Continuously scaled-up preparation of poly(l-lactic acid) microspheres using high gravity RPB

High-throughput preparation of the specific size (20–50 μm) microspheres with narrowly distributed is of significant interest to the medical aesthetics market. This study developed a novel method for preparing this kind of poly(l-lactic acid) (PLLA) microspheres using high-gravity rotating packed bed (RPB) reactor. Investigated the effects of operating parameters, initial liquid distribution and wire mesh packing wettability on microspheres size distribution. The RPB system was configured with a composite jet for the initial liquid distribution and a modified wire mesh packing featuring a lotus-leaf-like self-cleaning surface to intensify liquid dispersion. The prepared PLLA microspheres is of D 50  = 31.27 μm, with a distribution span of 0.78. Employing a dimensionless group analysis, correlations were established to predict the average particle size and uniformity of the PLLA microspheres. The predicted values showed good agreement with experimental data, typically within a ± 10% deviation. Based on the obtained results, a large scale test was carried out, achieving a production capacity of 2 kg/h. The PLLA microspheres prepared on a large scale have a D 50  = 41.29 μm, with a distribution span of 0.70. High-gravity RPB, with its superior liquid–liquid heterogeneous mixing capability, should be a promising candidate for the large-scale production of polymeric microspheres.