scholarly journals Copper Chloro-Complexes Concentrated Solutions: An Electrochemical Study

Batteries ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 83 ◽  
Author(s):  
Giampaolo Lacarbonara ◽  
Luigi Faggiano ◽  
Stefania Porcu ◽  
Pier Carlo Ricci ◽  
Stefania Rapino ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Calcium Chloride ◽  
Orthophosphoric Acid ◽  
Concentrated Solutions ◽  
Chloro Complexes ◽  
Redox Flow Batteries ◽  
Phosphate Ions ◽  
Rich Solution ◽  
The Stability ◽  
Basic Studies

Basic studies on concentrated solutions are becoming more and more important due to the practical industrial and geological applications. The use in redox flow batteries is one of the most important applications of these solutions. Specifically, in this paper we investigated high-concentrated copper chloro-complexes solutions with different additives. The concentration of ligands and additives affects the physicochemical and electrochemical properties of 2 M solutions of Cu(I) and Cu(II). Solutions with calcium chloride and HCl as Cl− source were investigated with Cu:Cl ratios of 1:5 and 1:7, the 1:5 Cu:Cl ratio being the best performing. The substitution of calcium chloride with ammonium chloride increased the conductivity. However, while the effect on the positive electrode process was not very evident, the reversibility of the copper deposition–stripping process was greatly improved. Orthophosphoric acid could be a viable additive to decrease the complexation of calcium with chloride anions and to improve the stability of Cu(II) chloro-complexes. Absorption spectroscopy demonstrated that phosphate ions do not coordinate copper(II) but lead to a shift in the distribution of copper chloro-complexes toward more coordinated species. Electrochemically, the increased availability of chloride anions in solution stabilized the Cu(II)-rich solution and led to increased reversibility of the Cu(II)/Cu(I) redox process.

scholarly journals Anti-Streptococcus mutans and anti-biofilm activities of dextranase and its encapsulation in alginate beads for application in toothpaste

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10165
Author(s):  
Nucharee Juntarachot ◽  
Sasithorn Sirilun ◽  
Duangporn Kantachote ◽  
Phakkharawat Sittiprapaporn ◽  
Piyachat Tongpong ◽  
...  
Keyword(s):  
Sodium Alginate ◽  
Calcium Chloride ◽  
Streptococcus Mutans ◽  
Dental Plaque ◽  
Biofilm Formation ◽  
Alginate Beads ◽  
Oral Diseases ◽  
Sensory Test ◽  
Alginate Concentration ◽  
The Stability

Background The accumulation of plaque causes oral diseases. Dental plaque is formed on teeth surfaces by oral bacterial pathogens, particularly Streptococcus mutans, in the oral cavity. Dextranase is one of the enzymes involved in antiplaque accumulation as it can prevent dental caries by the degradation of dextran, which is a component of plaque biofilm. This led to the idea of creating toothpaste containing dextranase for preventing oral diseases. However, the dextranase enzyme must be stable in the product; therefore, encapsulation is an attractive way to increase the stability of this enzyme. Methods The activity of food-grade fungal dextranase was measured on the basis of increasing ratio of reducing sugar concentration, determined by the reaction with 3, 5-dinitrosalicylic acid reagent. The efficiency of the dextranase enzyme was investigated based on its minimal inhibitory concentration (MIC) against biofilm formation by S. mutans ATCC 25175. Box-Behnken design (BBD) was used to study the three factors affecting encapsulation: pH, calcium chloride concentration, and sodium alginate concentration. Encapsulation efficiency (% EE) and the activity of dextranase enzyme trapped in alginate beads were determined. Then, the encapsulated dextranase in alginate beads was added to toothpaste base, and the stability of the enzyme was examined. Finally, sensory test and safety evaluation of toothpaste containing encapsulated dextranase were done. Results The highest activity of the dextranase enzyme was 4401.71 unit/g at a pH of 6 and 37 °C. The dextranase at its MIC (4.5 unit/g) showed strong inhibition against the growth of S. mutans. This enzyme at 1/2 MIC also showed a remarkable decrease in biofilm formation by S. mutans. The most effective condition of dextranase encapsulation was at a pH of 7, 20% w/v calcium chloride and 0.85% w/v sodium alginate. Toothpaste containing encapsulated dextranase alginate beads produced under suitable condition was stable after 3 months of storage, while the sensory test of the product was accepted at level 3 (like slightly), and it was safe. Conclusion This research achieved an alternative health product for oral care by formulating toothpaste with dextranase encapsulated in effective alginate beads to act against cariogenic bacteria, like S. mutants, by preventing dental plaque.

