Preparation Of Octahedral NiO And Its Photocatalytic Degradation Of Rhodamine B

In this thesis,we fabricated monodisperse octahedral NiO materials by solvent evaporation method and they were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy and thermogravimetric analysis.The effects of different preparation methods,calcination temperature and calcination time on the catalytic activity of photocatalysts were studied by UV photocatalytic degradation of rhodamine B solution.The characterized results showed that the carbon acts as template to adsorb the metal ions in precursor,and the product is NiO after calcinating at 600 ?.It showed high crystallinity and no other impurity phase.With the increase of calcination temperature,the crystallinity of the crystal is better.The conditions for the formation of the octahedral material were calcined at 600 ° C for 6 h.This morphology is mainly influenced by two aspcts:(1)the role of carbon spheres;(2)the role of hydrochloric acid.The formation of the morphology can be described as follows: First,at the time of preparation of the precursor,since the surface of the carbon spheres have hydrophilic groups,the metal ions are adsorbed on the carbon sphere.Then,during the calcination process,the as prepared carbon spheres stacked together,gradually growing from small particles.The growing process was terminated in(111)surfaces due to chloride ions,and thus the octahedron morphology can be formed.Photocatalytic degradation experiments showed that the prepared octahedral NiO has the best photocatalytic effect.Then the reaction kinetics of degradation of dyes with nickel oxide was studied by using Rhodamine B as model.The effects of the initial concentration of the RhB solution,the pH value of the RhB solution and the dosage of catalyst on the reaction kinetics parameters were investigated.The results showed that the photocatalytic degradation of rhodamine B by nano-nickel oxide is a first-order reaction,and the reaction law can be described by Langmuir-Hinshelwood kinetic equation.The initial concentration of dye solution has a certain effect on the degradation rate,that is,with the increase of rhodamine B concentration,the degradation rate slows down,and the first order kinetics constant k decreases with the initial concentration of dye solution.The pH value of the dye solution also affects the degradation rate,and the first order reaction kinetics constant k is larger when the pH is extreme higher or lower.With the increase of catalyst dosage,the degradation rate of rhodamine B was improved firstly.When the dosage was 50mg/L,with the increasing dosage of catalyst,the reaction rate decreased.Dye degradation is unfavorable.