CALORIFIC VALUE AND INORGANIC MATERIAL OF TEN MEXICAN WOOD SPECIES

The calorific value and ash content of bark, sapwood and heartwood of ten tree species (Agarista mexicana, Arbutus glandulosa, A. xalapensis, Clethra macrophylla, Eucalyptus citriodora, E. robusta, E. saligna, Persea americana, Prosopis laevigata, Schinus molle) were determined. The ash was analyzed by means of x-ray. The calorific value ranged from 15.01 to 18.87 MJ.kg(-1) for bark, from 15.01 to 18.89 MJ.kg(-1) for sapwood and from 17.40 to 419.11 MJ.kg(-1) for heartwood. The bark contained between 0.83 and 3.6 % ash, the sapwood contained 0.25 to 3.54 % ash, and the heartwood contained between 0.22 and 2.1 % ash. In general, the calorific value followed the trend: heartwood > sapwood > bark, while the mean ash percentage followed the reverse order. There was a negative correlation between ash content and calorific value. Common chemical elements present in all ash samples included calcium, potassium, magnesium and phosphorus. Heavy metals were not detected in bark or wood samples.