scholarly journals Synthesis and Characterization of Halloysite/Carbon Nanocomposites for Enhanced NSAIDs Adsorption from Water

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3754 ◽  
Author(s):  
Beata Szczepanik ◽  
Nina Rędzia ◽  
Laura Frydel ◽  
Piotr Słomkiewicz ◽  
Anna Kołbus ◽  
...  
Keyword(s):  
Density Functional ◽  
Structural Changes ◽  
Adsorption Mechanism ◽  
Nitrogen Adsorption ◽  
Infrared Spectrometry ◽  
Adsorption Model ◽  
Adsorption Method ◽  
Carbon Nanocomposites ◽  
Chemical Structures ◽  
Intra Particle Diffusion

The adsorption of ketoprofen, naproxen, and diclofenac (non-steroidal anti-inflammatory drugs, NSAIDs) on halloysite/carbon nanocomposites and non-modified halloysite were investigated in this work. Halloysite/carbon nanocomposites were obtained through liquid phase impregnation and carbonization using halloysite as the template and saccharose as the carbon precursor. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FT-IR), and low-temperature nitrogen adsorption method were employed to study the morphological and structural changes of the halloysite/carbon nanocomposites. The effects of contact time, initial concentration of adsorbates, pH of solution, and mass of adsorbent on the adsorption were studied. Adsorption mechanism was found to fit pseudo-second-order and intra-particle diffusion models. The obtained experimental adsorption data were well represented by the Langmuir multi-center adsorption model. Adsorption ability of halloysite/carbon nanocomposites was much higher for all the studied NSAIDs in comparison to non-modified halloysite. Optimized chemical structures of ketoprofen, naproxen, and diclofenac obtained by Density Functional Theory (DFT) calculation showed that charge distributions of these adsorbate molecules and their ions can be helpful to explain the details of adsorption mechanism of NSAIDs on halloysite/carbon nanocomposites.

scholarly journals Adsorption of Phenol and Chlorophenols by HDTMA Modified Halloysite Nanotubes

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3309
Author(s):  
Piotr Słomkiewicz ◽  
Beata Szczepanik ◽  
Marianna Czaplicka
Keyword(s):  
Liquid Chromatography ◽  
Structural Changes ◽  
Halloysite Nanotubes ◽  
Breakthrough Curves ◽  
Infrared Spectrometry ◽  
Hexadecyltrimethylammonium Bromide ◽  
Adsorption Model ◽  
Adsorption Parameters ◽  
Adsorption Method ◽  
Chromatography Method

The adsorption of phenol, 2-, 3-, 4-chlorophenol, 2-, 4-dichlorophenol and 2-, 4-, 6-trichloro-phenol on halloysite nanotubes modified with hexadecyltrimethylammonium bromide (HDTMA/halloysite nanocomposite) was investigated in this work by inverse liquid chromatography methods. Morphological and structural changes of the HDTMA/halloysite nanocomposite were characterized by scanning and transmission electron microscopy (SEM, TEM), Fourier-transform infrared spectrometry (FT-IR) and the low-temperature nitrogen adsorption method. Specific surface energy heterogeneity profiles and acid base properties of halloysite and HDTMA/halloysite nanocomposite have been determined with the inverse gas chromatography method. Inverse liquid chromatography methods: the Peak Division and the Breakthrough Curves Methods were used in adsorption experiments to determine adsorption parameters. The obtained experimental adsorption data were well represented by the Langmuir multi-center adsorption model.

scholarly journals Surface Properties of Halloysite-Carbon Nanocomposites and Their Application for Adsorption of Paracetamol

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5647
Author(s):  
Beata Szczepanik ◽  
Dariusz Banaś ◽  
Aldona Kubala-Kukuś ◽  
Karol Szary ◽  
Piotr Słomkiewicz ◽  
...  
Keyword(s):  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Adsorption Model ◽  
Xps Spectra ◽  
Carbon Nanocomposites ◽  
Wide Range ◽  
Intra Particle Diffusion ◽  
Pseudo Second Order ◽  
Energy Survey ◽  
Photoelectron Peak

Analysis of surface properties of halloysite-carbon nanocomposites and non-modified halloysite was carried out with surface sensitive X-ray photoelectron spectroscopy (XPS) and inverse gas chromatography (IGC). The XPS spectra were measured in a wide range of the electron binding energy (survey spectra) and in the region of C 1s photoelectron peak (narrow scans). The IGC results show the changes of halloysite surface from basic for pure halloysite to acidic for carbon-halloysite nanocomposites. Halloysite-carbon nanocomposites were used as adsorbents of paracetamol from an aqueous solution. The adsorption mechanism was found to follow the pseudo-second-order and intra-particle diffusion models. The Langmuir multi-center adsorption model described well the obtained experimental data. The presence of carbon increased significantly the adsorption ability of halloysite-carbon nanocomposites for paracetamol in comparison to the non-modified halloysite.

