Research On The Green Continuous Preparation Process Of Nano-silver Biological Method And Its Numerical Simulation Method

With the increasing concern on environmental problems,researchers have paid more and more attention to the green preparation of industrial materials by using environmentally friendly raw materials.Silver nanoparticles(Ag NPs)have broad application prospects in catalysis,sensors and antibacterial materials,and the existing synthesis process of Ag NPs is basically carried out in batch reactor.How to achieve rapid and continuous preparation of Ag NPs has attracted extensive attention of scholars.Among them,the continuous preparation of silver nanoparticles by using microchannel reactor,especially microfluidic chip technology,is a popular continuous preparation technology today.However,existing studies only focus on the effect of experimental conditions on the particle size distribution of the final Ag NPs.The investigation of influence factors on Ag NPs in microfluidic chip using numerical simulation has not been reported.In addition,the continuous preparation technology of Ag NPs assisted by hydrodynamic cavitation reactor has not been reported.In this study,the continuous preparation of nano-silver was realized by the combination of environment-friendly plant biomass reduction technology and microfluidic chip reactor and hydrodynamic cavitation reactor.The effects of experimental conditions and functions on the formation and particle size distribution of Ag NPs were investigated.The main components are as follows:Firstly,Ag nanoparticles(Ag NPs)were plant-mediated synthesized in a microfluidic chip at room temperature.The formation process and particle size distribution(PSD)were numerically simulated by a multiphase flow model incorporating reactive kinetics and population balance equation(PBE).The influences of flow rate on particle size distribution were demonstrated in detail by both experimental research and simulative analysis.It was found that there was an identified flow rate of the microfluidic chip distinguishing the influences into two stages.At the first stage,mixing efficiency was the restrictive factor while residence time was the restrictive factor at the second stage.It has been concluded that the identified flow rate is the balance between mixing efficiency and residence time at which the average particle size can achieve the maximum value.Secondly,Ag NPs are continuously biosynthesized with CP leaf extract(0.3 g/L)at room temperature(30 °C)in the hydrodynamic cavitation device.The products are characterized by UV-Vis absorption spectra,XRD,TEM and HRTEM confirming Ag NPs with uniform distribution are successfully synthesized.A CFD and PBE coupled with reactive kinetics model is built to simulate the Ag NPs formation process numerically and calculate as well as predict the corresponding particle size distribution.The coupled model is validated accurately and effectively with experiment in simulating of Ag NPs formation and predicting the particle size distribution(PSD)in the hydrodynamic cavitation device.