The effect of microwave on the crystallization process of magnesium carbonate from aqueous solutions

Abstract

The effect of microwave on reactive crystallization is investigated with magnesium carbonate as the working substance. In the experiments, magnesium carbonate is precipitated by mixing aqueous magnesium sulfate and sodium carbonate solutions in a MSMPR crystallizer located in a microwave reactor. A population balance model along with crystallization kinetics is formulated to assess the influence of microwave energy input on nucleation, growth, agglomeration and breakage during crystallization process. A general high order moment method of classes (HMMC) framework is applied to solve the model numerically. The results show that crystallization kinetics parameters, including the nucleation rate constant (kn), the growth rate constant (kg), the exponent of growth rate (g) and the collision efficiency (Ψag) change significantly due to mass transfer enhancement in microwave field. Meanwhile, the exponent of nucleation (n) and the breakage rate constant (kbr) remain constant or only change slightly. It is further discovered that the crystal suspension attenuates the microwave effect during crystallization process.

Effect of cross‐linking degree on proton conductivity of a Schiff‐Base network impregnated with Brønsted acids

“…As shown in Figure S3, they exhibit a series of irregular and aggregated imperfect‐spherical nanoparticles, and SNW‐S possibly yields relatively larger sized particles than that of SNW‐M. In the presence of the microwave irradiation, 47 the crystal nucleation is greater than growth rate, comparison to solvothermal method, and the rapid polycondensation of the monomers is not conducive to the growth of particles. Differently, the slow reaction process in the solvothermal method makes the SNW more cross‐linked and denser packing.…”

Systematic Study on Heating Characteristics of a Rotating Coaxial Probe-Type Microwave Reactor

“…Localized overheating leads to high-temperature domains inside the reactor, which in turn leads to phase transitions and thermally induced crystal quality degradation. 26,27,59 It was reported that as Hs decreases, the proportion of regularly shaped particles gradually increases, which results in smaller particle sizes and narrower particle distributions due to the reduced degree of hot spots. Therefore, based on the correlation between the Hs value and the size of the synthesized particle morphology, it is reasonable and effective to use it as the main index to evaluate the performance of the designed reactor.…”