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Chen L, Guo C, Tao X, Ding X, Zhang K, Zhang C, Chen Q, Zheng Y, Li M, Zhang H, Xiong Y, Guan Y, Wu Z, Tian Y, Liu G. Structures of Liquid-Liquid Interfaces in Partially Miscible Systems Revealed by Soft X-ray Imaging. J Phys Chem Lett 2024; 15:8265-8271. [PMID: 39106046 DOI: 10.1021/acs.jpclett.4c01807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/07/2024]
Abstract
The properties of liquid-liquid interfaces are intricately linked to its structure, with a particular focus on the concentration distribution within the interface. To obtain precise information regarding the concentration distribution, we have developed a high-resolution soft X-ray imaging method for liquid-liquid interfaces. This work focused on representative partially miscible systems, analyzing the interfacial concentration distribution profiles of water-alkanols under both steady-state and dynamic processes, and obtaining the diffusion coefficients of different water concentrations in alkanols. Significant disparities in concentration distributions and the concentration-related diffusion coefficients were observed despite comparable diffusion distances within the same system across different states. Meanwhile, it was found that alkanols exhibit adsorption phenomena at the interface. This newfound knowledge serves as a crucial stepping stone toward a deeper understanding of partially miscible systems. Our study opens a way to explore liquid-liquid interface information with high-resolution.
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Affiliation(s)
- Lijuan Chen
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Chenfei Guo
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Xiayu Tao
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Xu Ding
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Kuanqiang Zhang
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Chao Zhang
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Qiang Chen
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yutong Zheng
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Meng Li
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Haonan Zhang
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Ying Xiong
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Yong Guan
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Zhao Wu
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Yangchao Tian
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
| | - Gang Liu
- University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230026, China
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Shrivastava S, Upadhyay A, Pradhan SS, Saha S, Singh A. Evolution Kinetics of Stabilizing Pickering Emulsion by Brush-Modified Janus Particles: DPD Simulation and Experimental Insights. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:13920-13934. [PMID: 38809114 DOI: 10.1021/acs.langmuir.4c01083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
In the present study, we report the evolution of stabilizing Pickering emulsions using brush-modified Janus particles (JPs), utilizing the dissipative particle dynamics (DPD) simulation technique. Our results are subsequently corroborated with experimental findings. Each JP has one-half of the hydrophobic surface, with the other half embedded with hydrophilic polymer brushes grown via atom transfer radical polymerization (ATRP). Our generic simulation model analyzes the chemical kinetics of polymer brush growth on one-half of the initiator-embedded microparticle (MP) surface, resulting in the formation of JP. This involves evaluating monomer conversion and reaction rates. Our results exhibit a substantial influence of the number of JPs, grafted brush density, and brush length on oil-in-water emulsion stability. We studied the evolution kinetics and stability of emulsion formation by analyzing the growth of average domain size and corresponding scaling functions up to a late time limit. This study aims to clarify the connection between the size, quantity, and functionality of JPs and the stability of Pickering emulsions.
