Modified mesoporous silica derived from bamboo leaf using cetyltrimethylammonium bromide and 3-aminopropyl...

The calorific value of post-fermentation biogas is a way down below standard and quite low due to the presence of high amount level of carbon dioxide (CO₂) biogas mixture. Therefore, it raises the need to process the biogas, separating it from CO₂ in order to obtain high-purity biogas as well as to maximize its calorific value. One widely available material that can be used as a sustainable carbon capture adsorbent is silica extracted from bamboo leaves. However, so that silica can act as CO₂ adsorber, it is necessary to modify the surface of silica with CTAB and APTES (3-aminopropyl triethoxysilane). In this study, 2-stage method was carried out, namely preparation of mesoporous silica and surface modification using APTES on the mesoporous silica. Experiments in synthesizing APTES-modified silica were obtained by varying its composition: CTAB (1.5-5%w), (HCl 1.5-5 N), and APTES (10-30%). A central composite design (CCD) was employed in exploring the interaction between all variables and also performed for the optimization. Through analysis of variance, it shows that optimum CO₂ adsorption capacity reaches 47.02 mg g^-1, by applying 4.98% of CTAB, 4.28 N of HCl and 10.08% of APTES. Pseudo-second-order kinetic and Redlich-Peterson isotherm models are more representative to show the adsorption behavior of CO₂ into the modified silica. The results show that the modified silica with APTES shows a prospective application of silica for CO₂ removal from biogas.