Determination of Formation Constants of Co￣(2+), Ni￣(2+),Cu￣(2+) and Zn￣(2+) Complexes with Humic and Fulvic Acidsby Potentiometric Titration Method

The formation constants of Co￣(2+), Ni￣(2+), Cu￣(2+) and Zn￣(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof composition of the complexation solutions were obtained by two graphical approaches respectively Theformation constants decreased with increasing concentration of metal in the solution. The results provideunambiguous evidence for the heterogeneity of the function groups of humic substances. The formationconstants of FA were much smaller than those of HA, and the formation constants of Cu￣(2+) were muchgreater than those of Co￣(2+) , Ni￣(2+) and Zn￣(2+) . The potentiometric titration method for determining formationconstants are also discussed in the article.

Determination of Formation Constants of Ce^(3+) Complexes by Fluorescence

Fluorescence of Ce 3+ (aq) is very strong and thoroughly quenched when Ce 3+ forms complexes with ligands containing carboxylate or phosphate groups. This property is employed to develop a new simple method to determine formation constants of Ce 3+ complex system. Fluorescence intensity is used to determine concentration of Ce 3+ (aq) in complex solution, as it is proportional to the concentration of Ce 3+ (aq). In this paper, two examples, Ce 3+ malonic acid and Ce 3+ AMP(adenosine 5′ monophosphate), of fluorescence titration were made and association constants and association numbers of the two systems were deduced for the titration with Scatchard plot. The results are similar to those obtained by others. It is suggested that this Ce 3+ method is a promising fluorescence probe, as it is not only simple but also superior to other lanthanide fluorescence probe in being able to study a large amount of organic ligands and biomolecules.

A Potentiometric Evaluation of Stability Constants of Two-Step Overlapping Equilibria via a Bilogarithmic Hyperbolic Cosine Method

A bilogarithmic hyperbolic cosine method for the evaluation of overlapping formation constants at varying (or fixed) ionic strength is devised in this paper and applied to data reported in the analytical literature, i.e. succinic acid system, Cu(II)-glycine system and Ag(I)-aminobutan-1-ol system. The method is based on the linearization of the formation function ? = f(pH) or ? = f(pL) data. A theoretical slope of unity should be obtained thus proving the correctness of the assumed equilibria. An additional advantage of the bilogarithmic method proposed is that it provides a closed scale representation of Y and X unlike other plots. This paper forms part of an investigation into the uses of bilogarithmic methods and hyperbolic functions in parameter estimation. Methods based on the application of spectrophotometric measurements have been the subject of recent studies.

STUDY ON CONTINUOUS ELECTROREGENERATION OF ION EXCHANGE RESIN

In this Paper, the continuous electroregeneration of ion exchange resin is investegated. The mixed resin is inserted between a canon exchange membrane and an auto n exchange membrane. The effuent water of fresh water room meets the demand for power plant on water treatment. The B_2 that is the cumulative formation constant of the metal complexes of resin is very differente with or without electric fied. It indicates that the dissociation degree of metal complexes of resin is greater hath electric field than that without electric field.

Analysis of Energetic Species Caused by Contact Glow Discharge Electrolysis in Aqueous Solution

Contact glow discharge electrolysis is a non-Faradaic electrochemical process with an abnormal relationship between the current and voltage. Hydroxyl radicals, hydrogen radicals and hydrogen peroxide can be produced under the glow discharge, which are often used to degrade organic contaminants in aqueous solution. In this study, with 4-nitrophenol taken as an example of contaminants and tert-butanol as a scavenger of hydroxyl radicals, the role of energetic species in degrading organic compounds was examined in detail. Moreover, the effects of the applied voltage, solution conductivity and pH on the formation of three energetic species were also observed. The formation rate constants of the three energetic species were calculated based on the experimental data.

Investigation of the interaction of ethyl acetoacetate with nano alumina particle as Lewis acid in acetonitrile solvent

The enol form of ethyl acetoacetate(EAA)displays interesting spectroscopic characteristics;this form of ethyl acetylacetate is very important in condensation reaction.In this investigation,we have studied the interactions and the complex formation constants(K_(f))with nano alumina(10–20 nm)particle and alumina(mesh 135)compounds as Lewis acids in the acetonitrile solvent using absorption spectroscopy and related calculations.Furthermore,in this study we calculated the thermodynamic parameters of this reaction.The trend of reactivity of the ethyl acetoacetate(EAA)complexes toward the above Lewis acids,based on the solvent as follows:nano alumina compound>alumina compound.