Effect of pH and ionic strength on ion exchange and chelating properties of an iminodiacetate ion exchange resin with alkaline earth ions

Abstract

useful if the user wishes to have the unknown compared to specific library compounds.(3) A histogram is also presented for each unknown of the number of library compounds which yielded a given value of the disagreement criterion. These compounds satisfy any prefiltering conditions and have been calculated over the requisite mass range. (Compounds which have been rejected because the disagreement criterion exceeded the 10th best member are not included in the histogram.) This feature is particularly useful in determining the distribution of the disagreement criterion beyond the top ten list.

Vertical distributions and speciation of dissolved rare earth elements in the anoxic brines of Bannock Basin, eastern Mediterranean Sea

“…The salinity of the Bannock brine is hard to determine accurately. Bregant et al (1990), using a salinometer after diluting brine samples volumetrically to approximately seawater salinity, reported a brine salinity of 325 on the Practical Salinity Scale, nearly ten times that of the over- of Chelex 100 depend strongly on the ionic strength of the sample (Luttrell et al, 1971 ) 200 mL brine subsamples were diluted with milli-Q water to a total volume of 2 L before adding the spike solution, thereby bringing their ionic strength down to approximately that of seawater. Following preconcentration, the REEs were separated from remaining major cations and Ba, and divided into two fractions (one containing La and some of the Ce and one containing Ce-Lu) with AG 50W-X8 cation-exchange resin, using the method of de , modified after Schijf (1992).…”

The development of an automated HPLC system for the determination of trace-metals in concentrated brines and its application to process monitoring

“…It is well documented [13][14] that the degree of chelation between any given metal ion and a chelating agent is dependent upon the ionic strength and the pH of the sample. In this study the ionic strength of the sample remains fixed with saturated brine i.e.…”

“…As the functional groups of the dye are iminodiacetic acid (IDA) no strong chelation can take place until both groups are in the anionic form [14]. This typically occurs at pH 7.…”

The marine geochemistry of the rare earth elements

“…At pH values over 6 their chelation seems to decrease again. At similar ionic strengths chelation of the alkaline earth metals Ca, ,1g, Sr, Ba also exhibits a plateau at pH between 4 and 5, possibly slightly lower chelation between pH=5 and pH=6 (LUTTRELL et al, 1971) and then a steep increase at higher pH-values. The plateau between pH=5 and pH=6 would then be most suitable for quantitative separation.…”

“…The half-neutralization point (50 % fully dissociated) occurs at pH of about , 1964). At hi gher i oni c strength a11 equilibria shift and chelation becomes effective at lower pH (LUTTRELL et al, 1971). Of course the pH range for chelation is ultimately also a function of the specific affinity of the given metal ion (Mg 2 +, Cu 2 +, Gd 3 +, Th 4 +) for the resin.…”