Less energy and aluminum electrode consumption for fluoride removal using electrocoagulation process: optimization by one-way ANOVA analysis and experimental design

This study has two main objectives. First, an evaluation of the effects of five operating parameters namely current density (CD), electrolysis time (t(e)), pH, conductivity (sigma(i)) and stirring speed (SS) on the fluoride removal by electrocoagulation (EC) was conducted through one-way analysis of variance (ANOVA) strategy. Two more performance indicators namely energy consumption and loss of electro-dissolved aluminum electrode were considered. Second, development of three regression models to model and to determine the optimal conditions for electrochemical fluoride reduction process. To this end, EC experiments were carried in batch mode using stirred reactor with Al-Al monopolar configuration. One-way ANOVA results confirm that CD, t(e), pH, sigma(i) and SS have significant effects on reactor performance to reduce fluoride. Multiple regression analysis method demonstrates the reliability of the three developed model to predict the outcomes with respective R-2 values of 0.9879, 0.9949 and 0.9813 for fluoride removal efficiency, energy consumption and loss of electrode, respectively. Thus, EC can effectively bring down the fluoride concentration below permissible limits (1.4 mg center dot L-1) under the optimal conditions. The later are reached when the reactor is stirred at a speed of 102 rpm and the electrochemical cell is operating under a current density of 40.76 A center dot m(-2) for an electrolysis time of 23.38 min and the solution pH is adjusted to 7.17 and a conductivity of 2,374 mu S center dot cm(-1). These conditions generate a low energy consumption (54.58 Wh center dot m(-3)) and electrode loss equal to 25.51 x 10(-3)%.