Abstract
The adsorption of zinc n-, iso-, and s-dibutyldithiophosphates from n-hexadecane on iron and iron oxide powders was investigated in static conditions. The effects of ZDTP concentration, time, and temperature were examined. ZDTP adsorption isotherms on both powders are very similar and are S-type. The adsorption kinetics cannot be represented by a Langmuir model. At higher temperatures, oxidation of ZDTP occurs on iron oxide surface; chemisorption sulfur products which are formed on iron surface were determined.