(6jb) Rational Design of Nanofiltration Membranes for the Removal of Trace Organic Contaminants from Waste Water Based on Single-Molecule Dynamics and Heterogeneity

Research Interests:

Research Experience

A common theme in my current and planned research is the rational design of emerging technologies based on a mechanistic understanding of their deficiencies. This approach has been specifically applied to the development of immobilized enzyme sensor for the detection of explosive chemicals. Enzyme sensor technology has incredible potential, but limited success due to the loss of enzyme function upon immobilization. Significant advances in understanding of the mechanism behind the reduced activity of immobilized enzymes has been possible through several complementary single-molecule fluorescence microscopy techniques in combination with sophisticated trajectory analysis using stochastic (non)linear state-space models. Using these methods, we have been able to quantitatively identify heterogeneity in functionality of immobilized enzymes and distinguish several important modes of failure, including inaccessible active sites, structural instability, inhibited conformational mobility, and substrate/product transport barriers, which are typically convoluted by less sophisticated measurements and analyses. Using this nuanced understanding of immobilized enzyme function, we developed several immobilization materials and methods showing enhanced performance relative to enzymes in solution.

Research Plan

As a faculty member, I will employ the same strategy and suite of techniques to address several challenges related to the removal of trace organic contaminants (TOCs), such as active pharmaceutical ingredients, organic dyes, and byproduct of chemical manufacturing, from municipal and industrial waste water via nonporous or nanoporous nanofiltration (NF) membranes. Conventional aqueous NF technology generally has low TOC rejection efficiency < 50%. Moreover, NF membranes in general are constrained by the trade-off between permeability and selectivity, which complicates optimization. To overcome this constraint, modifications to membrane materials are often made by generating pores in the membrane, incorporating porous materials, or functionalizing for selective chemical affinity; however the resulting membranes often underperform owing to the lack of a detailed description of the transport of solutes into and within the membranes, which is undoubtedly mirrors the complexity and heterogeneity of the membrane material. Current methods for assessing the membrane properties are reliant on ensemble mass transport, and microscopy based structural characterization, yielding limited mechanistic insight and ambiguity in the steps for improvement.

The single molecule tracking and non-Markovian machine learning trajectory analysis developed during my postdoc enabled the detection of 3D single-molecule diffusion in dense polymer materials with unprecedented resolution. By tracking the penetration and diffusion of many individual organic solute molecules (typically ~10⁵ molecular trajectories) in NF membranes, my research will capture detailed information as to the properties that can be used to control solute adsorption, penetration, internal transport, and rejection. This will provide the feedback necessary for rationally designed modifications that will yield step-changes in nanofiltration membrane performance. The studied membrane materials and modifications will be accomplished through a combination of in-house synthesis, industrial partnerships, and academic research collaborations. If successful, these tactics will also be applied to multi-solute systems, and organic solvent nanofiltration for the purpose of optimizing solute fractionation, which is an important step in purifying chemical and pharmaceutical products.

Another critical challenge associated with NF membrane technology for water treatment is fouling by biomolecules, which reduces the effective life of the membrane. This challenge is typically addressed using surface modification with non-fouling chemicals such as hydrophilic polymer brushes. While these can significantly reduce the rate of fouling, success often occurs at the cost of permeability or selectivity. I plan to apply the methods I’ve developed to detect heterogeneity in single molecule conformational dynamics, adsorption, and surface diffusion of FRET labeled biomolecules on the surface of NF membrane materials. A detailed understanding of the fouling process at the molecular level, and the potential role of surface heterogeneity, as well as the changes to the small molecule transport is necessary to determine how fouling and performance can be mutually controlled. I plan to use this information to develop materials, and membrane modification strategies that will balance the reduced rate of fouling with retained membrane permeability and selectivity.

Teaching Interests:

While I am open to teaching any chemical engineering class, I have several preferences consistent with my strengths and experience. Specifically, I think that I could be an effective teacher for a computational and numerical methods course, as I have been a TA for a course in this subject area. I would also be interested in teaching transport phenomena or thermodynamics at the undergraduate or graduate level. Finally, I would like to offer an elective focused on interfacial phenomena, which is relate to my general field of research.

Publications

1. Weltz, J. S.; Kienle, D. F.; Schwartz, D. K.; Kaar, J. L. Dramatic Increase in Catalytic Performance of Immobilized Lipases by Their Stabilization on Polymer Brush Supports. ACS Catal. 2019, 4992–5001.
2. Bull, D. S.; Kienle, D. F.; Chaparro Sosa, A. F.; Nelson, N.; Shambojit, R.; Cha, J. N.; Schwartz, D. K.; Kaar, J. L.; Goodwin, A. P. Surface-Templated Nanobubbles Protect Proteins from Surface-Mediated Denaturation, Phys. Chem. Lett., 2019, 10 (11), 2641-2647
3. Morrin, G. T.; Kienle, D. F.; Schwartz, D. K., Standalone Interferometry-Based Calibration of Convex Lens-Induced Confinement Microscopy with Nanoscale Accuracy. Analyst 2019, In-Press.
4. Kienle, D. F.; Schwartz, D. K. Complex Salt Dependence of Polymer Diffusion in Polyelectrolyte Multilayers. Phys. Chem. Lett.,2019, 10 (5), pp 987–992
5. Kienle, D. F.; Falatach, R. M.; Kaar, J. L.; Schwartz, D. K., Correlating Structural and Functional Heterogeneity of Immobilized Enzymes. ACS Nano 2018, 12, 8091-8103.
6. Chaparro Sosa, A. F.; Kienle, D. F.; Falatach, R. M.; Flanagan, J.; Kaar, J. L.; Schwartz, D. K., Stabilization of Immobilized Enzymes via the Chaperone-Like Activity of Mixed Lipid Bilayers. ACS Appl. Mater. Interfaces 2018, 10, 19504-19513.
7. Marruecos, D. F.; Kienle, D. F.; Kaar, J. L.; Schwartz, D. K., Grafting Density Impacts Local Nanoscale Hydrophobicity in Poly(Ethylene Glycol) Brushes. ACS Macro Letters 2018, 7, 498-503.
8. *Kienle, D. F.; de Souza, J. V.; Kuhl, T. L., Large-Area Release and Transfer of Ultrathin, Freestanding Nanocrystalline Ceria Films. Thin Solid Films 2017, 638, 318-323.
9. *Kienle, D. F.; Kuhl, T. L., Analyzing Refractive Index Profiles of Confined Fluids by Interferometry Part II: Multilayer and Asymmetric Systems. Chim. Acta 2016, 936, 236-244.
10. Kienle, D. F.; Kuhl, T. L., Density and Phase State of a Confined Nonpolar Fluid. Rev. Lett. 2016, 117.
11. Kienle, D. F.; Kuhl, T. L., Analyzing Refractive Index Profiles of Confined Fluids by Interferometry. Chem. 2014, 86, 11860-11867.
12. Kienle, D. F.; de Souza, J. V.; Watkins, E. B.; Kuhl, T. L., Thickness and Refractive Index of Dppc and Dppe Monolayers by Multiple-Beam Interferometry. Bioanal. Chem. 2014, 406, 4725-4733.
13. Hardisty, M. R.; Kienle, D. F.; Kuhl, T. L.; Stover, S. M.; Fyhrie, D. P., Strain-Induced Optical Changes in Demineralized Bone. Biomed. Opt. 2014, 19.

*Corresponding Authorships