scholarly journals Dissolution and Solubility of the Synthetic Natroalunite and the Arsenic-Incorporated Natroalunite at pH of 2.00–5.60 and 25–45°C

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Yinian Zhu ◽  
Huiling Xuan ◽  
Yanpeng Liang ◽  
Qiming Yan ◽  
Zongqiang Zhu ◽  
...  
Keyword(s):  
Environmental Science ◽  
Pure Water ◽  
Thermodynamic Quantities ◽  
Free Energies ◽  
Solution Ph ◽  
Ph Variation ◽  
Initial Ph ◽  
Solubility Products ◽  
Living Organisms ◽  
Arsenic Incorporation

Arsenic is very harmful to most living organisms. The solubility data of As-containing compounds are significant in geoscience and environmental science. The arsenic-incorporated natroalunite precipitation has been proposed to eliminate arsenic from water, both for industrial practice and remediation of polluted areas. Unfortunately, only few works have been made on partial arsenic incorporation in natroalunite and the thermodynamic data for natroalunite and arsenic-incorporated natroalunite now are still lacking. Moreover, the dissolution mechanisms of arsenic-incorporated natroalunites have never been studied. In the present work, the dissolution of the synthetic natroalunite [Na0.93(H3O)0.61Al2.82(SO4)2(OH)6] and the synthetic arsenic-incorporated natroalunite [Na0.88(H3O)2.44Al2.35(AsO4)0.38(SO4)1.62(OH)6] at 25°C, 35°C, and 45°C was experimentally examined in HNO3 solution (pH of 2.00 and 4.00) and pure water. The characterizations confirmed that the solids showed no recognizable change after dissolution. All dissolutions underwent a pH variation, which was caused by a great depleting of H3O+/OH− ions, typically at the reaction beginning. The dissolution in H3O+ medium proved to be near-stoichiometric within the short beginning period, and the dissolved Na+, Al3+, SO42−, and AsO43− concentrations were stoichiometric according to the initial solids and then appeared to be nonstoichiometric with the Na/SO4 mole ratios higher and the Al/SO4 and AsO4/SO4 mole ratios lower than the stoichiometry until the experimental end, indicating that the components were released from solid to solution preferentially after the following order: Na+ (H3O+) > SO42− > AsO43− > Al3+. From the experimental results under the condition of initial pH 2.00 and 25°C, the solubility products [Ksp] and the Gibbs free energies of formation [ΔGf°] were calculated to be 10−81.02±0.33∼10−81.04±0.27 and −4713 ± 2 to −4714 ± 1 kJ/mol for the natroalunite and 10−92.30±0.30∼10−92.41±0.37 and −5078 ± 2 to −5079 ± 2 kJ/mol for the arsenic-incorporated natroalunite, respectively. The thermodynamic quantities, ΔG°, ΔH°, ΔS°, and ΔCp°, were determined to be 462303.43 J/K·mol, 122466.83 J/mol, −1140.39 J/K·mol, and 4280.13 J/K·mol for the natroalunite dissolution reaction at initial pH 2.00 and 25°C and to be 526925.48 J/K·mol, 159674.76 J/mol, −1232.38 J/K·mol, and 1061.12 J/K·mol for the dissolution of the arsenic-incorporated natroalunite at initial pH 2.00 and 25°C, respectively.

scholarly journals Characterization, Dissolution, and Solubility of Zn-Substituted Hydroxylapatites [(ZnxCa1−x)5(PO4)3OH] at 25°C

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Xin Zhao ◽  
Yinian Zhu ◽  
Zongqiang Zhu ◽  
Yanpeng Liang ◽  
Yanlong Niu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Lattice Parameter ◽  
Batch Experiment ◽  
Molar Ratio ◽  
Final Solution ◽  
Free Energies ◽  
Solution Ph ◽  
Initial Ph ◽  
Zinc Concentrations ◽  
The Mean

