scholarly journals AQUEOUS SOLUTIONS OF CHITOSAN: VISCOMETRIC AND FLOCCULATION PROPERTIES

2021 ◽  
Vol 2021 ◽  
pp. 123-130
Author(s):  
C.-E. Brunchi ◽  
L. Ghimici
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Zeta Potential ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Polymer Concentration ◽  
Pyrethroid Insecticides ◽  
Vis Spectroscopy ◽  
Insecticide Concentration ◽  
Maximum Removal

The hydrodynamic and flocculation properties of aqueous solution of chitosan (CS) were investigated at room temperature. The viscometric data of dilute CS solutions were discussed in terms of Wolf method as a function of polymer concentration, salt nature (NaCl, NaNO3, and CaCl2) and concentration. The flocculation properties in emulsions of some commercial pyrethroid insecticides (Fastac 10 EC (F), Decis (Dc) and Karate Zeon (KZ)) were evaluated. The viscosity measurements reveal that the experimental data fit well with the Wolf model and the [η] values decrease in salt aqueous solutions. For the same insecticide concentration (0.02%, v/v), UV-Vis spectroscopy measurements show maximum removal efficiency around 90% for Fastac 10EC and Decis and 80% for Karate Zeon. The residual KZ absorbance decreased with the increase of insecticide concentration in the initial emulsion, from 80% for the lowest concentration (0.02%, v/v) to around 90% for the highest one (0.06%, v/v). The supernatant zeta potential dependence on the chitosan dose pleads for the charge neutralization as the main mechanism for the flocculation of pyrethroid insecticide particles.

scholarly journals On the Aqueous Solution Behavior of C-Substituted 3,1,2-Ruthenadicarbadodecaboranes

Inorganics ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 91 ◽  
Author(s):  
Marta Gozzi ◽  
Benedikt Schwarze ◽  
Peter Coburger ◽  
Evamarie Hey-Hawkins
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Self Assembly ◽  
Self Assembling ◽  
Vis Spectroscopy ◽  
Assembly Behavior ◽  
Biological Performance ◽  
Type 3

3,1,2-Ruthenadicarbadodecaborane complexes bearing the [C2B9H11]2− (dicarbollide) ligand are robust scaffolds, with exceptional thermal and chemical stability. Our previous work has shown that these complexes possess promising anti-tumor activities in vitro, and tend to form aggregates (or self-assemblies) in aqueous solutions. Here, we report on the synthesis and characterization of four ruthenium(II) complexes of the type [3-(η6-arene)-1,2-R2-3,1,2-RuC2B9H9], bearing either non-polar (R = Me (2–4)) or polar (R = CO2Me (7)) substituents at the cluster carbon atoms. The behavior in aqueous solution of complexes 2, 7 and the parent unsubstituted [3-(η6-p-cymene)-3,1,2-RuC2B9H11] (8) was investigated via UV-Vis spectroscopy, mass spectrometry and nanoparticle tracking analysis (NTA). All complexes showed spontaneous formation of self-assemblies (108–109 particles mL−1), at low micromolar concentration, with high polydispersity. For perspective applications in medicine, there is thus a strong need for further characterization of the spontaneous self-assembly behavior in aqueous solutions for the class of neutral metallacarboranes, with the ultimate scope of finding the optimal conditions for exploiting this self-assembling behavior for improved biological performance.

The Removal of Strontium(II) and Neodymium(III) from their Aqueous Solutions on Chrysotile Nanotubes

2014 ◽  
Vol 881-883 ◽  
pp. 519-524 ◽  
Author(s):  
Lei Lei Cheng ◽  
Xiao Dong Wei ◽  
Xiao Lei Hao ◽  
Di Ruan ◽  
Shao Ming Yu
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Hydrothermal Method ◽  
Adsorption Mechanism ◽  
Langmuir Model ◽  
Isotherm Models ◽  
Equilibrium Isotherm ◽  
Adsorption Capacities ◽  
Adsorption Desorption

In this research, chrysotile nanotubes (ChNTs) were synthesized by the hydrothermal method. Synthetic ChNTs were characterized using XRD, SEM, TEM and N2adsorption-desorption. Adsorption technique was applied for removal of Sr (II) and Nd (III) from aqueous solution by using ChNTs. The process had been investigated as a function of pH and temperature. The experimental data were analyzed using equilibrium isotherm models. The adsorption isotherms are fitted well by Langmuir model, having a maximum adsorption capacities of 102.56 mg·g-1for Sr (II) and 47.44 mg·g-1for Nd (III) at 298 ± 1 K. FTIR and XPS techniques were employed to investigate possible adsorption mechanism.

Molecular simulation of osmometry in aqueous solutions of the BMIMCl ionic liquid: a potential route to force field parameterization of liquid mixtures

2020 ◽  
Vol 22 (48) ◽  
pp. 28325-28338
Author(s):  
Debdas Dhabal ◽  
Tanmoy Patra
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Ionic Liquid ◽  
Aqueous Solutions ◽  
Force Field ◽  
Molecular Simulation ◽  
Osmotic Coefficient ◽  
Force Fields ◽  
Liquid Mixtures ◽  
Force Field Parameterization

By means of molecular simulation, the osmotic coefficient of aqueous solution of BMIMCl ionic liquid is calculated to compare with the experimental data and use that to optimize two popular force fields available in the literature for bulk ILs.

