Disintegration of Hexagonal NaYF4:Yb3+,Er3+ Upconverting Nanoparticles in Aqueous Media: The Role of Fluoride in Solubility Equilibrium

2016 ◽  
Vol 121 (1) ◽  
pp. 656-665 ◽  
Author(s):  
Satu Lahtinen ◽  
Annika Lyytikäinen ◽  
Henna Päkkilä ◽  
Emmy Hömppi ◽  
Niina Perälä ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Solubility Equilibrium

scholarly journals Uptake of Methylene Blue from Aqueous Solution by Pectin–Chitosan Binary Composites

2020 ◽  
Vol 4 (3) ◽  
pp. 95
Author(s):  
Dexu Kong ◽  
Lee D. Wilson
Keyword(s):  
Methylene Blue ◽  
Aqueous Media ◽  
Dye Adsorption ◽  
Adsorption Properties ◽  
Point Of Zero Charge ◽  
Cross Linking ◽  
Gravimetric Analysis ◽  
Adsorption Sites ◽  
Biopolymer Composites

To address the need to develop improved hybrid biopolymer composites, we report on the preparation of composites that contain chitosan and pectin biopolymers with tunable adsorption properties. Binary biopolymer composites were prepared at variable pectin–chitosan composition in a solvent directed synthesis, dimethyl sulfoxide (DMSO) versus water. The materials were characterized using complementary methods (infrared spectroscopy, thermal gravimetric analysis, pH at the point-of-zero charge, and dye-based adsorption isotherms). Pectin and chitosan composites prepared in DMSO yielded a covalent biopolymer framework (CBF), whereas a polyelectrolyte complex (PEC) was formed in water. The materials characterization provided support that cross-linking occurs between amine groups of chitosan and the –COOH groups of pectin. CBF-based composites had a greater uptake of methylene blue (MB) dye over the PEC-based composites. Composites prepared in DMSO were inferred to have secondary adsorption sites for enhanced MB uptake, as evidenced by a monolayer uptake capacity that exceeded the pectin–chitosan PECs by 1.5-fold. This work provides insight on the role of solvent-dependent cross-linking of pectin and chitosan biopolymers. Sonication-assisted reactions in DMSO favor CBFs, while cross-linking in water yields PECs. Herein, composites with tunable structures and variable physicochemical properties are demonstrated by their unique dye adsorption properties in aqueous media.

Commercial Dental Composite: Determination of Reaction Advancement and Study of the Migration of Organic Compounds

2005 ◽  
Vol 13 (3) ◽  
pp. 223-234
Author(s):  
C. Sanglar ◽  
M. Defay ◽  
H. Waton ◽  
A. Bonhomme ◽  
S. Alamercery ◽  
...  
Keyword(s):  
Artificial Saliva ◽  
Aqueous Media ◽  
Dental Composite ◽  
Dental Composites ◽  
Hydrophilic Monomer ◽  
Methacrylate Monomers ◽  
Urethane Dimethacrylate ◽  
Hydrolysis Of

This work on organic dental composites was undertaken to determine the role of residual reactive methacrylate functions at the end of the photopolymerization cycle, and to investigate the fate of the residual monomers and oligomers in organic (ethanol) and aqueous (water and artificial saliva) media. The results show that all the methacrylate monomers present in dentine migrate into ethanol (about 1% (w/w)). In aqueous media on the other hand, only the most hydrophilic monomer (UDMA) migrates (0.05% (w/w)) into water and 0.03% into artificial saliva (pH = 9). This desorption in the three media is accompanied by the hydrolysis of monomers, leading to the formation of monohydrolyzed urethane dimethacrylate (UDMA) and bis-phenyl glycidyl dimethacrylate (BISGMA); UDMA and BISGMA are completely hydrolyzed in artificial saliva. The alkalinity of the milieu apparently favours the hydrolysis of methacrylate functions.

