Drying
is essential in the production of biobutanol. In this work,
the dynamics of water adsorption from butanol–water vapor mixtures
in a fixed bed column were investigated. The biosorbent used in this
system was derived from a cellulosic material oat hull. Water adsorption
breakthrough curves obtained from the biosorbent packed column were
simulated by the Bohart–Adams model and Klinkenberg model.
The Klinkenberg model provided a better simulation of the experimental
data in comparison with the Bohart–Adams model. The mass transfer
coefficient and mass transfer resistances were investigated from the
modeling results. The results indicated that the rate of water adsorption
was controlled by internal mass transfer resistance. The water adsorption
on the biosorbent was visualized with the aid of microscope imaging.
This study reveals that water saturated oat hull based biosorbent
was regenerated and reused successfully.
Polyelectrolyte hydrogel fibers can
mimic the extracellular matrix
and be used for tissue scaffolding. Mechanical properties of polyelectrolyte
nanofibers are crucial in manipulating cell behavior, which metal
ions have been found to enable tuning. While metal ions play an important
role in manipulating the mechanical properties of the fibers, evaluating
the mechanical properties of a single hydrated hydrogel fiber remains
a challenging task and a more detailed understanding of how ions modulate
the mechanical properties of individual polyelectrolyte polymers is
still lacking. In this study, dark-field microscopy and persistence
length analysis help directly evaluate fiber mechanics using electrospun
fibers of poly(acrylic acid) (PAA), chitosan (CS), and ferric ions
as a model system. By comparing the persistence length and estimated
Young’s modulus of different nanofibers, we demonstrate that
persistence length analysis is a viable approach to evaluate mechanical
properties of hydrated fibers. Ferric ions were found to create shorter
and stiffer nanofibers, with Young’s modulus estimated at a
few kilopascals. Ferric ions, at low concentration, reduce the Young’s
modulus of PAA and PAA/CS fibers through the interaction between ferric
ions and carboxylate groups. Such interaction was further supported
by nanoscale infrared spectroscopy studies of PAA and PAA/CS fibers
with different concentrations of ferric ions.
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