To measure cation exchange capacity (CEC) of materials like shales a methylene blue method based on the API protocol is used. For this analysis we require a minimum of 1 gram of sample (dried weight) which is sieved to <75 microns. The sample is placed in a conical flask and then boiled in a solution of hydrogen peroxide and sulphuric acid (pictured below left), before methylene blue is titrated into the flask in 1 ml aliquots (pictured below right). The CEC is taken when a corona forms around the droplet placed on the filter paper (pictured below centre).

Other CEC methods are available, please contact us for details.