Decolourization of bromophenol blue by electrocoagulation process ABSTRACT This work concerns with electrocoagulation (EC) of bromophenol blue (BB) synthetic solutions using aluminum electrodes. First, some parameters such as BB concentration, solution conductivity, and inter- electrode distance were fixed with slow magnetic mixing of the solution during experiments varying the contact time from 5 to 90 min for different pH and applied voltage values. The optimal conditions for these experiments were found to be pH 10 and applied voltage 12 V (0.5 A, 143 A/m 2 ) for 95% removal of BB. Further, these optimal conditions were fixed and the other parameters such as BB solution concentration, solution conductivity, inter-electrode distance, and mixing velocity were varied. This research shows that EC process remains an interesting and valuable technology for textile dye wastewater treatment even though industrial scale applications must be realized to improve its wide acceptation. KEYWORDS: dye pollution, electrocoagulation, applied voltage vs. intensity curve, visible absorbance vs. pH curve, bromophenol blue (BB) 1. INTRODUCTION Contamination of water resources is a problem that is particularly acute today [1]. It is the result of the massive use of inorganic and organic chemical products in agricultural, urban, and industrial sectors [2]. The objective of this work is to study the effectiveness of an electrochemical process namely electrocoagulation (EC), which has already been shown effective for several water and wastewater treatment applications [3-16], in the removal of an acidic dye, bromophenol blue (BB), in synthetic solution. The experimental methodology adopted here concerns with the basic comprehension of the EC process. Also, the pH effect on the calibration curve and some key parameters influencing the EC process are examined. 2. MATERIALS AND METHODS 2.1. Experimental set-up The EC tests were performed using an experimental set-up shown in Fig. 1. In a 500 mL beaker filled with 500 mL of synthetic dye solution (distilled water + BB dye + NaCl), two (or four in some experiments) aluminum electrodes (20 cm length × 4 cm width) were immersed (active surface, S = 4 cm × 8.75 cm = 35 cm 2 ). The anode was connected to the positive pole and the cathode to the negative pole of the direct current power supply. The inter-electrode distance was fixed. 2.2. Cleaning of electrodes Before electrochemical tests, the Al electrodes were prepared as follows to avoid the presence of any impurity: (1) rinsed with distilled water and polished using abrasive paper, (2) cleaned in hydrochloric acid solution (20% w/w HCl) for 10 min, and (3) rinsed with distilled water. 1 Department of Chemical Engineering, University of Blida, P.O. Box 270, Blida 09000, Algeria. 2 Binladin Research Chair on Quality and Productivity Improvement in the Construction Industry, College of Engineering, University of Hail, P.O, Box 2440, Ha’il 81441, Saudi Arabia. Djamel Ghernaout 1,2, * , Abdulaziz Ibraheem Al-Ghonamy 2 , Sara Irki 1 , Amina Grini 1 , Mohamed Wahib Naceur 1 , Noureddine Ait Messaoudene 2 and Mohamed Aichouni 2 *Corresponding author: djamel_andalus@hotmail.com Trends in Chemical Engineering Vol. 15, 2014