Contents lists available at ScienceDirect Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece Photocatalytic degradation of atrazine in aqueous solution using hyperbranched polyethyleneimine templated morphologies of BiVO 4 fused with Bi 2 O 3 Lwazi Charles Mahlalela a , Cintia Casado b , Javier Marugán b , Santiago Septien c , Thabile Ndlovu d , Langelihle Nsikayezwe Dlamini a, * a Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Doornfontein, Johannesburg, 2028, South Africa b Department of Chemical and Environmental Technology, ESCET, Universidad Rey Juan Carlos, C/Tulipán s/n, 28933 Móstoles, Madrid, Spain c Pollution Research Group, University of KwaZulu-Natal, Howard College Campus, Mazisi Kunene Road, Durban 4041, South Africa d Department of Chemistry, University of Eswatini, Kwaluseni Campus, Private Bag 4, Kwaluseni, Eswatini ARTICLEINFO Editor: Teik Thye Lim Keywords: Atrazine Photodegradation BiVO 4 heterojunctions Cyanuric acid ABSTRACT Conventional methods have been reported to fail to completely remove contaminants of emerging concern (CECs) during wastewater treatment. Thus, new methods are required to improve wastewater treatment to completely remove the CECs from water. In this paper, we present the degradation of atrazine in aqueous solution using heterojunctions of BiVO 4 and Bi 2 O 3 that were synthesized from diferent morphologies of BiVO 4 (truncated octahedron, plate-like, and platelet-like). The nanoparticles (NPs) were characterized using a scan- ning electron microscope, X-ray difraction, UV–vis difuse refectance spectroscopy, photoluminescence spec- troscopy, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. It was observed that the heterojunctions were successfully synthesized and the observed morphologies for the BiVO 4 were truncated octahedron, plate-like and platelet-like. The most efective heterojunction in the removal of atrazine was 0.5NaCl-BiVO 4 -Bi 2 O 3 . The 0.15HPEI-0.5NaCl-BiVO 4 -Bi 2 O 3 had a reduced reaction rate compared to 0.5NaCl- BiVO 4 -Bi 2 O 3 , even though characterization showed that it was expected to be the most efective of all the NPs. The degradation of atrazine proceeded through dehalogenation, followed by the dealkylation and further dea- mination into cyanuric acid, a stable and less toxic compound. Data from LCMS/MS showed the formation of hydroxyatrazine, desethylhydroxyatrazine, and ammeline as intermediates. The degradation of several con- centrations of atrazine revealed that the heterojunction efciently removed > 90 % of atrazine. 1. Introduction Recalcitrant compounds that were undetectable in water can now be identifed due to the advancement of analytical techniques that permit the analysis of chemical compounds at extremely minute con- centrations. Some of these compounds have been classifed as com- pounds of emerging concern (CECs) and they include pharmaceutical products, personal care products, and pesticides [1,2]. Even though these CECs are detected in low concentrations, they possess the po- tential to be toxic and their long-term efects are relatively unknown as they remain unmonitored in the environment. Contaminants of emer- ging concern are defned as pollutants that were previously unknown or unrecognized, whose presence in the environment is not necessarily new, but concerns about their possible consequences is now known. These pollutants may have properties of altering the hormonal balance of the endocrine system of an organism [3]. Therefore, there is a need to develop methods that remove the CECs from surface water, ground- water, and wastewater treatment plants. Conventionally, these pollu- tants are removed from wastewater treatment plants through physical, biological, or chemical methods such as chlorination that do not com- pletely remove them, thus they fnd their way into the environment and/or drinking water [4]. An LCMS/MS-based survey done by Odendaal et al., 2015 [1], fo- cused on mapping CECs in drinking water of major cities in South Africa, and atrazine, a chemical employed in agriculture, was among the detected CECs. Its occurrence was mainly seasonal dependent at all sampling sites. The seasonal occurrence percentage of atrazine in the surveyed major cities of South Africa was 86 %, 71 %, 29 %, and 57 % https://doi.org/10.1016/j.jece.2020.104215 Received 21 April 2020; Received in revised form 20 June 2020; Accepted 23 June 2020 ⁎ Corresponding author. E-mail address: lndlamini@uj.ac.za (L.N. Dlamini). Journal of Environmental Chemical Engineering 8 (2020) 104215 Available online 25 June 2020 2213-3437/ © 2020 Elsevier Ltd. All rights reserved. T