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 Crystal structure of the new hybrid material bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate

2015 ◽  
Vol 71 (11) ◽  
pp. 1384-1387
Author(s):  
Marwen Chouri ◽  
Habib Boughzala
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Molar Ratio ◽  
Water Molecules ◽  
Site Symmetry ◽  
Two Dimensional ◽  
Slow Evaporation ◽  
Solution Ph

The title compound bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was obtained by slow evaporation at room temperature of a hydrochloric aqueous solution (pH = 1) containing bismuth(III) nitrate and 1,4-diazabicyclo[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10]4−bioctahedra (site symmetry -1) separated by layers of organic 1,4-diazoniabicyclo[2.2.2]octane dications [(DABCOH2)2+] and water molecules. O—H...Cl, N—H...O and N—H...Cl hydrogen bonds lead to additional cohesion of the structure.

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.

scholarly journals Removal of phenol from aqueous solution by adsorption onto seashells: equilibrium, kinetic and thermodynamic studies

2013 ◽  
Vol 3 (2) ◽  
pp. 119-127 ◽  
Author(s):  
Papita Das Saha ◽  
Jaya Srivastava ◽  
Shamik Chowdhury
Keyword(s):  
Aqueous Solution ◽  
Adsorption Process ◽  
Phenol Concentration ◽  
Phenol Removal ◽  
Solution Ph ◽  
Initial Ph ◽  
Equilibrium Data ◽  
Initial Phenol Concentration ◽  
Adsorption Equilibrium Data ◽  
Adsorbent Dose

The efficacy of seashells as a new adsorbent for removal of phenol from aqueous solutions was studied by performing batch equilibrium tests under different operating parameters such as solution pH, adsorbent dose, initial phenol concentration, and temperature. The phenol removal efficiency remained unaffected when the initial pH of the phenol solution was in the range of 3–8. The amount of phenol adsorbed increased with increasing initial phenol concentration while it decreased with increasing temperature. The adsorption equilibrium data showed excellent fit to the Langmuir isotherm model with maximum monolayer adsorption capacity of 175.27 mg g−1 at pH 4.0, initial phenol concentration = 50 mg L−1, adsorbent dose = 2 g and temperature = 293 K. Analysis of kinetic data showed that the adsorption process followed pseudo-second-order kinetics. Activation energy of the adsorption process, calculated using the Arrhenius equation, was found to be 51.38 kJ mol−1, suggesting that adsorption of phenol onto seashells involved chemical ion-exchange. The numerical value of the thermodynamic parameters (ΔG0, ΔH0 and ΔS0) indicated that adsorption of phenol onto seashells was feasible, spontaneous and endothermic under the examined conditions. The study shows that seashells can be used as an economic adsorbent for removal of phenol from aqueous solution.

scholarly journals Synthesis of Calcium Silicate Hydrate from Coal Gangue for Cr(VI) and Cu(II) Removal from Aqueous Solution

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6192
Author(s):  
Qing Zhang ◽  
Guijian Liu ◽  
Shuchuan Peng ◽  
Chuncai Zhou
Keyword(s):  
Aqueous Solution ◽  
Reaction Time ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Variable Temperature ◽  
Coal Gangue ◽  
Molar Ratio ◽  
Solution Temperature ◽  
Solution Ph ◽  
Adsorption Temperature

Both the accumulation of coal gangue and potentially toxic elements in aqueous solution have caused biological damage to the surrounding ecosystem of the Huainan coal mining field. In this study, coal gangue was used to synthesize calcium silicate hydrate (C-S-H) to remove Cr(VI) and Cu(II)from aqueous solutions and aqueous solution. The optimum parameters for C-S-H synthesis were 700 °C for 1 h and a Ca/Si molar ratio of 1.0. Quantitative sorption analysis was done at variable temperature, C-S-H dosages, solution pH, initial concentrations of metals, and reaction time. The solution pH was precisely controlled by a pH meter. The adsorption temperature was controlled by a thermostatic gas bath oscillator. The error of solution temperature was controlled at ± 0.3, compared with the adsorption temperature. For Cr(VI) and Cu(II), the optimum initial concentration, temperature, and reaction time were 200 mg/L, 40 °C and 90 min, pH 2 and 0.1 g C-S-H for Cr(VI), pH 6 and 0.07 g C-S-H for Cu(II), respectively. The maximum adsorption capacities of Cr(VI) and Cu(II) were 68.03 and 70.42 mg·g−1, respectively. Furthermore, the concentrations of Cu(II) and Cr(VI) in aqueous solution could meet the surface water quality standards in China. The adsorption mechanism of Cu(II) and Cr(VI) onto C-S-H were reduction, electrostatic interaction, chelation interaction, and surface complexation. It was found that C-S-H is an environmentally friendly adsorbent for effective removal of metals from aqueous solution through different mechanisms.

