Nevenka Rajic | University of Belgrade (original) (raw)
Papers by Nevenka Rajic
Catalysts, 2020
Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety... more Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety of applications. We report on the photocatalytic activity of a readily available and inexpensive natural zeolite clinoptilolite (Z) containing SnO2 (Sn-Z). The Sn-Z samples with 3–15 wt. % of Sn were prepared by using a precipitation–deposition method. Powder X-ray diffraction analysis showed that the zeolite structure was unaffected by the introduction of the Sn-phase. Diffuse reflectance UV/VIS spectra of the Sn-Z samples confirmed the presence of SnO2 and X-Ray absorption spectroscopy analyses suggested that the SnO2 particles mainly resided on the surface of the clinoptilolite, while ATR-FTIR analysis gave some clues that part of the SnO2 phase was incorporated in the pores of the zeolite. The presence of SnO2 in Sn-Z increased both adsorption capacity and photocatalytic performance which could be partially explained by higher surface area and partially with an increased negative po...
Archives of Industrial Hygiene and Toxicology, 2020
Due to the development of resistance to antimicrobial agents, bacterium Acinetobacter baumannii i... more Due to the development of resistance to antimicrobial agents, bacterium Acinetobacter baumannii is nowadays a leading cause of nosocomial outbreaks. Clinically relevant A. baumannii outside hospital settings including natural soils affected by human waste represents a public-health risk for humans and animals. The aim of this study was to investigate the potential of metal-loaded zeolites to eliminate viable A. baumannii from artificially contaminated natural soils. A. baumannii isolate was subjected to the activity of natural zeolitised tuff (NZ) and Cu-modified (CuNZ) or Ag-modified zeolite (AgNZ) in wet, slightly acidic terra rossa and slightly alkaline red palaeosol. A. baumannii survived in terra rossa and red palaeosol supplemented with 1 wt% of NZ for seven days and four months, respectively. The addition of 1 wt% of CuNZ to terra rossa and red palaeosol shortened the survival of A. baumannii to three and 14 days, respectively. The addition of 0.1 wt% of AgNZ to both soils re...
Water Air and Soil Pollution, Dec 6, 2013
A macroporous, hydrophobically modified poly(acrylic acid-acrylamide) hydrogel was prepared. The ... more A macroporous, hydrophobically modified poly(acrylic acid-acrylamide) hydrogel was prepared. The fourier transform infrared (FTIR) spectrum and field emission scanning electron microscopy (FE-SEM) results showed that the hydrogel had a macroporous structure. The dynamic swelling and removal of cationic dyes, crystal violet (CV) and basic magenta (BM), by this macroporous hydrophobically modified poly(acrylic acidacrylamide) hydrogel were studied. The adsorption capacity and kinetic and isotherm studies of the cationic dyes into the hydrogels have been evaluated. It was found that the macroporous hydrophobically modified hydrogel (M) exhibited improved swelling and adsorption capacity compared with the non-macroporous hydrophobically modified hydrogel (NM). The adsorption process agreed very well with the Langmuir model and the adsorption of the cationic dyes depended on the pH of the solution via a mechanism combining swelling, electrostatic, and hydrophobic interactions. Moreover, adsorption kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model, indicating that chemical adsorption was the rate-limiting step.
Minerals, 2021
The adsorption of the antibiotic ciprofloxacin (CIP) from an aqueous solution by natural zeolite,... more The adsorption of the antibiotic ciprofloxacin (CIP) from an aqueous solution by natural zeolite, the calcium-rich clinoptilolite (CLI), and magnetite-coated CLI (MAG-CLI) was investigated. Both CLI and MAG-CLI showed a high adsorption affinity towards CIP at 283, 288 and 293 K at a pH of 5. Adsorption kinetics studied for the initial concentrations of 15–75 mg CIP dm−3 follow Lagergren’s pseudo-second order equation and the adsorption is best represented by the Langmuir model. The adsorption mechanism involves strong electrostatic interactions between negatively charged aluminosilicate lattice and the cationic form of CIP accompanied by an ion-exchange reaction. Magnetite coverage (approx. 12 wt.%) induces magnetism, which can facilitate the separation process. The coverage does not influence the adsorption activity of CLI. The leaching test showed that the MAG coating protects the adsorbent from CIP leaching. This is ascribed to interactions between the CIP carboxyl groups and mag...
