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| 2. |
- Lützenkirchen, Johannes, et al.
(författare)
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Potentiometric titrations as a tool for surface charge determination
- 2012
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Ingår i: Croatica Chemica Acta. - : Croatian Chemical Society. - 0011-1643 .- 1334-417X. ; 85:4, s. 391-417
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Tidskriftsartikel (refereegranskat)abstract
- This article summarizes methods for determining proton surface charge at mineral/water interfaces. It covers conventional experimental procedures and discusses problems with the techniques. Also it involves recommendations for obtaining reasonable and comparable results. The term "comparable results" refers to comparison between results for the same solid as obtained in different laboratories. The most important parameters for the surface titrations are discussed. We also propose a reference titration procedure that would allow direct, unbiased comparisons of experimental data. The article finally includes a check-list for researchers and reviewers which should allow limiting the amount of titration data that are not useful for future uses.
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| 3. |
- Olovsson, Ivar
(författare)
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The Electron Density of the Hydrogen Bond
- 1982
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Ingår i: Croatica Chemica Acta. - 0011-1643 .- 1334-417X. ; 55:1-2, s. 171-190
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Stenius, P, et al.
(författare)
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Nonionic hydrophilic surfaces: adsorption and interactions
- 1990
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Ingår i: Croatica Chemica Acta. - 0011-1643 .- 1334-417X. ; 63, s. 501-516
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Tidskriftsartikel (refereegranskat)abstract
- An overview is given of recent studies of nonionic, hydrophilic surfaces formed by the adsorption surfactants or surface active polymers. Hydrophobic surfaces can be easily hydrophilized by the adsorption of nonionic surfactants or block copolymers containing hydrophobic chain segements; the cooperative interaction between the hydrocarbon moieties contributes more to the free energy of adsorption than the interaction with the hydrophobic surface. Hydrophilic layers are also readily formed on hydrophilic surfaces provided specific interaction between the hydrophilic end groups and the surface creates a sufficiently hydrophobic surface so that a second layer can bed formed through cooperative interaction. The temperature dependence of the interaction forces between layers of surfactants can be closely correlated with their phase equilibria with water. In order to prevent protein adsorption the surface should be neither charged nor hydrophobic; it is shown that, accordingly, protein adsorption is extremely low on poly ethylene oxide-covered surfaces.
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| 5. |
- Zeiner, Michaela, 1973-, et al.
(författare)
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Availability of Selected (Pollutant) Elements and their Influence on Soil Composition in Urban Area
- 2015
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Ingår i: Croatica Chemica Acta. - : The Croatian Chemical Society. - 0011-1643 .- 1334-417X. ; 88:1, s. 23-33
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Tidskriftsartikel (refereegranskat)abstract
- Interest in growing fruits and vegetables in private gardens is rising due to nowadays ecological awareness. Avoiding artificial fertilizers and plant protection products does not guarantee the absence of toxic substances, especially heavy metals in the soil and thus in the fruits harvested. Due to either geological bedrock weathering or environmental pollution, garden soils may be rich in certain potentially toxic elements. In the present study ten garden soils from central Croatia have been analysed by the BCR method for the contents and bioavailability of aluminium, cadmium, chromium, cobalt, copper, lead, manganese, nickel and zinc. The total amounts of the elements are in the concentration range as reported for agricultural soils in different geographical regions. Only two soils of the capital Zagreb have higher concentrations of pollutant metals, such as chromium, cobalt, copper, lead, manganese and zinc. Regarding nutrients, all soils have met the needs of common garden plants.
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| 6. |
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| 7. |
- Horváth, László, et al.
(författare)
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Precipitation and Characterization of Two Novel Aluminum Hydroxo Phthalates Formed in the Presence of Silicic Acid
- 2004
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Ingår i: CROATICA CHEMICA ACTA. - 0011-1643. ; 77:3, s. 469-76
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Tidskriftsartikel (refereegranskat)abstract
- The present work, performed at constant ionic strength of 0.6 mol dm(-3) NaCl at 25 degreesC, is a continuation of long-term studies of the conditions necessary for initial clay formation in model systems containing organic acids, Al and Si. Solid phases and the precipitation boundary characterizing the system H+-Al3+-phthalic acid (H2L)-silicic acid were determined and compared with the previously found compound Al-2(OH)(4)L (-) 4H(2)O (A) of a monoclinic unit cell, which was formed in the absence of Si. Addition of Si induced precipitation of two novel compounds (B and C) of the orthorhombic unit cell. Compound B was formed at a low L/Al ratio (R less than or equal to 2) and was of variable composition: AlxSi1.450-0.725 (OH)(3.8+/-0.1x) L(.)6H(2)O. It was found by calculation that at R less than or equal to 2 the end member with x = 2, Al-2(OH)(4)L (.) 6H(2)O, determined the precipitation boundary. Compound C formed at R > 2 had the constant composition Al(OH)L (.) 3H(2)O. Formation constants beta(p,q,r) were determined for the general equation pH(+) + qAl(3+) + rL(2-) --> HpAlqLr. The obtained values for compounds B and C are: log beta(-4, 2, 1) = -7.40+/-0.10 and log beta (-1, 1, 1) = 1.55 +/- 0.05, respectively. In addition to chemical analysis, thermogravimetry (TG), X-ray diffraction (XRD), infrared spectroscopy (IR), solid state Al-27 MAS NMR, Si-29 MAS NMR and Na-23 MAS NMR techniques were used for better characterization of solids and to detect possible impurities in them. Aluminum was found to be hexa-coordinated in all compounds. The IR spectra suggest that the phthalate ion acted as a bidendate ligand, bridging two aluminum atoms in solids B and C.
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