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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 12, No. 5, 2015, pp. 1591-1602
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Bioline Code: st15148
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 12, No. 5, 2015, pp. 1591-1602
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Chromium(III) biosorption onto spent grains residual from brewing industry: equilibrium, kinetics and column studies
Ferraz, A.I.; Amorim, C.; Tavares, T. & Teixeira, J.A.
Abstract
The use of industrial wastes for wastewater
treatment as a strategy to their re-use and valorisation may
provide important advances toward sustainability. The
present work gives new insights into heavy metal biosorption
onto low-cost biosorbents, studying chromium(III)
biosorption onto spent grains residual from a Portuguese
brewing industry both in batch and expanded bed column
systems. Experimental studies involved unmodified spent
grains and spent grains treated with NaOH. Metal uptake
followed a rapid initial step, well described by the pseudosecond-
order kinetic model up to 2–7 h, indicating
chemisorption to be the rate-limiting step. Beyond this
period intraparticle diffusion assumed an important role in
the uptake global kinetics. The best fit for equilibrium data
was obtained using the Langmuir model, with unmodified
spent grains having the higher maximum uptake capacity
(qmax = 16.7 mg g-1). In open system studies, using
expanded bed columns, the best performance was also
achieved with unmodified spent grains: Breakthrough time
(C/Ci = 0.25) and total saturation time (C/Ci = 0.99)
occurred after 58 and 199 h of operation, corresponding to
the accumulation of 390 mg of chromium(III), 43.3 % of
the total amount entering the column. These results suggest
that alkali treatment does not improve spent grains uptake
performance. Changes in biomass composition determined
by Fourier transform infrared spectroscopy suggested
hydroxyl groups and proteins to have an important role in
chromium(III) biosorption. This study points out that
unmodified spent grains can be successfully used as lowcost
biosorbent for trivalent chromium.
Keywords
Breakthrough curves; Heavy metals; Low-cost biosorbents; Waste valorisation
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