02317nas a2200217 4500008004100000022001400041245011300055210006900168260006900237300001200306490000800318520148300326653002101809653002901830653001701859653002401876100002301900700003001923700002301953856012301976 2012 eng d a1385-894700aSegmented flow synthesis of Ag nanoparticles in spiral microreactor: role of continuous and disperzsed phase0 aSegmented flow synthesis of Ag nanoparticles in spiral microreac aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcJUN a357-3680 v1923 a

This work focuses on understanding the effect of segmented flow on the nanoparticle size distribution in a unidirectionally expanding spiral microreactor, where secondary flows are prevalent in the absence of segmentation. Stearic acid sophorolipid reduced/capped Ag NPs were synthesized in the aqueous phase and air or kerosene was used as inert phases for creating the gas-liquid and liquid-liquid segmented flow, respectively. While, in one case the reactant phase is in the form of dispersed phase slugs, in the other case it is in the form of continuous phase, each exhibiting a different behavior. The slug sizes and the slip velocity, both of which govern the nature of internal mixing in the reactant phase slug controlled the nanoparticle size distribution. This observation was consistent for both, gas-liquid and liquid-liquid segmented flows. The micromixer having smaller orifice diameter yielded smaller slugs and also a narrow particle size distribution. In general, the particle sizes were much smaller for gas-liquid flow rather than for liquid-liquid flow. Because of the unidirectionally expanding spiral geometry of the channel, at any given condition, unsteady behavior of slugs due to continuously varying radius of curvature results in variation in the slip velocity along the length of microchannel. This effect was seen to further narrow the particle size distribution than alone by the segmented flow. (C) 2012 Elsevier B.V. All rights reserved.

10aAg nanoparticles10aSegmented flow synthesis10aSophorolipid10aSpiral microreactor1 aKumar, D., V. Ravi1 aPrasad, Bhagavatula L. V.1 aKulkarni, Amol, A. uhttps://library.ncl.res.in/content/segmented-flow-synthesis-ag-nanoparticles-spiral-microreactor-role-continuous-and-001749nas a2200169 4500008004100000245010200041210006900143260000800212300001400220490000700234520111500241100003001356700001601386700002301402700002201425856013201447 2012 eng d00aSize-controlled flow synthesis of gold nanoparticles using a segmented flow microfluidic platform0 aSizecontrolled flow synthesis of gold nanoparticles using a segm cMAY a7007-70130 v283 a

Segmented flow is often used in the synthesis of nanomaterials to achieve narrow particle size distribution. The narrowness of the distribution is commonly attributed to the reduced dispersion associated with segmented flows. On the basis of the analysis of flow fields and the resulting particle size distribution, we demonstrate that it is the slip velocity between the two fluids and internal mixing in the continuous-phase slugs that govern the nature of the particle size distribution. The reduction in the axial dispersion has less impact on particle growth and hence on the particle size distribution. Synthesis of gold nanoparticles from HAuCl4 with rapid reduction by NaBH4 serves as a model system. Rapid reduction yields gold nuclei, which grow by agglomeration, and it is controlled by the interaction of the nuclei with local flow. Thus, the difference in the physical properties of the two phases and the inlet flow rates ultimately control the particle growth. Hence, a careful choice of continuous and dispersed phases is necessary to control the nanoparticle size and size distribution.

1 aCabeza, Victor, Sebastian1 aKuhn, Simon1 aKulkarni, Amol, A.1 aJensen, Klavs, F. uhttps://library.ncl.res.in/content/size-controlled-flow-synthesis-gold-nanoparticles-using-segmented-flow-microfluidic-platform02045nas a2200253 4500008004100000022001400041245008100055210006900136260007300205300001200278490000800290520113200298653002101430653002201451653001801473653002701491653003701518653002601555653002301581100002301604700002301627700003001650856011101680 2013 eng d a0927-775700aSynthesis of triangular gold nanoplates: role of bromide ion and temperature0 aSynthesis of triangular gold nanoplates role of bromide ion and  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR a181-1900 v4223 a

