scholarly journals A Fractal-Based Correlation for Time-Dependent Surface Diffusivity in Porous Adsorbents

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 689 ◽  
Author(s):  
Vassilis J. Inglezakis ◽  
Marco Balsamo ◽  
Fabio Montagnaro
Keyword(s):  
Surface Diffusion ◽  
Solid Phase ◽  
Time Dependent ◽  
Limited Attention ◽  
Monotonic Trend ◽  
Surface Diffusivity ◽  
Variable Surface ◽  
Adsorption Processes ◽  
Hindered Diffusion ◽  
Hopping Diffusion

Fluid–solid adsorption processes are mostly governed by the adsorbate transport in the solid phase and surface diffusion is often the limiting step of the overall process in microporous materials such as zeolites. This work starts from a concise review of concepts and models for surface transport and variable surface diffusivity. It emerges that the phenomenon of hindered surface diffusion for monolayer adsorption, which is common in zeolites, and models able to fit a non-monotonic trend of surface diffusivity against adsorbate solid phase concentration, have received limited attention. This work contributes to the literature of hindered diffusion by formulating a time-dependent equation for surface diffusivity based on fractal dynamics concepts. The proposed equation takes into account the contributions of both fractal-like diffusion (a time-decreasing term) and hopping diffusion (a time-increasing term). The equation is discussed and numerically analyzed to testify its ability to reproduce the possible different patterns of surface diffusivity vs. time.

scholarly journals NanoMIP-Based Solid Phase Extraction of Fluoroquinolones from Human Urine: A Proof-of-Concept Study

Separations ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 226
Author(s):  
Matteo Chiarello ◽  
Laura Anfossi ◽  
Simone Cavalera ◽  
Fabio Di Di Nardo ◽  
Thea Serra ◽  
...  
Keyword(s):  
Solid Phase Extraction ◽  
Human Urine ◽  
Solid Phase ◽  
Extraction Methods ◽  
Hplc Method ◽  
Limited Attention ◽  
Preliminary Treatment ◽  
Phase Extraction ◽  
Proof Of Concept ◽  
Binding Behavior

NanoMIPs that are prepared by solid phase synthesis have proven to be very versatile, but to date only limited attention has been paid to their use in solid phase extraction. Thus, since nanoMIPs show close similarities, in terms of binding behavior, to antibodies, it seems relevant to verify if it is possible to use them as mimics of the natural antibodies that are used in immunoextraction methods. As a proof-of-concept, we considered prepared nanoMIPs against fluoroquinolone ciprofloxacin. Several nanoMIPs were prepared in water with polymerization mixtures of different compositions. The polymer with the highest affinity towards ciprofloxacin was then grafted onto a solid support and used to set up a solid phase extraction–HPLC method with fluorescence detection, for the determination of fluoroquinolones in human urine. The method resulted in successful selection for the fluoroquinolone antibiotics, such that the nanoMIPs were suitable for direct extraction of the antibiotics from the urine samples at the µg mL−1 level. They required no preliminary treatment, except for a 1 + 9 (v/v) dilution with a buffer of pH 4.5 and they had good analyte recovery rates; up to 85% with precision in the range of 3 to 4.5%, without interference from the matrix. These experimental results demonstrate, for the first time, the feasibility of the use of nanoMIPs to develop solid phase extraction methods.

scholarly journals Formation of a Thin Continuous GaSb Film on Si(001) by Solid Phase Epitaxy

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 987 ◽  
Author(s):  
Evgeniy Chusovitin ◽  
Sergey Dotsenko ◽  
Svetlana Chusovitina ◽  
Dmitry Goroshko ◽  
Anton Gutakovskii ◽  
...  
Keyword(s):  
Surface Diffusion ◽  
Annealing Temperature ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
20 Nm

Nanocrystalline GaSb films were grown on Si(001) from the stoichiometric Ga–Sb mixture using solid-phase epitaxy at temperatures of 200–500 °C. Use of the solid-phase epitaxy method allowed the suppression of Ga surface diffusion and prevention of intense Sb desorption. At the annealing temperature of 300 °C, a 14-nm-thick GaSb film aggregates, while a 20-nm-thick GaSb film remains continuous with a roughness of 1.74 nm. A GaSb film with a thickness of 20 nm consists of crystalline grains with a size of 9–16 nm. They were compressed by ~2%. For some GaSb grains, new epitaxial relationships have been found: GaSb ( 111 ) ||Si ( 11 1 ¯ ) and GaSb [ 11 2 ¯ ] ||Si [ 1 1 ¯ 0 ] , GaSb ( 113 ) ||Si ( 11 1 ¯ ) and GaSb [ 1 1 ¯ 0 ] ||Si [ 1 1 ¯ 0 ] , and GaSb ( 11 1 ¯ ) ||Si ( 002 ) and GaSb [ 1 1 ¯ 0 ] ||Si [ 1 1 ¯ 0 ] .

