R-3 Repository :: Browsing by Author "Biswal, Sibani Lisa"

Browsing by Author "Biswal, Sibani Lisa"

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A Multi-scale Study of Carbonate Wettability Alteration: A Route to “Smart Water”
(2019-12-05) Song, Jin; Hirasaki, George; Biswal, Sibani Lisa
“Smart water” refers to the low-salinity brine that can alter wettability and enhance oil recovery. The injection of “smart water” as a low-cost enhanced oil recovery (EOR) approach has drawn increasing attentions in the oil and gas industry. Particularly, the “smart water” EOR has promising applications in oil-wet, naturally fractured carbonate reservoirs where capillary imbibition is extremely important. Successes of “smart water” in carbonate systems have been reported in both laboratory flooding experiments and a field-scale pilot. However, underlying mechanism of the “smart water”-induced wettability alteration in carbonates remains unclear. Therefore, this dissertation systematically investigates the wettability alteration process of carbonate rocks in “smart water”. The first objective of this work is to understand the electrostatic interactions between carbonate rocks and oils. In particular, the surface charge of carbonate minerals in brines has been a focus of literature research because it is generally believed to govern the surface wettability. To model the formation of surface charge, surface complexation models (SCM) are developed based on rock-ion complexations. A SCM was first developed for pure calcite, the primary component of carbonate rocks, in Chapter 3. Divalent ions Ca2+, Mg2+, CO32-, and SO42- are found to bind much more strongly to the calcite than monovalent ions. The equilibrium constants for binding reactions are also found to negatively correlate to the hydrated ion radius for ions of the same charge. Moreover, the weak potential determining ion Na+ is found to significantly contribute to the positive charge of calcite in high-salinity brines (5M NaCl). The synthetic calcite SCM was then extended to work for natural carbonates with surface impurities in Chapter 4. Three carbonate rocks, Iceland spar, Indiana limestone, and “SME” reservoir rock, were investigated. The effects of inorganic impurity silica and organic impurities are examined individually in the model calculation. Both the silica surface binding reactions and the organic acids surface coverage (%) are included in the extended model. The SCM successfully fits all 63 zeta potential data of synthetic calcite and three natural carbonates in various mixed-electrolyte brines with varying ionic strengths and CO2 partial pressures. The organic impurities are found to play the dominant role in making the natural carbonates more negatively charged than synthetic calcite. Humic acids extracted from a humus sample were used to treat the synthetic calcite sample in an experiment. The treated calcite had a significantly more negative zeta potential, demonstrating the effect of organic impurities on the carbonate surface charge. The second objective of this work is to experimentally evaluate the carbonate wettability alteration in “smart water”. Spontaneous imbibition was chosen over contact angle to characterize wettability alteration due to the poor reproducibility of contact angle measurements. The effects of brine chemistry, especially Mg2+, SO42-, and salinity, were investigated in a model oil system in Chapter 5. Both the reduction in Na+ and addition of SO42- are found to contribute to wettability alteration. Mg2+ is found to be unfavorable for wettability alteration. Ca2+ is believed to facilitate SO42- with wettability alteration. Rock/brine and oil/brine zeta potentials are measured, and the electrostatic component of disjoining pressure is calculated to understand the role of electrostatics in this process. The surface concentration of charged species on the Indiana limestone surface is also analyzed based on the SCM developed in Chapter 4. The reduction of the Na+ surface complexation (>CaOH…Na+0.25) in low salinity brines is believed to be a critical mechanism responsible for wettability alteration based on the SCM calculations. In Chapter 6, the effect of oil physicochemical properties on carbonate wettability alteration was also investigated by spontaneous imbibition measurements. The results were also used to evaluate two possible wettability alteration mechanisms: rock/oil electrostatic repulsion and microdispersion formation. Seven oils were fully characterized and used in spontaneous imbibition measurements in low-salinity water. For the first time, the effectiveness of low-salinity water is found to positively correlate with the oil interfacial tension in low-salinity water. Oils with higher interfacial activity are found to respond more positively to low-salinity water. Moreover, cryogenic transmission electron microscopy (Cryo-TEM) images suggest that microdispersion is essentially macroemulsion, and its formation is an effective indicator – but not the root cause – of wettability alteration. Rock/oil electrostatic repulsion based on zeta potentials is found to be an insufficient condition for wettability alteration in carbonate minerals. Finally, low-salinity water coreflooding was performed using a crude oil that responded positively to low-salinity water in spontaneous imbibition. 41% of original oil in-place (OOIP) was recovered after the initial high-salinity water flooding. An additional 12% (of OOIP) is observed after the injection of low-salinity water. The reduction of NaCl concentration is confirmed to effectively improve oil recovery in the forced displacement experiment.
