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The Adsorptive Removal of Fluoride from Aqueous Solution by Modified Sludge: Optimization Using Response Surface Methodology

1
Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang’an University, Xi’an 710054, China
2
Xi’an Center of Geological Survey, China Geological Survey, Xi’an 710054, China
3
School of Geography and Tourism, Shaanxi Normal University, Xi’an 710054, China
*
Author to whom correspondence should be addressed.
Int. J. Environ. Res. Public Health 2018, 15(4), 826; https://doi.org/10.3390/ijerph15040826
Received: 26 March 2018 / Revised: 14 April 2018 / Accepted: 14 April 2018 / Published: 23 April 2018
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Abstract

The sludge from the water supply plant was investigated to remove fluoride ions from the water. To improve the adsorption ability, the original sludge sample was treated with fuel oxidation, pyrolysis, hydrochloric acid, and sulphuric acid methods, and hydrochloric acid treatment improved the adsorption capacity of the sludge on the fluoride in water significantly, with a maximum adsorption capacity to 140 mg/kg. The adsorption experimental data was the well fitted pseudo-first-order model and the Langmuir isotherms model. SEM images and XRD patterns of the adsorbent were recorded to get a better insight into the adsorption process. The effect of three variables, hydrochloric acid treated sludge (HWS) dose, pH, and initial fluoride concentration were studied using a Box-Behnken statistical experimental design. The model of the adsorption and optimum conditions was investigated using the response surface methodology. The optimum removal efficiency of fluoride can reach 81.153% under the optimum condition: HWS dose of 14.10 g/L and pH value at 6.12. The effect of co-existing anions and the removal efficiency from the water were also studied. The results suggest that sludge from the water supply plant can be reused as a coagulant for the removal of fluoride from poor quality water. View Full-Text
Keywords: fluoride; response surface methodology; water supply plant sludge; adsorption fluoride; response surface methodology; water supply plant sludge; adsorption
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Li, Y.; Yang, S.; Jiang, Q.; Fang, J.; Wang, W.; Wang, Y. The Adsorptive Removal of Fluoride from Aqueous Solution by Modified Sludge: Optimization Using Response Surface Methodology. Int. J. Environ. Res. Public Health 2018, 15, 826.

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