Dependence of Stability of Sr5(AsO4)3OH on pH Value

2014 ◽  
Vol 692 ◽  
pp. 229-233
Author(s):  
Yan Hua Huang ◽  
Zong Ning Li ◽  
Hui Qin ◽  
Zong Qiang Zhu ◽  
Yi Nian Zhu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Ph Value ◽  
Reaction System ◽  
Initial Solution ◽  
Alkaline Solutions ◽  
Solution Ph ◽  
Batch Dissolution ◽  
Initial Ph

The object of this work was to determine the solubility and stability of the synthetic Sr5(AsO4)3OH solid solution at 25°C and the different initial pHs (pH at 2, 6 and 9) by batch dissolution experiments. The results indicated that with the initial pH value of 2, 6 and 9, the reaction system reached equilibrium after 2880h, and by that time the pH value of the solution reached, 7.90, 8.74 and 8.27 respectively. The concentration of strontium and arsenic in the initial solution pH at 2 are higher than that of solutions pH at 6 and 9. While the concentration of strontium in neutral or alkaline solutions is low and stays unchanged.

Pathway and Kinetic of Dechlorination of Trichloroethylene in Water by Supported Nanoscale Bimetallic Fe-Cu Particles

2011 ◽  
Vol 213 ◽  
pp. 126-130
Author(s):  
Huan Zhang ◽  
Ying Xue Zheng ◽  
Hai Tao Wang
Keyword(s):  
Ph Value ◽  
Reaction System ◽  
Surface Concentration ◽  
Batch Experiments ◽  
Solution Ph ◽  
Cu Content ◽  
Kinetics Studies ◽  
Reaction Solution ◽  
Pseudo Second Order ◽  
Dechlorination Reaction

In this paper, exfoliated graphite supported nanoscale Fe-Cu is synthesized by aqueous-phase reductive method. The effect trichloroethene (TCE) reduction by the supported nanoscale Fe-Cu bimetal is researched in the batch experiments. Kinetics studies show that the reduction of TCE process obeys pseudo-second-order kinetics. The kinetic constants of TCE reduction by supported nano bimetal are measured at different nano Fe0 dosage and Cu content on bimetal in this study. When the dosage of supported nano Fe0 in bimetal with 4wt% Cu is 1.25g/L in reaction solution, the kSA of dechlorination reaction for TCE is higher than other nano Fe0 dosage. The dechlorination speed becomes lower as well as kSA and kobs decreasing with increasing the Fe0 dosage. Supported Fe-Cu bimetal with 4wt% Cu content exhibits the best dehalogenation effect than those with other contents of Cu. The generation of H2 and effect of Cu analysis influence the TCE dechloriation and hydrogenation in the surface of bimetal to a different extent. Excess nano Fe0 existing in the reaction system can generate plenty of H2 as well as increasing the solution pH value so that decrease the surface concentration of bimetal reactive sites and then hinder the TCE dechlorination in surface of bimetal. Cu as catalysis metal could accelerate the process of TCE dechlorination and hydrogenation.

Metal Adsorbent Prepared from Coir Pith as Agricultural Waste: Adsorption of Zn(II) and Pb(II) from Aqueous Solution

2013 ◽  
Vol 545 ◽  
pp. 101-108 ◽  
Author(s):  
Kitirote Wantala ◽  
Nusavadee Pojananukij ◽  
Pongsert Sriprom ◽  
Tinnakorn Kumsaen ◽  
Arthit Neramittagapong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Calcination Temperature ◽  
Ph Value ◽  
Agricultural Waste ◽  
Initial Solution ◽  
Order Kinetic ◽  
Solution Ph ◽  
Freundlich Isotherms ◽  
Coir Pith

Adsorption of Zn(II) and Pb(II) from aqueous solution were studied by using modified coir pith as an adsorbent. The extended adsorption conditions were investigated as a function of calcination temperature, contact time, adsorbent size, initial pH of solution and initial Zn(II) and Pb(II) concentrations. The adsorption capacity increased rapidly in first 5 minute and reached equilibrium in 120 minutes for Zn(II) and 10 minutes for Pb(II). In case of Zn(II); the results showed that the calcination temperature of modified coir pith above 600oC gave the higher adsorption capacity. The sizes of modified coir pith have no effect on the adsorption capacity. The adsorption capacity increased with increasing initial solution pH value. In case of Pb(II); the calcination temperature of modified coir pith showed no effect on the adsorption capacity. The sizes of modified coir pith showed a little effect on the adsorption capacity. The adsorption capacity increased with increasing of initial solution pH value up to pH of 3 and then stable. The results also corresponded with the Langmuir and Freundlich isotherms and pseudo second order kinetic adsorption models. The modified coir pith gave a higher Zn(II) and Pb(II) adsorption capacity of 29.33 mg Zn(II)/g adsorbent and 36.50 mg Pb(II)/g adsorbent, respectively.

scholarly journals Effect of the Acidic and Alkaline Solutions on K2CrO4 and K2Cr2O7 by Ultraviolet and Visible Measurement

