Low-Molecular-Weight Organic Acids Influence the Sorption of Phenanthrene by Different Soil Particle Size Fractions

Abstract

The impact of low-molecular-weight organic acids (LMWOAs) on the sorption of phenanthrene (a representative polycyclic aromatic hydrocarbon) by different particle size fractions of a soil was investigated using a batch technique. Citric and malic acids were used in experiments. Four soil fractions were fractionated: fine sand, silt, coarse clay, and fine clay. Laser granulometry confirmed the suitability of the fractionation method used for the particle size distributions in this investigation. The sorption of phenanthrene by the different soil fractions was described well using a linear distribution-type model, and the distribution coefficients () followed a descending order of fine sand > fine clay > coarse clay > silt, irrespective of the addition of organic acids. This order was significantly positively correlated with the organic carbon content of test soil solids. The values for phenanthrene sorption by soil fractions initially increased but then decreased as the concentrations of citric and malic acids increased (0-1000 mmol L). The presence of citric and malic acid at lower concentrations (<100 mmol L) generally promoted the sorption of phenanthrene, while higher concentrations (>100 mmol L) inhibited sorption irrespective of the soil fraction. The mechanism of the LMWOA-influenced sorption of phenanthrene by test solids is discussed based on the observed sorption of organic acid, the dissolution of metal cations and minerals in soil, and the competition from dissolved organic matter in solution that were released from soil solids.

Mechanism and Implication of the Sorption of Perfluorooctanoic Acid by Varying Soil Size Fractions

“…The size ranges of the soil fractions were determined using a laser diffraction granulometer with a measuring range of 0.02–2 000 μm (Mastersizer S 2000; Malvern Instruments, Ltd., Malvern, U.K.). The size determination was conducted using aqueous soil suspensions, with the size calculated according to the percentage volume distribution based on the Fraunhofer approximation . The Brunauer–Emmett–Teller (BET) specific surface area, pore volume, and pore size of soil particle-size fractions were measured by a BET surface area analyzer (TriStar II 3020; MicroMetrics, Norcross, GA, USA) using a nitrogen sorption/desorption technique at 77 K. Other basic properties, including OM content, CEC, and pH were determined according to the method described above…”

Relationship Between Physical and Chemical Properties of Entisols-Fluvents and Erosion in the São Francisco River

“…This high clay dispersion must have been due to an excess of electronegative charges in the soil arising from organic matter constituents ( VAN DEN BOGAERT;LABILLE;CORNU, 2015). In a study by Gao et al (2015), organic acids of low molecular weight increased the amount of dispersed clay. In agreement with these studies, Table 3 shows the high contents of organic matter in the soil (SOM) in the layers Ap and AC, which may explain the high WDC and DI values compared to those in subsurface layers (Table 6).…”

Sorption Mechanism, Kinetics, and Isotherms of Di-n-butyl Phthalate to Different Soil Particle-Size Fractions

“…Soils are composed of various size fractions. , Sorption of organic pollutants to soil particle-size fractions differs greatly due to variations in physicochemical properties, especially in the contents and functions of OM. ,, For example, the sorption capacity (log K d ) of hexachlorobenzene and phenoxyalkanoic herbicides increased with decreasing soil particle size, but this pattern was not observed for phenanthrene sorption to different soil size fractions . Gao et al demonstrated that the carbon-normalized distribution constant ( K oc ) of phenanthrene in silt was 1–5 times higher than in other fractions despite the lowest distribution coefficient ( K d ) being observed in this fraction . Therefore, compared with conventional sorption experiments using the whole soil sample, a sorption experiment using different soil particle-size fractions may provide new insights into the sorption behaviors of organic pollutants, e.g., which soil fraction contributes more to the total sorption in the original soil and what mechanism governs the sorption of various soil size fractions .…”

“…Therefore, compared with conventional sorption experiments using the whole soil sample, a sorption experiment using different soil particle-size fractions may provide new insights into the sorption behaviors of organic pollutants, e.g., which soil fraction contributes more to the total sorption in the original soil and what mechanism governs the sorption of various soil size fractions . At present, there are many publications reporting sorption of organic pollutants such as polycyclic aromatic hydrocarbons, , pesticides, pharmaceuticals, and personal care products, , to soil particle-size fractions. However, little information about PAEs is available.…”

“…25 Gao et al demonstrated that the carbon-normalized distribution constant (K oc ) of phenanthrene in silt was 1−5 times higher than in other fractions despite the lowest distribution coefficient (K d ) being observed in this fraction. 29 Therefore, compared with conventional sorption experiments using the whole soil sample, a sorption experiment using different soil particle-size fractions may provide new insights into the sorption behaviors of organic pollutants, e.g., which soil fraction contributes more to the total sorption in the original soil and what mechanism governs the sorption of various soil size fractions. 30 At present, there are many publications reporting sorption of organic pollutants such as polycyclic aromatic hydrocarbons, 25,29 pesticides, 28 personal care products, 30,31 to soil particle-size fractions.…”