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Sorption Coefficient (sorption + coefficient)
Selected AbstractsThe effect of pH and ionic strength on the sorption of sulfachloropyridazine, tylosin, and oxytetracycline to soilENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2006Thomas L. ter Laak Abstract Antimicrobial agents are the most heavily used pharmaceuticals in intensive husbandry. Their usual discharge pathway is application to agricultural land as constituents of animal manure, which is used as fertilizer. Many of these compounds undergo pH-dependent speciation and, therefore, might occur as charged species in the soil environment. Hence, pH and ionic strength of the soil suspension can affect the sorption behavior of these compounds to soil. Consequently, the soil sorption of three antimicrobial agents,sulfachloropyridazine (SCP), tylosin (TYL), and oxytetracycline (OTC),was investigated. Their respective sorption coefficients in two agricultural soils ranged from 1.5 to 1,800 L/kg. Sorption coefficients were greater under acidic conditions. Addition of an electrolyte to the solution led to decreased sorption of TYL and OTC by a factor of 3 to 20, but it did not influence the sorption of SCP. This behavior was analyzed by accounting for the pH-dependent speciation of TYL and OTC and considering the presence of OTC-calcium complexes. It appears that the decreased sorption of TYL and OTC with increasing ionic strength results from competition of the electrolyte cations with the positively charged TYL species and the positively charged OTC complexes. A model linking sorbate speciation with species-specific sorption coefficients can describe the pH dependence of the apparent sorption coefficients. This modeling approach is proposed for implementation in the assessment of sorption of ionizable compounds. [source] Validation of a modified Flory-Huggins concept for description of hydrophobic organic compound sorption on dissolved humic substancesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Anett Georgi Abstract Sorption coefficients(KDOC) on dissolved organic matter (DOM) have been determined by means of solid-phase microextraction (SPME) for hydrophobic organic compounds (HOCs) of various classes, for example, polycyclic aromatic hydrocarbons (PAHs), noncondensed arenes, and alkanes. Relating the KDOC values obtained to the octanol-water partition coefficients of the solutes results in class-specific correlations. Obviously, PAHs have a higher affinity to DOM than other HOCs with equal KOW values. The different KDOC to KOW correlations can be combined into one general formula based on a modified Flory-Huggins concept. It permits the calculation of sorption coefficients from the solubility parameters (,) and KOW values of the solutes and the solubility parameter of the sorbent. The latter value, which is specific to the DOM under consideration, can be determined from a single measured sorption coefficient. By applying the proposed Flory-Huggins concept, which is based on the presumption of nonspecific interactions between HOCs and DOM, the different affinities of PAHs, noncondensed arenes, and alkanes to DOM can be accurately predicted. [source] Sorption of humic acids and ,-endosulfan by clay mineralsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2006Sarunya Hengpraprom Abstract Sorption of ,-endosulfan by kaolinite and montmorillonite alone and in the presence of sorbed and dissolved humic acid (HA) was investigated (pH 8 and 25°C). Three types of HA, Elliot soil HA (EHA), Peat HA (PHA), and Summit Hill HA (SHHA), were used to represent typical humic substances found in soils. For sorption of HA by either mineral, Freundlich sorption coefficient (Kf) values appeared to decrease in the order of EHA > PHA > SHHA, which followed increasing polarity (expressed as the O/C atomic ratio) and decreasing percent-carbon content. For both clays, sorption of ,-endosulfan by the HA mineral complex was greater than for sorption by the clay alone. Sorption of ,-endosulfan by the HA mineral complexes followed the same order as the Kf of the HAs (EHA > PHA > SHHA). Based on the amount of HA adsorbed by each mineral, organic carbon partition coefficients (KOC) were determined for sorption of ,-endosulfan by two of the HA mineral complexes. The value of KOC for ,-endosulfan sorption was greater for kaolinite EHA than kaolinite SHHA. However, the opposite trend was found with the montmorillonite HA complexes. Montmorillonite appeared to sorb ,-endosulfan and/or HA with higher affinity than kaolinite, which likely is due to its 2:1 layer structure and higher surface area. Sorption of endosulfan diol, a hydrolysis product, by the minerals was much less than the parent pesticide. [source] Validation of a modified Flory-Huggins concept for description of hydrophobic organic compound sorption on dissolved humic substancesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Anett Georgi Abstract Sorption coefficients(KDOC) on dissolved organic matter (DOM) have