Vitor Renan da Silva

High Molecular Sericin from Bombyx mori Cocoons: Extraction and Recovering by Ultrafiltration

The present study focus on sericin extraction process from Bombyx mori cocoons using water in absence of chemical additives under different physical conditions aiming to obtain high molecular weight sericin. Separation and fractionation of sericin proteins to obtain high molecular weight material was also carried out using ultrafiltration process at different operating modes: batch, diafiltration and batch with back flushing water pulse. The molecular weight of extracted sericin protein using pure water showed in general a size distribution varying from 20 up to 400 kDa, with major peaks between 200 kDa and 100 kDa and peaks with fraction of sericin lower than 100 kDa, depending on conditions used in the extraction and concentration. The results demonstrated viability to separate sericin fractions having molecular size higher than 50 kDa, using the ultrafiltration process with 50 kDa cut-off membrane, however, a flux decline above 90 % was detected independent of operating mode. Increasing the concentration factor from 2 to 4 promotes the permeation of sericin molecules of high molecular weight, reducing the rejection coefficient of 71.1 % to 60.4 %.

Equilibrium, kinetic, and thermodynamic studies on the biosorption of Bordeaux S dye by sericin powder derived from cocoons of the silkworm Bombyx mori

AbstractThe biosorption of Bordeaux S dye onto sericin powder derived from silkworm cocoons was studied in a batch adsorption system to determine the kinetic mechanism, the equilibrium, and thermodynamic parameters. The Langmuir, Freundlich, and Temkin isotherm models were used for the equilibrium modeling. In order to describe the kinetics, the fits of pseudo-first-order, pseudo-second-order, Weber–Morris, Crank, and external liquid film diffusion models were evaluated. The adsorption occurs favorably at pH below 3.2. The kinetic and equilibrium studies showed fast adsorption and interaction were limited to the monolayer surface, with pseudo-second-order and Langmuir models providing the best fits. Thermodynamic studies indicated that the system is spontaneous and exothermic and that physical interactions govern the adsorption process. The results revealed that sericin powder has the potential to be used as a biosorbent for the treatment of wastewater containing the dye Bordeaux S.

Pretreatment of Aqueous Pectin Solution by Cross-Flow Microfiltration: Study on Fouling Mechanism

This research was carried out to determine the predominant fouling mechanism during the pretreatment of an aqueous pectin solution by cross-flow microfiltration with membrane with nominal size of 0.44 m, at different values of transmembrane pressure, temperature, and pectin concentration. To evaluate the predominant resistive mechanism was used series resistance and permeate flux model analysis. The rejection coefficient for pectin varied from 93.4 to 97.9%. The maximum flux observed was 238.69 ± 6.48 kg m -2 h -1 at transmembrane pressure of 0.12 MPa, temperature of 50 ° C and initial pectin of 1.0 g kg -1 . The dominant restrictive mechanism observed was the cake layer formation, for all assay evaluated.