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Fly ashHeavy metals Leaching Leachate Slag a b s t r a c t Fly ash and slag leachate pollution can be of great environmental concern due to generation of these wastes in huge quantities from their respective industrial units, mainly coalbased thermal power plants and iron and steel plants. For simulation of natural leaching in laboratory, various leaching methods are available, but selection of a method that can exactly simulate the real-life scenario for accurate estimation of various pollutants is challenging; particularly, the heavy metals present and impact due to reuse or disposal of these wastes. For choosing the most suitable leaching method according to specific situation, one must primarily consider the chemical and physical properties of wastes, the composition of the source, age of waste disposal, and the climatic conditions of the disposal area. Since these factors may not be specified, a variety of leaching methods with relevant equipment have been proposed by researchers; that are based on their required information to particular conditions in absence of a prescribed protocol and non standardization of equipment. The present review is an attempt to investigate the suitable leaching method for coal fly ash and slag.

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Gd 2 O 3 :Yb 3+ phosphor has been synthesized by the solid state reaction method with boric acid used as a flux. The resulting Gd 2 O 3 :Yb 3+ phosphor was characterized by X-ray diffraction (XRD) technique, Fourier transmission infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM), and photoluminescence and thermoluminescence. The results of the XRD show that obtained Gd 2 O 3 :Yb 3+ phosphor has a cubic structure. The average crystallite sizes could be calculated as 42.9 nm, confirmed by the TEM results. The study suggested that Yb 3+ doped phosphors are potential luminescence material for IR laser diode pumping.

Nanostructures, crystalline Zinc oxide powder were synthesized by mixing Zinc chloride (0.04M) and sodium hydroxide (0.08M) using chemical route method. 0.001M molar concentrations of TEA (Tri ethanolamine) in aqueous solution used to the growing reaction solution. The powder samples are annealed at 190 C. The experimental results indicate a successful growth of Zinc oxide in solid form which is not observed ever before. XRD, SEM, TEM and PL were performed to characterize the morphology, growth and optical nature of the samples. The some Rod and particle like morphology of zinc oxide has been examined by transmission electron microscopy. The particle size was found to vary from 7 to 21 nm. The room temperature PL spectra exhibits low intensity UV emission peak at 407 nm and blue emission band around 484 nm.

PhotoluminescenceScanning electron microscope CIE a b s t r a c tThe ZrO 2 phosphor doped with Eu 3þ was synthesized by solid state reaction method which is suitable for large scale production, and high temperature synthesis method.The prepared nanoparticles of ZrO 2 phosphor was characterized by X-ray diffraction technique (XRD) for Structural analysis and field emission gun scanning electron microscopy (FEGSEM)) for morphological details. The optical behavior of the prepared phosphor was determined by photoluminescence (PL) spectra recorded in room temperature. The PL excitation spectra was found at 311 nm range and the emission spectra in the range of 400e650 nm.

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