Two types of (Ca10(PO4)6(OH)2) hydroxyapatite (HAP) powders with high purity were obtained using ... more Two types of (Ca10(PO4)6(OH)2) hydroxyapatite (HAP) powders with high purity were obtained using two different synthesis methods – a wet chemical synthesis method such as precipitation from aqueous solution and a dry chemical method such as solid-state sintering. Both types of powders were characterized by X-ray diffraction, FT-IR analysis, scanning electron microscopy (SEM), and N2 sorption analysis. X-ray diffraction showed that both HAP powders contain hydroxyapatite as the only crystalline phase. Data from X-ray diffraction were confirmed by FT-IR spectra. SEM images showed that nanometric size hydroxyapatite (nano-HAP) was obtained by precipitation from aqueous solution and hydroxyapatite with micrometric size (micro-HAP) was obtained using sintering method as a solid phase synthesis method. Nano-HAP powder has a BET surface area almost 5 times higher than that of the microcrystalline HAP powder. Consequently, both powders were comparatively tested in lead removal process from aqueous solutions. The contact time, the concentration of lead ions in the initial solution, pH and temperature were the main parameters studied. The highest Pb(II) sorption was achieved for nano-HAP. The sorption process was relatively fast because the equilibrium was achieved after about 60-180 min of contact depending on the lead concentration in the initial solution, and the specific surface area of the samples. Results showed that the adsorption behaviour of micro-HAP and nano-HAP follows the Langmuir isotherm. The kinetic process of Pb(II) sorption onto micro-HAP and nano-HAP was tested by applying the pseudo-first order, the pseudo-second order, and intraparticle diffusion models. The experimental data were fitted with pseudo-second order equation. The main mechanism for lead ions removal using synthesized micro-HAP and nano-HAP was suggested to be dissolution of HAP followed by hydroxy-pyromorphite (Pb5(PO4)3OH) precipitation. From this experimental study, it can be concluded that both sorbents can be successfully applied for lead removal from wastewater.
In the present work, nano-hydroxyapatite (nano-HAP) prepared in microwave field was applied to re... more In the present work, nano-hydroxyapatite (nano-HAP) prepared in microwave field was applied to remove lead(II), nickel(II), zinc(II) and copper(II) from polycationic aqueous solutions. Optimum adsorption conditions were evaluated using batch experiments. Effect of various physicochemical parameters such as: pH, contact time, and initial ion concentration on adsorption of metal ions onto nano-HAP was evaluated. Batch experiments revealed that removal ration decreased in the order: 87.1% for Pb(II), 44.66% for Zn(II), 20.39% for Cu(II) and 19.97% for Ni(II) in mixed solutions with the initial solution with concentration 90.72 mg Pb(II)/L, 92.32 mg Zn(II)/L, 108.8 mg Cu(II)/L, and 99.39 mg Ni(II)/L. The maximum adsorption capacity of lead, nickel, zinc and copper determined were 79.02 mg/g, 19.85 mg/g, 41.23 mg/g and 22.18 mg/g. The results of this research study can lead to the conclusion that nano-hydroxyapatite can be used as a cost-effective material for the removal of lead, nickel, zinc and copper from polycationic aqueous solutions.and wastewater. The selectivity of this material follows the series: Pb(II) > Zn(II) > Cu(II) > Ni(II).
o-Vanillin functionalized mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41-N-oVan) was synt... more o-Vanillin functionalized mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N 2 adsorption–desorption technique and magnetic measurements. The capacity of Fe 3 O 4 @MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41) and amino – modified mesoporous silica coated magnetite (Fe 3 O 4 @MCM-41-NH 2). The effect of adsorption process parameters such us pH, contact time, initial Pb(II) concentration was also investigated. The adsorption data were successfully fitted with the Langmuir model, exhibiting a maximum adsorption capacity of 155.71 mg/g at pH¼4.4 and T¼ 298 K. The results revealed that the adsorption rate was very high at the beginning of the adsorption process, 80–90% of the total amount of Pb(II) being removed within the first 60 min, depending on the initial concentration. The results of the present work suggest that Fe 3 O 4 @MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water.