Additives to Minimize Viscosity Reduction for Borate-Crosslinked Guar under High Pressure
(2016-09-07) Alharbi, Abdulrahman Faihan A; Biswal, Sibani Lisa
Borate-crosslinked guar is commonly used in hydraulic fracturing. The stimulation process conditions occur at temperatures between100-300 °F and high pressures up to 8000 psi. The viscosity of the borate-crosslinked guar shows interesting rheological responses under the influence of mechanical shear, pH and temperature. It has been found recently that the fluids significantly decrease in their viscosity under high pressure. This process was found to be reversible and very rapid. The lab measurements illustrate that the percentage loss in viscosity of guar/borate system could reach to 97 % at 8000 psi. Thus, the fluid may loss some or all viscosity contributed by the crosslinker. This thesis focusses on the addition of novel nanoparticle-based additives which could be added to a guar/borate crosslinked gel to minimize viscosity reduction under high pressures. The additives studied are zirconium oxide, titanium oxide and cerium oxide nanoparticles. This study shows that the percentage loss in viscosity could be reduced from 97 % to only 67 % when using these additives.
Adeno-associated virus capsid as a scaffold for metal binding and nanoparticle synthesis
(2014-04-24) Dempsey, Chris; Suh, Junghae; Drezek, Rebekah A.; Biswal, Sibani Lisa
Viruses, natural biological entities that have developed complex and compact mechanisms to deliver genetic material to target cells through natural evolution, can be repurposed for new nanoscale applications in a broad range of fields, including being used as biologically relevant therapeutics. Rationally designed genetic enhancements, chemical modifications, and hybrid linkages to other nanoscale materials can make viral vectors even more attractive as cargo-carrying compounds in cells. The motley array of amino acids on the surface of a virus capsid, which contains different side chains that have certain charge, hydrophobicity, and polarity properties, can be modified in order to bind inorganic metals and other metal ions for the purpose of synthesizing new compounds. Nanoscale metal and composite nanoparticles may have unique nanoscale properties that have relevance in a biological research setting, such as providing high signal over background contrast in crowded tissue compartments, Individual viruses can function as scaffolds, providing a surface for synthesis of these inorganic nanoparticles in order to combine the advantages of each individual element into a single hybrid compound. In this thesis, I first present my efforts to study a type of inorganic nanoparticle, which has been shown to generate high contrast nonlinear optical signal for biological imaging applications. Specifically, I created a hybrid labeling and delivery system by modifying the inorganic nanoparticles with a specific polymer compound, endowing them with the ability to condense DNA as well as to enter cells to deliver a genetic payload. Next, I detail a method of producing gold nanoparticles with variable morphology and dispersity using an adeno-associated virus as a scaffold for precursor nucleation. Finally, I describe how I generated mutant virus capsids that can bind metal ions after responding to an external stimulus that causes a conformational change in capsid subunits, externalizing metal binding domains. These detailed studies of hybrid molecules show that attractive properties of individual components of these nanomaterials can be combined or leveraged in a controlled manner in order to generate new materials for biologically relevant applications in the future.
Analysis of vapor-liquid coexistence in colloidal systems
(Rice University, 2022-02-15) Biswal, Sibani Lisa; Joshi, Kedar; Chemical and Biomolecular Engineering
This data set created in 2020 describes analysis of a superparamagnetic colloidal system forced to phase separate into a liquid-vapor coexistence. The liquid clusters and bulk particles are analyzed and modeled with classical thermodynamics.
Anode battery materials and methods of making the same
(2016-05-17) Biswal, Sibani Lisa; Thakur, Madhuri; Wong, Michael S.; Sinsabaugh, Steven L.; Isaacson, Mark; Rice University; United States Patent and Trademark Office
In some embodiments, the present invention provides novel methods of preparing porous silicon films and particles for lithium ion batteries. In some embodiments, such methods generally include: (1) etching a silicon material by exposure of the silicon material to a constant current density in a solution to produce a porous silicon film over a substrate; and (2) separating the porous silicon film from the substrate by gradually increasing the electric current density in sequential increments. In some embodiments, the methods of the present invention may also include a step of associating the porous silicon film with a binding material. In some embodiments, the methods of the present invention may also include a step of splitting the porous silicon film to form porous silicon particles. Additional embodiments of the present invention pertain to anode materials derived from the porous silicon films and porous silicon particles.
