Crystal‐size distribution (CSD) is one of the most important parameters in sugar production. The objective is to grow crystals of uniform sizes or narrow CSD. CSD appears to be determined by the growth‐rate history of the crystals and the relative supersaturation (SS) of the solution from which crystals growth takes place. Three methods for preparation of nucleation seeds were described and used for industrial crystallization of raw and white sugars; these are wet milling filtered sugar (ML), agitating saturated solution (AS) and powdered sugars (PD). Rosin–Rammler (RR) and mathematical models were adopted to investigate CSD and the uniformity of the produced crystals. Higher uniformity coefficients were reported for the AS seeded crystals than the other two seeding methods. Furthermore, higher crystal contents were obtained for the AS seeded white sugar batches in comparison.
Production of micronized ammonium perchlorate particles (AP) (< 25 μm) has a great importance in the composite solid propellant industry. In the present study, an attempt was made to consider thermo-kinetic preparation of AP particles by using simple McCabe model in a cooling crystallization system. For this reason, an experimental design based on temperature, pressure, time, and concentration was used. Temperature in the range of 323-343 K, pressure in the range of 3�10 5 -18�10 5 Pa, and concentration in the range of 0.4-0.5 g/mL were set for the experiments. The time parameter was variable regarding to the temperature and concentration of each experiment and it was measured to evaluate the rate of process. The crystal size as an experiment response was estimated using image analysis of produced samples by MIP software in micrometer scale. Finally, a growth rate equation was established considering the results obtained from temperature variations, pressure, concentration, and time. Decrease in temperature variations caused to increase in crystallization rate and crystal size. The pressure above 7.5�10 5 Pa resulted in producing crystals smaller than 40 μm. The lowest crystal size was observed in the concentration of 0.45-0.5 g/mL and the crystallization time below 8 s. In addition, the results obtained from presented equation and experiment were matched with McCabe model.
In this research, Ag‐Al2O3 nanostructures have been prepared via combustion synthesis and ammonium acetate and urea have been applied as fuels. The prepared Ag‐Al2O3 nanostructures were characterized by DTA, XRD, SEM, TEM, and BET spectroscopy. The effect of different ratios of silver to alumina and fuel percentage on morphology and particle size of prepared products were investigated. The results showed that using ammonium acetate fuel led to the production of Ag‐γ‐Al2O3 nanocompounds, while using urea produced Ag‐α‐Al2O3. Also, the photocatalytic activity of Ag‐Al2O3 nanostructures for Congo red degradation was evaluated by UV‐Vis diffuse reflectance spectroscopy. The photocatalytic activity of Ag‐Al2O3 was examined under UV‐Vis irradiation and showed significant photocatalytic efficiency.
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