Evaluation of different cavitational reactors for size reduction of DADPS

The present study deals with the size reduction based on the recrystallization (antisolvent approach using water) of 3,3′-Diamino Diphenyl Sulfone (DADPS) using different types of cavitational reactors as an alternative to the conventional process of mechanical size reduction, which is an energy intensive approach. Ultrasound was applied for fixed time specific to the reactors namely ultrasonic probes at different power dissipation levels and also ultrasonic bath. A High Speed Homogenizer was also used at varying speeds of rotation to establishing the efficacy for size reduction. The processed sample was analysed for particle size and morphology using particle size analyser and optical microscopy respectively. The final yield of recrystallization was also determined. The power density in W/L and power intensity in W/m² calculated for each equipment has been used to establish efficacy for size reduction since all devices had dissimilar configurations. Based on the studies of varying power intensity of the different US equipment, it was established that larger the power intensity and power density, smaller was the resultant final particle size after treatment for same time. Among the various ultrasonic devices used, Sonics VCX750 probe yielded the best size reduction of 85.47% when operated at 40% amplitude for 60 min for a volume of 200 ml. A High Speed Homogenizer used at 7000 rpm gave 92.35% of size reduction in 15 min operation and also demonstrated the best energy efficiency. The work has elucidated the comparison of different cavitational devices for size reduction for the first time and presented the best reactors and conditions for the desired size reduction.