Modified Walkley-BIack method for the determination of Total Organic Carbon (TOC) in ferrous iron rich rock samples and its correlation with Loss-on-Ignition (LOI)

摘要

A modified Walkley-Bfack (WB) volumetric method for the determination of Total Organic Carbon (TOC) in ferrous rich rock samples has been developed. High amount of ferrous being an interferent in the determination of TOC needs to be removed. The removal of ferrous was carried out using hydrofluoric acid treatment followed by TOC determination by Walkley-BIack method. In the present study, the temperature profiling using Muffle furnace was carried out to ascertain the loss of organic matter by combustion and correlate the TOC values as obtained by modified Walkley-BIack method. This combustion technique and the modified method was applied on black shale samples obtained from Loharka, Dehardun area and few synthetic samples rich in ferrous ions. Study regarding temperature profile of high ferrous and black shale samples done by a temperature controlled Muffle furnace, suggests that, the fraction of weight loss between 450 to 500 °C corresponds to the TOC values. The values obtained by both the methods were in good agreement with the values obtained from TOC analyser.