空気燃焼法によるケロジェンイオウ濃度の測定

Abstract

Determination of total sulphur concentration of kerogen by combustion method in air is examined. The combustion of sample was carried out at 950℃ for 10 min under flowing air of 2500 ml/min. Most sulphurs in sample are oxidized to be SO_2 by combustion. The sulphur dioxide is further trapped by H_2O_2 solution (ca. 3.0%) and reacted with H_2O_2 to be H_2SO_4. The determination of [SO^(2-)_4] in H_2O_2 solution by ion chromatograph and pH meter are examined, respectively. The direct determination of [SO^(2-)_4］by ion chromatograph is one of the most useful and precise analytical methods. While, the determination of [SO^(2-)_4] by pH meter ls based on the possible liner relationship between [H^+] and [SO^(2-)_4] in H_2O_2 solution. Kerogen samples often contain significant amount of halogen anions such as Cl^- and F^- because HCl and HF are generally used for the kerogen extraction. Another halogen anion, Br^-, can be significantly present in kerogen sample when we adopt ZnBr_2 solution as heavy liquid to separate neoformed fluorides and silicate minerals from HF／HCl treated samples. Those halogen anions can induce significant H^+ and obstruct the determination of [SO^(2-)_4]. However, results of [SO^(2-)_4] determination by pH meter for sufficiently washed kerogens are consistent well with ones by ion chromatography. If we sufficiently remove those halogen anions from kerogen samples, the indirect measurement of [SO^(2-)_4] by pH meter can be a fast and useful method to determine kerogen sulphur concentration.