The Application of a Simple Chemical Model of Natural Waters to Metal Fixation in Particulate Matter

1975 ◽  
Vol 53 (5) ◽  
pp. 661-669 ◽  
Author(s):  
Robert D. Guy ◽  
C. L. Chakrabarti ◽  
Laurier L. Schramm
Keyword(s):  
Humic Acid ◽  
Natural Waters ◽  
Anodic Stripping Voltammetry ◽  
Copper Ion ◽  
Freundlich Isotherm ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Chemical Model ◽  
Organic Complexes ◽  
Simple Chemical

A simple chemical model was used to investigate the mechanisms controlling the distribution of metals between soluble and particulate fractions in natural waters. The model particulates used were potassium bentonite, hydrous MnO2, and solid humic acid. The soluble species in natural waters were modelled by soluble humic acid, tannic acid, and bicarbonate. The sorption curves for Cu(II), Cd(II), and Zn(II) onto humic acid and MnO2 obeyed Langmuir adsorption isotherms whereas the sorption of the above ions onto bentonite followed a Freundlich isotherm. Chemical analysis of the total model using atomic absorption spectroscopy and differential pulse anodic stripping voltammetry indicated that copper distribution depends on the pH of the suspension: above pH 6.0, 50 % of the copper is sorbed onto the particulates whereas the copper in solution is in a complexed form; between pH 6 and 3.8 the soluble copper is distributed between organic complexes and "free" copper ion; between pH 4.2 to 2.5 copper is being desorbed from the particulates; and below pH 2.5 all the copper is present in solution as "free" copper ion.

scholarly journals Employment of Peak Area as Instrumental Datum for Improving the Voltammetric Quantitative Analysis of Heavy Metals in Fresh and Sea Water in the Presence of Surfactants

2002 ◽  
Vol 85 (1) ◽  
pp. 233-242 ◽  
Author(s):  
Clinio Locatelli
Keyword(s):  
Heavy Metals ◽  
Natural Waters ◽  
Sea Water ◽  
Anodic Stripping Voltammetry ◽  
River Mouth ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Standard Reference Materials ◽  
Po River ◽  
Relative Standard

Abstract Peak area instead of peak height is used for the simultaneous determination of Cu(II), Pb(II), Cd(II), and Zn(II) in fresh and sea water in the presence of anionic and cationic surfactants by differential pulse anodic stripping voltammetry. These species, if present, tend to make more irreversible the electrodic process of the metals. Because the employment of peak area for species having irreversible electrodic processes permits limits of detection about one or 2 orders of magnitude lower, this work shows the possibility of determining heavy metals at ultratrace level concentrations in the presence of surfactants, compounds which are always present in natural waters. The precision and accuracy of the analytical method were checked by the analysis of the standard reference materials (SRM) Fresh Water NIST-SRM 1643d, Sea Water BCR-CRM 403, and Estuarine Water BCR-CRM 505. The former, expressed as relative standard deviation (sr), and the latter, expressed as relative error (e), were satisfactory, being in all cases lower than 5%. The analytical procedure has been applied to fresh and sea water sampled in the Po river mouth area (Italy).

Sign in / Sign up

Export Citation Format

Share Document