Copper behaviour in a Podosol. 1. pH-dependent sorption - desorption, sorption isotherm analysis, and aqueous speciation modelling

Soil Research ◽  
2005 ◽  
Vol 43 (4) ◽  
pp. 491 ◽  
Author(s):  
Edward D. Burton ◽  
Ian R. Phillips ◽  
Darryl W. Hawker ◽  
Dane T. Lamb
Keyword(s):  
Solid Solution ◽  
Sorption Isotherm ◽  
Sorption Isotherms ◽  
Distribution Coefficients ◽  
Linear Distribution ◽  
Subsequent Formation ◽  
Kd Values ◽  
Effects Of Ph ◽  
Speciation Modelling ◽  
Ph Dependent

The effects of pH and Cu loading on the solid/solution partitioning of Cu in a Podosol from south-east Queensland, Australia was examined. Sorption–desorption of Cu exhibited maximum linear distribution coefficients (KD) at approximately pH 5. Observed decrease in KD values at pH >5 was attributed to increased solubility of native dissolved organic carbon (DOC) at higher pH and subsequent formation of non-sorbing Cu–DOC complexes. Speciation modelling with the MINTEQA2 code indicated that >90% of aqueous Cu was present as Cu–DOC complexes at pH >5.5. The effect of Cu loading was examined with sorption isotherm analysis at pH 5 using solid : solution ratio approaches that were both constant (1 : 2 and 1 : 10) and variable. As the solid : solution ratio increased, the proportion of Cu sorbed decreased due to the formation of Cu-DOC complexes. However, this effect was negligible once these Cu–DOC complexes were accounted for via free Cu2+ sorption isotherms. This indicated that Cu2+ sorption at concentrations <0.08 mg/L was described by a KD value of approximately 3000 L/kg. Despite this relatively high KD value for Cu2+ sorption, the results indicate that Cu–DOC complexes significantly enhance Cu solubility in soils high in DOC.

Dissolution of willemite polycrystals: effects of pH, temperature and TiO2 solid solution

1993 ◽  
Vol 28 (7) ◽  
pp. 1781-1787 ◽  
Author(s):  
H. Y. Chang ◽  
C. C. Lin ◽  
P. Shen ◽  
A. C. Su ◽  
C. C. Lee
Keyword(s):  
Solid Solution ◽  
Effects Of Ph

Land use effects on sorption of pesticides and their metabolites in sandy soils. I. Fenamiphos and two metabolites, fenamiphos sulfoxide and fenamiphos sulfone, and fenarimol and azinphos methyl

Soil Research ◽  
2003 ◽  
Vol 41 (5) ◽  
pp. 847 ◽  
Author(s):  
D. P. Oliver ◽  
R. S. Kookana ◽  
R. B. Salama
Keyword(s):  
Land Use ◽  
Sorption Isotherms ◽  
Strong Relationship ◽  
Native Vegetation ◽  
Limited Information ◽  
Sorption Behaviour ◽  
Complex Interactions ◽  
Azinphos Methyl ◽  
Kd Values ◽  
Land Use Effects

There is very limited information about the effect of land use on sorption behaviour of organic chemicals. It has been documented that clearing natural vegetation and cropping soil typically decreases the original organic carbon (OC) content of soil. Because OC is one of the major parameters controlling pesticide sorption, the effects of land use on the sorption behaviour of fenamiphos and its 2 main metabolites, fenamiphos sulfone (f. sulfone) and fenamiphos sulfoxide (f. sulfoxide), together with fenarimol and azinphos methyl were investigated. Based on sorption isotherms for a subset of soils, using a range of concentrations (2.5, 5.0, 7.5, and 10 mg/L), the use of a single concentration (2 mg/L) was considered adequate to determine sorption coefficients. Generally the Kd values for fenamiphos were significantly (P�<�0.005) higher than those of its 2 metabolites. The sorption coefficients decreased in the order: fenamiphos >> f. sulfone ≥� f. sulfoxide. As both metabolites can apparently move more easily through soil than fenamiphos, they would pose a greater risk to groundwater contamination. For all compounds, only weak relationships were determined between Kd and pH or %silt + clay. Similarly, the relationship between Kd and %OC was poor, when data from all soils were combined for analysis. However, a strong relationship was obtained between sorption coefficients and %OC for fenamiphos in market garden soils (r2 = 0.76***). This was also the case for azinphos methyl and fenarimol, particularly in soils under native vegetation (r2�=�0.71 and 0.73***, respectively). At a given OC content, the soils under Banksia bush generally showed greater sorption than those under market gardens. This effect became more pronounced with increasing OC content, suggesting that the nature and composition of the OC in soils under native vegetation are likely to be different from that in cultivated soils. Clearly the OC content is not an adequate parameter describing the complex interactions between pesticides and organic matter.

