HIGHLIGHTS:
Mesoporous structures predominate in all samples.
Surface area and pore volume increase due to the heat treatment.
Poultry litter subjected to 250, 350 and 450 °C shows similar physical, chemical and structural characteristics.
ABSTRACT
This study aimed to investigate the effect of heat treatments on the total pore volume, surface area of pores, structural characteristics, and functional groups of the materials which derive from the carbonization and pyrolysis of poultry litter. These processes were carried out in porcelain containers containing poultry litter samples, which were then placed in a muffle furnace. The treatments corresponded to three temperatures: samples carbonized at 250 °C and pyrolyzed at 350 and 450 °C. The surface porosity of biochars provides a suitable dimension to improve the water holding capacity, and surface functional groups may help to improve soil fertility. The influence of the temperatures on the pores of the biochar was investigated by using scanning electron microscopy with energy-dispersive x-ray spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The characterization of the biochar shows mesoporous structures, as well as increased surface area and pore volume. The chemical composition has potassium at higher concentrations than other metals, while similar surface functional groups were found in the biochar, such as phenolic, aliphatic, conjugated quinones, and OH-phenolic. The thermal treatments applied to poultry litter generated samples with similar physical, chemical, and structural characteristics. Thus, the production of biochar by the farmer and its use as a soil conditioner can contribute to the reduction of agricultural pollution, management, and efficient disposal of residual biomass.
Key words:
BET surface area; pore volume and surface; chemical composition; functional groups
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