Removal of copper and iron by amidoxime modified poly (Acrylonitrile-g-microcrystalline cellulose)
Heavy metal ions that not treated from many industries have been severely polluted the environment and can caused serious impact to human health. The discharge of heavy metal effluents into water sources can generate accumulation of toxicity and unwanted contaminants. Hence, proper treatment of h...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/103985/1/MOHAMMAD%20BIN%20ABDULLAH%20-IR.pdf |
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| Summary: | Heavy metal ions that not treated from many industries have been severely polluted the
environment and can caused serious impact to human health. The discharge of heavy
metal effluents into water sources can generate accumulation of toxicity and unwanted
contaminants. Hence, proper treatment of heavy metal ions from industrial wastewater
is a main environmental pollution concern for consideration. The adsorption process
become an alternate approach to eradicate heavy metal ions. This study investigated the
polymer-based adsorbent; amidoxime modified poly(acrylonitrile-g-microcrystalline
cellulose) that was used to remove selected heavy metal ions (copper, Cu2+ and iron,
Fe2+) by adsorption method. The poly(acrylonitrile-g-microcrystalline cellulose) was
synthesised by redox polymerisation of acrylonitrile (AN) and microcrystalline cellulose
(MCC) monomer and further modified chemically with amidoxime to produce AO
modified poly(AN-g-MCC) adsorbent. Then, single batch adsorption experiments for
each heavy metal, Cu2+ and Fe2+ were executed at different working conditions such
adsorbent dosage, pH, initial metal ion concentrations and soaking time. Besides, batch
mode of adsorption for binary heavy metal ions onto AO modified poly(AN-g-MCC)
was studied.
The synthesised of poly(AN-g-MCC) produced the highest yield (96%) at polymer ratio
93:7 (AN:MCC). The characterisations result of polymerised polymer; Fourier transform
infrared (FTIR) confirmed the successful of polymerisation due to the presence of
absorption peaks that were assigned to the C≡N and –COOH functional groups on the
spectra. Scanning Electron Microscope (SEM) showed the appearance of AN bead onto
MCC surface. The thermogravimetric (TG) analysis recommended that the thermal
stability of poly(AN-g-MCC) was lower as compared with MCC. The poly(AN-g-MCC)
where further chemically altered with hydroxylamine hydrochloride. The FTIR spectra
verified the successful conversion of C≡N into amidoxime groups. The microanalysis
presented that the overall trend of elemental percentage for AO modified poly(AN-g-
MCC) copolymers were increase of nitrogen and hydrogen elements. To further confirm
the quantity of amidoxime functional group in modified polymer, the amine capacity test
was conducted. The ratio of 93:7 has the highest amount of amine capacity (12.42
mmol/g), followed by 90:10 (11.45 mmol/g) and the low amount of amine capacity at
feed mole ratios 95:5 (10.5 mmol/g) and 97:3 (9.75 mmol/g).
The single batch system of the adsorption progression for the elimination of Cu2+ and
Fe2+ were conducted by varying the pH (2 -12), adsorbent dosage (0.2 – 1.0 g), initial
metal ion concentration (50-150 mg/L) and contact time (2-100 minutes). The maximum
removal percentage for Cu2+ and Fe2+ were 99.5% and 96.4%, respectively at pH 7. The
effect of adsorbent dosage showed the 1.0 g/L of adsorbents, result the highest
percentage of Cu2+ (99.8%) and Fe2+ (88.63%) correspondingly. The highest percentage
removal of Cu2+ and Fe2+ were 99.5% and 95.8% respectively at 50 mg/L.
Meanwhile at 60 minutes the percentage removal become maximum for Cu2+ (89.0%)
and Fe2+ (87.5%). The experiment data were examined using equilibrium and kinetic
studies. Equilibrium data was well fitted with Freundlich isotherms. The Freundlich
isotherms showed good agreement for the adsorption of Cu2+ (R2 of 0.9493) with the
maximum adsorption capacities of 120.58 mg/g. The adsorption of Fe2+ also satisfied
with Freundlich isotherms (R2 of 0.9558) with maximum adsorption capacities of 235.91
mg/g.
In binary system, the effects of adsorbent dosage (0.2-1.2 g), pH (3,5, and 9), initial
adsorbate concentration (20-100 mg/L) and contact time (0-100 minutes) on equilibrium
adsorption capacity were determined. An increase in adsorbent dosage increased the
removal of metal ions in binary system. The Cu2+ and Fe2+uptake was more favourable
at pH 9 in binary system. The percentage removal of Cu2+ at 100 mg/L of binary solution
was 91.13 %, whereas the Fe2+ ions uptake was only 84.51%. Both heavy metal ions
reached their equilibrium at 60 min and after that the removal of heavy metal ions
become almost constant. Extended Langmuir model and extended Freundlich model
provide a suitable description of the experimental binary data. The comparison of the
single and binary isotherms reveals an antagonistic interaction (occurred when the
adsorption capacity of an adsorbent reduces in a solution containing other components)
between the Cu2+ and Fe2+. In addition, pseudo-second-order model was found suitable
for the description of adsorption kinetic for both metal ions onto AO modified poly (ANg-
MCC), for both single and binary system, signifying chemisorption between adsorbent
and heavy metals molecule.
Based on experimental findings, AO modified poly (AN-g-MCC) polymer is a promising
functional regenerable adsorbent with high capacity to remove heavy metal (for single
and binary system) from liquid environment. |
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