The Role of Hydrides in the Equilibrium of Aluminum in Aqueous Solutions

1979 ◽  
Vol 126 (2) ◽  
pp. 199-204 ◽  
Author(s):  
G. G. Perrault
Keyword(s):  
Aqueous Solutions

On the Structure of Lead(II) Complexes in Aqueous Solutions. I. Trinuclear Clusters

1995 ◽  
Vol 60 (4) ◽  
pp. 527-536 ◽  
Author(s):  
Martin Breza ◽  
Alena Manová
Keyword(s):  
Quantum Chemistry ◽  
Aqueous Solutions ◽  
Electronic Structures ◽  
Mndo Method ◽  
Model Systems ◽  
Trinuclear Clusters ◽  
The Stability ◽  
Semiempirical Mndo

Using semiempirical MNDO method of quantum chemistry the optimal geometries and corresponding electronic structures of [Pb3(OH)n]6-n model systems as well as of their hydrated [Pb3(OH)n(H2O)8-n]6-n analogues (n = 4, 5) are investigated. The most stable trinuclear lead(II) complexes present in aqueous solutions correspond to cyclo-(μ3-OH)(μ2-OH)3Pb32+, Pb(μ-OH)2Pb(μ-OH)2Pb2+, cyclo-(μ3-OH)2(μ2-OH)3Pb3+, Pb(OH)(μ-OH)2Pb(μ-OH)Pb(OH)+ and Pb(OH)(μ-OH)2Pb(μ-OH)2Pb+ systems. The key role of OH bridges (by vanishing direct Pb-Pb bonds) on the stability of individual isomers is discussed.

scholarly journals The role of Arthrobacter viscosus in the removal of Pb(II) from aqueous solutions

2017 ◽  
Vol 76 (7) ◽  
pp. 1726-1738 ◽  
Author(s):  
Raluca Maria Hlihor ◽  
Mihaela Roşca ◽  
Teresa Tavares ◽  
Maria Gavrilescu
Keyword(s):  
Aqueous Solutions ◽  
Isotherm Models ◽  
X Ray ◽  
Optimum Parameters ◽  
Living Biomass ◽  
Initial Ph ◽  
Edx Analyses ◽  
Arthrobacter Viscosus ◽  
Kinetic And Isotherm Models

The aim of this paper was to establish the optimum parameters for the biosorption of Pb(II) by dead and living Arthrobacter viscosus biomass from aqueous solution. It was found that at an initial pH of 4 and 26 °C, the dead biomass was able to remove 97% of 100 mg/L Pb(II), while the living biomass removed 96% of 100 mg/L Pb(II) at an initial pH of 6 and 28 ± 2 °C. The results were modeled using various kinetic and isotherm models so as to find out the mechanism of Pb(II) removal by A. viscosus. The modeling results indicated that Pb(II) biosorption by A. viscosus was based on a chemical reaction and that sorption occurred at the functional groups on the surface of the biomass. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX) analyses confirmed these findings. The suitability of living biomass as biosorbent in the form of a biofilm immobilized on star-shaped polyethylene supports was also demonstrated. The results suggest that the use of dead and living A. viscosus for the removal of Pb(II) from aqueous solutions is an effective alternative, considering that up to now it has only been used in the form of biofilms supported on different zeolites.

Some applications of polarography for investigation of equlibria in aqueous solutions of organic compounds

2009 ◽  
Vol 74 (11-12) ◽  
pp. 1777-1789 ◽  
Author(s):  
Petr Zuman
Keyword(s):  
Aqueous Solutions ◽  
Organic Compounds ◽  
Carbonyl Compounds ◽  
Limiting Current ◽  
Nitroso Compounds ◽  
Primary Amines ◽  
Acid Base ◽  
Fast Reactions ◽  
Half Wave

There are two possibilities how to follow equilibria of organic compounds established in aqueous solutions using polarography: for very fast reactions, information can be obtained from shifts of half-wave potentials. For slowly established equilibria, the changes in the limiting current are followed. In both cases variation of the half-wave potentials or limiting currents with concentration of a reactant, present in excess, is followed. The types of reactions, which had been followed in this way, are as follows: hydration–dehydration equilibria, additions of hydroxide ion to carbonyl and nitroso compounds, the role of slowly established acid–base equilibria involving C-acids; further also reactions involving the addition of ammonia, primary amines, hydroxylamine, and hydrazine to carbonyl compounds.