Synthesis of noble metal triangular nanoplates is a kinetically controlled process in which temperature and packing defects play a major role. Nucleation and growth process of kinetically controlled reaction can be greatly influenced by temperature affecting the yield and edge length of the triangles. Through a conventional batch mode process, here we study the effect of temperature on nucleation and growth of gold triangular nanoplates and obtain some insight of the temperature effects on the final yield and edge length of triangles. The role of Br- ions in the synthesis of triangular nanoplates is studied by varying the amount of CAB and by replacing the CTAB with HBr. The results show that, while CTAB controls the edge length and yield of triangles, its use is not mandatory to attain plate like morphology. Finally we show that, while the initial temperature of the reaction mixture governs the nucleation rate and the rate of temperature rise governs the growth rate of particles, they along with the concentration of Br- ions control the edge length and yield. (C) 2013 Elsevier B.V. All rights reserved.

10aAu nanotriangles10aHalide ion effect10aheat transfer10aKinetically controlled10aNature of gold precursor complex10aNucleation and growth10aOptical properties1 aKumar, D., V. Ravi1 aKulkarni, Amol, A.1 aPrasad, Bhagavatula L. V. uhttps://library.ncl.res.in/content/synthesis-triangular-gold-nanoplates-role-bromide-ion-and-temperature-001944nas a2200157 4500008004100000245008700041210006900128260000800197300001200205490000600217520138900223100001901612700002301631700002201654856011001676 2016 eng d00aSelectivity engineering of the diazotization reaction in a continuous flow reactor0 aSelectivity engineering of the diazotization reaction in a conti cAPR a387-3960 v13 a

In situ generated diazonium salts are useful intermediates for the synthesis of fine chemicals and active pharmaceutical ingredients. This paper presents a methodology for selectivity engineering of the diazotization reaction in a continuous reactor. The yield of diazotization was found to depend on mixing, dispersion, reaction kinetics, operating temperature and residence time. Initially, experimental data and an isothermal axial dispersion model were used for estimating mixing time. A correlation for estimating mixing time for different flow reactors is proposed. The model predictions were compared with the experimental data. The validated axial dispersion model and Central Composite Design (CCD) were used to optimize diazotization in a straight tube reactor (1.78 mL). The model was then used for scaling-up of aniline diazotization from a straight tube reactor to a proprietary AmAR3 reactor (scale-up ratio of ∼20). The initial concentration, inlet temperature, average heat capacity of the reaction mixture, mixing, residence time (distribution) and available heat transfer area per unit volume of the reactor were found to be the key parameters for scaling-up of the diazotization reaction. The presented approach and results will be useful to practicing chemists and engineers for enhancing the selectivity of diazotization reactions in continuous reactors.

1 aShukla, C., A.1 aKulkarni, Amol, A.1 aRanade, Vivek, V. uhttps://library.ncl.res.in/content/selectivity-engineering-diazotization-reaction-continuous-flow-reactor01454nas a2200169 4500008004100000022001400041245010100055210006900156260000900225300001200234490000600246520083400252100002401086700002601110700002301136856012501159 2020 eng d a2058-988300aSelectivity engineering of Meerwein arylation in a continuous flow reactor: a modelling approach0 aSelectivity engineering of Meerwein arylation in a continuous fl cAPR  a736-7460 v53 a

This paper presents a methodology for selectivity engineering of Meerwein arylation in a flow reactor. The reaction was optimized in batch mode and reaction kinetics were obtained over a range of temperatures and catalyst concentrations. A lumped kinetic model was formulated and the parameters were estimated using nonlinear regression. Furthermore, telescopic flow synthesis for Meerwein arylation via in situ diazonium salt generation and coupling was demonstrated. A non-isothermal model was developed and experimentally validated. The effect of initial concentration and inlet temperature on the yield of the desired product was estimated for various catalyst concentrations. The results from the simulations in terms of nondimensional numbers were used to find suitable operating conditions for Meerwein arylation.

