Advanced Materials Research Vols. 233-235

Abstract: This paper discussed the bleaching process with chlorine dioxide on cotton fabric. Tests of the whiteness, capillary effect, and strength were made and the best bleaching process with chlorine dioxide was determined. Studies showed that compared with the conventional bleaching process of hydrogen peroxide, the whiteness and strength of cotton fabric treated with chlorine dioxide were higher and the capillary values was similar. Chlorine dioxide can find its good application because of its good properties and low pollution.

Abstract: 430 stainless steel is used as raw material and pickling in HCl-based electrolytes is adopted, and the effect of oxidation agent on removal behavior of the oxide layer on stainless steel is systematically studied; study found that the oxide layer of stainless steel after heat treatment in the lab is composed of iron oxide and chromium oxide, and outer oxide layer has dense structure while inner layer has multihole structure; with the increasing oxidation agent addition, corrosion potential of stainless steel after heat treatment increased; under 1.0% oxidation agent addtion condition, only few inner oxide remained and removal tendency of oxide layer is obvious when pickled for 200s; oxide on surface totally got removed, and a smooth surface obtained after pickled for 400s.

Abstract: Electrodeionization(EDI) is an electro-membrane process with high efficiency for deep desalinating, where water dissociation mechanism occurring on the surface of ion exchange membranes and resins typically exsits and acts. But when used to treat heavy metal-containing solutions such as effluents from the electronic industry, the EDI will suffer from metal-hydroxides precipitation which would destroy the separation process irreversible. With the primary aim to solve that problem, an electrodeionization process coupled with bipolar membrane (BMEDI) was developed together with a preacidification method. The effects of separating and concentrating heavy metal ions by the BMEDI were studied with NiSO₄ solution containing 24 mg×L^-1 Ni²⁺ ions. The results suggested that, the nickel-concentration in the dilute products were both below the analysis limit at constant current densities of 40 mA·cm^-2 and 10 mA·cm^-2, while a concentration factor of 31 was achieved at 40 mA·cm^-2. In addition, no Ni(OH)₂ precipitation was found in all the compartments throughout the experiments, which provide a guarantee of good stability for long-time operation.

Abstract: A new type composite catalyst of V₂O₅ comprising Co-Mo/V₂O₅ was prepared by immersion method and characterized by XRD. The characteristic peaks of CoMoO₄(2θ=28.51°) and CoMoO₃(2θ=18.06 °)are both observed in the XRD patterns of Co-Mo/V₂O₅(5%, 20%) catalysts. The oxidation of cyclohexane with hydrogen peroxide was used as a probe reaction to investigate the effects of some conditions, such the sort and volume of solvent, catalyst amount, oxidant amount, reaction temperature and time, on reaction. Using 0.5 ml of cyclohexane, 10 ml of acetonitrile, 3 ml of hydrogen peroxide and 0.03 g of catalyst at a reaction temperature of 55°C for 3 h, the cyclohexane conversion was 32.3% and the total selectivity to cyclohexanol and cyclohexanone was 100%.

Abstract: Cake fouling mechanism was studied for membrane bioreactor (MBR) treatment of synthetic coke wastewater. Cake fouling characteristics of the aerobic activated sludge from MBR was investigated. The experimental results demonstrated that the cake governing equation fit the entire cake microfiltration (MF) process while cake fouling model was applicable to simulate the decrease in permeability and was used to predict the cake fouling development for both PVDF and PP MF membranes. Based on four-step development progresses, cake formation mechanism had been depicted with the increasing of TMP and the reduction of the cake porosity ratio. In addition, the comparison experiments under different operation modes were performed to further analyze the cake governing mechanism for MBR filtration.

Abstract: An efficiency of rare earth (europium, Eu) removal from aqueous solutions by polymer enhanced ultrafiltration (PEUF) process was investigated using two water-soluble polymers polyacrylic acid (PAA) and polyethylenimine (PEI). The effects of loading ratios of Eu to PAA or PEI, pH of solution and the added salt on Eu removal were evaluated. It was shown that the binding capacities for PAA and PEI to Eu ions were 0.8g Eu/g PAA and 0.5g Eu/g PEI, respectively. Eu ion rejection R decreased significantly at a low pH compared to the results at high pH, regardless of using PAA or PEI. Compared to the PAA case, PEI enhanced UF was more sensitive with changing pH. The effect of the added salt was slightly weak at pH 4-5.At the decomplexation stage, when permeate volume was equal to three times than that of the retentate, Eu removal efficiency (X) of Eu-PAA enhanced UF was 79.5% while that of Eu-PEI enhanced UF was 76.1%, and the polymer PAA and PEI could be recovered more than 97% and 93%, respectively. Eu in the retentate could be extracted effectively and the purified PAA and PEI solution were obtained. The recovered PAA and PEI solution was same as the fresh PAA and PEI solution in PEUF processes carried out by using the recovery recovered PAA and PEI as complex agents.

