Electrosynthesis of Organic Amalgam from Tetraethylammonium Tetrafluoroborate in Aqueous Medium

1994 ◽  
Vol 59 (11) ◽  
pp. 2375-2382 ◽  
Author(s):  
Simon Krásenský ◽  
Marie Studničková
Keyword(s):  
Aqueous Solutions ◽  
Aqueous Medium ◽  
Anodic Oxidation ◽  
Room Temperature ◽  
Ph Value ◽  
Binary Compound ◽  
Black Precipitate ◽  
Mercury Cathode ◽  
Simultaneous Evolution

The electroreduction of neutral aqueous solutions of 0.1 - 0.5 M Et4NBF4 on a mercury cathode at room temperature at -2.8 - -2.4 V produces a black precipitate of Et4N . Hgx with simultaneous evolution of hydrogen (the pH value increases to 12). No anodic oxidation of the amalgam has been observed in the interval of 0 - 2.8 V. The composition of the precipitate, collected by filtration under nitrogen, has been determined from the decrease of Et4N+ in the solution after electrolysis and from analysis of mercury in the binary compound Et4N . Hgx. The value x = 2.9 ± 0.8 has been found.

Co-Sorption Characteristics of Zn(II) and As(V) on Mixed Fe/Al-PILCs

2013 ◽  
Vol 681 ◽  
pp. 26-30
Author(s):  
Su Yuan Wu ◽  
Hong Zheng ◽  
Peter G. Weidler ◽  
Peng Cai
Keyword(s):  
Aqueous Solutions ◽  
Langmuir Isotherm ◽  
Contact Time ◽  
Room Temperature ◽  
Ph Value ◽  
Freundlich Isotherm ◽  
Single System ◽  
Batch System ◽  
Maximum Sorption ◽  
Sorption Characteristics

Co-sorption characteristics of Zn(II) and As(V) on the mixed Fe/Al-PILCs was investigated in a batch system at room temperature. The effects of relevant parameters, such as pH value of solution, adsorbent dosage, initial Zn(II) and As(V) concentrations and contact time were examined, respectively. The results show that co-sorption capacities and co-sorption rates of Zn(II) and As(V) by Fe/Al-PILC are higher and faster than those of single Zn(II) or single As(V) by Fe/Al-PILC. Co-sorption isotherm data of Zn(II) and As(V) by Fe-Al-PILC were fitted well to Langmuir isotherm and the maximum sorption capacities of Zn(II) and As(V) on mixed Fe-Al-PILCs (Q0) are 16.98 mg/g and 16.29 mg/g, respectively, which are higher than those in single system. n>1 from Freundlich isotherm indicate that the sorption of Zn(II) and As(V) by Fe-Al-PILC is favorable. E values from D-R model indicate that the type of sorption of Zn(II) and As(V) by Fe-Al-PILC is physical. The results indicate that there is significant potential for Fe/Al-PILCs as an adsorbent material for Zn(II) and As(V) removal from aqueous solutions.

scholarly journals Size- and Surface-Dependent Solubility of Cadmium Telluride in Aqueous Solutions

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 398 ◽  
Author(s):  
Renate Zapf-Gottwick ◽  
Matthias Zorn ◽  
Jessica Nover ◽  
Michael Koch ◽  
Carolin Feifel ◽  
...  
Keyword(s):  
Particle Size ◽  
Aqueous Solutions ◽  
Diffusion Coefficients ◽  
Room Temperature ◽  
Ph Value ◽  
Leaching Behavior ◽  
Photovoltaic Modules ◽  
Chemical Treatments ◽  
Temperature Diffusion ◽  
The Stability

Due to the toxicity of cadmium (Cd) and the scarcity of telluride (Te), CdTe-based photovoltaic modules have been under discussion during the last few years. In particular, the stability of CdTe in aqueous solutions is under debate. Here we show that the stability of CdTe depends not only on the pH of water-based solutions but also on size and surface treatment of CdTe particles. We compare milled module pieces with CdTe powders of different particle size. The leaching of CdTe is conditioned by the outdiffusion of Cd and Te at the interface between CdTe particles and the aqueous solution. The smaller the particle size, the faster the leaching. Therefore, milled module pieces decompose faster than CdTe powders with relatively large grains. We observe a dependence on time t according to t0.43. The room temperature diffusion coefficients are calculated as DCd ≈ 3 × 10−17 cm2/s for Cd, and DTe ≈ 1.5 × 10−17 cm2/s for Te in pH4. The chemical instability in aqueous solutions follows thermodynamic considerations. The solution behavior of Cd and Te depends on the pH value and the redox potential of the aqueous solutions. Chemical treatments such as those used in solar cell production modify the surface of the CdTe particles and their leaching behavior.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

scholarly journals Comparison between Different Keratin-composed Biosorbents for the Removal of Heavy Metal Ions from Aqueous Solutions

