Papers by Keyword: Electrochemical Treatment

Abstract: During the last decade an increasing number of researchers focused on materials that have at least one dimension in the nanoscale range. That one dimension has immense impact on the physical and chemical properties of the materials, which is mainly due to the large surface to volume ratio. In order to modify the ratio of surface to volume, many shapes can be produced. Each shape is more useful in certain application than in others (e.g. nanowires are more used in sensors then other shapes and nanospheres are more used in medicine).In this paper, nickel nanowires were grown by electrochemical deposition into polycarbonate track etched (PCTE) membrane. The morphology and size of Ni NWs were examined using an Environmental Scanning Electron Microscopy equipped with energy dispersive X-ray spectroscopy.

Abstract: The degradation behavior and mechanism of biologically pretreated coking wastewater (BPCW) were investigated by means of a lab-scale electro-coagulation (EC) in static methods. The results showed that the percent COD and color removal can reach 80.5 % and 95.4 % respectively under the optimal conditions (initial pH of 8.0; reaction time of 30 min; current density of 14.0 mA/cm² and NaCl dosage 1.6 g/L).

Abstract: Abstract. In this study, the electrochemical treatment was used to block the leaching of alkali ions from concrete body, which would otherwise enhance the alkalinity of an aquatic environment and thus lead to a devastating contamination. The current density applied to the surface of concrete ranged 250, 500, 1000 mA/m2, and the duration of treatment was 1, 2, 4 weeks respectively. As a result, it was found that the treatment was effective in lowering the alkali leaching to an aquatic environment: an increase in the current density and duration of treatment resulted in a dramatic reduction of pH in the solution on the concrete surface. Its pH was reduced up to 8.33, whilst untreated concrete had a value of 12.91 in the pH. Simultaneously it is notable that the duration of treatment is a key shot to sustain the leachate blocking on the concrete surface. At the lower current density (250 mA/m2), the pH of the solution was eventually increased about 100 days after the completion of the treatment, while the pH at the highest current (1000 mA/m2) was mostly kept with no further increase.

Abstract: Electrochemical surface treatments of micro-arc oxidation (MAO) and following cathodic polarization were performed on zirconium (Zr) disks in this study to enhance the bioactivity of Zr. The surface oxide layers formed with electrochemical treatments on Zr disks were characterized using surface analyses; the calcium phosphate formation on the specimens after immersion in Hanks’ solution was evaluated. As a result, thick calcium phosphate layers formed on only Zr specimens that underwent both MAO treatment with a mixture of calcium glycerophosphate and magnesium acetate and subsequent cathodic polarization treatment with sodium sulfate solution, while no precipitate was observed without treatment. Thus, this technique was confirmed to be a promising method to improve the bioactivity of Zr.

Abstract: The Ti/SnO₂-Sb₂O₃/PbO₂ electrodes were prepared by thermal decomposition method and its application in the electrochemical degradation of a heteropolyaromatic dye, Methylene blue (MB), contained in simulated dye wastewater were investigated under mild conditions. The effects of pH, current density and electrolysis time on de-colorization efficiency were also studied. Chemical oxygen demand (COD) was selected as another parameter to evaluate the efficiency of this degradation method on treatment of MB wastewater. The results revealed that when initial pH was 6.0, current density was 50 mA·cm², electrolysis time was 60 min, Na₂SO₄ as electrolyte and its concentration was 3.0 g·dm³, the de-colorization and COD removal efficiency can reach 89.9% and 71.7%, respectively.

