Performance of dry water- and porous carbon-based sorbents for carbon dioxide capture

Mohammad Al-Wabel, Jamal Elfaki, Adel Usman, Qaiser Hussain, Yong Sik Ok

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Abstract

Carbon dioxide is the primary greenhouse gas that has a strong impact on global warming. Several technologies have been developed for capturing CO 2 to mitigate the greenhouse effect. The objective of this research was to investigate the performance of several sorbents based on dry water and porous carbon materials for capturing CO 2 . Seven sorbents were prepared and comparatively evaluated for their CO 2 capture capabilities: (i) Conocarpus biochar (CBC); (ii) commercial activated carbon (CAC); (iii) normal dry water (NDW); (iv) K 2 CO 3 -treated CBC (TCBC); (v) K 2 CO 3 -modified dry water (MDW); (vi) MDW and 2% TCBC (MDWTCBC); and (vii) MDW and 2% activated carbon (MDWCAC). The sorption process was carried out with initial CO 2 concentration of 5.7%, temperature of 25 °C, feed gas flow rate of 0.5 l min −1 and a pressure of 1.0 bar. The pure CO 2 was mixed with O 2 or N 2 to achieve the desired inlet concentration of CO 2 . The CO 2 adsorption capacity and partition coefficient (PC) of the tested sorbents were evaluated at 5% and 100% breakthrough (BT). The results showed a longer breakthrough and equilibrium adsorption times for CO 2 when mixed with N 2 than with O 2 . Among all sorbents, both CAC and CBC showed enhanced CO 2 capture performance with equilibrium (100% BT) adsorption capacities of 239 and 197 mg g −1 , respectively (in terms of PC: 1.0 × 10 −3 and 7.9 × 10 −4 mol kg −1 Pa −1 , respectively). In contrast, the performance of TCBC and the dry water-based sorbents was far lower than CAC or CBC. The CO 2 adsorption data fitted well to the non-linearized form of the pseudo-first-order kinetic model. The Fourier-transform infrared spectral patterns indicated that the reaction of CO 2 molecules with the hydroxyl groups of sorbents is possible through the formation of chemisorbed CO 2 species. It could be concluded that the activation process did not play a role in increasing the CO 2 capture performance in order to form new active sorption sites. However, Conocarpus biochar can be used as efficient sorbent for CO 2 capture with a better performance than other materials tested previously (e.g., activated carbon).

Original languageEnglish
Pages (from-to)69-79
Number of pages11
JournalEnvironmental Research
DOIs
Publication statusPublished - 2019 Jul 1

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Keywords

  • Activated carbon
  • Biochar
  • CO adsorption
  • Dry water
  • Gas adsorbent
  • Partition coefficient

ASJC Scopus subject areas

  • Biochemistry
  • Environmental Science(all)

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