ORIGINAL ARTICLE Properties of sago waste charcoal using hydrothermal and pyrolysis carbonization Herman Siruru 1,2 & Wasrin Syafii 1 & I. Nyoman J. Wistara 1 & Gustan Pari 3 & Ismail Budiman 4 Received: 15 June 2020 /Revised: 21 August 2020 /Accepted: 26 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract The thermochemical biomass conversion has widely used because it is considered environmentally friendly and carried out at low temperatures and pressure to reduce costs. Hydrothermal and pyrolysis carbonization are two kinds of biomass conversion that widely practiced in the current time. In this study, hydrothermal and pyrolysis carbonization was carried out using sago wastes in bark and pith form. The purpose of this research was to compare the charcoal properties between chars from hydrothermal and pyrolysis carbonization. In this study, the carbonization process was conducted in two methods, i.e., hydrothermal and pyrolysis carbonization. The hydrothermal carbonization was performed with a temperature of 250 °C for 4 h, using rotary digester with water as a medium. While the pyrolysis carbonization was conducted with a temperature of 400 °C for 5 h, using a vacuum electrically heated tube as a reactor. The characterization of chars performed was proximate and elemental analysis; iodine number; calorific value; Fourier-transform infrared (FTIR); X-ray diffraction (XRD); scanning electron microscope (SEM); Brunauer, Emmett, and Teller (BET); and pyrolysis-gas chromatography-mass spectroscopy (Pyr-GC-MS). The results showed that the iodine adsorption capacity, surface area, and pore volume of chars from hydrothermal were higher than pyrolysis. In contrast, the calorific value of chars from pyrolysis was higher than the chars from hydrothermal. Based on results, chars from hydrothermal can be used as a precursor of activated charcoal specifically for adsorbent, while chars from pyrolysis are potential energy sources. Keywords Sago waste . Charcoal . Hydrothermal carbonization . Pyrolysis carbonization . Characteristics 1 Introduction One of the lignocellulosic biomass rich in carbohydrates has high potential in Indonesia, and several Southeast Asian coun- tries are sago (Metroxylon sp.). This plant has economic value because it can produce flour, used as a food ingredient [1]. Utilizing sago plants as food material produces waste, which is three times the amount of starch [2]. The existence of this sago plant waste which is large enough to provide opportuni- ties to utilize in other fields, such as renewable energy sources. Previous research has shown that sago plant waste contains compounds that can use as an energy source in the form of biofuels [3–5]. The use of energy sources from renewable natural re- sources; for example, sago plants, becomes an exciting con- cern to study. The use of sago plants is due to depleting fossil energy reserves and environmental problems. The production process, as far as possible, is expected to use less energy. Charcoal is a thermal conversion product that is generally carried out by the pyrolysis method. The thermal decomposi- tion process produces charcoal, which has different properties according to the time, heating speed, and pyrolysis tempera- ture. Pyrolysis with a long time, slow heating, and a temper- ature higher than 400 °C is called carbonization [6]. The car- bonization process breaks down organic matter into carbon (charcoal), occurring at temperatures between 400 and 600 °C, and heating slowly at around 400 °C for release tiny of carbon. Activated charcoal is more effective using * Herman Siruru sirherman78@gmail.com 1 Department of Forest Products, Faculty of Forestry, IPB University, Kampus IPB Darmaga, Bogor 16680, Indonesia 2 Departement of Forestry, Faculty of Agricultural, UNPATTI, Ambon 97233, Indonesia 3 Forest Research and Development Agency, Gunung Batu, Bogor 16118, Indonesia 4 Research Center for Biomaterials LIPI, Jl Raya Bogor km 46 Cibinong, Bogor, Indonesia Biomass Conversion and Biorefinery https://doi.org/10.1007/s13399-020-00983-9