed of the workbench is 1-100 mm/s. Specifically, the laser power of the femtosecond laser can be 100mW, 500mW, 800mW or 1000mW, the laser radiation time is 1min, 10min, 30min, 45min or 60min, and the operating speed of the workbench is 1mm/s, 30mm/s, 60mm/s, 80mm/s or 100 mm/s.
Preferably, in the step (1), the plant fiber raw material is lignin or a mixture of lignin and cellulose. When the nano-diamond is prepared by taking the lignin as the raw material, the lignin is mainly in an aromatic structure and has strong hydrophobicity, and no connecting sites exist among lignin molecules, so that the lignin cannot be prepared into a film shape by a film forming method, and the lignin is pressed into a sheet shape by a sheet pressing method, so that the laser irradiation is convenient to perform subsequently. When the mixture of lignin and cellulose is used as a raw material to prepare the nano-diamond, because cellulose molecules contain a large number of hydrogen-containing groups such as hydroxyl and the like and oxygen-containing groups such as carbonyl and the like, certain hydrogen bonding effect exists between the lignin and the cellulose, namely the cellulose can play a role similar to a binder, the binding property between the lignin molecules is enhanced, the prepared sheet material has better stability, and the subsequent laser irradiation step is facilitated. In addition, cellulose can generate CO and H after laser irradiation2、CO2Isodecomposing gas of CO and H2The gas has reducing property, has catalytic effect on reduction of carbon, and can promote generation of diamond.
More preferably, the lignin is at least one of nano lignin, needle lignin, broad-leaf lignin, herbaceous lignin, alkaline lignin and sodium lignosulfonate; the cellulose is nano-cellulose or paper pulp.
Further preferably, the mechanical crushing treatment is ball milling treatment, the rotating speed of the ball mill during the ball milling treatment is 200-400r/min, and the ball milling time is 10-30 h. In specific implementation, the rotating speed of the ball mill can be 200r/min, 250r/min, 300r/min, 360r/min or 400r/min, and the ball milling time can be 10h, 15h, 18h, 25h or 30 h.
Another object of the present invention is to provide the nanodiamond prepared by the above method.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, after the plant fiber is made into the sheet-shaped plant fiber, the plant fiber is carbonized and simultaneously subjected to carbon phase change under the laser irradiation action of the femtosecond laser, so that the nano diamond is generated. The method has the advantages of cheap and easily-obtained raw materials, simple synthesis method, mild conditions, high efficiency, simple operation and the like. The prepared nano diamond has the granularity within 50nm, and has high application value in the fields of micro supercapacitors, sensors, wastewater treatment and the like.
Drawings
Fig. 1 is a transmission electron micrograph of the nanodiamond in example 1.
Fig. 2 is a high resolution transmission electron micrograph of the nanodiamond of example 1.
FIG. 3 is a transmission electron micrograph of nanodiamonds in example 2.
Fig. 4 is a high resolution transmission electron micrograph of the nanodiamond of example 2.
Detailed Description
The invention is further illustrated below with reference to specific embodiments and the accompanying drawings. It should be noted that the following embodiments are illustrative, and are not intended to limit the scope of the present invention. After reading the present disclosure, various changes or modifications may be made by those skilled in the art, and these equivalents also fall within the scope of the present disclosure.
It should be noted that various raw materials and reagents used in the following examples are commercially available products, and detailed description thereof will not be provided herein.
Example 1
Putting the pine lignin into a ball mill for ball milling for 18h, setting the rotating speed of the ball mill to be 360r/min, resting for 0.5h every 1h, and taking out after the ball milling is finished to obtain lignin powder. 0.08g of lignin powder was added to a tablet press and pressed under a pressure of 10MPa to obtain a lignin pellet having a diameter of 13mm and a thickness of about 1.0 mm. Placing the disc-shaped lignin on a workbench controlled by a computer program, carrying out laser radiation at normal temperature and normal pressure by using a femtosecond laser, and converting the radiated lignin into the nano-diamond. Wherein the laser wavelength of the femtosecond laser is 1030nm, the laser frequency is 120kHz, and the pulse time is 150 fs; the radiation conditions are that the laser power is 1000mW, the radiation time is 30min, and the operating speed of the workbench is 4 mm/s.