Microporous and Mesoporous Materials, May 1, 2016
In this study the uptake capacity of Mn(II) ions by zeolite A beads was investigated for differen... more In this study the uptake capacity of Mn(II) ions by zeolite A beads was investigated for different initial Mn concentration (100-400 mg Mn dm-3) in batch mode at 25-55 ºC. The obtained adsorption capacity varying from 30 to 50 mg Mn g-1 demonstrated a high affinity of zeolite A towards Mn(II) present in solutions. Kinetic studies indicated the intra-particle diffusion as the rate limiting step up to 45 °C with apparent diffusivities in the range (1.2-2.0)×10-13 m 2 s-1 and the activation energy of 21.9 kJ mol-1 , which implies strong interactions between the zeolite A and Mn ions. At 55 °C ion-exchange became the rate limiting step. The adsorption isotherms were studied at 25 o C showing that the Mn adsorption is the best described by the Langmuir model suggesting a homogenous zeolite surface. XPS analysis of the Mn-loaded beads showed that there is no surface accumulation of Mn but an almost uniform Mn distribution inside zeolite A, whereas XANES and EXAFS suggested that the adsorption of Mn(II) was followed by the Mn(II) oxidation and oxide formation. Regeneration of the spent zeolite was examined in 8 adsorption/desorption cycles by a chelating Na 2 EDTA in a fluidized column. It has been found that zeolite A beads could be reused for at least 4 cycles with satisfactory Mn(II) adsorption efficiencies of about 70 %.
Book of abstracts, Jun 23, 2013
Catalysts, Feb 19, 2020
Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety... more Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety of applications. We report on the photocatalytic activity of a readily available and inexpensive natural zeolite clinoptilolite (Z) containing SnO 2 (Sn-Z). The Sn-Z samples with 3-15 wt. % of Sn were prepared by using a precipitation-deposition method. Powder X-ray diffraction analysis showed that the zeolite structure was unaffected by the introduction of the Sn-phase. Diffuse reflectance UV/VIS spectra of the Sn-Z samples confirmed the presence of SnO 2 and X-Ray absorption spectroscopy analyses suggested that the SnO 2 particles mainly resided on the surface of the clinoptilolite, while ATR-FTIR analysis gave some clues that part of the SnO 2 phase was incorporated in the pores of the zeolite. The presence of SnO 2 in Sn-Z increased both adsorption capacity and photocatalytic performance which could be partially explained by higher surface area and partially with an increased negative potential of the surface. Adsorption and total degradation of methylene blue (MB) for the Sn-Z with the highest amount of Sn (15 wt.%) was about 30% and 45%, respectively, suggesting a synergetic effect between SnO 2 and the clinoptilolite lattice. Reusability tests showed that these catalysts present a promising material for water purification.
Food Technology and Biotechnology
Research background. In the recent years, considerable attention has been given to selenium statu... more Research background. In the recent years, considerable attention has been given to selenium status since its deficiency is linked with various disorders and affects at least 13 % of world population. Additionally, mushrooms are known to possess pronounced capacity for absorption of various micronutrients, including Se, from soil/substrate. Here, we investigate the possibility of using Se-rich zeolitic tuff as a supplement for production of selenized mushroom. Furthermore, the impact of the enrichment on the activity of antioxidant enzymes and biological potential of Coriolus versicolor medicinal mushroom is studied. Experimental approach. Se(IV)- and Se(VI)-modified natural zeolitic tuff from the Serbian deposit Zlatokop was used as supplement for mushroom cultivation. To examine the effectiveness of selenium enrichment, we determined total selenium with inductively coupled plasma mass spectrometry (ICP-MS), together with the activity of antioxidant enzymes in fresh fruiting bodies ...
Catalysts, 2022
The present study focuses on clinoptilolite (CLI)-rich natural zeolitic tuffs and their photocata... more The present study focuses on clinoptilolite (CLI)-rich natural zeolitic tuffs and their photocatalytic activity in the degradation of cationic organic dyes. CLI from different regions was tested in the photocatalytic degradation of methylene blue (MB) as a model cationic dye. The photocatalytic tests were performed at room temperature and atmospheric pressure under visible light irradiation. For all the CLI samples, the highest activity was observed at pH = 6. Total MB degradation varied between 70 and 91% (C0 = 10 mg dm–3, 0.2 g dm–3 of photocatalyst, during 300 min). It is suggested that the presence of Fe species in the studied tuffs is responsible for the photocatalytic activity. The activity increases linearly with the Fe content in the tuffs. The MB photodegradation follows the Langmuir–Hinshelwood kinetic model. The recyclability tests showed good stability and efficiency of the photocatalyst. The degradation rate decreased from 91 to 69% during three reaction cycles, indicat...