A series of Zn-substituted hydroxylapatites [(ZnxCa1−x)5(PO4)3OH, Zn-Ca-HA] with the Zn/(Zn + Ca) molar ratio (XZn) of 0~0.16 was prepared and characterized, and then the dissolution of the synthesized solids in aqueous solution was investigated by batch experiment. The results indicated that the aqueous zinc, calcium, and phosphate concentrations greatly depended on the Zn/(Zn + Ca) molar ratio of the Zn-Ca-HA solids (XZn). For the Zn-Ca-HA dissolution at 25°C with an initial pH of 2.00, the final solution pH increased, while the final solution calcium and phosphate concentrations decreased with the increasing XZn. The final solution zinc concentrations increased with the increasing XZn when XZn≤0.08 and decreased with the increasing XZn when XZn = 0.08~0.16. The mean Ksp values for (ZnxCa1−x)5(PO4)3OH at 25°C decreased from 10−57.75 to 10−58.59 with the increasing XZn from 0.00 to 0.08 and then increased from 10–58.59 to 10–56.63 with the increasing XZn from 0.08 to 0.16. This tendency was consistent with the dependency of the lattice parameter a on XZn. The corresponding free energies of formation (ΔGfo) increased lineally from −6310.45 kJ/mol to −5979.39 kJ/mol with the increasing XZn from 0.00 to 0.16.

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.

scholarly journals Dissolution and Solubility Product of Cd-Fluorapatite [Cd5(PO4)3F] at pH of 2–9 and 25–45°C

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Ju Lin ◽  
Zongqiang Zhu ◽  
Yinian Zhu ◽  
Huili Liu ◽  
Lihao Zhang ◽  
...  
Keyword(s):  
Solubility Product ◽  
Pure Water ◽  
Solution Ph ◽  
Cadmium Ions ◽  
Molar Ratios ◽  
Free Energy Of Formation ◽  
Initial Ph ◽  
Naoh Solution ◽  
Total Dissolution ◽  
Energy Of Formation

Dissolution of the synthetic cadmium fluorapatite [Cd5(PO4)3F] at 25°C, 35°C, and 45°C was experimentally examined in HNO3 solution, pure water, and NaOH solution. The characterization results confirmed that the cadmium fluorapatite nanorods used in the experiments showed no obvious variation after dissolution. During the dissolution of Cd5(PO4)3F in HNO3 solution (pH = 2) at 25°C, the fluoride, phosphate, and cadmium ions were rapidly released from solid to solution, and their aqueous concentrations had reached the highest values after dissolution for <1 h, 1440 h, and 2880 h, respectively. After that, the total dissolution rates declined slowly though the solution Cd/P molar ratios increased incessantly from 1.55∼1.67 to 3.18∼3.22. The solubility product for Cd5(PO4)3F (Ksp) was determined to be 10−60.03 (10−59.74∼10−60.46) at 25°C, 10−60.38 (10−60.32∼10−60.48) at 35°C, and 10−60.45 (10−60.33∼10−60.63) at 45°C. Based on the log Ksp values obtained at an initial pH of 2 and 25°C, the Gibbs free energy of formation for Cd5(PO4)3F (ΔGf0) was calculated to be −4065.76 kJ/mol (−4064.11∼−4068.23 kJ/mol). The thermodynamic parameters for the dissolution process were computed to be 342515.78 J/K·mol, −85088.80 J/mol, −1434.91 J/K·mol, and 2339.50 J/K·mol for ΔG0, ΔH0, ΔS0, and ΔCp0, correspondingly.

Adsorption of 4-Chloro-2,5-Dimethoxy Nitrobenzene by Activated Pyrolytic Char from Pine Sawdust

2014 ◽  
Vol 884-885 ◽  
pp. 190-194
Author(s):  
Wei Xiao ◽  
Ran Di Zhang ◽  
Yu Bing Song ◽  
Run Ping Han ◽  
Yan Qiang Li
Keyword(s):  
Solution Temperature ◽  
Isotherm Models ◽  
Dihydrogen Phosphate ◽  
Solution Ph ◽  
Pine Sawdust ◽  
Major Mechanism ◽  
Nacl Concentration ◽  
Initial Ph ◽  
Higher Temperature ◽  
Pyrolytic Char

The adsorption studies of 4-chloro-2,5-dimethoxy nitrobenzene (CDNB) from aqueous solution on pyrolytic char activated by ammonium dihydrogen phosphate from pine sawdust have been performed. Several experimental parameters like initial pH, NaCl concentration, contact time solution temperature were evaluated. Solution pH within 2-7 is favor of adsorption and it is advantage of adsorption at higher temperature. Langmuir, Freundlich and Temkin isotherm models were used to fit the experimental data and Temkin model was better. The adsorption capacity was up to 33.8 mg·g1at 323 K. The process is spontaneous and endothermic and physical action is major mechanism.

