Removal of Fluoride Ions from Drinking Water by Activated Alumina and Activated Charcoal

Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 1054-1059

J. Environ. Treat. Tech.

ISSN: 2309-1185

Journal web link: http://www.jett.dormaj.com

Removal of Fluoride Ions from Drinking Water by

Activated Alumina and Activated Charcoal

Habiba Lebrahimi *, Mohammed Fekhaoui , Abdelkabir Bellaouchou .

Department of Zoology and Animal Ecology, Laboratory of Zoology, Scientific Institute, Mohamed V University, Avenue Ibn Battouta, Agdal,

0090, Rabat, Morocco

Department of Toxicology, National Institute of Hygiene, 27, Avenue Ibn Batouta, 769 Agdal, Rabat, Morocco

Department of Chemistry, Faculty of Sciences Rabat, Mohamed V University, 4 Avenue Ibn Battouta, 1014 Agdal, Rabat, Morocco

Abstract

The pollution of drinking waters by ions fluorides caused by industrial and natural activities, causes major problems for human

health, what imposes to think seriously of the treatment of these waters. Experiments are carried out in the laboratory to remove fluoride

ions in water, based on the adsorption process by activated alumina and activated carbon with a change in different parameters

influencing the retention rate such as pH, amount of adsorbent and contact time. Good defluoridation requires a contact time between

0 min and 60 min with a retention rate of 53.51% and 67% for activated alumina, 50.27% and 56.35% for activated carbon. The

retention rate for 3g adsorbent is 56% for activated alumina and 18.91% for activated carbon, this value increases with increasing

adsorbent quantity for acid pH. According to these experiments the retention rate of fluoride ions by activated alumina is higher than

that of activated carbon, which makes activated alumina treatment the most responsive for the removal of fluoride ions in water. in this

work they try to find an appropriate method to eliminate the excess of ions fluorides in underground water after a study made on these

ions in waters of the region of Khouribga in Morocco as phosphaté region the presence of ions of which results points out fluoride with

a broad broadcasting of the illness of fluorosis to the population. According to tries made in the laboratory one there found that alumina

speeded up and activated charcoal is very efficient for this action.

Keywords: Fluoride, Activated alumina, Activated carbon, Water treatment, Defluoridation, Adsorption

is based on the adsorption technique on activated carbon and

Introduction¹

alumina, which are the most responsive, effective, very simple

and do not require much maintenance. Both elements are the

most used industrially because of their excellent

decontamination properties against the majority of pollutants.

Considerable efforts are made to ensure a better protection of

the environment of water resources. Scientific research is

increasingly oriented towards the selection of the most effective

means of depollution. Several methods of treatment of water

containing fluorine, mainly adsorption by activated alumina

and activated carbon, have given their effectiveness in

removing fluoride ions dissolved in water [7]. This process is

well suited to the elimination of fluoride ions with a need to

control the ions but the pH of the treated water need to be

control. The adsorption capacity depends on the specific

surface of the material, the nature of the adsorbent, and the

contact time. For our study one there chosen the treatment by

the adsorption by alumina speeded up and activated charcoal

seen that their fastness and their effectiveness according to

results found without forgotten availability of this two

Fluoride (F-) contamination in groundwater has been

recognized as one of the serious problems worldwide. Fluoride

is classified as one of the contaminants of water for human

consumption by the World Health Organization (WHO), in

addition to arsenic and nitrate, which cause large-scale health

problems [1]. The fluorine as most part of the chemical

elements (iron, manganese ...) effects of which their excess in

Drinking Water causes failure for water and environment [2].

The quality of waters of drink is an obligation for everybody

what obliges a strict treatment [3]. the classical techniques used

for the treatment of waters of drinks are several categories

among which in most cases the adsorption with activated

charcoal, alumina speeded up and loam, the techniques of haste,

physicochemical techniques (separation on membrane,

oxidation

/ discount) and other biological techniques

(biosorption, phytoextraction) [4]. The pollutions of

underground waters of the region of Khouribga are a strict

problem, because it causes an endemic illness to the population,

what makes think seriously of the treatment of waters intended

for human consumption. Everything results acquired from the

physicochemical analyses of underground water of the region

of khouribga are has norm except the content of fluorine which

was superior has norm in several wells of the region. [5].

