Since the cellulose used in the production of tetrapak is of very high quality, the char generated during pyrolysis should be influenced mainly by the pyrolysis temperature. This article aims to determine the chemical composition of biochar prepared at the temperatures of 400, 500, 600 and 700 °C and its environmental properties determined by the presence of organic compounds with toxicity and relatively high mobility in the environment. The analytical pyrolysis of char was used to identify the following groups of organic compounds: alkanes, cycloalkanes, alkenes, cycloalkenes, alkynes, alkadiens, ethers, alcohols, nitrogen compounds, nitrils, ketones and aldehydes, compounds containing phenols, furans, benzofurans, PAHs (polycyclic aromatic hydrocarbons), carboxylic acids, compounds containing benzenes and markers indicative of the presence of synthetic polymers (polyethylene layers, a part of dyes, antioxidants, stabilizers), and fragments of cellulose. Concerning the use of char as a soil conditioner, its ecotoxicity was monitored (Folsomia candida) by monitoring its addition to the artificial soil (char addition: 0.5, 1, 2.5, 5, 10, 15, 20, 50 and 100%). The lowest reproduction inhibition of Folsomia candida is caused by biochar prepared at the temperature of 400 °C and 700 °C, but it is not suitable for the agricultural application, the concentration of PAHs is three times higher than the EBC limit. Low-density polyethylene which is present in the aseptic box in concentration of 6%, can degrade biochar so that it cannot be used as a soil amendment. The results of the char analyses show that the pyrolysis temperature is a decisive factor in the applicability of biochar.

Centre ENET Energy Units for Utilization of Non Traditional Energy Sources VŠB Technical University of Ostrava 17 listopadu 15 2172 708 33 Ostrava Poruba Czech Republic

CSIRO The Commonwealth Scientific and Industrial Research Organisation Energy 1 Technology Court 4069 Pullenvale QLD Australia

Department of Power Engineering Faculty of Mechanical Engineering VŠB Technical University of Ostrava 17 listopadu 15 2172 708 33 Ostrava Poruba Czech Republic

Institute of Environmental Engineering Faculty of Mining and Geology VŠB Technical University of Ostrava 17 listopadu 15 2172 708 33 Ostrava Poruba Czech Republic

Institute of Geological Engineering Faculty of Mining and Geology VŠB Technical University of Ostrava 17 listopadu 15 2172 708 33 Ostrava Poruba Czech Republic

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