Visible–light driven photocatalytic degradation of bisphenol-A using ultrasonically synthesized polypyrrole/K-birnessite nanohybrids: Experimental and DFT studies Jannatun Zia, Mohamed Ajeer, Ufana Riaz ⁎ Materials Research Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025, India ARTICLE INFO ABSTRACT Article history: Received 20 August 2018 Revised 27 November 2018 Accepted 28 November 2018 Available online 13 December 2018 Although manganese oxides are known for their semiconductor characteristics, the photocatalytic performance of conducting polymer intercalated K-Birnessite (K-Bi) has not been explored till date. With the view to design a visible light driven organic–inorganic hybrid photocatalyst for rapid degradation of Bisphenol A (BPA), the present work reports the ultrasound-assisted green synthesis of K-Bi/polypyrrole (Ppy) nanohybrids. The loading of Ppy in K-Bi was confirmed by thermogravimetric analysis while the formation of organic– inorganic hybrid was confirmed by infrared spectroscopy. K-Bi revealed a band gap of 2.8 eV while for the nanohybrids it was found to be ranging between 2.4 and 1.6 eV. X-ray diffraction studies confirmed partial intercalation of Ppy chains in the inter-layer space of K-Bi. High resolution transmission electron microscopy and scanning electron microscopy studies showed mixed morphology of K-Birnessite/Ppy nanohybrids. Rapid degradation of BPA was observed under visible irradiation in presence of K-Bi/Ppy nanohybrids and almost 90% degradation of 20 mg/L BPA solution was achieved within 120 min. The degradation was found to follow pseudo-first order kinetics and the degraded fragments were identified using liquid chromatography-mass spectrometry. Degradation pathway was proposed based on density-functional theory calculations of fukui index predicting the radical easy- attacking (f 0 ) and (f-) sites in BPA. © 2018 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. Keywords: Photocatalysis Degradation kinetics Manganese oxide Polypyrrole DFT calculations Introduction Bisphenol A (2, 2 bis (4-hydroxyphenyl) propane) (BPA) has been investigated to be one of the most hazardous organic pollutants commonly used in the production of polycarbonates and also as a stabilizer in several plastics products (Wang and Lim, 2010; Lan et al., 2001; Tan et al., 2017; Zhou et al., 2018; Chen et al., 2018). BPA is recognized as an endocrine disrupting chemical (EDC) and causes adverse effects on aquatic organisms even at low exposure levels (Hung et al., 2017). Several physical as well as chemical techniques have been adopted to remove BPA from aqueous solutions (Yamamoto et al., 2001; Watanabe et al., 2003; Torres et al., 2007; Ntsendwana et al., 2012). Among these, heteroge- neous photocatalytic degradation of organic pollutants is highly studied due to its high mineralization efficiency, low cost as well as operating ability under ambient conditions (Riaz et al., 2015a, 2015b). JOURNAL OF ENVIRONMENTAL SCIENCES 79 (2019) 161 – 173 ⁎ Corresponding author. E-mail: uriaz@jmi.ac.in. (Ufana Riaz). https://doi.org/10.1016/j.jes.2018.11.021 1001-0742 © 2018 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. Available online at www.sciencedirect.com ScienceDirect www.elsevier.com/locate/jes