scholarly journals A Theoretical and Experimental Study of Electrochemical pH Control at Gold Interdigitated Microband Arrays

2021 ◽  
Author(s):  
Bernardo Patella ◽  
Robert Daly ◽  
Ian Seymour ◽  
Pierre Lovera ◽  
James Rohan ◽  
...  
Keyword(s):  
Electrode Array ◽  
Ph Control ◽  
Reduction Peak ◽  
Solution Ph ◽  
Ph Indicator ◽  
Ph Change ◽  
Initial Ph ◽  
The Impact ◽  
Strong Acids

In electroanalysis, solution pH is a critical parameter that often needs to be adjusted and controlled for the detection of particular analytes. This is most commonly performed by the addition of chemicals, such as strong acids or bases. Electrochemical in-situ pH control offers the possibility for the local adjustment of pH at the point of detection, without additional reagents. FEA simulations have been performed to guide experimental design for both electroanalysis and in-situ control of solution pH. No previous model exists that describes the generation of protons at an interdigitated electrode array in buffered solution with one comb acting as a protonator, and the other as the sensor. In this work, FEA models are developed to provide insight into the optimum conditions necessary for electrochemical pH control. The magnitude of applied galvanostatic current has a direct relation to the flux of protons generated and subsequent change in pH. Increasing the separation between the electrodes increases the time taken for protons to diffuse across the gap. The final pH achieved at both, protonators and sensor electrodes, after 1 second, was shown to be largely uninfluenced by the initial pH of the solution. The impact of buffer concentration was modelled and investigated. In practice, the pH at the electrode surface was probed by means of cyclic voltammetry, i.e., by cycling a gold electrode in solution and identifying the potential of the gold oxide reduction peak. A pH indicator, methyl red, was used to visualise the solution pH change at the electrodes, comparing well with the model’s prediction

scholarly journals Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one : emerging munitions compounds

2021 ◽  
Author(s):  
Julie Becher ◽  
Samuel Beal ◽  
Susan Taylor ◽  
Katerina Dontsova ◽  
Dean Wilcox
Keyword(s):  
Aqueous Solutions ◽  
Degradation Products ◽  
Pure Water ◽  
Transformation Products ◽  
Water Soluble ◽  
Uv Exposure ◽  
Degradation Pathways ◽  
Solution Ph ◽  
Photo Degradation ◽  
Degradation Rates

Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. We irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10% degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were >80% for all three wavelengths. NTO degradation was greatest at 300 nm with 3% remaining after 32 h, followed by 254 nm (7% remaining) and 350 nm (20% remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48% by 32 h. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH.

The Influence of Adjusting Spray Solution pH on the Efficacy of Saflufenacil

2013 ◽  
Vol 27 (3) ◽  
pp. 445-447 ◽  
Author(s):  
Jared M. Roskamp ◽  
William G. Johnson
Keyword(s):  
Ammonium Sulfate ◽  
Weight Reduction ◽  
Seed Oil ◽  
Dry Weight ◽  
Final Solution ◽  
Solution Ph ◽  
Field Corn ◽  
Spray Solution ◽  
Initial Ph ◽  
Water Ph

Saflufenacil solubility and efficacy has been shown to be influenced by carrier water pH. This research was conducted to determine if altering the pH of a solution already containing saflufenacil would influence the efficacy of the herbicide. Saflufenacil at 25 g ai ha−1was applied to field corn in carrier water with one of five initial pH levels (4.0, 5.2, 6.5, 7.7, or 9.0) and then buffered to one of four final solution pH levels (4.0, 6.5, 9.0, or none) for a total of twenty treatments. All treatments included ammonium sulfate at 20.37 g L−1and methylated seed oil at 1% v/v. Generally, saflufenacil with a final solution pH of 6.5 or higher provided more dry weight reduction of corn than saflufenacil applied in a final pH of 5.2 or lower. When applying saflufenacil in water with an initial pH of 4.0 or 5.2, efficacy was increased by raising the final solution pH to either 6.5 or 9.0. Conversely, reduction in corn dry weight was less when solution pH of saflufenacil mixed in carrier water with an initial pH of 6.5 or 7.7 was lowered to a final pH of 4.0. When co-applying saflufenacil with herbicides that are very acidic, such as glyphosate, efficacy of saflufenacil may be reduced if solution pH is 5.2 or lower.

