Selective Removal of Ions from Aqueous Solutions

Patrick Campbell | 18-ERD-024

Project Overview

The low-cost, selective removal of ions from dilute aqueous mixtures is a grand challenge in separation science. Lawrence Livermore National Laboratory's capacitive deionization (CDI) platform is ideal for efficiently removing ions from low-salinity water and has demonstrated selective removal. The goal of this project was to elucidate the fundamental mechanisms of selectivity in CDI and optimize performance and selectivity for various toxic, troublesome, or valuable ions of interest.

Our approach combined experiment and theory, harnessing our decade-plus of CDI device development experience and Livermore's unparalleled supercomputing capabilities. We investigated how specific ion properties, such as geometry, hydration energy, and polarizability, interact with the unique and tunable pore structure of the carbon aerogel electrodes used in our CDI platform. Advanced dynamics simulations provided insight into ion exchange kinetics and voltage-dependent selectivity phenomena.

Ultimately, we were able to achieve record selectivity for nitrate ions in the presence of both mono- and divalent interferant ions. We also demonstrated switchable selectivity for hardness-forming calcium ions, and we developed the most advanced, integrated multiscale/multiphysics model of CDI device operation available in the scientific community.

Mission Impact

This project directly supported the Laboratory's energy security and climate resilience mission focus area, with an emphasis on Livermore's core competencies in high-performance computing, simulation, and data science and advanced materials and manufacturing.

Publications, Presentations, and Patents

Aydin, F., et al. 2020. “Selectivity of Nitrate and Chloride Ions in Microporous Carbons: the Role of Anisotropic Hydration and Applied Potentials.” Nanoscale. doi:10.1039/D0NR04496B. LLNL-JRNL-811539

Ceron, M. 2019. "Carbon Aerogels for Electrical Energy Storage and Water Desalination." The Southeastern Regional Meeting of the American Chemical Society, October 2019. LLNL-PRES-793822

——— 2020. “Cation Selectivity in Capacitive Deionization: Elucidating the Role of Pore Size, Electrode Potential, and Ion Dehydration.” ACS Applied Materials & Interfaces 12 (38): 42644–52. LLNL-JRNL-809022

Campbell, P. 2019a. “Enhanced and Tunable Ion Selectivity in Flow-Through Electrode Capacitive Deionization with Advanced Carbon Aerogel Electrodes.” Materials Research Society, April 2019. LLNL-ABS-760441

——— 2019b. “Selective Ion Removal Using Flow-Through Electrode Capacitive Deionization.” 4th International Conference of Capacitive Deionization and Electrosorption, May 2019. LLNL-ABS-763242

——— 2020a. "Energy transfer for storage or recovery in capacitive deionization using a DC-DC converter." J. Power Sources. 448. doi:10.1016/j.jpowsour2019.227409. LLNL-JRNL-811081

——— 2020b. "Structural Anomalies and Electronic Properties of an Ionic Liquid under Nanoscale Confinement." J. Phys. Chem. Lett.,11. 6150-6155. LLNL-JRNL-809619

Campbell, P., et al. 2019. “System and method for using ultramicroporous carbon for the selective removal of nitrate with capacitive deionization.” U.S. Patent Application No. 16/268154, U.S. Patent Application Publication No. US2020/0247693 A1.

Campbell, P., et al. 2020. “Selective removal of scale-forming ions for water softening using flow through electrode capacitive deionization with carbon aerogel electrodes having optimal pore size distribution.” U.S. Patent Application No. 16/929,445.

Hawks, S., et al. 2019a. "Performance metrics for the objective assessment of capacitive deionization systems." Water Res,152. 126-137. LLNL-JRNL-749416

——— 2019b. “Using Ultramicroporous Carbon for the Selective Removal of Nitrate with Capacitive Deionization.” Environmental Science & Technology 53, 10863–70. LLNL-JRNL-768579

——— 2020. “System and method for high efficiency electrochemical desalination.” Issued U.S. Patent 10,875,792 B2.

Kuo, H., et al. 2020. “Understanding Resistances in Capacitive Deionization Devices.” Environmental Science-Water Research & Technology 6, 1842–54. LLNL-JRNL-805361

Ramachandran, A., et al. 2019. "Comments on Comparison of energy consumption in desalination by capacitive deionization and reverse osmosis.” Desalination 461, 30-36. LLNL-JRNL-770722

Zhan, C. 2019. “Interplay between Specific-Ion Effects and Confinement in the Aqueous Electrochemical Interface.” ACS Fall Meeting, San Diego, CA, August 2019. LLNL-PRES-788000

Zhan, C., et al. 2019. “Specific Ion Effects at Graphitic Interfaces.” Nature Communications, 10. doi:10.1038/s41467-019-12854-7. LLNL-JRNL-778780