CDI

Many times when I passed by the conference venue of our 2019 CDI&E conference, it reminds me of the wonderful days we were together to share our passion and knowledge towards better understanding and application of CDI-related technologies. Those CDI&E conferences held every other year have been great opportunities for all top researchers and engineers in this field to meet and communicate in person. However, due to the attack of COVID-19 which greatly affects the ways of our living and working, organizers of 2021 conference have decided to move it online. I believe it will be a great opportunity for us to meet and share again.
Despite those changes, CDI research is not at a standstill at all. Up to 380 papers have been published in Web of Science indexed journals in the year 2020, 50 papers more than last year. With considerable difficulties to perform experimental studies, many research groups have been making great efforts on reviewing works and published them in top journals.
These remarkable contributions allow CDI to retain its hot-topic status in the field of environmental science and technology through this year, which also gives all communities great happiness and confidence to pursue our research. I would like to wish you a happy and fruitful new year. And again,

I look forward to seeing you all at CDI&E 2021 conference.
- Prof. Dr.Peng Liang,
   Chairman - CDI&E working group.

We are less than four months away from the next CDI&E conference, to be held from May 11 onward in Atlanta, USA. As you may understand, we had to decide to move this year's conference online, but it will be just as important as ever to attend and to present your work to your colleagues, and learn from each other. While we all wish to meet in person, one advantage of the online format is that it will allow for more individuals to participate, and we will aim to keep costs low. 
We are pleased to inform that abstract submissions are now accepted for the upcoming CDI&E virtual 2021 conference through our conference website https://www.cdie2021.com/. Deadline for abstract submissions is: March 8th, 2021.
More information regarding the virtual platform, conference timing, and cost will be announced on the conference website. We anticipate registration cost around $100 USD, with a reduced fee for graduate students. Registration information will be sent to you after your abstract has been received. 

Best regards,
Marta Hatzell, Roland Cusick and Xiao Su

Yesterday a new OPEN ACCESS review was published in the prestigious RSC journal Energy & Environmental Science (impact factor 33), which was composed by an international consortium of authors from The Netherlands (Wageningen University & Research, Wetsus), USA (Yale University), Israel (Technion), South Korea (Seoul National University), and China (Tsinghua University). It features a comprehensive analysis of different approaches in utilizing capacitive deionization (CDI) for selective ion separation, as well as a new theory of selective ion separation for intercalation materials. Please access the paper here, and a recent press release can be found here.

Maarten Biesheuvel (Wetsus) and Jouke Dykstra (Wageningen University), members of the CDI&E working group, are pleased to announce the release of their second book in their series on “Physics of Electrochemical Processes”. This book focuses more strongly on electrode processes and is therefore relevant to the CDI community. Both books can still be downloaded free-of-charge from the website www.physicsofelectrochemicalprocesses.com.

The new book is titled “Introduction to Physics of Electrochemical Processes” and focuses on electrode processes. One of the topics addressed is the important difference between Faradaic processes that can run forever such as fuel cells, and capacitive (i.e., non-Faradaic) processes, such as ion storage in porous electrodes, where the electrode structure continuously changes upon charging and discharging the electrode, irrespective of the details of the chemistry of the electrode material. Your comments are welcome and can be addressed to the authors via the website. To be updated on new releases, please visit the website, and leave your email address there.

The pre-release of the book 'Physics of Electrochemical Processes' (ISBN: 9789090332581) by P.M. Biesheuvel and J.E. Dykstra can now be downloaded from the website www.physicsofelectrochemicalprocesses.com free of charge.

Topics include:

