Contents lists available at ScienceDirect Applied Clay Science journal homepage: www.elsevier.com/locate/clay Research paper Removal of dyes by a new nano–TiO 2 ultrafiltration membrane deposited on low-cost support prepared from natural Moroccan bentonite Abdelmjid Bouazizi a,⁎ , Majda Breida a , Brahim Achiou a , Mohamed Ouammou a , José Ignacio Calvo b , Abdelah Aaddane a , Saad Alami Younssi a a Laboratory of Materials Membranes and Environment, Chemistry Department, Faculty of Sciences and Technologies, University of Hassan II, Mohammedia, Casablanca, Morocco b SMAP (Surfaces and Porous Materials Group), Applied Physics Department, ETSIIAA, University of Valladolid, Palencia, Spain ARTICLE INFO Keywords: Moroccan bentonite Ceramic membrane Ultrafiltration Dye removal ABSTRACT This paper reports the preparation and characterization of a low-cost nano-TiO 2 ultrafiltration membrane de- posited on a bentonite support. The ultrafiltration layer was obtained by dip-coating process using nano-TiO 2 , followed by sintering at 750 °C. Environmental Scanning Electron Microscope (ESEM) analysis of prepared ul- trafiltration membrane showed that the deposited layer is homogeneous and shows a good adhesion on the support presenting a mean thickness of 4 ± 0.2 μm. The average pore diameter and water permeability of the obtained membrane are respectively 10 ± 0.5 nm and 16.08 L/h m 2 bar. The membrane performance was evaluated by filtration of three different dyes: two anionic (Direct red 80 and Acid orange 74) and a cationic one (Methylene blue). Effect of feed pH and dyes concentration on membrane rejection was investigated at a pressure of 4 bar. The experimental filtration results showed that rejection of Direct Red 80, Acid Orange 74 and Methylene Blue achieved maximum values of 98%, 85% and 94% respectively, depending on filtration condi- tions and each dye characteristics. 1. Introduction Safe water supply and environmental protection of water reserves have become two major preoccupations for many countries. Currently, many regions in Morocco, rest of Maghreb and most of Mediterranean countries are experiencing a problem of water shortage (Barrouk et al., 2015). This lack of water has been aggravated by the irrational use of natural resources and the rapid industrialization of the exposed areas. Given the gravity of the problem, it is necessary to consider adequate solutions to solve it. Textile, paper and plastic industries have often rejected colored wastewater without previous treatment. On the other hand, most of the dyes used in the textile industries are stable and resistible to ultraviolet light (they are not degraded due to sun rays attack) as well they are not biodegradable (Saffaj et al., 2004). They are also impervious to aerobic digestion, making these dyes long term water pollutants. To minimize the risk of environmental pollution, it becomes necessary to treat dye effluents before discharging them into water streams (Baraka et al., 2014). Several physicochemical techniques have been used to treat these dye effluents eliminating their contaminants, including solicitation, sedimentation, impaction, interception, adhesion, chemical adsorption, physical adsorption, flocculation and biological growth (Chinoune et al., 2016; Luo and Nguyen, 2017; Shi et al., 2006). Membrane technology has shown potentiality in the separation of dyes by microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF) (Jana et al., 2010; Aouni et al., 2012; Liu et al., 2017) and it is increasingly used in industrial processes such as water treatment. Therefore, the use of membrane technology could replace or at least minimize in a short future the conventional separation and purification techniques in many industrial processes, thus reducing the whole amount of energy being consumed (Seffaj et al., 2005). In recent years, industrial applications of porous ceramic mem- branes have attracted more and more the attention of scientific com- munity. This interest is due to their numerous benefits such as better thermal, chemical and mechanical resistance and controllable micro- structure (Ezziane et al., 2010). However, the use of composite ceramic membranes for wastewater treatment is still limited due to the high price of ceramic membranes. Looking for the economic feasibility of the use of membranes in many wastewater recovery applications, the development of low-cost ceramic membranes based on natural materials and some other waste http://dx.doi.org/10.1016/j.clay.2017.08.019 Received 30 May 2017; Received in revised form 19 August 2017; Accepted 21 August 2017 ⁎ Corresponding author. E-mail address: abdelmjidbouazizi@gmail.com (A. Bouazizi). Applied Clay Science xxx (xxxx) xxx–xxx 0169-1317/ Published by Elsevier B.V. Please cite this article as: Bouazizi, A., Applied Clay Science (2017), http://dx.doi.org/10.1016/j.clay.2017.08.019