Citation: Senevirathna, H.L.;
Weerasinghe, P.V.T.; Xu, L.; Tan, M.-Y.;
Kim, S.-S.; Wu, P. Counter-Intuitive
Magneto-Water-Wetting Effect to
CO
2
Adsorption at Room
Temperature Using MgO/Mg(OH)
2
Nanocomposites. Materials 2022, 15,
983. https://doi.org/10.3390/
ma15030983
Academic Editor: Paula Teixeira
Received: 20 December 2021
Accepted: 19 January 2022
Published: 27 January 2022
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materials
Article
Counter-Intuitive Magneto-Water-Wetting Effect to CO
2
Adsorption
at Room Temperature Using MgO/Mg(OH)
2
Nanocomposites
Hasanthi L. Senevirathna
1
, P. Vishakha T. Weerasinghe
1
, Li Xu
2
, Ming-Yan Tan
2
, Sang-Sub Kim
3,
*
and Ping Wu
1,
*
1
Entropic Interface Group, Engineering Product Development, Singapore University of Technology and
Design, 8 Somapah Road, Singapore 487372, Singapore; hasanthi_senevirathna@mymail.sutd.edu.sg (H.L.S.);
puwakdandawe@mymail.sutd.edu.sg (P.V.T.W.)
2
Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR),
2 Fusionopolis Way, Innovis, #08-03, Singapore 138634, Singapore; x-li@imre.a-star.edu.sg (L.X.);
tanmy@imre.a-star.edu.sg (M.-Y.T.)
3
Department of Materials Science and Engineering, Inha University, Incheon 22212, Korea
* Correspondence: sangsub@inha.ac.kr (S.-S.K.); wuping@sutd.edu.sg (P.W.)
Abstract: MgO/Mg(OH)
2
-based materials have been intensively explored for CO
2
adsorption due
to their high theoretical but low practical CO
2
capture efficiency. Our previous study on the effect
of H
2
O wetting on CO
2
adsorption in MgO/Mg(OH)
2
nanostructures found that the presence of
H
2
O molecules significantly increases (decreases) CO
2
adsorption on the MgO (Mg(OH)
2
) surface.
Furthermore, the magneto-water-wetting technique is used to improve the CO
2
capture efficiency of
various nanofluids by increasing the mass transfer efficiency of nanobeads. However, the influence
of magneto-wetting to the CO
2
adsorption at nanobead surfaces remains unknown. The effect of
magneto-water-wetting on CO
2
adsorption on MgO/Mg(OH)
2
nanocomposites was investigated
experimentally in this study. Contrary to popular belief, magneto-water-wetting does not always
increase CO
2
adsorption; in fact, if Mg(OH)
2
dominates in the nanocomposite, it can actually decrease
CO
2
adsorption. As a result of our structural research, we hypothesized that the creation of a thin H
2
O
layer between nanograins prevents CO
2
from flowing through, hence slowing down CO
2
adsorption
during the carbon-hydration aging process. Finally, the magneto-water-wetting technique can be
used to control the carbon-hydration process and uncover both novel insights and discoveries of CO
2
capture from air at room temperature to guide the design and development of ferrofluid devices for
biomedical and energy applications.
Keywords: room temperature; CO
2
adsorption; magneto-wetting; nesquehonite; aging
1. Introduction
At present, renewable energy sources are garnering much attention due to their
many advantages, including many environmental benefits [1]. However, in spite of the
advantages, the majority of the energy requirements are fulfilled by utilizing fossil fuels.
There are many adverse effects associated with anthropogenic activities, especially fossil
fuel combustion, which contributes to the emission of carbon dioxide gas at an alarming
rate. Compelling evidence supports the fact that the constant emission of CO
2
gas into the
atmosphere is the leading cause of global warming. Apart from that, accumulated gas in
the atmosphere brings a series of adverse events such as air pollution, extreme weather
conditions, etc. Hence, high levels of CO
2
in the atmosphere are an alarming threat to all
living beings in the world. Therefore, to mitigate these negative impacts, CO
2
capture, and
storage have gained the great interest of many research groups.
Consequently, the use of sorbent materials for carbon capture has received a great
deal of attention. These materials include both solid and liquid-based materials. Solid
adsorbents have its advantages over liquid adsorbents [2]. The use of solid adsorbents,
Materials 2022, 15, 983. https://doi.org/10.3390/ma15030983 https://www.mdpi.com/journal/materials