Abstract
Activated carbons are widely used for the purification of water and air. This includes the treatment of gaseous and liquid industrial waste streams prior to release as well as the provision of pure drinking water and the remediation of environmental contamination. Activated carbons are any amorphous carbon which has a large surface area for adsorption and are thus suited to the above purposes. The preparation of activated carbons requires costly and energy intensive treatments to increase their porosity. Biochar is a proposed approach to the amelioration of anthropogenic climate change by burying carbon as charcoal, a process which has been demonstrated to improve the productivity of soil. In this work a range of biomass precursors (various plants and agricultural by-products) are studied for their potential to produce high surface area carbons when subject to pyrolysis treatment. The variations in precursor chemical composition which affect the porosity of the final carbon are identified and mechanisms of this intrinsic activation process are suggested from experimental data. The goal of these investigations is the development of a single step pyrolysis process allowing the simultaneous production of activated carbon, bioenergy and chloride or nitrate salts. Such a process is shown to have substantial economic advantages over a pyrolysis process which produces energy alone using comparable equipment. The improved economics of such a process could allow the realisation of the biochar concept by creating economies of scale around the production of porous carbons. It is argued this would allow the use of porous carbons on a large scale for cleaning up pollution and improving the productivity of the world’s arable land. An additional positive outcome would be helping to ameliorate anthropogenic climate change by direct carbon burial.