Gelled electrolyte is made at different temperatures based on liquid glass and sulfuric acid using two organic additives such as polyacrylamide and polyaniline. The antimony lead electrode is used to study the electrochemical properties of gelled electrolyte through cyclic voltammetry, electrochemical impedance and ionic conductivity determination. The results showed that the gelled electrolyte made at low temperature is in a more favorable form of gel than that at high temperature, the ability to extract water was also overcome. The resistance of charge transfer of lead electrodes operating in an gelled electrolyte environment is all lower than that in sulfuric acid (d = 1.26 g /cm 3 ), in which the presence of PANi together with PAM is recorded as the smallest. When the lead electrode was anodized, the simultaneous formation of PbO with PbSO4 did not appear due to the presence of PANi.
Gelled electrolyte is prepared from liquid glass and sulfuric acid with various specific weights in the presence of both gelling agents such as polyacrylamide and polyaniline. The antimony lead electrode is polarized by potentiodynamic method in gelled electrolyte compared with sulfuric acid solution (1.26 g/cm 3 ). The results found that not only the overpotential of gas evolution but also the polarization resistance depends on sample preparation conditions. The concentration of PAM at 0.55 wt% contributed to the shift of overpotential of oxygen release in the more positive side but made decreasing the hydrogen escape overpotential compared with H2SO4 solution (1.26 g/cm 3 ). It showed that the presence of PANi together with PAM did not improve the overpotential of oxygen release, but significantly inhibited the hydrogen evolution, although polarization resistance was approximately or smaller than that in H2SO4 solution (1.26 g/cm 3 ).
TiO2 nanotube arrays were prepared successfully by anodization of Ti foil in electrolyte containing 0.25 % NH4F, 5 % H2O and 94.75 % ethylene glycol and subsequently calcination at various temperatures from 300 to 600 o C in air. The crystalline structure and surface morphology of samples were determined by X-ray diffraction and SEM images, respectively. The effect of calcination temperature, anodization time and voltage on the photoelectrochemical property of TiO2 nanotube arrays had been investigated. Based on the obtained results, the highest photocurrent density of 5.29 mA/cm 2 was found for TiO2 nanotube arrays synthesized under conditions such as anodization time of 2 hours, anodization voltage of 40 V and calcinated at 500 o C.
INTRODUCTION Many adsorbents based on zeolite, bentonite or conducting polymer composites, etc. have been using for removal of heavy metal ions from waste water 1-3. In previous years, among conducting polymer, polyaniline (PANi) was mostly hybrided with agricultural waste or other materials to become composites using for environmental treatment because of their positive characteristics 4-6. Vietnam is a land of rice export so a huge amount of raw rice from which as an agricultural waste goes into environment. The aim of this work was preparation of composite based on raw rice with polyaniline for removing Pb 2+ and Cd 2+ ions from solution. The thermodynamic study and adsorption mechanisms of above metal ions were also studied. EXPERIMENTAL Preparation of materials: Composite was prepared by chemical polymerizarion owing to oxidation of aniline in hydrochloric acid medium at presence of raw rice and ammonium persulfate. The reaction was occurred in 18 h under continuously stirring at 1-5 ºC. After purification and changing it into emeraldine base (EB) by treatment with 0.5 M ammonia solution, it was filtrated and dried under vacuum condition at 50 ºC in 2 h and then kept in a sealed bottle for material properties and adsorption ability of heavy metal ions.
Mixed gel electrolytes were fabricated chemically at a temperature range of 2–5°C using some additives comparing with traditional electrolytes (1.26 g/cm3 H2SO4). The polyacrylamide (PAM) content is kept constant (0.2 wt%), while the propylene glycol (PPG) and nano fumed silica (NFS) contents varied. The material characteristics of samples were assessed by physical appearance observation, electrochemical measurements, and physicochemical methods. The results showed that a hard gel without separation of solutions was found in the case using a PAM/PPG/NFS ternary additive (0.2/0.1/0.6 wt%). The morphological structure (<50 nm) of mixed gel electrolytes was in the range of nanometer. The gas release on the PbSb electrode was strongly inhibited (92.2–93.7% for O2 and ∼55% for H2 at the 120th cycle), which will both contributes to reducing the pressure as well as limiting water loss in the sealed lead acid battery, compared with that in the sulfuric acid medium.
The research was conducted to evaluate the career adaptability of Khmer students after graduating from the Tra Vinh University. The results of the research come from an investigation of 152 Khmer students graduating from Tra Vinh University and 62 employers for whom Khmer students work showed that career adaptability of Khmer students is high; there was positive correlation between job adaptability of Khmer students and their attitudes, skills and knowledge, in which knowledge is the most influential factor to career adaptability of Khmer students.
The potentiostatic electrocoagulation (PEC) using iron (CT3 steel) for anode material was applied to removal of arsenic from well water. Some parameters such as potential, electrolysis time, and initial arsenic concentrations were varied for research in this article. The arsenic concentrations before and after PEC processing were analysed by AAS method. The mass of ferric hydroxide was calculated via Faraday's law. The results showed that the residual arsenic concentration in water samples from initial arsenic concentration until 800 ppb is smaller than that of WHO requirement (10 ppb). The adsorption of arsenic on ferric hydroxide fitted well into pseudo second-order kinetic equation, where its equilibrium adsorption capacity was linearly depended on the initial adsorption rate with R 2 of 0.9864. The Langmuir parameters N max and K L were 23.58 mg/g and 1060 L/mg with correlation constant (R 2 ) of 0.827, respectively.
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