Competitive adsorption of aqueous carbonic and acetic acids by an aluminum oxide

Journal Article · · Soil Science Society of America Journal; (United States)

DOI:https://doi.org/10.2136/sssaj1990.03615995005400030009x· OSTI ID:5598452

Schulthess, C P ^[1]; McCarthy, J F ^[2]

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1. National Chemical Lab. for Industry, Ibaraki (Japan)
2. Oak Ridge National Lab., TN (USA)

The prominence of carbonates in nature and their potential competitiveness with organic acids for sorption sites in soils may be underestimated by researchers who study the mobility of natural organic matter. The pH-dependent adsorption envelopes of Na salts of acetic acid (AcOH) and carbonates (H{sub 2}CO{sub 3}, HCO{sup {minus}}{sub 3}, CO{sub 3}{sup 2{minus}}) on an Al oxide were studied to elucidate the effect of carbonates on the adsorption behavior of organic acids. Using 10{sup {minus}3.48} and 10{sup {minus}3} M concentrations of the carbonate salt reduced the amount of acetate adsorbed by 29 and 48%, respectively. Using 10{sup {minus}3.48} M concentrations of acetate, however, did not affect the carbonate adsorption at equimolar concentrations. The relative affinity of the aqueous compounds for adsorption by the Al oxide was determined based on the pH value of their adsorption edges (i.e., based on their adsorption competitiveness relative to the aqueous OH anions). The relative affinity for adsorption by the Al oxide was OH > carbonate > acetate > Cl. The amount of both the acetate and carbonate adsorbed by Al oxide are reduced in the presence of competitive OH anions at high pH and high concentrations of Cl anions at low pH. The adsorption mechanisms of the carbonate and acetate compounds are suspected to be similar based on the chemical structure of these compounds. Batch adsorption studies, however, cannot unequivocally identify a bonding mechanism, which may include ligand exchange or H bonding. The authors additionally stress that both the affinities and concentrations of the aqueous compounds play an important role in competitive adsorption behavior.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5598452
• Journal Information: Soil Science Society of America Journal; (United States), Journal Name: Soil Science Society of America Journal; (United States) Vol. 54:3; ISSN SSSJD; ISSN 0361-5995
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
ACETIC ACID
ADSORPTION
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AQUEOUS SOLUTIONS
CARBON COMPOUNDS
CARBONIC ACID
CARBOXYLIC ACIDS
CHALCOGENIDES
DISPERSIONS
ENVIRONMENTAL TRANSPORT
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MASS TRANSFER
MIXTURES
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
SOLUTIONS
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES