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The effect of pH on the sorption of copper ions by alginates

100%
Kwiatkowska-Marks S., Miłek J., Wójcik M.
Polish Journal of Chemical Technology
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2008
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vol. 10
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issue 1
28-30
EN
The effect of pH on copper ions sorption by alginates has been investigated. The granules of the sorbent obtained from sodium alginate (type DMF, manufactured by KELCO) have been applied. By using a new method of gelation a biosorbent containing from 11.3 to 20.3% mas. of alginate has been produced. Investigations have been carried out at a constant temperature of 25°C and the pH values ranging from 3 to 5. The obtained experimental results have been described by the Langmuir equation. It has been found that with the increasing pH of the solution the maximum biosorbent sorption capacity increased.
2
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The Formation of Polycomplexes of Poly(Methyl Vinyl Ether-Co-Maleic Anhydride) and Bovine Serum Albumin in the Presence of Copper Ions

86%
Karahan M., Mustafaeva Z., Özeroğlu C.
Polish Journal of Chemical Technology
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2014
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vol. 16
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issue 3
97-105
EN
The binary and ternary complex formations of poly(methyl vinyl ether-co-maleic anhydride) (PMVEMA) with copper ions and with bovine serum albumin (BSA) in the presence of copper ions in phosphate buffer solution at pH = 7 were examined by the techniques of UV-visible, fluorescence, dynamic light scattering, atomic force microscopy measurements. In the formation of binary complexes of PMVEMA-Cu(II), the addition of copper ions to the solution of PMVEMA in phosphate buffer solution at pH = 7 forms homogeneous solutions when the molar ratio of Cu(II)/MVEMA is 0.5. Then the formations of ternary complexes of PMVEMA-Cu(II)-BSA were examined. Study analysis revealed that the toxicities of polymer-metal and polymer-metal-protein mixture solutions depend on the nature and ratio of components in mixtures.
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Generation of ·OH initiated by interaction of Fe2+ and Cu+ with dioxygen; comparison with the Fenton chemistry.

72%
Urbański N. K., Beręsewicz A.
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2000
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vol. 47
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issue 4
951-962
EN
Iron and copper toxicity has been presumed to involve the formation of hydroxyl radical (·OH) from H2O2 in the Fenton reaction. The aim of this study was to verify that Fe2+-O2 and Cu+-O2 chemistry is capable of generating ·OH in the quasi physiological environment of Krebs-Henseleit buffer (KH), and to compare the ability of the Fe2+-O2 system and of the Fenton system (Fe2+ + H2O2) to produce ·OH. The addition of Fe2+ and Cu+ (0-20 μM) to KH resulted in a concentration-dependent increase in ·OH formation, as measured by the salicylate method. While Fe3+ and Cu2+ (0-20 μM) did not result in ·OH formation, these ions mediated significant ·OH production in the presence of a number of reducing agents. The ·OH yield from the reaction mediated by Fe2+ was increased by exogenous Fe3+ and Cu2+ and was prevented by the deoxygenation of the buffer and reduced by superoxide dismutase, catalase, and desferrioxamine. Addition of 1 μM, 5 μM or 10 μM Fe2+ to a range of H2O2 concentrations (the Fenton system) resulted in a H2O2-concentration-dependent rise in ·OH formation. For each Fe2+ concentration tested, the ·OH yield doubled when the ratio [H2O2]:[Fe2+] was raised from zero to one. In conclusion: (i) Fe2+-O2 and Cu+-O2 chemistry is capable of promoting ·OH generation in the environment of oxygenated KH, in the absence of pre-existing superoxide and/or H2O2, and possibly through a mechanism initiated by the metal autoxidation; (ii) The process is enhanced by contaminating Fe3+ and Cu2+; (iii) In the presence of reducing agents also Fe3+ and Cu2+ promote the ·OH formation; (iv) Depending on the actual [H2O2]:[Fe2+] ratio, the efficiency of the Fe2+-O2 chemistry to generate ·OH is greater than or, at best, equal to that of the Fe2+-driven Fenton reaction.
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