Advanced Materials Research Vols. 287-290

Abstract: The photochemical degradation mechanisms of an azo dye Direct Red 4BS and Methyl Orange on hematite in the presence of H₂O₂ were investigated. The decolorization of azo dyes was attributed to the forming surface complex between specific bond of the dyes and hematite, which facilitate the electron transfer from hematite to azo bond. No mineralization of azo dyes occurred in the presence of visible irradiation, only chromogenic group destroyed in the photo-chemical reaction process. Surface complex between azo dyes and hematite will be destroyed under alkaline solution which suggested the active site or the formed surface complex had been destroyed by OH^–. Chemical adsorption of the azo dyes on hematite was critical factor which affect the decolorization efficiency of the photoreaction.

Abstract: Fixed-bed column studies for the removal of Ag(Ⅰ) and Cr(Ⅲ) from individual aqueous solutions using puffed rice husk were investigated in this work. The experiments were conducted to study the effect of important column parameters such as bed height, feed flow rate and feed initial concentration of solution. It was found that increasing bed depth yielded longer service time while increase in influent concentration and flow rate resulted in faster breakthrough. Bed Depth Service Time (BDST) model was applied to analyze the experimental data and the model parameters were evaluated. Good agreement of the experimental breakthrough curves with the model predictions was observed.

Abstract: A new extractant,N-benzothiazolylazo Butyl Imide(BBI),was synthesized and identified by elemental analysis,infrared spectrum and nuclear magnetic resonance (NMR).The extraction of Pd(II) using BBI diluted with CHCl₃ show high efficiency in 0-0.4M HCl medium.The dependence of the extraction percentages of Pd(II),Pt(IV)and base metal ions (Fe(III),Cu(II),and Zn(II)) on the HCl and BBI concentrations demonstrate that the idea condition for Pd(II) extraction is 0-0.4M HCl, 0.01-0.05M BBI.The stoichiometric ratio of Pd(II)-BBI complex is 1:2.The loading capacity of Pd(II) is about 0.5g/L using 0.1M BBI,which is comparable to that using DBSO.Complete stripping of Pd(II),Pt(IV) from loaded organic was proposed with 0.5M thiourea and 0.1M HCl.The Pd(II)-BBI-Cl complex has been characterized by elemental analysis,IR and ¹HNMR spectra.

Abstract: The solid solution series Ce_xZr(1-x-0.1)Y_0.1O₂ with various x values was prepared by the citric acid sol-gel method, using cerium and zirconium nitrides as precursors, respectively. The characterization results of the XRD, N₂ sorption measurements indicated that the physical properties of the solid solutions were significantly affected by the x values in Ce_xZr(1-x-0.1)Y_0.1O₂ and the calcination temperatures. These solid solutions can be used as catalyst for the direct synthesis of dimethyl carbonate from CH₃OH and CO₂. Results indicated that the catalytic activity for DMC synthesis was influenced by the structure of the solid solutions and the x values in Ce_xZr(1-x-0.1)Y_0.1O₂. The optimized Ce_0.5Zr_0.4Y_0.1O₂ with bimodal pore structure exhibited higher catalytic performance to DMC synthesis.

Abstract: Pb²⁺-SiO₂-TiO₂(Hereinafter referred to as PST) composite catalysts were prepared by sol-gel method from tetrabutyl titanate(TBOT),tetraetethyl orthosilicate(TEOS) and lead nitrate. Properties of the catalyst were characterized by means of XRD and FT-IR. In addition, the photocatalytic activities of Pb²⁺ doped silicon-titanium composite samples were evaluated by the result of photocatalytic degradation of methyl orange as a model reaction under simulated sunlight.The results have been showed that the optimum Pb²⁺ doping concentration is 1.5% and the optimum heat treatment temperature is 500°C. Photocatalytic degradation conversion of methyl orange (10 mg/L) on PST catalyst could reach above 90.0% under simulated sunlight for 3h.

Abstract: A series of Bi_xY_(2-x)O₃ photocatalysts were successfully prepared by a solid-state reaction and were subsequently characterized by powder X-ray diffraction, UV-vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS). The UV-vis diffuse reflectance spectra revealed that the Bi_xY_(2-x)O₃ samples absorbed light in the visible-light range (400-800 nm). The XPS results indicated that active oxygen species were generated on the Bi_1.8Y_0.2O₃ surface, which displayed a higher photocatalytic activity. When using photocatalytic degradation molasses fermentation wastewater as a model reaction, the Bi_1.8Y_0.2O₃ showed higher photocatalytic activity in comparison to Bi_0.2Y_1.8O₃ under visible-light irradiation.

Abstract: The water qualities of 5 waterplants were studied by investigating the total bacterial colony, oxygen consumption, free oxygen, and the turbidity. The results showed that the quality of water from ground water in the Industry North Road waterplant is better than those in Yuqing and Quehua which derived from the Yellow River indicated tipical seasonal chang. The quality of the outlet is mainly affected by the quality of raw water. The correlation analysis indicated that total number of colony did not significantly correlated to other indicators.

Abstract: The adsorption of p,p’-DDT onto expanded graphite (EG) in aqueous solutions was investigated under varying conditions of p,p’-DDT concentrations, adsorbent doses, pH, and contact time. The removal efficiency of p,p’-DDT from the aqueous solutions remained constant in a range of pH 2 to 10, and the thermodynamic data followed the type II adsorption isotherm characterized by a spontaneous process. At lower concentrations, adsorption equilibrium of p,p’-DDT onto EG was fitted to Freundlich isotherm. Dynamic modeling of the adsorption showed that the first order reversible kinetic model was held for the adsorption process within the range of experimental concentration. It was suggested that expanded graphite can be used for efficient removal of p,p’-DDT from water and wastewater.

Abstract: A new rare earth solid superacids catalyst SO₄^2-/TiO₂-SnO₂-Dy₂O₃ was prepared by coprecipitation-impregnating method, and the optimum preparation conditions were obtained. The physic- chemical properties of the catalyst was characterized by FTIR, TG-DTA, XRD and BET. The results showed the prepared catalyst is superacid with good thermal stability and high specific surface area. The sulfuric groups were proved to be chelated and bridgingly connected on the surface of the catalyst.

Abstract: A novel and efficient method was established to investigate isobutane/2-butene alkylation. In this method FT-IR spectroscopy was used to determine the presence of the composite ion (AlCuCl5-) in the composite ionic liquid (CIL). The trimethylpentane selectivity of the composite ionic liquid for isobutane/2-butene alkylation was also estimated by monitoring the shift of IR absorption bands in the range 1636–1685 cm-1. A detailed study of the alkylation of isobutane /2-butene in CIL media has been conducted using 1-alkyl-3-methylimidazolium halide/X aluminum chloride-y cuprous (I) chloride ([CnMIM]Cl/xAlCl3-yCuCl) encompassing various alkyl groups (n=4:B, butyl-, n=6:H, hexyl-, and n=8: O, octyl-)respectively. The ionic liquids showed higher selectivities of C8 as well as the TMP/DMH ratios in alkylates. The better catalytic performance of CIL can be attributed to the presence of the composite ion in it, and the catalytic performance of the chloroaluminate ionic liquid can be indicated by the 1685 cm^-1 band of FT-IR spectroscopy.