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European Journal of Applied Sciences – Vol. 10, No. 4
Publication Date: August 25, 2022
DOI:10.14738/aivp.104.12671. Sedou, M., Mande, S. A., Sanou, Y., & Arouna, K. (2022). Fluoride Removal in Synthetic Drinking Water by Electrocoagulation Using
Aluminum Electrodes. European Journal of Applied Sciences, 10(4). 429-438.
Services for Science and Education – United Kingdom
Fluoride Removal in Synthetic Drinking Water by
Electrocoagulation Using Aluminum Electrodes
Moudassirou Sedou
Laboratory of Water Resources and Environmental
Engineering, University of Kara. Faculty of Sciences
and Technics, B.P. 404, Kara-Togo
Seyf-Laye Alfa-Sika Mande
Laboratory of Water Resources and Environmental
Engineering, University of Kara. Faculty of Sciences
and Technics, B.P. 404, Kara-Togo
Laboratory of Applied Hydrology and Environment
University of Lome, BP. 1515, Togo
Beijing Key Laboratory of Water Resources &
Environmental Engineering, China University of
Geosciences (Beijing), Beijing 100083, P.R. China
Yacouba Sanou
Laboratory of Water Resources and Environmental
Engineering, University of Kara. Faculty of Sciences
and Technics, B.P. 404, Kara-Togo
Laboratory of Analytical, Environmental and
Bio-Organic Chemistry, University Joseph KI-ZERBO
UFR/SEA, 03 BP 7021 Ouagadougou 03, Burkina Faso
Kadidja Arouna
Laboratory of Water Resources and Environmental
Engineering, University of Kara. Faculty of Sciences
and Technics, B.P. 404, Kara-Togo
ABSTRACT
Fluoride is recognized as an essential constituent in the human diet. Low fluoride
concentration could prevent dental problem while higher fluoride concentration
will cause dental and skeletal fluorosis. This study aimed to remove fluoride in
synthetic drinking water by electrochemical system. It had been performed at
laboratory scale using fluoride synthetic water. The process consisted to optimize
the fluoride removal in drinking water using the Aluminum electrodes. The effects
of operating conditions such as the initial ion fluoride concentration, current
density or intensity, contact time, and NaCl amount were studied. Experimental
results showed that with the initial concentration of 15 mg/L using the optimal
intensity (1.5 A), an admitted residual concentration (1.5 mg/L) was observed
during 45 min of electrolysis while maximum fluoride removal percentage of 100
% was achieved for 60 min. The variation of energy consumption from 1.18 to 22.35
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European Journal of Applied Sciences (EJAS) Vol. 10, Issue 4, August-2022
Services for Science and Education – United Kingdom
Wh showed that the electrocoagulation can be applied using photovoltaic energy
for fluoride treatment in drinking water.
Keywords: Aluminum, electrocoagulation, fluoride, removal efficiency, water treatment.
INTRODUCTION
Drinking water contamination by fluoride is a threat for human health. His presence in drinking
water originate especially from anthropogenic sources in addition to the dissolution of
minerals in rocks and sediments. Nearby the mining sites and industrialized areas, the
concentration values measured in water bodies for fluoride (1 - 4ppm) (Tanouayi et al., 2016)
are extremely higher than the values about 1.5 ppm (WHO, 2011). The mining areas of
Hahotoé-Kpogamé (phosphorite ore) contain high levels of fluoride which has induced illness
related to fluorosis among people living in the vicinity of mining and processing sites (Melila,
2013; Ouro-Sama et al., 2014; Tanouayi et al., 2016). However, recent studies revealed a high
prevalence of fluorosis in Hahotoé-Kpogamé mining areas about 45 % (Melila, 2013).
Moreover, there is no studies dealing with fluoride remediation in drinking water in Togo, a
developing country with several priority areas. Thus, it appears essential to find a low-cost
effective method for fluoride removal from drinking water sources in Togo.
