The multiple stages towards crystal formation of L-glutamic acid

Influence of Taylor Vortex Flow on the Crystallization ofl-Glutamic Acid as an Organic Model Compound

“…The result showed the presence of nanoscale particles with a diameter of 10–20 nm (see red arrow in Figure a); SAED revealed that these are in an amorphous state (see the inset picture in Figure a). Based on earlier contributions, it is reasonable to assume that these amorphous intermediates form from prenucleation clusters that already existed in the precritical stage. , Based on TEM analysis, it was reported that these prenucleation clusters contain about 25–68 molecules and feature sizes of 5.0–7.0 nm. , In the course of the formation process, these particles were found to grow larger (to 100–120 nm, see Figure b), probably due to the aggregation/coalescence processes (see yellow arrow in Figure a). In contrast to the expected spherical morphology of these precursors (see Figure b), also amorphous intermediates with distinct shapes were found, ranging from oval, and ellipsoid, to irregular shapes (see Figure c–f).…”

“…During crystallization, the solution temperature was controlled via the circulating coolant from the chiller (RCHCR20, CPT, Korea) to the outer jacket of the crystallizer; here, the solution temperature was detected by LabView (National Instruments). 37 The feed solution was pumped into the crystallizer, and crystallization was accomplished by gradually decreasing the solution temperature at a cooling rate of 0.5 °C/min. The reaction solution (liquid/suspension) was repeatedly sampled during the experiment, and the suspensions were separated by vacuum filtration.…”

“…The CT and ST crystallizers were operated at the same working volumes of 400 mL, rotation speeds, feed concentrations, and cooling rates. During crystallization, the solution temperature was controlled via the circulating coolant from the chiller (RCHCR20, CPT, Korea) to the outer jacket of the crystallizer; here, the solution temperature was detected by LabView (National Instruments) …”

“…Based on earlier contributions, it is reasonable to assume that these amorphous intermediates form from prenucleation clusters that already existed in the precritical stage. 37,45 Based on TEM analysis, it was reported that these prenucleation clusters contain about 25−68 molecules and feature sizes of 5.0−7.0 nm. 37,45 In the course of the formation process, these particles were found to grow larger (to 100−120 nm, see Figure 6b), probably due to the aggregation/ coalescence processes (see yellow arrow in Figure 6a).…”

“…37,45 Based on TEM analysis, it was reported that these prenucleation clusters contain about 25−68 molecules and feature sizes of 5.0−7.0 nm. 37,45 In the course of the formation process, these particles were found to grow larger (to 100−120 nm, see Figure 6b), probably due to the aggregation/ coalescence processes (see yellow arrow in Figure 6a). In contrast to the expected spherical morphology of these precursors (see Figure 6b), also amorphous intermediates with distinct shapes were found, ranging from oval, and ellipsoid, to irregular shapes (see Figure 6c−f).…”