Method for quantifying the pyrogenic carbon present in a sample of an organo-mineral or mineral matrix comprising charcoal and/or biochar

A process for quantifying pyrogenic carbon content present in a sample of an organo-mineral or a mineral matrix and at least one of charcoal and biochar, comprising:

• A) heating the sample under an inert atmosphere according to a first temperature sequence, with an initial temperature of between 100 and 300° C., and a final temperature of between 50° and 800° C.;
• B) heating a residue of the sample resulting from the heating under an inert atmosphere, under an oxidizing atmosphere according to a second temperature sequence with an initial temperature of between 10° and 300° C., and a final temperature of between 70° and 1000° C., and measuring at least one amount of CO2 released during the second temperature sequence;
• C) based on a curve representing a temperature-dependent evolution of the quantity of CO2 released during the heating in an oxidizing atmosphere, breaking the curve down into at least a first and a second component, the first component corresponding to a part of the curve associated with temperatures below a temperature limit, and the second component corresponding to a part of the curve associated with temperatures equal to the temperature limit or greater than the temperature limit wherein the temperature limit is between 500° C. and 550° C.;
• and
• D) determining the pyrogenic carbon X3 present in the sample resulting from the surface areas of the first and second components, according to a formula:
• X
• 3
• =
• X
• 2
• -
• A
• ·
• X
• 1
• 1
• +
• A
• ·
• B
• in which X1 and X2 are carbon contents determined respectively from surface areas of the first and second components, A is a coefficient representing a proportion of the matrix in the second component relative to the first component, and B is a coefficient representing a proportion of the at least one of the charcoal and the biochar in the first component relative to the second component.