The role of electrostatic repulsion in the gelation of poly(vinyl alcohol)/borax aqueous solutions

Soft Matter ◽  
2018 ◽  
Vol 14 (32) ◽  
pp. 6767-6773 ◽  
Author(s):  
Jingjing Li ◽  
Zhijie Zhang ◽  
Xiao Cao ◽  
Yonggang Liu ◽  
Quan Chen
Keyword(s):  
Aqueous Solutions ◽  
Vinyl Alcohol ◽  
Linear Viscoelasticity ◽  
Poly Vinyl Alcohol ◽  
Electrostatic Repulsion

This study examined linear viscoelasticity of semidilute non-entangled poly(vinyl alcohol) (PVA) and borax aqueous solutions: one borax molecule dissociates into two B(OH)3 molecules and two B(OH)4− ions, and the latter can crosslink the PVA chains.

scholarly journals Dissolution of cellulose using a combination of hydroxide bases in aqueous solution

Cellulose ◽  
2019 ◽  
Vol 27 (1) ◽  
pp. 101-112 ◽  
Author(s):  
Beatrice Swensson ◽  
Anette Larsson ◽  
Merima Hasani
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Microcrystalline Cellulose ◽  
Low Temperatures ◽  
Dynamic Rheology ◽  
Organic Base ◽  
Single Base ◽  
Solvent Quality ◽  
Solvent Stability

Abstract In order to further understand the role of the cation when dissolving cellulose in aqueous solutions of hydroxide bases, different bases were combined in solution. Up to 5 wt.% of microcrystalline cellulose was dissolved using a combination of NaOH and the organic base tetramethylammonium hydroxide (TMAH) in water at low temperatures. Thermoscans of solutions containing both NaOH(aq) and TMAH(aq) indicated that cellulose interaction with TMAH seems to be favoured over NaOH. Dynamic rheology measurements of the solutions revealed that combining the two bases delayed gelation significantly when compared to cellulose dissolved in NaOH(aq) or TMAH(aq) alone. Intrinsic viscosity of cellulose in the combined NaOH- and TMAH(aq) solutions was slightly higher than that of the single-base solutions, indicating a slight increase in solvent quality. This shows that combining bases may lead to synergies that improve solvent stability without requiring the use of other additives. Graphic abstract

Photocatalytical oxidation of de-icing agents in aqueous solutions and aqueous extract of jet fuel

2001 ◽  
Vol 44 (5) ◽  
pp. 1-6 ◽  
Author(s):  
Krichevskaya M. ◽  
Malygina T. ◽  
Preis S. ◽  
Kallas J.
Keyword(s):  
Titanium Dioxide ◽  
Aqueous Solutions ◽  
Aqueous Extract ◽  
Jet Fuel ◽  
Military Bases ◽  
Oh Radicals ◽  
Oh Radical ◽  
Heavy Pollution ◽  
Shallow Ponds

Improper handling of jet fuel at abandoned military bases has resulted in heavy pollution of the soil and groundwater. Experimental research of photocatalytical oxidation (PCO) of jet fuel aqueous extract and aqueous solutions of de-icing agents was undertaken. The influence of different parameters - pH, concentration of substances to be oxidised, presence of inorganic admixtures, effect of OH• radical generators - on the PCO of solutions of de-icing agents and jet fuel aqueous extract was determined. The role of OH• radicals was found to be less important in determining the PCO rate. The PCO of organic pollutants was also investigated using a catalyst immobilised onto the surface of buoyant hollow glass micro-spheres. Attached titanium dioxide (TiO2) showed lower photocatalytical activity than when suspended in slurry, although it allows waters to be treated in simple shallow ponds without intensive stirring. The biodegradability of aqueous solutions of de-icing agents and jet fuel aqueous extract increased as PCO proceeded.

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