been determined by means of solid-phase microextraction (SPME) for hydrophobic organic compounds (HOCs) of various classes, for example, polycyclic aromatic hydrocarbons (PAHs), noncondensed arenes, and alkanes. Relating the KDOC values obtained to the octanol-water partition coefficients of the solutes results in class-specific correlations. Obviously, PAHs have a higher affinity to DOM than other HOCs with equal KOW values. The different KDOC to KOW correlations can be combined into one general formula based on a modified Flory-Huggins concept. It permits the calculation of sorption coefficients from the solubility parameters (,) and KOW values of the solutes and the solubility parameter of the sorbent. The latter value, which is specific to the DOM under consideration, can be determined from a single measured sorption coefficient. By applying the proposed Flory-Huggins concept, which is based on the presumption of nonspecific interactions between HOCs and DOM, the different affinities of PAHs, noncondensed arenes, and alkanes to DOM can be accurately predicted. [source] Quantification of irreversible benzene sorption in sandy materialsHYDROLOGICAL PROCESSES, Issue 17 2004Dong-Ju Kim Abstract Based on a previous study of the irreversible sorption of benzene in sandy aquifer materials, we further investigated a method to quantify an irreversible sorption coefficient of aqueous benzene. Assuming that the rate of irreversible loss from the solution to the sorption sites followed first-order kinetics, the irreversible sorption coefficient was derived from a kinetic batch sorption test conducted for an appropriate soil-to-solution ratio to reflect the flow conditions imposed on a column test. Simulation results revealed that the irreversible sorption coefficient estimated from the kinetic batch test provided a good agreement with the measured data obtained from the column test, indicating that the method proposed in this study can be used to quantify the irreversible sorption coefficient. Copyright © 2004 John Wiley & Sons, Ltd. [source] Sorption of HOC in soils with carbonaceous contamination: Influence of organic-matter compositionJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2005Kerstin Abelmann Abstract Detailed information about structure and composition of organic sorbents is required to understand their impact on sorption capacity and sorption kinetic of organic pollutants. Therefore, the chemical composition of organic material from 18 geosorbents was investigated by solid-state 13C nuclear-magnetic-resonance (NMR) spectroscopy. Structural parameters such as aromaticity, polarity, and alkyl-C content were related to the Freundlich sorption exponent (1/n) and the sorption coefficient . The geosorbents included three natural and four combusted coals (carbonaceous material), three Histosols, five mineral soils from Germany containing inputs of technogenic carbonaceous material, derived from industrial activities, and four non-contaminated mineral soils from Germany. Equilibrium sorption was measured for five hydrophobic organic compounds and analyzed with the solubility-normalized Freundlich sorption isotherm. With increasing maturation degree, the proportion of polar constituents decreases from the natural soils to the coals. In contrast to the non-polluted mineral soils, the soils with technogenic input are characterized by high aromaticity and low polarity. A positive correlation between sorption coefficient and aromaticity was found. The Freundlich exponent (1/n) is negatively correlated with the aromaticity, denoting an increase of adsorption processes with increasing aromaticity. Likewise, the contribution of partitioning decreases. This sorption mechanism predominates only if the organic matter in the samples contains a high proportion of polar compounds. Sorption von HOC in Böden mit kohleartiger Kontamination: Einfluss der Zusammensetzung des organischen Materials Um den Einfluss von organischen Sorbenten auf die Sorptionskapazität und die Kinetik organischer Schadstoffe zu verstehen, müssen detaillierte Informationen über deren Struktur und Zusammensetzung vorliegen. Aus diesem Grund wurde das organische Material von 18 Geosorbenten mittels der Festkörper- 13C-NMR-Spektroskopie untersucht. Strukturelle Parameter wie zum Beispiel die Aromatizität, die Polarität und der Alkyl-C-Gehalt wurden mit dem Freundlich-Exponenten 1/n und dem Sorptionskoeffizienten korreliert. Die Geosorbenten bestehen aus drei natürlichen und vier thermisch behandelten Kohlen, drei Histosolen und fünf deutschen Mineralböden, die technogenes kohlehaltiges Material aus industriellen Aktivitäten enthalten, sowie vier nicht kontaminierten deutschen Böden. Die Gleichgewichtssorption wurde für fünf hydrophobe, organische Verbindungen gemessen und mit Hilfe der löslichkeitsnormalisierten Freundlich-Isotherme analysiert. Der Anteil der polaren Komponenten nimmt von den natürlichen Böden zu den Kohlen mit zunehmendem Inkohlungsstadium ab. Im Gegensatz zu den nicht kontaminierten