Introduction:
Water contamination is a global problem that can
result in illness and death. Consumption of
contaminated drinking water is particularly
problematic in third world countries where
inadequate purification processes, coupled with
rapidly increasing population growth and
industrialization pose serious health risks. One of
the most common and deadly contaminants found in
water is arsenic (As). Arsenic, a heavy metal, is a
key toxic contaminant in the drinking water supply
of third world countries, often exceeding 10 μg/L
maximum limit set by World Health Organization
(WHO) regulations (World Health Organization,
2006). As contamination of drinking water is also
found domestically, where 13 million people in the
United States are affected by exposure; these
numbers dramatically increase where drinking
water restrictions are less rigid. For example, 45-57
million people in Bangladesh have been exposed to
10 μg/L or more of arsenic in water (Yang, 2010).
The necessity of an effective system to remove
arsenic from water is all too great. Current methods
employed in some countries lack sensitivity, and are
only effective in dealing with large concentrations
of arsenic in water, such as 100 μg/L. These
systems often leave residual As concentrations
above the 10 μg/L restriction set by WHO,
(Pittman, 2007). System enhancements are possible,
but the cost of improvements remains prohibitive
for many areas. However, recent studies have
demonstrated that iron oxides have a high affinity
for heavy metals such as arsenic and have opened
the door as a cost-effective way to remove
pollutants from water (Yavuz et al. 2009).
Ferrofluids, which are suspensions of nanoparticles
of magnetite (a ferrous-ferric oxide), are magnetic,
stable, colloidal, and homogenous. (Maity, 2006).
Such particles are typically suspended in a carrier
and can respond to a magnetic field but retain no
residual magnetism once the field is lifted.
Magnetite nanoparticles in a liquid carrier can be
manipulated by a magnetic field, retain no residual
magnetic properties, and have demonstrated the
general iron oxide affinity for heavy metals (Yavuz
et al 2009).
In the current investigation, the adsorption of
arsenic by magnetite nanoparticles was evaluated.
Additionally, methods and conditions that facilitate
the removal of As by nanoparticles was evaluated.
Results of optimized conditions were compared to
WHO standards and data from previous studies to
accurately gauge the accuracy of results and
applications thereon. Due to the small particle size,
easy manipulation, and cost effectiveness of
production, use of magnetite nanoparticles to
remove arsenic from water could prove to be very
feasible, particularly in less industrialized countries.
Altered conditions in this investigation were pH and
the surfactant type. Three types of nanoparticles
were tested- bare (uncoated), oleic acid coated, and
humic acid coated. Different methods regarding
nanoparticle generation and coating were attempted
before the final particles were generated, and were
then coated with oleic acid (Yavuz et al. 2009) and
humic acid (Liu et al. 2008) respectively.
Kushal Kadakia
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