2D Ti3C2Tx MXene nanosheets coated cellulose fibers based 3D nanostructures for efficient water desalination

Capacitive deionization (CDI) is a newly developed desalination technology with low energy consumption and environmental friendliness. The surface area restricts the desalination capacities of traditional carbon-based CDI electrodes while battery materials emerge as CDI electrodes with high performances due to the larger electrochemical capacities, but suffer limited production of materials. LiMn2O4 is a massively-produced lithium-ion battery material with a stable spinel structure and a high theoretical specific capacity of 148 mAh·g-1, revealing a promising candidate for CDI electrode. Herein, we employed spinel LiMn2O4 as the cathode and activated carbon as the anode in the CDI cell with an anion exchange membrane to limit the movement of cations, thus, the lithium ions released from LiMn2O4 would attract the chloride ions and trigger the desalination process of the other side of the membrane. An ultrahigh deionization capacity of 159.49 mg·g-1 was obtained at 1.0 V with an initial salinity of 20 mM. The desalination capacity of the CDI cell at 1.0 V with 10 mM initial NaCl concentration was 91.04 mg·g-1, higher than that of the system with only carbon electrodes with and without the ion exchange membrane (39.88 mg·g-1 and 7.84 mg·g-1, respectively). In addition, the desalination results and mechanisms were further verified with the simulation of COMSOL Multiphysics.

Ti3C2Tx MXene@carbon dots hybrid microflowers as a binder-free electrode material toward high capacity capacitive deionization

Insights on features' contribution to desalination dynamics and capacity of capacitive deionization through machine learning study

The world is suffering from chronic water shortage due to the increasing population, water pollution and industrialization. Desalinating saline water offers a rational choice to produce fresh water thus resolving the crisis. Among various kinds of desalination technologies, capacitive deionization (CDI) is of significant potential owing to the facile process, low energy consumption, mild working conditions, easy regeneration, low cost and the absence of secondary pollution. The electrode material is an essential component for desalination performance. The most used electrode material is carbon-based material, which suffers from low desalination capacity (under 15 mg·g−1). However, the desalination of saline water with the CDI method is usually the charging process of a battery or supercapacitor. The electrochemical capacity of battery electrode material is relatively high because of the larger scale of charge transfer due to the redox reaction, thus leading to a larger desalination capacity in the CDI system. A variety of battery materials have been developed due to the urgent demand for energy storage, which increases the choices of CDI electrode materials largely. Sodium-ion battery materials, lithium-ion battery materials, chloride-ion battery materials, conducting polymers, radical polymers, and flow battery electrode materials have appeared in the literature of CDI research, many of which enhanced the deionization performances of CDI, revealing a bright future of integrating battery materials with CDI technology.

Mesopore-dominated porous carbon derived from confinement-region activation strategy toward high capacitive desalination performance

Predicting the salt adsorption capacity of different capacitive deionization electrodes using random forest

Flexible self-supporting CoFe-LDH/MXene film as a chloride ions storage electrode in capacitive deionization

Nowadays, capacitive deionization (CDI) has emerged as a prominent technology in the desalination field, typically utilizing porous carbons as electrodes. However, the precise significance of electrode properties and operational conditions in shaping desalination performance remains blurry, necessitating numerous time-consuming and resource-intensive CDI experiments. Machine learning (ML) presents an emerging solution, offering the prospect of predicting CDI performance with minimal investment in electrode material synthesis and testing. Herein, four ML models are used for predicting the CDI performance of porous carbons. Among them, the gradient boosting model delivers the best performance on test set with low root mean square error values of 2.13mg g-1 and 0.073mg g-1 min-1 for predicting desalination capacity and rate, respectively. Furthermore, SHapley Additive exPlanations is introduced to analyze the significance of electrode properties and operational conditions. It highlights that electrolyte concentration and specific surface area exert a substantially more influential role in determining desalination performance compared to other features. Ultimately, experimental validation employing metal-organic frameworks-derived porous carbons and biomass-derived porous carbons as CDI electrodes is conducted to affirm the prediction accuracy of ML models. This study pioneers ML techniques for predicting CDI performance, offering a compelling strategy for advancing CDI technology.

