Tetraethyl Orthosilicate Coated Hydroxyapatite Powders for Lead Ions Removal from Aqueous Solutions (original) (raw)
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2016
This study aimed to investigate the effect of preparation conditions on different hydroxyapatite nanopowders (n-HAP), obtained on the laboratory scale, by the solution-precipitation and sol-gel methods, and to correlate the main characteristics like crystallinity and specific surface area with the ion Pb 2+ immobilization capacity. It is tested the increasing performance of nano-HAP so obtained, to remove heavy metals from aqueous solutions through dispersant addition (0.1…1.5%) and isomorphic substitution (Six-HAP, x=0.5; 1). Batch experiments were carried out using different synthetic nano-hydroxyapatites; powders were comparatively tested for lead removal process from aqueous solutions, under different conditions, i.e. initial metal ion concentration, and pH of the solutions. Results showed that all HAP powders obtained by precipitation contain hydroxyapatite as the only crystalline phase instead, the sol-gel HAP powders contains minor quantities of β-TCP. Experimental results sh...
Journal of Nanomaterials, 2014
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...
2013
Natural or synthetic hydroxyapatite [Ca10(PO4)6(OH)2] has a high exchange capacity for divalent heavy metal ions and is used to treat wastewater containing such ions. The reaction mechanism of hydroxyapatite with lead salts is carried out by dissolution followed by precipitation pyromorphite. As-synthesized HAp granules were analyzed by X-ray diffraction and FTIR spectroscopy. For the study of retention of lead ions were added Ca-hydroxyapatite granules in a solution of lead nitrate. By treatment with a solution of lead nitrate in all cases the chemical reaction leading to the formation pyromorphite, which is a positive result, as it is a compound of the less soluble lead. Hidroxiapatita naturală sau sintetică [Ca10(PO4)6(OH)2] are o mare capacitate de schimb pentru ionii divalenţi ai metalelor grele si se foloseste pentru tratarea apelor uzate care conţin astfel de ioni. Mecanismul de reacţie a hidroxiapatitei cu sărurile de plumb are loc prin dizolvarea acesteia urmată de precipit...
Adsorption Science & Technology, 2006
A porous hydroxyapatite (p-HAp) was prepared and employed for the removal of lead(II) ions at different concentrations from aqueous solution to determine the adsorption properties of p-HAp and compare them with those of a commercial hydroxyapatite (CAp) sample. The kinetic data obtained indicated that the adsorption performances of the adsorbents depended both on their specific surface area and crystallinity. Complexation of the Pb(II) ion on the adsorbent surface favoured the dissolution of hydroxyapatites characterized by a Ca/Pb molar ratio in the 0.85-1.5 range. The maximum adsorption capacity of p-Hap for Pb(II) ions at 30 ± 2 o C was 2.30 mmol/g relative to 1.38 mmol/g for the commercial compound Cap at the same temperature. The higher capacity of p-HAp was explained in terms of its porosity and crystallinity. The Pb(II) ions sorption results could be modelled by the Langmuir and Freundlich isotherms.
Adsorption of Pb (II) Ions onto Hydroxyapatite Nanopowders in Aqueous Solutions
Materials, 2018
Contamination of water with heavy metals such as lead is a major worldwide problem because they affect the physiological functions of living organisms, cause cancer, and damage the immune system. Hydroxyapatite, (Ca5(PO4)3OH) is considered one of the most effective materials for removing heavy metals from contaminated water. The hydroxyapatite nanopowders (N-HAp) obtained by a co-precipitation method were used in this research to determine the effectiveness in removing lead ions from contaminated solutions. In this study, we have investigated the structure and morphology of N-HAp nanopowders using X-ray diffraction (XRD), electronic transmission microscopy (TEM), and scanning electron microscopy (SEM). The structure information was also obtained by spectroscopy measurements. The Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy measurements revealed the presence of peaks corresponding to the phosphate and hydroxyl groups. The ability of N-HAp nanopowders to adsor...
