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Aleksandar Zdujić,Katarina Trivunac,Biljana Pejić,Marija Vukčević,Mirjana Kostić,Milan Milivojević 한국섬유공학회 2021 Fibers and polymers Vol.22 No.1
Ca-alginate particles (CA) and alginate-impregnated hemp fibers (AH) (both, as prepared, dried, and rehydrated)were used as adsorbents for removal of Ni (II) ions from water. Adsorption was examined in the batch system andexperimentally obtained data were analyzed by both linear and nonlinear curve fitting using pseudo-first and pseudo-secondorderrate, as well as Langmuir, Freundlich, and Sips equations. The concentration of Ni (II) ions was measured by atomicabsorption spectrophotometry, while the Fourier transform infrared spectroscopy was used for characterization of adsorbentsurface, before and after the adsorption. Although all tested samples showed similar adsorption capacities of 12 mg/g, it wasfound that rehydration improves adsorption characteristics of AH and increases the removal efficiency above 90 %. Adsorption of Ni (II) ions can be sufficiently described by both kinetic models and Sips isotherm equation, and this relativelyfast process presumably occurs through the mechanism of physisorption and ion-exchange. The obtained results proved thatCa-alginate particles and alginate-impregnated hemp fibers have good potential to reduce nickel concentrations in a costeffectiveand efficient manner.
Milica Veljkovic,Relja Stepanovic,Katarina Banjanac,Marija Ćorović,Ana Milivojevic,Milica Simović,Milan Milivojević,Dejan Bezbradica 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-
Within this study, the investigation of potential selective immobilization of fructosyltransferase (FTase) derived from Aspergillus aculeatus (from commercial enzyme preparation Pectinex® Ultra SP-L) onto the polystyrenic macroporous resin Purolite® A109 and its further utilization for the synthesis of a highly valuable group of prebiotic compounds named fructo-oligosaccharides (FOS), was performed. The obtained results suggest that partial purification of fructosyltransferase from complex enzyme mixture with predominant pectinase activity (ratio of activity immobilization yields around 20.0) occurred by performing a simple immobilization protocol, provided that immobilization lasted for 5 h using an enzyme concentration of 50 mg g−1 of support under slightly acidic conditions (pH 6.0). Immobilized preparation was thereafter successfully utilized for FOS synthesis (56–59 % FOS of total sugars) in both a batch and air-lift reactor system. Operational stability study proved the exceptionally high potential of immobilized preparation for reproducible and cost-effective application, since 90 % of initial activity was preserved after ten consecutive reaction cycles. Thereafter, a prospectus for continuous production of FOS in the air-lift reactor was assayed. Achieved yields, 53 % FOS of total sugars for at least 9 h, indicated the great suitability of the obtained immobilized preparation for application in large-scale systems.