Effects of pH on the Transformation of Gypsum to Carbonate Apatite in the Presence of Ammonium Hydrogen Phosphate

2006 ◽  
Vol 309-311 ◽  
pp. 199-202 ◽  
Author(s):  
Ishikawa Kunio ◽  
Yumiko Suzuki ◽  
Shigeki Matsuya ◽  
Masaharu Nakagawa ◽  
Kiyoshi Koyano
Keyword(s):  
The Other ◽  
Dicalcium Phosphate ◽  
Carbonate Apatite ◽  
Compositional Change ◽  
Hydrogen Phosphate ◽  
Detailed Mechanism ◽  
Effects Of Ph ◽  
Ammonium Hydrogen ◽  
Ammonium Hydrogen Phosphate ◽  
Ph Dependent

Effects of pH on the transformation of gypsum to apatite in the presence of ammonium hydrogen phosphate was studied using NH4H2PO4, (NH4)2HPO4 and (NH4)3PO4. When set gypsum was immersed to ammonium hydrogen phosphate, pH of the solution decreased regardless of the solution. Although pH of the solution decreased, no significant compositional change was observed when gypsum was immersed in NH4H2PO4. On the other hand, apatite and small amount of dicalcium phosphate anhydrous (CaHPO4) was formed when gypsum was immersed in (NH4)2HPO4 solution. Only apatite was formed when gypsum was immersed in (NH4)3PO4 solution. Although the detailed mechanism for the pH dependent products has not been clarified, one of the causes may be the different thermodynamical difference between gypsum and apatite. We would like to recommend the use of (NH4)3PO4 solution since this provides higher pH and thus larger thermodynamical difference between apatite and gypsum and resulting pure apatite block.

Effective distribution coefficients of an ideal solid solution crystal: Monte Carlo simulation

2005 ◽  
Vol 276 (3-4) ◽  
pp. 635-642 ◽  
Author(s):  
Kiiko Matsumoto ◽  
Toshiharu Irisawa ◽  
Masao Kitamura ◽  
Etsuro Yokoyama ◽  
Yoshinao Kumagai ◽  
...  
Keyword(s):  
Solid Solution ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Distribution Coefficients ◽  
Solid Solution Crystal ◽  
Effective Distribution

Combining DLS, XRD, SEM-EDAX and EXAFS in the study of Zn(II) retention on a palygorskitic clay

Clay Minerals ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 205-212
Author(s):  
C. Aisa ◽  
R. A. Alvarez-Puebla ◽  
J. Blasco ◽  
J. C. Echeverría ◽  
J. J. Garrido
Keyword(s):  
Solid Solution ◽  
Chemical Species ◽  
Sorption Isotherms ◽  
Precipitation Process ◽  
Clay Material ◽  
Retention Capacity ◽  
X Ray ◽  
Surface Precipitation ◽  
Clay System ◽  
Complementary Techniques