The availability of clean and safe water is still a big challenge in most parts of the world. Drinking water should be free of harmful microorganisms and should contain the required amount of minerals based on the set standards. In this study, silver nanoparticles (Ag-n) embedded in Activated Carbon (AC) electrodes for capacitive deionization (CDI) were evaluated for desalination and also for anti-microbial activities against Escherichia coli and Salmonella enteritidis. The novel AC/Ag-n electrodes were prepared by mixing Activated Carbon powder together with silver nanoparticles. The morphology, surface functional groups, and porosity were characterized by Scanning Electron Microscope (SEM), Fouriertransform infrared (FT-IR), and nitrogen adsorption studies which affirm the formation of disinfecting electrode material. The desalination and disinfection performance of the fabricated electrodes were evaluated by Capacitive Deionization batch mode experiment using natural water collected from the Nganana stream while applying the potential of 2 V for 3h. The AC/Ag-n Capacitive Deionization (CDI) electrodes achieved 100% Escherichia coli and 98% Salmonella enteritidis removal and 45% salt removal efficiency, and electrosorption capacity of 2.56 mg/g and the ions removal efficiency of 89%, 40%, 2.4%, 57.9%, 50%, 8% and 33% for Na+ , K+ , Ca2+ , Mg2+ , PO4 3- , NO3 - and Clrespectively. The microbial disinfection mechanisms were through electrosorption process and physical contacts with the embedded Ag-n. Thus, it is possible to disinfect the water while also removing salt simultaneously using Capacitive Deionization. Therefore, AC/Ag-n are considered as novel electrode material with an excellent antimicrobial agent for the Capacitive Deionization process. URI

Exploring MXene’s role in capacitive deionization: Advances, challenges, and future directions

Capacitive deionization (CDI) is a low energy desalination technology with long-cycle life, which utilizes high-porosity capacitive electrodes for capturing ions from flowing saline water [1, 2]. Though still suffering from relatively low desalination capacity, one major advantage of CDI technology is its low energy requirement and high rate operation for desalination. In recent years, much effort has been put on improving electrode materials for CDI applications. These studies have mostly focused either on the use of novel electrode materials or on surface modifications (e.g. metal oxide growth, chemical treatment, and thermal treatment) of the existing CDI electrode materials [1, 3, 4]. Although thermal treatment of carbon electrodes for improved charge storage is a well-established approach, the effects of various thermal treatment procedures on the performance of CDI electrodes still remain unexplored. Inherent similarities between the operating principles of supercapacitors and CDI technology might make one to think a similar correlation could be established between thermal treatment and the CDI performance. However, due to major differences in required charge storage mechanisms, a detailed study on various treatment conditions should be conducted to understand which conditions specifically promote better ion adsorption in CDI electrodes. Motivated by this, the effects of different thermal treatment conditions (i.e., temperature and gases) on salt adsorption performances of the activated carbon cloth (ACC) electrodes were investigated. Major discrepancy between stored charge versus salt adsorption capacity (SAC) was observed for different treatment conditions. To better assess these effects, additional BET and Raman tests on the ACC electrodes were also conducted. Results indicated interesting observations regarding charge storage capacity and SAC for different treatment conditions, which highlights the importance of selecting a suitable thermal treatment condition for enhancing the CDI performance of ACC electrodes.

