Techno Press
Techno Press

Advances in Environmental Research   Volume 6, Number 2, June 2017, pages 095-111
Valorization of swine manure into low cost activated carbons capable of Cr(VI) removal
Lenia Gonsalvesh, Grazyna Gryglewicz, Robert Carleer and Jan Yperman

Abstract     [Full Text]
    The valorization of swine manure samples, i.e., de-watered cake (SMc) and solid digestate (SMd), in products with beneficial value, i.e. low cost activated carbons (ACs), is studied. For this purpose slow pyrolysis and steam activation at three different duration times are applied. Additionally, the obtained ACs are characterized and tested towards removal of Cr(VI) from aqueous solutions. It is revealed that BET surface area varies in the range of 236-267 m2/g for ACs prepared from SMc sample and in the range of 411-432 m2/g for ACs prepared from SMd sample. Despite the low determined surface area of prepared ACs, a high total Cr removal capacity is observed occurring through a \"coupled adsorption-reduction\" mechanism. Higher Cr(VI) removal capacity is demonstrated for ACs having higher surface area (qm is 140.9 mg/g according Langmuir modelling). Cr(VI) removal is found to be pH dependent with a maximum at pH 1. However at that pH significant amounts of Cr remain in the solution as Cr(III). At pH 2 lower amount of Cr(VI) is removed compensated by a higher removal of Cr(III) resulting in a higher amount of adsorbed Crtot. Therefore adsorption at pH 2 is found to be appropriate. The removal capacity of the studied ACs towards Cr(VI) is almost independent of activation time.
Key Words
    manure; activated carbon; chromium; adsorption
Lenia Gonsalvesh: Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
Grazyna Gryglewicz: Department of Polymer and Carbonaceous Materials, Faculty of Chemistry, Wroclaw University of Technology, 50-344 Wroclaw, Poland
Robert Carleer and Jan Yperman: Research group of Applied and Analytical Chemistry, Hasselt University, B-3590 Diepenbeek, Belgium

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