Fluoride Removal from Water Using Aluminium Modified Activated Carbon Prepared from Khat Catha Edulis Stem
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Date
2021-07-10
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Addis Ababa University
Abstract
Fluoride is one of the most abundant elements found in Ethiopian groundwater and in many
other parts of the world, posing a significant threat to the regions’ groundwater supply. The
presence of fluoride above the set limit of 1.5 mg/L in drinking water consumed by humans has
resulted in a variety of physical health issues such as dental and skeletal fluorosis. In the
Ethiopian Rift Valley, nearly 8 million people drink fluoride-contaminated water. The same
problem has been seen in other regions such as the Kenyan and Tanzanian Rift Valleys. The
current study describes the preparation of a low-cost adsorbent using aluminium-modified
activated carbon prepared from Khat (Catha edulis) stem as well as its adsorption effectiveness
for fluoride ion removal from aqueous solution. The fluoride adsorption capacity of the resulting
modified adsorbent was experimentally evaluated with batch adsorption experiments in
numerous operating conditions, which include pH, adsorbent dose, and fluoride initial
concentration. The results showed that the modified activated carbon retained good fluoride
performance; with an adsorbent dose of 2.47 g/L, 87.9 % of 2.1 mg/L initial fluoride
concentration could be reduced from aqueous solution containing at pH 6.08 in 60 minutes. The
adsorbent was applied to real drinking water samples collected from Tube, Wadesha, Dollessa,
and Tejitu, and it was discovered that the concentrations of ground water collected from Tube
and Wadesha were reduced from 3.67 mg/L and 4.33 mg/L to 1.0 mg/L and 1.28 mg/L,
respectively, and are within WHO permissible drinking water limits. The scanning electron
microscopy (SEM) and Fourier transform-infrared spectroscopy (FTIR) were used to describe
modified activated carbon and investigate the possible adsorption mechanism. The results show
that aluminium-modified activated carbon derived from khat (Catha edulis) has a reasonable
defluoridating capacity and could be used as an appropriate and effective adsorbent for a longterm
solution to the fluoride problem in drinking water with lower fluoride concentrations.
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Keywords
Fluoride Removal, Fluorosis, Khat Catha Edulis Stem, Adsorption