ORCID Profile
0000-0002-9759-4102
Current Organisations
Chongqing University
,
The University of Queensland School of Chemical Engineering
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Publisher: American Chemical Society (ACS)
Date: 11-09-2018
Abstract: We have used nonequilibrium molecular dynamics simulations to investigate the transport diffusion of methane, at 300 K and pressures of up to 15 bar, in 30 nm-long (10, 10) carbon nanotubes (CNTs) held between two flanges mounted at the ends to represent the surface layers of an embedding matrix material. Strong interfacial resistance to the entry and exit of molecules is found in the 30 nm-long CNTs, which reduces their permeability by more than 2 orders of magnitude. Increasing the adsorption affinity and surface area of the flange reduces the interfacial resistance and consequently enhances the methane diffusivity in CNT membranes. Curved streamlines near the flange surface make a significant contribution to the permeability, even when the adsorption on the matrix surface is negligible. We propose a model to calculate the separate components of the interfacial resistance, the flange resistance, which increases with increase in the membrane porosity, and the entrance-exit resistance, which is independent of the membrane porosity. While the flange resistance accounts for the reduction of interfacial resistance with decrease in the membrane porosity, the entrance-exit resistance is responsible for the reduction of interfacial resistance with increase in the flange adsorption affinity. The flange resistivity demonstrates a complex dependency on the flange adsorption affinity, which is attributed to the competition between the enhanced adsorption and the enhanced migration time of the molecules on the flange. It is concluded that the embedding matrix adsorption affinity and membrane porosity separately play critical roles in determining the interfacial resistance and permeability in CNT membranes. Our simulation results can help reduce the interfacial resistance and improve the permeance in CNT membranes by appropriate choice of intertube spacing and flange material and are readily applied to all nanoporous membranes with a passive matrix.
Publisher: Elsevier BV
Date: 05-2019
Publisher: Elsevier BV
Date: 2023
Publisher: American Chemical Society (ACS)
Date: 05-08-2019
Publisher: American Chemical Society (ACS)
Date: 20-06-2013
DOI: 10.1021/JP403477Y
Publisher: MDPI AG
Date: 29-11-2022
DOI: 10.3390/MOLECULES27238340
Abstract: Supercritical carbon dioxide (sCO2) has great potential for displacing shale oil as a result of its high solubility and low surface tension and viscosity, but the underlying mechanisms have remained unclear up to now. By conducting equilibrium molecular dynamics (EMD) simulations, we found that the displacing process could be ided into three steps: the CO2 molecules were firstly injected in the central region of shale slit, then tended to adsorb on the SiO2-OH wall surface and mix with hexane, resulting in loose hexane layer on the shale surface, and finally displaced hexane from the wall due to strong interactions between CO2 and wall. In that process, the displacing velocity and efficiency of hexane exhibit parabolic and increased trends with pressure, respectively. To gain deep insights into this phenomenon, we further performed non-equilibrium molecular dynamics (NEMD) simulations and found that both the Onsager coefficients of CO2 and hexane were correlated to increase with pressure, until the diffusion rate of hexane being suppressed by the highly dense distribution of CO2 molecules at 12 MPa. The rapid transportation of CO2 molecules in the binary components (CO2 and hexane) actually promoted the hexane diffusion, which facilitated hexane flowing out of the nanochannel and subsequently enhanced oil recovery efficiency. The displacing process could occur effectively at pressures higher than 7.5 MPa, after which the interaction energies of the CO2-wall were stronger than that of the hexane-wall. Taking displacing velocity and efficiency and hexane diffusion rate into consideration, the optimal injection pressure was found at 10.5 MPa in this work. This study provides detailed insights into CO2 displacing shale oil and is in favor of deepening the understanding of shale oil exploitation and utilization.
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 11-2022
Publisher: American Chemical Society (ACS)
Date: 15-11-2016
Publisher: Elsevier BV
Date: 06-2019
Publisher: American Chemical Society (ACS)
Date: 15-06-2017
DOI: 10.1021/ACS.LANGMUIR.7B01070
Abstract: We investigate the transport diffusion of methane at 300 K and pressures of up to 15 bar in dry and wetted carbon nanotubes (CNTs) having diameters ranging from 0.95 to 2.034 nm using nonequilibrium molecular dynamics (NEMD) simulation. Because of their strong hydrogen bonding, preadsorbed water molecules transport in the form of clusters and block the diffusion of methane, reducing the Onsager coefficient of methane dramatically compared to that in dry CNTs. The reduction in the methane Onsager coefficient is greater in narrower CNTs or at higher water densities. Because the diameter of the water clusters is almost invariant with water density, the Onsager coefficient of water in the (10, 10) CNT increases linearly with water density. It is further found that whereas decreasing the CNT diameter from 2.034 to 0.95 nm enhances the Onsager coefficient of pure methane by about 1 order of magnitude, the Onsager coefficient of water is almost independent of the CNT diameter at a water density of 0.05 g/cm
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 2019
Publisher: American Chemical Society (ACS)
Date: 10-04-2020
Publisher: Hindawi Limited
Date: 08-2021
DOI: 10.1002/ER.7008
Publisher: American Chemical Society (ACS)
Date: 14-01-2021
Publisher: MDPI AG
Date: 08-07-2018
DOI: 10.3390/MA11071164
Publisher: Elsevier BV
Date: 08-2021
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 12-2017
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 09-2020
Publisher: MDPI AG
Date: 29-01-2022
DOI: 10.3390/MEMBRANES12020164
Abstract: The fouling/wetting of hydrophobic membrane caused by organic substances with low-surface energy substantially limits the development of the membrane distillation (MD) process. The sulfate radical (SO4 ·−)-based advanced oxidation process (AOP) has been a promising technology to degrade organics in wastewater treatment, and peroxydisulfate (PDS) could be efficiently activated by heat. Thus, a hybrid process of MD-AOP via PDS activated by a hot feed was hypothesized to mitigate membrane fouling/wetting. Experiments dealing with sodium dodecyl sulfate (SDS) containing a salty solution via two commercial membranes (PVDF and PTFE) were performed, and varying membrane wetting extents in the coupling process were discussed at different PDS concentrations and feed temperatures. Our results demonstrated permeate flux decline and a rise in conductivity due to membrane wetting by SDS, which was efficiently alleviated in the hybrid process rather than the standalone MD process. Moreover, such a mitigation was enhanced by a higher PDS concentration up to 5 mM and higher feed temperature. In addition, qualitative characterization on membrane coupons wetted by SDS was successfully performed using electrochemical impedance spectroscopy (EIS). The EIS results implied both types of hydrophobic membranes were protected from losing their hydrophobicity in the presence of PDS activation, agreeing with our initial hypothesis. This work could provide insight into future fouling/wetting control strategies for hydrophobic membranes and facilitate the development of an MD process.
Publisher: Elsevier BV
Date: 07-2021
Publisher: American Chemical Society (ACS)
Date: 23-12-2014
DOI: 10.1021/JP5099987
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 08-2023
Publisher: American Chemical Society (ACS)
Date: 15-04-2021
Publisher: Elsevier BV
Date: 06-2023
Publisher: Elsevier BV
Date: 12-2021
Location: Australia
No related grants have been discovered for Lang Liu.