scholarly journals Cocrystal Formation through Solid-State Reaction between Ibuprofen and Nicotinamide Revealed Using THz and IR Spectroscopy with Multivariate Analysis

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 760
Author(s):  
Sae Ishihara ◽  
Yusuke Hattori ◽  
Makoto Otsuka ◽  
Tetsuo Sasaki
Keyword(s):  
Ir Spectroscopy ◽  
Solid Phase ◽  
Time Dependent ◽  
Multivariate Curve Resolution ◽  
Thz Spectroscopy ◽  
Water Molecules ◽  
Active Pharmaceutical Ingredients ◽  
Curve Resolution ◽  
Pharmaceutical Ingredients ◽  
Solid Phase Reactions

Cocrystallisation can enhance the solubility and bioavailability of active pharmaceutical ingredients (APIs); this method may be applied to improve the availability of materials that were previously considered unsuitable. Terahertz (THz) spectroscopy provides clear, substance-specific fingerprint spectra; the transparency of the THz wave allows us to probe inside a sample to identify medicinal materials. In this study, THz and infrared (IR) spectroscopy were used to characterise cocrystallisation in solid-phase reactions between ibuprofen and nicotinamide. Multivariate curve resolution with alternating least squares (MCR-ALS) was applied to both time-dependent THz and IR spectra to identify the intermolecular interactions between these cocrystallising species. The analytical results revealed cocrystal formation through a two-step reaction, in which the steps were dominated by thermal energy and water vapour, respectively. We infer that the presence of water molecules significantly lowered the activation energy of cocrystal formation.

scholarly journals Evaluation of an Experimentally Designed Molecular Imprinted Polyurethane Foam Performance for Extraction of Alprazolam

2019 ◽  
Vol 57 (7) ◽  
pp. 662-670
Author(s):  
Zeynab Tavakoli ◽  
Majid Soleimani ◽  
Mir Mohammad Alavi Nikje
Keyword(s):  
Polyurethane Foam ◽  
High Efficiency ◽  
Solid Phase ◽  
Selective Adsorption ◽  
Selective Extraction ◽  
Extraction Methods ◽  
Effective Parameters ◽  
Rigid Foam ◽  
Adsorption Processes ◽  
Central Composite

Abstract Industrial polyurethane rigid foam (PUF) was selected as a substrate for selective solid phase extraction of Alprazolam. Effective parameters for raising selectivity of the PUF were evaluated. Synthetic molecularly imprinted polyurethane foam (MIPUF) was tracked as selective adsorbent and its characteristic was pondered by analytical methods. Optimization was done by central composite design (CCD) to have high efficiency of the polymer adsorption. Two different extraction methods were compared in the selective adsorption processes using MIPUF and NIPUF, batch system and continuous (cartridge) system. Results of the adsorption of alprazolam on the MIPUF had 39% more recovery than NIPUF (reference polymer). Then, the proposed method suggests a selective extraction of mentioned analyte from urine and tablets as complex matrixes.

Pore-Surface Diffusion Model for Batch Adsorption Processes

Langmuir ◽  
2003 ◽  
Vol 19 (10) ◽  
pp. 4188-4196 ◽  
Author(s):  
Chi-Wai Hui ◽  
Buning Chen ◽  
Gordon McKay
Keyword(s):  
Surface Diffusion ◽  
Diffusion Model ◽  
Batch Adsorption ◽  
Pore Surface ◽  
Adsorption Processes

Enhanced Surface Diffusion in Low-temperature a-Si:H Processing

2004 ◽  
Vol 808 ◽  
Author(s):  
George T. Dalakos ◽  
Joel L. Plawsky ◽  
Peter D. Persans
Keyword(s):  
Surface Roughness ◽  
Surface Diffusion ◽  
Room Temperature ◽  
Cathodic Deposition ◽  
Hydrogenated Silicon ◽  
Surface Diffusivity ◽  
Amorphous Hydrogenated Silicon ◽  
Anodic Deposition ◽  
Enhanced Surface ◽  
Global Parameters

