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Yuan S, Yang X, Zhang N, Zhang J, Yuan S, Wang Z. Molecular insights into the adsorption and penetration of oil droplets on hydrophobic membrane in membrane distillation. WATER RESEARCH 2024; 253:121329. [PMID: 38387269 DOI: 10.1016/j.watres.2024.121329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 01/19/2024] [Accepted: 02/16/2024] [Indexed: 02/24/2024]
Abstract
Membrane fouling induced by oily substances significantly constrains membrane distillation performance in treating hypersaline oily wastewater. Overcoming this challenge necessitates a heightened fundamental understanding of the oil fouling phenomenon. Herein, the adsorption and penetration mechanism of oil droplets on hydrophobic membranes in membrane distillation process was investigated at the molecular level. Our results demonstrated that the adsorption and penetration of oil droplets were divided into four stages, including the free stage, contact stage, spreading stage, and equilibrium stage. Due to the extensive non-polar surface distribution of the polytetrafluoroethylene (PTFE) membrane (comprising 95.41 %), the interaction between oil molecules and PTFE was primarily governed by van der Waals interaction. Continuous oil droplet membrane fouling model revealed that the new oil droplet molecules preferred to penetrate into membrane pores where oil droplets already existed. The penetration of resin (a component of medium-quality oil droplets) onto PTFE membrane pores required the "pre-paving" of light crude oil. Finally, the ΔE quantitative structure-activity relationships (QSAR) models were developed to evaluate the penetration mechanism of pollutant molecules on the PTFE membrane. This research provides new insights for improving sustainable membrane distillation technologies in treating saline oily wastewater.
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Affiliation(s)
- Shideng Yuan
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Xin Yang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Na Zhang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Jiaojiao Zhang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Shiling Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, PR China
| | - Zhining Wang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China.
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Li N, Pang Y, Sun Z, Sun X, Li W, Sun Y, Zhu L, Li B, Wang Z, Zeng H. Unraveling Partial Coalescence Between Droplet and Oil-Water Interface in Water-in-Oil Emulsions under a Direct-Current Electric Field via Molecular Dynamics Simulation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:5992-6003. [PMID: 38445586 DOI: 10.1021/acs.langmuir.3c04024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
When the electric field strength (E) surpasses a certain threshold, secondary droplets are generated during the coalescence between water droplets in oil and the oil-water interface (so-called the droplet-interface partial coalescence phenomenon), resulting in a lower efficiency of droplet electrocoalescence. This study employs molecular dynamics (MD) simulations to investigate the droplet-interface partial coalescence phenomenon under direct current (DC) electric fields. The results demonstrate that intermolecular interactions, particularly the formation of hydrogen bonds, play a crucial role in dipole-dipole coalescence. Droplet-interface partial coalescence is categorized into five regimes based on droplet morphology. During the contact and fusion of the droplet with the water layer, the dipole moment of the droplet exhibits alternating increases and decreases along the electric field direction. Electric field forces acting on sodium ions and the internal interactions within droplets promote the process of droplet-interface partial coalescence. High field strengths cause significant elongation of the droplet, leading to its fragmentation into multiple segments. The migration of hydrated ions has a dual impact on the droplet-interface partial coalescence, with both facilitative and suppressive effects. The time required for droplet-interface partial coalescence initially decreases and subsequently increases as the field strength increases, depending on the competitive relationship between the extent of droplet stretching and the electric field force. This work provides molecular insights into the droplet-interface coalescence mechanisms in water-in-oil emulsions under DC electric fields.