Croatica Chemica Acta, 1999
Diffuse-reflectance spectroscopy (DRS), X-ray absorption near-edge structure (XANES) and extended... more Diffuse-reflectance spectroscopy (DRS), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) methods are applied to an investigation of Mn, Co and Ni local environments in MnAlPO, CoAlPO, and NiAlPO materials with chabazite-like topology. For all three products, insertion of the transition metals into tetrahedral Al-sites has been found. Calcination and rehydration of the as-synthesised materials cause a change of the oxidation number and co-ordination geometry of Mn and Co, while the oxidation and co-ordination number of Ni remain unaffected.
Minerals, Jun 29, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Desalination and Water Treatment, Oct 7, 2015
AbstractSorption of the Zn2+ and Ni2+ ions by the Na+-enriched natural clinoptilolite (Na-CLI) fr... more AbstractSorption of the Zn2+ and Ni2+ ions by the Na+-enriched natural clinoptilolite (Na-CLI) from aqueous solutions containing both Zn2+ and Ni2+ ions at a range of concentrations has been studied at 298, 308, and 318 K. It was found that the sorption of a particular ion by Na-CLI increases with the increase in the initial concentration of the solution of that ion. At a given initial concentration, the sorption degree increases with temperature. Also, the sorption of a particular ion is greater when the initial solution contains a second ion than it is when the particular ion is present alone. The sorption kinetics is in accord with the pseudo-second-order reaction rate model. The values of the k2 rate constant do not show a regular change with the initial Zn2+/Ni2+ concentrations probably because the presence of the second ion has a significant effect on the reaction rate. Thermodynamic study has shown that the sorption is exothermic, occurring spontaneously in the 298–318 K range and with a positive e...
ChemInform, Aug 23, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Elsevier eBooks, 2008
The thermal degradation of cetyltrimethylammonium bromide (CTMAB) inside the mesoporous SBA-3 was... more The thermal degradation of cetyltrimethylammonium bromide (CTMAB) inside the mesoporous SBA-3 was studied under non-isothermal conditions. There are two distinct and complex kinetic processes which partly overlap, each consisting of one dominant and three minor individual processes. The two dominant processes can be described by the Sestak-Berggren model. The main decomposition step (the first dominant process) involves the overcoming of weak interactions between CTMAB and the silica network and proceeds with a lower E a value (116±2 kJ mol-1) than the second dominant process (153±5 kJ mol-1), which can be explained by the size reduction of the pore openings due to the contraction of the SBA-3 unit cell caused by the removal of CTMAB.
Minerals, May 14, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
![Research paper thumbnail of The true symmetry of [H<sub>3</sub>NCH<sub>2</sub>CH<sub>2</sub>NH<sub>3</sub>]<sub>2</sub>[FeO(PO<sub>4</sub>)<sub>4</sub>].H<sub>2</sub>O with an open-framework structure](https://attachments.academia-assets.com/107255250/thumbnails/1.jpg)
](Acta Crystallographica Section A, Aug 25, 2000
ECM Nancy s387 conference abstracts o.m3.p1 The true symmetry of [H 3 NCH 2 CH 2 NH 3 ] 2 [FeO(PO... more ECM Nancy s387 conference abstracts o.m3.p1 The true symmetry of [H 3 NCH 2 CH 2 NH 3 ] 2 [FeO(PO 4) 4 ] ⋅ H 2 O with an open-framework structure.
Australian Journal of Chemistry, 1991
The SAPO, MeAPO and MeSAPO microporous materials (Me=co2+ and/or 2n2+) having a sodalite structur... more The SAPO, MeAPO and MeSAPO microporous materials (Me=co2+ and/or 2n2+) having a sodalite structure have been obtained hydrothermally at 200°C in the presence of tetramethylammonium ion as the template. The SAPO and MeSAPO products prepared at lower template concentrations are formed through a partial replacement of both aluminium and phosphorus by silicon in the parent aluminophosphate lattice; at higher pH only phosphorus is replaced. While the ~e~+ ions are in all cases constituents of the framework, most zinc-containing materials have a fraction of the zn2+ ions located in the cavities. T.g.a. shows that complete removal of the trapped organic component can not be easily accomplished. This can be explained by the small size of the openings in the sodalite cages. Powder diffraction analysis shows that replacement of aluminium by silicon, cobalt and zinc, and phosphorus by silicon leads to an expansion of the parent aluminophosphate unit cell. Kinetic studies suggest that crystallization of the silicon-containing products is preceded by an induction period of about 2 h, the nucleation taking place both in the liquid and solid phase.
