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.

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