2002 ◽  
Vol 20 (4) ◽  
pp. 393-416 ◽  
Author(s):  
Fawzi Banat ◽  
Sameer Al-Asheh ◽  
Dheaya‘ Al-Rousan
Keyword(s):  
Aqueous Solutions ◽  
Human Hair ◽  
Metal Ion ◽  
Ph Value ◽  
Freundlich Isotherm ◽  
Operating Conditions ◽  
Ion Uptake ◽  
Chicken Feathers ◽  
Initial Ph ◽  
Metal Ion Uptake

This study examined and compared the ability of chicken feathers, human hair and animal horns, as keratin-composed biosorbents, for the removal of Zn2+ and Cu2+ ions from single metal ion aqueous solutions under different operating conditions. The three biosorbents investigated in this study were all capable of adsorbing Zn2+ and Cu2+ ions from aqueous solutions. The biosorbent showing the highest uptake of Zn2+ and Cu2+ ions was animal horns. Chicken feathers showed a higher Cu2+ ion uptake and a lower Zn2+ ion compared to human hair. Increasing the initial concentration of Zn2+ or Cu2+ ions, or increasing the initial pH value, increased the metal ion uptake. Such uptake decreased when the temperature was raised from 25°C to 50°C for all adsorbent/metal ion combinations except for Zn2+ ion/human hair where the uptake increased with temperature. It was demonstrated that the addition of NaCl salt to the metal ion solution depressed the metal ion uptake. The Freundlich isotherm model was found to be applicable to the adsorption data for Cu2+ and Zn2+ ions.

Synthesis of 2,3-dihydroquinazolinones and quinazolin-4(3H)-ones catalyzed by graphene oxide nanosheets in an aqueous medium: “on-water” synthesis accompanied by carbocatalysis and selective C–C bond cleavage

RSC Advances ◽  
2016 ◽  
Vol 6 (27) ◽  
pp. 22320-22330 ◽  
Author(s):  
Nazia Kausar ◽  
Indranil Roy ◽  
Dipankar Chattopadhyay ◽  
Asish R. Das
Keyword(s):  
Graphene Oxide ◽  
Aqueous Medium ◽  
Room Temperature ◽  
Bond Cleavage ◽  
Graphene Oxide Nanosheets ◽  
Graphene Oxide Nanosheet

Graphene oxide nanosheet catalyzed strategies for construction of 2,3-dihydroquinazolinones and quinazolin-4(3H)-ones starting from anthranilamide and an aldehyde/ketone in aqueous medium at room temperature have been realized.

scholarly journals Supramolecular Frameworks Based on Rhenium Clusters Using the Synthons Approach

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2662
Author(s):  
Nathalie Audebrand ◽  
Antoine Demont ◽  
Racha El Osta ◽  
Yuri V. Mironov ◽  
Nikolay G. Naumov ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Crystal Structures ◽  
Ligand Exchange ◽  
Alkaline Earth ◽  
Room Temperature ◽  
Hydration Rate ◽  
Rhenium Cluster ◽  
New Compounds ◽  
Cluster Unit

The reaction of the K4[{Re6Si8}(OH)a6]·8H2O rhenium cluster salt with pyrazine (Pz) in aqueous solutions of alkaline or alkaline earth salts at 4 °C or at room temperature leads to apical ligand exchange and to the formation of five new compounds: [trans-{Re6Si8}(Pz)a2(OH)a2(H2O)a2] (1), [cis-{Re6Si8}(Pz)a2(OH)a2(H2O)a2] (2), (NO3)[cis-{Re6Si8}(Pz)a2(OH)a(H2O)a3](Pz)·3H2O (3), [Mg(H2O)6]0.5[cis-{Re6Si8}(Pz)a2(OH)a3(H2O)a]·8.5H2O (4), and K[cis-{Re6Si8}(Pz)a2(OH)a3(H2O)a]·8H2O (5). Their crystal structures are built up from trans- or cis-[{Re6Si8}(Pz)a2(OH)a4−x(H2O)ax]x−2 cluster units. The cohesions of the 3D supramolecular frameworks are based on stacking and H bonding, as well as on H3O2−bridges in the cases of (1), (2), (4), and (5) compounds, while (3) is built from stacking and H bonding only. This evidences that the nature of the synthons governing the cluster unit assembly is dependent on the hydration rate of the unit.

scholarly journals Ein Wasserstoffisotopieeffekt im CuSO4 * 5H2O

1969 ◽  
Vol 24 (10) ◽  
pp. 1502-1511
Author(s):  
Karl Heinzinger
Keyword(s):  
Water Vapor ◽  
Aqueous Solutions ◽  
Separation Factor ◽  
Room Temperature ◽  
Copper Ion ◽  
Hydrogen Isotopes ◽  
Bulk Water ◽  
Water Molecules ◽  
Hydration Water ◽  
Sulfate Solutions

