100
5 Biopolymer Chitosan Membranes Prepared from Fishery Waste …
water loss [19]. The second step began with a weight loss of 38% at 200 up to 350 °C.
This weight loss is due to the degradation of the saccharide chains, depolymerisation
and decomposition of the adsorbent acetylated and deacetylated units [20]. In the
third step, weight loss above 400 °C was 54%. The disintegration of non-cross-linked
chitosan membrane is observed in this step.
When glutaraldehyde was cross-linked with chitosan membrane, a weight loss of
5% was noted at the first step of breakdown and at temperatures around 34–141 °C.
The second step began at 227 °C and proceeded with a weight loss of 31% up to
330 °C. There was a weight loss of 15% over 500 °C in the third step. This weight
loss in the first, second and third steps relates to the removal of surface water, the
depolymerisation and the decomposition of the acetylated and deacetylated adsorbent
groups and the decomposing of the cross-linked chitosan membrane [21, 22].
5.3.1.4 Outcome of SEM Analysis
CS and XCS morphology were examined employing electron microscope (SEM)
scanning. Sem scans with 50× magnification following EDX findings are shown
in Fig. 5.3a, b; glutaraldehyde cross-linking on the layer of the chitosan membrane
contributes to a smoothness of the layer suggesting that glutaraldehyde is strongly
attached to the layer of the membrane. The EDX finding indicated several important
elements in the membranes, and the elements found in CS (N, C, H and O) were
also available in XCS only that the percentage mass of N was decreased following
cross-linking, and this may well be predicted because some of the chitosan amine
group is used in the cross-linking interaction. Consequently, owing to glutaraldehyde
cross-linking to chitosan, XCS has been confirmed to generate enough of C, O and
H. The graphical illustration of the method of cross-linking is shown in Fig. 5.4,
In this illustration, glutaraldehyde binds selectively to nitrogen and allows covalent
links across chains.
5.3.1.5 The Influence of pH PZC
The influence of pH can be explained in view of the adsorbent pH PZC . CS ‘pHpzc
was noted to be 4.62, whereas XCS’s was determined to be 4.93, accordingly. The
rise in pHpzc from 4.62 for CS to 4.93 for XCS can be attributed to a reduction in
acidic groups owing to glutaraldehyde interaction and amide-forming acid groups
that lower total acidity. PH PZC is the pH solution where the maximum adsorbent
surface charge measured is zero [16]. If an adsorbent is put in a solution with pH <
pHpzc of the adsorbent, certain functional groups are protonated and the adsorbent
behaves as a positive charged poly-matrix [23]. The negatively charged ions available
in the solution are attracted by this. Metal ions, nevertheless, are generally charged
positively except the oxyanions of other metals such as arsenate and chromate, which
are charged negative. At this point, those negative ions are attracted by the adsorbent.
5 Biopolymer Chitosan Membranes Prepared from Fishery Waste …
water loss [19]. The second step began with a weight loss of 38% at 200 up to 350 °C.
This weight loss is due to the degradation of the saccharide chains, depolymerisation
and decomposition of the adsorbent acetylated and deacetylated units [20]. In the
third step, weight loss above 400 °C was 54%. The disintegration of non-cross-linked
chitosan membrane is observed in this step.
When glutaraldehyde was cross-linked with chitosan membrane, a weight loss of
5% was noted at the first step of breakdown and at temperatures around 34–141 °C.
The second step began at 227 °C and proceeded with a weight loss of 31% up to
330 °C. There was a weight loss of 15% over 500 °C in the third step. This weight
loss in the first, second and third steps relates to the removal of surface water, the
depolymerisation and the decomposition of the acetylated and deacetylated adsorbent
groups and the decomposing of the cross-linked chitosan membrane [21, 22].
5.3.1.4 Outcome of SEM Analysis
CS and XCS morphology were examined employing electron microscope (SEM)
scanning. Sem scans with 50× magnification following EDX findings are shown
in Fig. 5.3a, b; glutaraldehyde cross-linking on the layer of the chitosan membrane
contributes to a smoothness of the layer suggesting that glutaraldehyde is strongly
attached to the layer of the membrane. The EDX finding indicated several important
elements in the membranes, and the elements found in CS (N, C, H and O) were
also available in XCS only that the percentage mass of N was decreased following
cross-linking, and this may well be predicted because some of the chitosan amine
group is used in the cross-linking interaction. Consequently, owing to glutaraldehyde
cross-linking to chitosan, XCS has been confirmed to generate enough of C, O and
H. The graphical illustration of the method of cross-linking is shown in Fig. 5.4,
In this illustration, glutaraldehyde binds selectively to nitrogen and allows covalent
links across chains.
5.3.1.5 The Influence of pH PZC
The influence of pH can be explained in view of the adsorbent pH PZC . CS ‘pHpzc
was noted to be 4.62, whereas XCS’s was determined to be 4.93, accordingly. The
rise in pHpzc from 4.62 for CS to 4.93 for XCS can be attributed to a reduction in
acidic groups owing to glutaraldehyde interaction and amide-forming acid groups
that lower total acidity. PH PZC is the pH solution where the maximum adsorbent
surface charge measured is zero [16]. If an adsorbent is put in a solution with pH <
pHpzc of the adsorbent, certain functional groups are protonated and the adsorbent
behaves as a positive charged poly-matrix [23]. The negatively charged ions available
in the solution are attracted by this. Metal ions, nevertheless, are generally charged
positively except the oxyanions of other metals such as arsenate and chromate, which
are charged negative. At this point, those negative ions are attracted by the adsorbent.