Purification of 2,4-dinitrochlorobenzene using layer melt crystallization: Model and experiment

In this study, layer melt crystallization was introduced to separate 2,4-dinitrochlorobenzene (2,4-DNCB) from the mixture of 2,4-DNCB and 2,6-DNCB. The multi-stages melt crystallization was used to achieve the ultrapure target product preparation, in which the final purity of 2,4-DNCB reached 99.94%. In the melt crystallization, several indicators including the fractal porous medium theory and separation performance modeling were introduced to evaluate the process behavior. The fractal porous medium theory including porosity and tortuosity were used to describe the inner crystal packing structure, quantitively. The separation performance parameters including distribution coefficient Kc, and sweating yieldYS were investigated to describe the separation efficiency. Furthermore, the sweating number was used to describe the implicit relationship between separation results and sweating intensity. The sweating behavior was also modeled with two approaches to correlate the sweating time with separation performance. Final, a sweating model was established to estimate the purity Cp(t) and yield Y(t) as a function of sweating time t and temperature T. Overall, layer melt crystallization is an effective approach to obtain ultrapure target products. The proposed parameters and models can describe and visualize the crystallization behavior successfully.

Automated summary

In this study, layer melt crystallization was used to separate 2,4-dinitrochlorobenzene (2,4-DNCB) from a mixture and achieve a purity of 99.94%. Through the introduction of fractal porous medium theory and separation performance modeling, the process behavior was successfully evaluated and visualized. This approach proved to be effective in obtaining ultrapure target products.