2019 ◽  
Vol 30 (1) ◽  
pp. 221
Author(s):  
Mohammad Radi Mohammad ◽  
Hasanain Saad Azeez
Keyword(s):  
Ph Value ◽  
Red Shift ◽  
Alkaline Solutions ◽  
Visible Spectroscopy ◽  
Solution Ph ◽  
Effect Of Ph ◽  
Ph Values ◽  
Uv Visible

In this work different amount of acidic (HCl) and alkaline (NaOH) solutions were added to stoke solutions of K2CrO4 and K2Cr2O7 to show the effect of pH values on their spectra. The results of UV-Visible spectroscopy shows that, the Changing of solution pH value when drops of HCl were added led to shift wavelength of K2CrO4 spectrum while no change has been occurred in K2Cr2O7 spectrum. However, Changing PH values solution by adding drops of NaOH led to change in wavelength red shift for K2Cr2O7 while no changes has been occurred in spectrum of K2CrO4.

scholarly journals NOxRemoval from Simulated Marine Exhaust Gas by Wet Scrubbing Using NaClO Solution

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Zhitao Han ◽  
Bojun Liu ◽  
Shaolong Yang ◽  
Xinxiang Pan ◽  
Zhijun Yan
Keyword(s):  
Removal Efficiency ◽  
Reaction Mechanisms ◽  
Complete Removal ◽  
Initial Solution ◽  
Exhaust Gas ◽  
Solution Ph ◽  
Wet Scrubbing ◽  
Initial Ph

The experiments were performed in a lab-scale countercurrent spraying reactor to study the NOxremoval from simulated gas stream by cyclic scrubbing using NaClO solution. The effects of NaClO concentration, initial solution pH, coexisting gases (5% CO2and 13% O2), NOxconcentration, SO2concentration, and absorbent temperature on NOxremoval efficiency were investigated in regard to marine exhaust gas. When NaClO concentration was higher than 0.05 M and initial solution pH was below 8, NOxremoval efficiency was relatively stable and it was higher than 60%. The coexisting CO2(5%) had little effect on NOxremoval efficiency, but the outlet CO2concentration decreased slowly with the initial pH increasing from 6 to 8. A complete removal of SO2and NO could be achieved simultaneously at 293 K, initial pH of 6, and NaClO concentration of 0.05 M, while the outlet NO2concentration increased slightly with the increase of inlet SO2concentration. NOxremoval efficiency increased slightly with the increase of absorbent temperature. The relevant reaction mechanisms for the oxidation and absorption of NO with NaClO were also discussed. The results indicated that it was of great potential for NOxremoval from marine exhaust gas by wet scrubbing using NaClO solution.

scholarly journals Kinetics of Cr(VI) adsorption from aqueous medium onto bentonite

2020 ◽  
Vol 11 (15) ◽  
Author(s):  
Rada Petrović
Keyword(s):  
Heavy Metals ◽  
Aqueous Medium ◽  
Ph Value ◽  
Second Order ◽  
Human Beings ◽  
Adsorption Model ◽  
Solution Ph ◽  
Initial Ph ◽  
Isotherm Adsorption ◽  
Pseudo Second Order

Because of its abundance and toxicity, heavy metals have become a seriousenvironmental problem. The presence of heavy metals, such as Cr(VI), in thewatercourses leads to numerous health problems in humans and animals. Cr(VI) ishighly toxic, even in low concentrations. Because of its carcinogenic, mutagenic andteratogenic effects on human beings, Cr(VI) is considered one of the most criticalpollutants. Due to this, it is necessary to remove Cr(VI) from wastewater prior to itsdischarge into the recipient.This paper studied the possibility for application of bentonite as an adsorbent forCr(VI) from aqueous medium. The characterization of bentonite was determined withchemical composition, specific surface, XRD method and FTIR. Optimal parameterssuch as pH of solution, adsorbent weight, time of adsorption and temperaturewere examined. Values of those parameters were: initial pH value of solution pH=2,adsorbent weight 2 g, time of adsorption 60 min, temperature 308 K. Experimentaldata were obtained by Freundlich and Langmuir isotherm adsorption models as wellas pseudo-first and pseudo-second order kinetics. Results were best described withFreundlich isotherm adsorption model and pseudo-second order kinetics.