Mechanisms of aluminum tolerance in Triticum aestivum (wheat). IV. The role of ammonium and nitrate nutrition

1985 ◽  
Vol 63 (12) ◽  
pp. 2181-2186 ◽  
Author(s):  
Gregory J. Taylor ◽  
Charles D. Foy
Keyword(s):  
Triticum Aestivum ◽  
Phase Ii ◽  
Aluminum Tolerance ◽  
Triticum Aestivum L ◽  
Al Tolerance ◽  
Solution Ph ◽  
Ph Change ◽  
Initial Ph ◽  
Nutrient Solutions

Five cultivars of Triticum aestivum L. (wheat) were grown for 21 days in solution cultures with aluminum (+Al) (74 μM) and without Al (−Al) at an initial pH of 4.5. Patterns of nitrogen depletion and pH change were biphasic. Ammonium [Formula: see text] was rapidly depleted and solution pH declined during phase I. Depletion of nitrate [Formula: see text] was most rapid and solution pH increased after [Formula: see text] was exhausted from solutions (phase II). Cultivar tolerance to Al was negatively correlated with the rate of pH decline induced by cultivars, and the rate of pH decline was positively correlated with the rate at which cultivars depleted [Formula: see text] from +Al and −Al nutrient solutions. Cultivar tolerance to Al was also negatively correlated with the rate of [Formula: see text] depletion from +Al and −Al solutions. Cultivar tolerance to Al was positively correlated with the rate of [Formula: see text] depletion during phase II but only when plants were grown with Al. These results support the hypothesis that differential Al tolerance among cultivars of T. aestivum is caused by differences in the rate of [Formula: see text], and possibly [Formula: see text], uptake. Such diffferences in N preference may have caused differences in pH and Al solubility in the nutrient solutions.

The Treatment of Copper-Containing Wastewater by Electrolysis-Enhanced Micro-Electrolysis Fluidized Bed Method

2014 ◽  
Vol 926-930 ◽  
pp. 4402-4405
Author(s):  
Qiang Zhan ◽  
Xiao Jun Xu ◽  
Jing Zhao ◽  
Tian Guo Li
Keyword(s):  
Electron Microscope ◽  
Reaction Time ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Copper Ions ◽  
Sem Analysis ◽  
Solution Ph ◽  
Operation Conditions ◽  
Initial Ph ◽  
Scanning Electron

The effect of electrolysis-enhanced micro-electrolysis fluidized bed technology on treating cooper-containing wastewater had been systematic researched. Operation conditions including applied flow rate, voltage, solution pH and reaction time on the copper ions (Cu2+) removal effect, had been studied scanning electron microscope (SEM) analysis had been used to characterize the surface features of copper crystals in the fillers surface. The results show that the Cu2+ mainly removed by electrochemical deposition, the optimum operation conditions are: flow rate is 22mm/s, voltage is 12V, initial pH=4, the response time of 30 min.

Study on Ecological Value of Sustainable Development Based on China's Ancient Great Thinker's Thought on Ecological Ethics

2013 ◽  
Vol 869-870 ◽  
pp. 652-655
Author(s):  
Shi Hua Li
Keyword(s):  
Sustainable Development ◽  
Environmental Ethics ◽  
Theoretical Basis ◽  
Environmental Science ◽  
Ecological Ethics ◽  
Ecological Value ◽  
Philosophical Thinking ◽  
Basic Law ◽  
Living Organisms ◽  
The Relationship

Ecology is the science of studying the relationship between the living organisms and their environment. And the Environmental Science, which reveals the basic law of the harmonious development of society, economy and environment, is the discipline studying the interaction of people and environment. Ecology is not only the basic disciplines of environmental science, but also the scientifically recognized theoretical basis of environmental ethics. Tsunzi, a master on the Confucianism, one of the most distinguished Confucianists of the pre-Qin period, made the conception of sustainable development penetrate into his ecological ethics thoughts on the basis of philosophical thinking-Nature has its true law. If we hackle, inherit, comprehend, and utilize critically Tsunzis thought on ecological ethics, there will be some significant enlightening value for us to not only establish the theory of environmental ethics but also solve the increasing ecological crises facing humanity.

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