Chemical coagulation-based treatment is the most common approach for treatment in drinking
water production (WHO, 2011). A range of methods including chemical coagulation has been
reported especially for the removal of arsenic and fluoride from aqueous solutions, these
methods being mainly reduction, ion-exchange, electrodialysis, electrochemical precipitation,
evaporation, solvent extraction, reverse osmosis, chemical precipitation and adsorption (Alfa- Sika Mande et al., 2009; Harisha et al., 2010; Jadhav et al., 2015; Ahoulé et al., 2015, WHO, 2011).
Most of these methods are not cost-effective and suffers drawbacks such as disposal of the
residual sludge which poses further problems for the environment (Jadhav et al., 2015; Shan et
al., 2019). One of these techniques, electrocoagulation, appears to provide one of the most
effective, low cost methods because of its simplicity of operation, easy handling and no risk of
dangerous by-products (Guzmán et al., 2016; Shan et al., 2019). Electrocoagulation (EC) is the
process using "sacrificial" anodes to form an active coagulant which is used to remove
pollutants by precipitation and flotation in situ. EC is a complex electrochemical process, which
includes chemical and physical processes involving many surface phenomena. The technology
sits at the intersection of three fundamental technologies: electrochemistry, coagulation, and
flotation (Holt et al. 2004).When a potential is applied to form an external power source, the
anode material will undergo oxidation, while the cathode will experience reduction or
reductive deposition of elemental metals. The aluminum electrodes generated ��!"(aq) ions
will immediately undergo further spontaneous reactions to produce the corresponding
hydroxides and/or polyhydroxydes. These hydroxide compounds have a high affinity for
dispersed particles as well as counter ions to cause coagulation (Zhu and al., 2007). It is
considered to be a complex process with a multitude of synergistic mechanisms contributing to
the treatment of pollution. (Holt et al., 2004) were able to identify three categories of
mechanisms in electrocoagulation: electrochemical phenomena, coagulation and
hydrodynamics.
The aim of this study is to decrease substantially the fluoride concentrations in synthetic
drinking water by electrocoagulation using aluminum electrodes. The influence of key
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Sedou, M., Mande, S. A., Sanou, Y., & Arouna, K. (2022). Fluoride Removal in Synthetic Drinking Water by Electrocoagulation Using Aluminum
Electrodes. European Journal of Applied Sciences, 10(4). 429-438.
URL: http://dx.doi.org/10.14738/aivp.104.12671
parameters such as, current density, initial concentration, electrolysis time and the Sodium
Chloride (NaCl) are investigated using this type of electrodes.
MATERIALS AND METHODS
Experimental device of electrocoagulation
The defluoridation of drinking water is studied using the electrocoagulation system with
aluminium electrode. The figure 1 show the experimental setup of electrocoagulation (EC)
study. The electrocoagulation unit consisted of a 0.4 L electrochemical reactor with ��/��
electrodes. The distance between electrodes set was 1 cm. The anode and cathode were both
flat aluminium electrodes of rectangular shape (15 cm × 4.7 cm × 1 mm). They were vertically
centred between the bottom of the reactor and the liquid level.
Figure 1: Experimental device of EC reactor at Laboratory Scale.
Fluoride removal experiments
Desired concentrations of fluoride solutions were obtained by dissolving a weight of sodium
fluoride into distilled water. The conductivity of the sample water was varied by adding sodium
chloride (NaCl). The electrochemical removal of fluoride was carried out in an electrolytic cell
of 400 mL volume. Two electrodes (anode and cathode) were positioned vertically and parallel
to each other. At the beginning of each run, 350 mL of synthetic fluoride wastewater (11.7 cm
of height) was fed in the reactor and 0.5 g/L NaCl solution as electrolyte was added to increase
the conductivity of solution. The intensity of current was adjusted from 0.75 A, 1 A to 1.5 A,
corresponding to a current density between 13.64 and 27.28 mA/cm2 using a digital DC power
supply. Fluoride removal experiments were carried out with Aluminum electrodes electrode as
anode and cathode. The electrolysis time was performed during 60 min and the treated solution
was collected each 10 minutes. The electrocoagulated water samples were then filtered to
remove the flocs generated during the electrocoagulation process to be analyzed using UV-Vis
spectrophotometer (DIV-UV5600).
Energy consumption (E) expressed in Wh was calculated as follow:
E = Voltage (V) x Current intensity (A) x Time (h) (6)