Determination of Minor Elements in Walnut Shells (Juglans regia L.)

The content of individual macro- and micro-elements in solid biofuels has a significant impact on the processes involved in their combustion. An excessively high content of certain elements can lead to the formation of sludge or corrosion of furnaces. It is therefore important that a raw mate-rial used for energy purposes should meet the requirements contained in specialised standards for the energy industry. The main purpose of this study was to obtain information on the content of some minor elements in walnut shells, a potentially widely used raw material for energy purposes. It investigated the content of minor elements (Cr, Cd, As, Cu, Ni, Zn, Pb, Hg) in walnut (Juglans regia L.) shells from three locations in Poland. The trees where the nuts were harvested were not subjected to any chemical treatment that could affect the results of the study. In addition, the paper includes information on global walnut production. The study shows that it is possible to use walnut shells as a material for solid biofuels. The values obtained are generally lower than those for broadleaf and coniferous wood.