Abstract-The batch study process was adopted to study the defluoridation of water using alum impregnated on brick powder. Different adsorption parameters, viz. effect of pH, effect of dose and contact time were selected and their optimization was done for the study. Alum and brick, when used individually are effective materials to cause defluoridation of water. But both the materials have certain limitations. Comparison of adsorption by Alum impregnated brick powder was made with adsorption by brick powder. In the optimum condition of pH and dose of adsorbents, the percentage defluoridation from synthetic sample for Alum impregnated on brick powder was found to be 4.0-5.0 % higher than the defluoridation due to brick powder. The test was performed on synthetic water prepared by using public supply water. The water contained very little other impurities. Presence of other ions in synthetic water did not significantly affect the defluoridation efficiency of Alum impregnated brick powder. The optimum pH range for the material was found to be 6.0-8.0 and adsorption equilibrium was found to be 60 min. These conditions make it very suitable for use in drinking water treatment. Defluoridation capacity of Alum impregnated brick powder can be explained on the basis of the chemical interaction of fluoride with the metal oxides under suitable pH conditions. The adsorption process was found to follow first order rate mechanism as well as Langmuir isotherm. Index terms: Defluoridation; Adsorption; Brick powder (BP); Alum impregnated on brick powder (AIBP)

Abhas Jain

S K Singh

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ISSN: 2319-5967 
ISO 9001:2008 Certified 
International Journal of Engineering Science and Innovative Technology (IJESIT) 
  Volume 3, Issue 4, July 2014 
591 
 
Defluoridation of water using Alum 
impregnated brick powder and its comparison 
with brick powder 
Abhas Jain, S.K. Singh 
     Abstract- The batch study process was adopted to study the defluoridation of water using alum impregnated on brick 
powder. Different adsorption parameters, viz. effect of pH, effect of dose and contact time were selected and their 
optimization was done for the study. Alum and brick, when used individually are effective materials to cause 
defluoridation of water. But both the materials have certain limitations. Comparison of adsorption by Alum impregnated 
brick powder was made with adsorption by brick powder. In the optimum condition of pH and dose of adsorbents, the 
percentage defluoridation from synthetic sample for Alum impregnated on brick powder was found to be 4.0-5.0 % higher 
than the defluoridation due to brick powder. The test was performed on synthetic water prepared by using public supply 
water. The water contained very little other impurities. Presence of other ions in synthetic water did not significantly 
affect the defluoridation efficiency of Alum impregnated brick powder. The optimum pH range for the material was 
found to be 6.0–8.0 and adsorption equilibrium was found to be 60 min. These conditions make it very suitable for use in 
drinking water treatment. Defluoridation capacity of Alum impregnated brick powder can be explained on the basis of the 
chemical interaction of fluoride with the metal oxides under suitable pH conditions. The adsorption process was found to 
follow first order rate mechanism as well as Langmuir isotherm. 
    Index terms: Defluoridation; Adsorption; Brick powder (BP); Alum impregnated on brick powder (AIBP). 
I. INTRODUCTION 
Natural waters contain fluorides in varying amounts. Consumption of water that contains fluoride in a 
concentration of approximately 1 mg/liter is found to be effective against tooth decay. For the same reason, salts 
with Fluoride concentration are added to public water supplies which contain Fluoride less than the desired 
concentration. In some places, where Fluoride concentration in drinking water supply has been in the 
permissible limits, tooth decay has been found to be 65% less than in communities with less or zero Fluoride 
[1].  Most un-fluoridated waters contain less than 0.3 mg/l fluoride. 
Excessive consumption of water with fluoride above 1.5 mg/L, however, may cause fluorosis. Fluorosis is 
condition in which the teeth become mottled, discolored, and pitted during their development. Skeletal fluorosis, 
characterized by increased bone density and abnormal bone growths, may result from long-term consumption of 
water containing 8 to 20 mg/l of fluoride [7]. The consumption of fluorides in excess of 20 mg/day over a period 
of 20 years or more could result in crippling fluorosis [11]. Dental health is of primary consideration for the 
control of fluoride in water. The USEPA National Interim Primary Drinking Water Standards have indicated 
that the allowable level of fluoride should not exceed 1.4 to 2.4 mg/l. This level is dependent upon the average 
maximum daily air temperature since the amount of water, and consequently the amount of fluoride ingested, is 
primarily influenced by the air temperature of the area. In general, most municipal water supplies contain less 
fluoride than the amount that is considered to be beneficial to dental health; however, many water supplies are 
found to exceed this limit. 
Rajasthan is located in the North-western part of India. It is more than 40% desert. Groundwater hence, contains 
fluoride above permissible levels. People in many parts of Rajasthan consume water with fluoride above 10 
mg/L. As a result people of all age groups have mottled teeth, skeletal fluorosis, painful and restricted joint, 
deformities in limbs and hunch back. Providing safe drinking water in interior parts of has been a challenge 
since the beginning. Efforts have been taken to avenge the problem. But most of the rural people still do not 
have access to safe drinking water [1]. 
Concern about elevated fluoride levels in drinking water is not based so much on acute toxicity effects, but 
rather on the long-term exposure to low levels of fluoride. In Rajasthan, a number of projects have been carried 
out on a variety of treatment methods for the removal of fluoride from potable water supplies. 
In adsorption method, different types of adsorbents have been used till date for defluoridation, e.g. activated 
alumina [13], coconut shell carbon [2], chemically activated carbon [8], bone charcoal [9], natural zeolites [10], 
burnt clay [6] and other low-cost adsorbents. The shortcomings of most of these methods are, low fluoride 
 