Evaluating Hydrogen Uptake for Two Types of Multi-Wall Carbon Nanotubes from Nitrogen Adsorption/Desorption Data

2017 ◽  
Vol 13 ◽  
pp. 341-347 ◽  
Author(s):  
Dmitry S. Muratov ◽  
Sergey Gromov
Keyword(s):  
Carbon Nanotubes ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Density Functional ◽  
Local Density ◽  
Nitrogen Adsorption ◽  
Hydrogen Uptake ◽  
Adsorption Method ◽  
Multi Wall Carbon Nanotubes

Two types of multi-wall carbon nanotubes (MWCNT) were studied by low temperature nitrogen adsorption method. Pore size distribution was calculated using non local density functional theory (NLDFT) and Barrett-Joyner-Halenda (BJH) models. The peaks on pore size distribution were attributed to MWCNT with different diameters. Maximum hydrogen uptake by weight was evaluated for both samples and do not exceed 5 % even for the sample with higher specific surface area.

scholarly journals Defect Processes in Halogen Doped SnO2

2021 ◽  
Vol 11 (2) ◽  
pp. 551
Author(s):  
Petros-Panagis Filippatos ◽  
Nikolaos Kelaidis ◽  
Maria Vasilopoulou ◽  
Dimitris Davazoglou ◽  
Alexander Chroneos
Keyword(s):  
Electronic Properties ◽  
Tin Oxide ◽  
Density Functional ◽  
Structural Changes ◽  
High Dielectric Constant ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Optical And Electronic Properties ◽  
High Dielectric ◽  
Gap States

In the present study, we performed density functional theory calculations (DFT) to investigate structural changes and their impact on the electronic properties in halogen (F, Cl, Br, and I) doped tin oxide (SnO2). We performed calculations for atoms intercalated either at interstitial or substitutional positions and then calculated the electronic structure and the optical properties of the doped SnO2. In all cases, a reduction in the bandgap value was evident, while gap states were also formed. Furthermore, when we insert these dopants in interstitial and substitutional positions, they all constitute a single acceptor and donor, respectively. This can also be seen in the density of states through the formation of gap states just above the valence band or below the conduction band, respectively. These gap states may contribute to significant changes in the optical and electronic properties of SnO2, thus affecting the metal oxide’s suitability for photovoltaics and photocatalytic devices. In particular, we found that iodine (I) doping of SnO2 induces a high dielectric constant while also reducing the oxide’s bandgap, making it more efficient for light-harvesting applications.

scholarly journals Pore Modification and Phosphorus Doping Effect on Phosphoric Acid-Activated Fe-N-C for Alkaline Oxygen Reduction Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1519
Author(s):  
Jong Gyeong Kim ◽  
Sunghoon Han ◽  
Chanho Pak
Keyword(s):  
Phosphoric Acid ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Electronic States ◽  
Nitrogen Adsorption ◽  
Reduction Reaction ◽  
Phosphorus Doping ◽  
X Ray ◽  
Precious Metal Catalysts ◽  
Adsorption Desorption

The price and scarcity of platinum has driven up the demand for non-precious metal catalysts such as Fe-N-C. In this study, the effects of phosphoric acid (PA) activation and phosphorus doping were investigated using Fe-N-C catalysts prepared using SBA-15 as a sacrificial template. The physical and structural changes caused by the addition of PA were analyzed by nitrogen adsorption/desorption and X-ray diffraction. Analysis of the electronic states of Fe, N, and P were conducted by X-ray photoelectron spectroscopy. The amount and size of micropores varied depending on the PA content, with changes in pore structure observed using 0.066 g of PA. The electronic states of Fe and N did not change significantly after treatment with PA, and P was mainly found in states bonded to oxygen or carbon. When 0.135 g of PA was introduced per 1 g of silica, a catalytic activity which was increased slightly by 10 mV at −3 mA/cm2 was observed. A change in Fe-N-C stability was also observed through the introduction of PA.

scholarly journals Effect of chemical modification on electronic transport properties of carbyne

2021 ◽  
Author(s):  
G. R. Berdiyorov ◽  
U. Khalilov ◽  
H. Hamoudi ◽  
Erik C. Neyts
Keyword(s):  
Transport Properties ◽  
Electronic Transport ◽  
Density Functional ◽  
Structural Changes ◽  
Carbon Chain ◽  
Functional Formalism ◽  
Functional Theory ◽  
Carbon Allotrope ◽  
Electronic Transport Properties ◽  
Interface Structures

AbstractUsing density functional theory in combination with the Green’s functional formalism, we study the effect of surface functionalization on the electronic transport properties of 1D carbon allotrope—carbyne. We found that both hydrogenation and fluorination result in structural changes and semiconducting to metallic transition. Consequently, the current in the functionalization systems increases significantly due to strong delocalization of electronic states along the carbon chain. We also study the electronic transport in partially hydrogenated carbyne and interface structures consisting of pristine and functionalized carbyne. In the latter case, current rectification is obtained in the system with rectification ratio up to 50%. These findings can be useful for developing carbyne-based structures with tunable electronic transport properties.

