3.7 Applications
53
Transparent films are in high demand in the packaging industry. From edible food
packaging to transparent films used as screen protectors, there is huge demand for
such films. Presently, petroleum-based polymers such as polyethylene offer low cost,
easily mass produced and conveniently sourced option. For chitin to compete with
this, there needs to be a well-established low-cost production process since chitin
already meets the other application demands. Off all the biopolymers available, chitosan and other chitin derivatives demonstrate the most desirable properties suitable
for production of transparent packaging films.
3.7.2 Water Treatment
It can be said that one of the best explored applications of chitosan so far is in water
treatment. Industrially produced chitosan is used in wastewater treatment for removal
of metals and dyes. It also acts as a flocculant and coagulant and in immobilization
of microorganisms. This multiple role makes it very useful in wastewater treatment.
Chitosan has the ability to remove heavy metals, lipids and overall decrease in turbidity of water. Applicability of chitosan in water treatment can be attributed to its
antimicrobial properties, metal chelation and adsorption properties. The antimicrobial property is further discussed in another subsection. The absorption process is
widely used in water treatment and is well explored. Chitosan is a commonly used
adsorbent alongside others such as cellulose and guarana.
The amine group on the deacetylated chitin plays the role of binding to metals,
and this results in the formation of a chitosan–metal complex with multiple metal
molecules binding to one chitosan molecule (Shahidi et al. 1999). The amine group
also has high capability to bind with minerals, lipids and proteins which gives chitosan
its versatility compared to chitin. Since this metal-chelating property is dependent
on the availability of the amine group on the polymer for bonding, the higher the
degree of deacetylation, the better the chitosan polymer’s metal-chelating property.
It is important that a water treatment agent is low cost, non-toxic and biodegradable
and can be used at low quantities. Chitosan at a concentration of 0.2 g in 100 ml
of water can reduce total dissolved solid content by up to 12.87%. Chitosan also
achieved significant reduction in turbidity and conductivity and overall makes water
suitable for drinking at relatively low concentration required (Al-Manhel et al. 2018).
3.7.3 Antimicrobial
A full understanding of the mechanism by which chitosan inhibits bacterial cell is
still pending. It is believed that it does this by means of blocking the surface of the
bacterial cell by chemically binding to the lipids present on the surface. This prevents
the bacteria from taking up nutrients necessary for growth and survival and eventually
leads to cell death or inhibition. This is made possible by the reactive binding of the
53
Transparent films are in high demand in the packaging industry. From edible food
packaging to transparent films used as screen protectors, there is huge demand for
such films. Presently, petroleum-based polymers such as polyethylene offer low cost,
easily mass produced and conveniently sourced option. For chitin to compete with
this, there needs to be a well-established low-cost production process since chitin
already meets the other application demands. Off all the biopolymers available, chitosan and other chitin derivatives demonstrate the most desirable properties suitable
for production of transparent packaging films.
3.7.2 Water Treatment
It can be said that one of the best explored applications of chitosan so far is in water
treatment. Industrially produced chitosan is used in wastewater treatment for removal
of metals and dyes. It also acts as a flocculant and coagulant and in immobilization
of microorganisms. This multiple role makes it very useful in wastewater treatment.
Chitosan has the ability to remove heavy metals, lipids and overall decrease in turbidity of water. Applicability of chitosan in water treatment can be attributed to its
antimicrobial properties, metal chelation and adsorption properties. The antimicrobial property is further discussed in another subsection. The absorption process is
widely used in water treatment and is well explored. Chitosan is a commonly used
adsorbent alongside others such as cellulose and guarana.
The amine group on the deacetylated chitin plays the role of binding to metals,
and this results in the formation of a chitosan–metal complex with multiple metal
molecules binding to one chitosan molecule (Shahidi et al. 1999). The amine group
also has high capability to bind with minerals, lipids and proteins which gives chitosan
its versatility compared to chitin. Since this metal-chelating property is dependent
on the availability of the amine group on the polymer for bonding, the higher the
degree of deacetylation, the better the chitosan polymer’s metal-chelating property.
It is important that a water treatment agent is low cost, non-toxic and biodegradable
and can be used at low quantities. Chitosan at a concentration of 0.2 g in 100 ml
of water can reduce total dissolved solid content by up to 12.87%. Chitosan also
achieved significant reduction in turbidity and conductivity and overall makes water
suitable for drinking at relatively low concentration required (Al-Manhel et al. 2018).
3.7.3 Antimicrobial
A full understanding of the mechanism by which chitosan inhibits bacterial cell is
still pending. It is believed that it does this by means of blocking the surface of the
bacterial cell by chemically binding to the lipids present on the surface. This prevents
the bacteria from taking up nutrients necessary for growth and survival and eventually
leads to cell death or inhibition. This is made possible by the reactive binding of the