  • Ch. 1: The extended Frumkin isotherm describes the capacitive salt adsorption in intercalation materials
  • Ch. 2: The Donnan model for the electrical double layer structure in charged materials, including electrodes
  • Ch. 3: The Gouy-Chapman-Stern model and surface ionization
  • Ch. 4: Volume effects in EDL theory (Bikerman, Carnahan-Starling, activity coefficients)
  • Ch. 5: EDLs in motion: electrowetting, contact angle, energy harvesting
  • Ch. 6: EDL interaction (DLVW theory)
  • Ch. 7: Solute Transport (mass transfer to interfaces including dispersion)
  • Ch. 8: Electrokinetics (hydrostatic and osmotic pressure, Navier-Stokes equation for electrolytes, osmosis vs electro-osmosis)
  • Ch. 9: Heat effects for current flow across the EDL (Peltier effect, electrostatic cooling)
  • Ch. 10: Acid-base reactions in transport models
  • Preamble: The microscopic and experimental perspective of the electrical double layer
  • Ch. 11: The difference between capacitive (non-Faradaic) and Faradaic electrode processes in electrochemistry
  • Ch. 12: Electrode kinetics (in preparation)
  • Ch. 13: Porous electrodes (in preparation)
  • Ch. 14: Reverse Osmosis
  • Ch. 15: Electrodialysis
  • Ch. 16: Ion transport in bio-electrochemical systems
  • Ch. 17: Bioelectrochemical conversions on conductive media
  • Ch. 18: Overview of electrochemical water desalination (in preparation)
  • Ch. 19: Numerical methods (2021)
  • Ch. 20: Analysis of experimental methods in electrochemistry (2021)

A new open access paper was recently published in Desalination that compares the energy use of RO and CDI.

Porada et al. “Energy consumption in membrane capacitive deionization and comparison with reverse osmosis”, Desalination (2020), https://doi.org/10.1016/j.desal.2020.114383. 

According to the authors, "the work presents the first fair energy consumption comparison of desalination with MCDI and RO. The comparison is based on experimental data, and the data is compared with results from state-of-the-art theoretical models. We find that the energy consumption difference between RO and CDI is much less than recently reported by the group of Prof. Elimelech (Yale, USA), see weblink."

The authors emphasize that two technologies can only be compared when all metrics are used in the same uniform way, and when for each technology state-of-the-art is considered. A new operational mode for CDI is introduced with a long "hold time" during salt release, leading to unprecedented high values of water recovery obtained in CDI with high feed water salinity of 40 mM NaCl solution. 

 

A new Open Access paper was published in the prestigious journal ES&T, from the group of prof. Meny Elimelech (Yale, USA) which discusses a detailed comparison between electrodialysis (ED) and membrane capacitive deionization (MCDI).

Patel et al. "Energy Efficiency of Electro-Driven Brackish Water Desalination: Electrodialysis Significantly Outperforms Membrane Capacitive Deionization", ES&T (2020). https://pubs.acs.org/doi/abs/10.1021/acs.est.9b07482

According to the authors, "we provide the first systematic and rigorous comparison of the energetic performance of electrodialysis (ED) and membrane capacitive deionization (MCDI) over a broad range of brackish water desalination conditions."

The authors find that:

  • The energy consumption of ED is substantially lower than MCDI for all investigated conditions, with the energy efficiency being nearly an order of magnitude higher for many separations.
  • Even with idealized operation (complete energy recovery and reduction in energetic losses), the energy efficiency of MCDI remains lower than ED.

Finally, the authors emphasize that "for low feedwater salinities (< ~2 g/L), energy efficiency should be a secondary consideration in the choice of desalination technology, with capital cost, ease and reliability of operation, and additionally required treatment steps taking higher priority."

... and the field of Capacitive Deionization keeps on growing at an increasing speed ! With over 160 scientific papers written and published last year, the total number of CDI publications has grown from ∼25 in 2000, to ∼65 in 2010, to over 1,000 at the end of 2019! CDI papers in 2019 came from many prestigious places including Tsinghua University, Seoul National University, Technion, MIT, Stanford, and Yale. This output from such eminent research groups shows that CDI is taking a leading role in the scientific study of water desalination technologies. Analyzing these publication data for the past decade, an exponential growth can be observed, with a doubling of the publication output every 2.5 year !

Citations to the CDI literature have grown from a number less than 100 per year before 2010, to about 2000 per year at the end of 2015, and close to 10,000 per year in 2019. These statistics also reflect an exponential growth, with a doubling time of 2.0 year. This difference in doubling time (faster for citations than publications) may indicate that CDI papers are more and more cited in papers from outside the CDI-field.

We are honored to introduce the 5th International conference on capacitive deionization and electrosorption, which will take place in Atlanta, GA, United States on May 11th-14th, 2021.  The conference will be a good forum for CDI researchers to present new results, draw inspiration, and direct future growth into CDI&E research. We would be grateful for your attendance and participation in this event. To stay up to date with conference preparations, please see our conference website (https://www.cdie2021.com/) or follow us on Twitter (@CDIe_2021).