scholarly journals Dissolution and Solubility of the (BaxSr1-x)HAsO4·H2O Solid Solution in Aqueous Solution at 25°C and pH 2

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Xuehong Zhang ◽  
Yinian Zhu ◽  
Caichun Wei ◽  
Zongqiang Zhu ◽  
Zongning Li
Keyword(s):  
Solid Solution ◽  
Aqueous Solution ◽  
Solubility Product ◽  
Enthalpy Of Mixing ◽  
Saturation Curve ◽  
Free Energies ◽  
Batch Experiments ◽  
Dissolution Experiment ◽  
Barium Concentration ◽  
Solubility Products

Six different members of the (BaxSr1-x)HAsO4·H2O solid solution were prepared and characterized, and then dissolution of the synthetic solids was studied at 25°C and pH 2 in a series of batch experiments for 4320 h. With the increase in the Ba/(Ba+Sr) mole fraction of the solids, the aqueous pH decreased and the aqueous barium concentration increased. The aqueous strontium and arsenic concentrations had the highest values atBa/(Ba+Sr)=0.21. The solubility products for BaHAsO4·H2O and SrHAsO4·H2O were calculated to be10-5.52and10-4.62, respectively. The corresponding free energies of formation were determined to be −1543.99±0.18 kJ/mol and −1537.94±0.02 kJ/mol. The solid solution had a minimum solubility product of10-5.61atBa/(Ba+Sr)=0.82. The Guggenheim coefficients were determined to beao=1.55anda1=-4.35. The Lippmann diagram was a typical Lippmann diagram for a nonideal solid solution with a negative enthalpy of mixing. The system shows an “alyotropic” minimum at the aqueousBa/(Ba+Sr)activity fraction of 0.87 where thesolutusandsoliduscurves meet. At the end of the dissolution experiment, the dissolution followed the saturation curve for the pure endmember BaHAsO4·H2O and approached the intersection with the minimum stoichiometric saturation curve on the Lippmann diagram.

An ideal solid solution model for calculating solubility of clay minerals

Clay Minerals ◽  
1981 ◽  
Vol 16 (4) ◽  
pp. 361-373 ◽  
Author(s):  
Y. Tardy ◽  
B. Fritz
Keyword(s):  
Solid Solution ◽  
Clay Minerals ◽  
Chemical Evolution ◽  
Solid Solutions ◽  
Natural Water ◽  
Free Energies ◽  
Natural Clay ◽  
Data Set ◽  
Solubility Products ◽  
End Members

AbstractA method for estimating Gibbs free energies and stabilities of clay minerals is proposed for use with computer programs aimed at calculating the chemical evolution of natural water-rock systems. This is based on (i) a model for ideal solid solutions of a large number of end-member compositions and (ii) a data set of estimated solubility products from 36 end-members. The application of the method to the production of experimental or natural clay stabilities is discussed.

scholarly journals Dissolution and solubility of the arsenate - phosphate hydroxylapatite solid solution [Ca5(PxAs1 - xO4)3(OH)] at 25°C

2011 ◽  
Vol 8 (2) ◽  
pp. 133 ◽  
Author(s):  
Xuehong Zhang ◽  
Yinian Zhu ◽  
Honghu Zeng ◽  
Dunqiu Wang ◽  
Jie Liu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Aqueous Solution ◽  
Steady State ◽  
Mole Fraction ◽  
Large Family ◽  
Batch Experiments ◽  
Aqueous Environments ◽  
Phosphate Species ◽  
Peak Value

Environmental contextApatites form a large family of minerals and compounds that can incorporate a variety of ions, including arsenate that can substitute for phosphate. Apatites may therefore control the concentration of arsenic in some aqueous environments. This manuscript describes the synthesis and characterisation of the arsenate–phosphate hydroxylapatite solid solution and the solid solution–aqueous solution interaction. Abstract Nine different members of the arsenate–phosphate hydroxylapatite solid solution [Ca5(PxAs1–xO4)3(OH)] were prepared and characterised by various techniques, and then dissolution of the synthetic solids was studied at 25°C and pH 2 in a series of batch experiments. The concentrations of aqueous arsenate species increased rapidly at the beginning of the dissolution and reached a steady-state after 480 h. The concentrations of aqueous phosphate species increased very fast initially and reached a peak value within the first hour of dissolution and then declined slowly with time and remained constant after 240–360 h. The solubility of the Ca5(PxAs1–xO4)3(OH) solid solution increased and its stability decreased with an increase in the mole fraction of Ca5(AsO4)3(OH). The dissolution followed or slightly overshot the Lippmann solutus curve, then approached the solutus curve. The Ca5(AsO4)3(OH)-poor solid solution was in equilibrium with the arsenate-rich aqueous solution.

