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Sorption influenced transport of ionizable pharmaceuticals onto a natural sandy aquifer sediment at different pH 总被引:3,自引:0,他引:3
The pH-dependent transport of eight selected ionizable pharmaceuticals was investigated by using saturated column experiments. Seventy-eight different breakthrough curves on a natural sandy aquifer material were produced and compared for three different pH levels at otherwise constant conditions. The experimentally obtained KOC data were compared with calculated KOC values derived from two different log KOW-log KOC correlation approaches. A significant pH-dependence on sorption was observed for all compounds with pKa in the considered pH range. Strong retardation was measured for several compounds despite their hydrophilic character. Besides an overall underestimation of KOC, the comparison between calculated and measured values only yields meaningful results for the acidic and neutral compounds. Basic compounds retarded much stronger than expected, particularly at low pH when their cationic species dominated. This is caused by additional ionic interactions, such as cation exchange processes, which are insufficiently considered in the applied KOC correlations. 相似文献
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Occurrence of coal and coal-derived particle-bound polycyclic aromatic hydrocarbons (PAHs) in a river floodplain soil 总被引:4,自引:0,他引:4
Yang Y Ligouis B Pies C Grathwohl P Hofmann T 《Environmental pollution (Barking, Essex : 1987)》2008,151(1):121-129
A PAH contaminated river floodplain soil was separated according to grain size and density. Coal and coal-derived particles from coal mining, coal industry and coal transportation activities were identified by organic petrographic analysis in our samples. Distinct concentrations of PAHs were found in different grain size and density fractions, however, similar distribution patterns of PAHs indicated similar sources. In addition, although light fractions had the mass fraction by weight of less than 5%, they contributed almost 75% of the total PAHs in the soil. PAH concentrations of all sub fractions showed positive correlation with their TOC contents. Altogether, coal and coal-derived particles that were abundant in light fractions could be the dominant geosorbents for PAHs in our samples. 相似文献
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Differences in surface characteristics between alkaline and acidic shales are demonstrated in the present study. The alkaline
shales are characterized by convex surface titration profiles, while the acidic shale exhibits a concave titration profile.
Analysis of surface functional groups reveal that carboxylic acids predominate in alkaline shales and the acidic shale is
characterized by C=S, C=N (pyridine derivative) and urea (C=O) functional groups, while it lacks –COOH group. The close proximity
between pH and point of zero charge for the most acidic and alkaline shales indicate that surface complexation may not play
a dominant role in sorption when the system pH is controlled by these sediments. 相似文献
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