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Affiliation(s)
- Samiksha Shrivastava
- Department of Physics, Indian Institute of Technology (BHU), Varanasi 221005, Uttar Pradesh, India
| | - Ashank Upadhyay
- Department of Material Science and Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India
| | | | - Sampa Saha
- Department of Material Science and Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Awaneesh Singh
- Department of Physics, Indian Institute of Technology (BHU), Varanasi 221005, Uttar Pradesh, India
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Wang Y, Zhu Y, Gupta P, Singamaneni S, Lee B, Jun YS. The Roles of Oil-Water Interfaces in Forming Ultrasmall CaSO 4 Nanoparticles. ACS APPLIED MATERIALS & INTERFACES 2024; 16:29390-29401. [PMID: 38787535 DOI: 10.1021/acsami.4c02256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
In natural and engineered environmental systems, calcium sulfate (CaSO4) nucleation commonly occurs at dynamic liquid-liquid interfaces. Although CaSO4 is one of the most common minerals in oil spills and oil-water separation, the mechanisms driving its nucleation at these liquid-liquid interfaces remain poorly understood. In this study, using in situ small-angle X-ray scattering (SAXS), we examined CaSO4 nucleation at oil-water interfaces and found that within 60 minutes of reaction, short rod-shaped nanoparticles (with a radius of gyration (Rg) of 17.2 ± 2.7 nm and a length of 38.2 ± 5.8 nm) had formed preferentially at the interfaces. Wide-angle X-ray scattering (WAXS) analysis identified these nanoparticles as gypsum (CaSO4·2H2O). In addition, spherial nanoparticles measuring 4.1 nm in diameter were observed at oil-water interfaces, where surface-enhanced Raman spectroscopy (SERS) revealed an elevated pH compared to the bulk solution. The negatively charged oil-water interfaces preferentially adsorb calcium ions, collectively promoting CaSO4 formation there. CaSO4 particle formation at the oil-water interface follows a nonclassical nucleation (N-CNT) pathway by forming ultrasmall amorphous spherical particles which then aggregate to form intermediate nanoparticles, subsequently growing into nanorod-shaped gypsum. These findings of this study provide insights into mineral scaling during membrane separation and can inform more efficient oil transport in energy recovery systems.
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Affiliation(s)
- Ying Wang
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Yaguang Zhu
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Prashant Gupta
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St Louis, Missouri 63130, United States
| | - Srikanth Singamaneni
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St Louis, Missouri 63130, United States
| | - Byeongdu Lee
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Young-Shin Jun
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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Das A, Musharaf Ali S. Structure and dynamics of dissociated and undissociated forms of nitric acid and their implications in interfacial mass transfer: insights from molecular dynamics simulations. Phys Chem Chem Phys 2024; 26:6916-6938. [PMID: 38334446 DOI: 10.1039/d3cp05622h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Nitric acid (HNO3) is widely used in various chemical and nuclear industries. Therefore, it is important to develop an understanding of the different forms of nitric acid for its practical applications. Molecular dynamics (MD) simulation is one of the best tools to investigate the behavior of concentrated nitric acid in aqueous solution with various forms together with pure nitric acid to identify a suitable model of nitric acid for use in simulations of biphasic systems for interfacial mass transfer. The Mulliken partial charge embedded OPLS-AA force field was used to model the neutral nitric acid, hydronium ion and nitrate ion, and it was found that the Mulliken partial charge embedded force field works quite well. The computed density of the dissociated and mixed-form acid was in good agreement with the experimental values. In water, the HNO3 molecule was seen to be coordinated with three water molecules in the first sphere of coordination. The distribution of water surrounding the HNO3 molecule and nitrate ion was corroborated by the DFT-optimized hydrated cluster. The calculated diffusivity values of the neutral acid and ions were significantly higher in the mixed form of nitric acid, which is an important dynamic quantity controlling the kinetics of the liquid-liquid interfacial extraction. The structural analysis revealed that the local aggregation is minimized when both forms of acid are present together in the solution. The water-ion and water-neutral acid interactions were predicted to be enhanced, as confirmed by H-bond studies. The shear viscosity of the mixed acid exhibited excellent agreement with the experimental values, which again confirms the consideration of the mixed form of nitric acid. The simulated value of surface tension for the mixed form of acid also appeared to be quite accurate based on the surface tension of water. The mixed form of nitric acid comprising both forms of acid is the best representation for nitric acid to be considered for MD simulations of biphasic systems. The mixed form of nitric acid established that the concentrated nitric acid may not be present either in the fully dissociated form or fully undissociated form in the solution.
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Affiliation(s)
- Arya Das
- Nuclear Recycle Board, Bhabha Atomic Research Centre, Mumbai, 400094, India
- Homi Bhabha National Institute, Mumbai, 400094, India.
| | - Sk Musharaf Ali
- Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
- Homi Bhabha National Institute, Mumbai, 400094, India.
