BARC/PUB/2015/0676

 
 

An integrated approach based on oxidative pyrolysis and microwave-assisted digestion for the multi-elemental analysis of coal samples by ICP-based techniques

 
     
 
Author(s)

Krishna, M. V. B.; Chandrasekaran, K.; Chakravarthy, S.; Karunasagar, D.
(CCCM)

Source

Fuel, 2015. Vol. 158: pp. 770-778

ABSTRACT

Complete dissolution of the coal sample has been achieved using an integrated approach based on oxidetive pyrolysis (OP) and microwave-assisted digestion (MWD) for the quantitative determination of major to ultra-trace elements by inductively coupled plasma (ICP)-based techniques. The coal samples were initially pyrolysed by heating to ~500°C in the presence of an oxygen stream. Subsequently MWD was applied to the pyrolysed coal residue with an acid mixture of 8 mL of 20%HNO3+ 5%HF + 5%H2O2 or 20%HNO3+ 0.4%NH4HF2+ 5%H2O2. Analysis was carried out by ICP-MS (Be, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Cs, Ba, W, Tl, Pb, Th, U and REEs) and ICP-OES (Na, K, Ca, Mg, Fe, Al, Sc, Ti). Critical experimental parameters related to OP and MWD were optimized through the analysis of two standard reference materials (SRMs) NIST-1632d and NIST-2685b. Studies with NH4HF2 have demonstrated that it can be used as a replacement to the highly toxic HF for achieving quantitative recovery (>95%) of most of the elements studied here. The optimized method was subsequently applied to Indian coal samples collected from different coal mines.

 
 
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