Pore structure and surface chemistry of adsorbents obtained by pyrolysis of sewage sludge-derived fertilizer Original Research Article

Terrene®, a fertilizer product derived from New York City municipal sewage sludge, was pyrolyzed at various temperatures between 400 and 950°C. The pore structure and surface chemistry of the adsorbent materials obtained were characterized using nitrogen adsorption, thermal analysis, potentiometric titration and FTIR. The adsorbents contain a high percentage of inorganic matter (up to 70%) and only up to 30% carbon. The results show that microporosity is developed within the carbon deposit and at the organic/inorganic interface with increasing temperature of heat treatment. An increase in the pyrolysis temperature also results in significant changes in the surface chemistry towards the development of basic nitrogen centers. In particular there was an increase in the pH values of adsorbents’ surfaces from 7 to 11.