The present
study is focused on green technology for converting cigarette filters
(CFs) into cigarette carbonaceous (CC) hydrochar as a useful product
with added value and lower toxicity. This work was aimed at three
primary environmental goals: first, the valorization of CFs by their
conversion into a novel adsorbent as a cheap and economic source;
second, this structure can offer highly stable and reactive support
for growing ZIF-67 metal–organic framework (MOF); and third,
the CC-hydrochar/ZIF-67 nanofluids can be employed for the CO2 capture process in a newly designed packed column. CC-hydrochar/ZIF-67
was characterized through FTIR, XRD, FESEM, and BET analyses. The
CC-hydrochar/ZIF-67 nanofluid was prepared by a simple and surfactant-free
method and characterized by zeta potential and DLS analyses. Its CO2 capture performance was then evaluated in aqueous media.
The capture tests were conducted in a packed bed column, while the
central composite design was used to understand the interactions among
the operational parameters, including CC-hydrochar/ZIF-67 loading,
liquid flow rate, gas flow rate, and CO2 initial concentration.
The obtained results indicated the maximum CO2 capture
percentage (98.02%) at the optimum conditions involving a CC-hydrochar/ZIF-67
loading of 0.06 g/L, a liquid flow rate of 0.40 L/min, a gas flow
rate of 3.00 m3/h, and a CO2 initial concentration
of 4500 ppm. Finally, the mass-transfer performance was evaluated
in the applied absorbents by the calculation of the overall mass-transfer
coefficient per unit volume (K
G
a), the height of transfer unit (HTU), the number of transfer
unit (NTU), and the total height of packing in the column (Z). The results indicated that the CC-hydrochar-ZIF-67 nanofluid
could be considered as an efficient and economical alternative for
conventional absorbents.