The removal of fluoride ions from groundwater is done by

several techniques which differ from each other depending on

the removal percentage (efficiency) and treatment cost.

adsorbants in Morocco as developing country [8]. The

objective of fluoride removal meant the treatment of

contaminated water in order to bring down fluoride

concentration to acceptable limits. The defluoridation

techniques are generally classified into 2 classes, specifically

membrane and surface assimilation techniques. No study was

made in this sense in Morocco contrary has the ladder

international or they find many people work on this problem,

According to several studies [6], among these techniques, one

Corresponding author: Habiba Lebrahimi, Department of Zoology and Animal Ecology, Laboratory of Zoology, Scientific Institute,

Mohamed V University, Avenue Ibn Battouta, Agdal, 10090, Rabat, Morocco, +212762567494, zaidhabibalebrahimi@gmail.com.

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 1054-1059

the treatment of waters of which becomes an obligation in our

seen country has consumption there.

Materials and methods

.1 Generality

The adsorption of a substance by a solid is the more or less

irreversibly binding of the solute molecules in contact with the

surface of this solid without any chemical reaction between

them. This is a rapid phenomenon that results in a balance

between the substance adsorbed and the substance remaining in

solution. Balance depends on the concentration of the solute

and the surface of the adsorbent body. There are two types of

adsorption:

Physical adsorption: reversible, which does not modify the

chemical identity of the adsorbed molecules.

Chemical adsorption: irreversible, characterized by

chemical bonds between the adsorbate and specific adsorption

sites. This process is well adapted to the specific elimination of

fluorides but requires controlling the pH of the medium. The

adsorption capacity depends on the specific surface of the

material, the contact time, the pH and the initial fluoride

concentration. [9].

Water defluoridation studies using several adsorbents such

as aluminium hydroxide, activated carbon, and apatite and

activated alumina have been carried out with encouraging

results. [10]. For our study we used both activated alumina and

activated charcoal because of their efficiency in the treatment

as well as their cost and availability.

2 3

Activated alumina (Al O or aluminium oxide): To make

two adsorbents assets an elimination of the molecules of water

was made by calcination has a temperature of 500 °. the

technology used for the elimination of ions fluorides dissolved

in waters of drink consists has percale some water to charge in

fluorine on a bed of alumina speeded up allowing the retention

of these ions, the most answering of which he is and assures a

specific elimination of ions fluoride has strong

concentration.[11]. The presence of fluoride ions with high

levels in groundwater intended for human consumption

requires serious efforts to treat them. In fact there are several

treatment processes. Principle of adsorption: The principle of

adsorption treatment is to fix the pollutants on an absorbent

material. It is a separation process i.e. a simple transfer of mass

from the liquid phase to the solid phase by fixing on their

surface certain molecules, macromolecules and ions or certain

gases.

.2 Analytical method:

For our work, experiments were made in the laboratory for

Figure 1: Elimination of fluorine by activated alumina / activated

charcoal

the elimination of fluoride ions in the ground water by

adsorption processes through two products: activated carbon

and activated alumina (Al2O3 aluminium oxide). A solution

prepared by dissolving 150 mg of sodium fluoride NaF. Dried

in the oven for 3 hours, cooled in a desiccator in one liter of

distilled water, and kept in a plastic bottle. All experiments

were performed at ambient temperature of 27.1°C ± 2°C. Batch

sorption tests were performed to determine the effect of control

of related different parameters such as pH, contact time and

adsorbent quantity. (Figure 1).

