Implementation of carbonated water in the enhanced oil recovery (EOR) process for oil reservoirs by increasing the carbon dioxide (CO2) content in water causes interfacial tension (IFT) between oil and carbonated water to decline, thereby increasing the areal sweep efficiency as well as oil recovery. For this reason, the main purpose of this research was to examine the effect of using polymer-based Fe3O4 nanoparticles (NPs) on the amount of CO2 absorption in distilled water under different conditions (pressure: 20-40 bar, temperature: 35-60 degrees C, concentration of NPs: 0.01 to 0.14 wt %). To this end, two experimental setups were employed to measure the amount of CO2 absorption in water in the presence of bare Fe3O4 NPs, Fe3O4 NPs coated by poly(vinyl alcohol) (FPVA), and Fe3O4 NPs coated by polyacrylamide (FPAM) synthesized by the co-precipitation technique, and the IFT between oil and carbonated water. The results revealed that the presence of FPVA and FPAM NPs in water causes the amount of CO2 absorption to enhance up to 20.2 and 23.3%, respectively, as compared to water alone at 40 bar. Subsequently, to evaluate the potential of the synthesized NPs in reducing capillary pressure in oil reservoirs, the interfacial tension (IFT) between carbonated water containing each of these three NPs alone with the concentration of 0.01 wt % (Fe3O4, FPVA, FPAM NPs) and oil at various pressures and temperatures up to 80 bar and 80 degrees C, respectively, was measured. The results demonstrated that a maximum reduction in the IFT between oil and carbonated water in the presence of modified Fe3O4 NPs was found (31.91%) as compared to bare Fe3O4 NPs under the conditions investigated in this work. Eventually, it was observed that the modified NPs (i.e., FPVA and FPAM NPs) effectively enhanced the properties of the bare Fe3O4 NPs by improving the hydrophilicity of the carbonate rock surface.