Controlling hierarchical porous structures of rice-husk-derived carbons for improved capacitive deionization performance

Jiyoung Kim, Yilhoon Yi, Dong Hyun Peck, Seong Ho Yoon, Doo Hwan Jung, Ho Seok Park

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We report on hierarchical porous carbons derived from rice husk (RH) through the combination of carbonization and two post-processing methods that were used as the electrode material for capacitive deionization (CDI). The carbonized RHs, consisting of carbon/inorganic composite materials, were used to control the hierarchical porous structures, depending on the existence of silicon domains. Hierarchical porous carbons, denoted as RHC-A and comprising dominant micropores and small fraction mesopores, were synthesized by steam activation to react with the carbon fraction in the presence of silicon components. On the other hand, mesopore-dominant porous carbons, denoted as RHC-H, were obtained selectively by removing silicon components acting as a natural template from carbonized RH by hydrofluoric acid treatment. In order to understand the effect of the pore structure on CDI performance, two RH-derived porous carbons were compared in terms of their performances in water purification. In the batch-mode experiment, the microporous activated carbon (AC) exhibited the highest maximum electrosorption capacity of 17.7 mg g-1, which was mainly determined by the specific surface area. Under the same conditions, however, the RHC-A was verified to have enhanced kinetic performance according to the Langmuir isotherm and the pseudo-second-order kinetic model. Here, the hierarchical porous structures with continuous mesopores interconnected by micropores contributed to the enhanced kinetic performance of the RHC-A, facilitating effective ion transport and adsorption. In a continuous mode similar to the practical CDI, the kinetically improved RHC-A achieved a higher salt-removal capacity of 8.09 mg g-1 than the 5.40 mg g-1 and 1.63 mg g-1 of the commercial activated carbon and RHC-H, respectively, at 1.5 V and with a feed rate of 20 mL min-1 in 100 ppm of NaCl solution.

Original languageEnglish
Pages (from-to)916-924
Number of pages9
JournalEnvironmental Science: Nano
Volume6
Issue number3
DOIs
Publication statusPublished - Jan 1 2019

Fingerprint

Carbon
rice
carbon
silicon
Silicon
kinetics
activated carbon
Activated carbon
Kinetics
hydrofluoric acid
Hydrofluoric Acid
inorganic carbon
Salt removal
Hydrofluoric acid
Steam
Carbonization
Pore structure
isotherm
electrode
Specific surface area

All Science Journal Classification (ASJC) codes

  • Materials Science (miscellaneous)
  • Environmental Science(all)

Cite this

Controlling hierarchical porous structures of rice-husk-derived carbons for improved capacitive deionization performance. / Kim, Jiyoung; Yi, Yilhoon; Peck, Dong Hyun; Yoon, Seong Ho; Jung, Doo Hwan; Park, Ho Seok.

In: Environmental Science: Nano, Vol. 6, No. 3, 01.01.2019, p. 916-924.

Research output: Contribution to journalArticle

Kim, Jiyoung ; Yi, Yilhoon ; Peck, Dong Hyun ; Yoon, Seong Ho ; Jung, Doo Hwan ; Park, Ho Seok. / Controlling hierarchical porous structures of rice-husk-derived carbons for improved capacitive deionization performance. In: Environmental Science: Nano. 2019 ; Vol. 6, No. 3. pp. 916-924.
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