The behavior and removal of silicon dioxide nanoparticles in synthetic aqueous systems
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Date
2019-06
Authors
Noradila Binti Abdul Raof
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Abstract
A study was conducted using both chemical (polyaluminium chloride (PACl) and
polymer) and natural (pectin) coagulants for the removal of silicon dioxide nanoparticles
in synthetic aqueous systems to stimulate the pollution concentrations found in
semiconductor wastewater. The average of zeta potential and particle size as a function
of pH 2 to 12 were carried out separately for the synthetic silicon dioxide and selected
coagulants in determining the optimum pH. The optimum pH for silicon dioxide was at
pH 4 with a zeta potential of -21 mV and average particle size of 258.2 d.nm.
Furthermore, the optimum pH for polyaluminium chloride was at pH 7 with a zeta
potential of +62.0 mV and average particle size of 182.4 d.nm. The optimum pH values
for both polymer and pectin were at pH 5 with a zeta potential of -30.7 mV and -52.9
mV and average particle size at 760.5 d.nm and 1152 d.nm respectively. The interaction
between the silicon dioxide and selected coagulants were carried out in order to
determine the optimum coagulant dosage range by applying mixing speeds of 300 rpm
(rapid) and 25 rpm (slow) with a settling time of 30 minutes. From the results, the
optimum dosage of polyaluminium chloride, polymer, and pectin were at 15 mg/L, 11
mg/L and 3 mg/L respectively. The coagulation process between the interaction of silicon
dioxide NPs and selected coagulants were further validated using the jar test method. The
results of the jar tests showed that polyaluminium chloride, polymer, and pectin can
remove 97.8%, 97.8%, 97.6% of silicon dioxide concentration in the aqueous system.
The removal percentage of pectin recorded similar performance to the commercial
coagulants. Therefore, it can be concluded that natural biopolymer coagulant such as
pectin has properties to perform equally good as polyaluminium chloride and polymer in
the removal of silicon dioxide nanoparticles in aqueous systems.