Document Detail

Reduction and immobilization of hexavalent chromium with coal- and humate-based sorbents.
MedLine Citation:
PMID:  19215962     Owner:  NLM     Status:  MEDLINE    
Two kinds of the commercially available sorbents containing humic acids as active constituents were used for Cr(VI) reduction and removal, namely oxihumolite (naturally occurring weathered young brown coal) and iron humate (IH) (waste material produced during industrial manufacturing of humic substances). The mechanisms of the chromium removal involve the reduction of Cr(VI) (by humic substances or by Fe(II) ions) and subsequent binding of Cr(III) to a humic acid matrix. Other metal-binding mechanisms possibly effective in the process of Cr(VI) removal, e.g., coprecipitation or surface precipitation of Fe(III)/Cr(III) hydroxides, are also discussed. Oxihumolite was able to remove Cr(VI) from strongly acidic solutions with pH below ca. 2. IH, on the other hand, exhibited a maximum sorption capability in slightly acidic solutions with pH above ca. 3. Over the whole examined range (pH 1-5), however, IH was able to reduce Cr(VI) almost completely to its less toxic trivalent state. A sufficiently high sorption capacity (20 mg g(-1)) was found for chromium removal with IH in an unbuffered system, where the "natural" pH values governed by the buffering capacity of the sorbent itself ranged from 3.9 to 4.6. It follows from extraction studies with the loaded (spent) sorbents that chromium is bound strongly to the sorbent, and thus risks of its subsequent liberation into the environment are minimized. Similarity in the extraction behavior of the Cr(III)-loaded and Cr(VI)-loaded sorbents supported the above-mentioned mechanisms of the Cr(VI) removal.
Pavel Janos; Václav Hůla; Petra Bradnová; Vera Pilarová; Josef Sedlbauer
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-02-11
Journal Detail:
Title:  Chemosphere     Volume:  75     ISSN:  1879-1298     ISO Abbreviation:  Chemosphere     Publication Date:  2009 May 
Date Detail:
Created Date:  2009-04-13     Completed Date:  2009-06-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0320657     Medline TA:  Chemosphere     Country:  England    
Other Details:
Languages:  eng     Pagination:  732-8     Citation Subset:  IM    
Faculty of the Environment, University of Jan Evangelista Purkyne, Králova Výsina 7, 40096 Ustí nad Labem, Czech Republic.
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MeSH Terms
Chromium / chemistry*
Humic Substances
Hydrogen-Ion Concentration
Reg. No./Substance:
0/Coal; 0/Humic Substances; 18540-29-9/chromium hexavalent ion; 7440-47-3/Chromium

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