scholarly journals Characterization, Dissolution, and Solubility of Lead Hydroxypyromorphite [Pb5(PO4)3OH] at 25–45°C

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yinian Zhu ◽  
Zongqiang Zhu ◽  
Xin Zhao ◽  
Yanpeng Liang ◽  
Yanhua Huang
Keyword(s):  
Molar Ratio ◽  
Stoichiometric Ratio ◽  
Ultrapure Water ◽  
Solution Ph ◽  
Free Energy Of Formation ◽  
Initial Ph ◽  
Naoh Solution ◽  
Water Ph ◽  
Ft Ir ◽  
Sem Analyses

Dissolution of the hydroxypyromorphite [lead hydroxyapatite, Pb5(PO4)3OH] in HNO3solution (pH = 2.00), ultrapure water (pH = 5.60), and NaOH solution (pH = 9.00) was experimentally studied at 25°C, 35°C, and 45°C. The XRD, FT-IR, and FE-SEM analyses indicated that the hydroxypyromorphite solids were observed to have indistinguishable change during dissolution. For the hydroxypyromorphite dissolution in aqueous acidic media at initial pH 2.00 and 25°C, the aqueous phosphate concentrations rose quickly and reached the peak values after 1 h dissolution, while the aqueous lead concentrations rose slowly and reached the peak values after 1440 h. The solution Pb/P molar ratio increased constantly from 1.10 to 1.65 near the stoichiometric ratio of 1.67 to 209.85~597.72 and then decreased to 74.76~237.26 for the dissolution at initial pH 2.00 and 25°C~45°C. The averageKspvalues for Pb5(PO4)3OH were determined to be 10−80.77(10−80.57−10−80.96) at 25°C, 10−80.65(10−80.38−10−80.99) at 35°C, and 10−79.96(10−79.38−10−80.71) at 45°C. From the obtained solubility data for the dissolution at initial pH 2.00 and 25°C, the Gibbs free energy of formation [ΔGfo] for Pb5(PO4)3OH was calculated to be −3796.71 kJ/mol (−3795.55~−3797.78 kJ/mol).

Rehydration of Calcined Mg-Al Hydrotalcite in Acidified Chloride-Containing Aqueous Solution

2007 ◽  
Vol 72 (9) ◽  
pp. 1284-1294 ◽  
Author(s):  
Bruno Kostura ◽  
František Kovanda ◽  
Marta Valášková ◽  
Juraj Leško
Keyword(s):  
Aqueous Solution ◽  
Crystalline Structure ◽  
Mixed Oxide ◽  
Molar Ratio ◽  
Final Solution ◽  
Constant Concentration ◽  
Rehydration Solution ◽  
Hcl Concentration ◽  
Hydroxide Hydrate

The rehydration of periclase-like Mg-Al mixed oxide obtained by calcination of hydrotalcite- like precursor with a Mg/Al molar ratio of 2 was carried out in KCl-HCl solutions at various pH and constant concentration of Cl-. A buffer equilibrium accompanied by leaching out of Mg2+ cations from the solid was observed during rehydration, when reconstruction of the layered hydrotalcite structure takes place. With increasing HCl concentration in the rehydration solution, the Mg/Al molar ratio in the obtained solid gradually decreased from about 1.5 to 0.3. An anomaly was found, when the increasing concentration of acid resulted in increasing pH of final solution. The XRD measurements showed that the initially formed hydroxide form of hydrotalcite is transformed into randomly interstratified forms of the Mg-Al hydroxide hydrate/Mg-Al chloride hydroxide hydrate, which are accompanied by the release of OH- anions into solution. The crystalline structure of rehydrated product decreased as Mg2+ cations were released into solution, which was accompanied by incorporation of Cl- into the solid.