The results of analyzing the microstructure of the nanodiamond using a transmission electron microscope are shown in fig. 1 and 2, in which: fig. 1 is a transmission electron microscope image of the prepared nano-diamond, and it can be seen from fig. 1 that the nano-diamond prepared by the invention has uniform grain size, which is below 50 nm. Fig. 2 is a high resolution transmission electron micrograph of the nanodiamond, from which fig. 2 it can be seen that the apparent nanodiamond lattice fringes, calculated interplanar spacing of 0.269nm, correspond to the (200) orientation of the nanodiamond. Combining fig. 1 and 2, it is shown that the method is effective in producing nanodiamonds.
Example 2
The purchased nano-cellulose is nano-lignin dispersion liquid with the concentration of 3%, 100g of the nano-lignin dispersion liquid is weighed (namely the absolute dry weight of the nano-cellulose is 3g), then the nano-lignin is mixed with 7g of pine lignin and added into a ball milling tank, the ball milling tank is placed into a ball mill for ball milling for 18h, the rotating speed of the ball mill is set to 360r/min, the ball milling tank is rested for 0.5h every 1h, the nano-cellulose is taken out after the ball milling is finished, and the nano-cellulose is placed into a freeze dryer at the temperature of minus 40 ℃ for drying for 72h, so that the cellulose/. 0.08g of the cellulose/lignin complex was added to a tablet press and pressed at a pressure of 10MPa to give a disc-like cellulose/lignin complex having a diameter of 13mm and a thickness of about 0.9 mm. Placing the disc-shaped cellulose/lignin compound on a workbench controlled by a computer program, carrying out laser radiation at normal temperature and normal pressure by using a femtosecond laser, and converting the irradiated raw material into the nano diamond. Wherein the laser wavelength of the femtosecond laser is 1030nm, the laser frequency is 120kHz, and the pulse time is 150 fs; the radiation conditions are that the laser power is 700mW, the radiation time is 30min, and the operating speed of the workbench is 5 mm/s.
The results of analyzing the microstructure of the nanodiamond using a transmission electron microscope are shown in fig. 3 and 4, in which: fig. 3 is a transmission electron microscope image of the prepared nano-diamond, and it can be seen from fig. 1 that the nano-diamond prepared by the present invention has uniform grain size, all of which are below 50 nm. Fig. 4 is a high resolution transmission electron micrograph of nanodiamond, from which fig. 4 it can be seen that the apparent nanodiamond lattice fringes, calculated interplanar spacings of 0.27nm and 0.31nm, correspond to the (200) and (111) orientations of nanodiamond, respectively. Combining fig. 3 and 4, it is shown that the method effectively produces nanodiamonds. Compared with the embodiment 1, after the cellulose is added into the pine lignin, the laser power required for preparing the nano diamond is lower, and the energy consumption can be reduced.
Example 3
30g of paper pulp is taken and torn into sheets, and then the sheets are added into 1500mL of deionized water to be soaked for 6 h. And adding the soaked paper pulp and deionized water into a fluffer for fluffing for 5min, repeatedly filtering fluffing liquid for 3 times, and preparing the fluffed paper pulp into cellulose dispersion liquid with the concentration of 3 wt.%. Putting 7g of cellulose dispersion liquid with the absolute dry weight and 3g of eucalyptus lignin into a ball mill for ball milling for 18h, setting the rotating speed of the ball mill to be 360r/min, resting for 0.5h every 1h, taking out the mixture after the ball milling is finished, and placing the mixture in a freeze dryer at the temperature of minus 40 ℃ for drying for 72h to obtain the cellulose/lignin compound. 0.08g of the cellulose/lignin complex was added to a tablet press and pressed at a pressure of 10MPa to give a disc-like cellulose/lignin complex having a diameter of 13mm and a thickness of about 0.9 mm. Placing the disc-shaped cellulose/lignin compound on a workbench controlled by a computer program, carrying out laser radiation at normal temperature and normal pressure by using a femtosecond laser, and converting the irradiated raw material into the nano diamond. Wherein the laser wavelength of the femtosecond laser is 1030nm, the laser frequency is 120kHz, and the pulse time is 150 fs; the radiation conditions are that the laser power is 150mW, the radiation time is 60min, and the operating speed of the workbench is 90 mm/s.
