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Abstract The title of the thesis (potentiometric determination of some compounds and their environmental applications) Ion-selctive membrane-electrodes (ISEs) are a well-established electro-analytical technique which used in quantitative analysis. An ion-selective electrode (ISE), also known as (a specific ion electrode) is a sensor that converts the activity of a specific ion dissolved in a solution into an electrical potential, which can be measured by a voltmeter or pH meter. The voltage is theoretically dependent on the logarithm of the ionic activity, according to the Nernst equation. The sensing part of the electrode is usually made as an ion-specific membrane, along with a reference electrode. Since the end of the 1960s, ion-selective electrodes have continued to be an important development in analytical chemistry. Polymer membrane ion sensors in particular find extensive practical applications, especially in medicinal, agricultural, environmental and different industrial analysis. Ion-selective electrodes are used in a wide variety of applications for determining the concentrations of various ions in aqueous solutions. The following is a list of some of the main areas in which ISEs have been used. • Pollution monitoring: CN, F, S, Cl, NO3 etc., in effluents, and natural waters. • Agriculture: NO3, Cl, NH4, K, Ca, I, CN in soils, plant material, fertilizers and feedstuffs. • Food processing: NO3, NO2 in meat preservatives. Summary 108 • Salt content of meat, fish, dairy products, fruit juices and brewing solutions. • F in drinking water and other drinks. • Ca in dairy products and beer. • K in fruit juices and wine making. • Corrosive effect of NO3 in canned foods. • Detergent manufacture: Ca, Ba, F for studying effects on water quality. • Paper manufacture: S and Cl in pulping and recovery-cycle liquors. • Explosives: F, Cl, NO3 in explosive materials and combustion products. • Electroplating: F and Cl in etching baths; S in anodizing baths. • Biomedical laboratories: Ca, K, Cl in body fluids (blood, plasma, serum and sweat). • F in skeletal and dental studies. • Education and Research: Wide range of applications. ISEs offer several advantages as well size, simplicity of operation and low cost per sample. Besides, they are ideally suited for onsite analysis. The thesis consists of three parts: Part I: Introduction • How dangerous pollutants especially heavy metals on the environment, the great concern of society about environmental pollution especially water pollution, increasing interest in the qualitative and quantitative determination of specific metal species as result of the growing awareness of the strong dependence of the heavy metals Summary 109 • Include a general introduction on ion selective electrode such as classification, mechanism of response of ion selective electrodes, measuring range, detection limit, selectivity, slope, response time membrane components of ion-selective electrode, theoretical principles, and some strategies used in fabrication of ion-selective electrodes toward main group cations. • Survey about various analytical techniques which have been proposed for determinations of copper and cobalt. Part II: Experimental Include apparatus, reagents and materials used, preparation of ionophors, preparation of ion-selective membranes for cobalt and copper ions, characterization the properties of the prepared electrodes, environmental applications of the prepared electrodes and comparison the results with atomic absorption spectroscopic results. Part III: Result and discussion Simple and direct potentiometric method for determining Cu2+ is described based on the use of Cu2+ complex of 4-azocyanoacetamido-mtoludine antipyrine as ionophore. poly(vinyl chloride), the membrane containing NaTPB as anionic additive and o-NOPE, DOP and DOS as plasticizers. The three prepared electrodes was calibrated by measuring the e.m.f values after stabilization to ± 0.5 mV in a series of Cu2+ solutions covering the concentration range 1.0×10−6 M to 1.0×10−2 M Cu2+. The e.m.f values were plotted on a semi logarithmic paper as a function of Cu2+ concentration. The obtained calibration curve was used for subsequent determination of the unknown Cu2+ ion samples. The selectivity coefficients for foreign ions were determined by the separate solution Summary 110 method (SSM) in which the potential readings (mV) of the two separate solutions one containing only the Cu2+ ion at the concentration level of 10−3 M and the other containing the interferents ions(10-2 - 10-6 M). The response time of the proposed electrode was also, tested by measuring the time required to achieve a 95% steady potential for the test solutions, when the Cu2+ ions concentration were rapidly increased by one decade from 1.0×10−6 M to 1.0×10−2 M. The potential readings were recorded against time (Sec). The lifetime of the investigated Cu2+electrodes were measured from the response potential to the varying Cu2+concentration every day for more than 6 weeks. This electrode has been used as an indicator electrode in potentiometric titration of Cu2+ ion with EDTA and direct determination of Cu2+ ion in wastewater of the electroplating industry. The direct determination of copper ion in wastewater of the electroplating industry gave results that compare favorably with those obtained by the atomic absorption spectrophotometric method. The electrodes were successfully applied for the determination of copper ion. The Co2+-4-formylazohyrazoaniline antipyrine complex can be regarded as a carrier for the construction of a novel PVC-based membrane using DOP and DOS as plasticizers for cobalt detection. The proposed electrode has good operating characteristics (sensitivity, stability, response time, detection limit and a wide linear range). It is easy to prepare and use, this electrode has been used as an indicator electrode in potentiometric titration of Co2+ ion with EDTA and direct determination of Co2+ ion in real samples, the direct determination of cobalt ion in tap water and samples from local rive Nile gave results that compare favorably with those obtained by the atomic absorption spectrophotometric method. The electrodes were successfully applied for the determination of cobalt ion. |