Comparison of electrochemical current noise signals arising from symmetrical and asymmetrical electrodes made of Al alloys at different pH values using statistical and wavelet analysis. Part I: Neutral and acidic solutions

2014 ◽  
Vol 148 ◽  
pp. 127-144 ◽  
Author(s):  
M.J. Bahrami ◽  
M. Shahidi ◽  
S.M.A. Hosseini
Keyword(s):  
Wavelet Analysis ◽  
Al Alloys ◽  
Current Noise ◽  
Acidic Solutions ◽  
Ph Values ◽  
Electrochemical Current

scholarly journals Immobilization of Cd, Zn, and Pb from Soil Treated by Limestone with Variation of pH Using a Column Test

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Sung-Wook Yun ◽  
Chan Yu
Keyword(s):  
South Korea ◽  
Water Systems ◽  
Metal Mobility ◽  
Acid Solutions ◽  
Test Results ◽  
Column Test ◽  
Acidic Solutions ◽  
Ph Values ◽  
Metal Mines ◽  
Site Restoration

Decades of mining in South Korea have resulted in the contamination of large amounts of soil by metals. The most feasible approach to site restoration requires the use of a stabilization agent to reduce metal mobility. This study examined the leaching characteristics of limestone used as a stabilization agent when subjected to solutions of differing pH. In a laboratory-scale column test, solutions with pH values of 3.5, 4.6, and 5.6, representing acidic to nonacidic rainfall, were applied to soil mixed with limestone. Test results indicate that metal components can be released with the addition of acidic solutions, even if the soil is highly alkaline. Cd and Zn, in particular, exhibited abrupt or continuous leaching when exposed to acid solutions, indicating the potential for contamination of water systems as metal-laden soils are exposed to the slightly acidic rainfall typical of South Korea. Treatment using stabilization agents such as limestone may reduce leaching of metals from the contaminated soil. Stabilizing metal-contaminated farmland is an economical and feasible way to reduce pollutants around abandoned metal mines.

scholarly journals Boron removal from aqueous solutions by a polyethylenimine-epichlorohydrin resin

2018 ◽  
Vol 83 (2) ◽  
pp. 251-264 ◽  
Author(s):  
Sofia Sarri ◽  
Panagiotis Misaelides ◽  
Dimitrios Zamboulis ◽  
Jolanta Warchoł
Keyword(s):  
Aqueous Solutions ◽  
Boron Concentration ◽  
Kinetic Studies ◽  
Alkaline Solutions ◽  
Competitive Sorption ◽  
Boron Removal ◽  
Boron Uptake ◽  
Acidic Solutions ◽  
Ph Values ◽  
Batch Technique

The use of a polyethylenimine?epichlorohydrin resin for the boron removal from aqueous solutions (boron concentration: 100?5000 mg L-1) of non-adjusted and pre-adjusted pH (pHnat, pHinit 8.0, 9.0 and 10.0) aqueous solutions was investigated using a batch technique. The boron concentration in the solutions after sorption was determined photometrically. The results indicated that the pH-dependent boron uptake was related to the protonation/deprotonation of the surface functional groups of the resin and to the boron speciation in solutions of different pH values. The maximum boron sorption capacity observed in solutions of pH 9.0 was 55 mg g-1 exceeding the majority of other commercial or alternative sorbents. Five empirical adsorption equations (Freundlich, Langmuir, Redlich?Peterson, Langmuir?Freundlich and Toth) were applied to the modelling of the boron adsorption equilibrium. The modelling results identified the homogenous boron sorption from acidic and heterogeneous from alkaline solutions. At alkaline pH, the system non-ideality can originate either from the different binding mechanism or from the competitive sorption of different boron species. The homogenous type boron sorption from acidic solutions was further confirmed by kinetic studies

The stationarity characteristics of electrochemical current noise

2002 ◽  
Vol 49 (1) ◽  
pp. 27-32 ◽  
Author(s):  
A. Zielinski ◽  
J. Smulko ◽  
A. Krakowiak ◽  
K. Darowicki
Keyword(s):  
Current Noise ◽  
Electrochemical Current

Study on Stability of AgI/TiO2 Visible Light Photocatalysts in Solutions of Various pH Values