Catalysts, 2020
Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety... more Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety of applications. We report on the photocatalytic activity of a readily available and inexpensive natural zeolite clinoptilolite (Z) containing SnO2 (Sn-Z). The Sn-Z samples with 3–15 wt. % of Sn were prepared by using a precipitation–deposition method. Powder X-ray diffraction analysis showed that the zeolite structure was unaffected by the introduction of the Sn-phase. Diffuse reflectance UV/VIS spectra of the Sn-Z samples confirmed the presence of SnO2 and X-Ray absorption spectroscopy analyses suggested that the SnO2 particles mainly resided on the surface of the clinoptilolite, while ATR-FTIR analysis gave some clues that part of the SnO2 phase was incorporated in the pores of the zeolite. The presence of SnO2 in Sn-Z increased both adsorption capacity and photocatalytic performance which could be partially explained by higher surface area and partially with an increased negative po...
Archives of Industrial Hygiene and Toxicology, 2020
Due to the development of resistance to antimicrobial agents, bacterium Acinetobacter baumannii i... more Due to the development of resistance to antimicrobial agents, bacterium Acinetobacter baumannii is nowadays a leading cause of nosocomial outbreaks. Clinically relevant A. baumannii outside hospital settings including natural soils affected by human waste represents a public-health risk for humans and animals. The aim of this study was to investigate the potential of metal-loaded zeolites to eliminate viable A. baumannii from artificially contaminated natural soils. A. baumannii isolate was subjected to the activity of natural zeolitised tuff (NZ) and Cu-modified (CuNZ) or Ag-modified zeolite (AgNZ) in wet, slightly acidic terra rossa and slightly alkaline red palaeosol. A. baumannii survived in terra rossa and red palaeosol supplemented with 1 wt% of NZ for seven days and four months, respectively. The addition of 1 wt% of CuNZ to terra rossa and red palaeosol shortened the survival of A. baumannii to three and 14 days, respectively. The addition of 0.1 wt% of AgNZ to both soils re...
Water Air and Soil Pollution, Dec 6, 2013
A macroporous, hydrophobically modified poly(acrylic acid-acrylamide) hydrogel was prepared. The ... more A macroporous, hydrophobically modified poly(acrylic acid-acrylamide) hydrogel was prepared. The fourier transform infrared (FTIR) spectrum and field emission scanning electron microscopy (FE-SEM) results showed that the hydrogel had a macroporous structure. The dynamic swelling and removal of cationic dyes, crystal violet (CV) and basic magenta (BM), by this macroporous hydrophobically modified poly(acrylic acidacrylamide) hydrogel were studied. The adsorption capacity and kinetic and isotherm studies of the cationic dyes into the hydrogels have been evaluated. It was found that the macroporous hydrophobically modified hydrogel (M) exhibited improved swelling and adsorption capacity compared with the non-macroporous hydrophobically modified hydrogel (NM). The adsorption process agreed very well with the Langmuir model and the adsorption of the cationic dyes depended on the pH of the solution via a mechanism combining swelling, electrostatic, and hydrophobic interactions. Moreover, adsorption kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model, indicating that chemical adsorption was the rate-limiting step.
Minerals, 2021
The adsorption of the antibiotic ciprofloxacin (CIP) from an aqueous solution by natural zeolite,... more The adsorption of the antibiotic ciprofloxacin (CIP) from an aqueous solution by natural zeolite, the calcium-rich clinoptilolite (CLI), and magnetite-coated CLI (MAG-CLI) was investigated. Both CLI and MAG-CLI showed a high adsorption affinity towards CIP at 283, 288 and 293 K at a pH of 5. Adsorption kinetics studied for the initial concentrations of 15–75 mg CIP dm−3 follow Lagergren’s pseudo-second order equation and the adsorption is best represented by the Langmuir model. The adsorption mechanism involves strong electrostatic interactions between negatively charged aluminosilicate lattice and the cationic form of CIP accompanied by an ion-exchange reaction. Magnetite coverage (approx. 12 wt.%) induces magnetism, which can facilitate the separation process. The coverage does not influence the adsorption activity of CLI. The leaching test showed that the MAG coating protects the adsorbent from CIP leaching. This is ascribed to interactions between the CIP carboxyl groups and mag...