Abstract: The various methods for improving chloride penetration resistance in the reinforced concrete have been developed. Among the related general ways, using of corrosion inhibitor became very common. Therefore, in this study, in order to comprehend performance of corrosion inhibitor, the experiment study was conducted about corrosion characteristic of 3 steps(0.0, norm 1/2, norm) compared to organic corrosion inhibitor standard use of liquid and molar 3 steps(0.0, 0.3, 0.6%) of Chloride by added amount of inorganic corrosion inhibitor by the corrosion inhibitor types about 2.4kg/m³, 4.8kg/m³ based on Chloride ion content 1.2kg/m³ for service life prediction of concrete structure by using Poteniostat. As results, in the case of inorganic nitrous acid corrosion inhibitor, it was confirmed that anti-corrosive performance of Chloride ion content 1.2kg/m³ by corrosion Ecorr -0.30V in more than molar ratio 0.3%, and it also was confirmed that anti-corrosive performance of 2.4kg/m³, 4.8kg/m³ in more than molar ratio 0.6%. In addition, the excellent anti-corrosive performance of organic corrosion inhibitor was shown in 1/2(0.42kg/m³) of norm regardless of Chloride ion content, and it can be seen that absorption types organic corrosion inhibitor has excellent anti-corrosive performance compared to the inorganic nitrous acid corrosion inhibitor by the added amount of corrosion inhibitor.

Abstract: The electrochemical treatment of wastewater containing 2, 4, 6-trichlorophenol has been carried out experimentally with synthetic boron-doped diamond (BDD) thin film electrodes. Removal rate of COD, instant current efficiency (ICE) and energy consumption were investigated under different current density. The influence of supporting media is reported, which plays an important role in determining the global oxidation rate. The oxidative chloride is stronger than peroxodisulphate. The electrochemical characteristics of boron-doped diamond electrodes were investigated in comparison with active coating Ti substrate anode (ACT). The experimental results show that BDD is markedly superior to ACT due to its different absorption properties.

Abstract: The purpose of this study is to develop non nitric acid desmut to cope with environment regulation and at the same time, to obtain the effect comparable to nitric acid in removing smut. For this, some desmut solutions were produced adding 2~3 chemical reagents to basic components such as peroxide, ammonium group, ferric group compounds and acid. And, electrochemical treatment was tried to remove ammoniacal nitrogen(NH3-N) in desmut solution after desmut treatment. Consequently, we could gain smut-removing ratio of 90% using the solution mixed with peroxide, ammonium group, ferric group compounds and sulfuric acid at 35°C for 70 seconds, and the ratio is almost the same with that using nitric acid type desmut solution. In this work, most nitrogen(T-N) was confirmed to be ammoniacal nitrogen(NH3-N). In addition, we succeeded in controlling ammonia-nitrogen below 60 ppm corresponding to environment regulation by electrochemical treatment in the wastewater.

Abstract: CVD (chemical vapor deposition) SiC continuous fiber is used as reinforcement of metal matrix composites because of its high strength, high stiffness and elevated temperature stability. In this work, anodic oxidation method was used to treat the surface of carbon coated SiC fiber. Then the surface of treated fiber was compared with untreated one by scan electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). SiC was detected on the surface of untreated carbon-rich coating. It is proved by XPS that SiC was transformed into SiO2 after treatment. About 100~200nm thick oxidation layer was detected on the surface of carbon-rich coating and the structure of double coatings formed. Because the surface of fiber became smooth and the tensile stress on it was relaxed after treatment, the tensile strength of fiber was improved by 8%~20% average and the dispersing ratio of it was reduced.

Abstract: It is well known that the Al-Fe system intermetallic compound particles on the aluminum and its alloys are detrimental to the corrosion for aluminum materials. Trial and error efforts reveal that Al3Fe intermetallic compound particles exposed on aluminum are preferentially and selectively removed by electrochemically treatment in cathodic current. These treatment combined by two steps: the first step is selective dissolution of aluminum component in the Al3Fe intermetallic compound by electrochemical reaction. The second step is intensive removal of the iron-enriched intermetallic particles on which vigorous hydrogen bubbling has been took place. The electrochemical measurement and surface observation show that the aluminum and its alloys with free intermetallic compound particles treated by aboves have excellent corrosion resistance in a NaCl solution. It is also found that the intermetallic compound-free surface is preferable for the pretreatment surface for the surface finishing.