Time-resolved ESR study on photochemical formation of radical pair in cyclodextrin cavities

1991 ◽  
Vol 69 (11) ◽  
pp. 1643-1648 ◽  
Author(s):  
Hisao Murai ◽  
Yoshinori Yamamoto ◽  
Yasumasa J. I'Haya
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Spin Polarization ◽  
Room Temperature ◽  
Radical Pair ◽  
Ion Pair ◽  
Time Resolved ◽  
Excited Triplet ◽  
Photochemical Formation ◽  
Fixed Orientation

The photoreduction of xanthone with diethylaniline in cyclodextrin cavities was studied at 77 K and room temperature by a time-resolved ESR technique. The radical pair observed in β- and γ-cyclodextrins showed inverted spin polarization compared to that of precursor excited triplet xanthone. This result is rationalized by taking account of the fixed orientation of the radical ion pair in the cyclodextrins. Frozen aqueous solutions and dried powder-like samples provided similar results. The spectrum of the radical pair was also detected in an aqueous solution of β-cyclodextrin at room temperature. Key words: cyclodextrins, xanthone, spin polarization, radical ion-pair, time-resolved ESR.

Adsorption Characteristics of Pb(II) from Aqueous Solution onto Na-Bentonite/Poly AMPS Composite

2012 ◽  
Vol 503-504 ◽  
pp. 658-661
Author(s):  
Hai Yan Xiao ◽  
Kai Sha Gao ◽  
Qiu Rong Li
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Correlation Coefficient ◽  
Adsorption Model ◽  
Adsorption Characteristics ◽  
Optimum Ph

Na-bentonite/poly AMPS composite were prepared as an adsorbent for the removal of Pb (Ⅱ) from aqueous solutions. Pb (Ⅱ) adsorption experiments show the optimum pH and the bentonite content are pH 4.0 and 5g Na-bentonite /10g AMPS, respectively. Experimental data were described by Langmuir and Freundlih isotherms, and the correlation coefficient (R2) shows that the adsorption follows the Freundlich adsorption model.

scholarly journals Two-dimensional monolayer salt nanostructures can spontaneously aggregate rather than dissolve in dilute aqueous solutions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenhui Zhao ◽  
Yunxiang Sun ◽  
Weiduo Zhu ◽  
Jian Jiang ◽  
Xiaorong Zhao ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Md Simulations ◽  
Free Energy Calculations ◽  
Zigzag Chain ◽  
Two Dimensional ◽  
Nucleation Behavior ◽  
Dilute Aqueous Solution ◽  
Dilute Aqueous Solutions

AbstractIt is well known that NaCl salt crystals can easily dissolve in dilute aqueous solutions at room temperature. Herein, we reported the first computational evidence of a novel salt nucleation behavior at room temperature, i.e., the spontaneous formation of two-dimensional (2D) alkali chloride crystalline/non-crystalline nanostructures in dilute aqueous solution under nanoscale confinement. Microsecond-scale classical molecular dynamics (MD) simulations showed that NaCl or LiCl, initially fully dissolved in confined water, can spontaneously nucleate into 2D monolayer nanostructures with either ordered or disordered morphologies. Notably, the NaCl nanostructures exhibited a 2D crystalline square-unit pattern, whereas the LiCl nanostructures adopted non-crystalline 2D hexagonal ring and/or zigzag chain patterns. These structural patterns appeared to be quite generic, regardless of the water and ion models used in the MD simulations. The generic patterns formed by 2D monolayer NaCl and LiCl nanostructures were also confirmed by ab initio MD simulations. The formation of 2D salt structures in dilute aqueous solution at room temperature is counterintuitive. Free energy calculations indicated that the unexpected spontaneous salt nucleation behavior can be attributed to the nanoscale confinement and strongly compressed hydration shells of ions.

scholarly journals Aggregation of Cyanine Dye in Bilayer Vesicles of Phospholipids

2005 ◽  
Vol 4 (3) ◽  
Author(s):  
Casey McCullough ◽  
Matthew Heywood ◽  
Hussein Samha
Keyword(s):  
Aqueous Solution ◽  
Equilibrium Constant ◽  
Room Temperature ◽  
Aggregation Number ◽  
Cyanine Dye ◽  
Molar Ratio ◽  
Isosbestic Point ◽  
Dye Molecules ◽  
Vis Spectroscopy ◽  
J Aggregates

The effect of phospholipid, 1,2-Dipalmitoyl-sn-glycero-3-Phosphocholine (DPPC) on the spectroscopy of the cyanine dye, 1-ethyl-1’-octadecyl-2,2’-cyanine iodide (PIC-18), has been investigated using UV-Vis spectroscopy. Vesicles of DPPC containing PIC-18 in the molar ratio of 1:3 (dye/phospholipids) were prepared in aqueous solution. J-aggregates of PIC-18 were detected in the bilayer wall of the vesicles. When an aqueous solution of mixed PIC-18/DPPC vesicles is treated with excess DPPC vesicles that are prepared separately, the dye molecules in the mixed vesicles underwent a rapid (aggregate)n' n(monomer) equilibrium as the appearance of only one isosbestic point in the absorbance of the dye indicates. The equilibrium constant was calculated at room temperature (Keq = 6.7x10-2). An aggregation number of 4 was calculated for the dye in the bilayer vesicles.

