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Advanced Materials for Energy-Water Systems Center

Research Thrust Area 3: Designing Mesoscale Transport

Thrust Leader: Paul Nealey
Thrust Deputy Leader: Juan de Pablo
Principal Investigators: Seth Darling, Steve Sibener, Dmitri Talapin, Nestor Zaluzec 

Thrust 3 is motivated by three Research Questions:

1. What is the origin of universal, long-range correlations in confined, concentrated nanoparticle solutions in ionic aqueous media at equilibrium?
AMEWS is examining how such correlations affect transport properties (diffusion, viscosity, and normal stress coefficients) through pores. Recent calculations and experiments with simple aqueous solutions suggest that traditional descriptions of water and electrolytes at air/water interfaces are incomplete, and that electrolyte concentration is inhomogeneous at interfaces, with some effects attributed to polarizability. It is unclear how solid/water interfaces, including interfaces with nanoparticles will behave. Traditional descriptions of water in terms of two-body interactions are likely to be incomplete, and an important question is whether three-body effects are necessary to describe water and electrolyte solutions in neutral and charged pores, and in the gaps between charged nanoparticles.

2. Are correlations exacerbated or suppressed by flow and other applied external fields (e.g., voltage) as the system is driven away from equilibrium?
The effect that charged surfaces (or charged nanoparticle surfaces) might have on the range of such correlations in confined, aqueous electrolyte solutions is not known, and experimental reports have started to reveal intriguing behaviors. Conflicting experimental evidence suggests that transport coefficients for the particles and solvent could be significantly enhanced or severely suppressed by surface charges.

3. Can free energy landscapes can be engineered to directly interfere and manipulate ionic correlations in confined aqueous nanoparticle suspensions?
AMEWS seeks to determine whether it is possible to create purposely engineered charge patterns to control article localization, and whether it is possible, through dynamic interference by applied fields, to manipulate the resulting landscapes for applications.

Equipment/ Tools

Electrochemical atomic force microscope (AFM)

  • Figure 1: SECM-AFM component shown on an MFP-3D-BIO AFM.
  • Figure 2: Electrochemistry cell component, shown with a gold standard sample mounted in the cell.
  • Figure 3: SECM probe mount installed on the AFM head.

iCAP PRO X ICP-OES

  • Inductively coupled plasma optical emission spectroscopy (ICP-OES) allows researchers to analyze a solution containing material for specific elements.
  • Typically, this technique can detect a concentration of elements as low as 5 µg/L (ppb) in solution and as much as 100 mg/L (ppm). Almost all metal, transition metal, or metalloid elements that can be dissolved in an acidic solution can be quantified.
  • The system offers easy-to-use software and provides multi-element detection technology. The instrument is ideal for applications with low sample-throughput requirements.

Liquid cell transmission electron microscope 

  • Dynamic measurements of nanoparticle flow under controlled conditions.
  • In-situ elemental spectroscopy facilitates identification of species.

Membrane cross-flow filtration system

  • Bench-scale cross/tangential flow system provides fast and accurate separation performance data of flat sheet membranes.
  • Can mimic either laminar or turbulent flow conditions.
  • Flow conditions (e.g., flow rate, conductivity, temperature) of feed, concentrate and permeate streams are captured and stored in time.    
  • Membranes of varying size and shape can be tested using three membrane testing cells (one acrylic cell and two stainless steel cells). 

Surface zeta potential measurement instrument (SurPASS 3)

  • SurPASS 3 is a high-end electrokinetic analyzer, featuring fully automated zeta potential analysis of macroscopic solids.
  • The tool employs the classic streaming potential and streaming current method for direct analysis of the surface zeta potential.
  • Samples can vary from tiny particles to large wafers (20 mm × 10 mm). High sample throughput (recording of measuring data at >5 Hz, and zeta potential measurement in <2 minutes).
  • Tool provides information on surface charge and related properties and can detect small changes in the outermost material surface.

TOC-L laboratory total organic carbon analyzers

  • Consisting of a PC-controlled model, TOC-L analyzers measures total organic carbon in a wide range of aqueous samples, from ultrapure water to highly contaminated water.
  • A sample with a concentration range of 4 μg/L (ppb) to 30,000 mg/L (ppm) (with the automatic dilution function) can be detected.
  • Equipped with a reliable sample-injection system, which can automatically dilute and reduce sample salinity, acidity, and alkalinity, significantly extending the period of use of catalysts and combustion tubes.
  • Sea water samples can be continuously measured with minimal maintenance.