The Malaysian Journal of Analytical Sciences Vol 12 No 2 (2008): 375 – 379
ANALYSIS OF
TRACE ELEMENTS IN POWER PLANT AND INDUSTRIAL INCINERATOR FLY ASHES BY
INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS (INAA)
Wadeeah M. Al-Areqi*, Amran Ab. Majid, and Sukiman Sarmani
Programme of Nuclear Science,
Faculty
of Science and Technology, Universiti Kebangsaan
43600
Bangi, Selangor
*Corresponding
author: walareqi@yahoo.com
Abstract
An elemental
analysis of fly ash samples
from Selangor & Perak coal-fired
power plants and an industrial incinerator from Negeri Sembilan were carried
out using instrumental neutron activation analysis (INAA). All samples were
irradiated at the Malaysian Nuclear Agency laboratory PUSPATI Reactor for 6
hours and later counted at the Nuclear Science Program, UKM using an HPGe
detector with a relative efficiency of 10% and resolution of 1.8 KeV (FWHM) at
1.33 MeV. International Atomic Energy Agency (IAEA) coal fly ash 1633a
reference material (SRM) was used as a standard for quantitative analysis. A
total of 11 elements (i.e. As, Ba, Ca, Ce, Cr, Co, Fe, Hf, Sc, Th and U) were
determined in all three types of fly ashes. The concentration range of environmentally
concern elements, As and Cr in the Selangor coal-fired power plant samples are
11.17 - 23.24 and 160.28 - 867.97 μg.g-1 respectively. The
concentration range of radioactive elements U and Th are 4.79 - 10.29 and 14.6 -
61.29 μg.g-1 respectively, and the concentration
range of Co, Hf, Fe, Sc, Ba, Ce, Ca are 11.88-83.61, 3.24 - 10.48, 30338 - 53885,
16.62 - 28.48, 178.97 - 8491, 127.41 - 217.2 and 10447 -20647 μg.g-1
respectively. The concentration range of As, Cr, U, Th in the Perak samples were found
to be 22.16 - 48.38, 44.37 - 74.78, 4.18 - 6.85, 8.71 - 11.43 μg.g-1
respectively, whereas the concentration
range of Co, Fe, Sc, Ba, Ce and Ca are 23.21 -29.66, 54621 - 71099, 30.9 - 31.77,
100.34 - 116.61 and 11533 - 16423 μg.g-1 respectively. Differences exist in the elemental
concentrations of both power plant fly ash samples due to the different feed
coal and combustion temperature used. The concentration of Cr, Th and Ce in the
Selangor fly ash samples was generally higher compared to the samples obtained from
the Perak power
plant. This study also shows that only As and Ca were detected in the Negeri
Sembilan samples with the concentration ranging from 36.66 - 98.67 and 31709.10
– 45606 μg.g-1 for As and Ca respectively. The results indicated
that the concentration of As and Ca in the industrial incinerator fly ashes are
higher compared to the concentration of the same elements in the two power
plants. The variations of elemental existence and concentration in the industrial
incinerator and power plant fly ashes samples depend on the differences in
compositions and characteristics of the feed sources and combustion
temperature.
Keywords: trace elements, power plant and
industrial incinerator fly ashes, INAA
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