Degradating Organophosphosphous Pesticides Wastewater by Sonophotocatalytic Oxidation Technology

2013 ◽  
Vol 634-638 ◽  
pp. 338-344
Author(s):  
Xue Li Xu ◽  
Wei Song ◽  
Li Zhang
Keyword(s):  
Oxidation Reaction ◽  
Degradation Rate ◽  
Ph Value ◽  
Solution Concentration ◽  
Initial Solution ◽  
Optimal Time ◽  
Factors Affecting ◽  
Initial Solution Concentration ◽  
Initial Ph ◽  
Oxidation Technology

Organophosphosphous pesticides wastewater was degradated by sonophotocatalytic oxidation technology,and some factors affecting sonophotocatalytic oxidation reaction were studied in details such as different degradation modes,the time of degradation、initial solution concentration 、initial pH value、the amount of catalyst and the effect of Fenton,etc.In the end the optimal conditons were determined.The conclusion we drawed was that the optimal time of degradation was 100min 、initial solution concentration was 100mg／L、initial pH value was 7、the amount of catalyst was 0.6g,moreover the adding of Fenton could greatly enhance the degradation rate.

scholarly journals Hydrothermal Synthesis of Various Shape-Controlled Europium Hydroxides

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 529
Author(s):  
Hongjuan Zheng ◽  
Kongjun Zhu ◽  
Ayumu Onda ◽  
Kazumichi Yanagisawa
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ph Value ◽  
Hydrothermal Temperature ◽  
X Ray ◽  
Hydrothermal Reactions ◽  
Starting Solution ◽  
Initial Ph ◽  
Shape Controlled ◽  
Scanning Electron

Eu(OH)3 with various shape-controlled morphologies and size, such as plate, rod, tube, prism and nanoparticles was successfully synthesized through simple hydrothermal reactions. The products were characterized by XRD (X-Ray Powder Diffraction), FE-SEM (Field Emission- Scanning Electron Microscopy) and TG (Thermogravimetry). The influence of the initial pH value of the starting solution and reaction temperature on the crystalline phase and morphology of the hydrothermal products was investigated. A possible formation process to control morphologies and size of europium products by changing the hydrothermal temperature and initial pH value of the starting solution was proposed.

scholarly journals Separation of Radionuclides from a Rare Earth-Containing Solution by Zeolite Adsorption

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 20
Author(s):  
Deniz Talan ◽  
Qingqing Huang
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Contact Time ◽  
Separation Efficiency ◽  
Ph Value ◽  
Solid Phase ◽  
Separation Performance ◽  
Solution Ph ◽  
Zeolite Sample ◽  
Alternative Sources

The increasing industrial demand for rare earths requires new or alternative sources to be found. Within this context, there have been studies validating the technical feasibility of coal and coal byproducts as alternative sources for rare earth elements. Nonetheless, radioactive materials, such as thorium and uranium, are frequently seen in the rare earths’ mineralization, and causes environmental and health concerns. Consequently, there exists an urgent need to remove these radionuclides in order to produce high purity rare earths to diversify the supply chain, as well as maintain an environmentally-favorable extraction process for the surroundings. In this study, an experimental design was generated to examine the effect of zeolite particle size, feed solution pH, zeolite amount, and contact time of solid and aqueous phases on the removal of thorium and uranium from the solution. The best separation performance was achieved using 2.50 g of 12-µm zeolite sample at a pH value of 3 with a contact time of 2 h. Under these conditions, the adsorption recovery of rare earths, thorium, and uranium into the solid phase was found to be 20.43 wt%, 99.20 wt%, and 89.60 wt%, respectively. The Freundlich adsorption isotherm was determined to be the best-fit model, and the adsorption mechanism of rare earths and thorium was identified as multilayer physisorption. Further, the separation efficiency was assessed using the response surface methodology based on the development of a statistically significant model.

scholarly journals The sorption of inorganic arsenic on modified sepiolite: Effect of hydrated iron(III)-oxide

2014 ◽  
Vol 79 (7) ◽  
pp. 815-828 ◽  
Author(s):  
Nikola Ilic ◽  
Slavica Lazarevic ◽  
Vladana Rajakovic-Ognjanovic ◽  
Ljubinka Rajakovic ◽  
Djordje Janackovic ◽  
...  
Keyword(s):  
Sorption Capacity ◽  
Arsenic Removal ◽  
Ph Value ◽  
Inorganic Arsenic ◽  
Arsenic Species ◽  
Deionized Water ◽  
Order Kinetic ◽  
Initial Ph ◽  
Order Kinetic Model ◽  
Pseudo Second Order

The sorption of inorganic arsenic species, As(III) and As(V), from water by sepiolite modified with hydrated iron(III) oxide was investigated at 25 ?C through batch studies. The influence of the initial pH value, the initial As concentrations, the contact time and types of water on the sorption capacity was investigated. Two types of water were used, deionized and groundwater. The maximal sorption capacity for As(III) from deionized water was observed at initial and final pH value 7.0, while the bonding of As(V) was observed to be almost pH independent for pH value in the range from 2.0 to 7.0, and the significant decrease in the sorption capacity was observed at pH values above 7.0. The sorption capacity at initial pH 7.0 was about 10 mg g?1 for As(III) and 4.2 mg g?1 for As(V) in deionized water. The capacity in groundwater was decreased by 40 % for As(III) and by 20 % for As(V). The Langmuir model and pseudo-second order kinetic model revealed good agreement with the experimental results. The results show that Fe(III)-modified sepiolite exhibits significant affinity for arsenic removal and it has a potential for the application in water purification processes.

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