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Affiliation(s)
- Ning Li
- College of New Energy, China University of Petroleum (East China), Qingdao 266580, China
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G1H9, Canada
| | - Yunhui Pang
- College of New Energy, China University of Petroleum (East China), Qingdao 266580, China
| | - Zhiqian Sun
- College of New Energy, China University of Petroleum (East China), Qingdao 266580, China
| | - Xiaoyu Sun
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G1H9, Canada
| | - Wangqing Li
- College of New Energy, China University of Petroleum (East China), Qingdao 266580, China
| | - Yongxiang Sun
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G1H9, Canada
| | - Liyun Zhu
- College of New Energy, China University of Petroleum (East China), Qingdao 266580, China
| | - Bin Li
- School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Zhenbo Wang
- College of New Energy, China University of Petroleum (East China), Qingdao 266580, China
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G1H9, Canada
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Javadian S, Sadrpoor SM, Khosravian M. Taking a look accurately at the alteration of interfacial asphaltene film exposed to the ionic surfactants as demulsifiers. Sci Rep 2023; 13:12837. [PMID: 37553504 PMCID: PMC10409716 DOI: 10.1038/s41598-023-39731-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 07/30/2023] [Indexed: 08/10/2023] Open
Abstract
The water droplets surrounded by a rigid interfacial asphaltene (ASP) film is one of the major setbacks in the petroleum industry. In this study, the properties of the interfacial ASP films around water droplets exposed to ionic surfactants as demulsifier were investigated. According to molecular dynamics (MD) simulation, the anionic surfactants are more effective than the cationic surfactant in the demulsification process since the anionic surfactants have the exact desire to localize not only near the ASP molecules but also near the water molecules. It has been found that it is likely to cause film changes and ruptures. Also, the MD simulation results for the desired surfactant, anionic surfactant, demonstrated that an increase in the surfactant concentration had an adverse effect on the system by hindering the change in the interfacial film. The increase in the temperature along with the enhancement in the adsorption rate of the surfactant results in the better performance of the demulsifier. Taking the MD and quantum results into account, the film deformation is a decisive factor in demulsification. The quantum computation has indicated that the electrostatic interactions play a significant role in selecting the attraction position and adsorption energy of the surfactant molecules.
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Affiliation(s)
- Soheila Javadian
- Department of Physical Chemistry, Faculty of Basic Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Islamic Republic of Iran.
| | - S Morteza Sadrpoor
- Department of Physical Chemistry, Faculty of Basic Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Islamic Republic of Iran
| | - Mahnaz Khosravian
- Department of Physical Chemistry, Faculty of Basic Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Islamic Republic of Iran.
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Li B, Ju M, Dou X, Li N, Zhang W, Sun Z, Yu K, Wang J, Wang Z. Assessing nanoparticle-surfactant-salt synergistic effects on droplet–droplet electrocoalescence by molecular dynamics simulations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Li S, Yuan S, Zhang Y, Guo H, Liu S, Wang D, Wang Y. Molecular Dynamics Study on the Demulsification Mechanism of Water-In-Oil Emulsion with SDS Surfactant under a DC Electric Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:12717-12730. [PMID: 36197725 DOI: 10.1021/acs.langmuir.2c02364] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Application of an electric field is an effective demulsification method for water-in-oil (W/O) emulsions. For the W/O emulsions stabilized by anionic surfactants, the microscopic demulsification mechanism is still not very clear. In this work, the coalescence behavior of two droplets stabilized by the anionic surfactant sodium dodecyl sulfate (SDS) in the oil phase under a DC electric field is investigated by molecular dynamics simulation. The effects of electric field strength and oil type on the electrocoalescence of two water droplets are mainly considered. The trajectory snapshots and center of mass of the two water droplets suggest that there is almost no migratory coalescence. The movement of sodium ions and SDS, which is a combined effect of the electric field force and the resistance from the oil phase, is crucial for the deformation and connection of two water droplets. The results of mean square displacement, radial distribution function, hydration number, and interaction energies of Na+-H2O and SDS-H2O indicate that the sodium ion has a stronger ability to carry water molecules for movement than SDS. The stronger electric field strength will result in more severe deformation and shorter coalescence time. Under the higher electric field strength, the two droplets will be elongated into a slender water ribbon. By applying a pulsed DC electric field with suitable amplitude, frequency, and duty ratio, it is possible to achieve full coalescence for the ionic surfactant-stabilized W/O emulsions. The oil phase also plays an important role for the deformation of droplets and the migration of emulsion components. For the different oil phases, a longer time or stronger electric field strength would be needed for the electrocoalescence of droplets in the oil phase with higher density and viscosity. Our results are expected to be helpful for practical application in the petroleum industry and chemical engineering.
