Int. J. Environment and Waste Management, Vol. 16, No. 3, 2015
Comparing efficiency of bone char, cone char and cone active carbon in removal of fluoride from source water Mohamad Noorisepehr Department of Environmental Health Engineering, Alborz University of Medical Sciences, Tehran, Iran Email:
[email protected]
Mohamad Mortazavy and Jaseb Zhangane Department of Environmental Health Engineering, Persian Gulf & Oman Sea Ecological Research Institute, Islamic Azad University, Bandar Abbas Branch, Iran Email:
[email protected] Email:
[email protected]
Hasti Daraei* Department of Environmental Health Engineering, Shahid Beheshti University of Medical Sciences, Tehran, Iran Email:
[email protected] *Corresponding author Abstract: In this study, bone char, cone char and cone active carbon due to being cheaper than commercial active carbon for removing fluoride from water was investigated. The effect of parameters such as pH, contact time and initial fluoride concentration were examined. Excel, SPSS software, ANOVA and t-test were used for data analysis. The direct experimental findings showed that efficiency rate of different adsorbents for concentration of 8 mg/L is noticeably different (p < 0.05), also for 6 mg/L concentration, the remarkable difference just reveals in active carbon and cone columns but it did not show any difference with bone char column (p < 0.05). The statistical result showed although the active carbon efficiency in 4, 6 and 8 mg/L has no different, it is significant for bone coal and cone (p < 0.05). It means the fluoride removal ability decrease for concentration more than 6 mg/L in bone coal and cone, but not in active carbon (p < 0.05). The results showed that these adsorbents are convenient and cheap absorbent for fluoride removal. Keywords: fluoride; bone char; active carbon. Reference to this paper should be made as follows: Noorisepehr, M., Mortazavy, M., Zhangane, J. and Daraei, H. (2015) ‘Comparing efficiency of bone char, cone char and cone active carbon in removal of fluoride from source water’, Int. J. Environment and Waste Management, Vol. 16, No. 3, pp.275–279. Copyright © 2015 Inderscience Enterprises Ltd.
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M. Noorisepehr et al. Biographical notes: Mohamad Noorisepehr is an Associate Professor at School of Alborz University of Medical Sciences. The main topic of his research was wastewater treatment and biotechnology. Mohamad Mortazavy is an Assistant Professor at the Faculty of Environment Islamic Azad University Bandar Abbas Branch and he is a researcher in the environment field. Jaseb Zanganeh received his MSc degree from the Faculty of Environment Islamic Azad University Bandar Abbas Branch and he is a researcher in the environment field. Hasti Daraei is a Lecturer at the College of Public Health, Shahid Beheshti University of Medical Sciences. Her research interests are in the field of biosorption process, water and wastewater treatment, nutrient removal and wastewater treatment plant design. She has published more than ten papers in the fields of water and wastewater quality and treatment.
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Introduction
Fluoride and its compounds constitute 0.08% of the earth’s crust (Malakootian et al., 2011). It compound is one of the important elements for safety body and teeth. According to The WHO guideline, concentration of fluoride in drinking water is 1.5 mg/l (Thakre et al., 2010). If fluoride value in water drinking was too high (>1.5 mg/L) its compound causes skeletal and dental disease (Shen et al., 2003). There are many methods for removal of fluoride such as adsorption (using resins, clays), electrodialysis, precipitation, ion exchange and membrane separation (Waheed et al., 2009). The studies showed that adsorption process is one the current and appropriate method for fluoride removal. Char is one of the materials that are used as a sorbent for this aim. During recent decades many studies were done about fluoride and other pollutants removal by using cheap and accessible sorbent materials. In this study, cone char (CC), bone char (BC) and cone active carbon (CAC) which are waste product and low cost material were used as a sorbent for fluoride removal (Hamdi and Srasra, 2007). Also, the used activated carbon was prepared by application of a chemical-thermal process from cone. The researches show that char of these materials are good and satisfactory for selectivity sorption for ion removal (Ma et al., 2008). The purpose of the research is to study the proficiency and comparison of these materials in fluoride removal from aqueous solution. The effects of several parameters such as the types of the sorbent, pH and the initial fluorine ion concentration were evaluated.
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Materials and methods
2.1 Preparation of sorbent In this study three sorbent including BC, CC and CAC were used for fluoride removal. The sorbent used in this research was obtained from cattle bone and cone and active carbon was prepared from these materials. The BC was obtained from cattle bone. First,
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the fats was reduced from the bone and dried at 100–120°C. Then these materials were crushed and milled and finally sorbent was achieved with 0.3 cm size. Also, the cone washed several times with distilled water and dried in an oven at 100–120°C for moisture removal. Then, the cone was crushed and placed in ZnCl2 and activated in 800–1,100°C. After milling, the particles sieved between 0.5–1 mm.