2011 ◽  
Vol 399-401 ◽  
pp. 1272-1275
Author(s):  
Lu Feng ◽  
Ke Feng He ◽  
Wan Ping Chen
Keyword(s):  
Visible Light ◽  
Absorption Edge ◽  
Ph Value ◽  
Alkaline Treatment ◽  
Alkaline Solutions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Acidic Solutions ◽  
Ph Values ◽  
Vis Spectroscopy

Nanostructured AgI/TiO2 photocatalysts exhibit highly efficient visible light photocatalytic activity. Though there have been extensive investigations on AgI/TiO2 photocatalysts, study on their stablity is still very limited. So in this paper, such a study is designed and conducted. AgI/TiO2 nanostructured photocatalysts were prepared and separately immersed in HCl solutions, DI water and NaOH solutions with pH value of 0, 4, 7, 10 and 14, respectively. X-ray diffraction and diffusive reflectance UV-vis spectroscopy analyses reveal that the immersion in acidic solutions led to the formation of AgCl and a blue shifting to 450nm for the absorption edge of AgI/TiO2, while the alkaline treatment had no significant effect on the composite structure of AgI/TiO2 or on the UV-vis absorption edge. Photocatalytic tests show that immersion in acidic solutions had more significant influence on AgI/TiO2 photocatalytic degradation of methyl orange (MO). At pH = 4, photocatalytic efficiency was dropped nearly 30%. At pH = 10, no significant change was observed. AgI/TiO2 nanostructured photocatalysts have thus been found to display a higher stability in alkaline solutions than in acidic solutions.

Effect of Different Washing Treatments on the Formation of Titanate Nanotubes

2010 ◽  
Vol 663-665 ◽  
pp. 1247-1251 ◽  
Author(s):  
Cheng Yan Liu ◽  
Lei Miao ◽  
Rong Huang ◽  
Sakae Tanemura
Keyword(s):  
Aqueous Solution ◽  
Driving Force ◽  
Deionized Water ◽  
Sodium Ion ◽  
Titanate Nanotubes ◽  
Acidic Solutions ◽  
Ph Values ◽  
Acid Washing ◽  
Almost All ◽  
Titanate Nanosheets

Titanate nanotubes were successfully synthesized by means of an alkaline hydrothermal method and further appropriate post-treatments. The effect of different washing treatments on the formation of titanate nanotubes were systematically studied in this paper. It was found that the washing treatments play an important role in the formation of nanotubes. Treating with 0.1M NaCl aqueous solution mainly resulted in titanate nanosheets while treating with deionized water or 0.1M HCl aqueous solution (1 time, PH>7) can obtain highly crystallized titanate nanotubes. Furthermore, if the PH values of solutions after acid washing processes were below 7, trace of nanotubes can be found but almost all of them were damaged. On the basis of all the present experimental results, we can conclude that titanate nanotubes can be prepared as long as the driving force induced by the imbalance of sodium ion (Na+) concentration on two different sides of nanosheets was appropriate, and meanwhile they were instable in acidic solutions.

scholarly journals Influence of pH on the Electropolymerisation of 2-Aminophenol and 2-Aminobenzyl Alcohol

2015 ◽  
Vol 18 (1) ◽  
pp. 037-041
Author(s):  
Ahmad S. Barham
Keyword(s):  
Aqueous Solutions ◽  
Benzene Ring ◽  
Polymer Films ◽  
Resonance Effect ◽  
Microelectrode Arrays ◽  
Hydroxyl Group ◽  
Amine Group ◽  
Acidic Solutions ◽  
Ph Values ◽  
Influence Of Ph

The electrochemical oxidation and polymerisation of 2-aminophenol and 2-aminobenzyl alcohol in aqueous solutions of different pH values has been studied. Polymer films of the studied monomers on gold electrodes were synthesized. The behaviour of both monomers is quite different, illustrating the resonance effect of the hydroxyl group being bound directly to the benzene ring for 2-aminophenol. For each compound it is shown that oxidation in acidic solutions is most difficult due to the protonation of the amine group. These polymer films can be used for applications such as corrosion protection and as structures from which textured electrodes, microelectrode arrays for example, can be generated.

Sign in / Sign up

Export Citation Format

Share Document