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).

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.

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 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 Enhanced Degradation of Phenol by a Fenton-Like System (Fe/EDTA/H2O2) at Circumneutral pH

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 474 ◽  
Author(s):  
Selamawit Ashagre Messele ◽  
Christophe Bengoa ◽  
Frank Erich Stüber ◽  
Jaume Giralt ◽  
Agustí Fortuny ◽  
...  
Keyword(s):  
Chelating Agents ◽  
Ethylenediaminetetraacetic Acid ◽  
Chelating Agent ◽  
Nitrilotriacetic Acid ◽  
Molar Ratio ◽  
Phenol Removal ◽  
Stoichiometric Ratio ◽  
Initial Ph ◽  
Phenol Conversion ◽  
Circumneutral Ph

This work deals with the degradation of phenol based on the classical Fenton process, which is enhanced by the presence of chelating agents. Several iron-chelating agents such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriamine pentaacetic acid (DTPA), and ethylenediamine-N,N’-diacetic acid (EDDA) were explored, although particular attention was given to EDTA. The effect of the molar ligand to iron ratio, EDTA:Fe, initial pH, and temperature on the oxidation process was studied. The results demonstrate that the proposed alternative approach allows the capacity for degrading phenol to be extended from the usual acidic pH (around 3.0) to circumneutral pH range (6.5–7.5). The overall feasibility of the process depends on the concentration of the chelating agent and the initial pH of the solution. The maximum phenol conversion, over 95%, is achieved using a 0.3 to 1 molar ratio of EDTA:Fe, stoichiometric ratio of H2O2 at an initial pH of 7.0, and a temperature of 30 °C after 2 hours of reaction, whereas only 10% of phenol conversion is obtained without EDTA. However, in excess of ligand (EDTA:Fe > 1), the generation of radicals seems to be strongly suppressed. Improvement of the phenol removal efficiency at neutral pH also occurs for the other chelating agents tested.

Hydrolysis of polydimethylsiloxane fluids in controlled aqueous solutions

2013 ◽  
Vol 68 (4) ◽  
pp. 813-820 ◽  
Author(s):  
Gaëlle Ducom ◽  
Baptiste Laubie ◽  
Aurélie Ohannessian ◽  
Claire Chottier ◽  
Patrick Germain ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Wastewater Treatment Plants ◽  
Degradation Products ◽  
Kinetic Studies ◽  
Solution Ph ◽  
Degradation Kinetic ◽  
Silicon Compounds ◽  
Alkaline Conditions ◽  
Naoh Solution ◽  
Water Ph

Accelerated degradation tests were performed on polydimethylsiloxane (PDMS) fluids in aqueous solutions and in extreme chemical conditions (pH 2–4 and 9–12). Results confirmed that silicones can be degraded by hydrolysis. Higher degradation levels were achieved in very acidic and alkaline conditions. Degradation products are probably polar siloxanols. In alkaline conditions, the counter-ion was found to have a strong influence on degradation level. Degradation kinetic studies (46 days) were also performed at different pH values. Supposing zeroth-order kinetics, degradation rate constants at 24 °C were estimated to 0.28 mgSi L−1 day−1 in NaOH solution (pH 12), 0.07 mgSi L−1 day−1 in HCl solution (pH 2) and 0.002 mgSi L−1 day−1 in demineralised water (pH 6). From these results, the following hypothesis was drawn: PDMS hydrolysis could occur in wastewater treatment plants and in landfill cells. It may be a first step in the formation of volatile organic silicon compounds (VOSiCs, including siloxanes) in biogas: coupled to biodegradation and (self-) condensation of degradation products, it could finally lead to VOSiCs.

scholarly journals Preparation, Characterization and Study of the Photodecolorization of Mixed-Ligand Binuclear Co(II) Complex of Schiff Base by ZnO

