Chemical Engineering Journal 410 (2021) 128246 Available online 25 December 2020 1385-8947/© 2020 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej A CFD study of an annular pilot plant reactor for Paracetamol photo-Fenton degradation Cesar M. Venier a,d , Leandro O. Conte b,∗ , Monserrat Pérez-Moya c , Moisés Graells c , Norberto M. Nigro a , Orlando M. Alfano b a Centro de Investigación de Métodos Computacionales (CIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Universidad Nacional del Litoral (UNL), 3000 Santa Fe, Argentina b Instituto de Desarrollo Tecnológico para la Industria Química (INTEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Universidad Nacional del Litoral (UNL), 3000 Santa Fe, Argentina c Chemical Engineering Department, Universitat Politècnica de Catalunya, Escola d’Enginyeria de Barcelona Est (EEBE), 08019 Barcelona, Spain d Escuela de Ingeniería Mecánica, Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Universidad Nacional de Rosario, Rosario (UNR), 2000 Rosario, Argentina ARTICLE INFO Keywords: Photo-Fenton OpenFOAM Pilot-plant reactor Radiation model Paracetamol ABSTRACT This work studies in detail the photo-Fenton degradation process of Paracetamol (PCT) on an annular pilot- plant reactor using Computational Fluid Dynamics (CFD). A cylindrical lamp emission model was originally implemented over the structure of the OpenFOAM(R) platform and a multicomponent reaction mixture model was used to compute the temporal evolution of the different species at each point of the reactor. Once the proposed model was experimentally validated, the influence of different operating conditions (i.e. different strategies for hydrogen peroxide (H 2 O 2 ) dosage, use of low recirculation flow rates (Qr), and a completely uncovered lamp setup) was studied. The results of the analysis showed that a double addition of H 2 O 2 (50% before the tank and 50% before the reactor) significantly reduces the reaction times of the process. Moreover, the overall PCT degradation rate does not change when Qr is increased, thus allowing the system to be operated with a recirculation flow three times lower than that the one used in the experiments. Thereby, the developed model allows identifying the reaction conditions that maximize the overall PCT conversion, making efficient use of H 2 O 2 (main chemical reagent) and reducing the electrical energy consumption (recirculation flow) by operating the system under conditions present in large-scale photochemical reactors. 1. Introduction The production and consumption of pharmaceutical compounds have been increased considerably in the last years due to the growing use of the world’s population. Antibiotics, antipyretics and analgesics are the most widely used drugs. In particular, acetaminophen or parac- etamol (PCT) occupy the top of the list among the analgesics [1]. These pharmaceutical compounds, mainly produced from urban and industrial effluents, not properly treated in conventional plants, end up in the environment by different pathways [2–4]. As a consequence, these chemicals and their residues not only have negative impacts on the aquatic ecological systems but have also been detected frequently in drinking waters [5,6], affecting human health [7,8]. Therefore, it is absolutely necessary to develop reliable technologies capable of removing not only the PCT but also its metabolites/degradation prod- ucts from wastewater prior to being discharged into the environment. Advanced oxidation process (AOPs), are being intensively investigated ∗ Corresponding author. E-mail address: lconte@santafe-conicet.gov.ar (L.O. Conte). as a superior alternative to achieve this goal [9–11]. Here, the photo- Fenton process takes advantage due to the high removal efficiencies it shows to remove this type of pollutants, in addition to allowing the use of the sun as a source of energy for the process [12–15]. However, it is known that ‘‘traditional’’ photo-Fenton condition includes acidic medium which means an additional cost for pH adjustment. At this point, the use of iron chelates (such as iron citrate, ferrioxalate, EDDS, etc.) proved to be a surpassing alternative [16–18]. Also, there are several studies in the specific literature regarding the effect of organic and/or inorganic species when the photo-Fenton process is applied in real wastewater [19–21]. Nevertheless, it should be noted that all these topics have been studied using ideal reactor models. The efficient implementation of these AOPs involves the resolu- tion of multi-component, non-ideal reactor models, which consists of computing the spatial distribution of the reacting species and the https://doi.org/10.1016/j.cej.2020.128246 Received 3 July 2020; Received in revised form 20 November 2020; Accepted 18 December 2020