Production and characterization of synthetic wood chars for use as surrogates for natural sorbents

Abstract

Wood char is an important source of environmental black carbon that affects the fate of organic contaminants in soils and sediments and plays a role in carbon cycling. Currently, the research community has need for char standards for laboratory use that are representative of naturally occurring chars. This investigation presents a scientific approach to the production of synthetic chars that have properties of a natural char produced by forest fire. The natural char examined for this purpose was that of a pitch pine obtained from the New Jersey Pine Barrens; however, the developed characterization approach is more generally applicable toward understanding and producing surrogate synthetic materials for any natural wood char. Small blocks of pitch pine wood were pyrolyzed using ramp rates between 30 and 1000 °C/h and with maximum temperatures between 450 and 1000 °C. The chars were then characterized using helium-based solid density, electrical resistivity, H/C ratio, PAH analysis and surface area measurements. A comparison of these key parameters among the synthetic and natural chars clearly demonstrated that the natural char had experienced maximum temperatures of 500–600 °C. Additional studies based on re-heating suggest that the char had experienced very rapid heating rates (greater than 200 °C/h) during its formation.