Hierarchical Porous Carbon for High-Performance Capacitive Desalination of Brackish Water

Abstract

Capacitive deionization (CDI), as an energyefficient and promising brackish water desalination technique, has certain advantages over conventional methods such as thermal distillation, ultrafiltration, and reverse osmosis. However, CDI technology is as yet not widely applied as it can only treat low salinity water due to the limitation of salt adsorption capacity of the electrode. The complexity and high cost of the preparation of such materials with excellent salt removal capability also hinder the commercialization of CDI technology. To surmount these barriers in CDI technology, we hereby developed a hierarchical porous carbon (h-PC) which was prepared via a facile, economic, and green calcination of biomass mixed with an activator. Our prepared h-PC electrodes demonstrate an outstanding salt adsorption capacity (SAC) of 83.0 mg/g when the NaCl concentration is 1000 mg/L for batch mode CDI. This SAC is significantly higher than those reported elsewhere (normally between 15−25 mg/g), and the ultrahigh SAC may be due to the high specific surface area (SSA) and favorable hierarchical pore structure of h-PC. The as-prepared h-PC can also effectively remove heavy metals and desalinate brackish water with a wide range of salinity up to 10000 mg/L. Furthermore, the h-PC-800 electrode shows outstanding cycling stability with no decline of salt adsorption capacity or its corresponding charge efficiency in the long term continuous mode CDI process (over 200 cycles). Our study of this work may be helpful in the design of practical and economical material for highperformance CDI application of the desalination of brackish water with various salinity.

Electrochemically mediated deionization: a review

“…8a). 44,73 Despite similarly high performance, the two structures were fabricated with entirely different procedures: one via self-assembly of block copolymer fibers and the other via calcination of biomass with an activator to create micropores.…”

Self-Supporting Nanoporous Copper Film with High Porosity and Broadband Light Absorption for Efficient Solar Steam Generation

“…Some traditional desalination methods (such as multistage flash distillation [ 9 ] and reverse osmosis [ 10 ]) require a lot of energy [ 11 ] and pollutants generated by burning fossil fuels have a negative impact on the environment [ 12 ]. Other desalination methods such as electrodialysis and emerging capacitive deionization, which are not suitable for seawater with high salt concentrations [ 13 , 14 ]. So solar steam generation (SSG) using solar energy to desalinate seawater has been considered as one of the most attractive desalination technologies [ 15 , 16 ].…”

Designing of a Free-Standing Flexible Symmetric Electrode Material for Capacitive Deionization and Solid-State Supercapacitors

“…Every year, a substantial amount of biomass is produced. Active carbons generated from biomasses have been employed in supercapacitors and CDI extensively because of their properties mentioned earlier and their huge surface area. − Despite their high SSA, they offer relatively low capacitance and electrosorption capacity due to the following probable factors. One reason for the low capacitance values is the lengthy, tortuous micropores’ weak electronic conductivity and insufficient ion diffusion, and the others are the pore width, pore size distribution, and surface morphology.…”