Germanium Co-Precipitation with Ferric Hydroxide: A Lab-Scale Study

2012 ◽  
Vol 581-582 ◽  
pp. 1050-1053
Author(s):  
Ke Yun Chen ◽  
Chen Liu ◽  
Duo Qiang Liang ◽  
Hang Jun He ◽  
Qiang Huang ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Ferric Hydroxide ◽  
Sulfate Solution ◽  
Molar Ratio ◽  
Final Solution ◽  
Solution Ph ◽  
Acid Media ◽  
Dilute Sulfuric Acid ◽  
Co Precipitation ◽  
Germanium Concentration

Lab-scale germanium co-precipitation with ferric hydroxide in dilute sulfuric acid media was studied. The experiments of co-precipitation of germanium and ferric hydroxide were performed by neutralization of the germanium-ferric sulfate solution via adding calcium hydroxide powder. The variables affecting the germanium precipitation yield were investigated. The experimental results show that high initial germanium concentration, high ferric/germanium molar ratio, high final solution pH, low ion strength and slow temperature will contribute to high germanium precipitation yield.

scholarly journals Preparation and characterization of iron-copper binary oxide and its effective removal of antimony(III) from aqueous solution

2016 ◽  
Vol 74 (2) ◽  
pp. 393-401 ◽  
Author(s):  
Yongchao Li ◽  
Bing Geng ◽  
Xiaoxian Hu ◽  
Bozhi Ren ◽  
Andrew S. Hursthouse
Keyword(s):  
Aqueous Solution ◽  
Photoelectron Spectroscopy ◽  
Binary Oxide ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
X Ray ◽  
Freundlich Adsorption Isotherm ◽  
Co Precipitation

An Fe-Cu binary oxide was fabricated through a simple co-precipitation process, and was used to remove Sb(III) from aqueous solution. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and N2 adsorption–desorption measurements demonstrated that the Fe-Cu binary oxide consisted of poorly ordered ferrihydrite and CuO, and its specific surface area was higher than both iron oxide and copper oxide. A comparative test indicated that Fe/Cu molar ratio of prepared binary oxide greatly influenced Sb(III) removal and the optimum Fe/Cu molar ratio was about 3/1. Moreover, a maximum adsorption capacity of 209.23 mg Sb(III)/g Fe-Cu binary oxide at pH 5.0 was obtained. The removal of Sb(III) by Fe-Cu binary oxide followed the Freundlich adsorption isotherm and the pseudo-second-order kinetics in the batch study. The removal of Sb(III) was not sensitive to solution pH. In addition, the release of Fe and Cu ions to water was very low when the pH was greater than 6.0. X-ray photoelectron spectroscopy analysis confirmed that the Sb(III) adsorbed on the surface was not oxidized to Sb(V).

Removal of Lead from Aqueous Solution by Sewage Sludge Carbon Adsorbent

2011 ◽  
Vol 239-242 ◽  
pp. 1866-1869 ◽  
Author(s):  
Chang Bin Xia ◽  
Fu Jian Zhou ◽  
Yuan Chen ◽  
Ling Zhang
Keyword(s):  
Aqueous Solution ◽  
Sewage Sludge ◽  
Metal Removal ◽  
Carbon Adsorbent ◽  
Ion Concentration ◽  
Lead Ion ◽  
Solution Ph ◽  
Initial Ph ◽  
Equilibrium Data ◽  
Efficient Adsorbent

The capacity of sewage sludge carbon (SSC) for the removal of lead ion from aqueous solution has been studied under different conditions,namely SSC particle size,initial pH,initial Pb2+ ion concentration and solution temperature.The results show that equilibrium data obtained fit the Langmuir adsorption isotherms,this SSC is an efficient adsorbent for removing lead ion.The finer the SSC particle used,the higher the metal adsorption capacity.An initial solution pH ≥4.5 is favourable for obtaining high metal removal.

Fe(II) Biosorption Using Pleurotus Spent Mushroom Compost as Biosorbent under Batch Experiment

2014 ◽  
Vol 695 ◽  
pp. 314-318
Author(s):  
Ain Nihla Kamarudzaman ◽  
Tay Chia Chay ◽  
Amnorzahira Amir ◽  
Suhaimi Abdul Talib
Keyword(s):  
Aqueous Solution ◽  
Laboratory Study ◽  
Contact Time ◽  
Batch Experiment ◽  
Mushroom Compost ◽  
Spent Mushroom Compost ◽  
Initial Ph

A laboratory study was conducted to optimize the various parameters involved in Fe (II) biosorption under batch experiment and also to evaluate the biosorption performance using Pleurotus spent mushroom compost as biosorbent. The optimum Fe (II) biosorption was achieved at an initial pH 5, contact time of 30 minutes and initial Fe (II) concentration of 10 mg/L using 0.75 g biosorbent dosages. The study concluded that the Pleurotus spent mushroom compost was capable for removing of Fe (II) from aqueous solution.

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