الفهرس 
Trends in the cobalt(III) corrinoids absorption spectraOnly 14 pages are availabe for public view
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Abstract
The thesis content can be portrayed briefly as four chapters:
Chapter (I): General introduction:
- This chapter contains general introduction regarding the work done and includes three parts:
Part (I): It contains an overview about vitamin B12 and cobesters, in addition to literature survey about vitamin B12 derivatives.
Part (II): It illustrates the main principles and components of ISEs, the difficulties facing some types of ISEs, limitations of conventional and coated wire ISEs, and novel designs for potentiometric sensors.
Part (III): It illustrate the definition of nanomaterials. The description of ferrite nanoparticles and their synthesis methods, the surface modification of nanoparticles, in addition to adsorption and desorption techniques. And also it contains Literature survey regarding development of nanomaterials as adsorbent for waste water treatment.
Chapter (II): Novel spectrophotometric method hydrosulfide (HS-) ions assessment using Vitamin B12 precursor “Aquacyanocobyrinic acid heptamethyl ester”:
In this chapter, a simple spectrophotometric method with good selectivity and high sensitivity towards sulfide ions is introduced. The method is based on the replacement of the axial water molecule of the aquacyanocobyrinic acid heptamethyl ester (ACCbs) reagent after the reaction with HS- ions, and forming stable complex. ACCbs reagent is characterized with three distinguishable absorption bands with absorption maxima at 353, 497 and 527 nm. After adding HS-, a new absorption band at 582 nm has been obtained. The decrease of the absorption bands of the reaction product at 353, 497 and 527 nm and the enhancement of the band at 582 nm are quantitatively linear to HS- concentration over the concentration range 0.02-1.543 μg mL-1 with lower limit of detection 0.019 μg mL-1. No noticeable interferences are caused by most common ions. Suitability for the assessment of HS- in complex matrices without prior treatment was shown after validation of the method according to the standards of quality assurance. The method has the advantage of high stability of the reagent and reaction product and absorbance measurements at four different wavelengths in the same run. The method is successfully applied to monitor the hydrosulfide contents in water samples. The results compare fairly well with data obtained using the standard method.
Chapter (III): Solid contact potentiometric sensors for reliable automatic quantification of 2,4-dichlorophenol (2,4-DCP) as a food taint:
In this chapter, sensitive, selective and simple solid-contact potentiometric sensors were fabricated and characterized for 2,4-dichlorophenol (2,4-DCP) quantification. The membrane sensors based on the use of TDMAC and Aliquat 336 as anion exchangers, were distributed in plasticized PVC matrix. They revealed a super-Nernstian responses with a slopes -70.3 and -78.2 over linear range 5.8×10-6 - 5.0×10-3 M and 3.3×10-5 - 5.0×10-3 M with detection limits of 0.7 and 1.1 μg/mL for TDMAC and Aliquat 336, respectively. The sensors were compared with the conventional type sensors. Effect of plasticizer on the potentiometric response and diverse foreign common ions effects were examined. The sensors of both types showed long life span, good selectivity for (2,4-DCP) over a wide assortment of other common ions, long term stability, high reproducibility, and rapid response. Validation of method illustrates good performance characteristics of the recommended sensors by evaluation the lower detection limit, range, accuracy, precision, repeatability and between-day-variability. The sensors were effectively applied for persistent monitoring of (2,4-DCP) using flow injection system. The sensors were applied to the (2,4-DCP) potentiometric determination in spiked urine and fish samples. Recoveries ranged from 90.5 to 110%.
Chapter (IV): preparation and characterization of magnetic copper ferrite and copper ferrite thiophene nanoparticles for removal of Hg(II) ions as hazardous waste:
In this chapter, CuFe2O4 nanoparticles were synthesized by co-precipitation method and modified via wrapping the CuFe2O4 with thiophene for Hg(II) ions removal from aqua media. CuFe2O4 nanoparticles with and without thiophene were well-defined by X-Ray Diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray (EDX), High resolution transmission electron microscopy (HRTEM) and Brunaure-Emmet-Teller (BET). Contact time, adsorbent dose, solution pH, adsorption kinetics, adsorption isotherm and recyclability were studied. The maximum adsorption capacity was 7.53 and 208.8 mg g-1 for CuFe2O4 and CuFe2O4@polythiophene nanocomposite; respectively thus CuFe2O4@polythiophene nanocomposite is more favorable than CuFe2O4 for Hg(II) removal. The promising adsorption performance of Hg(II) ions by CuFe2O4@polythiophene nanocomposite generates from soft acid-soft base strong interaction of thiophene sulfur group with mercury(II) ions. Furthermore, CuFe2O4@polythiophene nanocomposite has high stability and reusability due to its removal efficiency has no significant decrease after five adsorption-desorption cycles and can be merely removed from aqua media by exterior magnetic field after adsorption experiments took place. So that, CuFe2O4@polythiophene nanocomposite is applicable for removal Hg(II) ions from aqueous solution and may be suitable for removal other heavy metals.