2.2 Adsorption experiments In this study, column sorbent was used for fluoride removal. Below section of column was filled by glasswool and sorbent materials by certain weight strewed in this column. Also for minimisation in sorbent materials stretching and vacant spaces removal, the sorbent washed several times with distilled water and distilled water was passed through this column for several hours. A stock fluoride solution was obtained by dissolving 1.105 mg NaF (Merck Germany) in one litre of distilled water. Removal of fluoride from water using CC, BC and CAC were examined by various parameters such as: pH (6.5, 7.5 and 8.5), contact time (30, 60 and 120 minute) and concentration of fluoride (4.2, 6.5 and 8 mg/L), mass of sorbent 50 g. Finally, the concentration of residual fluoride in the solution was measured using spectrophotometer equipment at 570 nm.
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Results and discussion
3.1 Effect of pH Figure 1 shows the fluoride removal by CAC, CC and BC at varying the pH of solution from 6.5 to 8.5. According to result the maximum removal was obtained at pH 7.5. Also, the result shows that the CAC is more effective than CC and BC for removal of fluoride. This is due to the creation of weakly ionised hydrofluoric acid in acidic conditions (Daraei et al., 2014). Statistical evaluation shows that there is no significant relationship between varying pH (6.5, 7.5 and 8.5) and removal for three columns sorbent. It shows that pH would not be considered as a factor in the increase or decrease efficiency. For these results it can be concluded that the relationship between pH and removal efficiency is not direct correlation. Effect of pH on the removal of fluoride by AC, CC and BC Removal Efficiency (%)
Figure 1
80 75 70 65 60 55 50 45 40
active carbon cone char (0.5-1mm) bone char (0.5-1mm) 5
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7 pH
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Notes: Initial fluoride concentration: 4 mg/L, contact time: 30 min.
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3.2 Effect of contact time The results of different contact time are presented in Figure 2. It is definite from the figure that the efficiency increased with increasing contact time from 30 to 60 minute. Also, the result shows that the CAC is more effective than other materials in this study. Effect of contact time on the fluoride removal efficiency with CAC, CC and BC Removal Efficiency (%)
Figure 2
78 75 72 active carbon cone char (0.5-1mm) bone char (0.5-1mm)
69 66 63 60 0
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Time (h)
Notes: Fluoride concentration: 4 mg/L, pH: 7.5
3.3 Effect of initial concentration The results in Figure 3 indicate that increase in removal of fluoride was not substantial changes with increase in initial fluoride concentration of 4.2 mg/L to 8 mg/L on the CAC and CC (expect of BC). The statistics analysis shows the removal efficiency of different columns for concentration of 8 mg/l is noticeably different (p < 0.05), although for 6.2 mg/l concentration, the remarkable difference just reveals in CAC and CC column but it did not show any different with BC column (p > 0.05). Also for 4.2 mg/L concentration the statistics analysis shows the fluoride residual of CAC and CC columns is significant different. But for the fluoride residual in CAC and CC column or BC and CC column is not significant different (p > 0.05). The maximum sorption in high concentration can be credited to availability of more phenoxide ions in the solution (Daraei et al., 2013a). This suggests that whatever the fluoride concentration increase, the columns efficiency will be different. Figure 3
Effect of initial concentration on fluoride uptake with CAC, CC and BC Fluoride residual (mg/L)
3 2.5 2 1.5
active carbon
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cone char (0.5-1mm)
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bone char (0.5-1mm)
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initial fluoride concentration (mg/L)
Notes: Fluoride concentration: 4.2, 6.5 and 8 mg/L, pH: 7.5, contact time: 60 min.
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3.4 Effect of sorbent The statistically result showed that the CAC efficiency in 4.2, 6.5 and 8 mg/L concentrations has no difference, although it is significant for BC and CC (p < 0.05). It means that the fluoride removal ability decrease for concentration more than 6 mg/l in BC and CC, but not in CAC (p < 0.05). The results show that removal efficiency in various concentrations was significant difference for BC column. This indicated that removal efficiency was difference for all the fluoride concentration (4.2, 6.5, 8 mg/L). Also, according to result removal efficiency for low fluoride concentrations (4.2 and 6.5 mg/L) in CC column was not significant difference. But, in high concentration (6 and 8 mg/L) for removal efficiency in this column was significant difference. The high efficiency with increasing time is due to attraction of active functional groups towards fluoride, which leads to stronger surface binding (Daraei et al., 2013b).
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Conclusions
The results of this study showed that synthesised sorbents was operative for the extra fluoride removal in water. According to the results, at optimum conditions was observed the BC column had highest removal efficiency then CC and CAC.
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