skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Random Walks and Sticky Surfaces: Single-Molecule Measurements of Solute Diffusion in Ethanol/Water-Filled Anodic Alumina Nanopores

Journal Article · · Journal of Physical Chemistry. C

Nanoporous anodic aluminum oxide (AAO) membranes are now being explored for use in advanced chemical separations, including in the dehydration of biofuels such as ethanol. Optimization of membrane performance requires an in-depth understanding of how solvent mixtures and solutes behave under nanoconfinement. In this work, the diffusion of rhodamine B (RhB) dye through 10 nm and 20 nm AAO nanopores filled with a series of ethanol/water mixtures (0 - 33% water) is explored by fluorescence correlation spectroscopy (FCS). RhB was found to diffuse through the pores by two distinct mechanisms with mean diffusion coefficients, $$D_f$$ and $$D_s$$, reflecting fast and slow diffusive motions, respectively, with values that differ by nearly two orders of magnitude. Further, both $$D_f$$ and $$D_s$$ increased with pore size and were significantly smaller than $$D_b$$, the RhB diffusion coefficient in bulk liquid. Mean $$D_f$$ values follow a composition-dependent trend that closely mimics the viscosity dependence of $$D_b$$. Additional slowing of fast RhB diffusion is attributed to both hydrodynamic drag and electrostatic interactions with the nanopore surface. The mean $$D_s$$ values exhibit a different trend with increasing water content, revealing an increase in $$D_s$$ and a decrease in the contributions of slow diffusion to the observed dynamics. The fluorescence time transient data used in the analysis show that the slow diffusion process is strongly hindered and likely involves frequent adsorption of RhB to the pore surfaces. These results provide new insights into the detailed molecular-level mechanisms of mass transport in nanoporous AAO membranes.

Research Organization:
Kansas State Univ., Manhattan, KS (United States); Argonne National Laboratory (ANL), Argonne, IL (United States). Center for Nanoscale Materials (CNM)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; National Science Foundation (NSF)
Grant/Contract Number:
SC0002362; AC02-06CH11357; CHE-1852182
OSTI ID:
1907562
Journal Information:
Journal of Physical Chemistry. C, Vol. 127, Issue 1; Related Information: https://pubs.acs.org/doi/10.1021/acs.jpcc.2c07083; ISSN 1932-7447
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

References (60)