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Hrahsheh F, Wilemski G. Effects of molecular size and orientation on the interfacial properties and wetting behavior of water/ n-alkane systems: a molecular-dynamics study. Phys Chem Chem Phys 2023; 25:5808-5816. [PMID: 36744733 DOI: 10.1039/d2cp05735b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Molecular dynamics simulations (MD) are performed to study the interfacial structure/tension and wetting behavior of water/n-alkane systems (water/nC5 to water/nC16 where nCx = CxH(2x + 2)). In particular, we study complete-to-partial wetting transitions by changing the n-alkane chain length (NC) at a constant temperature, T = 295 K. Simulations are carried out with a united-atom TraPPE model for n-alkanes and the TIP4P-2005 model of water. Simulation results are in excellent agreement with the initial spreading coefficients and contact angles calculated using experimental values of the surface and interfacial tensions. In addition, it has been determined that water/(nC5-nC7) and water/(nC8-nC16), respectively, exhibit complete and partial initial wetting modes. Simulations show that the interfacial structures of water/(nC5-nC7) are different from water/(nC8-nC16) systems. In the latter, water preferentially orients near the interface to increase the number of hydrogen bonds and the charge and mass densities. Moreover, the orientation of n-alkane molecules at water/(nC8-nC16) interfaces has a long-range persistence, resulting in layered structures that increase with NC. In addition, simulation results of the orientational order parameter Sz show alignment behavior of the n-alkane molecules with respect to the interfaces. Simulations predict that the central segments of n-alkane are strongly packed in the interfaces while the end segments (methyl groups) form smaller peaks in the outer edge of the layer. This observation confirms the "horseshoe" or "C-shaped" structure of n-alkane molecules in the water/n-alkane interfaces. At constant temperature, the interface widths of both water and the n-alkanes decrease with increasing n-alkane molecular length. These results suggest that increasing the n-alkane chain length affects the water/n-alkane interfacial properties in a manner similar to that of cooling.
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Affiliation(s)
- Fawaz Hrahsheh
- Higher Colleges of Technology, ETS, MZWC, Abu Dhabi, 58855, United Arab Emirates.
| | - Gerald Wilemski
- Department of Physics, Missouri University of Science and Technology, Rolla, MO 65409, USA.
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Numin MS, Hassan A, Jumbri K, Ramli A, Borhan N. Interfacial tension reduction mechanism by alkaline-surfactant-polymer at oil-water interface from experimental and molecular dynamics approaches. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Zheng W, Ma Z, Sun W, Zhao L. Target High‐efficiency Ionic Liquids to Promote
H
2
SO
4
‐catalyzed
C4
Alkylation by Machine Learning. AIChE J 2022. [DOI: 10.1002/aic.17698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Weizhong Zheng
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering East China University of Science and Technology Shanghai China
| | - Zhihong Ma
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering East China University of Science and Technology Shanghai China
| | - Weizhen Sun
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering East China University of Science and Technology Shanghai China
| | - Ling Zhao
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering East China University of Science and Technology Shanghai China
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Das A, Ali SM. Deciphering the curved profile of uranyl ions at the aqueous-organic interface by atomistic simulations. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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10
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Cunha RDD, Maciel CD, Homem-de-Mello P. The cooperative effect between cyclic naphthenic acids and surfactant enhances the separation efficiency. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Sarkar S, Rajeswari S, Suresh A, Sivaraman N. Hydrodynamic Properties of Tris(2-methylbutyl) Phosphate and Tri-n-alkyl Phosphates in n-Dodecane – A Comparative Investigation between Unirradiated and Gamma Irradiated Solvent Systems. SOLVENT EXTRACTION AND ION EXCHANGE 2021. [DOI: 10.1080/07366299.2021.1972648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Subramee Sarkar
- Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, India
| | - S. Rajeswari
- Analytical Chemistry & Spectroscopy Division, IGCAR, Kalpakkam, India
| | - A. Suresh
- Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, India
| | - N. Sivaraman
- Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, India
