Reaproveitamento de resíduos de ossos suínos provenientes da agroindústria para produção de bio-óleo e carvão ativado

Abstract

Brazil is considered the fourth largest producer of pork meat in the world and, as a result, large amounts of waste from slaughter are generated, mainly in the southern region of the country. Among these residues, pork bones stand out, produced on a large scale and with low added value. Therefore, the present work aimed to reuse the agro-industrial residue (pork bones) for the production of bone char, bio-oil and gases through the pyrolysis process. The residues were obtained from a food industry. These were subjected to pre-treatment (removal of meat remains and drying) and subsequent characterization by means of immediate (moisture, volatile material, ash and fixed carbon) and thermogravimetric analysis (TGA). The pyrolysis of the pork bones was carried out in a fixed bed, in an atmosphere of N2, using different temperatures (450 to 850 °C). Char (biochar), pyrolytic liquid and gases were obtained as products of the process. The pyrolytic liquid was separated into two phases (aqueous and organic) and analyzed for pH, higher calorific value (PCS), evaporation loss and density. The coal obtained in the pyrolysis at 850 °C was subjected to activation with CO2 at the same temperature. The char from the pyrolysis, the activated carbon with CO2 and a commercial bovine bone carbon (used as a reference) were characterized by means of Scanning Electron Microscopy (SEM), iodine number, pH at zero charge point (pHpcz), spectroscopy Fourier Transform Infrared (FTIR), X-Ray Diffractometry (XRD), PCS and TGA. Pyrolysis of pork bones yielded, on average, 53.6% biochar, 30.2% pyrolytic liquid and 16.2% gases. The properties of the aqueous and organic fractions were not influenced by the pyrolysis temperature. Both fractions showed alkaline pH (> 9.1). For organic fraction (bio-oil), the calorific value presented an average value of 38.31 kJ g-1, indicating a potential for its use as biofuel. For the pyrolysis coals, the results indicated a porous material whose main constituent is hydroxyapatite, from the composition of bones. The properties of pyrolyzed charcoals at higher temperatures (750 and 850 °C) were similar to those of commercial beef bone charcoal. The activation process with CO2 had a negative influence on the material properties, and its implementation is not indicated. In the adsorption tests, the pyrolyzed char at 850 °C showed higher performance in relation to the other samples (pyrolyzed, activated and commercial bovine bone char) in the removal of iodine and a textile dye. Thus, the reuse of pork bone waste through the pyrolysis process can bring important advantages and benefits such as the generation of value-added products (biochar and renewable liquid fuel - bio-oil), more jobs and solutions to environmental problems.