Nano-hydoxyapatite was prepared using a rapid microwave method as an effective sorbent for lead(I... more Nano-hydoxyapatite was prepared using a rapid microwave method as an effective sorbent for lead(II) and copper(II) removal from aqueous solutions. The surface of the produced nano-hydoxyapatite has a porous structure and the specific surface area according to the BET model in value of 88.75 mg/g. Batch experiments revealed that removal ration increased in the order of lead (96.56 %), and copper (40.69%) in mixed solutions with the initial solution with concentration 100 mg Cu(II)/L amd 100 mg Pb(II)/L. The maximum adsorption capacity of lead and copper determined were 99.94 mg/g and 40.04 mg/g. The results of this research study can lead to the conclusion that nano-hydroxyapatite can be used as a cost-effective material for the removal of lead and copper from binary aqueous solutions and wastewater.
Two types of (Ca10(PO4)6(OH)2) hydroxyapatite (HAP) powders with high purity were obtained using ... more Two types of (Ca10(PO4)6(OH)2) hydroxyapatite (HAP) powders with high purity were obtained using two different synthesis methods – a wet chemical synthesis method such as precipitation from aqueous solution and a dry chemical method such as solid-state sintering. Both types of powders were characterized by X-ray diffraction, FT-IR analysis, scanning electron microscopy (SEM), and N2 sorption analysis. X-ray diffraction showed that both HAP powders contain hydroxyapatite as the only crystalline phase. Data from X-ray diffraction were confirmed by FT-IR spectra. SEM images showed that nanometric size hydroxyapatite (nano-HAP) was obtained by precipitation from aqueous solution and hydroxyapatite with micrometric size (micro-HAP) was obtained using sintering method as a solid phase synthesis method. Nano-HAP powder has a BET surface area almost 5 times higher than that of the microcrystalline HAP powder. Consequently, both powders were comparatively tested in lead removal process from aqueous solutions. The contact time, the concentration of lead ions in the initial solution, pH and temperature were the main parameters studied. The highest Pb(II) sorption was achieved for nano-HAP. The sorption process was relatively fast because the equilibrium was achieved after about 60-180 min of contact depending on the lead concentration in the initial solution, and the specific surface area of the samples. Results showed that the adsorption behaviour of micro-HAP and nano-HAP follows the Langmuir isotherm. The kinetic process of Pb(II) sorption onto micro-HAP and nano-HAP was tested by applying the pseudo-first order, the pseudo-second order, and intraparticle diffusion models. The experimental data were fitted with pseudo-second order equation. The main mechanism for lead ions removal using synthesized micro-HAP and nano-HAP was suggested to be dissolution of HAP followed by hydroxy-pyromorphite (Pb5(PO4)3OH) precipitation. From this experimental study, it can be concluded that both sorbents can be successfully applied for lead removal from wastewater.
In the present work, nano-hydroxyapatite (nano-HAP) prepared in microwave field was applied to re... more In the present work, nano-hydroxyapatite (nano-HAP) prepared in microwave field was applied to remove lead(II), nickel(II), zinc(II) and copper(II) from polycationic aqueous solutions. Optimum adsorption conditions were evaluated using batch experiments. Effect of various physicochemical parameters such as: pH, contact time, and initial ion concentration on adsorption of metal ions onto nano-HAP was evaluated. Batch experiments revealed that removal ration decreased in the order: 87.1% for Pb(II), 44.66% for Zn(II), 20.39% for Cu(II) and 19.97% for Ni(II) in mixed solutions with the initial solution with concentration 90.72 mg Pb(II)/L, 92.32 mg Zn(II)/L, 108.8 mg Cu(II)/L, and 99.39 mg Ni(II)/L. The maximum adsorption capacity of lead, nickel, zinc and copper determined were 79.02 mg/g, 19.85 mg/g, 41.23 mg/g and 22.18 mg/g. The results of this research study can lead to the conclusion that nano-hydroxyapatite can be used as a cost-effective material for the removal of lead, nickel, zinc and copper from polycationic aqueous solutions.and wastewater. The selectivity of this material follows the series: Pb(II) > Zn(II) > Cu(II) > Ni(II).
o-Vanillin functionalized mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41-N-oVan) was synt... more o-Vanillin functionalized mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N 2 adsorption–desorption technique and magnetic measurements. The capacity of Fe 3 O 4 @MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41) and amino – modified mesoporous silica coated magnetite (Fe 3 O 4 @MCM-41-NH 2). The effect of adsorption process parameters such us pH, contact time, initial Pb(II) concentration was also investigated. The adsorption data were successfully fitted with the Langmuir model, exhibiting a maximum adsorption capacity of 155.71 mg/g at pH¼4.4 and T¼ 298 K. The results revealed that the adsorption rate was very high at the beginning of the adsorption process, 80–90% of the total amount of Pb(II) being removed within the first 60 min, depending on the initial concentration. The results of the present work suggest that Fe 3 O 4 @MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water.
