Abstract
Calcium Oxide (CaO) nanoparticles have been synthesized from waste eggshells (ES) as a source of calcium by solution combustion technique using muffle furnace and microwave oven. CaO nanoparticles obtained using muffle furnace (CaO-F) and via microwave oven (CaO-M) were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, AC conductivity and dielectric studies to correlate the physico-chemical behavior. The frequency dependence of AC conductivity, the permittivity (ε′) and dielectric loss tangent (D) studies have been undertaken in the frequency range 50 Hz–5 MHz at room temperature. AC conductivity was found to enhance with an increase in the frequency. The ε′ was found to decrease initially with the frequency and finally reaching a constant value at higher frequencies. The frequency dependence of D was found to exhibit a resonance peak in the studied frequency region. Catalytic activity of CaO-M was correlated with its dielectric behavior.
Highlights
Eggshell (ES) waste, is listed among the top 10 waste obtained from food processing industry
The average crystallite size of the Calcium oxide (CaO) particles were determined by the Debye-Scherrer formula, D = βCkoλsθ, where D is the crystallite size, k = 0.9 is a correction factor to account for the particle shapes, β is the full width at a half maximum of the most intense diffraction peak (200) plane, λ is the wavelength of a Cu Kα radiation (1.5406 Å) and θ is the Bragg angle
Lower particle size of CaO-M indicates that the CaO-M particles possesses large surface to volume ratio than that of the CaO nanoparticles obtained using muffle furnace (CaO-F) sample
Summary
Eggshell (ES) waste, is listed among the top 10 waste obtained from food processing industry. Disposal of ES is creating a huge problem due to difficulty associated with land fillings. It is economical in transforming waste biomaterial into material of commercial importance. Calcium oxide (CaO) is an important industrial compound, which finds a huge application as catalyst for heterogeneous base catalysed reactions, as C O2 adsorbent, as a calcium supplement. With time, huge waste eggshells bio-material is accumulated. It may lead to environmental harms, if ES are not disposed properly. Thereby it is striking the company holders in solving the problem of getting rid of the waste generated. Obtained CaO is used as a catalyst towards biodiesel manufacture [4, 5]
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