Experimental modeling of platinum sorption on organic matter

In connection with the discovery of a new type of Pt deposit in low-rank brown coals and black shales, the interaction of Pt-bearing aqueous solutions with fractionated organic matter (asphaltenes and asphaltenic acids) was studied at 200–400°C and 1 kbar total pressure. It was found that chemical sorption onto the organic matter lowers Pt content in the aqueous solutions by about two orders of magnitude relative to organic-free systems. Thermal maturation of the asphaltenes leads to its aromatization and concomitant sorption of Pt from n×10−4 mPt (mol per kg of dry matter) at 200°C to n×10−2 mPt at 400°C. Thus, the Pt chemisorption on activated carbonized organic matter may be an effective mechanism of Pt accumulation in C-bearing rocks.