Biosorption of Cr (VI) ions from electroplating industrial effluent using immobilized
Aspergillus niger
biomass
S. Chhikara*
and R. Dhankhar
Ecology Laboratory,
Department of Bio-Sciences, M.D. University, Rohtak - 124
001, India
(Received:
January 01, 2007; Revised received: June 05, 2007 ;
Accepted: July 10, 2007)
Abstract:? A fungus, Aspergillus
niger was chemically treated with 0.1 M H2SO4
and 0.1N NaOH to form biosorbent
and it was immobilized in calcium alginate beads.? The biosorption
capacity of immobilized biosorbents for Cr (VI) was
found to depend on pH, contact time, biosorbent dose
and initial concentration of Cr(VI). The maximum uptake
of Cr (VI) was 92.5, 95.9 and 98.4 mg respectively at a pH of 1.5 and with an
increase in pH up to 10.5 the metal uptake decreased gradually upto 38.75, 50.19 and 65.28 mg respectively for acid
treated, untreated and base treated fungal biosorbents.
Increase in biosorbent dose up to 1g of biomass and
contact time up to 60 min resulted in an increase in biosorption
from 19.6, 15.6 and 26.1 mg at a biosorbent dose of
0.1g 100 ml-1 to 92.45, 95.7 and 98.52 mg at a biosorbent
dose of 1.0 g 100 ml-1 and then further increase in adsorbent dose
and contact time did not resulted in more Cr (VI) adsorption by per unit weight
of biosorbent. The value of Kad (adsorption
rate constant) revealed the pseudo-first order nature of biosorption.
The percentage metal uptake by the biosorbent was
found to decrease upto 62.33, 52.67 and 83.5 percent
respectively for acid treated, untreated and base treated fungal biosorbents at the 300? mgl-1
Cr (VI) ion concentration. The resulted data was found to fit well in langmuir model
of adsorption isotherm with a high value of correlation coefficient. The value
of Qmax, b (Langmuir constants),? RL
(separation factor) and DG (Gibb?s free energy) revealed the favourable nature of adsorption.? The biosorbed metal
was eluted from the biosorbent by using 0.1M H2SO4
as elutant. Immobilized biosorbent
can be reused for, five consecutive biosorption/desorption
cycles without apparent loss of efficiency after its reconditioning. The biosorbent was found to perform well in the electroplating industrial
effluent.
Key words: ? Aspergillus niger,
Adsorption, Immobilization,
Isotherm, Chromium
PDF of full length paper is available with author (chhikaras14@rediffmail.com)
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