Sulfate-selective Electrode Based on a Complex of Copper

Abstract

Sulfate is a major anion with relevance to industrial chemistry, environmental chemistry including pollution studies, biochemistry and mineralogy, as well as several other areas. The fact that sulfur in several other forms is ultimately determined after conversion to sulfate further enhances the importance of sulfate determination. Acid rain is a very serious problem closely connected with the fast development of industries and economics in the world. In order to clarify and evaluate the effect of acid rain on the acidification of the natural environment, the development of chemical sensors for measuring the primary components of acid rain is important.Among chemical sensors ion-selective electrodes (ISEs) are mainly used for routine applications because they have a number of advantages over other methods of ion determination, such as analysis speed, portability, no sample destruction, and a wide measuring range. The essential property of ISEs is their selectivity, except for cases in which they are employed as detectors in connection with a separation method. In such a case, the best performance does not require selectivity, but only a short response time.Although the majority of the approximately 60 ions for which ionophore based polymeric membrane ion-selective electrodes have been described up to now are cations, 1,2 a series of a new anion-selective electrodes were introduced recently as a result of the growing interest in the host-guest chemistry of anions. [3][4][5] Classical liquid membrane electrodes for anions are based on quaternary ammonium salts and exhibit the Hofmeister selectivity sequence based on the analyte lipophilicity. 6,7 Recently, a series of new anion-selective electrodes has been described, which display a selectivity deviating from the Hofmeister sequence as a result of unique interactions between the carriers and the anions. It has been well documented that the selective complexation of anions by synthetic ionophores can be used to design anion selective electrodes. For sulfate, so far, the most promising ISE is based on a bis(thiourea) derivative that forms four hydrogen bonds in a 1:1 complex with sulfate. 8 Recently, a bis(imidazole) derivative was reported to exhibit a similar selectivity for sulfate with respect to major interferences along with a strong pH dependence. 9 The synthetic hydrotalcite have been used as ionophore for sulfate. 10 For a truly anion-selective electrode, a strong interaction between the ionophore and the anion is required in order to complex the anion in a selective fashion. The potentiometric response of the membranes doped with these complexes is believed to be based on the coordination of analyte anion axial ligand to the metal center of the carrier molecule. 11,12 Recently, we have used ionophores in the construction of ISEs for NO3 -13,14 and SCN -. 15 In the present paper, we report the use of N,N′-bis(2-amino-1-oxo-phenelenyl)phenylenediamine copper(II) as an excellent ionophore for the preparation of a high selective ISE for the potentiometric det...

Spectrophotometric determination of nitrite by its catalytic effect on the oxidation of congo red with bromate

“…When the nitrite ion catalyzes this reaction, the oxidation of CR is much faster, resulting in a considerable discoloration of mixture (Figure 1). For the oxidation of organic compounds (OC), the following reactions can describe the role of nitrite as a catalyst in the presence of bromate [36] After scanning the spectrum of CR in acid medium, in the wavelength range 450-650 nm, the wavelength of maximum absorbance attributed to CR was found to be λ max = 570 nm.…”

A novel zeolite-multiwalled carbon nanotube composite for the electroanalysis of copper(II) ion

“…Zeolites X, Y and 13X were also investigated for the determination of Cu 2? ion [33][34][35][36][37]. Walcarius showed that between ZMCPE and zeolite monograin layers coated on GCE, the former presented a better current response to Cu 2?…”

Different Electrocatalytic Response Related to the Morphological Structure of TiO2 Nanomaterial: Hydroquinone as an Analytical Probe

“…Nanomaterialh as attracted much attention because of their differenta nd superior properties compared to the bulk phase.E lectronic and optical properties of nanomaterial led to their usage in the field of photocatalysis,p hotovoltaic, sensing, and photonicc rystals [1][2][3][4][5][6].T itanium is the ninth most plenty of element in the Earthsc rust. TiO 2 ,acompound of titanium, is used in many applications from photocatalyst, self-cleaning coatings,a nd paints to solar cells and anticorrosion [7][8][9][10].O ne-dimensional nanostructures such as TiO 2 nanowires,n anorods, nanotubes,n anofiber and their composites with TiO 2 nanoparticles have been reviewed to improve the electron mobility and transport rate [11,12].T iO 2 nanoparticles have superp erformancea nd broada pplications as ap hotocatalyst and catalyst, in solar cells,g as sensors,p igments and other devices [13].D ue to the great oxidizing power, high electro stability,r edox selectivity and easy synthesis of TiO 2 ,i ti sv astly used in electrocatalytic applications [14][15][16][17].T he electrochemical behavior of TiO 2 depends on the crystal structure, surface properties and textural properties such as specific surface area, size,v olumea nd distribution. Many attempts have been created to synthesize TiO 2 with ac ontrollable morphology and facet of structure [18,19].T iO 2 nanoparticles have been combined with other compounds such as graphite and carbonn anotubes to make nanocomposite in the electrochemical analysis in order to determine some of biological compounds [ 20,21] TiO 2 nanomaterials include nanoparticles,n anotubes, nanofibers or theirc omposites can be prepared by many different methods [ 22].A mong these methods, it seems that electrospinning provides the simplest approach to form nanofibers,m icrofibers,n anowires,a nd other nanostructures for different applications.A dvantages of electrospinning method are as follows:1 )L arge specific surface area and pore dispensationo fe lectrospun nanofibers 2) this method is suitable for produce nanostructures an industriall evel, and 3) it is as imple and multifunctional method to formu ltrathin fibers under the influence of an electrostatic field [23-25].T he diametero ft he electrospun nanofibers can be easilyc ontrolled in the range of less than tens of nanometers,w hich is still ab ig problem for other methods.T he electrospinning uses asingle capillarya st he spinneret, which is only appropriate to generate with one particular composition …”