RESUMO
Different methods of purification and drying of sericin were evaluated to obtain a material free of contaminating residues through the development of safer and sustainable environmental technology. Samples purified using different proportions of alcohol solvents and by freezing/thawing were compared, while drying was performed by lyophilisation and atomisation in a spray. No significant statistical differences were observed in the yield of the purification process compared with the evaluated methods. Thus, the freezing/thawing method has economic and environmental advantages over other methods. Drying by spraying and lyophilisation produced particles exhibiting different properties in terms of structure: ß-sheets, random sheets, and ß-turns. In general, these particles are amorphous. The particles obtained by spray drying were more luminous, soluble, and spherical. Thus, purification by freezing/thawing and drying by spray can be considered appropriate methodologies for obtaining contaminant-free sericin through sustainable environmental technology.
RESUMO
For the photocatalytic degradation of the hydrogen sulphide (H2S) in the gas-phase it was developed a rectangular reactor, coated with acrylic paint supported on fiber cement material. The surface formed by the paint coverage was characterized structural and morphologically by scanning electron microscopy with energy dispersive X-ray and X-ray diffraction analysis. The flow rate and the inlet concentration of H2S were evaluated as operational performance parameters of the reactor. Removal efficiencies of up to 94% were obtained at a flow rate of 2â Lâ min-1 (residence time of 115â s) and inlet concentration of 31â ppm of H2S. In addition, the H2S degradation kinetics was modelled according to the Langmuir-Hinshelwood (L-H) model for the inlet concentrations of 8-23â ppm of H2S. The results suggest that flow rate has a more important influence on photocatalytic degradation than the inlet concentration. It is assumed that H2S has been oxidized to SO42- , a condition that led to a deactivation of the photocatalyst after 193â min of semi-continuous use.