Mineralböden weisen die Böden mit technogenen Bestandteilen eine hohe Aromatizität und eine geringe Polarität auf. Zwischen dem und der Aromatizität ergab sich ein positiver Zusammenhang. Der Freundlich Exponent (1/n) korreliert negativ mit der Aromatizität. Dies weist auf eine Zunahme der Adsorptionsprozesse mit Erhöhung der Aromatizität hin. Der Beitrag der Partitionierung sinkt ebenfalls. Dieser Sorptionsmechanismus dominiert nur in den Proben, in denen das organische Material einen hohen Anteil polarer Bestandteile besitzt. [source] Review of Pesticide Retention Processes Occurring in Buffer Strips Receiving Agricultural Runoff,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2010Kapil Arora Arora, Kapil, Steven K. Mickelson, Matthew J. Helmers, and James L. Baker, 2010. Review of Pesticide Retention Processes Occurring in Buffer Strips Receiving Agricultural Runoff. Journal of the American Water Resources Association (JAWRA) 46(3):618-647. DOI: 10.1111/j.1752-1688.2010.00438.x Abstract:, Review of the published results shows that the retention of the two pesticide carrier phases (runoff volume and sediment mass) influences pesticide mass transport through buffer strips. Data averaged across different studies showed that the buffer strips retained 45% of runoff volume (ranging between 0 and 100%) and 76% of sediment mass (ranging between 2 and 100%). Sorption (soil sorption coefficient, Koc) is one key pesticide property affecting its transport with the two carrier phases through buffer strips. Data from different studies for pesticide mass retention for weakly (Koc < 100), moderately (100 < Koc < 1,000), and strongly sorbed pesticides (Koc > 1,000) averaged (with ranges) 61 (0-100), 63 (0-100), and 76 (53-100) %, respectively. Because there are more data for runoff volume and sediment mass retention, the average retentions of both carrier phases were used to calculate that the buffer strips would retain 45% of weakly to moderately sorbed and 70% of strongly sorbed pesticides on an average basis. As pesticide mass retention presented is only an average across several studies with different experimental setups, the application of these results to actual field conditions should be carefully examined. [source] Sorption of polycyclic aromatic hydrocarbons into liposomes (artificial cell membranes) and the effects of dissolved natural organic matterLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 4 2002Yoshihisa Shimizu Abstract Dissolved natural organic matter (NOM) occurs widely in the aquatic environment and affects the fate of microorganic pollutants (e.g. intake, accumulation, movement, degradation, toxicity). The effect of NOM on the intake into biota (living cells) is very important. In the present study, the effects of coexisting NOM on the intake of microorganic pollutants into aquatic biota were experimentally evaluated. The NOM was concentrated from Lake Biwa water using a reverse osmosis filtration membrane. Two polycyclic aromatic hydrocarbons (PAH; pyrene and phenanthrene) were used as representative microorganic pollutants. Liposomes were synthesized in the laboratory to simulate living cell membranes and were used to investigate the intake of microorganic pollutants into aquatic biota. The experimental results (PAH onto NOM, NOM into liposomes, and PAH into liposomes) indicated that the sorption of PAH into liposomes was suppressed, apparently by PAH binding with NOM in the aqueous phase. This suggests that the accumulation and/or toxicity of microorganic pollutants can be retarded by NOM in the aqueous environment. Moreover, the experimental results indicated that sorption into liposomes (the liposome/water sorption coefficient, Klipw) could be a better parameter for estimating the intake of microorganic pollutants into aquatic biota than the n-octanol/water partition coefficient (Kow) in the aqueous environment. [source] The effect of pH and ionic strength on the sorption of sulfachloropyridazine, tylosin, and oxytetracycline to soilENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2006Thomas L. ter Laak Abstract Antimicrobial agents are the most heavily used pharmaceuticals in intensive husbandry. Their usual discharge pathway is application to agricultural land as constituents of animal manure, which is used as fertilizer. Many of these compounds undergo pH-dependent speciation and, therefore, might occur as charged species in the soil environment. Hence, pH and ionic strength of the soil suspension can affect the sorption behavior of these compounds to soil. Consequently, the soil sorption of three antimicrobial agents,sulfachloropyridazine (SCP), tylosin (TYL), and oxytetracycline (OTC),was investigated. Their respective sorption coefficients in two agricultural soils ranged from 1.5 to 1,800 L/kg. Sorption coefficients were greater under acidic conditions. Addition of an electrolyte to the solution led to decreased sorption of TYL and OTC by a factor of 3 to 20, but it did not influence the sorption of SCP. This behavior was