Development of Cigarette Carbonaceous Hydrochar/ZIF-67-Based Fluids for CO₂ Capture from a Gas Stream in a Packed Column: Mass-Transfer Performance Evaluation

Abstract

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.

Green Synthesis of Zeolitic Imidazolate Frameworks: A Review of Their Characterization and Industrial and Medical Applications

“…Then, the researchers assess the mass-transfer performance in the applied absorbents via computing the overall mass-transfer coefficient in each unit volume (KGa), the number of transfer units (NTU), the total height of packing in the column (Z), and the height of transfer unit (HTU). Finally, they propose CC-hydrochar-ZIF-67 nano-fluid as an effective and affordable alternative to conventional absorbents [124].…”

Porous Metal–Organic Frameworks for Carbon Dioxide Adsorption and Separation at Low Pressure

“…188 Jaberi et al utilized cigarette filters as the carbon source to generate cigarette carbon; the ZIF-67 was then grown on the cigarette carbon to form a composite adsorbent (CC-ZIF-67). 189 The prepared CC-ZIF-67 nanofluid passed through the packed bed column at a fixed liquid flow rate to increase the interface area between adsorbent and CO 2 . The adsorption experiments on the packed bed column indicated that a faster gas flow rate and liquid flow rate are not conducive to CO 2 capture.…”

Decomposition of N2O on ZIF-67-Derived Co/CoOx@Carbon Catalysts and SO2 Interference

“…and deformation vibration (C–H bond, O–H bond, N–H bond, etc.) in the frameworks . It should be noted that free water, associated water, and X–H groups (X presents C/N/O element, e.g., −CH 3 , N–H, C–H, etc.)…”

“…in the frameworks. 53 It should be noted that free water, associated water, and X−H groups (X presents C/N/O element, e.g., −CH 3 , N−H, C−H, etc.) in the frameworks were obviously removed after pyrolysis.…”