Application of Foam for Mobility Control in Enhanced Oil Recovery (EOR) Process
(2014-04-24) Cui, Leyu; Hirasaki, George J.; Miller, Clarence A.; Biswal, Sibani Lisa; Alvarez, Pedro J.
This thesis focuses on the application of foam for mobility control in enhanced oil recovery (EOR) process. The performance of foam and surfactants was evaluated by systematic laboratory study. This includes the screening and evaluation of surfactant formulations for foam EOR process and the investigation of foam for mobility control at reservoir conditions. The adsorption of cationic surfactants on natural minerals was discussed in a separate chapter, although it is one aspect for evaluating surfactant formulations. A numerical model was used to fit the foam strength for foam flooding at reservoir conditions. The solubility, thermal and chemical stability and foaming ability of surfactant formulations were investigated in the screening and evaluation step. A qualified surfactant formulation for foam EOR should be soluble and stable from injection to reservoir conditions. The foaming ability of surfactant formulations needs to be verified in a porous media with crude oil. The bulk foam tests, i.e., foam height, equilibrium foam volume and foam half-life, are not suggested to be used for evaluating foaming ability of surfactant formulations, because of the poor correlation with foam tests in porous media. The detrimental effect of oil, especially for light crude oil, for foam stability was demonstrated. Foam boosters, e.g., betaine surfactants, can be used to stabilize the foam in the presence of crude oil. The mobility control ability of foam was evaluated in Silurian dolomite cores at reservoir conditions after screening and evaluation step. The apparent viscosity of foam was used to describe the mobility control ability. The higher apparent viscosity indicates the stronger foam and better mobility control ability. The strength of foam depends on foam quality, salinity and temperature. The influence of each parameter was investigated and illustrated by controlled experiments. Ethomeen C12 in formation brine and CO2 can generate strong foam at 120 °C and 3400 psi in a wide range of foam quality after the pressure gradient exceeded the minimum pressure gradient. The adsorption of cationic surfactant on the pure carbonate minerals is low owing to the repulsion of the electrostatic force. However, the natural carbonate minerals contain negatively charged impurities, e.g., silica and clays. The adsorption of cationic surfactants on these impurities was significant. Multivalent cations, i.e., Mg2+, Ca2+ and Al3+, can compete with cationic surfactants on the negatively charged binding sites to reduce the adsorption. The adsorption of Ethomeen C12 on silica was reduced from 5.33 mg/m2 in DI water to 3.31 mg/m2 in synthetic brine with 1.51×10-3 mol/L Al3+. The adsorption of Ethomeen C12 was measured at 2 atm CO2 to keep the solution clear. The method of methylene blue (MB) two-phase titration was improved to determine the cationic surfactant concentrations in high salinity brine. In summary, this study demonstrates the methodology to screen the surfactant formulations for the foam EOR process, elucidates the application of the foam for mobility control at reservoir conditions, improves the MB two-phase titration for cationic surfactant in high salinity brine and illuminates the reducing of the adsorption for cationic surfactants on natural carbonate minerals.
Application of magnetic nanoparticles as demulsifiers for surfactant-enhanced oil recovery
(Wiley, 2023) Zhang, Leilei; Bai, Chutian; Zhang, Zhuqing; Wang, Xinglin; Nguyen, Thao Vy; Vavra, Eric; Puerto, Maura; Hirasaki, George J.; Biswal, Sibani Lisa
Nonionic surfactants are increasingly being applied in oil recovery processes due to their stability and low adsorption onto mineral surfaces. However, these surfactants lead to the production of emulsified oil that is extremely stable and difficult to separate by conventional methods. This research characterizes the stability of crude oil mixed with a nonionic surfactant, L24–22, in a brine solution. When subjected to gravity separation, a middle oil-rich and bottom water-rich emulsion are generated for various water–oil ratios. Thermal treatments can effectively break oil-rich emulsions, but the bottom water layer remains contaminated with micron-sized crude oil droplets. A magnetic nanoparticle treatment is shown to demulsify the crude oil emulsions, dropping the total organic carbon (TOC) in the water layer from 1470 to 30 ppm.
