Abstract:
during their growth. A concentration greater than 1.5 mg/L in drinking water has several
detrimental effects on human health, including dental and skeletal fluorosis. There are
several methods employed to rid water of fluorides. These include, reverse osmosis,
adsorption, ion exchange, coagulation and flocculation. This study focuses on removal
of fluorides from aqueous solutions by coagulation using quaternary ammonium
functionalized waste paper bio-coagulant. Quaternary ammonium compounds were
synthesized from waste paper by first nitrating cellulose present in waste paper. The
attached nitro groups, were reduced to amine groups and quaternization was done
using methyl iodide. The prepared bio-coagulant was characterized using FTIR and
TGA. The coagulant was used to remove fluorides from model solutions and real water
samples from Gilgil area in Nakuru County, Kenya. A fluoride ion selective electrode
was used to determine fluoride ion concentration in each model solution and in the
real water samples. Optimized parameters included pH, initial fluoride ion
concentration, contact time and bio-coagulant dosage. Characterization data confirmed
successful quaternization was achieved. Thermal stability of the material was up to a
temperature of 563.15 K. The optimum pH value was 4.0 while the contact time was
15 minutes. Fluoride removal increased with increase in initial concentration up to an
optimum 20 mg/L. Fluoride removal was also observed to increase with increase in
coagulant dosage. Obtained data fitted well on Langmuir adsorption isotherm with R2
value of 0.9707, confirming chemisorption as the predominant intermediate process.
An adsorption capacity of 3.6311 mg/g was obtained. Fluoride ion removal percentage
in the model solution was 81% and 66.25% in the real water sample. It is evident from
this study that used waste paper can be modified and used to treat water containing
fluorides.