2020 ◽  
Vol 20 (2) ◽  
pp. 404 ◽  
Author(s):  
Suhad Kareem Abass ◽  
Jassim Abbas Al-Hilfi ◽  
Sawsan Khudhair Abbas ◽  
Luma Majeed Ahmed
Keyword(s):  
Schiff Base ◽  
Binuclear Complex ◽  
Uv Light ◽  
Mixed Ligand ◽  
Molar Ratio ◽  
Melting Points ◽  
Initial Ph ◽  
Ft Ir ◽  
Prepared Complex

In this work, a new mixed-ligand binuclear Co(II) complex of Schiff base was prepared. Moreover, the characterization of this prepared complex was performed by measurement of melting points, UV-Vis spectra, FT-IR spectra, and magnetic susceptibility measurements, and later compared with metal and ligand solutions. It has been discovered that the Schiff bases with Co(II) ion forms a binuclear complex with a stoichiometry of molar ratio 1:2 from “metal:ligand”. The photodecolorization of this complex was done under UV light for ZnO's suspension solution. The results of this photodecolorization showed that the greatest efficiency was obtained with the use of ZnO dose of 300 mg/100 mL and at an initial pH of 7. The decolorization activation energy for this complex is a small value of 11.289 kJ mol–1. Additionally, the thermodynamic study for this reaction is non-spontaneous, endothermic and less random.

scholarly journals Separate As(V) from solution by mesoporous Y-Al binary oxide: batch experiments

2017 ◽  
Vol 77 (4) ◽  
pp. 871-879
Author(s):  
Hang Liu ◽  
Caiyun Han ◽  
Liu Yang ◽  
Dekun Liu ◽  
Yongming Luo
Keyword(s):  
Point Of Zero Charge ◽  
Molar Ratio ◽  
Maximum Adsorption Capacity ◽  
Impregnation Method ◽  
Batch Experiments ◽  
Adsorption Performance ◽  
Initial Ph ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Adsorption Desorption

Abstract Contaminant arsenic(V) has been regarded as one of the top-priority pollutants to remove from water. In this contribution, different mesoporous Y-Al binary oxides were prepared by the wet impregnation method via varying the molar ratio of Y/Al in the range of 0.029 to 0.116. The manufactured materials were employed as adsorbent to separate arsenic(V) from water. The adsorbent was characterized by N2 adsorption–desorption isotherm, point of zero charge (PZC) and Fourier transform infrared (FT-IR). Furthermore, the effect of experimental parameters on adsorption performance was evaluated by batch experiments, including the molar ratio of Y/Al, adsorbent dosages and contact time, initial concentration, initial pH and temperature. The results indicated that the adsorbent presented an optimal adsorption performance for As(V) uptake when the molar ratio of Y/Al was 0.058. The obtained experimental data were best fitted by Langmuir isotherm and the maximum adsorption capacity was 60.93 mg/g at pH 6.6 ± 0.1. Additionally, according to the results of adsorption kinetics, it was pronounced that adsorption process was complied with pseudo-second-order model. The adsorption thermodynamic suggested that the adsorption of As(V) is endothermic and spontaneous natural. Moreover, based on the results of FT-IR, PZC and initial pH, it is demonstrated that ion-exchange and electrostatic interaction were the dominating adsorption mechanism.

Adsorption Properties of Dye onto Mg/Al-CO3 Layered Double Hydroxide

2012 ◽  
Vol 455-456 ◽  
pp. 677-682
Author(s):  
Li Fang Zhang ◽  
De Zhou Wei
Keyword(s):  
Layered Double Hydroxide ◽  
Dye Removal ◽  
Adsorption Equilibrium ◽  
Freundlich Isotherm ◽  
Molar Ratio ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Initial Ph ◽  
Double Hydroxide

Adsorption of reactive red on Mg/Al-CO3 layered double hydroxide in a batch stirred system was investigated. Experiments were carried out as function of Mg/Al molar ratio, contact time, initial pH, adsorbent amount and temperature. It was found that the maximum dye removal was at Mg/Al molar ratio of 3. Solution pH ranging from 2-8 had little effect on adsorption rate. Dye removal decreased with increased temperature in studied temperature range. The Langmuir and Freundlich isotherm models were used for modeling the adsorption equilibrium. The adsorption equilibrium data could well interpreted by the Langmuir models with maximum adsorption capacity of 131.58 mg/g (R2=0.9986). The results indicate the possible dye removal from water by using Mg/Al-CO3 layered double hydroxide.