 
 
ISSN: 2319-5967 
ISO 9001:2008 Certified 
International Journal of Engineering Science and Innovative Technology (IJESIT) 
  Volume 3, Issue 4, July 2014 
592 
 
removal capacity, high operational and maintenance costs, lack of selectivity for fluoride, generation of large 
amount of sludge, undesirable after effects on water quality and complicated procedure involved in the 
treatment. The most commonly adopted method in India is the Nalgonda technique of community defluoridation 
which is based on precipitation process. It is very efficient and cost effective. The major limitations of Nalgonda 
technique are large amount of sludge production, daily addition of chemicals, least effective with water having 
high hardness and high total dissolved solids. Besides, it converts a large portion of ionic fluoride (67–87%) into 
soluble aluminum complex and practically, removes only a small portion of fluoride in the form of precipitate 
(18–33%) [5]. Therefore, this technique is erroneous. Residual aluminum ranging from 2.01 to 6.86 mg l−1 was 
also reported in Nalgonda technique [12], which is dangerous to human health as aluminum is a neurotoxin, 
concentration as low as 0.08 mg/L in drinking water may cause Alzheimer’s disease [3] and has strong 
carcinogenic properties. Studies have been carried out on brick powder [4]. In the present study, an attempt has 
been made for defluoridation of drinking water using Alum impregnated on brick powder (AIBP) as a new, 
feasible, suitable and low-cost adsorbent. 
II. MATERIALS AND METHODS 
Bricks utilized as adsorbents were manufactured in a brick kiln, situated near DTU Campus (New Delhi). These 
bricks were washed with distilled water, dried and ground properly to obtain fine powder. The brick powder was 
washed several times with distilled water till clear water was obtained and was dried in oven at 105 ◦C for 12 h. 
The dried material was sieved to separate less than 150 micro meter size of particles for the present study. Lab 
grade Alum used in the study was taken from laboratory and was used in powdered form. 0.5 grams of Alum 
was mixed in 1 liters of distilled water and the brick powder was put in the solution for 24 hours. The brick 
containing Alum was dried under sunlight. The comparison of the defluoridation capacity of AIBP was made 
with that of the BP. 
The stock solution of 100 mg/L fluoride was prepared by dissolving 221 mg of anhydrous NaF in 1 liter of 
distilled water. Test solution of 10 mg/L F
-
 concentration was prepared from fresh stock solution. All the 
experiments were carried out in 250 ml conical flasks with 100 ml test solution at room temperature (25
o
C). 
These flasks, along with test solution and adsorbent, were shaken in horizontal shaker to study the various 
control parameters. At the end of desired contact time, the conical flasks were removed from shaker and allowed 
to stand for 2 min for settling the adsorbent. Then, samples were filtered using Whatman no. 42 filter paper and 
filtrate was analyzed for residual fluoride concentration by using Fluoride meter as mentioned in the Standard 
Methods of Examination of Water and Wastewater. Batch study was conducted to determine the optimum 
conditions and to study the effect of pH, adsorbent dose and contact time on test solution. The effect of pH on 
fluoride was studied by adjusting the pH of test solution using 0.1 N HCl or 0.1 N NaOH on fixed quantity of 
adsorbent, while effect of adsorbent dose and contact time were studied by varying dose and contact time, 
respectively. Optimum conditions were selected for further studies. Water sample collected from a surface water 
source in New Delhi the details of which is given in the table 1. 
Table 1: Water Quality parameters of Public supply water used for experimental work. 
Parameter Value 
1. Total Dissolved Solids 230 mg/L 
2. Fluoride 0.3 mg/L 
3. Nitrate 4 mg/L 
4. Chloride 40 mg/L 
5. Total Hardness 120 /L 
 
