The potential of an adsorption coupled reduction process for removal of chromium(VI) was evaluated using immobilized algal consortium (of fresh water isolates, Oocystis, Nostoc, Syncoccus and Desimococcus species) through batch reactor studies. The batch sorption capacity of algae was substantially enhanced on adaptation to Cr(VI) and consortium formation (83.53 mg/g). The batch data followed Langmuir isotherm and pseudo first order kinetics. The effective applicability of the sorbent for Cr(VI) removal was tested in packed bed column reactor. At the adsorbent dosage of 1 g/L, flow rate of 3 mL/min, bed height of 20 cm and initial Cr(VI) concentration of 300 mg/L, maximum adsorption capacity of 579.2 mg/g was achieved. The possible mechanism of adsorption and reduction of Cr(VI) was explained by Fourier transform infrared spectroscopy and electron paramagnetic resonance spectroscopy analysis confirmed the reduction of Cr(VI) to Cr(III) on the sorbent surface.

Amitava Mukherjee

Centre for Nanobiotechnology

Vellore Campus

Chandra Sekaran N

Samuel J

Paul M.L

Kumari J

Ravikumar K.V.G

Fulltext

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Asian Journal of Chemistry

The adsorptive removal of Cr(VI) by alginate beads containing Cr(VI)-adapted Acinetobacter junii, Escherichia coli and Bacillus subtilis in batch and continuous packed bed column reactors was investigated. Under optimized conditions (pH 3.0; contact time, 180. min; 30°C; initial Cr(VI) concentration of 100. mg/L), 65.86. mg/g adsorption capacity was recorded in the batch study. When an adsorbent dosage of 1. g/L, a flow rate of 5. mL/min, a bed height of 20. cm, an initial Cr(VI) concentration of 300. mg/L was employed, a capacity of 657. mg/g was noted for the continuous column assay. The batch sorption data followed the Langmuir isotherm and pseudo second order kinetics. Five sorption/desorption cycles yielded 100%, 99.63%, 95.31%, 80.7% and 74.22% regeneration, respectively. Cr(VI) adsorption studies using spiked ground water, freshwater and domestic wastewater in a packed bed reactor demonstrated Cr(VI) removals of 64.8%, 55.08%, 56.86% respectively. Cr(VI) sorption on immobilized bacteria was confirmed with Fourier-transform infrared and Energy dispersive X-ray spectroscopy.

Bioresource Technology

Batch and continuous flow studies of adsorptive removal of Cr(VI) by adapted bacterial consortia immobilized in alginate beads

The current study focuses on the quantification and mechanistics of Cr(VI) biosorption with Acinetobacter junii, indigenous bacteria isolated from chromite mine sites of Sukinda valley, Orissa, India. The equilibrium sorption capacity 22.22, 13.88, 6.94mg of Cr(VI)g -1 of biomass was obtained for logarithmic phase, stationary phase and heat killed biomass respectively at optimum sorption conditions (pH: 2.0, contact time: 120min, temperature: 27°C, initial Cr(VI) concentration: 100mgL -1, biosorbent dosage: 2gL -1). The Langmuir isotherm model and pseudo first order (Lagergren kinetic model) were observed to hold good for the bio-sorbents. Three subsequent sorption/desorption cycles yielded 54.9, 38.4 and 34.5% regeneration of the biosorbent indicating an irreversible chromium(VI) binding property of the sorbent system. The mechanistic aspects of sorption by heat killed and log phase biomass were compared using FTIR and SEM techniques. The number of binding sites on biomass surface measured by acid/base titration (215μmolg -1 and 99μmolg -1 for logarithmic phase and heat killed biomass respectively) corroborated with the observations made by batch sorption studies. Detailed surface characterization studied through FT-IR, SEM, EDX and zeta potential measurement provided evidence for sorption through oxyanionic binding to the cell surface. The EPR spectroscopy revealed the reduction of Cr(VI) to Cr(V) on the biomass surface upon Cr(VI) sorption. © 2012 Elsevier B.V.

Chemical Engineering Journal

Comparative kinetics, equilibrium, thermodynamic and mechanistic studies on biosorption of hexavalent chromium by live and heat killed biomass of Acinetobacter junii VITSUKMW2, an indigenous chromite mine isolate

Indigenous isolates from the waters of chromite mining sites at Sukinda Valley, Orissa, India, showed a considerable enhancement in Cr (VI) bioreduction rate through adaptation and consortia development. On the basis of 16S-rRNA sequencing, these isolates were identified as Bacillus subtilis VITSUKMW1, Acinetobacter junii VITSUKMW2, and Escherichia coli VITSUKMW3. The native isolates showed a high tolerance at 500-1000 mg L-1 of Cr (VI). An increase in the reduction rate from 0.199-0.477 mg L-1 h-1 to 0.5-1.16 mg L-1 h-1 at 5-20 mg L -1 of initial Cr (VI) concentration was achieved by the adapted isolates. An increase in the growth rate and Cr (VI) reduction rate [0.86-2.6813 mg L-1 h-1 at 5-100 mg L-1 of initial Cr (VI) concentration] was observed in the ternary consortium of adapted isolates. The FT-IR spectra revealed the active participation of the bacterial surface groups in the reduction. The development of sequential processes (native → adapted → consortia) employing Cr (VI) tolerant isolates, proves to be a potential bioremediation strategy for specific chromite mine sites.

Industrial & Engineering Chemistry Research

Hexavalent Chromium Bioremoval through Adaptation and Consortia Development from Sukinda Chromite Mine Isolates

The removal of Cd (II) from industrial wastewater by macrofungus Pleurotus platypus was investigated in a fixed bed column. Experiments were conducted to study the effect of important parameters such as bed depth (5-15cm) and flow rate (5-15mlmin-1). The bed depth service time model (BDST) fitted well with the experimental data and the adsorption capacity (N0) estimated from this model was 2418.12mgL-1. The effect of co-ions on adsorption of cadmium (II) was analyzed as single and multimetal systems. The breakthrough and exhaustion points were found to be earlier for biosorption of cadmium (II) in the presence of co-ions. The biosorbent was employed for the treatment of industrial effluent in a continuous column mode and its reusability was assessed. The column was regenerated by eluting cadmium (II) using 0.01M HCl and the adsorbent was reused for three sorption-desorption cycles without considerable loss in biosorption capacity. In the three cycles of biosorption, about 3.6L of industrial effluent could be treated to reach the Cd (II) standard (0.1mgL-1) established by the Central Pollution Control Board (CPCB). P. platypus proved to be the potential biosorbent for the removal of Cd (II) from industrial effluents. © 2011 Elsevier B.V.

Journal	Asian Journal of Chemistry
Publisher	Asian Journal of Chemistry
ISSN	0970-7077
Open Access	Yes