Understanding the role of different operating modes and ultrasonic reactor configurations for improved sonocrystallization of lactose

Abstract

The current work focuses on understanding the effect of different ultrasonic reactors on the recovery of lactose using crystallization. Three different scales of operations selected in the work include laboratory scale, medium scale and pilot scale based on the different reactor configurations. Ultrasonic bath (25 kHz) showed higher recovery of 90.3 ± 0.3 % for 20 min of sonication as compared to ultrasonic horn (20 kHz) with recovery of 88.8 ± 0.6 % with a standing time of 24 h in both the cases. Analysis of variance (ANOVA) demonstrated the significant dominance of all the factors studied on the response (recovery). The dual frequency ultrasound reactor (22 + 44 kHz) proved to be more efficient in delivering higher recovery values as compared to ultrasonic bath in the case of large scale systems with maximum recovery of 91.3 ± 0.9 %. The recovery of ethanol used as antisolvent was performed using distillation and the reusability of ethanol was studied. It was demonstrated that ethanol could be very well recycled, which is an important aspect at large scale operation. Overall, a systematic study helped in elucidating the role of ultrasonic parameters and reactor configuration in deciding an energy efficient and economical approach for maximum lactose recovery.