EXTRACTION AND CHARACTERISATION OF CHITIN AND CHITOSAN FOR CHROMIUM (VI) ION REMOVAL FROM WASTEWATER
EXTRACTION AND CHARACTERISATION OF CHITIN AND CHITOSAN FOR CHROMIUM (VI) ION REMOVAL FROM WASTEWATER
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Date
2014-09
Authors
ABDULKARIM, Abdulwadud Yusuf
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Abstract
This study was carried out to investigate the removal of chromium (VI) from chromate
solution using deacetylated chitin extracted from mussel shell. Mussel shells were
obtained from Gubi dam in Bauchi, Nigeria and chemical method was used to extract
chitin and then chitosan from these shells. The mussel shell contained 15.14% chitosan
as obtained from the proximate analysis. The extracted chitosan was characterised and
used for removal of Cr6+ from dichromate – water solution of 0.62 mg of Cr6+ per litre
of deionised water. The results obtained revealed that the Carbon-Nitrogen ratio of
deacetylated chitin was 5.9, with a degree of deacetylation (DDA) of 60.69% and
60.66% as calculated from elemental analysis and FTIR spectra of chitosan
respectively. The surface area of the chitosan was determined to be 2.7225 ± 0.0741
m2/g using the BET machine. The optimum chitosan dosage for chromium removal was
found to be 2.5 g at 28 oC with a Cr6+ removal of 82.3%, the time required for
equilibrium to be attained was 80 minutes. The Langmuir isotherm was the best fitted
isotherm with an R2-value of 0.983 and the adsorption process follows the pseudosecond
order kinetics with an R2-value of 0.9997, the adsorption process was
established to be reversible with an RL-value of 0.314. The free sorption energy was
(0.224 kJ/mol) which suggests the process was physical. The enthalpy of adsorption
was -67.295 kJ/mol K and the Gibbs free energies were all negative, thus the process is
spontaeneous and exothermic. The concentration of chromium (VI) ion was
successfully reduced via adsorption from the chromium solution using the extracted
chitosan from mussel shell.
Description
DEPARTMENT OF CHEMICAL ENGINEERING
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF
MASTER OF SCIENCE DEGREE IN CHEMICAL ENGINEERING.
DEPARTMENT OF CHEMICAL ENGINEERING
FACULTY OF ENGINEERING
AHMADU BELLO UNIVERSITY, ZARIA
SEPTEMBER, 2014
Keywords
EXTRACTION,, CHARACTERISATION,, CHITIN,, CHITOSAN,, CHROMIUM,, REMOVAL,, WASTEWATER