scholarly journals Dissolution, Solubility, and Stability of the Basic Ferric Sulfate-Arsenates [Fe(SO4)x(AsO4)y(OH)z·nH2O] at 25–45°C and pH 2–10

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zongqiang Zhu ◽  
Hongqu Yang ◽  
Jie Liu ◽  
Yinian Zhu ◽  
Shen Tang ◽  
...  
Keyword(s):  
Ferric Sulfate ◽  
Iron Sulfate ◽  
Acidic Environment ◽  
Free Energies ◽  
Crystal Surfaces ◽  
Dissolution Experiment ◽  
Ion Activity ◽  
Initial Ph ◽  
Solubility Products ◽  
Ion Activity Products

Basic ferric sulfate-arsenates [FeSAsOH, Fe(SO4)x(AsO4)y(OH)z·nH2O] were prepared and characterized to study their potential fixation of arsenic in the oxidizing and acidic environment through a dissolution for 330d. The synthetic solids were well-shaped monoclinic prismatic crystals. For the dissolution of the sample FeSAsOH–1 [Fe(SO4)0.27(AsO4)0.73 (OH)0.27·0.26H2O] at 25–45°C and initial pH 2, all constituents preferred to be dissolved in the order of AsO43− > SO42− > Fe3+ in 1–3 h, in the order of SO42− > AsO43− > Fe3+ from 1–3 h to 12–24 h, and finally in the order of SO42− > Fe3+ > AsO43−. The released iron, sulfate, and arsenate existed dominantly as Fe3+/Fe(OH)2+/FeSO4+, HSO4−/SO42−/FeSO4+, and H3AsO40/H2AsO4−, respectively. The higher initial pHs (6 and 10) could obviously inhibit the release of Fe3+ from solid into solution, and the solid components were released in the order of SO42− > AsO43− > Fe3+. The crystal tops were first dissolved, and the crystal surfaces were gradually smoothed/rounded until all edges and corners disappeared. The dissociations were restricted by the Fe-O(H) breakdown in the FeO6 octahedra and obstructed by the OH− and AsO4 tetrahedra outliers; the lowest concentration of the dissolved arsenic was 0.045 mg/L. Based on the dissolution experiment at 25°C and pH 2, the solubility products (Ksp) for the basic ferric sulfate-arsenate [Fe(SO4)0.27(AsO4)0.73 (OH)0.27·0.26H2O], which are equal to the ion activity products (logˍIAP) at equilibrium, were calculated to be -23.04 ± 0.01 with the resulting Gibbs free energies of formation (ΔGfo) of −914.06 ± 0.03 kJ/mol.

2-Deoxyribose Radicals in the Gas Phase and Aqueous Solution. Transient Intermediates of Hydrogen Atom Abstraction from 2-Deoxyribofuranose

2005 ◽  
Vol 70 (11) ◽  
pp. 1769-1786 ◽  
Author(s):  
Luc A. Vannier ◽  
Chunxiang Yao ◽  
František Tureček
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Atom ◽  
Gas Phase ◽  
Computational Study ◽  
Hydrogen Atom Abstraction ◽  
Oh Radical ◽  
Free Energies ◽  
Intramolecular Hydrogen ◽  
Solvation Free Energies ◽  
Transient Intermediates

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.

