Predictive equations for the defluoridation by electrocoagulation technique using bipolar aluminum electrodes in the absence and presence of additives: a multivariate study

Abstract

The adverse public health problem due to the fluoride that is found in drinking water and waste water is of great concern. In the present work, the effect of different variables on the defluoridation by electrocoagulation (EC) process was studied. The variables were analar and commercial sodium fluoride solutions, different fluoride concentrations, pH of solution, temperature, speed of agitation, electrode spacing, type of comprising water, electrolyte additives (NaCl, KCl, NH4Cl, and CH3COONH4), and mono and bipolar configurations. The present data indicated that the time required to reach the highest % extractions for the different concentrations of fluoride solutions (57.90, 42.30, 29.0, 21.50, 11.60, and 6.44 mg/L) was 5–15 min. Among the studied variables that significantly affected the maximum defluoridation efficiency, the type of comprised water was the only variable that did not pose observable effect. Statistically, a multivariate study was applied to get a set of predictive multiple regression equations, those were under constant and variable conditions of the fluoride removal process. Interestingly, these equations significantly represented the EC defluoridation technique under the studied variables. Due to the high economic value, the low applicable energy, as well as the saving of time that belong to the process of fluoride removal by EC, it is advisable to use the predictive equations for the EC defluoridation of different waters and wastewaters under the same conditions .