Assembling magnetic colloidal particles in microfluidic devices
(2009) Xie, Weijia; Biswal, Sibani Lisa
The motivation of this research project is to assemble colloidal particles in microfluidic devices to create intelligent microstructures. We have created three types of novel structures. We have created magnetic chains consisting of hydrophobic particles functionalized with myristoleic acid. We have further formed hybrid hydrophobic hydrophilic magnetic chains by mixing particles coated with myristoleic acid and particles coated with biotin and linking them with streptavidin. Finally, we have developed hybrid ferromagnetic-paramagnetic chains with both ferromagnetic and paramagnetic particles. These chains have the ability to self assemble into specific structures due to their magnetic dipole-dipole interactions between the ferromagnetic particles. In order to precisely control the particle assembly process we have developed a microfluidic platform using pressurized reservoirs and microvalves. Combing the magnetic particle hybrid linking technology with microfluidic devices, we propose several potential methods to design and pattern segmental magnetic chains in a laminar multi-stream flow.
Characterization & Application of Immobilized Biomacromolecules using Microcantilever and QCM Sensors
(2014-04-15) Wang, Jinghui; Biswal, Sibani Lisa; Segatori, Laura; Wong, Michael S.; McDevitt, John T.; Suh, Junghae
The structure and function of immobilized biomacromolecules are likely to be altered because of the solid surface. The long-term objective of this thesis is to develop surface-based biosensors for the characterization and application of biomacromolecules at the liquid-solid interface. In this study, two analytical surface-sensitive sensors are utilized: microcantilevers and quartz crystal microbalance with dissipation (QCM-D). Each offers unique information regarding the molecules of interest. In particular, the systems that are covered in this thesis include the detection of target analytes using specific recognition elements and the characterization of supported lipid membranes. This research has led to a better understanding of the effect of solid surfaces on protein structure and function, as well as the ability to engineer biomolecular surfaces with great control. There are two detection systems that were studied: a phage-derived peptide system for the detection of pathogenic bacteria Salmonella and an antibody displacement assay for the detection of an explosive, 2,4,6-trinitrotoluene (TNT). The microcantilever responds to changes in the surface free energy on the sensor surface by monitoring changes in its deflection. The physisorption or chemisorption of molecules to the cantilever surface induces a mismatch in the surface stress, causing the cantilever to bend. The multiplexed measurement is able to quickly determine the binding affinities of various phage-derived peptides, improving the screening efficiency of the peptides derived from phage display libraries for Salmonella detection. The microcantilever-based technique provides a novel biosensor to rapidly and accurately detect pathogens and holds potential to be further developed as a screening method to identify pathogen-specific recognition elements. QCM measures mass changes on the sensor surface by monitoring the frequency change of the crystal. The combination of a competition assay with QCM using an anti-TNT antibody is able to distinguish a TNT molecule among molecules of similar structure at low concentrations, leading a sensitive and selective assay. The reliability of this method was further investigated in more real environments simulated by fertilizer solution and seawater. Furthermore, this method could be also applied in gas phase detection of TNT, as well as the detection of other chemicals, such as environmental pollutants and illegal drugs. In both of these detection assays, a mathematical model was developed to quantify the binding of the target molecules with the molecules of interest. In the second half of the thesis, the microcantilever sensor is applied to characterize supported lipid bilayers (SLBs), an interesting biomacromolecular assembly that holds great importance as a model system for membranes. Through monitoring the cantilever deflection, the formation of the SLB, its temperature induced phase transitions, and its interactions with membrane-active molecules are investigated. With increasing temperature, the lipid acyl chains transition from an ordered state to a disordered state, accompanied by a changes in the surface stress that can be readily detected using microcantilever. The phase transition temperature of SLBs is different from that of a lipid monolayer, indicating that the existence of the solid support aﬀects the monolayer structure. Two amphipathic membrane-active molecules, peptide (PEP1) and a triblock copolymer (Pluoronic), are studied for their associations with SLBs. PEP1’s association with SLBs highly depends on the ratio of peptide over lipid, while the Pluoronic interacts with SLBs as a function of temperature and the length of lipophilic block in the copolymer. Therefore, the microcantilever sensor is capable of measuring the conformational change of surface-bound molecules, as well as characterizing the kinetics of membrane-peptide interactions with great sensitivity.
