Fluoride removal from synthetic groundwater by electrocoagulation process: parametric and energy evaluation

Abstract

This study investigates the effect of several parameters on the electrocoagulation process has been studied in order to optimize the evolution of the fluoride removal percentage and the energy consumption. Optimum experimental conditions of fluoride removal were determined as: pH i = 6, J = 0.27 mA/cm 2 , t EC = 30 min, [NaCl] = 0.5 g/L, d i = 1 cm, S/V = 7.2 m-1 and Stirring speed = 300 rpm with two aluminum electrodes. These operating conditions are allowed to achieve fluoride removal of over 85% in a relatively short operating time with low energy consumption (0.0396 kWh/m 3). The results fitted with the Langmuir and Freundlich equations showed that fluoride removal was achieved by a monolayer adsorption, with a finite number of identical sites. To study the rate-limiting step, the kinetic data of fluoride were analyzed using first-order and second-order kinetic models. Under optimal conditions with 10 and 20 min treatment, fluoride was completely removed for initial concentration of 3 and 6 mg/L respectively. Moreover, for fluoride initial concentration of 10 mg/L, it is possible to reach a residual concentration under the limit recommended by WHO for fluoride concentration in drinking water (1.5 mg/L) with lowest consumption of electricity.

Electrocoagulation as a Promising Defluoridation Technology from Water: A Review of State of the Art of Removal Mechanisms and Performance Trends

“…where k 2 is the pseudo-first-order reaction rate constant. The data obtained for the adsorption of fluoride ions onto aluminium hydroxide flocs generated in the EC process satisfactorily agree with both the pseudo-first-order kinetics [41,69] and the pseudo second-order kinetics [44,58,61]. The defluoridation rates derived from the pseudo-order kinetics are dependent on the reaction conditions.…”

“…It is worth mentioning that adsorption taking place substitution of hydroxide groups present in Al n (OH) 3n flocs by the fluoride ions is the most prevalent fluoride removal mechanism for the EC using aluminium anodes [36,41,42,44,[46][47][48][50][51][52][53]55,56,[60][61][62][63][64][65][66][67]. Coprecipitation of fluoride and hydroxide ions with aluminium ions to produce a precipitate, Al n F m (OH) 3n−m is another mechanism occurring together with the adso-rption [36,42,44,[46][47][48]50,53,55,56,68].…”

“…The techno-economic analysis determines the cost-effectiveness of a treatment method. In the literature, several studies have incorporated a techno-economic analysis of fluoride removal from water by electrocoagulation technology [41,42,44,48,61,62,67,77,80,83]. To summarize, there are two types of costs that need to be considered when conducting a techno-economic analysis-capital and operating costs.…”

Comparison of Water Defluoridation Using Different Techniques

“…e results of a study revealed that electrodialysis technique could remove 50-60% of fluoride within 6 min [35]. One study showed that the fluoride removal efficiency of electrodialysis was from 50% to 90% [36]. Another study claimed that the removal rate of fluoride from drinking water by electrodialysis method was 92% [37].…”

“…In a study by Missaoui on EC treatment for fluoride removal from brackish water, the removal efficiency up to 52% was achieved under optimal status [67]. e study by Chibania et al reported the fluoride removal of over 85% in 20 min using EC technique [36]. One study indicated that electrochemical technique for defluoridation has shown a good yield for the removal of fluoride and aluminum concurrently using aluminum electrodes under 230 V DC [68].…”