Modularized microfluidic synthesis of functional chitosan adsorbents for deep treatment of azo dye effluent
Multichannel integrated microfluidic technology retains the precise control characteristics of microfluidics. This technology is expected to replace traditional droplet preparation techniques for the batch production of adsorption materials with high performance and high monodispersity. In this study, porous chitosan microspheres (PCSM) were successfully synthesized using a self-developed modularized microfluidic system. As-prepared PCSMs were employed in adsorption separation of methyl orange (MO). The results proved that the average droplet size of PCSMs was 892 μm with the lowest coefficient of variation (CV), only 2.75%, while, the droplet flux was up to 210 mL·h−1. Batch static adsorption experiments showed that the saturated adsorption capacity of the adsorbent reached 215.26 ± 2.22 mg·g−1. Besides, the adsorption kinetics and equilibrium adsorption isotherm fitted pseudo-second-order kinetic model and Langmuir isotherm model well, respectively, indicating that the adsorption process is dominated by chemical reaction. Moreover, continuous adsorption experiment showed that under the conditions of initial solution concentration of 40 mg·L−1, bed diameter of 15 mm and filling height of 9.3 mm, the breakthrough time was 140 min, and the maximum adsorption capacity was up to 233.3 ± 4.30 mg·g−1. In addition, PCSMs exhibited stable regeneration performance and efficient selective adsorption for MO dyes in recycling (73.4% reabsorption productivity after 5 cycles). This study can provide theoretical support for the microfluidic batch synthesis and industrial application evaluation of high-performance adsorbents.
