Direct Quantitative Analysis of Arsenic in Coal Fly Ash

Sri Hartuti,Shinji Kambara,Kazuhiro Kumabe,Akihiro Takeyama,Hiroshi Moritomi

doi:10.1155/2012/438701

Sri Hartuti, Shinji Kambara + Show 3 more

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https://doi.org/10.1155/2012/438701

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Abstract

A rapid, simple method based on graphite furnace atomic absorption spectrometry is described for the direct determination of arsenic in coal fly ash. Solid samples were directly introduced into the atomizer without preliminary treatment. The direct analysis method was not always free of spectral matrix interference, but the stabilization of arsenic by adding palladium nitrate (chemical modifier) and the optimization of the parameters in the furnace program (temperature, rate of temperature increase, hold time, and argon gas flow) gave good results for the total arsenic determination. The optimal furnace program was determined by analyzing different concentrations of a reference material (NIST1633b), which showed the best linearity for calibration. The optimized parameters for the furnace programs for the ashing and atomization steps were as follows: temperatures of 500–1200 and 2150°C, heating rates of 100 and 500°C s−1, hold times of 90 and 7 s, and medium then maximum and medium argon gas flows, respectively. The calibration plots were linear with a correlation coefficient of 0.9699. This method was validated using arsenic-containing raw coal samples in accordance with the requirements of the mass balance calculation; the distribution rate of As in the fly ashes ranged from 101 to 119%.

Highlights

Coal combustion byproducts predominantly consist of fly ash, bottom ash, and boiler slag [1]
Among the trace elements in coal fly ashes, arsenic, cadmium, copper, mercury, and lead are the greatest concern as environmental hazards [5]
Emphasis was placed on the optimization of the temperature of the furnace program and the use of chemical modifiers to minimize the potential interference

Summary

Introduction

Coal combustion byproducts predominantly consist of fly ash, bottom ash, and boiler slag [1]. If the arsenic concentration in the excess water exceeds the environmental limit (0.1 mg L−1 in Japan), the excess water cannot be drained into the sea This situation is serious, because ash storage must be discontinued. Graphite furnace atomic absorption spectrometry (GFAAS) is one of the most reliable and powerful analytical techniques for the determination of trace elements in water, soil, clinical, and biological samples [8, 9]. It offers good sensitivity with a short analysis time, low cost in comparison with inductively coupled plasma mass spectrometry (ICP-MS) [8], and requires a low sample volume (2–100 μL) [9]. Emphasis was placed on the optimization of the temperature of the furnace program and the use of chemical modifiers to minimize the potential interference

Experimental

Standards and Reagents

Results and Discussion

Conclusion