1 aShukla, Chinmay, A.1 aAtapalkar, Ranjit, S.1 aKulkarni, Amol, A. uhttps://library.ncl.res.in/content/selectivity-engineering-meerwein-arylation-continuous-flow-reactor-modelling-approach01355nas a2200181 4500008004100000022001400041245008600055210006900141260000800210300001400218490000700232520072200239100002600961700002500987700002101012700002301033856011701056 2021 eng d a1463-926200aScalable, sustainable and catalyst-free continuous flow ozonolysis of fatty acids0 aScalable sustainable and catalystfree continuous flow ozonolysis cMAR a2391-23960 v233 a

A simple and efficient catalyst-free protocol for continuous flow synthesis of azelaic acid is developed from the renewable feedstock oleic acid. An ozone and oxygen mixture was used as the reagent for oxidative cleavage of double bond without using any metal catalyst or terminal oxidant. The target product was scaled up to more than 100 g with 86% yield in a white powder form. Complete recycling and reuse of the solvent were established making it a green method. The approach is significantly energy efficient and also has a very small chemical footprint. The methodology has been successfully tested with four fatty acids making it a versatile platform that gives value addition from renewable resources.

1 aAtapalkar, Ranjit, S.1 aAthawale, Paresh, R.1 aReddy, Srinivasa1 aKulkarni, Amol, A. uhttps://library.ncl.res.in/content/scalable-sustainable-and-catalyst-free-continuous-flow-ozonolysis-fatty-acids01397nas a2200169 4500008004100000022001400041245007500055210006900130260000800199300001000207490000700217520083900224100002301063700002301086700001701109856010101126 2021 eng d a1341-721500aSolvent extraction of copper enhanced by mixing cavities in micromixer0 aSolvent extraction of copper enhanced by mixing cavities in micr cJUL a37-470 v283 aA Y micromixer with a macroscopic mixing cavity at the inlet junction was developed. The effects of the mixing cavity on the improvement of extraction of copper by LIX 841 were investigated. The investigated parameters and their ranges were: overall flow rate: 10 - 200 mL/min; microchannel size: 0.5 - 1 mm and mixing cavity diameter: 5 - 20 mm. Extraction efficiency, volumetric mass transfer coefficient, kinetics and pressure drop were investigated. The extraction efficiency and the volumetric mass transfer coefficient in the cavity micromixer were significantly higher than the Y micromixer. The volumetric mass transfer coefficient ranged between 1 - 93 s(-1), and the pressure drop between 50 - 500 kPa. The residence time required in the micromixers was two orders of magnitude lesser than that of an agitated batch reactor.1 aSheik, Abdul, Rauf1 aKulkarni, Amol, A.1 aSanjay, Kali uhttps://library.ncl.res.in/content/solvent-extraction-copper-enhanced-mixing-cavities-micromixer01895nas a2200205 4500008004100000022001400041245009900055210006900154260000800223300001100231490000700242520120600249653002101455653001301476653001401489653002301503100001501526700002301541856012501564 2023 eng d a1674-200100aSettling and spreading behaviour of particle clusters in quiescent liquids in confined vessels0 aSettling and spreading behaviour of particle clusters in quiesce cDEC a91-1000 v833 a

Here we report experiments on particle cluster settling at high Reynolds number in quiescent liquid contained in a vessel. The particles were observed to spread at the vessel bottom surface in a nearcircular annular shape after settling irrespective of the shape of the vessel cross-section and particle shape, size, and types. Effect of different parameters such as mass, type and aspect ratio of the particles, height, and viscosity of liquid was investigated on spreading behaviour. Formation of the hemispherical bottom cap of the cluster that bounces upon hitting the vessel bottom surface was found to be responsible for the final circular annular shape of the settled structure. Particle leakage from the cluster was seen in the form of a tail. In the liquid having viscosity beyond 100 cP, cluster breakage was observed that resulted in hindered settling and asymmetric shapes of finally settled particles. The observations are useful to understand the overall area over which settling and spreading of such clusters can be observed. (c) 2023 Published by Elsevier B.V. on behalf of Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences.

