INFLUENCE OF MICROORGANISMS ON THE DISSOLUTION OF METALLIC PLATINUM EMITTED BY AUTOMOBILE CATALYTIC-CONVERTERS

Platinum emitted by automotive catalyst converters mainly exists in th e metallic form, which is not bioavailable. Several investigations sho wed that finely dispersed metallic platinum is dissolved in organic ma trices to a significantly high degree [1,2]. In an exclusion experimen t, observations were made as to whether the transformation of Pt(0) an d other platinum compounds is mainly of a chemical nature or is influe nced by micro-organisms. A previous experiment [2], concerning the int eraction of several platinum compounds with a clay-like humic soil was repeated under sterile conditions to rule out the influence of micro- organisms. During the time of interaction (360 d), no significant diff erences were observed between the sterile and non-sterile modes. Thus, the dissolution of metallic platinum into soluble species, observed p reviously within this time period [2], seems to be mainly of a chemica l nature.