ORIGINAL PAPER Properties of Biochars Obtained from RDF by Carbonization: Influences of Devolatilization Severity H. Haykiri-Acma 1 • G. Kurt 1 • S. Yaman 1 Received: 25 April 2016 / Accepted: 6 June 2016 Ó Springer Science+Business Media Dordrecht 2016 Abstract This paper criticizes the effectiveness of car- bonization as a thermal method to upgrade the fuel prop- erties of refuse derived fuel (RDF). For this purpose, RDF was subjected to carbonization at temperatures between 400 and 900 °C to monitor the changes in organic and inorganic portions of RDF, and its burning characteristics. The obtained biochars were characterized by proximate and ultimate analyses, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and ther- mal analysis (TG, DSC) methods. It can be concluded that carbonization is able to improve the calorific value of RDF only when this process is applied at 400 °C since serious losses took place in organic part at higher temperatures and increase in the ash yield overtook the improvement in the fixed carbon content. Besides, carbonization led to impor- tant reductions in the burning reactivity and the obtained biochars showed more reasonable burning characteristics in comparison to untreated RDF. Keywords Carbonization Á RDF Á Devolatilization Á Biochar Á Burning reactivity Introduction Municipal solid waste (MSW) is a kind of sustainable energy resource with high potential to achieve waste-to- energy approach. Besides, refuse derived fuel (RDF) is an alternative solid fuel that contains the combustible part of domestic/industrial wastes remaining after separation of the recyclable materials from MSW. The recyclables usu- ally account for 20–40 wt% of MSW [1]. Actually, RDF is a cheaper fuel than conventional fossil fuels and the gross calorific value of dried RDF varies in the range of 17–25 MJ/kg, arising from non-recyclable organic mate- rials including paper, packing wastes, woodchips, fabric, paperboard, plastics, food remnants etc. [2]. Mass burning and RDF burning are two options for MSW firing. In mass burning, the quality of fuel is usually low due to lack of sorting at the production site. Therefore, the life-cycle analysis favors RDF burning over mass burning because of the environmental impact and burning efficiency [3]. Social habits and activities play a significant role on the calorific value and the composition of RDF. Istanbul is the most populated metropolis in Turkey where fifteen million people live and nearly 6 million tons a year MSW is obtained. Kara [4] reported that RDF produced in Istanbul consists of textiles (66 %), paper (17.1 %), plastic bag (13.3 %), and PET and plastics (3.6 %). The use of this renewable and sustainable energy source also helps to avoid large landfill area that will be otherwise needed and greenhouse gas (GHG) emissions from the landfills can also be mitigated. It is of great interest to use RDF as an auxiliary fuel in co-combustion applications as long as the waste incinera- tion directives are followed. Power stations and cement plants have been incinerating this alternative fuel by blending coal [4–6]. However, in boiler applications where RDF is co-fired with coal, the ratio of RDF requires to be limited to avoid fluctuation in steam production, better control of steam temperature, and reduce corrosion prob- lem. Therefore, it is common practice not to increase the ratio of RDF above 20 % of total heat input on suspension & S. Yaman yamans@itu.edu.tr 1 Chemical Engineering Department, Chemical and Metallurgical Engineering Faculty, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey 123 Waste Biomass Valor DOI 10.1007/s12649-016-9610-5