Microporous and Mesoporous Materials, May 1, 2016
In this study the uptake capacity of Mn(II) ions by zeolite A beads was investigated for differen... more In this study the uptake capacity of Mn(II) ions by zeolite A beads was investigated for different initial Mn concentration (100-400 mg Mn dm-3) in batch mode at 25-55 ºC. The obtained adsorption capacity varying from 30 to 50 mg Mn g-1 demonstrated a high affinity of zeolite A towards Mn(II) present in solutions. Kinetic studies indicated the intra-particle diffusion as the rate limiting step up to 45 °C with apparent diffusivities in the range (1.2-2.0)×10-13 m 2 s-1 and the activation energy of 21.9 kJ mol-1 , which implies strong interactions between the zeolite A and Mn ions. At 55 °C ion-exchange became the rate limiting step. The adsorption isotherms were studied at 25 o C showing that the Mn adsorption is the best described by the Langmuir model suggesting a homogenous zeolite surface. XPS analysis of the Mn-loaded beads showed that there is no surface accumulation of Mn but an almost uniform Mn distribution inside zeolite A, whereas XANES and EXAFS suggested that the adsorption of Mn(II) was followed by the Mn(II) oxidation and oxide formation. Regeneration of the spent zeolite was examined in 8 adsorption/desorption cycles by a chelating Na 2 EDTA in a fluidized column. It has been found that zeolite A beads could be reused for at least 4 cycles with satisfactory Mn(II) adsorption efficiencies of about 70 %.
Book of abstracts, Jun 23, 2013
Catalysts, Feb 19, 2020
Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety... more Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety of applications. We report on the photocatalytic activity of a readily available and inexpensive natural zeolite clinoptilolite (Z) containing SnO 2 (Sn-Z). The Sn-Z samples with 3-15 wt. % of Sn were prepared by using a precipitation-deposition method. Powder X-ray diffraction analysis showed that the zeolite structure was unaffected by the introduction of the Sn-phase. Diffuse reflectance UV/VIS spectra of the Sn-Z samples confirmed the presence of SnO 2 and X-Ray absorption spectroscopy analyses suggested that the SnO 2 particles mainly resided on the surface of the clinoptilolite, while ATR-FTIR analysis gave some clues that part of the SnO 2 phase was incorporated in the pores of the zeolite. The presence of SnO 2 in Sn-Z increased both adsorption capacity and photocatalytic performance which could be partially explained by higher surface area and partially with an increased negative potential of the surface. Adsorption and total degradation of methylene blue (MB) for the Sn-Z with the highest amount of Sn (15 wt.%) was about 30% and 45%, respectively, suggesting a synergetic effect between SnO 2 and the clinoptilolite lattice. Reusability tests showed that these catalysts present a promising material for water purification.
Food Technology and Biotechnology
Research background. In the recent years, considerable attention has been given to selenium statu... more Research background. In the recent years, considerable attention has been given to selenium status since its deficiency is linked with various disorders and affects at least 13 % of world population. Additionally, mushrooms are known to possess pronounced capacity for absorption of various micronutrients, including Se, from soil/substrate. Here, we investigate the possibility of using Se-rich zeolitic tuff as a supplement for production of selenized mushroom. Furthermore, the impact of the enrichment on the activity of antioxidant enzymes and biological potential of Coriolus versicolor medicinal mushroom is studied. Experimental approach. Se(IV)- and Se(VI)-modified natural zeolitic tuff from the Serbian deposit Zlatokop was used as supplement for mushroom cultivation. To examine the effectiveness of selenium enrichment, we determined total selenium with inductively coupled plasma mass spectrometry (ICP-MS), together with the activity of antioxidant enzymes in fresh fruiting bodies ...
Catalysts, 2022
The present study focuses on clinoptilolite (CLI)-rich natural zeolitic tuffs and their photocata... more The present study focuses on clinoptilolite (CLI)-rich natural zeolitic tuffs and their photocatalytic activity in the degradation of cationic organic dyes. CLI from different regions was tested in the photocatalytic degradation of methylene blue (MB) as a model cationic dye. The photocatalytic tests were performed at room temperature and atmospheric pressure under visible light irradiation. For all the CLI samples, the highest activity was observed at pH = 6. Total MB degradation varied between 70 and 91% (C0 = 10 mg dm–3, 0.2 g dm–3 of photocatalyst, during 300 min). It is suggested that the presence of Fe species in the studied tuffs is responsible for the photocatalytic activity. The activity increases linearly with the Fe content in the tuffs. The MB photodegradation follows the Langmuir–Hinshelwood kinetic model. The recyclability tests showed good stability and efficiency of the photocatalyst. The degradation rate decreased from 91 to 69% during three reaction cycles, indicat...
