Fluoride ion is present in high concentration in some regions in Syria. As
fluoride occurs naturally in water, We have studied some methods of fluoride
removal such as Nalgonda technique and activated carbon method.
In Nalgonda technique we add Al
um and lime to the water, and we have
found that fluoride removal efficiency remains constant when the initial
concentrations of fluoride changes, or when the chloride ions exists in water,
but it depends on pH, and get better when the method is investigated in two
steps. In addition, adsorption of fluoride decreases with increasing
sedimentation time, or using Ventilated lime or CaCO3 instead of Ca (OH)2.
In activated carbon method we have done different experiments by using
charcoal of coconut coir, date seeds and olive seeds. And we have found that
olive seeds carbon is better than others, and its fluoride removal efficiency
increases after impregnation with solution of 2% Al2(SO4)3.
Four different brands of black tea and one brand of green tea commonly
available in Syrain markets were tested to measure the level of fluoride
contained in their liquid using four different methods of infusion and utilizing
the spectrophotometer
technology: A. Infusion without boiling. B. Infusion with
boiling. C. Repeated infusion. D. Continuous infusion.
The results have indicated that the average level of fluoride in the samples
of black tea liquid is higher than the one in the green tea sample regardless of
the infusion method used. Also, it was found that the level of fluoride released
from all samples is higher when boiling them in water from 1 to 5 minutes. In
addition, it was proved that the level of fluoride in tea liquids is higher when
it’s prepared using repeated infusion, but it’s lower when the tea has been
prepared using the continuous infusion method. Tea brands (2) and (4) released
the highest level of flouride 7.37mg/L and 5.01mg/L respectively, which are
very high levels comparing to the other brands which released between 1.5mg/L
to 2.7mg/L. To prevent fluoride from reaching poising levels, the total daily
consumption of black tea liquid of brands (2) and (4) should not exceed 1.76L
and 2.58L respectively and to avoid preparing them using the repeated and
countinous infusion methods.