AbstractClay materials play a key role in determining the retention capacity of a soil, and are widely used in waste treatments. One of the most commonly used clays is palygorskite. The aim of this research is to determine the chemical species formed by Zn when retained in a palygorskitic clay material. Adsorption isotherm analysis is useful in studying the retention process, because it provides a macroscopic view of the retention phenomena. Complementary techniques are needed in order to study the different retention processes. Sorption isotherms of Zn on palygorskitic clay were carried out; the supernatant was analysed by means of dynamic light scattering (DLS) and the residues by using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive angle X-ray (SEM-EDAX)analysis and extended X-ray absorption fine structure (EXAFS). Isotherm analysis shows that the global retention process could be due to the sum of two separate processes, adsorption and surface precipitation via solid-solution. This is supported by DLS, which shows that ζ potential increases as the Zn(II) is retained onto clay surfaces but remains constant during the precipitation process. The XRD pattern corresponding to the Zn-clay system showed weak new peaks, probably from zincite. The microanalysis by X-ray fluorescence of several spots selected for their different electronic densities indicated that the retained Zn was randomly distributed across the clay surface. Analysis by EXAFS supports the hypothesis of retention via adsorption and solid-solution surface precipitation.

Effects of pH, solid/solution ratio, ionic strength, and organic acids on Pb and Cd sorption on kaolinite

1991 ◽  
Vol 57-58 (1) ◽  
pp. 423-430 ◽  
Author(s):  
Robert W. Puls ◽  
Robert M. Powell ◽  
Donald Clark ◽  
Cynthia J. Eldred
Keyword(s):  
Solid Solution ◽  
Ionic Strength ◽  
Organic Acids ◽  
Effects Of Ph

scholarly journals The use of sorption and excess sorption isotherm in the mathematical modeling of the unsteady-state heat and humidity regime of the building envelope

2021 ◽  
Vol 2131 (5) ◽  
pp. 052072
Author(s):  
Z Zhou ◽  
K P Zubarev
Keyword(s):  
Water Vapor ◽  
Sorption Isotherm ◽  
Moisture Transfer ◽  
Sorption Isotherms ◽  
Building Envelope ◽  
Vapor Transfer ◽  
Potential Capacity ◽  
Partial Transfer ◽  
Relative Potential ◽  
Moisture Potential

Abstract In the given article the development of the moisture transfer equation based on the theory of moisture potential is considered. The task of combined heat and moisture transfer is one of the most complicated tasks in the building thermal physics field. The classical equations of moisture transfer by K.F. Fokin representing the transfer of moisture under the action of partial transfer potentials - the gradient of the partial pressure of water vapor and the gradient of humidity F - are listed. The possibility of uniform accounting of the combined water vapor transfer on the basis of the moisture potential F is described. The sorption isotherm for aerated concrete is constructed in accordance with the experiment carried out in a desiccator with an aqueous solution of sulfuric acid. A new equation of moisture transfer which takes into account moistening with vaporous moisture in the sorption zone of moisture and liquid moisture in the excess sorption zone of moisture is derived. In order to simplify the work with the obtained equation a new value of the relative potential capacity is introduced. A graph construction of sorption and excess sorption isotherms which are obtained using an analytical expression for the relative potential capacity is proposed. In the sorption zone of humidification the sorption and excess sorption isotherms coincide with the classical sorption isotherm. Meanwhile, in the excess sorption zone of humidification the sorption and excess sorption isotherms depend on temperature.

scholarly journals Magnetic Composite Sorbents for Trapping Heavy Metals from Liquid Waste and Their Immobilization in a Mineral-Like Matrix

2019 ◽  
pp. 445-457 ◽  
Author(s):  
Yana Yu. Chernykh ◽  
Tatiana A. Vereshchagina ◽  
Elena V. Mazurova ◽  
Vladimir A. Parfenov ◽  
Leonid A. Solovyev ◽  
...  
Keyword(s):  
Solid Phase ◽  
Liquid Waste ◽  
Sorption Isotherms ◽  
Distribution Coefficients ◽  
Magnetic Composite ◽  
Solid Phase Crystallization ◽  
Magnetic Composites ◽  
Magnetic Sorbents ◽  
Zircon Phase

