Abstract:Pyrolysis is an effective method to treat waste bones from livestock slaughter and a large amount of chars, which can be effectively used as adsorbents and other materials, are produced in the pyrolysis process. Based on the thermogravimetry, Fourier transform infrared spectroscopy and mass spectrometry (TG-FTIR-MS) as well as scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), the pyrolysis process and product information of bovine bones and porcine bones were systematically studied. The release characteristics of gaseous products had a relationship with the characteristics of thermogravimetry. More organic gases were produced in porcine bones during pyrolysis because of the high fat contents, including CH4，C2H4，and C2H6. CO2 and NH3 were released in the main pyrolysis stage (350~600℃). The aromaticity of bone char formed and was at a relatively high level at 500℃ and bone chars had a strong stability. During the carbonization stage, a small amount of CO was gradually released, and substances containing metal carbonyls were formed in the char. C was lost in the form of gas, while Ca and P accumulated during pyrolysis and remaind in inorganic components such as hydroxyapatite (Ca10(PO4)6(OH)2). Further, bovine bone char and porcine bone char were prepared at different pyrolysis temperatures (500~900℃), and the yields of them were maintained at 60% and 50%, respectively. The yield of low-temperature chars was higher. For the two types of bone char, the pyrolysis temperature and the types of raw materials had certain effects on their physical and chemical properties. The alkalinity and ash content of the bone char were increased with the increase of the pyrolysis temperature. The ash content of bone chars exceeded 90% at 900℃, and the pH value of the bovine bone char was significantly higher than that of porcine bone char. As the pyrolysis temperaturewas increased, the pore volume of bone char was decreased and the pore diameter was increased. The BET specific surface area of bovine bone char prepared at 500℃ was 172m2/g, and its pore structure was more conducive to physical adsorption. The research results can provide theoretical basis and data support for the pyrolysis treatment of livestock bone and the production and application of bone char.