Abstract There are two kinds of water in CuSO4·5H2O differing by their binding in the crystal. The oxygen of four water molecules is bonded to the copper ion, that of the fifth molecule is hydrogen bonded. It is shown that the D/H ratios of these two kinds of water differ by 5.7%, the light isotope being enriched in the water molecules coordinated with the copper ion. The results show that there is no exchange of the hydrogen isotopes during the time needed for dehydration at room temperature which takes several days. The assumption has been confirmed that the water coordinated with the copper ion leaves the crystal first on dehydration at temperatures below 50 °C. Additional measurements of the separation factor for the hydrogen isotopes between water vapor and copper sulfate solutions allow conclusions on the fractionation of the hydrogen isotopes between bulk water and hydration water in aqueous solutions.

Zinc carbonate recovery from brass melting slag

2021 ◽  
Vol 98 ◽  
pp. 14-18
Author(s):  
Thao Nguyen Thi ◽  
◽  
Nam Pham Ky ◽  
Ngoc Tran Vu Diem
Keyword(s):  
Sulfuric Acid ◽  
High Purity ◽  
Room Temperature ◽  
Ph Value ◽  
Zinc Carbonate ◽  
Leaching Solution ◽  
Optimized Conditions ◽  
Melting Slag

Brass melting slag (20.38 wt.% Zn) was leached in sulfuric acid with concentration of (50 + 80) g/l H2SO4, leaching temperature of (30 + 60) °C for (30 + 120) min. The optimized conditions for 94.16% Zn extraction from brass melting slag were found as 70 g/l H2SO4, room temperature and 90 min. The leaching solution was purified by removal of Fe through Fe(OH)3 precipitation when adding ZnO to adjust pH value of 5. The solution was continuously cemented by Zn metal at 60 °C for 60 min to obtain Cu metal with high purity of 99 wt.% Cu. The purified solution with 37.64 g/l Zn was modified by Na2C03 to have pH value of about 6 and precipitation of ZnC03 (94.14 %).

scholarly journals Evaluation of temporal, seasonal and geographic stability of the molluscicidal property of Euphorbia splendens latex

1992 ◽  
Vol 34 (3) ◽  
pp. 183-191 ◽  
Author(s):  
Virginia Torres Schall ◽  
Mauricio Carvalho de Vasconcellos ◽  
Ana Luiza Villaça-Coelho ◽  
Fátima Eliana Ferreira-Lopes ◽  
Ivonise Paz da Silva
Keyword(s):  
Aqueous Solutions ◽  
Laboratory Tests ◽  
Large Scale ◽  
Room Temperature ◽  
Tropical Climate ◽  
Wide Distribution ◽  
Promising Material ◽  
Active Principle ◽  
Reference Substance ◽  
Belo Horizonte

Laboratory tests with aqueous solutions of Euphorbia splendens var. hislopii latex have demonstrated seasonal stability of the molluscicidal principle, with LD90 values of 1.14 ppm (spring), 1.02 ppm (fall), 1.09 ppm (winter), and 1.07 ppm (summer) that have been determined against Biomphalaria tenagophila in the field. Assays on latex collected in Belo Horizonte and Recife yielded LD90 values similar to those obtained with the reference substance collected in Rio de Janeiro (Ilha do Governador), demonstrating geographic stability of the molluscicidal effect. The molluscicidal action of aqueous dilutions of the latex in natura, centrifuged (precipitate) and lyophilized, was stable for up to 124 days at room temperature (in natura) and for up to 736 days in a common refrigerator at 10 to 12ºC (lyophilized product). A 5.0 ppm solution is 100% lethal for snails up to 13 days after preparation, the effect being gradually lost to almost total inactivity by the 30th day. This observation indicated that the active principle is instable. These properties together with the wide distribution of the plant, its resistance and adaptation to the tropical climate, its easy cultivation and the easy obtention of latex and preparation of the molluscicidal solution, make this a promising material for large-scale use in the control of schistosomiasis

pH‐Transformed ZnO‐NPs /NaPTS: The First Room‐Temperature Brisk Synthesis of Flavanones in Aqueous Medium

2018 ◽  
Vol 3 (46) ◽  
pp. 13197-13206 ◽  
Author(s):  
Bipin Shinde ◽  
Santosh B. Kamble ◽  
Dattaprasad M. Pore ◽  
Prasad Gosavi ◽  
Amol Gaikwad ◽  
...  
Keyword(s):  
Aqueous Medium ◽  
Room Temperature ◽  
Zno Nps
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