Characterization of switchable surfactant interactions with biomimetic surfaces
(2021-03-16) Chen, Yi-Lin; Biswal, Sibani Lisa
Amphiphiles are molecules that have both hydrophobic and hydrophilic chemical groups. Common examples of amphiphiles are surfactants, phospholipids, and block copolymers. Due to their dual chemical nature, amphiphiles readily partition to surfaces and interfaces. In the bulk phase, amphiphiles assemble into complex morphologies, such as micelles, vesicles, and lamella structures, to reduce the system free energy. They are widely utilized in different industries such as consumer products, detergents, pharmaceutical drug delivery agents, food science, and oil recovery. Several interfacial interactions have been studied, including amphiphile adsorption or desorption onto substrates, and amphiphile-amphiphile interactions. Recently, switchable surfactants have been reported as an interesting class of amphiphiles that could change their chemical or physical properties when triggered by stimuli, such as pH or light. These are utilized in a variety of applications such as cargo delivery and release and as viscoelastic rheological fluids. However, the underlying mechanism of the behavior of switchable surfactants with surfaces and interfaces remains unclear. Thus, this dissertation systematically investigates how switchable surfactants interact with interfaces by utilizing different surface characterization techniques, including quartz crystal microbalance with dissipation (QCM-D), zeta potential measurements and surface tension measurements. First, the interaction between the switchable surfactant, DTTM (N,N,N' trimethyl-N'-tallow-1,3- diaminopropane), and a silica substrate is investigated. Our results showed that the adsorption is the function of ionic strength and pH of the solution. A two-step adsorption model was applied to characterize DTTM adsorption when above its critical micelle concentration (CMC) while a Langmuir model was used to describe the adsorption when its concentration is below CMC. Next, another switchable surfactant, MSDH (O-methyl-serine dodecylamide hydrochloride), and its interaction with a biomimetic phospholipid membrane, is studied. Two morphologies of phospholipid membrane, liposomes and supported lipid bilayers, were used to understand the governing interactions between MSDH and lipid membranes. Our results suggest that the underlying mechanism for membrane lysis by MSDH differs from the commonly described three-step model used to describe membrane lysis by amphiphiles. Lastly, surface characterization platforms developed for these switchable surfactants are applied to study the interaction between exosomes and lipid bilayers. Exosomes are cell-derived vesicles, which contain protein, RNA, as well as other genetic material, and have been considered to assist with intracellular communication and cargo delivery. However, an understanding of how exosomes pass through the cell membrane remains unclear. From our characterization platform, our results suggest new insights into how cells uptake exosomes. When combined, this thesis provides a systematic platform to study the interactions between complex amphiphiles and interfaces. This dissertation also provides new insights and models to explain how solution conditions alter the interactions of switchable surfactants with interfaces.
Characterizing Asphaltene Deposition in the Presence of Chemical Dispersants in Porous Media Micromodels
(American Chemical Society, 2017) Lin, Yu-Jiun; He, Peng; Tavakkoli, Mohammad; Mathew, Nevin Thunduvila; Fatt, Yap Yit; Chai, John C.; Goharzadeh, Afshin; Vargas, Francisco M.; Biswal, Sibani Lisa
Asphaltenes are components in crude oil known to deposit and interrupt flows in critical regions during oil production, such as the wellbore and transportation pipelines. Chemical dispersants are commonly used to disperse asphaltenes into smaller agglomerates or increase asphaltene stability in solution with the goal of preventing deposition. However, in many cases, these chemical dispersants fail in the field or even worsen the deposition problems in the wellbores. Further understanding of the mechanisms by which dispersants alter asphaltene deposition under dynamic flowing conditions is needed to better understand flow assurance problems. Here, we describe the use of porous media microfluidic devices to evaluate how chemical dispersants change asphaltene deposition. Four commercially used alkylphenol model chemical dispersants are tested with model oils flowing through porous media, and the resulting deposition kinetics are visualized at both the matrix scale and pore scale. Interestingly, initial asphaltene deposition worsens in the presence of the tested dispersants, but the mechanism by which plugging and permeability reduction in the porous media varies. The velocity profiles near the deposit are analyzed to further investigate how shear forces affect asphaltene deposition. The deposition tendency is also related to the intermolecular interactions governing the asphaltene–dispersant systems. Furthermore, the model system is extended to a real case. The use of porous media microfluidic devices offers a unique platform to develop and design effective chemical dispersants for flow assurance problems.
