In this study, we compared the conversion of polyethylene terephthalate (PET) into porous carbons for water purification using pyrolysis and post-activation with KOH. Pyrolysis was conducted at 400–850 °C, followed by KOH activation at 850 °C for samples pyrolyzed at 400, 650, and 850 °C. Both pyrolyzed and post-activated carbons showed high specific surface areas, up to 504.2 and 617.7 m² g⁻¹, respectively. As the pyrolysis temperature increases, the crystallite size of the graphite phase rises simultaneously with a decrease in specific surface area. This phenomenon significantly influences the final specific surface area values of the activated samples. Despite their relatively high specific surface areas, pyrolyzed PET-derived carbons prove unsuitable as adsorbents for purifying aqueous media from methylene blue dye. A sample pyrolyzed at 650 °C, with a surface area of 504.2 m² g⁻¹, exhibited a maximum adsorption value of only 20.4 mg g⁻¹. We propose that the pyrolyzed samples have a surface coating of amorphous carbon poor in oxygen groups, impeding the diffusion of dye molecules. Conversely, post-activated samples emerge as promising adsorbents, exhibiting a maximum adsorption capacity of up to 127.7 mg g⁻¹. This suggests their potential for efficient dye removal in water purification applications.

Iron catalysts supported on an activated fibrous carbon material (AFCM) and characterized by high performance in the hydrocarbon synthesis from CO and H₂ have been studied. It has been shown that the promotion of Fe/AFCM catalysts with potassium and aluminum oxides or with copper reduces the optimum temperature of Fischer-Tropsch synthesis and enhances the polymerizing activity of the catalysts.