Evaluation of the copper anodic stripping voltammetry complexometric titration for complexing capacities and conditional stability constants

1981 ◽  
Vol 53 (13) ◽  
pp. 1986-1989 ◽  
Author(s):  
John R. Tuschall ◽  
Patrick L. Brezonik
Keyword(s):  
Stability Constants ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Conditional Stability ◽  
Complexometric Titration ◽  
Anodic Stripping ◽  
Conditional Stability Constants

Heavy metal (Zn and Cu) complexation and molecular size distribution in wastewater treatment plant effluent

2008 ◽  
Vol 58 (6) ◽  
pp. 1207-1213 ◽  
Author(s):  
G. G. T. Chaminda ◽  
F. Nakajima ◽  
H. Furumai
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Anodic Stripping Voltammetry ◽  
Treatment Plant ◽  
Molecular Size ◽  
Stripping Voltammetry ◽  
Conditional Stability ◽  
Conditional Stability Constant ◽  
Conditional Stability Constants ◽  
Molecular Size Distribution

The size distributions of zinc and copper species in the effluent of a wastewater treatment plant were determined by a combination of ultrafiltration and chelating disk cartridge fractionation. The results showed that 75–87% of total Zn and 84–86% of total Cu were strongly complexed or particle-bound in the final effluents. It was also found that the major part of Cu was bound to ligands in the <500 Da fraction while the trend for Zn was not so clear and exhibited significant seasonal variability. Labile Cu and Zn were detected not only in the smallest fraction (<500 Da) but also in the larger fractions. It meant that the labile species in the effluent were not equivalent to free metal ions. Conditional stability constants and ligand concentrations were also determined from the measured metal concentrations by square wave anodic stripping voltammetry. Existence of two types of ligand for each metal was inferred from the experimental data. Conditional stability constant obtained for the stronger type Ligand of Zn was higher than that of Cu, although the estimated Ligand concentrations were almost similar.

Direct measurement of equilibrium constants for water-soluble porphyrin with copper(II) and cobalt(II) by differential pulse anodic stripping voltammetry (DPASV)

2012 ◽  
Vol 16 (02) ◽  
pp. 235-243
Author(s):  
Md. Shahajahan Kutubi ◽  
Masaaki Tabata
Keyword(s):  
Detection Limit ◽  
Metal Ions ◽  
Stability Constants ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Water Soluble ◽  
Working Electrode ◽  
Anodic Stripping ◽  
The Stability

Because of high stability constants and slow metalation rate of porphyrins, it is difficult to determine stability constants of metalloporphyrins correctly. We propose here a new method for the determination of the stability constant of Cu(II) or Co(II) with 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin, H2(OBTMPyP(4))4+ , by differential pulse anodic stripping voltammetry (DPASV) using a gold working electrode. The concentrations of free Cu(II) or Co(II) ion as low as 10-7–10-8 M were determined directly in equilibrium with H2(OBTMPyP(4))4+ of 10-7–10-8 M under optimum DPSAV conditions of rotating disk gold electrode, deposition of metals, stripping of metals, potential pulse amplitude and pulse width. Furthermore effects of supporting electrolytes, time for the attainment of chemical equilibrium and determination methods (standard addition and calibration curve methods) of total free metal ions were considered. Tetramethylammonium chloride, (CH3)4N+Cl-(TMAC) , showed the lowest detection limit of metals among other electrolytes such as Na2SO4 , NaNO3 , NaCl : 0.5 ppb for Cu(II) at I = 0.1 ((CH3)4N+Cl-) . The stability constants of K s defined as M2+ + P2- = MP ( M = Cu(II) and Co(II) , and H2P = H2(OBTMPyP(4))4+ ) were 1013.93 and 109.47 M-1 for Cu(II) and Co(II) , respectively, at I = 0.1 (CH3)4N+Cl-) and 25 °C. The working electrode was also electrochemically activated at higher potential affording to lower detection limit of metal ions as well as to measure cyclic voltammetry of metal ions, porphyrin and metalloporphyrin as low as 10-5 M. The values of E ap (vs. Ag/AgCl ) of Cu2+ , H2(OBTMPyP(4))4+ and Cu(OBTMPyP(4))4+ were 345, 338 and 425, respectively.

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