Abstract
In the present work nano-hydroxyapatite/ Carboxymethyl Cellulose (n-HApCMC) composite was synthesized by precipitation method and was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) crystallography and scanning electron microscopy (SEM). The n-HApCMC composite was tested for the adsorption of Mercury from aqueous solution and compared its removal capacity with nano-hydroxyapatite (HAp). Effect of various physico-chemical parameters such as pH, adsorbent dose, contact time, initial metal ion concentration and temperature on adsorption of metal ions onto n-HApCMC composite was investigated. The adsorption process followed pseudo-second order kinetics and intra-particle diffusion model. Equilibrium data were fitted well in the Langmuir and Freundlich isotherm models. The thermodynamic analysis also established that the adsorption process was endothermic and spontaneous.
Highlights
Heavy metal pollution has become an environmental problem throughout the world because heavy metals can be accumulated into the food chain and cause serious problems, for ecosystems and for human health
In the X-ray diffraction (XRD) pattern of n-HAp, the crystalline peaks at 2θ= 25.9°, 31.9°, 32°, 34.5°and 40°confirm the formation of hydroxyapatite
This indicated that there was no marked change in the peak structure after the composite formation and confirms that the crystal structure of n-HAp is retained in n-HApCMC composites
Summary
Heavy metal pollution has become an environmental problem throughout the world because heavy metals can be accumulated into the food chain and cause serious problems, for ecosystems and for human health. The selective removal of industrial heavy metals from liquid waste is the subject of considerable ecological and economic interest [1]. Aromatic compounds (including phenolic derivatives, and polycyclic aromatic compounds) and dyes are often found in the environment as a result of their wide industrial uses. Wastes containing soluble toxic heavy metals require concentration of the metals into a smaller volume followed by recovery and secure disposal. Heavy metals can be removed by adsorption on solid matrices. The total Hg emissions from waste incineration are largely underestimated because of poor knowledge about Hg content in wastes and due to economic reasons there are no or only limited analyses available on Hg content in flue gases from a majority of the waste incineration plants in operation [10]
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