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Continuous‐flow separation and recovery of silver nanoparticles (AgNPs) using an annular centrifugal extractor (ACE) is demonstrated. Separation was achieved at the liquid‐liquid interface based on the balance between centrifugal force and the solubility of the capping agent. A mathematical model is presented to understand the mechanism in greater detail. The separation of poly(vinylpyrrolidone) (PVP)‐coated AgNPs in an ACE using a strong immiscible solvent was performed. The material accumulated at the interface was separated periodically without discontinuing the operation. The method is also suitable for separation of large particles or 1D/2D nanostructures even employing a single annular centrifugal extractor. Stable AgNPs were selected for a detailed antimicrobial activity study. [ABSTRACT FROM AUTHOR]

The effect of interfacial mass transfer on the extent of dispersion in liquid-liquid segmented flow in straight capillaries is studied. In the absence of interfacial mass transfer, dispersion coefficient was seen to go through a minimum with increasing flow rates. In the presence of mass transfer, physicochemical properties of both the phases and slug lengths were seen to vary along the capillary length. The extent of dispersion was always higher in the presence of interfacial mass transfer. The predictions using axial dispersion model deviated noticeably for larger capillaries as the model does not account for varying buoyancy, dynamic contacting, and Marangoni convection. Simulations of a first-order interfacial reaction considering varying slug lengths showed a significant change in optimum operating parameters than the conventional approach. A special case of 'drop-on-demand' type of controlled two-phase flow in capillaries was also studied. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4294-4308, 2015 [ABSTRACT FROM AUTHOR]

This work aims to explore the application of metal monoliths as a scale-up option for efficient liquid-liquid extraction. The pressure drop, mass transfer and residence time distribution are measured for low Ca (∼10−5) with monoliths having three different cell densities. The cross-over section between two monoliths was seen to enhance mixing in the column. However, the RTD of two-phase liquid-liquid up-flow was inferior to the single phase RTD. For higher cell density substrates, the cross-over zones seem to cause trapping of slugs due to non-superimposing channel ends. Relatively high shear rates through the film of continuous phase helped enhance the mass transfer rates, thereby helping to achieve the desired extraction in a short column. The entrance sections and cross-over zones between the monoliths adversely affected the extraction for higher cell density monoliths. The analysis of data supports use of low cell density monolith for better performance and scale up. [ABSTRACT FROM AUTHOR]