 
 
 
 
ISSN: 2319-5967 
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III. RESULTS AND DISCUSSION 
A. Effect of pH 
The effect of pH on removal of fluoride was studied in the pH range of 2.0–11.0 and results are shown in Fig. 1  
 
PH played a major role in fluoride adsorption on AIBP. Comparison has been made with the results of Fluoride 
adsorption on BP. Maximum adsorption of fluoride was found to be 55.0–59% for AIBP in pH range between 
6.0 and 8.0. Percentage removal fell sharply as pH decreased below 6.0 and above 8.0. The lower adsorption 
efficiency of fluoride in acidic medium might be due to the formation of weakly ionized hydrofluoric acid, 
which reduces availability of free fluoride for adsorption. In alkaline conditions, lower adsorption may be due to 
the competition of OH− ions with F− ions for adsorption because of similarity in F− and OH− in charge and 
ionic radius [4]. Overall, Alum impregnated on brick powder showed 4-5 % increase in Fluoride adsorption. 
Alum makes the solution acidic and hence the final pH of the solution was on the left side of the pH scale. The 
pH dropped by 1-2 units in each sample. But maximum removal was obtained in pH range 6-8. pH 7 was 
adopted for further studies. 
 
Fig 1: Effect of pH on fluoride removal: Fluoride concentration is 10 mg/L, pH is maintained at 7 and contact 
time is 60 minutes. 
 
Fig 2: Initial and Final pH of the solution using Alum impregnated brick as the 
adsorbent. 
 
 
 
ISSN: 2319-5967 
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B. Effect of dose 
The effect of adsorbent dosage on adsorption of fluoride at pH 7.0, for Alum impregnated on brick powder for 
60 minutes, was studied. The results are presented as percentage removal of fluoride from water versus 
adsorbent dosage in Figure 3. The fluoride removal increased by 4-5 % in this case. Earlier obtained values were 
from 41 to 58 % for brick powder which increased to 46-64 % for alum impregnated on brick powder for 0.4–
4.4 g/100 ml dosages for both. However, it is hereby observed that after dosage of 1.6 and 2 g/100 ml there was 
no significant change in percentage removal of fluoride. It was due to the overlapping of active sites at higher 
dosage, thus, reducing the net surface area [9]. Hence, 2 grams per 100 mL was taken for further study.  
C. Effect of contact time 
As contact time was increased, initially, percentage removal also increased, but after some time, it gradually 
approached an almost constant value, denoting attainment of equilibrium. It was assumed that the equilibrium 
time is that at which curves appear nearly asymptotic to the time axis. In the present case, the equilibrium time 
was obtained at 60 min for both AIBP and BP. The changes in the rate of removal might be due to the fact that 
initially all adsorbent sites were vacant and the solute concentration gradient was high. Later, the fluoride uptake 
rate by adsorbent had decreased significantly, due to the decrease in number of adsorption sites. Decreased 
removal rate, particularly, towards the end of experiment, indicates the possible monolayer of fluoride ions on 
the outer surface, pores of both the adsorbents and pore diffusion onto inner surface of adsorbent particles 
through the film due to continuous shaking maintained during the experiment. [4] 
D. Adsorption isotherms 
The adsorption data were fitted to linearly transformed Langmuir and Freundlich isotherms. The linearized 
Langmuir isotherm is given by the Equation 1: 
1 1 1
e m m eq Q bQ C
 
   (1) 
By plotting graph between 1/qe and 1/Ce. From the values of the Langmuir and Freundlich isotherms, we see that 
R
2 
value is maximum for Langmuir isotherm which is 0.98. It can be concluded that the adsorption follow 
Langmuir isotherm and hence, assumptions by Langmuir shall be applicable. Langmuir isotherm assumes that 
each surface site can be singly occupied, There are no lateral interactions between adsorbed species, the 
enthalpy of adsorption is independent of surface coverage and energy of adsorption is constant thus creating 
homogeneity of energy on the surface (there is dynamic equilibrium between the adsorption and desorption 
processes).  
 
Fig 3: Effect of dose on fluoride removal: Fluoride concentration is 10 mg/L, pH is maintained at 7 
and contact time is 60 minutes. 
 