Even though two-thirds of our world's surface is covered by water, less than 1% of that water can be directly consumed to satisfy the rapid growth in population, urbanization, and industrialization.[1] Water quality and scarcity have become some of the most important global challenges of our time. Current desalination technologies such as multi-stage flash distillation and reverse osmosis can be costly to implement and operate, requiring significant pretreatment and consistent maintenance procedures.[2] Thus, investigations into alternative desalination options are being explored toward building more sustainable water treatment systems.Capacitive deionization (CDI) is a desalination technology using highly porous carbon electrodes that can reversibly adsorb dissolved ions. By regulating applied voltages to a CDI cell, ionized salts are trapped in the electric double layers (EDLs) at carbon electrodes, thereafter desalinating water in the CDI cell.[3] CDI technology may have potential advantages over current desalination methods in that no heat treatment or high pressure is required, potentially leading to a significant decrease in the operational and energy costs compared to current desalination processes and aiding in the production of clean/fresh water.Since 2011, researchers from the University of Kentucky Center for Applied Energy Research (UK CAER) have contributed to ongoing efforts to advance CDI technology from theoretical studies to applied process research.[3-22] Works primarily include the improvement of desalination capacity, mitigation of performance degradation, and technology commercialization. In this talk, one of the presenters will provide key milestones of the CDI technology developed at UK CAER in honor of Prof. D. Noel Buckley for his 50-year experience in electrochemistry research.Ref:[1] M. Elimelech, W.A. Phillip, The future of seawater desalination: energy, technology, and the environment, Science, 333 (6043) (2011), pp. 712-717[2] J.-J. Yan, S.-F. Shao, J.-H. Wang, J.-P. Liu, Improvement of a multi-stage flash seawater desalination system for cogeneration power plants, Desalination, 217 (1) (2007), pp. 191-202[3] A. Omosebi, X. Gao, J. Rentschler, J. Landon, K.-K. Liu, Continuous operation of membrane capacitive deionization cells assembled with dissimilar potential of zero charge electrode pairs, J. Colloid Interf. Sci., 446 (2015), pp. 345-351[4] J. Landon, X. Gao, A. Omosebi, K. Liu, “Local pH Effects on Carbon Oxidation in Capacitive Deionization Architectures” Environmental Science: Water Research & Technology, 7, 861 – 869 (2021)[5] A. Omosebi, Z. Li, N. Holubowitch, X. Gao, J. Landon, A. Cramer, K. Liu, “Energy recovery in capacitive deionization systems with inverted operation characteristics”, Environmental Science: Water Research & Technology, 6, 321-330 (2020)[6] X. Gao, A. Omosebi, Z. Ma, F. Zhu, J. Landon, M. Ghorbanian, N. Kern, K. Liu, “Capacitive Deionization Using Symmetric Carbon Electrode Pairs”, Enviro. Sci.: Water Res. Tech., 5, 660-671 (2019).[7] J. Landon, X. Gao, A. Omosebi, K. Liu, “Progress and outlook for capacitive deionization technology”, Current Opinion in Chemical Engineering, 25, 1-8 (2019)[8] N. Holubowitch, A. Omosebi, X. Gao, J. Landon, K. Liu, “Membrane-Free Electrochemical Deoxygenation of Aqueous Solutions Using Symmetric Activated Carbon Electrodes in Flow-Through Cells”, Electrochim. Acta., 297, 163-172 (2019).[9] X. Gao, A. Omosebi, J. Landon, K. Liu, “Voltage-Based Stabilization of Microporous Carbon Electrodes for Inverted Capacitive Deionization”, J. Phys. Chem. C, 122, 1158-1168 (2018).[10] A. Omosebi, X. Gao, N. Holubowitch, Z. Li, J. Landon, K. Liu, “Anion Exchange Membrane Capacitive Deionization Cells”, J. Electrochem. Soc., 164, E242-E247 (2017).[11] N. Holubowitch, A. Omosebi, X. Gao, J. Landon, K. Liu, “Quasi-Steady-State Polarization Reveals the Interplay of Capacitive fand Faradaic Process in Capacitive Deionization”, ChemElectroChem, 4, 2404-2413 (2017).[12] X. Gao, A. Omosebi, N. Holubowitch, J. Landon, K. Liu, “Capacitive Deionization Using Alternating Polarization: Effect of Surface Charge on Salt Removal”, Electrochim. Acta, 233, 249-255 (2017).[13] X. Gao, A. Omosebi, N. Holubowitch, A. Liu, K. Ruh, J. Landon, K. Liu, “Polymer-Coated Composite Anodes for Efficient and Stable Capacitive Deionization”, Desalination, 399, 16-20 (2016).[14] X. Gao, S. Porada, A. Omosebi, K. Liu, P. M. Biesheuvel, J. Landon, “Complementary Surface Charge for Enhanced Capacitive Deionization”, Water Res., 92, 275-282 (2016).[15] X. Gao, A. Omosebi, J. Landon, K. Liu, “Enhanced Salt Removal in an Inverted Capacitive Deionization Cell Using Amine Modified Microporous Carbon Electrode”, Environ. Sci. Tech., 49, 10920 (2015).[16] X. Gao, A. Omosebi, J. Landon, K. Liu, “Surface Charge Enhanced Carbon Electrodes for Stable and Efficient Capacitive Deionization Using Inverted Adsorption-Desorption Behavior”, Energy Environ. Sci., 8, 897 (2015)[17] X. Gao, A. Omosebi, J. Landon, K. Liu, “Dependence of the Capacitive Deionization Performance of Potential of Zero Charge Shifting of Carbon Xerogel Electrodes during Long-Term Operation”, J. Electrochem. Soc., 161, E159 (2014).

Co-Co3O4 encapsulated in nitrogen-doped carbon nanotubes for capacitive desalination: Effects of nano-confinement and cobalt speciation

A study of the effect of carbon characteristics on capacitive deionization (CDI) performance

Recent advanced freestanding pseudocapacitive electrodes for efficient capacitive deionization