Articles in Press

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Summary:
Biogas and biomethane are renewable gases that should be strongly considered to accelerate decarbonization and reduce greenhouse gas emissions in many sectors. In addition, biomethane is important to provide renewable and more economical energy to consumers using the existing gas infrastructure. Moreover, biomethane can be easily stored and can be used as a balancer for intermittent renewable energy sources such as solar and wind. The EU considers bio-CNG (compressed), bio-LNG (liquefied) fuels to be an effective method in reducing emissions. Therefore, Europe leads the world in biogas and biomethane production. In this study, evaluations and general views were made about the definition of biogas and biomethane, production amounts in the world and purification methods (treatment) of biogas. The main purpose of the current study is to emphasize that biogas provides an important solution for decarbonization and that its usage areas can be expanded by purifying it as biomethane.

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Summary:
Surface modification approaches can improve the adsorbent's physicochemical characteristics, which are crucial to the adsorption process's effectiveness. In this study, the effects of chemical modification on the structural and chemical properties of four different powdered activated carbon (AC) samples were investigated. Surface modifications were performed using nitric acid and chlorosulfonic acid. The modified adsorbents were comprehensively characterized by Brunauer–Emmett–Teller (BET) surface area analysis, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Dynamic Light Scattering (DLS). Additionally, the Boehm titration method was employed to evaluate the surface acidity and functional group composition. According to the research results, nitric acid modification led to a smoother and more uniform surface morphology, along with a more consistent pore size distribution, compared to chlorosulfonic acid treatment. Nitric acid introduced functional groups such as –OH, –COOH, and C=C=C, while chlorosulfonic acid resulted in the incorporation of sulfonic groups (S=O and SO₃H). Among the modified samples, AC4S exhibited the highest surface area (868.48 m²/g) and pore volume (0.88 cm³/g). The largest average particle size (1419.44 nm) was observed in the AC1S sample. While double modification increased particle size distribution, it negatively affected surface area and pore volume. Overall, the findings indicate that both nitric acid and chlorosulfonic acid modifications are effective in tailoring the chemical and structural features of activated carbon, offering promising potential for adsorption-based applications.