Adsorption of Sn (II) from Aqueous Solutions on Expanded Graphite

2011 ◽  
Vol 347-353 ◽  
pp. 89-93
Author(s):  
Ming Yang ◽  
Ying Hua Zhao ◽  
Ying Chen Zhang ◽  
Deng Xin Li
Keyword(s):  
Aqueous Solution ◽  
Microwave Irradiation ◽  
Aqueous Solutions ◽  
Contact Time ◽  
Removal Rate ◽  
Expanded Graphite ◽  
Adsorption Behavior ◽  
Adsorption Quantity ◽  
Maximum Removal

Expanded graphite (EG) was prepared by microwave irradiation at 1000 w for 60 s. It is a novel adsorbent for Sn (Ⅱ) adsorption. This paper aims to investigate the effect of the adsorption of EG. The adsorption behavior of Sn (Ⅱ) from aqueous solution onto EG was investigated with variety of parameters such as pH, adsorbents dosage, initial Sn (Ⅱ) concentration, contact time and temperature. On conditions that the pH was 2.5, the dosage of adsorbent was 0.02 g, the concentration of Sn (Ⅱ) was 200 mg/L and the temperature was 15°C, the maximum removal rate can reach to 98.32%, and the adsorption quantity can reach to 245.7985 mg•g-1. The results showed that the EG was an efficient and novel adsorbent for the removal of stannum from aqueous solution.

Radiation Chemistry of DNA Model Compounds, IX. Carbohydrate Products in the γ-Radiolysis of Thymidine in Aqueous Solution. The Radical-Induced Scission of the N-Glycosidic Bond

1976 ◽  
Vol 31 (2) ◽  
pp. 227-233 ◽  
Author(s):  
Miral Dizdaroglu ◽  
Klaus Neuwald ◽  
Clemens Von Sonntag
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Radiation Chemistry ◽  
Oh Radical ◽  
Glycosidic Linkage ◽  
Model Compounds ◽  
Sugar Moiety ◽  
G Value ◽  
Radical Attack

In the γ-radiolysis of deoxygenated N2O-saturated aqueous solutions of thymidine (10-3 M, room temperature, dose rate 4· 1018 eV/g.h., dose 6.7 1017-3.3 • 1018 eV/g) the following products (G-values in parentheses) have been identified : 2,5-dideoxy-pentos-4-ulose (1) (0.01), 2,4-dideoxy-pentodialdose (2) (0.02), 2,4-dideoxy-pentos-3-ulose (3) (0.03), 2,3-dideoxy-pentos-4-ulose (4) (0.01), 2-deoxy-pentos-4-ulose (5) (0.1), 2-deoxyribonic acid (6) (0.02) and thymine (8) ( ≤ 0.2). In the presence of oxygen (N2O/O2 80/20 v/v saturated) products 1-4 are absent, G (5) = 0.2, G (6) = 0.07 and G (8) ≤ 0.4. Furthermore, 2-deoxy-tetrodialdose (7) which is absent in deoxygenated solution is formed with a G-value of 0.03. Mechanisms are proposed to account for the scission of the N-glycosidic linkage. Product 6 is thought to be due to a primary OH radical attack at C-1′ of the sugar moiety, 8 arises from an attack at C-3′, 1, 4 and 5 from an attack at C-4′, and 2 and 7 from an attack at C-5′.

scholarly journals Role of Sawdust in the Removal of Iron from Aqueous Solution

2017 ◽  
Vol 23 (3) ◽  
pp. 223 ◽  
Author(s):  
H.B. Senin ◽  
O. Subhi ◽  
R. Rosliza ◽  
N. Kancono ◽  
M.S. Azhar ◽  
...  
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Langmuir Isotherm ◽  
Room Temperature ◽  
Freundlich Isotherm ◽  
Batch Test ◽  
Freundlich Isotherms ◽  
Langmuir And Freundlich Isotherms ◽  
Better Than

Sawdust, inexpensive material has been utilized as an absorbent for the removal of iron from aqueous solution for their safe disposal. The adsorption experiments of untreated sawdust (SD) and treated sawdust (SDC) have been carried out at room temperature using the batch test. The Langmuir and Freundlich isotherms were used to observe sorption phenomena of sawdust in the removal of iron. The results indicate that the sawdust was capable in removing iron in aqueous solution. The results have shown that the Langmuir isotherm was found well fitted into the experimental data as compared to the Freundlich isotherm. It was found that, chemisorptions and physisorption were the prime mechanism for the process of adsorption to occur between the sawdust and iron. The results also proved that the acid sulphuric treated sawdust is much better than that of untreated sawdust as an adsorbent for iron.

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