Croatica Chemica Acta, 1999
Diffuse-reflectance spectroscopy (DRS), X-ray absorption near-edge structure (XANES) and extended... more Diffuse-reflectance spectroscopy (DRS), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) methods are applied to an investigation of Mn, Co and Ni local environments in MnAlPO, CoAlPO, and NiAlPO materials with chabazite-like topology. For all three products, insertion of the transition metals into tetrahedral Al-sites has been found. Calcination and rehydration of the as-synthesised materials cause a change of the oxidation number and co-ordination geometry of Mn and Co, while the oxidation and co-ordination number of Ni remain unaffected.
Minerals, Jun 29, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Desalination and Water Treatment, Oct 7, 2015
AbstractSorption of the Zn2+ and Ni2+ ions by the Na+-enriched natural clinoptilolite (Na-CLI) fr... more AbstractSorption of the Zn2+ and Ni2+ ions by the Na+-enriched natural clinoptilolite (Na-CLI) from aqueous solutions containing both Zn2+ and Ni2+ ions at a range of concentrations has been studied at 298, 308, and 318 K. It was found that the sorption of a particular ion by Na-CLI increases with the increase in the initial concentration of the solution of that ion. At a given initial concentration, the sorption degree increases with temperature. Also, the sorption of a particular ion is greater when the initial solution contains a second ion than it is when the particular ion is present alone. The sorption kinetics is in accord with the pseudo-second-order reaction rate model. The values of the k2 rate constant do not show a regular change with the initial Zn2+/Ni2+ concentrations probably because the presence of the second ion has a significant effect on the reaction rate. Thermodynamic study has shown that the sorption is exothermic, occurring spontaneously in the 298–318 K range and with a positive e...
ChemInform, Aug 23, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Elsevier eBooks, 2008
The thermal degradation of cetyltrimethylammonium bromide (CTMAB) inside the mesoporous SBA-3 was... more The thermal degradation of cetyltrimethylammonium bromide (CTMAB) inside the mesoporous SBA-3 was studied under non-isothermal conditions. There are two distinct and complex kinetic processes which partly overlap, each consisting of one dominant and three minor individual processes. The two dominant processes can be described by the Sestak-Berggren model. The main decomposition step (the first dominant process) involves the overcoming of weak interactions between CTMAB and the silica network and proceeds with a lower E a value (116±2 kJ mol-1) than the second dominant process (153±5 kJ mol-1), which can be explained by the size reduction of the pore openings due to the contraction of the SBA-3 unit cell caused by the removal of CTMAB.
Minerals, May 14, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Acta Crystallographica Section A, Aug 25, 2000
ECM Nancy s387 conference abstracts o.m3.p1 The true symmetry of [H 3 NCH 2 CH 2 NH 3 ] 2 [FeO(PO... more ECM Nancy s387 conference abstracts o.m3.p1 The true symmetry of [H 3 NCH 2 CH 2 NH 3 ] 2 [FeO(PO 4) 4 ] ⋅ H 2 O with an open-framework structure.
Australian Journal of Chemistry, 1991
The SAPO, MeAPO and MeSAPO microporous materials (Me=co2+ and/or 2n2+) having a sodalite structur... more The SAPO, MeAPO and MeSAPO microporous materials (Me=co2+ and/or 2n2+) having a sodalite structure have been obtained hydrothermally at 200°C in the presence of tetramethylammonium ion as the template. The SAPO and MeSAPO products prepared at lower template concentrations are formed through a partial replacement of both aluminium and phosphorus by silicon in the parent aluminophosphate lattice; at higher pH only phosphorus is replaced. While the ~e~+ ions are in all cases constituents of the framework, most zinc-containing materials have a fraction of the zn2+ ions located in the cavities. T.g.a. shows that complete removal of the trapped organic component can not be easily accomplished. This can be explained by the small size of the openings in the sodalite cages. Powder diffraction analysis shows that replacement of aluminium by silicon, cobalt and zinc, and phosphorus by silicon leads to an expansion of the parent aluminophosphate unit cell. Kinetic studies suggest that crystallization of the silicon-containing products is preceded by an induction period of about 2 h, the nucleation taking place both in the liquid and solid phase.