10aParticle cluster10aSettling10aspreading10aTemporal evolution1 aPal, Sayan1 aKulkarni, Amol, A. uhttps://library.ncl.res.in/content/settling-and-spreading-behaviour-particle-clusters-quiescent-liquids-confined-vessels02155nas a2200205 4500008004100000022001400041245011300055210006900168260000900237300001400246490000600260520141100266100002601677700002501703700002501728700002701753700002101780700002301801856012501824 2024 eng d a2058-988300aScaling-up continuous production of mesoporous silica particles at kg scale: design & operational strategies0 aScalingup continuous production of mesoporous silica particles a cJUN  a1914-19230 v93 a

This paper demonstrates a continuous flow pilot-scale production of highly porous mesoporous silica particles (MSPs) via a soft template based technique. The study presents pilot scale reactor design, fabrication and production of mesoporous silica particles with a 1 kg per day production rate. The extent of mixing and overall performance of the system were evaluated by conducting a hydrodynamic study, including the estimation of the heat transfer coefficient and dispersion number. Nanoparticle synthesis in a clogging-free manner is the key challenge in moving towards large scale production and commercial applications. This article presents a comprehensive study on the effect of key parameters for successful scaling up of the process. We have also addressed challenges faced and how these are overcome by troubleshooting the process. Different strategies were used to prevent the clogging of the reactor, which involved reactant dilution, periodic pulsation and slug flow (two phase flow). Among them, slug flow allows us to operate the reactor continuously for several hours without clogging and wall-deposition problems. It helped produce morphologically well-defined and near-monodisperse particles. With this process, the production is validated at a scale of 85 times compared to that of a laboratory system (from 22 mL to >1.5 L), enabling a production rate of 20-50 g h(-1).

1 aJundale, Rajashri, B.1 aSonawane, Jayesh, R.1 aPalghadmal, Anil, V.1 aJaiswal, Hemant, Kumar1 aDeore, Hital, S.1 aKulkarni, Amol, A. uhttps://library.ncl.res.in/content/scaling-continuous-production-mesoporous-silica-particles-kg-scale-design-operational02400nas a2200157 4500008004100000022001400041245011600055210006900171260000800240300001400248490000700262520180000269100002402069700002302093856012602116 2026 eng d a0888-588500aSelection of tubular reactor configurations for a confined space: analysis of space-fillingness and performance0 aSelection of tubular reactor configurations for a confined space cMAR a5239-52580 v653 a

Introducing bends or coiling in a tubular reactor promotes Dean vortices, which enhance radial mixing as well as heat and mass transfer. Exploring compact geometries that strengthen curvature-induced mixing is highly beneficial for continuous flow synthesis across scales. Despite their advantages, selecting an appropriate configuration of tubular reactors in a given space (jacket) requires careful evaluation of multiple factors, including energy efficiency, dispersion behavior, heat transfer performance, and spatial compactness. This paper presents a holistic framework for selecting an optimal configuration of a tubular reactor within a confinement (jacket) based on energy efficiency, dispersion behavior, heat transfer, and spatial compactness. Ten distinct configurations are explored based on geometrical characterization and single-phase Computational Fluid Dynamics (CFD) simulations. Each configuration is evaluated for flow patterns, pressure drop, residence time distribution (RTD), and jacket-side flow distribution. The results demonstrate that geometric design, especially the number and arrangement of bends, has a pronounced impact on reactor performance, influencing both compactness and dispersion characteristics. A combined qualitative-quantitative assessment is employed, utilizing radar plots (which capture key simulation and geometric data) and a K-means clustering unsupervised learning algorithm, along with a derived performance index (Pi), to rank configurations based on their geometric attributes. This approach forms a robust basis for selection and design guidance. The study indicates that while individual designs offer specific advantages, coil geometries such as multihelix, spiral, and elongated spirals deliver optimal overall performance.

1 aMali, Chaitanya, R.1 aKulkarni, Amol, A. uhttps://library.ncl.res.in/content/selection-tubular-reactor-configurations-confined-space-analysis-space-fillingness-and