Application of modified nanoporous materials in ascorbic acid adsorption

In this study, three types of mesoporous materials Santa Barbara no. 15 (SBA-15), carbon mesostructured by KAIST (CMK-3), and modified carbon mesostructured by KAIST (modified CMK-3) were prepared and their capability as sorbents for vitamin C (ascorbic acid) adsorption from aqueous solutions was compared with each other. Cetyltrimethylammonium bromide (CTAB) was used for surface modification of CMK-3. The structures of different adsorbents were characterized by X-ray diffraction (XRD) and N-2 adsorption measurements, and the functionalization of CMK-3 was proved by XRD technique. The adsorption isotherms, sorption kinetics as well as the effects of some parameters such as pH value of the vitamin solution, adsorption time, and the initial vitamin concentration on the adsorption capacity of the analyte on CTAB/CMK-3 were investigated. It was found that the ultimate capacity of the adsorbents varied in the order CTAB/CMK-3 > CMK-3 > SBA-15. Langmuir and Freundlich isotherm models have been used to fit equilibrium data for CTAB/CMK-3. The equilibrium data were best represented by the Langmuir isotherm. Kinetic studies were performed and it was determined that the sorption kinetics of vitamin C was truly described by a pseudo-second-order kinetic model.