ABSTRACTGlow discharge amorphous hydrogenated silicon (a-Si:H) prepared at near room temperature typically results in an inhomogeneous morphology that is undesirable for a number of thin film applications. The most commonly observed features of this include columnar morphology and surface roughness. This usually results from anodic deposition, where substrates are placed on the grounded electrode. We have discovered that placing substrates on the RF-powered electrode (referred to as cathodic deposition) offers a much wider processing range for homogenous growth than anodic growth. We have also found that the magnitude of the surface roughness and the bulk void fraction of both anodic and cathodic a-Si:H thin films processed at low-temperatures is proportional to ∼D/F, where D is the surface diffusivity and F, the adatom flux, though anodic and cathodic deposition affect these global parameters differently. Surface processes unique to cathodic deposition can enhance adatom surface diffusion, while diffusion during anodic deposition is fixed and cannot attain homogeneous growth at high adatom fluxes. Processing a-Si:H on the cathode, associated with enhanced adatom surface diffusion, allows for homogeneous growth even at high deposition rates that has benefits for a number of applications.

scholarly journals The Analysis of Low-Cost Pb(II) Adsorbents using Batch Method of Solid-Phase Spectrophotometry

2021 ◽  
Vol 1 (1) ◽  
pp. 38-45
Author(s):  
Sulistyo Saputro ◽  
Ashadi Ashadi ◽  
Lina Mahardiani ◽  
Nurma Yunita Indriyanti ◽  
Maria Ciptaning Sabdo Kawedhar ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Rice Husk ◽  
Natural Zeolite ◽  
Metal Ion ◽  
Solid Phase ◽  
Health Problems ◽  
Single Beam ◽  
Adsorption Processes ◽  
Simulated Wastewater ◽  
Solid Phase Spectrophotometry

Heavy metal pollutants contained in wastewater can cause health problems for living things around. Minor to fatal health problems can occur due to heavy metal poisoning, mainly caused by Pb(II) metal.. This study aimed to determine the optimum mass combination of rice husk and zeolite to adsorb Pb(II) metal ions in simulated wastewater, and to determine the sensitivity of the analysis method. This study used Solid Phase Spectrophotometry (SPS) to determine the decrease in Pb(II) metal ion levels after being adsorbed by activated carbon from rice husks and zeolites. This study used an experimental method with simulated wastewater samples containing Pb(II) at several concentrations. Pb(II) adsorption processes by rice husk and natural zeolite used various adsorbents' mass ratios. The adsorbents were characterized by using Fourier-Transform Infra-Red (FTIR) Spectrophotometry. Pb(II) analysis during adsorption processes used a single beam UV-visible Spectrophotometer for Solid-Phase Spectrophotometry. This study indicates that the combination of adsorbent from rice husk and natural zeolite can properly adsorb Pb(II) ions with an adsorption capacity of 0.75 μg g-1 and 0.025 μg L-1 for the LoD of the instrument.

The Analysis of Low-Cost Pb(II) Adsorbents using Batch Method of Solid-Phase Spectrophotometry

2021 ◽  
Vol 7 (1) ◽  
pp. 38-45
Author(s):  
Sulistyo Saputro ◽  
Ashadi Ashadi ◽  
Lina Mahardiani ◽  
Nurma Yunita Indriyanti ◽  
Maria Ciptaning Sabdo Kawedhar ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Rice Husk ◽  
Natural Zeolite ◽  
Metal Ion ◽  
Solid Phase ◽  
Health Problems ◽  
Single Beam ◽  
Adsorption Processes ◽  
Simulated Wastewater ◽  
Solid Phase Spectrophotometry

Heavy metal pollutants contained in wastewater can cause health problems for living things around. Minor to fatal health problems can occur due to heavy metal poisoning, mainly caused by Pb(II) metal.. This study aimed to determine the optimum mass combination of rice husk and zeolite to adsorb Pb(II) metal ions in simulated wastewater, and to determine the sensitivity of the analysis method. This study used Solid Phase Spectrophotometry (SPS) to determine the decrease in Pb(II) metal ion levels after being adsorbed by activated carbon from rice husks and zeolites. This study used an experimental method with simulated wastewater samples containing Pb(II) at several concentrations. Pb(II) adsorption processes by rice husk and natural zeolite used various adsorbents' mass ratios. The adsorbents were characterized by using Fourier-Transform Infra-Red (FTIR) Spectrophotometry. Pb(II) analysis during adsorption processes used a single beam UV-visible Spectrophotometer for Solid-Phase Spectrophotometry. This study indicates that the combination of adsorbent from rice husk and natural zeolite can properly adsorb Pb(II) ions with an adsorption capacity of 0.75 μg g-1 and 0.025 μg L-1 for the LoD of the instrument.

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