Development of highly sensitive cadmium iondashselective electrodes by titration method and its application to cadmium ion determination in industrial waste water.
Characteristics of cadmium iondashselective electrode made cadmium sulphide (CdS)-silver sulphide (Ag(2)S) mixture were studied. CdS-Ag(2)S mixtures were obtained by gas/solid-phase reaction between silver-cadmium mixed powder and hydrogen sulphide gas (dry method) and by ionic reaction between cadmium-silver mixed ions and sulphide ion (wet method). As a result, it was found that the CdS-Ag(2)S mixture had to be made in the condition of excess existence of sulfur and had better regulate the excess sulfur quantity minimum, for the CdS-Ag(2)S pressed membrane gave a good Nernstian response against the cadmium ion concentration change. As the best way, CdS-Ag(2)S mixture was obtained by adding sulphide ion solution to 5 mol% cadmium ion and 95 mol% silver ion mixed solution while measuring silver sulphide (Ag(2)S) electrode potential as an indicator electrode. According to the reaction was stopped when the potential variation from the initial potential in the sulphide ion solution reached at 87-116 mV which the sulphide ion concentration became 10(-3) - 10(-4) of the initial concentration, the cadmium ion membrane pressed diameter of 8 mm and thickness of 2 mm showed a Nernstian response from 10(-8) to 10(-1) M of cadmium ion concentration. Furthermore, aiming to its application for industrial waste water, masking buffer for interfering metal ions such as lead ion (Pb(2+)) and copper ion (Cu(2+)), which were possibly coexisted and to adjust total ionic strength and pH of sample was developed. The present Cd(2+) iondashselective electrode was applied to the determination of Cd(2+) in the industrial waste water. The good regression line with correlation factor of 0.984 was obtained compared with the conventional atomic absorption spectroscopy.
Characterization of Silver Sulphide Thin Films Prepared by Spray Pyrolysis Using a New Precursor Silver Chloride
Silver sulphide is a semiconductor widely used as an infrared sensor and as an absorber material for solar cells. In this work, we report the preparation of Ag2S thin films from a new precursor using chemical spray pyrolysis technique. The thin films having various (CS(NH2)2)/(AgCl) were grown at different substrate temperatures and characterized using X-Ray diffraction, Scanning Electron Microscopy, transmission T(λ) and reflectivity R(λ) measurements. The diffraction patterns showed that the sample having x =(CS(NH2)2)/(AgCl)=5 ratio at the substrate temperature Ts =200 °C has the best crystallinity and exhibits a monoclinic structure preferentially oriented in the direction of (-112) lattice plan . The optical properties have been investigated using spectrophotometric measurements in the wavelength range 200-2500 nm. The obtained values of the band gap energy were in the order of 1 eV. The refractive index n and the extinction coefficient k were determined from the absolute values of the measured transmittance and reflectance. The conductivity at room temperature was 32×10 - 3 (Ω cm) -1 , and the films were n type. Copyright © 2014 IFSA Publishing, S. L.
Copper(I) sulfide ceramic membranes as selective electrodes for Copper(II)
Abstract A new type of copper(II)-selective electrode has been developed, based on copper(I) sulfide ceramic membranes prepared by an annealing process. The response time was very short even at low concentrations and the potentials were steady and reproducible. The Nernst equation was obeyed in the concentration range of 10 -1 –10 -6 M copper(II) and the analytical range was 10 -1 –10 -8 M . Among the common ions, silver, ammonium, iron(III) and iodide interfered.