Characterizing Asphaltene Related Flow Assurance Problems with Microfluidics
(2022-04-22) Zhang, Zhuqing; Biswal, Sibani Lisa
Asphaltene deposition and emulsion plugging are significant contributors to oil production and transportation flow assurance problems. A better understanding of the physicochemical aspects of asphaltenes, such as their interfacial and transport properties, is required to better design industrial macroscale processes. Microfluidics has emerged as a new method to evaluate complex fluid flow in confined geometries. Also, microfluidic devices can capture the critical characteristics of reservoir rocks and provide novel insights into the transport, reactions, and chemical interactions governing fluids used in the oil and gas industry. Dual-perm and natural porous mimic microfluidic designs are applied to represent various flow conditions typically found in oil flow processes. High efficient, economically feasible solutions, including non-toxic microemulsion formulations, polymer-grafted nanoparticles, and chemical inhibitors, are designed for asphaltene mitigation and remediation. Furthermore, the organization of asphaltenes on interfaces is studied, using asphaltene mimic molecules as a comparison to natural asphaltenes to better understand emulsion stability. We provide insight to better design industrial treatment for crude oil demulsification and oil-water separation through a deeper understanding of asphaltene behaviors at interfaces.
Characterizing Nonlinear Dynamics with Stochasticity Using Semiflexible Paramagnetic Colloidal Filaments
(2019-04-19) Zhao, Jingjing; Biswal, Sibani Lisa
Elastic Brownian filaments exhibit rich dynamics that are essential in numerous biological and industrial processes, such as intracellular transport and flagellar motion in biology, processing of rod-like polymers, and other rheological phenomena found in soft matter systems. Single filament scale research is needed to better understand these dynamics. One common theme governing these systems is non-linear dynamics as a result of the competition between the elastic and viscous forces acting on the filament, with thermal energy oftentimes adding stochasticity to the dynamics. This has resulted in behavior that cannot be simply explained by mechanical force balances. In this work, we investigate the two-dimensional dynamics of a semiflexible filament on the low-Reynolds number regime using experimental, theoretical and numerical methods. Experimentally, we synthesize DNA-linked superparamagnetic colloidal filaments and apply them as models for inextensible semiflexible filaments under various external fields. Theoretically, we utilize a worm-like chain model and slender-body theory to provide scaling and other analytical insights. A bead-spring chain model Brownian dynamics simulation is utilized to provide a numerical approach to support the experimental and theoretical results. Applying these methods, we study the model filament dynamics induced by two force fields: magnetic and gravitational fields. Firstly, the filament is induced to bend and buckle using an orthogonal magnetic field. The limits of linear elastic bending observed within an experimental regime is identified. Various non-linear dynamical stages leading to a higher-order filament buckling and configurational instabilities are examined. The inhomogeneous temporal evolution of the buckling wavelength is analyzed and the contractions under various conditions are compared. Secondly, a gravitational field is applied to semiflexible filaments. The configurational transitions and sediment dynamics of the model filament is studied in an otherwise quiescent fluid. The effect of thermal fluctuations on the stochasticity of the filament configurations and orientations is investigated. We also consider the settling dynamics of the semiflexible filament in more confined geometries, such as a post array, where interactions between the filament and post influence the migration path. This thesis advances our understanding of the multitude of configurations and non-linear dynamics of semiflexible colloidal filaments induced by external forces and under the influence of thermal fluctuations. This body of work will contribute to the development of novel soft materials as well as providing new insights of the properties of related filament systems.
Characterizing the spatiotemporal evolution of paramagnetic colloids in time-varying magnetic fields with Minkowski functionals
(Royal Society of Chemistry, 2020) Hilou, Elaa; Joshi, Kedar; Biswal, Sibani Lisa
Phase separation processes are widely utilized to assemble complex fluids into novel materials. These separation processes can be thermodynamically driven due to changes in concentration, pressure, or temperature. Phase separation can also be induced with external stimuli, such as magnetic fields, resulting in novel nonequilibrium systems. However, how external stimuli influence the transition pathways between phases has not been explored in detail. Here, we describe the phase separation dynamics of superparamagnetic colloids in time-varying magnetic fields. An initially homogeneous colloidal suspension can transition from a continuous colloidal phase with voids to discrete colloidal clusters, through a bicontinuous phase formed via spinodal decomposition. The type of transition depends on the particle concentration and magnitude of the applied magnetic field. The spatiotemporal evolution of the microstructure during the nucleation and growth period is quantified by analyzing the morphology using Minkowski functionals. The characteristic length of the colloidal systems was determined to correlate with system variables such as magnetic field strength, particle concentration, and time in a power-law scaling relationship. Understanding the interplay between particle concentration and applied magnetic field allows for better control of the phases observed in these magnetically tunable colloidal systems.