Quest for Organic Active Materials for Redox Flow Batteries: 2,3-Diaza-anthraquinones and Their Electrochemical Properties

2018 ◽  
Vol 30 (3) ◽  
pp. 762-774 ◽  
Author(s):  
Jonas D. Hofmann ◽  
Felix L. Pfanschilling ◽  
Nastaran Krawczyk ◽  
Peter Geigle ◽  
Longcheng Hong ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Active Materials ◽  
Redox Flow Batteries ◽  
Flow Batteries

Speciation of cadmium in soil solutions of saline/sodic soils and relationship with cadmium concentrations in potato tubers (Solanum tuberosum L.)

Soil Research ◽  
1997 ◽  
Vol 35 (1) ◽  
pp. 183 ◽  
Author(s):  
M. J. McLaughlin ◽  
K. G. Tiller ◽  
M. K. Smart
Keyword(s):  
Soil Solution ◽  
Soil Ph ◽  
Solanum Tuberosum L ◽  
Alkaline Soil ◽  
Sodic Soils ◽  
Chloro Complexes ◽  
Soil Solutions ◽  
High Concentrations ◽  
The Stability ◽  
Saline Solutions

Fifty commercial potato crops and associated soils were sampled. Soil solutions were extracted from rewetted soils by centrifugation, and solution composition was related to Cd concentrations in tubers. Soils were also extracted with 0·01 M Ca(NO3)2 and 0·01 M CaCl2 solutions, and Cd2+ activities in the extracts were calculated by difference using the stability constants for formation of CdCl2-nn species. The soils had saline solutions (>4 dS/m), and Cl- and SO2-4 in solution markedly affected the speciation of Cd in soil solution, with chloro-complexes, in particular, dominating. While low soil pH was associated with high (>25 nM) concentrations of Cd in soil solution, chloro-complexation also led to high concentrations of Cd in solution, even at neutral to alkaline soil pH values. Tuber Cd concentrations were not related to activities of Cd2+ in soil solution or to activities in dilute salt extracts of soil. Tuber Cd concentrations were related to the degree of chloro-complexation of Cd in solution. The relationship of tuber Cd concentrations to chloro-complexation in soil solution suggests that Cd species other than the free Cd2+ ion are involved in the transport through soil and uptake of Cd by plants.

In Situ HREm of Reactions at Interfaces

1997 ◽  
Vol 3 (S2) ◽  
pp. 621-622 ◽  
Author(s):  
R. Sinclair ◽  
T. Itoh ◽  
H. J. Lee ◽  
K. W. Kwon
Keyword(s):  
Chemical Interaction ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Interface Chemistry ◽  
Amorphous Phases ◽  
Resolution Electron ◽  
Analogous Manner ◽  
The Stability ◽  
Basic Studies

Reactions at solid-solid interfaces are important both scientifically and technologically. Firstly, there is quite a wide variety of possibilities. Materials can react with one another, forming equilibrium, meta-stable or even amorphous phases. The interface can provide a means to promote phase reactions kinetically, in an analogous manner to catalysis. Even when the materials are mutually compatible chemically, the interface topography and atomic structure can evolve over the course of time. From the practical point-of-view, changes in the interface chemistry and structure can profoundly alter the physical properties. This is especially notable in thin film technology, whereby the interfaces constitute a signigicant proportion of the whole device. In this article, contributions to understanding this field are illustrated through application of in situ and high-resolution electron microscopy (HREM).Basic studies of metal-semicoductor interfacial reactions have been successfully carried out for a number of years. of increasing importance in microelectronics is the stability of layers which prevent chemical interaction, namely the diffusion barriers.