Magnetic sorbents were prepared by addition of ferrospheres to zirconia-silica gel followed by thermal treatment at 500 °C. The ferrosphere narrow fraction E -0.063+0.050 mm from fly ash resulted from combustion of Ekibastuz coal was used as a magnetic component. The surface of magnetic composites was additionally functionalized by grafting of – POONa and – NH2 groups. Under equilibrium conditions sorption capacities of the sorbents with respect to Се3+ used as a U4+/Th4+ simulator and Pb2+ were measured by means of determination of sorption isotherms which were fitted by the Langmuir model. It was established that extraction of Се3+ and Pb2+ from aqueous solutions is characterized by distribution coefficients of 104–106 ml/g. Temperature conditions for solid-phase crystallization of the sorbents resulting in polyphase systems with the content of zircon phase of 50 wt. % were found

Platelet Shape Change and Cytoskeletal Assembly: Effects of pH and Monovalent Cation lonophores

1983 ◽  
Vol 49 (03) ◽  
pp. 230-234 ◽  
Author(s):  
R M Leven ◽  
P A Gonnella ◽  
M J Reeber ◽  
V T Nachmias
Keyword(s):  
Sodium Transport ◽  
Shape Change ◽  
Monovalent Cation ◽  
Extracellular Ph ◽  
Coated Glass ◽  
Effects Of Ph ◽  
Filament Bundles ◽  
Ph Dependent ◽  
Platelet Spreading ◽  
Platelet Shape

SummaryThe monovalent cation ionophores monensin and nigericin cause platelet shape change at a rate of approximately 1/20 of that caused by ADP. The effect of monensin was studied further. Shape change caused by monensin is pH dependent, increasing in rate as extracellular pH increases. Monensin induced shape change is not blocked by 30 μM cinanserin which completely inhibits serotonin induced shape change. Also, the amount of serotonin secreted by monensin treated platelets is below the threshold required to induce shape change. 100 μM ATP which inhibits ADP induced shape change does not affect monensin induced shape change. Amiloride, a sodium transport blocker, inhibits both the rate of ADP induced shape change and platelet spreading on poly-lysine coated glass. Amorphous platelet cyto-skeletons isolated from resting platelets at pH 6.8 with Mg+ + but not Ca++ can be transformed into filament bundles by subsequent incubation at pH 7.6. We conclude that platelet shape change is at least in part triggered by changes in cellular Na+ and pH

scholarly journals Drying kinetics and determination of water sorption isotherms of corn

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
J Roy ◽  
MA Alim ◽  
MN Islam
Keyword(s):  
Moisture Content ◽  
Sorption Isotherm ◽  
Water Sorption ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Drying Kinetics ◽  
Drying Time ◽  
Moisture Sorption Isotherm ◽  
Water Sorption Isotherm ◽  
Monolayer Moisture

The study was carried out for the purpose of determining the drying kinetics as well as moisture sorption isotherm of hybrid-81 corn. Corn at about 31% moisture content (wb) was dried in a forced convective hot air cabinet dryer at different drying conditions, such as variable air dry bulb temperature (40°C, 50°C and 60°C) and loading density (3.56 kg/m2, 7.12 kg/m2, and 10.68 kg/m2) as well as in shining sun at different layers (3.56 kg/m2, 7.12 kg/m2, and 10.68 kg/m2). The water sorption isotherm of the dried corn was developed using vacuum desiccators, which contained saturated salt solutions in the range of 11-93% RHs. The mono-layer moisture content calculated by the Brunauer–Emmett–Teller (BET) model (6.76 g/100 g solid) was lesser than that calculated by the Guggenheim–Anderson–De Boer (GAB) model (10.53 g/100 g solid). The energy constants were 10.45 and 4.64 as per BET and GAB equation, respectively. Both models gave suitable fits for corn. The activation energy (Ea) for diffusion of water was found to be 11.09 kcal/gm-mole for corn. Furthermore, it was noticed that, with the increase of corn layer, the drying rate decreased in case of both sun and mechanical drying. However, higher loading density resulted in efficient drying, at least up to 10.7 kg/m2. It was shown that the drying time to obtain stability was the lowest for moisture content (12.08 %) corresponding to aw of 0.65 in case of BET or GAB monolayer moisture content. This finding could be helpful in predicting the storage life of corn.J. Bangladesh Agril. Univ. 15(2): 309-317, December 2017

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