analyzed by accounting for the pH-dependent speciation of TYL and OTC and considering the presence of OTC-calcium complexes. It appears that the decreased sorption of TYL and OTC with increasing ionic strength results from competition of the electrolyte cations with the positively charged TYL species and the positively charged OTC complexes. A model linking sorbate speciation with species-specific sorption coefficients can describe the pH dependence of the apparent sorption coefficients. This modeling approach is proposed for implementation in the assessment of sorption of ionizable compounds. [source] Validation of a modified Flory-Huggins concept for description of hydrophobic organic compound sorption on dissolved humic substancesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Anett Georgi Abstract Sorption coefficients(KDOC) on dissolved organic matter (DOM) have been determined by means of solid-phase microextraction (SPME) for hydrophobic organic compounds (HOCs) of various classes, for example, polycyclic aromatic hydrocarbons (PAHs), noncondensed arenes, and alkanes. Relating the KDOC values obtained to the octanol-water partition coefficients of the solutes results in class-specific correlations. Obviously, PAHs have a higher affinity to DOM than other HOCs with equal KOW values. The different KDOC to KOW correlations can be combined into one general formula based on a modified Flory-Huggins concept. It permits the calculation of sorption coefficients from the solubility parameters (,) and KOW values of the solutes and the solubility parameter of the sorbent. The latter value, which is specific to the DOM under consideration, can be determined from a single measured sorption coefficient. By applying the proposed Flory-Huggins concept, which is based on the presumption of nonspecific interactions between HOCs and DOM, the different affinities of PAHs, noncondensed arenes, and alkanes to DOM can be accurately predicted. [source] The role of mineral and organic components in phenanthrene and dibenzofuran sorption by soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2006R. Celis Summary Improved predictions of sorption of hydrophobic organic compounds (HOCs) in soil require a better knowledge of the relative contribution of inorganic and organic soil constituents to the sorption process. In this paper, sorption of a three-ring polycyclic aromatic hydrocarbon (phenanthrene) and a three-ring heterocyclic,aromatic compound (dibenzofuran) by six agricultural soils, their clay-size fractions, and a series of single, binary, and ternary model sorbents was evaluated to elucidate the relative role of soil mineral and organic components in the retention of these two model HOCs. The sorption coefficients for phenanthrene and dibenzofuran on purified soil organic materials (Kd = 821,9080 litre kg,1) were two orders of magnitude greater than those measured on mineral model sorbents (Kd = 0,114 litre kg,1). This, along with the strong correlation between sorption and the organic C content of the soil clay fractions (r = 0.99, P < 0.01), indicated a primary role of soil organic matter in the retention of both compounds. However, weak relationships between phenanthrene and dibenzofuran sorption coefficients and the organic C content of the bulk soils and variability of Koc values among soils, clay fractions, and model sorbents (1340,21020 litre kg,1 C for phenanthrene and 1685,7620 litre kg,1 C for dibenzofuran) showed that sorption was not predictable exclusively from the organic C content of the materials. Organic matter heterogeneity and domain blockage arising from organic matter,clay interactions and associated pH shifts were identified as the most likely causes of the different organic C-normalized sorption capacities of the soils. A direct contribution from minerals to the sorption of phenanthrene and dibenzofuran by the soils studied was likely to be small. Our results suggested that suitable descriptors for the extent of organic matter,mineral interactions would help to improve current Koc -based sorption predictions and subsequently the assessment of risk associated with the presence of HOCs in soil. [source] Molecular transport of aromatic hydrocarbons through lignin-filled natural rubber compositesPOLYMER COMPOSITES, Issue 1 2007Thomas V. Mathew The diffusion and transport of organic solvents through lignin-filled natural rubber composites have been studied in the temperature range 25,45°C. The diffusion of aromatic solvents through these samples were studied with special reference to the effect of filler concentration, penetrant size, and temperature. Transport coefficients such as diffusion, permeation, and sorption coefficients were estimated. The van't Hoff relationship was used to determine the thermodynamic parameters. The first order kinetic rate constant has been evaluated. A correlation between theoretical and experimental sorption results was evaluated. POLYM. COMPOS., 28:15,22, 2007. © 2007 Society of Plastics Engineers [source] | |||||||||||||