Linked Life Data

17508766

Source:http://linkedlifedata.com/resource/pubmed/id/17508766

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
13
pubmed:dateCreated
2007-6-12
pubmed:abstractText
The adsorption of dicarboxylic acids by kaolinite and montmorillonite at different pH conditions was investigated using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) and ex situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The sorption capacity of montmorillonite was greater than that of kaolinite. Adsorption of dicarboxylic acids (succinic acid, glutaric acid, adipic acid, and azelaic acid) was the highest at pH 4 as compared with those at pH 7 and 9. These results indicate that sorption is highly pH-dependent and related to the surface characteristics of minerals. The aliphatic chain length of the dicarboxylic acids highly influenced the sorption amount at acidic pH, regardless of the clay mineral species: succinic acid [HOOC(CH2)2COOH] < glutaric acid [HOOC(CH2)3COOH] < adipic acid [HOOC(CH2)4COOH] < azelaic acid [HOOC(CH2)7COOH]. With in situ ATR-FTIR analysis, most samples tend to have outer-sphere adsorption with the mineral surfaces at all tested pHs. However, inner-sphere coordination between the carboxyl groups and mineral surfaces at pH 4 was dominant from DRIFT analysis with freeze-dried complex samples. The complexation types, inner- or outer-sphere, depended on dicarboxylic acid species, pH, mineral surfaces, and solvent conditions. From the experimental data, we suggest that organic acids in an aqueous environment prefer to adsorb onto the test minerals by outer-sphere complexation, but inner-sphere complexation is favored under dry conditions. Thus, organic acid binding onto clay minerals under dry conditions is stronger than that under wet conditions, and we expect different conformations and aggregations of sorbed organic acids as influenced by complexation types. In the environment, natural organic material (NOM) may adsorb predominantly on positively charged mineral surfaces at the aqueous interface, which can convert into inner-sphere coordination during dehydration. The stable NOM/mineral complexes formed by frequent wetting-drying cycles in nature may resist chemical/microbial degradation of the NOM, which will affect carbon storage in the environment and influence the sorption of organic contaminants.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0743-7463
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7024-31
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Adsorption of dicarboxylic acids by clay minerals as examined by in situ ATR-FTIR and ex situ DRIFT.
pubmed:affiliation
Department of Plant, Soil, and Insect Sciences, University of Massachusetts, Amherst, MA 01003, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.