Abstract: The prepared composite photocatalyst H3PW12O40/TiO2 was synthesized by sol-gel impregnation method and characterized by scanning electron microscope(SEM), energy-dispersive X-ray spectroscopy(EDS), Fourier transform infrared(FT-IR), X-ray diffraction(XRD), UV-vis diffuse reflectance spectrum(DRS) to investigate its optical, physical and chemical properties. The results indicated that the modified catalyst was coated with P and W element, still have uniform anatase structure. Meanwhile, there is a chemical interaction exists between the Keggin unit and the surface of the titania matrix. Compared with original H4PW12O40 or TiO2 matrix, the adsorption threshold onset of the composite extended to the visible region. Effects of H3PW12O40/TiO2 dosage, pH value, initial p-NA concentration on the photocatalytic degradation of p-NA under 250W UV irradiation were investigated. The optimal H3PW12O40/TiO2 dosage and pH value for degradation of 10mg/L p-NA were o.6g/L and 3.0, respectively. The degradation rate of p-NA by H3PW12O40/TiO2 process could be fitted pseudo-first-order kinetics. Moreover, 66% degradation of p-NA was still observed in the 5th recycle experiment. Futhermore, 4-Aminophenol, Phenol, Hydroquinone, 4-Benzoquinone and other intermediate products were indentifieded by GC/MS and a possible reaction mechanism is proposed on the basis of all the information obtained from the analysis of FT-IR and the above intermediates.

Abstract: Ekor Kucing (Cabomba furcata) is a dominating water plant, which is rapidly proliferating in Lake Chini, Pahang, Malaysia. If left uncontrolled, the prevalence of this plant would threaten other plants, such as by inhibiting the growth of lotus (Nelumbo nicifera and Nympae lotus). It is also suspected as being a cause of pollution in Lake Chini. Steps to eradicate or control C. furcata plants first require a comprehensive study of its phytochemical content through methods of chemical screening, extraction/fractionation and analysis of individual compounds. Phytochemical screening carried out on the extracts detected flavonoid, saponin and alkaloid groups, but not triterpene and tannin. Different extraction yields were obtained from various plant parts, with the highest yield (%g/g sample) obtained before and after alkaloid fractionation were from the leaf (10.1%, 6.9%), followed by stem (9.6%, 4.5%) and flower (0.8%, 0.5%). Identification of alkaloids in C. furcata extracts by TLC showed the presence of nicotine, tomatine, thebaine and quinine.

Abstract: Brønsted acidic ionic liquids based on benzimidazolium cation was synthesized and employed as an efficient catalysts for the Michael addition reaction of indoles to α,β-unsaturated ketones under mild conditions to afford the corresponding conjugate addition products in high yields (90%-98%). The catalyst 1-butyl-3-(3-sulfopropyl)benzimidazolium p-toluenesulfonate ([PSbbim][p-CH₃PhSO₃]) could be reused at least three times without a noticeably decrease in its activity.

Abstract: 304 stainless steel is deemed an indispensable material in the industry. In many instances, the surface of the production equipment needs to be treated for low-corrosion passivation, lower surface roughness, good degree of finish and cleanliness. The process characteristics of pulse electrochemical polishing meet these requirements well. The current study investigates the effects of the major processing parameters on the surface reflectivity and the surface metallography. The electrolyte with 29.4% water content and a ratio between H₂SO₄ and H₃PO₄ of 2 and 4 has been proven to be successful, showing no corrosion pitting points on the specimen surface. The electrolyte temperature of 50~55°C, the pulse duty ratio of 33~50% and the electrical current density of 50 to 55A/dm² are found to be optimal. The addition of 2.4% glycerin and 2.2% glucose provides a very fine surface, surface reflectivity of stainless steel from 18% improve 89%.