Synthesis of N2, N6-bis(5-methylthiazol-2-yl)pyridine-2,6-dicarboxamide fluoroscent sensor for detection of Cu2+ and Ni2+ Ions

Drug Research ◽  
2021 ◽  
Author(s):  
Anuroop Kumar ◽  
Netrapal Singh ◽  
Mordhwaj Kumar ◽  
Uma Agarwal
Keyword(s):  
Spectral Analysis ◽  
Detection Limit ◽  
Metal Ions ◽  
1H Nmr Spectroscopy ◽  
Stoichiometric Ratio ◽  
Selective Detection ◽  
Ft Ir ◽  
Uv Visible ◽  
Complexes With Metal Ions ◽  
Competitive Ions

AbstractThis article reports an amide based Chemosensor used for selective detection of divalent Cu+2 and Ni+2 ions via Fluorescence turn off. The selective sensing ability of Chemosensor was investigated in presence of different metal ions Mg2+, Ag+, Fe2+, K+, Cu2+, Ni2+, Hg2+, Pb2+, Mn2+, Pd2+, Cd2+ and Mn3+ as competitive ions. The receptor i. e. Chemosensor formed complexes with metal ions in 1:1 stoichiometric ratio. The detection limit and binding constant calculated as 1.92×10–4 and 1.4×10–4 M and 2.16×103 M−1 and 3.09×103 M−1 for Cu2+ and Ni2+ions respectively. The complexes were characterized by UV/visible, FT-IR, 13C NMR and 1H NMR spectroscopy. Further the structure and Crystallinity were calculated by P-XRD spectral analysis. The crystallinity found to be 65.27 and 67.87% respectively

scholarly journals Removal of Chromium(III) and Cadmium(II) Heavy Metal Ions from Aqueous Solutions Using Treated Date Seeds: An Eco-Friendly Method

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3718
Author(s):  
Mohammad Azam ◽  
Saikh Mohammad Wabaidur ◽  
Mohammad Rizwan Khan ◽  
Saud I. Al-Resayes ◽  
Mohammad Shahidul Islam
Keyword(s):  
Metal Ions ◽  
Adsorption Capacity ◽  
Low Cost ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Surface Analysis Techniques ◽  
Adsorption Processes ◽  
Ft Ir ◽  
Metal Elution ◽  
Date Pits

The aim of the research was to prepare low-cost adsorbents, including raw date pits and chemically treated date pits, and to apply these materials to investigate the adsorption behavior of Cr(III) and Cd(II) ions from wastewater. The prepared materials were characterized using SEM, FT-IR and BET surface analysis techniques for investigating the surface morphology, particle size, pore size and surface functionalities of the materials. A series of adsorption processes was conducted in a batch system and optimized by investigating various parameters such as solution pH, contact time, initial metal concentrations and adsorbent dosage. The optimum pH for achieving maximum adsorption capacity was found to be approximately 7.8. The determination of metal ions was conducted using atomic adsorption spectrometry. The experimental results were fitted using isotherm Langmuir and Freundlich equations, and maximum monolayer adsorption capacities for Cr(III) and Cd(II) at 323 K were 1428.5 and 1302.0 mg/g (treated majdool date pits adsorbent) and 1228.5 and 1182.0 mg/g (treated sagai date pits adsorbent), respectively. It was found that the adsorption capacity of H2O2-treated date pits was higher than that of untreated DP. Recovery studies showed maximal metal elution with 0.1 M HCl for all the adsorbents. An 83.3–88.2% and 81.8–86.8% drop in Cr(III) and Cd(II) adsorption, respectively, were found after the five regeneration cycles. The results showed that the Langmuir model gave slightly better results than the Freundlich model for the untreated and treated date pits. Hence, the results demonstrated that the prepared materials could be a low-cost and eco-friendly choice for the remediation of Cr(III) and Cd(II) contaminants from an aqueous solution.

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