Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc Experimental and computational investigation on interaction mechanism of Rhodamine B adsorption and photodegradation by zeolite imidazole frameworks-8 Vy Anh Tran a,b , Khanh B. Vu c,d , Thu-Thao Thi Vo e , Van Thuan Le f,g , Ha Huu Do h , Long Giang Bach i, ⁎ , Sang-Wha Lee a, ⁎ a Department of Chemical and Biological Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si 13120, Republic of Korea b Institute of Research and Development, Duy Tan University, Danang 550000, Viet Nam c Department of Chemical Engineering, School of Biotechnology, International University, Ho Chi Minh City, Viet Nam d Vietnam National University, Ho Chi Minh City, Viet Nam e Department of Food Science and Biotechnology, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si 13120, Republic of Korea f Center for Advanced Chemistry, Institute of Research and Development, Duy Tan University, Da Nang, 550000, Viet Nam g The Faculty of Environmental and Chemical Engineering, Duy Tan University, Da Nang, 550000, Viet Nam h School of Chemical Engineering and Materials Science, Institute of Interdisciplinary Convergence Research, Chung- Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea i NTT Hi-Tech Institute, Nguyen Tat Thanh University, 298-300A Nguyen Tat Thanh, Ward 13, District 4, Ho Chi Minh City, Viet Nam ARTICLE INFO Keywords: Zeolite imidazole frameworks Adsorption–degradation mechanism 13 C NMR Rhodamine B Density functional theory ABSTRACT The adsorption of Rhodamine B (Rh.B) was achieved by Zeolite imidazolate framework-8 (ZIF-8) in the dark condition, and the adsorption rate was noticeably increased under visible and UV light irradiations. According to fuorescence spectroscopic studies, ZIF-8 under UV light generated hydroxyl radicals for the efective de- gradation of Rh.B dyes. These featured mechanisms were systematically elucidated by investigating the zeta potentials of ZIF-8/Rh.B; blue-shifted π –π* transition of aromatic system; chemical shift of 13 C NMR spectra; FTIR spectra; and high surface area and abundant mesopores of ZIF-8. Furthermore, the interaction mechanism between Rh.B with ZIF-8 was studied using a density functional theory (DFT) coupled with a spectroscopic technique. Herein, nine ZIF-8 clusters and Rh.B molecules were optimized in aqueous solution using the po- larizable continuum model to address the solvation efect. The DFT calculations suggested that π-π stacking interactions between the xanthene ring of Rh.B and the imidazole rings of ZIF-8 and electrostatic interactions between electron-defcient Zn centers and Rh.B predominantly contributed to the adsorption of Rh.B on the ZIF- 8. The experimental and computations studies provide a new insight for the sophisticated design of ZIF-8 na- nostructures for removing organic pollutants efciently through the combined adsorption and degradation under solar light irradiation. 1. Introduction In recent years, a variety of physicochemical treatment methods, including advanced oxidation, electrochemistry, biodegradation, coa- gulation, sedimentation, membrane technology, and adsorption have been applied for the efective removal of organic pollutants from aqu- eous solutions [1–3]. Among them, adsorption has become the most competitive method that is commonly employed for removing con- taminants in the wastewater due to its simplicity, mild operating con- ditions, and low cost [4,5]. Some adsorbents, such as carbon materials (graphene, carbon nanotubes and activated carbon) [6,7], minerals (kaolinite and montmorillonite) [8,9], polymers [10–13], and meta- l–organic frameworks (MOFs) [1,14–17] have been used to adsorb contaminants from water and exhibit good removal efciencies. Metal-organic frameworks (MOFs) are a class of highly porous materials that have drawn signifcant attention for potential applica- tions to drug delivery, gas separator, catalysis, adsorption/separation, and environmental remediation [14,18–24]. Since dye efuents are one of the largest pollutants in the world, it is challenging to develop sus- tainable adsorbent materials with a high adsorption capacity for https://doi.org/10.1016/j.apsusc.2020.148065 Received 29 June 2020; Received in revised form 20 September 2020; Accepted 3 October 2020 ⁎ Corresponding authors at: Department of Chemical and Biological Engineering, Gachon University, San 65, Bokjeong-Dong, Sujeong-Gu, Seongnam-Si 461-701, South Korea (S.W. Lee). E-mail addresses: blgiang@ntt.edu.vn (L.G. Bach), lswha@gachon.ac.kr (S.-W. Lee). Applied Surface Science 538 (2021) 148065 Available online 06 October 2020 0169-4332/ © 2020 Elsevier B.V. All rights reserved. T