Coalescence of Model Asphaltene-Stabilized Water-in-Oil Emulsions in Microfluidic Devices
(2018-04-20) Zhang, Zhuqing; Biswal, Sibani Lisa
Asphaltene related problems have aroused more and more attention in flow assurance and proved to be fatal with practical examples in both oil production and transportation. Asphaltene-stabilized emulsions generated in the oil recovery would significant increase oil viscosity which leads to a giant energy loss during the transport process. Meanwhile, oil sources containing emulsions need extra treatments to separate residual water before being converted to petrochemical products. In order to find better solutions to breaking those unexpected emulsions sufficiently, detailed information about asphaltene-stabilized emulsions was needed. Since the chemical structure of asphaltene was still buried in mystery, we decided to utilize model molecules to mimic the field asphaltene molecules at oil-water interface, and try to investigate the mechanism of how asphatlenes stabilize emulsions. In this work, model molecules, coronene and VO-79, were used as references, and emulsion stability was characterized using microfluidic method. Interfacial properties of model asphaltene molecules were also studied with interfacial tension (IFT) measurement and surface potential measurement.
Coiling of semiflexible paramagnetic colloidal chains
(Royal Society of Chemistry, 2023) Spatafora-Salazar, Aldo; Kuei, Steve; Cunha, Lucas H.P.; Biswal, Sibani Lisa
Semiflexible filaments deform into a variety of configurations that dictate different phenomena manifesting at low Reynolds number. Harnessing the elasticity of these filaments to perform transport-related processes at the microfluidic scale requires structures that can be directly manipulated to attain controllable geometric features during their deformation. The configuration of semiflexible chains assembled from paramagnetic colloids can be readily controlled upon the application of external time-varying magnetic fields. In circularly rotating magnetic fields, these chains undergo coiling dynamics in which their ends close into loops that wrap inward, analogous to the curling of long nylon filaments under shear. The coiling is promising for the precise loading and targeted transport of small materials, however effective implementation requires an understanding of the role that field parameters and chain properties play on the coiling features. Here, we investigate the formation of coils in semiflexible paramagnetic chains using numerical simulations. We demonstrate that the size and shape of the initial coils are governed by the Mason and elastoviscous numbers, related to the field parameters and the chain bending stiffness. The size of the initial coil follows a nonmonotonic behavior with Mason number from which two regions are identified: (1) an elasticity-dependent nonlinear regime in which the coil size decreases with increasing field strength and for which loop shape tends to be circular, and (2) an elasticity-independent linear regime where the size increases with field strength and the shape become more elliptical. From the time scales associated to these regimes, we identify distinct coiling mechanisms for each case that relate the coiling dynamics to two other configurational dynamics of paramagnetic chains: wagging and folding behaviors.
Combined interfacial shear rheology and microstructure visualization of asphaltenes at air-water and oil-water interfaces
(The Society of Rheology, 2018) Lin, Yu-Jiun; Barman, Sourav; He, Peng; Zhang, Zhuqing; Christopher, Gordon F.; Biswal, Sibani Lisa
Asphaltenes are surface-active polyaromatic molecules in crude oil that are known to deposit in pipelines or stabilize water droplets by flocculating at interfaces resulting highly viscous emulsions, leading to significant flow assurance problems. Commercial dispersants have been developed to disturb asphaltene aggregation to mitigate deposition, but their role on the interfacial properties of asphaltene films is unclear. In this study, we elucidate asphaltene interfacial rheology at air-water and oil-water interfaces at high and low asphaltene surface coverage and in the presence of dispersants. A modified Langmuir trough with double-wall ring rheometer is used to simultaneously visualize the microstructure of asphaltene interface and measure the rheological responses. Two surface coverages, 0.5 and 4 μg cm−2, show widely different rheological responses at air-water interfaces. Strong yielding behavior was observed for higher coverage while a less yielding behavior and wider linear viscoelastic regime were observed for the lower coverage. Additionally, asphaltenes at decane-water interfaces were less shear-thinning than at air-water interfaces. Surface pressure-area compression-expansion curves show that the interface is more compressible in the presence of commercial chemical dispersants. This combined imaging and interfacial rheology platform provide an effective method to correlate asphaltene microstructure to interfacial rheological properties.