 
 
 
ISSN: 2319-5967 
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International Journal of Engineering Science and Innovative Technology (IJESIT) 
  Volume 3, Issue 4, July 2014 
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where Qm is the maximum adsorption for a complete monolayer coverage. In the equation b and Qm is obtained 
IV. CONCLUSIONS 
In the present study, a new adsorbent AIBP has been studied for removal of fluoride from synthetic water 
samples of different fluoride concentrations. The conclusions drawn from the above study are given below: 
(1) Adsorption of fluoride on AIBP from aqueous solution is found to be first order reaction and 
mechanism of fluoride removal on adsorbent was found to be complex. It follows the same mechanism 
as in case of defluoridation by using brick powder but with enhanced results. The surface adsorption as 
well as intra-particle diffusion contributes to the rate-determining step. 
(2) The optimum pH was found to be in range of 6.0–8.0 for maximum adsorption of fluoride, which 
makes it very suitable for use in drinking water treatment, especially in rural areas. Using lime to 
balance the slight acidic medium of the effluent water shall make it suitable for use. 
(3) Alum and brick when used individually remove fluoride but has certain limitations. When Alum 
impregnated bricks were used, better results were obtained with 4-5% increased fluoride removal. 
(4) Langmuir isotherm was followed in the process with correlation value 0f 0.98. 
 
ACKNOWLEDGEMENT 
I sincerely convey my thanks to my guide, Dr. S.K. Singh, HOD- Department of Environment Engineering, for 
all the support and guidance. I express my sincere gratitude to all the faculty of Environment Engineering 
Department. Their moral support and encouragement has played an important part in completion of my master’s 
degree. 
REFERENCES 
[1] Abhas Jain, S.K. Singh, “Prevalence of fluoride in ground water in Rajasthan state: Extent, contamination levels and 
mitigation”, Scientific Online, July, 2014 
[2] A.J. Arulanantham, T. Ram Krishna, N. Balasubramaniam, “Studies on fluoride removal by coconut shell carbon”, 
Indian J. Environ. Health 13, 531–536, 1992 
[3] A.M. Davison, “Water supply aluminum concentration: dialysis dementra and effect of reverse osmosis water 
treatment”, Lancet 9, 785–787, 1982 
[4] Asheesh Kumar Yadav, C.P. Kaushik, Anil Kumar Haritash, Ankur Kansal, Neetu Rani, “Defluoridation of 
groundwater using brick powder as an adsorbent”, Journal of Hazardous Materials B128 (2006) 289–293 
[5] B.V. Apparao, S. Meenakshi, G. Karthikayan, Nalgonada technique of defluoridation of water, Indian J. Environ. 
Protect. 10 (1990) 292–298. 
[6] G. Karthikeyan, M.N. Andal, S.G. Sundar, Defluoridation property of burnt clay, J. IWWA 31 (1999) 291. 
Fig 4: Plot of Langmuir isotherm for adsorption of Fluoride by Alum 
impregnated on brick powder 
 
 
 
ISSN: 2319-5967 
ISO 9001:2008 Certified 
International Journal of Engineering Science and Innovative Technology (IJESIT) 
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[7] Hodge, H.C., and Smith, F.A., “Some Public Health Aspects of Water Flouoridation, Fluoridation as a Public Measure,” 
A.A.A.S. (J.H. Shaw, Editor). Publ. No. 38, Washington, D.C. (1954). 
[8] K. Muthukumaran, N. Balasubramaniam, T.V. Ramakrishna, Removal of fluoride by chemically activated carbon, 
Indian J. Environ. Protect. 12 (1995) 514–517. 
[9] Killedar, D.J., D.S. Bhargava, Effect of stirring rate and temperature on fluoride removal by fishbone charcoal, Indian J. 
Environ. Health 35 (1993) 81–87. 
[10] P.K. Shrivastava, A. Deshmukh, Defluoridation of water with natural zeolite, J. Inst. Public Health Eng. (India) 14 
(1994) 11–14. 
[11] Roholm, K., “Fluoride Intoxication. A Clinical-Hygiene Sud,” H.K. Lewis and Co., Ltd., London (1937) 
[12] S.K. Gupta, A process for defluoridation of water by a filter bed using indigenous material, Indian J. Environ. Sci. 1 
(1997) 149–156. 
[13] S. Kumar, Studies on desorption of fluoride from activated alumina, Indian J. Environ. Protect. 16 (1995) 50–53. 
[14] Standard methods for the examination of water and wastewater. APHA, AWWA, WEF, APHA, AWWA, WEF, 
Washington, DC, 1995. 
 


Defluoridation of water using Alum impregnated brick powder and its comparison with brick powder

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Defluoridation of water using Alum impregnated brick powder and its comparison with brick powder

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