Nano-hydoxyapatite was prepared using a rapid microwave method as an effective sorbent for lead(I... more Nano-hydoxyapatite was prepared using a rapid microwave method as an effective sorbent for lead(II) and copper(II) removal from aqueous solutions. The surface of the produced nano-hydoxyapatite has a porous structure and the specific surface area according to the BET model in value of 88.75 mg/g. Batch experiments revealed that removal ration increased in the order of lead (96.56 %), and copper (40.69%) in mixed solutions with the initial solution with concentration 100 mg Cu(II)/L amd 100 mg Pb(II)/L. The maximum adsorption capacity of lead and copper determined were 99.94 mg/g and 40.04 mg/g. The results of this research study can lead to the conclusion that nano-hydroxyapatite can be used as a cost-effective material for the removal of lead and copper from binary aqueous solutions and wastewater.
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Papers by Rodica Patescu
different synthesis methods – a wet chemical synthesis method such as precipitation from aqueous solution
and a dry chemical method such as solid-state sintering. Both types of powders were characterized by X-ray
diffraction, FT-IR analysis, scanning electron microscopy (SEM), and N2 sorption analysis. X-ray diffraction
showed that both HAP powders contain hydroxyapatite as the only crystalline phase. Data from X-ray
diffraction were confirmed by FT-IR spectra. SEM images showed that nanometric size hydroxyapatite
(nano-HAP) was obtained by precipitation from aqueous solution and hydroxyapatite with micrometric size
(micro-HAP) was obtained using sintering method as a solid phase synthesis method. Nano-HAP powder
has a BET surface area almost 5 times higher than that of the microcrystalline HAP powder. Consequently,
both powders were comparatively tested in lead removal process from aqueous solutions. The contact time,
the concentration of lead ions in the initial solution, pH and temperature were the main parameters studied.
The highest Pb(II) sorption was achieved for nano-HAP. The sorption process was relatively fast because the
equilibrium was achieved after about 60-180 min of contact depending on the lead concentration in the
initial solution, and the specific surface area of the samples. Results showed that the adsorption behaviour
of micro-HAP and nano-HAP follows the Langmuir isotherm. The kinetic process of Pb(II) sorption onto
micro-HAP and nano-HAP was tested by applying the pseudo-first order, the pseudo-second order, and
intraparticle diffusion models. The experimental data were fitted with pseudo-second order equation. The
main mechanism for lead ions removal using synthesized micro-HAP and nano-HAP was suggested to be
dissolution of HAP followed by hydroxy-pyromorphite (Pb5(PO4)3OH) precipitation. From this experimental
study, it can be concluded that both sorbents can be successfully applied for lead removal from wastewater.
different synthesis methods – a wet chemical synthesis method such as precipitation from aqueous solution
and a dry chemical method such as solid-state sintering. Both types of powders were characterized by X-ray
diffraction, FT-IR analysis, scanning electron microscopy (SEM), and N2 sorption analysis. X-ray diffraction
showed that both HAP powders contain hydroxyapatite as the only crystalline phase. Data from X-ray
diffraction were confirmed by FT-IR spectra. SEM images showed that nanometric size hydroxyapatite
(nano-HAP) was obtained by precipitation from aqueous solution and hydroxyapatite with micrometric size
(micro-HAP) was obtained using sintering method as a solid phase synthesis method. Nano-HAP powder
has a BET surface area almost 5 times higher than that of the microcrystalline HAP powder. Consequently,
both powders were comparatively tested in lead removal process from aqueous solutions. The contact time,
the concentration of lead ions in the initial solution, pH and temperature were the main parameters studied.
The highest Pb(II) sorption was achieved for nano-HAP. The sorption process was relatively fast because the
equilibrium was achieved after about 60-180 min of contact depending on the lead concentration in the
initial solution, and the specific surface area of the samples. Results showed that the adsorption behaviour
of micro-HAP and nano-HAP follows the Langmuir isotherm. The kinetic process of Pb(II) sorption onto
micro-HAP and nano-HAP was tested by applying the pseudo-first order, the pseudo-second order, and
intraparticle diffusion models. The experimental data were fitted with pseudo-second order equation. The
main mechanism for lead ions removal using synthesized micro-HAP and nano-HAP was suggested to be
dissolution of HAP followed by hydroxy-pyromorphite (Pb5(PO4)3OH) precipitation. From this experimental
study, it can be concluded that both sorbents can be successfully applied for lead removal from wastewater.