Oxygen and nitrogen in coal by instrumental neutron activation analysis

Abstract

The feasibility of using fast neutron (14 MeV) activation analysis techniques for the determination of oxygen and nitrogen in coal has been investigated. Conditions that favor instrumental neutron activation analysis (INAA) include the absence of problems associated with sample dissolution and the capability of extremely rapid analyses as compared to older techniques such as the Kjeldahl method for nitrogen. Most previous oxygen determinations have been by difference after major component analyses. In the present study, oxygen was determined in sized coal and its low temperature ash (LTA) with the difference representing the organic oxygen content. Both the oxygen and nitrogen analyses employ a multiscaling technique with the former based on the16O(n, p)16N reaction, while the latter utilizes the annihilation radiation produced by the product of the14N(n, 2n)13N reaction. The high-energy gamma-radiation associated with the decay of16N was essentially free of spectral interferences for coal analysis, although fluorine could cause a primary interference if the F/O ratio exceeds 0.02. In the nitrogen work, experiments were performed to determine correction factors to account for the effects of the12C(p, γ)13N and13C(p, n)13N “knock-on” reactions and the39K(n, 2n)38K reaction which produce interfering β+ emitting radionuclides. Data are presented for oxygen in Western Kentucky No. 9 and No. 11 coal and coal ash and for nitrogen in eleven different coals.