Study On Preparation Of Palladium Single Particles By Ginkgo Biloba Extract

Metal nanoparticles are important research fields in modern science,and its traditional preparation methods including chemical method,physical method,biological synthesis method.The emerging biological synthesis of metal nanoparticles in recent years is one of the highlights of the cross nanotechnology and green technology.Therefore,more and more attention has been paid to it.Palladium metal is a commonly used catalyst,has been widely used in organic synthesis,catalytic degradation,methane combustion and so on.The size and morphology of the palladium has a significant influence on the catalyst activity and selectivity,so prepared with different size and shape of the palladium is key technology research.It is also important for quantitative study on synthesis of metal nanoparticles by biological method.The aim of this paper is to prepare palladium particles by reducing PdCl₂ solution by the extraction of Ginkgo biloba,and to explore the quantitative analysis method of plant reduction method,and to study the effect of different experimental conditions and different substances on the morphology of palladium particles.In the 2,3 chapter,the qualitative and quantitative research on the preparation of palladium nanoparticles by plant reduction method is carried out.The 4 chapter studies the effects of different experimental conditions on the morphology of palladium particles: the concentration of reactants?concentration of Ginkgo biloba extract,PdCl₂ solution concentration?and p H value were investigated respectively.The 5 chapter studies the effects of adding different substances on the morphology of palladium particles.The factors of adding reductant / oxidant,protectant / stabilizer,capping agent / guide agent are investigated respectively.Through the above analysis,the following conclusions can be drawn:?1?The extraction solution of Ginkgo biloba leaves can be used to reduce PdCl₂ solution to prepare palladium nanoparticles,which can be quantitatively studied by plasma emission spectrometry.?2?By changing the different experimental conditions can be controlled palladium particle size and morphology.By adjusting the concentration of Ginkgo biloba extract,can be prepared linear,lumps,pit head,pea,rod and spherical palladium particles.With the increase of extract concentration,the morphology of the product evolved from linear ? rod-like entities ? curved-surface entities ?globular.By adjusting the concentration of PdCl₂ solution added to the reaction solution,linear,rod-shaped,irregular spherical palladium particles can be prepared.With the increase of the concentration of PdCl₂,the evolution of palladium particles morphology can be summarized as:thick linear loose body ? thinner linear aggregates ? rod-shaped ? irregular spherical.When the concentration of PdCl₂ solution is low,it is good for the preparation of linear palladium particles,while PdCl₂ solution concentration is higher,which is conducive to the preparation of rod-shaped palladium particles.By changing the p H of the reaction solution,the size and morphology of Pd particles can be controlled.Adjusting the p H of the reaction solution can prepare spherical particles,linear or triangular irregular geometric palladium particles.With the increase of the p H value of the reaction solution,the morphologies of the product morphology are roughly: linear ? flocculent and geometric shape ? globular and geometric shape ? globular.When the pH value is acidic,it is good for the preparation of linear palladium particles.When the p H value is alkaline,it is good for preparing spherical palladium particles.When the p H value is neutral,it is convenient to prepare palladium particles with irregular geometric shapes and small size.?3?The size and morphology of palladium particles can be regulated by adding different substancesThe size and morphology of palladium particles can be controlled by adding different reducing agents / oxidants.Adding different reducing agent / oxidant,can be prepared spherical /nearly spherical,linear,rod-shaped palladium particles.Reducing ability helps to prepare linear palladium particles,and weak reducing ability helps to prepare rod-shaped palladium particles.Addition of different protectants / stabilizers weakly controls the size and morphology of palladium particles.They are not conducive to the product of anisotropic growth,the products are mostly spherical,nearly spherical morphology.The size and morphology of the palladium particles can be controlled by adding different capping agents / cootants.Adding inorganic anions Cl-,Br-,I-can be prepared spherical,nearly spherical,linear,irregular palladium particles.The ability to form anisotropy Cl-> Br-> I-.After adding different inorganic cations Mn²⁺,Fe³⁺,Co²⁺,Ni²⁺,Cu²⁺,Zn²⁺,many different morphologies of palladium particles appeared.