Investigation of Complex Formation Process of Copper with Macromolecular Organic Substances, Isolated from Natural Waters

Abstract

Natural macromolecular organic substances-fulvic acids take an active part in complex formation processes and stipulate migration forms of heavy metals in natural waters The calculation of the migration forms of heavy metals is one of the problematic issue of the contemporary chemistry, which couldn’t be solved without using the conditional stability constants of fulvate complexes. In spite of researches, experimental data on stability constants of complex compounds of fulvic acids with heavy metals ( among them copper) are heterogeneous and they differ in several lines from each other. One of the reason of such condition is ignoring an average molecular weight of the associates of fulvic acids, which finally causes the wrong results. Complex formation process between copper (II) and fulvic acids was studied by the solubility method at pH=9.0. Cu(OH)2 suspension was used as a solid phase. Fulvic acids were isolated from Paravani lake by the adsorption –chromatographic method. In this article is shown that, during complex formation process every 1/4 part of an associate of fulvic acids(Mw=7610), inculcates into copper's inner coordination sphere as an integral ligand, so it may assume, that the average molecular weight of the associate of fulvic acids which takes part in complex formation process equals to 1903. This part of the associate of fulvic acids was conventionally called an“active associate".The average molecular weight of the“active associate”was used for determination the composition of copper fulvate complex, the concentration of free ligand and stability constant, which equals to 2,25x107 

Investigation of the Complex Formation Process of Lead (II) with Natural Macromolecular Organic Substances (Fulvic Acids) by the Solubility and Gel Chromatographic Methods

“…For the removing of acetone, the column of activated charcoal was washed by the bidistilled water until the smell of acetone disappeared in eluate. Elution process of FA fraction was performed with 0.1N NaOH solution 7,15 . Obtained alkalic solution of FA, for the purification was passed through a cationexchanger.…”

“…Because it is not possible to calculate concentration of free ligand. 15,20,41 That's why it was necessary to introduce the term-"active associate". 41 But the value of average molecular weight of "active associate" in the case of different metal and pH is dif-ferent.…”

“…4,7,10,11 Carboxyl and phenol groups of FA take an active part in complex formation and sorption processes, proceeding in natural waters, bottom sediments and soils and stipulate migration forms of heavy metals in natural objects. 3,7,[12][13][14][15][16][17][18][19][20][21][22][23] Complex compounds of heavy metals with macromolecular organic substances are characterized with less bioavailability and accordingly with less toxicity. 24,25 Lead is a typical toxic heavy metal which is ubiquitous in natural environment.…”

Measurement of Complex Formation Process of Nickel (II) with Freshwater Fulvic Acids Using the Solubility Method

“…The elemental composition (%) of FA is isolated from natural waters changes C 46.7~59.7; H 4.1~5.5; O 31.8~49.7; N 0.74~3.3 and S 0.4~1.7. 1,[7][8][9][10] FA form stable complexes with heavy metals and radionuclides 1,[11][12][13][14][15][16][17][18][19][20][21] and stipulate migration forms thereof in natural waters and soils. 1,3,[22][23][24][25][26][27] Therefore, FA may affect the transport, accumulation, bioavailability, and toxicity of metals in the environment.…”

Dissociation Constants of Fulvic Acids, Isolated From Natural Waters of Georgia

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Fulvic Acids (FA) are major organic substances dissolved in natural waters (70-80%) [1][2][3]. FA form stable complexes with heavy metals and radionuclides and stipulate migration forms thereof in natural waters and soils [1,2,[4][5][6][7][8][9] . In spite of numerous researches, data about the physical-chemical characteristics of FA are heterogeneous.

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