Asymmetrical Schiff Bases as Carriers in PVC Membrane Electrodes for Cadmium (II) Ions

Abstract

5-[((4-Methyl phenyl) azo)-N-(6-amino-2-pyridin) salicylaldimine] (S 1 ), and 5-[((4-methyl phenyl) azo)-N-(2-diamino-2-cyano-1-ethyl cyanide) salicylaldehyde] (S 2 ) with N and O donor atoms are effective ionophores to make Cd 2þ -selective membrane electrodes. The electrodes based on S 1 and S 2 exhibits a Nernstian or near-Nernstian response for cadmium ion over a wide concentration range 1.5 Â 10 À1 -7.5 Â 10 À7 with a slope of 28 and 2.0 Â 10 À1 -4.0 Â 10 À7 with a slope of 22, respectively. They have quick response and can be used for three or four months without any divergence in potential. The proposed sensors show fairly good selectivity over some alkali, alkaline earth, transition and heavy metal ions. The electrodes based on S 1 and S 2 can be used in the pH range 3.5 -9. These electrodes were used as an indicator electrode in potentiometric titration of cadmium ion with EDTA and in the direct determination of cadmium ion in aqueous solutions.

Preparation and properties of novel sol-gel-derived quaternized poly(n-methyl pyrrole)/Sn(II)SiO3/CNT composites

“…If the slope of a species is close to Nernstian value, it would be more selective as compared to others having a deviated slope [35][36][37][38][39]. The comparative Table 3 is given for all the parameters for Cd(II) ionselective membrane electrode [40][41][42][43][44][45][46][47][48][49].…”

Novel PVC-membrane potentiometric sensors based on a recently synthesized sulfur-containing macrocyclic diamide for Cd2+ ion. Application to flow-injection potentiometry

“…It is well understood that the sensitivity, linearity and selectivity obtained for a given ionophore depends significantly on the membrane composition [9][10][11][12][13][14][15][16][17][18][19][21][22][23][24][25][26][27][28]. Thus, different compositions of the membrane preparation based on ionophore L were examined in order to obtain the optimized membrane composition, and the results are summarized in Table 1.…”

“…Thus, due to urgent need for Cd 2+ -selective sensors for potentiometric monitoring of cadmium ions in chemical, industrial and environmental sample, in recent years, a number of ion-selective electrodes for cadmium assay have been reported in the literature [21][22][23][24][25][26][27][28][29][30][31][32][33][34]. However, most of these electrodes suffer from one or more of the following drawbacks: lack of stability and selectivity, limited concentration range and small range of working pH, relatively long response time and considerable interferences from other cations such as Ag + , Zn 2+ , Cu 2+ , Pb 2+ and Hg 2+ .…”

Ion-exchange studies on poly-o-anisidine Sn(IV) phosphate nano composite and its application as Cd(II) ion-selective membrane electrode

“…13). The amount of Cd(ІІ) ions in solution can be accurately determined from the resulting neat titration curve providing a sharp rise in the titration curve at the equivalence points A comparative study of various Cd(II) ion selective membrane electrodes is given in Table 8 [36][37][38][39][40][41][42], wherein data from literature of different Cd(II) ion selective membrane electrode is compared to data obtained with poly-o-anisidine Sn(IV) phosphate. The presented membrane electrode showed faster response with respect to any other Cd(II) ion-selective membrane electrode.…”