The Schiff bases (L 1-4 ) were prepared according previously reported procedure (Ramadan et al., 2018). The solutions of 4'-Aminoacetophenone or 3'-Aminoacetophenone and different benzaldehydes derivatives were separately prepared in absolute ethanol. The solutions were mixed with molar ratio 1:1 and the obtained mixtures were refluxed for 30 min. at 80 °C. The Schiff bases were precipitated out on cooling to room temperature and then filtered off. The precipitates were recrystallized from hot ethanol and left to dry under vacuum.

A new designed fluorescent chemosensor TYMN ((E)-1-((thiazol-2-ylimino)methyl) naphthalen-2-ol) for highly sensitive and selective tracing of trace amount of Zn 2+ ions in some real samples was synthesized and characterized. The sensor TYMN can detect Zn 2+ ions via fluorescence enhancement with a high selectivity over a wide range of metal ions, especially Cd 2+. The sensor showed large fluorescence enhancement upon complexation with Zn 2+ and simultaneous color change from yellow to orange. The limit of detection was analyzed to be 0.0311 μM with a linear dynamic range 0.1-1.0 μM. The sensor could work in a pH span of 5.0-8.0. Based on the physicochemical and analytical methods like electrospray ionization (ESI)-mass, Job plot, 1 H nuclear magnetic resonance (NMR) and theoretical calculations, the detection mechanism for Zn 2+ was explained based on restriction of internal charge transfer (ICT) mechanism. TYMN sensor was potentially utilized for Zn 2+ ions concentration evaluation in some real samples. Fluorescence microscopy experiments revealed that probe TYMN may have application as a fluorophore to detect the Zn 2+ in living cells.

KEYWORDSThis paper describes the versatile nature of clay that was obtained from Suez Gulf, Suez city, Egypt, as a new low cost natural resource which is non toxic to ecosystem and highly effective adsorbent material. The properties of the natural clay and its significance in removing Th(IV) and Ce(IV) as a representative of tetravalent actinides and lanthanides, respectively, La(III) as a representative of trivalent lanthanides as well as homologues of americium and Sr(II) as one of the fission products, in aqueous solutions have been studied, in order to consider its application for nuclear waste treatment. Batch experiments have been carried out to determine the effect of various factors such as initial metal ion concentration, clay dose, pH, contact time, and temperature on the adsorption process. The results have dictated that, the adsorption efficiency of the natural clay was significantly high at pH = 4. Maximum metal ion uptake capacity of clay has been obtained from batch studies was 99.24, 98.21, 77.76 and 57.94% for Th(IV), Ce(IV), La(III) and Sr(II), respectively. The thermodynamic parameters (H o , S o and G o ) have been calculated from the temperature dependent adsorption isotherms. Furthermore, separation factors () have been calculated in order to separate these elements from each other at pH = 4. Adsorption Natural clay Separation factor Radioactive waste Batch experiments Thermodynamic parameters