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Affiliation(s)
- Shiyan Li
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Shundong Yuan
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Yuanwu Zhang
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Huiying Guo
- Research Institute of Experiment and Detection, Xinjiang Oilfield Company, PetroChina, Karamay834000, China
| | - Sai Liu
- Research Institute of Experiment and Detection, Xinjiang Oilfield Company, PetroChina, Karamay834000, China
| | - Diansheng Wang
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Yudou Wang
- College of Science, China University of Petroleum, Qingdao266580, China
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Liu W, Sun Z, Li N, Qi Z, Wang Z, Wang Z. Binary droplet interactions in shear water-in-oil emulsion: A molecular dynamics study. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Li N, Sun Z, Pang Y, Qi Z, Liu W, Li W, Sun M, Li B, Wang Z. Microscopic mechanism for electrocoalescence of water droplets in water-in-oil emulsions containing surfactant: A molecular dynamics study. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120756] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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An Optimal Subspace Deconvolution Algorithm for Robust and High-Resolution Beamforming. SENSORS 2022; 22:s22062327. [PMID: 35336498 PMCID: PMC8954155 DOI: 10.3390/s22062327] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 11/17/2022]
Abstract
Utilizing the difference in phase and power spectrum between signals and noise, the estimation of direction of arrival (DOA) can be transferred to a spatial sample classification problem. The power ratio, namely signal-to-noise ratio (SNR), is highly required in most high-resolution beamforming methods so that high resolution and robustness are incompatible in a noisy background. Therefore, this paper proposes a Subspaces Deconvolution Vector (SDV) beamforming method to improve the robustness of a high-resolution DOA estimation. In a noisy environment, to handle the difficulty in separating signals from noise, we intend to initial beamforming value presets by incoherent eigenvalue in the frequency domain. The high resolution in the frequency domain guarantees the stability of the beamforming. By combining the robustness of conventional beamforming, the proposed method makes use of the subspace deconvolution vector to build a high-resolution beamforming process. The SDV method is aimed to obtain unitary frequency matrixes more stably and improve the accuracy of signal subspaces. The results of simulations and experiments show that when the input SNR is less than -27 dB, signals of decomposition differ unremarkably in the subspace while the SDV method can still obtain clear angles. In a marine background, this method works well in separating the noise and recruiting the characteristics of the signal into the DOA for subsequent processing.
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Wang Y, Li S, Zhang Y, Zhang Z, Yuan S, Wang D. Effect of electric field on coalescence of an oil-in-water emulsion stabilized by surfactant: a molecular dynamics study. RSC Adv 2022; 12:30658-30669. [PMCID: PMC9597590 DOI: 10.1039/d2ra04731d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 10/18/2022] [Indexed: 11/07/2022] Open
Abstract
The microscopic mechanisms of electrocoalescence of O/W emulsions stabilized by surfactant were analyzed from the electric dipole moment of the surfactant, the interaction between surfactant and oil molecules and the deformation of the surfactant.
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Affiliation(s)
- Yudou Wang
- College of Science, China University of Petroleum (East China), Qingdao 266580, China
| | - Shiyan Li
- College of Science, China University of Petroleum (East China), Qingdao 266580, China
| | - Yuanwu Zhang
- College of Science, China University of Petroleum (East China), Qingdao 266580, China
| | - Zhenlei Zhang
- College of Science, China University of Petroleum (East China), Qingdao 266580, China
| | - Shundong Yuan
- College of Science, China University of Petroleum (East China), Qingdao 266580, China
| | - Diansheng Wang
- College of Science, China University of Petroleum (East China), Qingdao 266580, China
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