الفهرس 
General introductionOnly 14 pages are availabe for public view
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Abstract
- The thesis content can be portrayed briefly as five chapters:
➢ Chapter (I): General introduction:
- This chapter contains a general introduction regarding the work done and includes two parts:
• Part (I): It contains an overview of electronic waste, the composition of e-waste, sources of e-waste, the Current processes for e-waste recycling and a general view about End-processing technologies and materials recovery.
• Part (II): It illustrates the main principles and components of ISEs, an overview about solid-contact ion-selective electrodes, the difficulties facing some types of ISEs, limitations of conventional and coated wire ISEs, and Challenges in potentiometric solid-contact ion-selective electrodes.
• Chapter (II): Lead Extraction from Spent Cathode Ray Tube by Mechanochemical Activation:
A mechanochemical activation technique to effectively extract lead from funnel glass of cathode ray tube (CRT) is proposed. More than 85.7% of lead can be extracted from the funnel glass powder in 5 M sodium hydroxide solution at 80°C after mechanochemical activation by ball milling with Ethylenediaminetetraacetic acid (EDTA). The chemical breakage in the glass inner structures will ease leaching of the activated Pb glass. The effects of time and temperature on the lead dissolution were investigated and a model was developed to depict the kinetic relationship. The leaching process was controlled by a mixed kinetic model. The activation energy was calculated and its value was 39.44 kJ/mol. The
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mechanochemical activation with EDTA for extracting lead from CRT funnel glass was found effective and promising process.
➢ Chapter (III): Potentiometric study for selective Determination of Thiocyanate in the Saliva and Urine of Cigarette Smokers using solid type PVC membrane sensor:
In this chapter, A solid type thiocyanate electrode based on Al (III) [4-(2-Pyridylazo) resorcinol] (Al/PAR) and Mg (II) phthalocyanine (MgPC) complexes as a charged carrier, aliquate 336S and TDMAC as ion exchangers in plasticized poly (vinyl chloride) membrane. These solid type electrodes exhibited significantly enhanced response towards SCN- ions over the concentration range 5.0x10-6-1.0x10-2 mol L-1 with a lower detection limit of 0.08-0.44 μg mL-1. The sensors displayed near-Nernstian slope of -53.7-55.8 mV decade-1 for SCN- ions. The proposed sensors by the fixed solution method (FSM) exhibited a good selectivity over different anions which differ significantly from the classical Hofmeister series. The sensors were used for the determination of SCN−ions in saliva and urine samples collected from some non-smokers and smokers donors. The results obtained from the proposed sensors were agreed with that obtained using the standard methods of thiocyanate and cyanide analysis.
➢ Chapter (IV): Paper Strip and Ceramic Platform Based Potentiometric Sensors with Polyaniline Solid Contact for Continuous Monitoring of chromium in Industrial Samples:
In this chapter, Screen-printed membrane sensors based on the use of paper and ceramic substrates are fabricated, characterized and used for
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rapid batch and continuous monitoring of chromium(VI) in some industrial products and wastewater samples. Strips of paper and ceramic platform (15 x 5 mm) are covered with a conductive carbon paint and polyaniline (PANI) film, to act as ion-to-electron transducer, followed by a DROP casting of plasticized PVC Rhodamine-B chromate membrane as a recognition sensing material. In a 5.0 x 10-3 mol L-1 Trizma buffer solution of pH ~ 8, the fabricated sensors exhibit near Nernstain response for Cr(VI) ion with slopes of -29.7 ± 0.5 and -28.6 ± 0.3 mV/decade-1, limit of detection 2.5x10-5 and 2.4x10-6 mol L-1 and linear concentration range 7.5x10-3 - 5.0x10-5 and 7.5x10-3 - 1.0x10-5 mol L-1, respectively. Both sensors exhibit fast and stable potentiometric response, excellent reproducibility and good selectivity with respect to a number of common foreign inorganic species. Impedance spectroscopy and chronopotentiometry data reveal a small resistance and a larger double layer capacitance due to the presence of the intermediate polyaniline (PANI) conductive layer. Furtheremore, formation of a water layer between the ion selective membrane and the underlying conductor polymer and between the conducting polymer and the conducting surface is greatly reduced. The developed disposable solid-contact potentiometric sensors offer the advantages of simple design, long term potential stability, flexibility, miniaturization ability, short conditioning time, and cost effective that enabling mass production, The sensors were successfully used for static and hydrodynamic measurements of Cr(VI) and Cr(III) in some leather tanning wastewater and nickel-chrome alloy samples. The results compare favorably with data obtained by atomic absorption spectrometry.
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➢ Chapter (V): Gold plate electrodes functionalized by multiwall carbon nanotubes film for potentiometric thallium (I) detection:
In this chapter, A Solid-contact potentiometric ion-selective electrodes (SC-ISEs) for thallium determination have been designed using multiwall carbon nanotubes (MWCNTs) as the ion-to-electron transducer. Dispersed MWCNTs were drop-casted over a gold plate electrode. Two different crown ethers were used in the sensing membrane for the recognition of thallium (I). Sensors are based on dibenzo-18-crown-6 (DB18C6) as a neutral carrier and NaTPB as an anionic additive , exhibited a near Nernstian response of 57.3 mV/decade towards Tl+ ions over the activity range 4.5x10-6- 7.0x10-4 M with a limit of detection 3.2 x10-7 M. The time required to achieve a 95 % of the steady equilibrium potential was <10 s. The complex formation constant (log βML) between dibenzo-18-crown-6 and thallium (I) (i.e. 5.99) was measured using the sandwich membrane technique. The potential response was pH independent over the range 3.0–9.5. The introduction of MWCNTs as an electron-ion-transducer layer between gold plate and the sensing membrane leads to a smaller membrane resistance and a large double layer capacitance, which has been proven using impedance spectra and chronopotentiometry (i.e. 114.9±12 kΩ, 52.1±3.3 pF and 200±13.2 kΩ, 50±4.2μF). Additionally, reduction of the water layer between the sensing membrane and the underlying conductor is tested. Thus, it is clear that MWCNTs, can be used as a transducing layer in SC-ISEs. The proposed sensor is introduced as an indicator electrode for potentiometric titration of single and ternary mixtures of I-, Br- and S2- anions