Example 4
30g of paper pulp is taken and torn into sheets, and then the sheets are added into 1500mL of deionized water to be soaked for 6 h. And adding the soaked paper pulp and deionized water into a fluffer for fluffing for 5min, repeatedly filtering fluffing liquid for 3 times, and preparing the fluffed paper pulp into cellulose dispersion liquid with the concentration of 3 wt.%. And (3) putting 5g of cellulose dispersion liquid and 5g of pine lignin into a ball mill for ball milling for 18h, setting the rotating speed of the ball mill to be 360r/min, resting for 0.5h every 1h, taking out the mixture after the ball milling is finished, and drying for 72h in a freeze dryer at the temperature of-40 ℃ to obtain the cellulose/lignin compound. 0.08g of the cellulose/lignin complex was added to a tablet press and pressed at a pressure of 10MPa to give a disc-like cellulose/lignin complex having a diameter of 13mm and a thickness of about 0.9 mm. Placing the disc-shaped cellulose/lignin compound on a workbench controlled by a computer program, carrying out laser radiation at normal temperature and normal pressure by using a femtosecond laser, and converting the irradiated raw material into the nano diamond. Wherein the laser wavelength of the femtosecond laser is 1030nm, the laser frequency is 120kHz, and the pulse time is 150 fs; the irradiation conditions are that the laser power is 450mW, the irradiation time is 35min, and the operating speed of the workbench is 30 mm/s.
Example 5
Placing 6g of nano cellulose dispersion liquid with the absolute dry weight of 3 wt.% and 4g of eucalyptus lignin into a ball mill for ball milling for 12 hours, setting the rotating speed of the ball mill to be 360r/min, resting for 0.5 hour every 1 hour of work, taking out after the ball milling is finished, and placing the ball mill in a freeze dryer at the temperature of minus 40 ℃ for drying for 72 hours to obtain the cellulose/lignin compound. 0.08g of the cellulose/lignin complex was added to a tablet press and pressed at a pressure of 10MPa to give a disc-like cellulose/lignin complex having a diameter of 13mm and a thickness of about 0.9 mm. Placing the disc-shaped cellulose/lignin compound on a workbench controlled by a computer program, carrying out laser radiation at normal temperature and normal pressure by using a femtosecond laser, and converting the irradiated raw material into the nano diamond. Wherein the laser wavelength of the femtosecond laser is 1030nm, the laser frequency is 120kHz, and the pulse time is 150 fs; the radiation conditions are that the laser power is 300mW, the radiation time is 30min, and the operating speed of the workbench is 60 mm/s.
Example 6
Placing the nano cellulose dispersion liquid with the absolute dry weight of 2g and the concentration of 3 wt.% and 8g of eucalyptus lignin into a ball mill for ball milling for 12 hours, setting the rotating speed of the ball mill to be 360r/min, resting for 0.5 hour every 1 hour of work, taking out after the ball milling is finished, and placing the ball mill in a freeze dryer at the temperature of minus 40 ℃ for drying for 72 hours to obtain the cellulose/lignin compound. 0.08g of the cellulose/lignin complex was added to a tablet press and pressed at a pressure of 10MPa to give a disc-like cellulose/lignin complex having a diameter of 13mm and a thickness of about 0.9 mm. Placing the disc-shaped cellulose/lignin compound on a workbench controlled by a computer program, carrying out laser radiation at normal temperature and normal pressure by using a femtosecond laser, and converting the irradiated raw material into the nano diamond. Wherein the laser wavelength of the femtosecond laser is 1030nm, the laser frequency is 120kHz, and the pulse time is 150 fs; the radiation conditions are that the laser power is 900mW, the radiation time is 30min, and the operating speed of the workbench is 10 mm/s.