Zinc nitrate system solid phase preparation nano-zinc oxide.

Abstract: Zinc nitrate and ammonium bicarbonate were used as raw materials to directly synthesize nano-zinc oxide with an average particle size of 40 nm by room temperature solid phase method, and the crystal type and particle appearance of zinc oxide obtained were characterized by X-ray diffraction instrument (XRD) and scanning electron microscope (SEM). The results show that the increase of calcination temperature and calcination time will increase the particle size of nano-zinc oxide, but it has little effect on the shape of zinc oxide, and the spherical structure is obtained.0 Introduction
nNO has a high chemical stability, thermal stability, non-migration, tasteless, non-toxic, non-irritating, cheap, safe to use, so it is the inorgestration anti-UV agent of choice . Using nano ZnO's excellent anti-UV function, nano ZnO can be added to outdoor coatings to improve the anti-aging properties of coatings, improve coating mascology and other performance indicators; Greatly improve the toughness index of plastics, nano ZnO add human fiber can be made into anti-UV functional fabric products, used in the production of parasols, awnings, anti-UV shirts, etc. , nano ZnO has been widely used in sunscreen cosmetics. Therefore, nano ZnO as an anti-UV functional powder has a wide range of market prospects. Nano-zinc oxide is a high-tech material found in recent years, because its particle size is smaller than the surface area, so it has obvious surface and interface effect, quantum size effect, volume effect and macro quantum channel effect and high dispersion, so that nano-zinc oxide as a new functional material, in magnetism, light, electricity, sensitivity, antibacterial disinfection, ultraviolet shielding and other aspects of ordinary zinc oxide products do not have special properties and uses.preparation methods for nano-zinc oxide include chemical and physical methods. Chemical method is a method by which an atom (or molecule) becomes nucleus and grows into nanoparticles by controlling the reaction conditions. Common preparation methods include uniform precipitation, direct precipitation, hydrothermal synthesis, sol-gel and template preparation. In addition, solid-phase grinding is also a quick and easy synthesis of nano-zinc oxide method, the study shows that the 1:1 (molar ratio) of oxalic acid and zinc dishydrated acetic acid, after grinding 30min drying, and then the pre-drive hydrated zinc hydrate at 460 degrees C thermal decomposition to obtain the average particle size of 20nm zinc oxide. The precipitation agent added by the uniform precipitation method will slowly generate the sediment in the whole solution through chemical reaction, solve the problem of local unevenness of the sediment caused by the direct addition of the precipitation agent, is the most commonly used preparation method, the product is high purity, the process is simple, but the reaction time is long and the reaction process is complex. Direct precipitation method is in the soluble zinc salt solution to add precipitation agent, the generation of another insoluble in water zinc salt or zinc alkali salt, zinc hydroxide, etc. , by filtration, washing, drying, roasting and other methods to obtain nano-zinc oxide, is also a more commonly used preparation method, this method is simple to operate, low requirements for equipment, low cost, but the dispersion of particles is poor, easy to reunite, difficult to remove anions. In a specially manufactured closed reaction container, the aqueous solution as the reaction medium, by heating the reaction container, and then create a high temperature and high pressure reaction environment, so that the usually insoluble or insoluble substance dissolved and recrystrystaled method is hydrothermal method, the method obtained by the product purity is high, uniform size, no reunion, low cost, but the equipment requirements, preparation conditions are harsh, easy to waste. Sol-gel method is inorganic salt or metal alcohol salt as the pre-body, by hydrolytic condensation process gradually glued, and then sintered treatment to obtain nano-powder, this method has a high purity, composition control, narrow size distribution range, small size and so on, but high cost, by the influence of metal alcohol salt is greater. Template preparation method is the use of physical or chemical methods to deposit the relevant materials into the hole or surface of the template, and then remove the template, to obtain a template tissue shape and size of nanomaterials method, template legal preparation of materials because of the reproduction of the micro-fine porous structure of biological templates, so it is widely used in the field of gas-sensitive sensors, the advantages of the method is size and appearance control, wide application, but the scale of production is small, crystalline difficult to control. Physical method is through the medium and materials between each other grinding, impact, preparation of nanoparticles method, common mechanical crushing method, deep plastic deformation method, but because of the physical legal system prepared material nanoscale and purity is low, so the degree of application is not high.the purpose of this paper is to provide a method of preparing nano-zinc oxide using solid-phase legal system. And the use of a relatively simple manual grinding, through the solid phase legal system prepared a good dispersion of the ball-like nano-scale zinc oxide. In this paper, the solid phase process conditions are simple, low cost, low requirements for equipment, green environmental protection and zinc oxide production, and the operating procedures are continuously adjustable, easy to control the experimental process, so easy to industrial production. The method is based on alkaline zinc carbonate as the pre-drive, and the spqueer nanoscale zinc oxide with good dispersion can be prepared by adjusting the experimental parameters.1 experimental part
1.1 raw materialsused in zinc nitrate, ammonium bicarbonate are pure raw materials for analysis, water for deionized water.
