Livy Laysandra, Immanuel Joseph Ondang, Yi-Hsu Ju, Benedikta Hervina Ariandini, Agatha Mariska, Felycia Edi Soetaredjo, Jindrayani Nyoo Putro, Shella Permatasari Santoso, Farida Lanawati Darsono, Suryadi Ismadji
Robust and simple composite films for the removal of methyl orange (MO) and Cr(VI) have been prepared by combining chitosan, saponin, and bentonite at a specific ratio. There are several composite films (chitosan-saponin-bentonite (CSB)) prepared; among them, the composite films CSB 2:3 and CSB 1:1 have the highest removal efficiency toward MO and Cr(VI) where the maximum removal is 70.4% (pH 4.80) and 92.3% (pH 5.30), respectively. It was found that different types of adsorbate have different thermodynamic properties of the adsorption process; the adsorption of MO onto CSB 2:3 , chitosan, and acid-activated bentonite (AAB) proceeded endothermically, while the adsorption of Cr(VI) onto CSB 1:1 , chitosan, and AAB proceeded exothermically. The parameters of the adsorption were modeled by using isotherm and kinetic equations. The models of Langmuir, Freundlich, Redlich-Peterson, Sips, and Toth were used for fitting the adsorption isotherm data at a temperature of 30, 45, and 60 °C; all of the isotherm models could represent the data well. The result indicates that CSB 2:3 has the highest adsorption capacity toward MO with q m of 360.90 mg g −1 at 60 °C; meanwhile, CSB 1:1 has the highest adsorption capacity toward Cr(VI) with q m 641.99 mg g −1 at 30 °C. The pseudo-second-order model could represent the adsorption kinetics data better than the pseudo-first-order equation. The adsorption mechanism was proposed, and the thermodynamic properties of the adsorption were also studied. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Kalijudan 37, Surabaya, 60114, Indonesia; Graduate Institute of Applied Science, National Taiwan University of Science and Technology, 43 Keelung Road, Sec 4, Taipei, 10607, Taiwan; Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Sec 4, Taipei, 10607, Taiwan; Faculty of Pharmacy, Widya Mandala Surabaya Catholic University, Pakuwon City, Kalisari 1, Surabaya, 60112, Indonesia