Deformation Dynamics of Wet Foams and Bubbles in Wide Microfluidic Channels
(2019-08-09) Vecchiolla, Daniel J; Biswal, Sibani Lisa
A prominent feature of microfluidics is the ability to generate monodisperse bubbles (or droplets) of tunable volumes and densities, which rapidly self-order under the confinement of the channels. The geometric and hydrodynamic controllability of these systems enables the precise handling and manipulation of the fluids to foster the plastic deformation of crystalline foam and bubble-bubble pinch-off using wide (>1000 μm) channels. Densely packed wet foam was subjected to expansion-contraction flow to study localized plastic deformation events from extensional and compressive stresses within the monodisperse bubble matrix. Dislocations cyclically reflected in tension or compression with disparate mechanisms in two independent rearrangement zones. The relationship between structures resembling the Inverse-Stone-Wales (ISW) defect and the partially dissociated ISW defect of graphene was examined in the model foam. An extended expansion region to force the flowing crystal out of long-range order to investigate 2-D phase transitions (i.e. melting and recrystallization) could be a promising area of future research. Symmetric and asymmetric expansions were utilized for promoting systematic bubble-bubble pinch-off to produce segregated, mono- and bidisperse bubbles at capacities exceeding 10,000 bubbles per second. The pinch-off dynamics demonstrate that bubbles split from the confinement of a “pincher” bubble and “wall” bubble, in connection with pore-level breakup mechanisms previously discovered by our lab. The wall bubble was shown to modulate the fluidic resistance in an asymmetric expansion, allowing the fragmented bubble size ratio to be adjusted by tuning the size of the bubbles formed upstream. Consequently, the system acts as a generator of ordered bi- or tridisperse foam that can be employed to study dynamic bubble interactions (e.g. coarsening) and ordered, multidisperse foam deformation. Cross-shaped surface energy wells with comparable in-plane dimensions to the initially trapped bubbles were employed to study the interactions between a large trapped bubble and the smaller monodisperse bubbles of the surrounding foam including diffusive gas exchange, bubble-bubble breakup and large bubble migration.
Developing Dirhodium-Complexes for Protein Inhibition and Modification & Copper-Catalyzed Remote Chlorination of Alkyl-Hydroperoxides
(2013-09-16) Kundu, Rituparna; Ball, Zachary T.; Marti, Angel A.; Biswal, Sibani Lisa
The work describes the development of a new class of protein-inhibitors for protein-protein interactions, based on metallopeptides comprised of a dirhodium metal center. The metal incorporation in the peptide sequence leads to high increase in binding affinity of the inhibitors. The source of this strong affinity is the interaction of histidine on the protein surface with the rhodium center. In addition to this work, rhodium-based small molecule inhibitors for FK-506 binding proteins are investigated. Also, methodology for rhodium-catalyzed modification of proteins containing surface cysteine has been developed where a simple rhodium(II) complex catalyzes cysteine modification with diazo reagents. The reaction is marked by clean cysteine selectivity and mild reaction conditions. The resulting linkage is significantly more stable in human plasma serum, when compared to common maleimide reagents. Apart from this body of work in chemical-biology, the thesis contains the discussion of development of copper-catalyzed remote chlorination of alkyl hydroperoxides. The atom transfer chlorination utilizes simple ammonium chloride salts as the chlorine source and the internal redox process requires no external redox reagents.
Directing Assembly of DNA-Coated Colloids with Magnetic Fields To Generate Rigid, Semiflexible, and Flexible Chains
(American Chemical Society, 2014) Byrom, Julie; Han, Patric; Savory, Michael; Biswal, Sibani Lisa
We report the formation of colloidal macromolecules consisting of chains of micron-sized paramagnetic particles assembled using a magnetic field and linked with DNA. The interparticle spacing and chain flexibility were controlled by varying the magnetic field strength and the linker spring constant. Variations in the DNA lengths allowed for the generation of chains with an improved range of flexibility as compared to previous studies. These chains adopted the rigid-rod, semiflexible, and flexible conformations that are characteristic of linear polymer systems. These assembly techniques were investigated to determine the effects of the nanoscale DNA linker properties on the properties of the microscale colloidal chains. With stiff DNA linkers (564 base pairs) the chains were only stable at moderate to high field strengths and produced rigid chains. For flexible DNA linkers (8000 base pairs), high magnetic field strengths caused the linkers to be excluded from the gap between the particles, leading to a transition from very flexible chains at low field strengths to semiflexible chains at high field strengths. In the intermediate range of linker sizes, the chains exhibited predictable behavior, demonstrating increased flexibility with longer DNA linker length or smaller linking field strengths. This study provides insight into the process of directed assembly using magnetic fields and DNA by precisely tuning the components to generate colloidal analogues of linear macromolecular chains.

Browsing by Author "Biswal, Sibani Lisa"

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