The water samples taken were treated with activated carbon

and activated alumina (Al O aluminium oxide) after they are

2 3

activated at 500°C. The experimental protocol is to pass the

sample through two columns each one containing one of the

absorbents, by three batches depending on the pH, the quantity

of the absorbent, and the contact time.

st batch: to know the effect of the pH, the quantity of the

adsorbent 3g is fixed, the contact time is the time of the

filtration of a fixed volume of 50 ml of the prepared solution,

and the pH of 5 and 8 is changed, the pH is adjusted by HCl

(0.5 M) or NaOH (0.5M).

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 1054-1059

Figure 2: Flow chart of the working methodology

PO43->F->SO3->Fe(CN)64->CrO42->SO42->Fe(CN)53-

Cr2O72->I->Br->Cl->NO3->MnO4->ClO4-> S2-. It is

apparent that activated alumina adsorptive force for phosphate

anion is stronger than other anions, such as SO42- and Cl-, so

activated alumina adsorb phosphate anion in predominance.

[12].

Results and discussion

.1 Contact time

Contact time adsorption tests for activated alumina and

activated carbon show that the removal rate increases with

increasing time until a given point in time when a constant

value approaches that indicates the equilibrium point between

treated water and adsorbent. According to this experience, the

fluoride ion removal treatment procedure goes through three

phases: The 1st was before 30 min of contact where the

retention rate is relatively fast, 53.51% for activated alumina

and 50.27% for activated charcoal, this speed due to the affinity

of the adsorbent surface and the force of entrainment and

Figure 3: Measure of F- by the electrode specific

diffusion in the porous medium. The 2 is between 30 min and

0 min which consist of the migration of fluoride ions to the

rd batch: to study the contact time effect, the experiments

internal pores of the adsorbent, leading to high levels of

fluoride retention rate, recording 67% for activated alumina and

were performed by varying the contact time by 30, 60 and 120

and passing a 50 ml volume of the prepared solution over two

g columns of activated carbon and activated alumina for a pH

6.35% for activated carbon. The 3 phase when we exceed 60

min the retention rate is almost constant, reaching 69.46% for

activated alumina and 58.78% for activated carbon (Figure 4

and Figure. 5). According to these results they point out that the

percentage of the elimination of ions fluoride on alumina

speeded up and activated charcoal augments fast with the

increase of the time of contact especially for the first 60

minutes, of which beyond they note that the percentage of

elimination gone towards stability for two adsorbents seen the

occupation of the harbours of fixing of ions, therefore they can

fix the time of contact has 60 minutes until 90 minutes, what

points out that the time of contact has an effect on the

elimination of ions fluorides. The results found are in

agreement with those of BEN NASR et al 2014. Found for this

work concerning the elimination of fluoride ions by the

different treatment processes, also with the results found by fan

et al, which fixes the time necessary for a good retention of

these ions of less than 60 min.

of 6.1.

rd batch: this is to study the effect of the quantity of

adsorbents on the rate of elimination of fluoride ions in water,

whose experiments are done with different quantities of 3g, 6g

and 9g, using the same volume of 50 ml of the initial solution

for a fixed pH 6.1 (Figure 2). The determination of fluoride ions

is done before and after treatment with the specific electrode

and the rate of elimination of fluoride ions is calculated by the

following equation: (Figure 3).

R : (Ci-Ce / Ci)× 100

where, R is the removal efficiency of fluorinated compounds

(%), Ci is the initial concentration (mg/l) and Ce is the

equilibrium concentration (mg/l) [6]. The order of activated

alumina adsorptive force for anion in water is followed: OH-

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2020, Volume 8, Issue 3, Pages: 1054-1059

Figure 4: Retention rate % (activated alumina)

Figure 5: Retention rate % (activated charcoal)

Figure 6: Retention rate % (activated alumina)

Figure 7: Retention rate % (activated carbon)

.2 Effect of quantity of adsorbent

Tests of fluoride ions adsorption in water were carried out

The pH of the prepared water is 6.1, and in order to know

the effect of pH on the retention rate of fluoride ions, the pH is

adjusted by adding HCL 0.1 so that it becomes acid (pH 5) and

NaOH so that it becomes basic (pH 11).