Computational Studies of Magnesium and Strontium Substitution in Hydroxyapatite

2012 ◽  
Vol 529-530 ◽  
pp. 123-128 ◽  
Author(s):  
Flora E. Imrie ◽  
Marta Corno ◽  
Piero Ugliengo ◽  
Iain R. Gibson
Keyword(s):  
Density Functional ◽  
Structural Changes ◽  
Harmonic Approximation ◽  
Site Preference ◽  
Ionic Radii ◽  
Biologically Relevant ◽  
Site Preferences ◽  
Mechanical Approach ◽  
Quantum Mechanical Approach ◽  
Mg Substitution

The properties of hydroxyapatite can be improved by substitution of biologically relevant ions, such as magnesium (Mg) and strontium (Sr), into its structure. Previous work in the literature has not reached agreement as to site preferences in these substitutions, and there are suggestions that these may change with differing levels of substitution. The current work adopted a quantum mechanical approach based on density functional theory using the CRYSTAL09 code to investigate the structural changes relating to, and site preferences of, magnesium and strontium substitution (to 10 mol%) in hydroxyapatites and also to predict the corresponding vibrational spectra in the harmonic approximation. The structures underwent full geometrical optimisation within the P63 space group, indicating an energetic site preference for the Ca (2) site in the case of Mg substitution, and the Ca (1) site in the case of Sr. Shrinkage of the unit cell was observed in the case of Mg substitution, and expansion in the case of Sr substitution, in agreement with the corresponding ionic radii. Thermodynamic properties of the structures obtained from the harmonic vibrational frequency calculations confirmed that the structures were minima on the potential energy surface. Isotopic substitutions indicated that the main contribution of Sr and Mg to vibrational modes is at frequencies < 400 cm-1.

Extraordinary Stability of Structural and Electronic Properties of Tin Oxide Nanoparticles Formed by Soft Chemistry

2010 ◽  
Vol 75 ◽  
pp. 36-42 ◽  
Author(s):  
Marina Rumyantseva ◽  
Irina Zhurbina ◽  
Elena Varechkina ◽  
Siranuysh Badalyan ◽  
Alexander Gaskov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
Tin Dioxide ◽  
Hydrogen Reduction ◽  
Nitrogen Adsorption ◽  
Ammonia Solution ◽  
Adsorption Method ◽  
X Ray ◽  
Wet Chemical Synthesis ◽  
Tin Chloride

Powders of tin dioxide (SnO2) have been prepared by two different modifications of wet chemical synthesis, i.e. (i) by conventional hydrolysis of tin chloride dissolved in aqueous ammonia solution and (ii) by precipitation from tin chloride dissolved in aqueous hydrazine monohydrate (N2H4*H2O) solution. The prepared gels were dried and then annealed at different temperatures varied from 300 to 700 oC in order to form nanocrystals. Structure and optical properties of the samples were investigated by using X-ray diffraction, transmission electron microscopy, thermoprogrammable hydrogen reduction, low temperature nitrogen adsorption method, photoluminescence, infra-red absorption, Raman spectroscopy, and X-ray photoelectron spectroscopy. The samples prepared by hydrazine-based method are characterized by surface area about 127-188 m2/g with high sintering resistance. The optical spectroscopy data revealed pure crystallinity and high defect concentration for the samples prepared by hydrazine-based method. The experimental results are discussed in view of different states of chemisorbed oxygen on SnO2 nanocrystal surfaces, which determine electronic and optical properties of the prepared samples.

scholarly journals Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Qing Chen ◽  
Yuanyuan Tian ◽  
Peng Li ◽  
Changhui Yan ◽  
Yu Pang ◽  
...  
Keyword(s):  
Adsorption Isotherm ◽  
Shale Gas ◽  
Size Structure ◽  
Capillary Condensation ◽  
Critical Role ◽  
Nitrogen Adsorption ◽  
Adsorption Model ◽  
Multilayer Adsorption ◽  
Nitrogen Adsorption Isotherm ◽  
Monolayer Adsorption

Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indicates that nitrogen adsorption on shale includes monolayer adsorption, multilayer adsorption, and capillary condensation. Usually, Langmuir isotherm is a monolayer adsorption model for ideal interfaces; BET (Brunauer, Emmett, Teller) adsorption isotherm is a multilayer adsorption model based on specific assumptions; Freundlich isotherm is an empirical equation widely applied in liquid phase adsorption. In this study, a new nitrogen adsorption isotherm is applied to simultaneously depict monolayer adsorption, multilayer adsorption, and capillary condensation, which provides more real and accurate representation of nitrogen adsorption on shale. In addition, parameters are discussed in relation to heat of adsorption which is relevant to the shape of the adsorption isotherm curve. The curve fitting results indicate that our new nitrogen adsorption isotherm can appropriately describe the whole process of nitrogen adsorption on shale.

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