Abstract
The aim of this study was to synthetize new porous nanoparticles based on methyltrimethoxysilane coated hydroxyapatite (MTHAp) for lead removal form aqueous solutions. The morphological and compositional analysis of MTHAp were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Removal experiments of Pb2+ions were carried out in aqueous solutions with controlled concentration of Pb2+at a fixed pH value of 3 and 5 respectively. After the removal experiment of Pb2+ions from solutions, porous hydroxyapatite nanoparticles were transformed into PbMTHAp_3 and PbMTHAp_5 via the adsorption of Pb2+ions followed by a cation exchange reaction. The X-ray diffraction spectra of PbMTHAp_3 and PbMTHAp_5 revealed that the powders, after removal of the Pb2+ions, were a mixture of Ca2.5Pb7.5(PO4)6(OH)2, Pb2Ca4(PO4)2(SiO4), and Ca10(PO4)6(OH)2. Our results demonstrate that the porous hydroxyapatite nanoparticles can be used as an adsorbent for removing Pb2+ions from aqueous solutions.
Highlights
One of the major environmental problems is represented by the global contamination with potentially toxic trace elements (PTTE)
The morphological and compositional analysis of methyltrimethoxysilane coated hydroxyapatite powder before (MTHAp) were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS)
In previous studies realised by Karakassides et al [27] and Bogya et al [28] it was shown that the distortion is caused by the stretching vibrations assigned to the Si–O–Si bonds that should appear in the range of 950–1200 cm−1
Summary
One of the major environmental problems is represented by the global contamination with potentially toxic trace elements (PTTE). Lead has been widely used in the industrial field, for lead-based batteries, ammunition, paints, and building materials [1,2,3,4] Due to their nonbiodegradable behaviour and their incapacity of metabolization and decomposition, PTTE like Pb, Cu, Cd, Zn, and Hg are the main contaminants of soils and ground or surface waters. Because of its unique properties, such as resistance to corrosion, malleability, and poor conductibility, it has been used since ancient times for many applications being found in pipes, pottery, or pigments [5] Over time, it has become more and more clear that lead exposure for a long period of time may cause many health problems, affecting the human reproductive, nervous, gastrointestinal, immune, renal, cardiovascular, skeletal, muscular, and hematopoietic systems [5, 6].
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