Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Arsenic Removal by Aggregated Nanoparticle Media
Yelda Meyva 1 *, Süer Kürklü 1 , Nilay Gizli 1 , 1
Department of Chemical , Turkey
1
Abstract- Arsenic, which is a toxic and accumulating substance in human body, has recently attracted great interest due to the high levels in
drinking water supplied from underground resources. Novel separation methods for the removal of arsenic use innovative products
developed by using nano materials. Among the commercial products, Adsorbsia GTO and MTM, are studied as adsorbents through batch
experiments in order to obtain the kinetics and mechanism of As(V) sorption. It is found that Adsorbsia GTO has larger sorption capacity
than MTM has, sorption equilibrium is best fitted by Freundlich Isotherm and transfer rate can be modelled by Liquid Film Diffusion.
Arsenic (As) is a widespread toxic contaminant in water
and is classified by the International Agency for Research
and Cancer (IARC) as a human carcinogen [1]. World
Health Organization (WHO), in 1993, recommended the
maximum total arsenic amount as 10 g/L. In 2002, the
USEPA lowered the maximu m contaminant level (M CL)
the new MCL became restrictive in January 2006, the
WHO, the European Union, and several countries recently
lowered the recommended or required arsenic limit to 10
[2-5]. In Turkey also in 2006, with a standard TSE
266 prepared by Ministry of Health, the maximum arsenic
concentration is lowered to 10 ppb level.
In this study, arsenic was selected as a target
contaminant because of its potential health and regulatory
concerns. Also, it has an ability to be adsorbed onto metal
oxide surfaces by forming inner-sphere bidentate ligands
[6]. Most heavy metals such as Pb 2+ , Cu 2+ and Ni 2+ occur
as cations in water while arsenic is an oxy-anion forming
element. This is particularly unique in its sensitivity to
mobilization at the pH values typically found in natural
waters. Although arsenic can exist in four different
oxidation states (
form in oxygen-rich environments. Under natural pH
conditions, species H 2 AsO 4 and HAsO 2 4 are the
dominant anions in water. As pH increases, the fraction of
divalent and trivalent arsenate anions also increases. Thus,
the treatment by adsorption is important because arsenic
cannot be reduced to harmless by-products unlike other
oxy-anions, such as ClO 4 or NO 3 , can [7].
In this study, two types of commercially available
aggregated nanosized materials, Adsorbsia GTO and
MTM ® containing different type of metal oxides, were
chosen for the removal of arsenic from aqueous solution.
While Adsorbsia GTO contains TiO 2 nanoparticles, MTM
consists of a light weight granular core with a coating of
manganese dioxide. First of all, the adsorption capacities
of these materials were obtained and compared with each
other. The capacity of Adsorbsia GTO is estimated as 19.9
mg As (V)/g-adsorbent while MTM has 0.35 mg As (V)/gadsorbent
capacity. Since TiO 2 based adsorbent exhibits
the higher As (V) sorption capacity , Adsorbsia GTO was
chosen as adsorbent for the studies followed.
For this purpose, both equilibriu m and kinetical
properties of GTO for the sorption of As(V) have been
investigated. Equilibrium behaviour of GTO has been best
characterized with Freundlich adsorption isotherm. Five
different kinetic models have been applied to fit the data
obtained by a series of batch experiments to find out the
mass transfer mechanism of the processes. The results of
statistical analysis indicate that the rate is determined by
the film d iffusion.
After this point, fixed bed column studies will be
conducted in order to obtain data to be modelled for design
purpose.
This study is supported by Ege University Research
Foundation by contract no: 09MÜH052.
*Corresponding author: 0Tyeldameyva@gmail.com
[1] US Department of Health and Human Services (Ed.),
Toxicological profile for arsenic, US Department of Health and
Human Services, Washington DC, 2000.
[2]World Health Organisation (WHO), Guidelines for Drinking
Water Quality, 1993, p. 41
[3]EPA, Technologies and Costs for Removal of Arsenic from
Drinking Water, EPA- 600-S-05-006, Office of Water (4606),
Environmental Protection Agency, Washington DC., 2000
[4]EPA, National Primary Drinking Water Regulations; Arsenic
and Clarifications to Compliance and New Source Contaminants
Monitoring, Final Rule, Federal Register, 66(15), 6975, 2001.
[5]EPA, Arsenic Treatment Technology Evaluation Handbook
for Small Systems, EPA-816-R-03-014, Office of Water (4606),
Environmental Protection Agency, Washington DC., 2003.
[6] Hristovski, K., Baumgardner, A., Westerhoff P., 2007.
Selecting metal oxide nanomaterials for arsenic removal in fixed
bed columns: From nanopowders to aggregated nanoparticle
media. Journal of Hazardous Materials 147 (2007) 265–274.
[7] Mohan D., Pittman C. U., “Arsenic removal from
water/wastewater using adsorbents”—A critical review, 2007.
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