A comparison between the mode of sction of organic matter and synthetic polymers in stabilizing soil crumbs

1956 ◽  
Vol 47 (3) ◽  
pp. 350-353 ◽  
Author(s):  
W. W. Emerson
Keyword(s):  
Organic Matter ◽  
Polyvinyl Alcohol ◽  
Natural Soil ◽  
Amino Groups ◽  
Ionic Polymer ◽  
Phosphate Ions ◽  
Before And After ◽  
The Stability ◽  
Method Of Extraction ◽  
Neutral Sodium

Synthetic soil crumbs stabilized by the addition of small quantities of a polymer, and natural soil crumbs from old grassland, have been extracted with neutral sodium pyrophosphate and alkali and the strengths of the crumbs compared before and after extraction, using the sodium saturation technique. Three polymers were used: polyvinyl alcohol (a non-ionic polymer), sodium alginate, and a vinyl acetate-maleic anhydride co-polymer (Vama), the latter both carboxylated polymers. Pyrophosphate was able to displace the carboxylated polymers from the synthetic crumbs, but not the stabilizing fraction of the organic matter from the grassland crumbs. 0·5N-NaOH produced a much greater reduction on the strength of the alginate treated crumbs compared with Vama crumbs, which is attributed to the weaker hydrogen bonds formed by the former. Prolonged leaching with alkali removed a considerable part of the stabilizing organic matter in the grassland crumbs. Neither method of extraction affected the stability of the polyvinyl alcohol crumbs.It is concluded that the grassland crumbs are stabilized by the formation of inter-lamellar complexes with the clay in the crumbs, and probably that the substance forming the complexes is a polymer and contains amino-groups.Evidence is also given that phosphate ions and the carboxylated polymers are attached in the same manner to the edges of the clay crystals.

Rheological properties of concentrated solutions of cellulose and its mixtures with other polymers in orthophosphoric acid

2011 ◽  
Vol 84 (3) ◽  
pp. 594-598 ◽  
Author(s):  
D. D. Grinshpan ◽  
A. N. Gonchar ◽  
N. G. Tsygankova ◽  
S. E. Makarevich ◽  
T. A. Savitskaya ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Orthophosphoric Acid ◽  
Concentrated Solutions

POLYCONDENSED ANIONS OF THE TRANSITION METALS: LIGHT SCATTERING AND ULTRACENTRIFUGATION WITH SCHLIEREN AND INTERFERENCE OPTICS OF ALKALINE NIOBIUM (V) SOLUTIONS

1964 ◽  
Vol 42 (4) ◽  
pp. 731-743 ◽  
Author(s):  
Wilfred H. Nelson ◽  
R. Stuart Tobias
Keyword(s):  
Light Scattering ◽  
Experimental Methods ◽  
Degree Of Polymerization ◽  
Potassium Ions ◽  
High Symmetry ◽  
Concentrated Solutions ◽  
Solvent Water ◽  
A Value ◽  
The Stability ◽  
Equilibrium Ultracentrifugation

Alkaline aqueous niobium(V) solutions prepared by dissolving the salt K14Nb12O37•27H2O were studied by means of light scattering and by equilibrium ultracentrifugation by using both schlieren and interference optics. All three experimental methods indicate that the degree of polymerization of the polycondensed niobate anion is no less than 5 and probably has the value 6. The centrifugation data indicate that only one polycondensed species exists in the solutions. The effective charge of the niobate anion appears to be reduced appreciably by the binding of potassium ions to a value of no greater than −2. The behavior of the solutions is very similar to that observed previously with alkaline tantalum(V) solutions, and it appears very likely that the hexameric anion [HNb6O19]−7 found in niobate crystals also exists in aqueous solutions. The niobate is slightly protonated in comparison to the analogous tantalate. The stability of highly concentrated solutions containing this large polycondensed species is probably the result of the existence of a poly-ion with high symmetry which interacts only weakly with the solvent, water.

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