Nanoconfinement and Mass Transport in Silica Mesopores: the Role of Charge at the Single Molecule and Single Pore Levels journal November 2019
Performance of Fluorescence Correlation Spectroscopy for Measuring Diffusion and Concentration journal November 2005
Three-Dimensional Tracking of Interfacial Hopping Diffusion journal December 2017
Single-Molecule Perspective on Mass Transport in Condensed Water Layers over Gradient Self-Assembled Monolayers journal April 2015
Fluorescence-Correlation Spectroscopy Study of Molecular Transport within Reversed-Phase Chromatographic Particles Compared to Planar Model Surfaces journal November 2014
Spectroscopic and Polarization-Dependent Single-Molecule Tracking Reveal the One-Dimensional Diffusion Pathways in Surfactant-Templated Mesoporous Silica journal December 2015
Diffusion Coefficients of Several Rhodamine Derivatives as Determined by Pulsed Field Gradient–Nuclear Magnetic Resonance and Fluorescence Correlation Spectroscopy journal April 2008
Quantum jumps of single molecules at room temperature journal June 1997
Single Molecule Observations of Desorption-Mediated Diffusion at the Solid-Liquid Interface journal October 2011
Fluorescence Correlation Spectroscopy to Study Diffusion Through Diatom Nanopores journal November 2009
Neutron Scattering Study on Dynamics of Water Molecules in MCM-41 journal July 1999
Confocal microscopy for characterization of porous sol–gel glasses incorporating luminescent dyes journal February 2001
Evidence for confinement induced phase separation in ethanol–water mixture: a positron annihilation study journal December 2017
Fluorescence Imaging of Single-Molecule Retention Trajectories in Reversed-Phase Chromatographic Particles journal September 2013
Molecular diffusion within sol—gel derived matrices viewed via fluorescence recovery after photobleaching journal August 2007
Following Single Molecules to a Better Understanding of Self-Assembled One-Dimensional Nanostructures journal September 2013
Morphological zeta-potential variation of nanoporous anodic alumina layers and cell adherence journal February 2014
Entrapment of Individual DNA Molecules and Nanoparticles in Porous Alumina Membranes journal December 2009
Solvation Dynamics and Proton Transfer in Nanoconfined Liquids journal May 2011
Investigating axial diffusion in cylindrical pores using confocal single-particle fluorescence correlation spectroscopy journal June 2016
Commercial counterboard for 10 ns software correlator for photon and fluorescence correlation spectroscopy journal November 2016
Self-diffusion of heptane inside aggregates of porous alumina particles by pulsed field gradient NMR journal July 2016
Orientational Dynamics of Liquids Confined in Nanoporous Sol−Gel Glasses Studied by Optical Kerr Effect Spectroscopy journal August 2003
Art and Artefacts of Fluorescence Correlation Spectroscopy journal April 2004
Controllable Reduction of Anionic Contamination in Degradable Amorphous Anodic Alumina Nanoporous Membranes journal October 2020
Potentiometric Response Characteristics of Oxide-Coated Gallium Electrodes in Aqueous Solutions journal October 2014
Dye Diffusion at Surfaces: Charge Matters journal February 2010
Molecular diffusivity measurement through an alumina membrane using time-resolved fluorescence imaging journal November 2010
Direct Observation of Wetting and Diffusion in the Hydrophobic Interior of Silica Nanotubes journal January 2004
Adsorption and Diffusion of Single Molecules at Chromatographic Interfaces journal July 2003
Neutron Scattering Study on Dynamics of Water Molecules in MCM-41. 2. Determination of Translational Diffusion Coefficient journal June 2005
Single-Molecule Investigations of Morphology and Mass Transport Dynamics in Nanostructured Materials journal July 2015
Intrinsic property measurement of surfactant-templated mesoporous silica films using time-resolved single-molecule imaging journal April 2008
Spectroscopic study of fluorescein immobilized on anodic porous alumina in aqueous solutions of different pH journal February 2020
Heterogeneous Single-Molecule Diffusion in One-, Two-, and Three-Dimensional Microporous Coordination Polymers: Directional, Trapped, and Immobile Guests journal May 2012
Liquid-phase Adsorption of Bulk Ethanol–Water Mixtures by Alumina journal March 1993
Confined Diffusion in Ordered Nanoporous Alumina Membranes journal March 2007
Study of hydrogen bonding in ethanol-water binary solutions by Raman spectroscopy journal January 2018
Fluorescence correlation spectroscopy. I. Conceptual basis and theory journal January 1974
Porous Anodic Aluminum Oxide: Anodization and Templated Synthesis of Functional Nanostructures journal June 2014
Probing Strong Adsorption of Solute onto C18-Silica Gel by Fluorescence Correlation Imaging and Single-Molecule Spectroscopy under RPLC Conditions journal March 2005
Preferential Adsorption from Liquid Water–Ethanol Mixtures in Alumina Pores journal June 2014
Nanoporous anodic aluminium oxide: Advances in surface engineering and emerging applications journal June 2013
Fluorescence Recovery after Photobleaching and Single-Molecule Tracking Measurements of Anisotropic Diffusion within Identical Regions of a Cylinder-Forming Diblock Copolymer Film journal May 2015
Molecular Length Dependence of Single Molecule Wobbling within Surfactant- and Solvent-Filled Silica Mesopores journal July 2013
Direct Observation of Transitions between Surface-Dominated and Bulk Diffusion Regimes in Nanochannels journal July 2009
Phase separation of acetonitrile-water mixtures and minimizing of ice crystallites from there in confinement of MCM-41 journal March 2007
Reporters in the nanoworld: diffusion of single molecules in mesoporous materials journal January 2010
Electrophoretic Migration and Axial Diffusion of Individual Nanoparticles in Cylindrical Nanopores journal August 2012
Fluorescence correlation spectroscopy of triplet states in solution: a theoretical and experimental study journal September 1995
Microscopic Movement of Slow-Diffusing Nanoparticles in Cylindrical Nanopores Studied with Three-Dimensional Tracking journal April 2016
Single molecule fluorescence imaging of nanoconfinement in porous materials journal January 2021
Successful FCS Experiment in Nonstandard Conditions journal July 2014
Single-Molecule Probing of Mixed-Mode Adsorption at a Chromatographic Interface journal December 1998
Microscopic Structure and Mobility of Guest Molecules in Mesoporous Hybrid Organosilica: Evaluation with Single-Molecule Tracking journal May 2009
Electrostatic properties of inner nanopore surfaces of anodic aluminum oxide membranes upon high temperature annealing revealed by EPR of pH-sensitive spin probes and labels journal June 2020
Effects of confinement on freezing and melting journal January 2006
Intermittent Molecular Hopping at the Solid-Liquid Interface journal June 2013
Raman Spectroscopy of Water–Ethanol Solutions: The Estimation of Hydrogen Bonding Energy and the Appearance of Clathrate-like Structures in Solutions journal October 2015
Numerical Fluorescence Correlation Spectroscopy for the Analysis of Molecular Dynamics under Nonstandard Conditions journal April 2007