Adsorption of copper by peat, lignite, and bituminous coal

Abstract

The degree of adsorption of Cu by a peat, a lignite, and a bituminous coal was determined and a mechanism for the adsorption process was proposed. In the course of the investigation the mode of occurrence of Cu in the coals was established. Samples utilized were selected to be representative of the range of organic material known to occur in the colorimetric spectroscopy, and wet chemical techniques. Copper was organically associated in the coals and was complexed with humic acids. The complex involved was probably the carboxylic group. Adsorption of Cu decreased with increased coalification, with peat exhibiting the greatest adsorptive capacity because of its high humic acid content. Increased compaction of organic materials, accompanied by a decrease in surface area during coalification, resulted in decreased Cu adsorption, and by the formation of the coal phase, adsorption of Cu had essentially ceased.