African Journal of Pure and Applied Chemistry, 2011
The potential of the synthesized nano hydroxyapatite to remove Pb (II) from aqueous solutions was investigated in batch reactor under different experimental conditions. The study also investigates the effects of process parameters such as initial concentration of Pb (II) ion, temperature and adsorbent mass. Various thermodynamic parameters, such as G°, H° and S° have been calculated. The thermodynamics of Pb (II) ion onto nano HAp system indicates spontaneous and endothermic nature of the process. Lead uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich (DKR) model. The adsorption data follow the Langmuir model better than the Freundlich and DKR model and the adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 714.286 mg/g of Pb (II) ions on nano HAp.
Removal of lead ions using hydroxyapatite nano-material prepared from phosphogypsum waste
Nano-material of calcium hydroxyapatite (n-CaHAp), with particle size ranged from 50-57 nm which prepared from phosphogypsum waste (PG), was used for the removal of lead ions (Pb (II)) from aqueous solutions. It was investigated in batch reactor under different experimental conditions. The effects of process parameters such as pH, initial Pb ion concentration and adsorbent dose were studied. Also, various kinetic modeling had been studied where lead uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) model. The Pb ions adsorption onto n-CaHAP could best fit Langmuir isotherm model. The maximum adsorption capacity (qmax) for Pb ions was 769.23 mg/g onto n-CaHAp particles.
Polymers, 2021
In the present study, a new low-cost bioceramic nanocomposite based on porous hydroxyapatite (HAp) and cetyl trimethyl ammonium bromide (CTAB) as surfactant was successfully obtained by a simple chemical co-precipitation. The composition and structure of the HAp-CTAB were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer, and N2 adsorption/desorption analysis. The capacity of HAp-CTAB nanocomposites to remove the lead ions from aqueous solutions was studied by adsorption batch experiments and proved by Langmuir and Freundlich models. The Pb2+ removal efficiency of HAp-CTAB biocomposite was also confirmed by non-destructive ultrasound studies. The cytotoxicity assays showed that the HAp-CTAB nanocomposites did not induce any significant morphological changes of HeLa cells after 24 h of incubation or other toxic ...
International Journal of Biological Macromolecules, 2018
This research study shows the adsorptive potential of biopolymer based nanocomposite for the removal of Pb (II) ions from aqueous phase. The nanocomposite was synthesized by Femur calcined hydroxyapatite and Glutaraldehyde cross-linked chitosan. Characterizations like Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were performed to investigate the structural modifications, mineral composition and the surface texture of prepared nanocomposite. The adsorption of Pb(II) ions over nanocomposite reveals that the synthesized solid sorbent has promising abatement tendency for heavy metal ions. The adsorption process followed the pseudo-second-order kinetics and the equilibrium data of lead ions adsorption was best fitted to Sips isotherm model. The uptake capacity of synthesized nanocomposite increased from 209 mg/g to 354 mg/g with rise in temperature from 18 o C to 48 o C. The thermodynamic analysis suggested that the Pb(II) ions adsorption was spontaneous and endothermic in nature. Additionally, enthalpy of adsorption (~22.07 KJ/mol) indicated that the heavy metal ions were chemisorbed over nanocomposite surface. Adsorption of Pb 2+ increased about ~1.6 times in the observed pH range and highest uptake was obtained at pH 5.
Removal of aqueous lead ions by hydroxyapatites: Equilibria and kinetic processes
Journal of Hazardous Materials, 2007
The capacity of hydroxyapatite (HAp) to remove lead from aqueous solution was investigated under different conditions, namely initial metal ion concentration and reaction time. The sorption of lead from solutions containing initial concentrations from 0 to 8000 mg/L was studied for three different HAp powders. Soluble Pb and Ca monitoring during the experiment allows characterizing the mechanism of lead uptake. Dissolution of calcium is followed by the formation of a solid solution, Pb x Ca 10−x (PO 4) 6 (OH) 2 , with a Ca/P ratio decreasing continuously. Langmuir-Freundlich classical adsorption isotherms modeled adsorption data. The adsorption capacities calculated from this equation vary from 330 to 450 mg Pb/g HAp for the different solids. Modeling of the sorption process allows to determine theoretical saturation times and residual lead concentrations at equilibrium.