Zinc oxide (ZnO) nanoparticles were synthesized by chemical precipitation method using 0.1M and 0.3M [Zn(NO3)2.6H2O] and Na2CO3 solutions. The particle size and band gap of ZnO nanoparticles were estimated and effect of concentration on it was investigated. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and UV-visible spectroscopy. The XRD result revealed that synthesized ZnO nanoparticles have pure hexagonal wurtzite structure and the particle size varies from 27.0 nm to 29.9 nm estimated by using Debye-Scherrer’s equation. The TEM image also projected the average particle size in the range of 20-30 nm and selected area electron diffraction (SAED) further verified the formation of hexagonal wurtzite structure. The FTIR result showed a broad absorption band related to Zn-O vibration band. The UV-visible absorption showed a red shift in the absorption edge with increasing concentration of Zn(NO3)2.6H2O solution. The sizes and band gaps of ZnO nanoparticles increased and decreased, respectively with increasing concentration of Zn(NO3)2.6H2O solution from 0.1M to 0.3M.

Zirconia (ZrO2) nanoparticles are polymorphic materials having a wide range of applications. It can be synthesized via green as well as chemical synthesis methods. In this work, ZrO2 nanoparticles were synthesized by the green method using Curcuma longa extract. Curcuma longa extract was prepared using the standard method. The synthesized ZrO2 was characterized by the X-ray diffraction (XRD) analysis and Fourier transform infra-red (FTIR) spectroscopy for their structural and size analysis. The analysis of the XRD pattern of ZrO2 showed the tetragonal phase structure and the size was calculated using the Debye Scherrer equation which was about 34.55 nm. The FTIR spectra analysis showed a broad absorption peak particularly at about 774 cm-1 and about 499 cm-1 correspondings to Zr-O2-Zr asymmetric and Zr-O stretching modes, respectively. The characterized ZrO2 nanoparticles were used for the preparation of epoxy resin/ZrO2 nanocomposites. The compressive strength of pure epoxy resin and epoxy resin/ZrO2 nanocomposites were measured by a compressive strength tester and the result indicates the high amount of zirconia was not suitable for the nanocomposites.

Zirconia (ZrO2), an inorganic material, is a very fascinating material due to its high mechanical strength and fracture toughness. The synthesis is carried out by using co-precipitation method using optimum content of zirconium oxychloride octahydrate (ZrOCl2.8H2O) with NaOH solution at calcination temperature of 700°C. The synthesized samples were characterized to ensure structural, functional, morphological and chemical composition by several techniques. The monoclinic structure has been confirmed from XRD, SAED and Raman spectra. The Zr-O stretching vibration and Zr-O2-Zr bending vibrations were confirmed through FTIR analysis. The well dispersed particles with spherical morphology were established through SEM and TEM analyses. EDX spectra confirmed the formation of pure zirconium oxide. The band gap was calculated with the help of UV-Vis spectra and particle size was determined form XRD data using Debye Scherrer’s equation. The variation of band gap and particle size compared with different concentrations of precursor solution was studied. BIBECHANA 18 (2021) 1-9

A promising adsorbent, charred water hyacinth (CWH) for the removal of Ca(II) from the aqueous solution was explored by heat treatment of water hyacinth followed by chemical activation with acidified zinc chloride (ZnCl2). The adsorbent was characterized using scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) spectroscopy. Batch adsorption techniques were conducted for Ca(II) adsorption to assess the adsorption isotherm, effect of pH, contact time, initial Ca(II) concentration, adsorbent doses, and adsorption kinetics. The SEM micrograph illustrates the rough and irregular surface morphology and EDX spectra confirm the successful adsorption of Ca(II) on the adsorbent surface. The equilibrium adsorption data better fitted to the Freundlich isotherm model having a maximum adsorption capacity (qmax) of 319.75 mg/g. The highest percentage of adsorption was found at pH 1.5. The adsorption of Ca(II) by CWH decreased at the higher metal concentration and lower adsorbent doses. The adsorption of Ca(II) ions onto CWH followed the pseudo-second-order kinetics model. . Overall, these results suggested that the as-prepared CWH can be used as an eco-friendly, economical and efficient alternative for the removal of Ca(II)  from the aqueous solution.