1.2 nanometer zinc oxide preparation . Zinc oxide is a simple and controllable synthesis method of zinc pre-body (alkaline zinc carbonate) first obtained by ball grinding or manual grinding of zinc salts (e.g. zinc nitrate, zinc nitrate) and ammonium bicarbonate through ball grinding, and then calcined at high temperatures to obtain zinc oxide. The solid phase method used in this paper is to prepare the nanoscale zinc oxide powder with good dispersion quickly and easily by hand grinding. The method of preparing zinc oxide mainly includes the following two steps:
5Zn (NO3) 2.6H2O,10NH4HCO3Zn5 (CO3)2 (OH) 6 plus 10NH4NO3 plus 8CO2 plus 32H2O (1)
ZZ n5 (CO3)2 (OH) 6 to 5ZnO plus 2CO2 plus 3H2O (2)reaction (1) is the process of forming alkaline zinc carbonate prelords during grinding;5.9498g zinc nitrate (0.02mol) and 3.1624g ammonium bicarbonate (0.04mol) in ceramic research, directly hand-grinding solid mixture 30min-90min When grinding, try to turn in the same direction (clockwise or counterclockwise); after the reaction, transfer the mixture from the ceramic research to a 250mL centrifugal bottle, add 100mL-150mL of deionized water, stir the suspension 3min with a glass rod -5min, then centrifugal suspension, filtration, continue to add deionized water, repeat washing and centrifugation steps 3 times; When studying the effect of different calcination temperatures on zinc oxide particle size, crystal type and particle shape, the calcination time was 90min, and the pre-driven body was placed at different temperatures (300 O, 350 O, 400 C and 450 O). When studying the effects of different calcination times on zinc oxide particle size, crystal type and particle shape, the calcination temperature was maintained at 350 degrees C, and the pre-excisive body was calcined at different times (60min, 90min, 120min and 150min);1.3 nanometer zinc oxide is characterized bydetection using an X-ray diffraction instrument (XRD) and a scanning electron microscope (SEM) to analyze the crystal shape and appearance of the resulting zinc oxide, and XRD is used to detect the crystal type of the alkaline zinc carbonate preconditory to determine the molecular form of the preconditory.2 Results and discussion of the effect of
2.1 calcination temperature on zinc oxide crystal type and particle morphological appearance XRD testing of the obtained pre-bodies, as shown in Figure 1, no diffraction peaks of other reactants and generators were found, only diffraction peaks of alkaline zinc carbonate, the results showed that the pre-drives were alkaline zinc carbonate, and the chemical type was Zn5 (CO3) 2 (OH)6;
XRD detection of zinc oxide powders at different calcination temperatures, as shown in Figure 2, zinc oxide in the map is a single crystalline type, so the crystal index is identified, the D value marked on the right side of the map is calculated by the Xiele formula to obtain the average particle size of zinc oxide powder. The results showed that calcination temperature significantly affected the particle size of zinc oxide, but it had no significant effect on its crystalline type, and it was all six-way zinc fiber structure. The particle size increased from 300 to 450 degrees C, and the particle size gradually increased from 38.5nm to 42.2nm. The results of SEM show that zinc oxide is a typical speral structure, with uniform dispersion and small particle size, as shown in Figure 3 (a) (b). It can be seen that in order to obtain zinc oxide with a smaller particle size, the calcination temperature needs to be set to 300 degrees C.
2.2 Effect of calcination time on zinc oxide crystal type and particle appearance
XRD testing of the resulting product, as shown in Figure 4, zinc oxide in the map is a single crystalline type, so identified by the crystal index, the D value marked on the right side of the map is calculated by the Xiele formula to obtain the average particle size of zinc oxide powder. The results showed that the calcination time significantly affected the particle size of zinc oxide, but it had no significant effect on its crystalline type, and it was all six-way zinc ore structure. Increased calcination time from 60min to 150min, and its particle size gradually increased from 38.1nm to 39.6nm. The results of SEM show that zinc oxide is a typical speral structure and is evenly dispersed, as shown in Figure 3 (c) (d). In order to obtain zinc oxide with a smaller particle size, the calcination time needs to be set to 60min.3 Conclusion
The average particle size with good dispersion is 40nm zinc oxide powder by solid phase method and by manual grinding. The suitable process condition for small particle size sper sper oxide is 60min calcination time and 300C calcination temperature.
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