## 4 Conclusions and Future Directions  
In this study, we successfully synthesized ZIF-8 particles of varying sizes using a rapid synthesis method. The formation of ZIF-8 was confirmed through XRD and microstructural analysis. Additionally, we developed a ZIF-8-based cellulose air filter (ZCAF) by incorporating ZIF-8 crystals into bleached softwood kraft pulp. The particle sizes of the synthesized ZIF-8 samples were determined to be approximately 99.46 nm, 101.9 nm, and 105.7 nm. Our objective was to create an air filter for CO\({}_{2}\) capture using ZIF-8. To evaluate the CO\({}_{2}\) adsorption capacity, we calculated the CO\({}_{2}\) loading for both ZIF-8 and ZCAF samples, comparing them with a standard MEA solution. The results revealed that the ZIF-8 sample with the smallest particle size (ZS3) exhibited a significant increase of approximately 41% in CO\({}_{2}\) loading compared with the MEA reference. Similarly, the ZCAF sample (ZCAF3) demonstrated a 22% increase in CO\({}_{2}\) loading relative to the MEA reference. These findings indicate that ZIF-8, especially when composed of smaller particles, enhances CO\({}_{2}\) capture both independently and when incorporated into the ZCAF. Our study demonstrates that ZIF-8 particles with smaller sizes contribute to improved CO\({}_{2}\) capture efficiency, both in standalone form and when integrated into the ZCAF. The following are significant conclusions and future directions of the present study:  
The integration of ZIF-8 into cellulose matrices (ZCAFs) significantly enhances CO\({}_{2}\) adsorption efficiency, validating the potential of ZIF-8 as a highly effective additive for improving the performance of traditional CO\({}_{2}\) capture materials like MEA. The findings highlight that ZIF-8 particle size and its distribution within the cellulose matrix play crucial roles in determining CO\({}_{2}\) adsorption capacity. This study suggests that even slight variations in particle size can lead to significant differences in performance, emphasizing the need for precise control over synthesis conditions. While higher ZIF-8 content increases CO\({}_{2}\) loading, there is a critical need to balance this with the mechanical properties of the composite. Excessive ZIF-8 loading could compromise the material's flexibility and robustness, which are essential for practical filter applications. The ability to fine-tune the ZIF-8 content in the cellulose matrix suggests that the material can be customized for specific applications, offering a versatile approach to CO\({}_{2}\) capture across different industrial contexts. Future research could explore the functionalization of ZIF-8 particles with various chemical groups (e.g., amines) to further enhance CO\({}_{2}\) capture efficiency, potentially leading to materials with even greater adsorption capacities. Investigating alternative synthesis methods or optimizing existing techniques to improve the dispersion and adhesion of ZIF-8 particles in the cellulose matrix could yield composites with better performance and mechanical properties. Conducting long-term stability and durability tests under real-world operating conditions (e.g., varying temperatures, humidity, and pressure) will be crucial to assess the practical viability of ZCAF filters in industrial CO\({}_{2}\) capture applications. Future work should include the scale-up of ZCAF production processes and economic analysis to determine the feasibility of implementing these materials on an industrial scale for large-scale CO\({}_{2}\) capture operations. An in-depth environmental impact assessment, including lifecycle analysis (LCA), should be conducted to understand the sustainability and ecological footprint of producing and deploying ZIF-8-based cellulose filters compared with conventional CO\({}_{2}\) capture technologies. Investigating other biopolymer matrices beyond cellulose, such as chitosan or alginate, could offer alternative composites with unique properties that might further enhance CO\({}_{2}\) capture efficiency or mechanical strength.