Preparation Of Ago Materials By Membrane Contact Reactor And Study On Crystallization Kinetics Of Its Product

AgO materials have strong bactericidal,oxidative and photocatalytic abilities,and have potential application prospects in bactericidal,high-performance batteries and drinking water purification.At present,the reactor used to prepare AgO has the characteristics of unstable reaction interface and random contact of reactants,which lead to unclear kinetics of the preparation process,difficult to scale up production and unable to effectively control particle size.Therefore,the ceramic membrane contact reactor with controllable reaction interface and reaction on the surface of the membrane was used as the reactor.AgO materials were prepared by liquid-liquid oxidation system.The effects of concentration of AgNO3,K2S2O8 and NaOH,temperature of the reaction solution,pore size of the membrane,flow rate of AgN03 solution and pressure of oxidation liquid on AgO content,chemical conversion and size were studied,and the crystallization kinetics of AgO was simulated to provide a basis for the scale-up production and size control of AgO.The results showed that the concentration of AgNO3,K2S2O8 and NaOH,the temperature of reaction solution,the pore size membrane,the flow rate of AgN03 solution and the pressure of oxidation phase all had effects on AgO content and chemical conversion.When the reaction solution was fed into the shell of the reactor by gravity,it was necessary to place the oxidation solution at a height of two meters.The reaction time was long,which was not conducive to industrial production.There was no requirement for the position of the oxidation solution when the reaction solution was transported by a constant pressure device,and it was convenient to control the flow rate of the oxidation solution and shorten the reaction time.'The influence of'reaction parameters on the formation and conversion of AgO varies with the way of liquid-liquid entering the shell of the membrane contact reactor.The highest content of AgO and the highest chemical conversion rate were 78.2%and 44.5%under pressure and alkali,respectively.The optimum preparation parameters were as follows:temperature was70?,the concentration of AgNO3 was 0.118 mol/L,the concentration of K2S2O8 was 0.392 mol/L,the concentration of NaOH was 1.059 mol/L,the pore size of membrane was 50 nm,the flow rate of AgNO3 solution was 5 mL/min,and the pressure was 0.01 MPa.The addition of NaOH can reduce the dissolution of AgO by H+ in the reaction process and significantly improve the chemical conversion.The pore size of the membrane,the flow rate of AgNO3 solution,and the pressure of oxidation phase all affected the particle size.The growth rate of AgO crystals increased with the increase of membrane pore size and oxidation phase pressure,but the nucleation rate decreased,resulting in the increase of AgO particle size with the increase of pore size of the membrane and the pressure of oxidation phase.With the increase of flow rate of AgNO3,the growth rate and nucleation rate of AgO crystals increased.The crystallization kinetic model with the pore size of the membrane as a variable was B =5.79×10-18G-3.87.With the flow rate of AgNO3 as the variable,when the flow rate is less than 5 mL/min,the crystallization kinetics model was B0=4.57×1016G0.34.When the flow rate is greater than 5 mL/min,the kinetic model of crystallization was B0=1.01x1033G2.42 The crystallization kinetics model with the pressure of oxidation phase as variable was B0=1.2×10--G-2.82.