7.3 Experiment
141
HO
HO
OH
O
HO
OH
O
NH 2
O
OH
O
NH 2
HO
OH
O
HO
HO
O
N
O
HO
OH
O
NH 2
O
OH
O
HO
OH
O
C
H
O
H
NH 2
CH
CH
HO
HO
OH
O
HO
OH
O
NH 2
O
HO
OH
O
N
N
CH
CROSSLINKING REACTION
CHITOSAN
C
O
H
CH
GLYOXAL
OH
O
N
N
H
H
N
H
N
H
H
HO
HO
O
N
O
HO
OH
O
NH 2
O
OH
O
HO
OH
O
CH
CH
HO
HO
OH
O
HO
OH
O
NH 2
O
HO
OH
O
N
N
CH
CH
O
N
N
H
H
N
H
N
H
H
n
O
N
H
H
N
H
N
H
H
n
GRAFTING
REACTION
DIETHYLENETRIAMINE
Fig. 7.1 Schematic illustration of the arrangement suggested for the cross-linking and grafting of
chitosan beads
7.3.4.2 Determining the Stability of the Beads/Perle
In acid solution, the firmness of the different set beads was tested using a 100 mL
0.1 M HCl mixture. 20.0 g of the produced beads, however, were put separately in
250 mL flasks containing the acid solution; the pH of the mixture in the different
flasks was changed from pH 2 to pH 5, respectively. The flasks were transferred to
a 24 h shaker at a spinning rate of 120 rpm. The solvent was drained off, and the
weight of the beads left in the flask was obtained.
7.3.4.3 Determination of Grafting Degree and pKa
In determining the amine concentration of beads, a standard titration procedure implemented by Osifo et al. [18] was employed. Briefly, weighed and blended 20.0 g of the
grafted cross-linked beads, the grounded beads were combined with 100 mL distilled