Study Of Microwave Effect On The Dynamics Of Reactive Crystallization Process

Microwave can be applied to control the crystallization process,but microwave effect on the crystallization process is not clear.In this study,the mechanism of the microwave effect on the crystallization process is analyzed.The mechanism of the microwave effect on primary nucleation is analyzed.The main effect of microwave on primary nucleation is to increase the diffusion coefficient(D_AB).The surface tension(?_CL)changes only slightly or remains constant in the microwave field.And when nucleation is predominantly heterogeneous,the effect of microwave on contact angle???,geometric factor?f?is not significant.This suggests that diffusion coefficient acceleration is the main reason for the reduction of the induction time.It is also found that(D_AB-D₀)has an exponential relationship with the energy input value of microwave.At the same energy input level,compared to homogeneous nucleation,the effect of microwave on diffusion coefficient was reduced by microscopic particles in the solution,when nucleation is predominantly heterogeneous.The microwave effect on induction time during primary nucleation was interpreted by a cluster coagulation model.In addition,the microwave effects on nucleation order?n?and nucleation coefficient?k_N?are also investigated,and the corresponding values of homogeneous nucleation are compared with the values of heterogeneous nucleation in the microwave field.when nucleation is prominently homogeneous,the dominant cluster size remains constant with different microwave energy inputs.And when nucleation is prominently heterogeneous,although the dominant cluster size increases with supersaturation increasing,at the same supersaturation level,the dominant cluster size remains constant in the microwave field.Combined with the experiment data of particle size distribution of microwave effect on the growth process during basic magnesium carbonate reactive crystallization,the high order model method of classes and high order back differential algorithm were introduced to solve the equation set.The unknown the kinetics parameters of crystallization were calculated based on the previous experimental data.It is found that the constant of nucleation rate?k_n?,the constant of growth rate?k_g?and the constant of agglomeration rate(C_ag)increased with the microwave energy?E?input,but the exponent of growth rate?q?decreased with the microwave energy?E?input,and the effect of microwave on the exponent of nucleation rate?n?and the constant of breakage rate(k_br)is not significant.The results of model showed excellent agreement with the experimental data and provided better understanding of the microwave effect on the crystallization process during reactive crystallization.The research results in this work were not found in the existing literatures.