A QM/MM study combined with the theory of energy representation: Solvation free energies for anti/syn acetic acids in aqueous solution

2006 ◽  
Vol 419 (1-3) ◽  
pp. 240-244 ◽  
Author(s):  
Takumi Hori ◽  
Hideaki Takahashi ◽  
Masayoshi Nakano ◽  
Tomoshige Nitta ◽  
Weitao Yang
Keyword(s):  
Aqueous Solution ◽  
Free Energies ◽  
Solvation Free Energies ◽  
Acetic Acids

Solution Properties of Tetraalkylammonium Halide and Alkali-Metal Halide Ion Pairs. The Relationship Between Dissociation Constants and Solubility Products

1987 ◽  
Vol 40 (7) ◽  
pp. 1201 ◽  
Author(s):  
W Mizerski ◽  
MK Kalinowski
Keyword(s):  
Alkali Metal ◽  
Solubility Product ◽  
Dissociation Constants ◽  
Ion Pairs ◽  
Empirical Relation ◽  
Alkali Metal Halide ◽  
Alkali Metal Cations ◽  
Solubility Products ◽  
The Relationship ◽  
Dissociation Constant Kd

An empirical relation describing the effect of solvent on the dissociation constant ( Kd ) of ion pairs is described. An equation of the form pKd = apKso + bD-1 + c ( Kso and D stand for the solubility product of a given salt and for the electric permittivity of a solvent, respectively) has been tested with 13 sets of experimental data for salts containing tetraalkylammonium and alkali-metal cations. A successful correlation was obtained in 100% of the cases considered.

scholarly journals Removal of Chromium from Aqueous Solution Using Modified Pomegranate Peel:Mechanistic and Thermodynamic Studies

2009 ◽  
Vol 6 (s1) ◽  
pp. S153-S158 ◽  
Author(s):  
Tariq S. Najim ◽  
Suhad A. Yassin
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Aqueous Solution ◽  
Adsorption Process ◽  
Batch Process ◽  
The Other ◽  
Water Molecules ◽  
Pomegranate Peel ◽  
Solution Interface ◽  
Adsorbent Surface

Modified pomegranate peel (MPGP) and formaldehyde modified pomegranate peel (FMPGP) were prepared and used as adsorbent for removal of Cr(VI) ions from aqueous solution using batch process. The temperature variation study of adsorption on both adsorbents revealed that the adsorption process is endothermic, from the positive values of ∆H˚. These values lie in the range of physisorption. The negative values of ∆G˚ show the adsorption is favorable and spontaneous. On the other hand, these negative values increases with increase in temperature on both adsorbents, which indicate that the adsorption is preferable at higher temperatures. ∆S˚ values showed that the process is accompanied by increase in disorder and randomness at the solid solution interface due to the reorientation of water molecules and Cr(VI) ions around the adsorbent surface. The endothermic nature of the adsorption was also confirmed from the positive values of activation energy, Ea, the low values of Ea confirm the physisorption mechanism of adsorption. The sticking probability, S*, of Cr(VI) ion on surface of both adsorbents showed that the adsorption is preferable due to low values of S*(0< S*< 1 ), but S*values are lower for FMPGP indicating that the adsorption on FMPGP is more preferable .

scholarly journals BIOSORPTION OF METHYLENE BLUE BY WASTE APRICOT SHELLS FROM FOOD INDUSTRY

2018 ◽  
Vol 4 (7) ◽  
Author(s):  
Tatjana Šoštarić ◽  
Marija Petrović ◽  
Jelena Milojković ◽  
Jelena Petrović ◽  
Marija Stanojević ◽  
...  
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Methylene Blue ◽  
Food Industry ◽  
Fruit Juice ◽  
Waste Waters ◽  
Batch Experiments ◽  
Biosorption Capacity ◽  
Biosorption Process ◽  
Monolayer Adsorption

In this paper, the removal of methylene blue (MB) from aqueous solution by biosorption ontoapricot shellshas been investigated through batch experiments. Apricot shells were chosen as alocally available and abundant waste from fruit juice industry. Methylene blue is common pollutantof waste waters from textile industry.The influence of initial MB concentration on biosorption process has been studied. Theexperimental data have been analysed using Langmuir and Freundlichisotherm models. TheLangmuir model better fits to experimental data, which explain monolayer adsorption. Maximumbiosorption capacity is 24,31 mg/g. A comparison of the biosorption capacity of waste apricot shellswith biosorption capacities of similar adsorbents previously investigated indicates that apricotshells could be a promising biosorbent for removal of MB from aqueous solution.

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