Taguchi’s optimization technique for water deflouridation through electrocoagulation

Abstract

Excess fluoride in drinking water is posing serious health concern to humankind. Electrocoagulation is an emerging technique for water defluoridation, and recent research is focused on the optimization of process variables for achieving maximum fluoride removal. As such, the Taguchi optimization technique is adopted to arrive at optimum values process parameters which can provide maximum fluoride removal with more accuracy and fewer experimental runs. In the present research a laboratory-scale batch EC reactor with four aluminum electrodes (98% pure) connected to a DC supply for a wide range of fluoride concentrations which were not studied in earlier researches. Taguchi’s L 16 orthogonal array was applied for optimization of the process variable It revealed maximum efficiency of 86.67% for defluoridation at optimum conditions of process variables with pH: 6 ± 0.1, initial adsorbate concentration: 5 mg/L, EC time: 45 min, voltage: 25 V, and IED: 2 cm. The percentage contribution of process variables was obtained by ANOVA in descending order as initial adsorbate concentration (45.31%) > pH (33.83%) > voltage (13.68%) > EC time (4.2%) > IED (2.98%). Freundlich isotherm and second-order kinetic models were found to be the best suitable for water defluoridation using the EC process. FTIR and XRD analysis for EC sludge also confirmed the fluoride sorption onto A l ( O H ) 3 flocs. The electrode consumption of 0.263 kg/ m 3 , and total operational cost of USD 0.6004/ m 3 were estimated for water defluoridation using the EC process.