Solid State Preparation And Properties Of ZnO Nanocomposites

The synthesis of organic wastewater adsorbent and photodegradation catalyst with high capacity and activity is of great significance to solve the current environmental crisis.Eliminating harmful/toxic solvents and reagents,reducing reaction time,and developing new environmentally recyclable catalysts and adsorbents are among the most important principles of green chemistry.Solid phase synthesis of nanomaterials by mechanochemical synthesis is a novel method.Compared with traditional solution method,hydrothermal method,microwave hydrothermal method and harmonic chemical method,mechanical method has the advantages of short reaction time,no solvent or trace solvent,large amount of preparation and low energy consumption.It’s been used more and more in the last few decades.In this paper,ZnO,ZnO/g-C₃N₄ and Zn-MOFs nanomaterials were synthesized by mechanical chemical synthesis of solid phase reaction.The following research results are obtained:（1）Zn（NO₃）₂,ZnCl₂,Zn（CH₃COO）₂ and sodium hydroxide were ground in a mortar to cause solid-phase reaction to synthesize ZnO nanomaterials.The different raw material ratios,types of zinc salts and surfactants were studied.The effect on the morphology of ZnO nanocrystals.The type of zinc salt and the ratio of zinc salt to sodium hydroxide significantly affect the morphology and grain size of the product.The alkali content（i.e.,the content of NaOH）of the reaction system changes the morphology and The size has a significant effect,increasing the alkali content in the raw material will promote ZnO to become flaky grains,but the axial increase is more obvious,indicating that the strong alkaline environment is more conducive to the preparation of one-dimensional ZnO nanomaterials.Zn（NO₃）₂can play a role in changing the crystal morphology and size.（2）Using melamine as a raw material,self-made g-C₃N₄ is prepared by heat treatment.The solid-phase grinding technology is used to synthesize ZnO/g-C₃N₄ composite material,and sodium dodecylbenzenesulfonate is added to regulate the morphology of the product.Photodegradation activity of methylene blue under visible light.When not doped with sodium dodecylbenzenesulfonate,the ZnO/g-C₃N₄ composite prepared by solid-phase reaction showed good photocatalytic performance.In minutes,76%of methylene blue can be degraded.When doped with sodium dodecylbenzenesulfonate,it can promote g--C₃N₄ crystal form change,meanwhile it can be thinned and refined into nano-sheets.When the content of g-C₃N₄ When it is low,zinc oxide is supported by nanosheets on g-C₃N₄ nanosheets;when g-C₃N₄ content is high,nano-ZnO particles are supported on g-C₃N₄ nanosheets.These two photocatalysts have excellent photocatalytic performance.Under visible light irradiation,at100 minutes,the degradation degree of L-ZnO/g-C₃N₄ to methylene blue is 99%,and the degradation degree of H-ZnO/g-C₃N₄ to methylene blue is 96%.（3）The planetary ball mill is used as a mechanochemical reaction device,tungsten carbide is used as a grinding medium,commercially available cheap zinc oxide,isonicotinic acid,and isophthalic acid are used as reaction raw materials,and tens of microliters（1 to 3drops）of water,N,N-dimethylformamide and methanol were used as grinding auxiliary solvents,and zinc metal-organic framework materials（Zn-MOFs）were prepared by mechanochemical solid phase.Zn-MOFs were used as precursors and carbonized at high temperature and temperature.High porosity ZnO/C composites were prepared by high temperature carbonization of Zn-MOFs as precursors.The adsorption performance of ZnO/C composites on methylene blue pollutants in organic wastewater was studied.The results show that the synthesized material has a high adsorption capacity to methylene blue,and the adsorption capacity of Zn-MOF-1 composite material（40mg）to MB（40mg/l,40ml）reached97%within 100 minutes after heat treatment of Zn-MOF-1 at 800℃.The study of adsorption kinetics shows that the adsorption of the synthesized ZnO/C-1 composite material to methylene blue conforms to pseudo-second-order kinetics,which indicates that the adsorption of the adsorbent ZnO/C-1 to methylene blue is chemisorption.