Available at: https://digitalcommons.calpoly.edu/theses/3392
Date of Award
6-2026
Degree Name
MS in Civil and Environmental Engineering
Department/Program
Civil and Environmental Engineering
College
College of Engineering
Advisor
Amro El Badawy
Advisor Department
Civil and Environmental Engineering
Advisor College
College of Engineering
Abstract
Carbon dioxide (CO₂) emissions from fossil fuel combustion are a major contributor to climate change and its associated environmental impacts. The current standard technology for post-combustion carbon capture, aqueous amine scrubbing, is effective but requires significant regeneration energy and has high operational costs. As a result, solid sorbents have been investigated as lower-energy alternatives. Metal-organic frameworks (MOFs) are a promising class of porous nanomaterials due to their high surface area, tunable pore structures, and adjustable surface chemistry. Among them, zeolitic imidazolate framework-8 (ZIF-8) has high thermal and chemical stability, hydrophobicity, and favorable adsorption properties. However, conventional synthesis methods often rely on toxic organic solvents and energy-intensive processing conditions.
This study investigated the synthesis and characterization of a graphene oxide (GO) and ZIF-8 composite using an aqueous based, room temperature synthesis route. The synthesized GO@ZIF-8 composite, along with the parent materials GO and pristine ZIF-8 were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). XRD and FTIR analyses confirmed the successful synthesis of the parent materials and the integration of ZIF-8 onto GO sheets. Improper GO drying can disrupt the oxygen groups, leading to improper structural spacing and stacking instead of hybridization of GO and ZIF-8. A comparison of drying methods revealed that freeze-drying better preserved oxygen-containing functional groups in GO than conventional air drying. Thermal analysis provided insight into the stability of the synthesized materials and the effects of processing conditions.
The CO₂ sorption capacities of pristine ZIF-8 and GO@ZIF-8 were evaluated using a quartz crystal microbalance (QCM) under CO₂ partial pressures ranging from 0.167 to 1.0 atm to characterize the effect of various CO2 concentrations. Pristine ZIF-8 exhibited a higher average adsorption capacity than the GO@ZIF-8 composite, reaching 1.70 mmol g⁻¹ and 0.63 mmol g⁻¹ at 1 atm CO₂, respectively. However, significant variability was observed among replicate measurements due to limitations associated with microbalance quartz crystal reuse and experimental uncertainty. Consequently, the adsorption results were insufficient to definitively assess the impact of GO incorporation on CO₂ sorption performance.
Overall, this work demonstrated the feasibility of synthesizing a GO@ZIF-8 composite through a sustainable aqueous, room temperature synthesis route while identifying critical challenges associated with GO processing and adsorption testing. Future work should focus on improving GO drying methods, optimizing composite composition, and refining adsorption measurement procedures to fully evaluate the potential of GO@ZIF-8 composites for post-combustion carbon capture applications.