Variable charges of a red soil from different depths: Acid-base buffer capacity and surface complexation model

The acid-base properties of the glauconite surface has been studied by potentiometric titration. Using a surface complexation model with a constant exchange capacity, it was shown that positively charged surface centers and exchange centers dominate in the acidic pH region, and negatively charged centers dominate in the neutral and alkaline regions. The corresponding constants of acid-base equilibrium have been calculated. The data obtained were used to study the sorption of cadmium and lead on glauconite.

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Approaches to modelling uranium(VI) adsorption on natural mineral assemblages

Radiochimica Acta ◽

10.1524/ract.2000.88.9-11.687 ◽

2000 ◽

Vol 88 (9-11) ◽

Cited By ~ 56

Author(s):

T.D. Waite ◽

James A. Davis ◽

B.R. Fenton ◽

Timothy E. Payne

Keyword(s):

Performance Assessment ◽

Goodness Of Fit ◽

Surface Complexation ◽

Acid Base ◽

Surface Complexes ◽

Natural Mineral ◽

Surface Complexation Model ◽

Surface Sites ◽

Stepwise Manner ◽

Mineral Assemblages

Component additivity (CA) and generalised composite (GC) approaches to deriving a suitable surface complexation model for description of U(VI) adsorption to natural mineral assemblages are pursued in this paper with good success. A single, ferrihydrite-like component is found to reasonably describe uranyl uptake to a number of kaolinitic iron-rich natural substrates at pH > 4 in the CA approach with previously published information on nature of surface complexes, acid-base properties of surface sites and electrostatic effects used in the model. The GC approach, in which little pre-knowledge about generic surface sites is assumed, gives even better fits and would appear to be a method of particular strength for application in areas such as performance assessment provided the model is developed in a careful, stepwise manner with simplicity and goodness of fit as the major criteria for acceptance.

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Acid/base and Cu(II) binding properties of natural organic matter extracted from wheat bran: modeling by the surface complexation model

Water Research ◽

10.1016/s0043-1354(99)00255-9 ◽

2000 ◽

Vol 34 (4) ◽

pp. 1327-1339 ◽

Cited By ~ 49

Author(s):

C Ravat

Keyword(s):

Organic Matter ◽

Natural Organic Matter ◽

Wheat Bran ◽

Surface Complexation ◽

Acid Base ◽

Binding Properties ◽

Surface Complexation Model

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THE CONTRIBUTION OF LACTATE AND PHOSPHATE ANIONS TO THE BUFFER PROPERTIES OF TISSUE HOMOGENATES OF BREAST ADENOCARCINOMA

Problems in oncology ◽

10.37469/0507-3758-2019-65-5-684-690 ◽

2019 ◽

Vol 65 (5) ◽

pp. 684-690

Author(s):

Margarita Barsukova ◽

Yekaterina Khomutova ◽

Yevgeniy Khomutov

Keyword(s):

Mammary Gland ◽

Buffer Capacity ◽

Tumor Tissue ◽

Mammary Adenocarcinoma ◽

Breast Adenocarcinoma ◽

Acid Base ◽

Adjacent Tissue ◽

Tumor Tissues ◽

Tissue Homogenates ◽

Phosphate Anions

The article discusses the role of conjugated lactic acid/ lactate anion (LacH/Lac-) and dihydrogenphosphate anion/ hydrogenphosphate anion (H2PO4-/HPO42-) pairs in the formation of the buffer properties of tissue as a factor determining pH. The buffer properties of homogenates of the tissue of adenocarcinoma of the mammary gland and the adjacent tissue were quantitatively characterized by the buffer capacity which was determined by potentiometric titration. The concentrations of acid anions were determined spectrophotometrically. The material was biopsy specimens of mammary gland adenocarcinoma (T1-4, N0-1, M0) and adjacent tissue of 22 patients aged from 33 to 75 years. It was found that the buffer capacity of tumors is in 2.5 times higher than in normal tissue. It was established that for the tumor tissue, the buffer capacity of the LacH/Lac- system is in 3 times higher, and the buffer capacity of the H2PO4-/HPO42-system is in 2.5 times greater than for normal untransformed tissue. Concentrations of lactate anions (1,93 ± 0,50 vs 0,57 ± 0,22; p <0.001) and phosphate anions (2,54 ± 0,39 vs 0,70 ± 0,19; p <0,001) in homogenates of the tumor tissue were significantly higher in tumor tissue in comparison with the adjacent tissue. A strong correlation was found between the concentration of phosphate anions and the buffer capacity for tumor tissue (r = 0,857; p = 0,002) and for adjacent tissue (r = 0,917; p <0,001). The correlation between the concentration of lactate anions and the buffer capacity for tumor tissues can be estimated as average (r = 0,626; p = 0,053), while it is absent for the adjacent tissue (r = 0,494; p = 0,147). The results suggest that the acid-base properties of homogenates of mammary adenocarcinoma tissues are determined by two buffer systems: LacH/Lac- and H2PO4-/HPO42-, while the intracellular acid-base homeostasis of non-transformed tissues is mainly determined by the H2PO4-/HPO42- system.

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Comparison of a Non Electrostatic Surface Complexation Model and Surface Phase Theories for Prediction of Future Sorption Properties.

MRS Proceedings ◽

10.1557/proc-824-cc7.2 ◽

2004 ◽

Vol 824 ◽

Author(s):

Allan T. Emrén ◽

Anna-Maria Jacobsson

Keyword(s):

Aqueous Solution ◽

Chemical Potential ◽

Surface Complexation ◽

Sorption Properties ◽

Phase Method ◽

Detailed Knowledge ◽

Surface Phase ◽

Surface Complexation Model ◽

Advantages And Disadvantages ◽

The One

AbstractIn performance assessments, sorption of radionuclides dissolved in groundwater is mostly handled by the use of fixed Kd values. It has been well known that this approach is unsatisfying. Only during the last few years, however, tools have become available that make it possible to predict the actual Kd value in an aqueous solution that differs from the one in which the sorption properties were measured.One such approach is surface complexation (SC) that gives a detailed knowledge of the sorption properties. In SC, one tries to find what kinds of sorbed species are available on the surface and the thermodynamics for their formation from species in the bulk aqueous solution. Recently, a different approach, surface phase method (SP), has been developed. In SP, a thin layer including the surface is treated as a separate phase. In the bulk aqueous solution, the surface phase is treated as a virtual component, and from the chemical potential of this component, the sorption properties can be found.In the paper, we compare advantages and disadvantages of the two kinds of models. We also investigate the differences in predicted sorption properties of a number of radionuclides (Co, Np, Th and U). Furthermore, we discuss under which circumstances, one approach or the other is preferable.

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