Hydrodynamics of aqueous two-phase systems (ATPS) in millichannels

Gande, Vamsi Vikram; K, Hima Nandini; Korukonda, Jagadeesh; Pushpavanam, S.

doi:10.1016/j.ces.2022.118296

Cited by 8 publications

(5 citation statements)

References 23 publications

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“…The particle size was observed to be almost the same for the syntheses in the continuous phase as well as the dispersed phase of slug flow. This is attributed to the low film thickness present around the dispersed phase as the flow rates used are low . The mixing in the two phases, the continuous and the dispersed phases, were hence identical, and similar size distribution of the particles was obtained.…”

Section: Resultsmentioning

confidence: 79%

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Green Approach for the Simultaneous Synthesis and Separation of Gold Nanoparticles

Hima Nandini,

Sinu,

Pushpavanam

2023

Langmuir

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Gold nanoparticles (AuNPs) have diagnostic and therapeutic applications as they are biocompatible and can be surface-functionalized. The use of organic solvents in the synthesis of AuNPs hampers their applications in the medicinal field. The large-scale production of nanoparticles requires their simultaneous synthesis and separation. Self-assembly of nanoparticles at the fluid–fluid interface facilitates their separation from the bulk and eliminates a downstream processing step. In this work, we exploit this in an aqueous two-phase system (ATPS) to synthesize and separate stable AuNPs. The ATPS was based on polyethylene glycol (PEG) and trisodium citrate dihydrate (citrate) as both these compounds can reduce Au ions. After the synthesis of nanoparticles, using one of the solutes, a complementary solution containing the other solute is added to form a two-phase system to facilitate self-assembly at the interface. The nanoparticles synthesized in different phases are characterized using UV–visible spectroscopy, scanning electron microscopy, and transmission electron microscopy. The AuNPs synthesized using the citrate solution are found to be unstable. Particles synthesized using the ATPS with PEG-600 are trapped at the interface while those using PEG-6000 remain in the bulk. Continuous synthesis and separation of nanoparticles in slug flow in a millichannel are demonstrated as a first step for large-scale controlled synthesis.

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Section: Resultsmentioning

confidence: 79%

“…This is attributed to the low film thickness present around the dispersed phase as the flow rates used are low. 49 The mixing in the two phases, the continuous and the dispersed phases, were hence identical, and similar size distribution of the particles was obtained.…”

mentioning

confidence: 55%

Green Approach for the Simultaneous Synthesis and Separation of Gold Nanoparticles

Hima Nandini,

Sinu,

Pushpavanam

2023

Langmuir

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“…The dominance of interfacial force over the inertial force is also confirmed by a low Weber number ( W e d = ρ d d U d 2 γ false) of 0.0004 ( We d ) which is defined by the ratio of inertial force to the interfacial force. The significance of Ca of continuous phase, Re and We of dispersed phase for the evolution of segmented flow was inferred from hydrodynamic studies . From these dimensionless numbers, we deduce that for our system and operating conditions, the forces are in the order of interfacial > viscous > inertial.…”

Section: Results and Discussionmentioning

confidence: 80%

“…The relationship between these forces is determined by the dimensionless capillary number ( Ca ) and the Reynolds number ( Re ). When both Ca and Re ≪ 10° interfacial forces dominate . We achieved this by increasing the radius of the microchannel by an order of magnitude.…”

Section: Introductionmentioning

confidence: 97%

Continuous Synthesis and Separation of Silver Nanoparticles Using an Aqueous Two-Phase System

Gande,

Savitha,

Pushpavanam

2023

Ind. Eng. Chem. Res.

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Continuous synthesis of metal nanoparticles enables good control on quality and supports process automation. In this work, we have used a biocompatible aqueous two-phase system (ATPS) for the continuous synthesis of nanoparticles. We propose the use of a milli-channel to lower the capillary number. This ensures the dominance of interfacial forces and the system exhibits segmented flow in ATPS. The chaotic advection-based mixing within each slug is exploited for nanoparticle synthesis. Herein, we report for the first time the continuous synthesis and separation of silver nanoparticles using ATPS formed by polyethylene glycol 6000 and tri-sodium citrate. The phase separation in ATPS was explored for nanoparticle trapping at the interface. We investigated six different operating procedures based on the occurrence of mass transfer (ATPS formation) after, during, and before the reaction (synthesis) in both batch and continuous modes of synthesis. We believe the dominance of Van der Waals force over convective force is responsible for nanoparticle trapping at the interface. The physico-chemical properties of the nanoparticle obtained from different synthesis modes were characterized using localized surface plasma resonance and electron microscopy. The continuous mode of operation resulted in the shape-controlled synthesis of a nanoparticle compared to the batch process. The use of two-phase flow in the continuous mode eliminated the additional downstream step for particle separation. This has the potential for high-throughput nanoparticle production at the commercial scale.

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“…Then, two types of solutions are stirred together and fully mixed for 12 h. Finally, they are transferred in a separatory funnel where the heavy phase is aqueous solution enriched with trisodium citrate and the light phase is aqueous solution enriched with polyethylene glycol, which are represented by TSC and PEG, respectively. The aqueous two-phase solutions used in the study are generally considered as Newtonian fluid. − The oil phase is the ionic liquid [BMIM]–[PF 6 ] (AR, Henan Lihua Pharmaceutical Co., Ltd.), which is represented by PF 6 .…”

Section: Methodsmentioning

confidence: 99%

Spontaneous Transfer of Droplets across a Microfluidic Liquid–Liquid Interface

Yi,

Fu,

et al. 2024

Langmuir

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The droplet transfer across an interface in a microchannel is extensively utilized in diverse fields; however, it is challenging to drive droplets to penetrate the interface at such a small scale. In this study, a novel flow pattern of droplet transfer is observed and the mechanism is investigated; accordingly, an accurate prediction equation for determining the critical condition of droplet transfer is proposed. Meanwhile, the liquid film entrainment is also observed, which leads to the formation of an oil-in-water-in-water system. This study serves as a valuable reference for further studies on the mechanism of droplet transfer and provides practical guidance for its industrial application.

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Hydrodynamics of aqueous two-phase systems (ATPS) in millichannels

Cited by 8 publications

References 23 publications

Green Approach for the Simultaneous Synthesis and Separation of Gold Nanoparticles

Green Approach for the Simultaneous Synthesis and Separation of Gold Nanoparticles

Continuous Synthesis and Separation of Silver Nanoparticles Using an Aqueous Two-Phase System

Spontaneous Transfer of Droplets across a Microfluidic Liquid–Liquid Interface

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