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Does uranyl-TBP complex formation happen at the aqueous-organic interface? Revelation by molecular dynamics simulations. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Rabani R, Sadafi H, Machrafi H, Abbasi M, Haut B, Dauby P. Influence of evaporation on the morphology of a thin film of a partially miscible binary mixture. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2020.126001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Dwadasi BS, Goverapet Srinivasan S, Rai B. Interfacial structure in the liquid-liquid extraction of rare earth elements by phosphoric acid ligands: a molecular dynamics study. Phys Chem Chem Phys 2020; 22:4177-4192. [PMID: 32040116 DOI: 10.1039/c9cp05719f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Solvent extraction (SX), wherein two immiscible liquids, one containing the extractant molecules and the other containing the solute to be extracted are brought in contact to effect the phase transfer of the solute, underpins metal extraction and recovery processes. The interfacial region is of utmost importance in the SX process, since besides thermodynamics, the physical and chemical heterogeneity at the interface governs the kinetics of the process. Yet, a fundamental understanding of this heterogeneity and its implications for the extraction mechanism are currently lacking. We use molecular dynamics (MD) simulations to study the liquid-liquid interface under conditions relevant to the SX of Rare Earth Elements (REEs) by a phosphoric acid ligand. Simulations revealed that the extractant molecules and varying amounts of acid and metal ions partitioned to the interface. The presence of these species had a significant effect on the interfacial thickness, hydrogen bond life times and orientations of the water molecules at the interface. Deprotonation of the ligands was essential for the adsorption of the metal ions at the interface, with these ions forming a number of different complexes at the interface involving one to three extractant molecules and four to eight water molecules. Although the interface itself was rough, no obvious 'finger-like' water protrusions penetrating the organic phase were seen in our simulations. While the results of our work help us gain fundamental insights into the sequence of events leading to the formation of a variety of interfacial complexes, they also emphasize the need to carry out a more detailed atomic level study to understand the full mechanism of extraction of REEs from the aqueous to organic phases by phosphoric acid ligands.
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Affiliation(s)
- Balarama Sridhar Dwadasi
- TCS Research, Tata Research Development and Design Center, 54-B Hadapsar Industrial Estate, Hadapsar, Pune - 411013, Maharashtra, India.
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Das A, Ali SM. Molecular Dynamics Simulation Studies on Structure, Dynamics, and Thermodynamics of Uranyl Nitrate Solution at Various Acid Concentrations. J Phys Chem B 2019; 123:4571-4586. [PMID: 31070371 DOI: 10.1021/acs.jpcb.9b01498] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structural and dynamical characteristics of uranyl ions in an aqueous acidic environment are of immense importance in the field of nuclear fuel reprocessing. In view of that, the structural and dynamical behavior of the uranyl ion in water has been investigated by performing molecular dynamics (MD) simulations using different force fields. All the force fields have depicted similar structural and dynamical properties except the free energy of hydration where the Guilbaud-Wipff (GW) model performs well over the others. The calculated density using MD simulations is found to be in excellent agreement with the measured experimental density, which ensures the accuracy of the adopted GW force field. The calculated surface tension and shear viscosity are seen to be increased with uranyl nitrate concentrations. At a higher concentration of about 4.0 mol/L, the supersaturation effect has been captured by an inflection in the plot of surface tension and shear viscosity against concentration because of the solution heterogeneity, which was correlated by an inflection in the scattering intensity observed by performing the dynamic light scattering experiment. The binding mode of nitrate ions with the uranyl ion is found to be concentration-dependent, and at higher concentration, it is predominantly monodentate.
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Affiliation(s)
- Arya Das
- Nuclear Recycle Board , Bhabha Atomic Research Centre , Mumbai 400094 , India.,Homi Bhabha National Institute , Mumbai 400094 , India
| | - Sk Musharaf Ali
- Chemical Engineering Division , Bhabha Atomic Research Centre , Mumbai 400085 , India.,Homi Bhabha National Institute , Mumbai 400094 , India
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