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Bioleaching kinetics of a spent refinery catalyst using Aspergillus niger at optimal conditions

Paper ID Volume ID Publish Year Pages File Format Full-Text
3523 173 2012 10 PDF Available
Title
Bioleaching kinetics of a spent refinery catalyst using Aspergillus niger at optimal conditions
Abstract

The kinetics of bioleaching of Mo, Ni, and Al from spent hydrocracking catalyst, using Aspergillus niger was studied. The four most effective bioleaching variables were selected in accordance with the Plackett–Burman design and were further optimized via central composite design (CCD). The optimal values of the variables for maximum multi-metal bioleaching were as follows: particle size 150–212 μm, sucrose 93.8 g/L, pulp density 3% w/v, and pH 7. The maximum metal recoveries corresponding to these conditions were 99.5 ± 0.4% Mo, 45.8 ± 1.2% Ni, and 13.9 ± 0.1% Al. The relatively low Ni extraction was attributed to the precipitation of Ni in the presence of oxalic acid. Under the optimal conditions, the fungus growth was found to be higher in the presence of spent catalyst than that in the catalyst-free medium. Determinations of the organic acid concentration showed noticeable variation during bioleaching, particularly for gluconic acid. Accordingly, a modified form of shrinking core model was used to take these variations into account. The predictions by the model showed good consistency with the experimental results, suggesting that diffusion of bioleaching agent through the solid matrix was the rate-controlling step.

► The kinetics of bioleaching of metals from a spent catalyst, using Aspergillus niger was studied. ► Most effective bioleaching variables were selected in accordance with the Plackett–Burman design. ► Determinations of organic acid concentration showed noticeable variation during bioleaching. ► Predictions by the model showed that diffusion through the solid matrix is the rate-controlling step.

Keywords
Bioleaching; Waste treatment; Extraction kinetics; Spent catalyst; Optimization; Filamentous fungi
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biochemical Engineering Journal - Volume 67, 15 August 2012, Pages 208–217
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
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