Role of nanoparticles in analytical solid phase microextraction (SPME)

2013 ◽  
Vol 10 (2) ◽  
pp. 120 ◽  
Author(s):  
Katarzyna Zielińska ◽  
Herman P. van Leeuwen
Keyword(s):  
Solid Phase Microextraction ◽  
Solid Phase ◽  
Aqueous Media ◽  
Aqueous Dispersion ◽  
Sio2 Nanoparticles ◽  
Sample Solution ◽  
Confocal Laser ◽  
Aqueous Sample ◽  
Free Concentration

Environmental context Organic hydrophobic compounds are present in water in low concentrations, and they can be analysed by means of a preconcentration technique called solid phase microextraction. We investigate the role of sorbing nanoparticles in the solid phase microextraction analysis of organic compounds. Our results show that nanoparticles are capable of partitioning between water and the solid phase and aggregate at the interface leading, most probably, to substantial overestimation of the original sample concentration. Abstract Solid phase microextraction (SPME) is commonly used to measure the free concentration of fairly hydrophobic substances in aqueous media on the basis of their partitioning between sample solution and a solid phase. Here we study the role of nanoparticles that may sorb the analyte in the sample medium. As an example case, the solid phase poly(dimethylsiloxane) (PDMS) is exposed to an aqueous dispersion containing silica nanoparticles with 10-nm radius. Confocal laser microscopic data show that these SiO2 nanoparticles do enter the PDMS and partition between the sample solution and solid phase. Moreover, they form aggregates at the surface of the solid phase. The overall partitioning of the SiO2 nanoparticles in the aqueous sample–PDMS system is examined and potential effects on the SPME analysis of organic analytes are indicated.

Role of temperature on colloidal behavior of gold nanoparticles dispersed in organic and aqueous media

2017 ◽  
Author(s):  
N. A. A. Bashah ◽  
E. Awel ◽  
N. Amri ◽  
R. Alrozi ◽  
N. Yaakob ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Aqueous Media ◽  
Colloidal Behavior

Photocatalytic Activity of Zirconium- and Manganese-Codoped Titania in Aqueous Media: The Role of the Metal Dopant and its Incorporation Site

ChemCatChem ◽  
2016 ◽  
Vol 8 (12) ◽  
pp. 2109-2118 ◽  
Author(s):  
Oleksii Pliekhov ◽  
Iztok Arčon ◽  
Nataša Novak Tušar ◽  
Urška Lavrenčič Štangar
Keyword(s):  
Photocatalytic Activity ◽  
Aqueous Media

The role of oxide layer formation during corrosion inhibition of mild steel in neutral aqueous media

1998 ◽  
Vol 43 (1-2) ◽  
pp. 69-75 ◽  
Author(s):  
F.H. Kármán ◽  
I. Felhösi ◽  
E. Kálman ◽  
I. Cserny ◽  
L. Kövér
Keyword(s):  
Mild Steel ◽  
Oxide Layer ◽  
Corrosion Inhibition ◽  
Aqueous Media ◽  
Layer Formation

scholarly journals Synthesis and Characterization of Chitosan/Agar/SiO2 Nano Hydrogels For Removal of Amoxicillin and of Naproxen From Pharmaceutical Contaminants

2021 ◽  
Author(s):  
Omid Moradi ◽  
Samira Mhdavi ◽  
Sajjad Sedaghat
Keyword(s):  
Aqueous Media ◽  
Environmental Pollutants ◽  
Chemical Characterization ◽  
Solution Ph ◽  
Physical And Chemical Characterization ◽  
Pharmaceutical Contaminants ◽  
Living Organisms ◽  
Physical And Chemical

Abstract Today, environmental pollutants pose a threat to human societies and all living organisms, which is why they have attracted the attention of environmental researchers. In this study, in order to remove pharmaceutical contaminants Naproxen and Amoxicillin from aqueous media with SiO2 nanoparticles based on Agar and Chitosan was investigated. The study of structural properties, physical and chemical characterization of synthesized nanocomposite was investigated by FTIR, XRD, TEM, FE-SEM, DLS and EDX analyzes. In addition, the role of parameters affecting the removal of pharmaceutical contaminants such as solution pH, contact time, contaminant concentration and temperature were studied. Nanocomposites prepared from Agar and Chitosan showed good performance in absorbing naproxen and amoxicillin. According to the studies performed to remove naproxen, the max adsorption efficiency was obtained at a concentration of 20 mg/l with an absorbent dose of 0.05 g and a pH of 8 and at an optimum temperature of 25 °C and 99% in 15 min. Also, for amoxicillin with nanocomposite prepared with an initial concentration of 20 mg/l and an adsorbent dose of 0.05 g, a time of 10 min, a temperature of 25 °C and a pH of 8, the max removal efficiency of 91.15% was obtained.

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