by varying the quantity of adsorbent by 3g, 6g and 9g which

influences the retention rate according to the graphs below

(

Figure. 6 and Figure. 7). The results show that the retention rate

increases with raising the amounts of adsorbent from 56% to

3.37% for activated alumina and from 18% to 32.83% for

The results found after the determination of fluoride ions in

these waters for both cases, show that the retention rate in the

acid medium (pH=5) is 75.67% for activated alumina and

48.35% for activated carbon. However in the basic medium

(pH=8) we obtained a retention rate of 47.3% for activated

alumina and 41.35% for activated carbon (Figure. 8 and Figure.

9). Hence it appears that the pH of the medium considerably

influences the rate of fluoride retention in water. These results

are almost compatible with those found by Anis Ben nasr 2014

[6]. These results watch that the percentage of elimination of

ions fluoride for a sour water is superior that a basic water for

alumina speeded up and the opposite for activated charcoal

what points out that the percentage of fixing varies according

to nature da pH, they conclude therefore that the pH influences

fluorides in general on the elimination of ions according to the

chosen adsorbent.

activated carbon in the case of 6g of the absorbent. Whereas,

when the amount of absorbent is increased from 3g to 9g, we

obtained a retention rate of 82.7% and 45.67% respectively for

activated alumina and activated carbon (Figure. 6 and Figure. 7).

These found results watch which the percentage of elimination

of ions fluorides augments with the increase of the quantity of

adsorbent at the same time activated charcoal is for alumina

speeded up or, what points out that for a strong elimination of

these ions needs an important quantity of adsorbents. This

indicates that the rate of elimination of fluoride ions increases

with increasing adsorption surface. This is in agreement with

the results a obtained by BEN NASR et al 2014, who found a

retention rates of 96% and 89% in the case of absorbent’s

amounts of less than or equal to 15g/l-1.

.3 pH effect

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2020, Volume 8, Issue 3, Pages: 1054-1059

fluorosis caused in general by the consumption of waters rich

in fluorine, with which elimination of these ions become an

obligation, alumina speeded up and activated charcoal is the

most appropriate seen their effectiveness, their weak-willed

person expenses and their availability in our country especially

the region of khouribga. The quality of waters in the Khouribga

region is characterized by high levels of fluoride causing,

among others, dental fluorosis to the population of this region,

what requires tries to eliminate this excess of these fluoride

ions. The treatment of contaminated groundwater by fluoride is

made by several techniques, the adsorption, one among them,

is efficient and cost effective. In our case we have chosen the

treatment by two chemical elements, namely activated charcoal

and alumina speeded up to treat waters, which are most adapted

and economic. The obtained results show that the best rate of

retention has been recorded in the case of activated alumina

comparatively to activated carbon. Moreover we found that the

elimination of ions fluorides is influenced by different

parameters, especially the pH, time of contact and the quantity

of used adsorbent. Finally the acquired results show that the

adsorption on speeded up alumina and activated charcoal can

constitute an efficient technique for the elimination of the

fluorine.

Figure 8: Retention rate % (activated alumina)

Aknowledgment

I thank all personnel of the laboratory of hydrology have

the institute of hygiene of Rabat Morocco for their support, also

everything the persons that helped us has accomplish this

publication.

Ethical issue

They confirm that our publication is original.

Competing interests

The authors declare that there is no conflict of interest that

would prejudice the impartiality of this scientific work.

Figure 9: Retention rate % (activated carbon)

Authors’ contribution

Other results found by Srimurali et al 2008. [7] and

Bersillon et al 2006. [12, 13, 15] Suggest that the elimination

of ions fluoride is quick if we leave 10 min of contact between

alumina speeded up and the contaminated water. In the case of

All authors of this study have a complete contribution for

data collection, data analyses and manuscript writing.

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fekhaoui@israbat.ac.ma.

Mohammed Fekhaoui, Manager of the

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fekhaoui@israbat.ac.ma.

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