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In this work, the partition coefficients of Cephalexin in aqueous two-phase systems containing PEG [poly(ethylene glycol)] 4000, 10000 and K2HPO4, Na3Citrate (C6H5Na3O7 5, 5H2O) have been measured. The experimental data were obtained in a wide range of temperatures, (28.2 to 37.2) °C. The effects of temperature, pH, polymer concentration, polymer molecular weight, and salt concentration on the partitioning of Cephalexin were also studied. The results showed that salt concentration has a large effect on the partition coefficient, and temperature has an almost negligible effect. The Chen−NRTL Gibbs energy model was used to correlate the experimental results.
According to the
great potential of zero-valent iron nanoparticle
applications in the environmental, medical, chemical, packaging and
many other industries, there is still a need to tailor their production
methods. This study reports the production of a hybrid nanostructure
based on iron nanoparticles (INPs) produced in/on montmorillonite
(MMT) nanoclays as an oxygen scavenger and barrier additive in polymeric
packaging materials of oxygen-sensitive products. INPs and MMT were
demonstrated to have effective mutual interactions in which the MMT
host played a chemophysical trapping role for iron particles, causing
smaller particles around 10 nm with 6.2 g/m
2
higher specific
surface area by limiting particle growth and agglomeration. In return,
the embedding of primary iron cations in/on clays and growth of these
particles during the reduction reaction pushed the clay layers out
and helped further clay intercalation–exfoliation. Effective
study of solvent and primary cation (Fe
2+
/Fe
3+
) types showed different preferences in interacting with natural
and alkylammonium-modified MMT, resulting in the different site selection.
Fe
2+
cations preferred to migrate to the interlayer space,
whereas Fe
3+
cations tended to bond to the clay surface.
The obtained results in this study suggest tailoring the ultimate
oxygen scavenging capacity, shelf life, and migration properties of
a hybrid nanoparticle according to the application requirements.
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