Rescue effects of Se-enriched rice on physiological and biochemical characteristics in cadmium poisoning mice

Environmental Science and Pollution Research - Cadmium (Cd) is an element injurious for human health and is possibly toxic to organisms at minor concentrations. While some of other trace metallic...     

Photoelectrochemical performance of birnessite films and photoelectrocatalytic activity toward oxidation of phenol

Birnessite films on fluorine-doped tin oxide(FTO) coated glass were prepared by cathodic reduction of aqueous KMnO_4. The deposited birnessite films were characterized with X-ray diffraction, Raman spectroscopy, scanning electron microscopy and atomic force microscopy.The photoelectrochemical activity of birnessite films was investigated and a remarkable photocurrent in response to visible light was observed in the presence of phenol, resulting from localized manganese d–d transitions. Based on this result, the photoelectrocatalytic oxidation of phenol was investigated. Compared with phenol degradation by the electrochemical oxidation process or photocatalysis separately, a synergetic photoelectrocatalytic degradation effect was observed in the presence of the birnessite film coated FTO electrode.Photoelectrocatalytic degradation ratios were influenced by film thickness and initial phenol concentrations. Phenol degradation with the thinnest birnessite film and initial phenol concentration of 10 mg/L showed the highest efficiency of 91.4% after 8 hr. Meanwhile, the kinetics of phenol removal was fit well by the pseudofirst-order kinetic model.     

Effects of synthesis methods on catalytic activities of CoOx–TiO2 for low-temperature NH3-SCR of NO

A series of cobalt doped TiO_2(Co-TiO_2) and Co Oxloaded TiO_2(Co/TiO_2) catalysts prepared by sol–gel and impregnation methods respectively were investigated on selective catalytic reduction with NH_3(NH_3-SCR) of NO. It was found that Co-TiO_2 catalyst showed more preferable catalytic activity at low temperature range. From characterization results of XRD,TEM, Raman and FT-IR, Co species were proved to be doped into TiO_2 lattice by replaced Ti atoms. After being characterized and analyzed by NH_3-TPD, PL, XPS, EPR and DRIFTS, it was found that the better NH_3-SCR activities of Co-TiO_2 catalysts, compared with Co/TiO_2 catalyst, were ascribed to the formation of more oxygen vacancies which further promoted the production of more superoxide ions(O-2). The superoxide ions were crucial for the formation of low temperature SCR reaction intermediates(NO-3) by reacting with adsorbed NO molecule. Therefore, these aspects were responsible for the higher low temperature NH_3-SCR activity of Co-TiO_2 catalysts.     

Opposite response of phosphorus sorption to pH and ionic strength: a comparative study in two different shallow lake sediments

Phosphorus (P) sediment sorption is regarded as the most important buffering process against P increases in overlying water. In this study, two shallow eutrophic sediments (Mei and Hua) with distinct compositions were selected to assess effects of pH (from 6 to 9) and ionic strength (IS) (0, 0.001, 0.01 and 0.1 M KCl) on P sorption. In Mei sediments, the P sorption decreased as pH increased (6.97–9.13), but it increased as IS increased over the pH range in question. These results could be attributed to the negatively charged surface of Mei sediments, as indicated by the salt titration curve, and the high cation exchange capacity (CEC). P sorption in Hua sediments was facilitated by a pH increase (6.12–7.49), but it was hindered by an IS increase. A reasonable explanation for this phenomenon is that calcium phosphate precipitates at high pHs and that Cl^? exchanges with P because the surface is weakly charged (small CEC). These results indicate that the sediment P sorption may have trends opposite to one another in relation to the salt change (e.g. drought and rainy season) in the lake water between the two sediments. These data provide additional support to explain P concentration variations in lakes.     

Preparation and Properties of Biodegradable Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blend with Epoxy-Functional Styrene Acrylic Copolymer as Reactive Agent

Poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT) are biodegradable polyesters and can be blended by twin-screw extrusion. Epoxy-functional styrene acrylic copolymer (ESA) was used as reactive agent for PLA/PBAT blends and the mechanical properties, phase morphology, thermal properties, melt properties, and melt rheological behaviors of the blends were investigated. During thermal extrusion, ESA was mainly a chain extender for the PLA matrix but had no evident reaction with PBAT. The great improvement in the toughness of PLA based blends was achieved by the addition of PBAT of no less than 15 wt% and that of ESA of no more than 0.5 wt%. Although SEM micrographs and the reduced deviation of the terminal slope of G′ and G″ indicated better compatibility and adhesion between the two phases, the blend with ESA was still a two-phase system as indicated in DSC curves. Rheological results reveal that the addition of ESA increased the storage modulus (G′), loss modulus (G″) and complex viscosity of the blend at nearly all frequencies. The melt strength and melt elasticity of the blend are improved by addition of ESA.     

原位帽封材料对水体中Pb(Ⅱ)与Cd(Ⅱ)静态吸附

用无纺布包裹珊瑚和丙烯酸树脂制成帽封材料,将底泥中重金属离子原位固定的同时吸附水体中的重金属离子pb2和Cd2.通过红外光谱,电镜扫描和火焰原子吸收仪器来分析该帽封材料的吸附性能.通过改变pH值,吸附剂投放量来检测其吸附效果.结果表明,该帽封材料在pH等于5的时候,Cd2最大吸附量达到434.67 mg/g,pb2+最大吸附量达到524.27 mg/g.pH和吸附剂量保持不变,随着底物浓度增加吸附量也增加;电镜扫描图和红外光谱图表明,该材料能很好地吸附重金属离子.     

EKC analysis for studying economic growth and environmental quality: a case study in China

Compared with the extensive research on the relationship between economic growth and environmental quality in developed countries, there is a paucity of an empirical research on studying the relation for developing countries. Based upon the Environmental Kuznets Curve (EKC) theory, this paper develops regression models for investigating the relationship between economic growth and environmental quality in China. The EKC analysis based on six pollution indices is illustrated with a case study in Jiaxing of Zhejiang, China.     

Characterization of solid waste disposed at Columbia Sanitary Landfill in Missouri.

Waste sorts were conducted during each of the four quarters (or seasons) of 1996 at the City of Columbia Sanitary Landfill. A detailed physical sampling protocol was outlined. Weight fractions of 32 waste components were quantified from all geographic areas that contribute to the Columbia Sanitary Landfill using a two-way stratification method, which accounted for variations in geographical regions and seasons. Comparisons of solid waste generated between locations and seasons were conducted at the 80% confidence level. The composition of the entire waste stream was 41% paper, 21% organic, 16% plastic, 6% metal, 3% glass and 13% other waste. Paper was the largest composition and glass was the smallest composition for all geographical regions. The result of this study was also compared with a 1987 Columbia, Missouri study conducted by EIERA (1987), with studies conducted in other states such as Minnesota, Wisconsin, Oregon and with national study conducted by the USEPA (USEPA 530-R-96-001, PB96-152 160. US Environmental Protection Agency, Office of Solid Waste, Washington, DC). The results of studies from other states are different from this study due to different local conditions, different methodologies and a different scope. There was a small (5%) increase in per capita weight from 1987 to 1996. The total per capita weight in the present study was 60% greater than the national per capita weight reported by the USEPA (1996) due to that the USEPA report excluded industrial, construction and certain commercial waste. The total per capita weight agrees with the national per capita weight for municipal waste reported by Tchobanoglous (1993), which included industrial, construction and commercial sources. The geographical and seasonal effects on the waste composition are evaluated and discussed. Statistical analysis indicates that waste characteristics are different among geographical regions and seasons. The potential for waste recovery and reduction is also discussed.