Phosphate removal using aluminum–doped rice husk ash–derived silica
Date
2009-06-20Author
Salsuwanda, Selamat
Masitah, Hasan
Azlinda, Abd Ghani
Che Zulzikrami, Azner Abidin
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Show full item recordAbstract
Phosphate, a compound which has
phosphorus as its key atom, from excess fertilizers
and detergents ends up washing into lakes, creeks
and rivers. This overabundance of phosphorus
causes excessive aquatic plant and algae growth
and depletes the dissolved oxygen supply in the
water. In this study, aluminum–doped mesoporous
adsorbents were tested for their ability to remove
phosphate from water. Aluminum–doped rice
husk ash–derived silica (Al–RHA) was
synthesized by cogellation method and applied as
adsorbent for removal of phosphate in laboratory
batch adsorption studies. The synthesized Al–
RHA was characterized by nitrogen adsorption–
desorption, Fourier transform infrared (FTIR)
spectroscopy and scanning electron microscopy
(SEM). Al–RHA exhibited fast adsorption
kinetics as well as high adsorption capacities. The
optimum phosphate removal was determined in
initial concentration of 0.3 mg PO43–/L with 0.3 g
of adsorbent dosage at acidic condition after 3 h.
Freundlich isotherm was concluded to be the
preferred model for the adsorption process. The
regenerated Al–RHA was found to have 76%
phosphate removal capacity after being recycled
once. The amount of adsorbent and initial
concentration of phosphate solution had little
effect on the concentration of residual aluminum
ions, whereas the concentration of residual
aluminum ions decreases with the increase in pH
of the solution.