48
3 Chitin
8 kg of 4% vol of sodium hydroxide used per kg of chitin produced; however, no
data was provided for the amount used for chitosan production.
Use of proteolytic enzymes in the deproteinization process is an alternative; however, much of this is still in the research stage and is yet to be commercialized. The
use of microbial extraction could potentially eliminate the need for sodium hydroxide
in the production of chitin. However, the higher concentration is used in the deacetylation process for production of chitosan. An alternative or accompanying process
could be enzymatic deacetylation using the enzyme deacetylase. This is presently
under research, and the mechanism of action and specificity of this enzyme is still
under study. Biotechnology-based deacetylation of chitosan would be a great leap in
a truly green process for chitosan production.
3.6.5 Acid Usage and Disposal
In the chemical process, the acid is mainly used in the demineralization stage. According to data produced by Mahtani Chitosan company (Munoz et al. 2018), to produce
1 kg of chitin 8 kg of hydrochloric acid at 32% concentration is used. In the lactic acid
fermentation process, lactic acid is produced by the bacteria and poses less environment adverse effect. Since the acid unlike the alkali actually reacts with the calcium
carbonate, it is not recovered, and it is converted into calcium chloride, water and
carbon dioxide, the products of the reaction between hydrochloric acid and calcium
carbonate. The impact of the hydrochloric acid used is therefore the carbon dioxide
emission resulting from the process.
3.6.6 CO 2 Emission
In the demineralization stage, carbon dioxide is emitted as the calcium carbonate
reacts with hydrochloric acid to form calcium chloride water and carbon dioxide as
shown in Eq. (3.1).
2HCl + CaCO 3 → CaCl 2 + H 2 O + CO 2
(3.1)
CO 2 emitted from organic degradation of the shrimp and crab shell waste is rated
as zero, while CO 2 emission from clearing of land for building of chitosan factory
and the increased pressure on clearing of land for growing of plant-based animal
feed such as soybean and barley is rated as GWP-100 (global warming potential) of
1. This is because with organic degradation the carbon being emitted is that which
was removed recently during formation to the shells, while that from clearing of
long-standing plants at a much larger scale had more impact on CO 2 emission.
Approximately, 0.7 kg of CO 2 is released per 1 kg of chitin produced during the
acid mineralization process. This means the production process is resulting in CO 2
3 Chitin
8 kg of 4% vol of sodium hydroxide used per kg of chitin produced; however, no
data was provided for the amount used for chitosan production.
Use of proteolytic enzymes in the deproteinization process is an alternative; however, much of this is still in the research stage and is yet to be commercialized. The
use of microbial extraction could potentially eliminate the need for sodium hydroxide
in the production of chitin. However, the higher concentration is used in the deacetylation process for production of chitosan. An alternative or accompanying process
could be enzymatic deacetylation using the enzyme deacetylase. This is presently
under research, and the mechanism of action and specificity of this enzyme is still
under study. Biotechnology-based deacetylation of chitosan would be a great leap in
a truly green process for chitosan production.
3.6.5 Acid Usage and Disposal
In the chemical process, the acid is mainly used in the demineralization stage. According to data produced by Mahtani Chitosan company (Munoz et al. 2018), to produce
1 kg of chitin 8 kg of hydrochloric acid at 32% concentration is used. In the lactic acid
fermentation process, lactic acid is produced by the bacteria and poses less environment adverse effect. Since the acid unlike the alkali actually reacts with the calcium
carbonate, it is not recovered, and it is converted into calcium chloride, water and
carbon dioxide, the products of the reaction between hydrochloric acid and calcium
carbonate. The impact of the hydrochloric acid used is therefore the carbon dioxide
emission resulting from the process.
3.6.6 CO 2 Emission
In the demineralization stage, carbon dioxide is emitted as the calcium carbonate
reacts with hydrochloric acid to form calcium chloride water and carbon dioxide as
shown in Eq. (3.1).
2HCl + CaCO 3 → CaCl 2 + H 2 O + CO 2
(3.1)
CO 2 emitted from organic degradation of the shrimp and crab shell waste is rated
as zero, while CO 2 emission from clearing of land for building of chitosan factory
and the increased pressure on clearing of land for growing of plant-based animal
feed such as soybean and barley is rated as GWP-100 (global warming potential) of
1. This is because with organic degradation the carbon being emitted is that which
was removed recently during formation to the shells, while that from clearing of
long-standing plants at a much larger scale had more impact on CO 2 emission.
Approximately, 0.7 kg of CO 2 is released per 1 kg of chitin produced during the
acid mineralization process. This means the production process is resulting in CO 2