Pyrolysis of Pinus halepensis needles treated with fire retardants

Abstract

The effect of various chemical fire retardants: (NH4) 2SO4, (NH4)2HPO4, a commercial retardant contained 10% w/w phosphate salt, on the pyrolysis mass residue of Pinus halepensis needles was studied on preparative-scale. Samples of 2.00 g were treated under isothermal (400°C and 500°C) and non-isothermal conditions (50-500°C), with pyrolysis time between 0.00-3.00 h. The results of this study were found similar with those obtained with much lower sample sizes (i.e., 6 mg) used in analytical methods such as Thermogravimetry (TG). The phosphate based retardants had the most significant action, under the experimental conditions used. However, the retarding effect was reduced, when the phosphate retardants were diluted in sea water. This might be attributed to the formation of insoluble salts (i.e., MgNH 4PO4). Such reactions might bind the active phosphates, thus reducing the fire retarding effect.