Investigation of hydrogen and carbon dioxide adsorption capacity of acid pre-treated natural bentonite

Both alternative energy sources and carbon reduction activities have gained great importance as a result of meeting the ever-increasing energy demand, which are the negative consequences of increasing consumption habits, and the environmental damage caused by air pollution emissions resulting from industrial activities. Developing storage technologies for the widespread and safe use of hydrogen, which is one of the prominent alternative solutions in this direction, is an important issue. On the other hand, due to the fact that traditional methods are still being used in hydrogen production, the increase in CO2 emission resulting from other energy, industrial and individual activities and the necessity to develop various carbon capture alternatives for its reduction brings the issue of gas adsorption to the forefront. While porous structures come to the fore in physical adsorption, natural or artificial clay structures with a highly porous structure attract attention as a good alternative. Thanks to both physical and chemical structure advantages, they are very suitable for adsorption of gases such as H2 and CO2. While our country has significant reserves of different zeolite minerals, one of the most abundant among them is bentonite. Thanks to the structural advantages of bentonite, it can be used as an adsorbent. The utilization of such a resource, which is abundant in our country, in two different areas such as produced and waste gas, has a significant impact on environmental sustainability, resource sustainability and economic sustainability. Although bentonites are suitable for use as adsorbents in their current form, literature studies indicate that the adsorbent capabilities of bentonite and other zeolite species are significantly improved when various pretreatments are applied. Considering energy and environment as an inseparable whole, adsorption of both produced and operational emissions is an important area to be studied. Gas adsorption is also considered as an important treatment technique in terms of emissions. Therefore, the aim of this study was to prepare a readily available, economical, suitable for chemical and thermal pretreatments, and highly adsorptive H2 and CO2 adsorbent material. For this purpose, after pretreatment of bentonite with HCl at 65AQ< 462 and 85⁰C temperatures and 0.2M, 0.5M and 1M concentrations, the changes in the structure of natural and activated bentonites and the changes in their properties such as surface area and gas adsorption capacity were compared. As a result of the investigations, it was determined that increasing temperature and acid concentration provided positive modifications on the physical and chemical structures of bentonite. The changes in the structure of bentonite were observed by XRD analysis in the diffraction of crystals, by FTIR analysis in the change of groups in its structure, by TG-DTA analysis in the determination of weight loss with increasing temperature, by SEM images, and by EDS analysis in the structure of bentonite. In the BET surface area studies, it was found that the highest surface area value was 70.8 m2/g, the highest N2 adsorption was 78.52 cm3/g, the highest H2 adsorption capacity was 51.07 cm3/g and the highest CO2 adsorption capacity was 2.32 cm3/g.