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771.
纳米二氧化钛改性聚醚砜超滤膜 总被引:1,自引:0,他引:1
采用液-固相转化法,以聚醚砜(PES)、聚乙烯吡咯烷酮(PVP)和N,N-二甲基乙酰胺(DMAc)为原料制备PES超滤膜,并添加纳米TiO_2制备改性PES超滤膜.纳米TiO_2可降低制膜液的黏度,提高膜的亲水性能和抗污染性能.在PES质量分数为18%、PVP质量分数为12%、TiO_2质量分数为5.3%、DMAc质量分数为64.7%的条件下制备的改性PES超滤膜性能最佳,在24 ℃、0.2 Mpa操作条件下,膜的纯水通量为80.31 mL/ (cm~2·h), 截留率达99.16%.改性PES超滤膜过滤出水水质达到GB/T18920-2002<城市污水再生利用城市杂用水水质>标准.清洗后,未改性PES超滤膜的膜通量恢复率为68.08%,改性PES超滤膜的膜通量恢复率为85.31%. 相似文献
772.
Xiangyang Bi Xinbin Feng Yuangen Yang Grace P.Y. Shin Guangle Qiu Taoze Liu 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):834-839
Plants grown in contaminated areas may accumulate trace metals to a toxic level via their roots and/or leaves. In the present study, we investigated the distribution and sources of Pb and Cd in maize plants (Zea mays L.) grown in a typical zinc smelting impacted area of southwestern China. Results showed that the smelting activities caused significantly elevated concentrations of Pb and Cd in the surrounding soils and maize plants. Pb isotope data revealed that the foliar uptake of atmospheric Pb was the dominant pathway for Pb to the leaf and grain tissues of maize, while Pb in the stalk and root tissues was mainly derived from root uptake. The ratio of Pb to Cd concentrations in the plants indicated that Cd had a different behavior from Pb, with most Cd in the maize plants coming from the soil via root uptake. 相似文献
773.
双氧水-高锰酸钾催化氧化降解地下水中硝基苯的效能与机理 总被引:1,自引:0,他引:1
应用双氧水-高锰酸钾(H2O2-KMnO4)催化氧化作用,对地下水中硝基苯(NB)的降解效果和作用机理进行了研究,探讨了H2O2、KMnO4的不同浓度、不同pH值以及地下水中比较有代表性的共存离子钙(Ca2+)、镁(Mg2+)、铜(Cu2+)、锌(Zn2+)、重碳酸根(HCO3-)、碳酸根(CO23-)等因素对NB氧化... 相似文献
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777.
Cadmium accumulation in and tolerance of rice (Oryza sativa L.) varieties with different rates of radial oxygen loss 总被引:1,自引:0,他引:1
Wang MY Chen AK Wong MH Qiu RL Cheng H Ye ZH 《Environmental pollution (Barking, Essex : 1987)》2011,159(6):1730-1736
Cadmium (Cd) uptake and tolerance were investigated among 20 rice cultivars based on a field experiment (1.2 mg Cd kg−1 in soil) and a soil pot trial (control, 100 mg Cd kg−1), and rates of radial oxygen loss (ROL) were measured under a deoxygenated solution. Significant differences were found among the cultivars in: (1) brown rice Cd concentrations (0.11-0.29 mg kg−1) in a field soil, (2) grain Cd tolerance (34-113%) and concentrations (2.1-6.5 mg kg−1) in a pot trial, and (3) rates of ROL (15-31 mmol O2 kg−1 root d.w. h−1). Target hazard quotients were calculated for the field experiment to assess potential Cd risk. Significant negative relationships were found between rates of ROL and concentrations of Cd in brown rice or straw under field and greenhouse conditions, indicating that rice cultivars with higher rates of ROL had higher capacities for limiting the transfer of Cd to rice and straw. 相似文献
778.
The Zn/Cd hyperaccumulator Arabis paniculata is able to tolerate high level of Zn and Cd. To clarify the molecular basis of Zn and Cd tolerance, proteomic approaches were applied to identify proteins involved in Zn and Cd stress response in A. paniculata. Plants were exposed to both low and high Zn or Cd levels for 10 d. Proteins of leaves in each treatment were separated by 2-DE (two-dimensional electrophoresis). Nineteen differentially-expressed proteins upon Zn treatments and 18 proteins upon Cd treatments were observed. Seventeen out of 19 of Zn-responsive proteins and 16 out of 18 of Cd-responsive proteins were identified using MALDI-TOF/TOF-MS (matrix-assisted laser desorption/ionization time of flight mass spectrometry). The most of identified proteins were known to function in energy metabolism, xenobiotic/antioxidant defense, cellular metabolism, protein metabolism, suggesting the responses of A. paniculata to Zn and Cd share similar pathway to certain extend. However, the different metal defense was also revealed between Zn and Cd treatment in A. paniculata. These results indicated that A. paniculata against to Zn stress mainly by enhancement of energy metabolism including auxin biosynthesis and protein metabolism to maintain plant growth and correct misfolded proteins. In the case of Cd, plants adopted antioxidative/xenobiotic defense and cellular metabolism to keep cellular redox homeostasis and metal-transportation under Cd stress. 相似文献
779.
Catalytic removal of bisphenol A from aqueous solution with hemoglobin immobilized on amino-modified magnetic nanoparticles as an enzyme catalyst was reported. The amino-modified magnetite nanoparticles were firstly prepared by the coprecipitation of Fe2+ and Fe3+ with NH3·H2O and then modified by 3-aminopropyltriethoxysilane. The immobilization process was optimized by examining enzyme concentration, glutaraldehyde concentration, cross-link time, and immobilization time. The optimum conditions for the removal of bisphenol A with immobilized hemoglobin were also investigated. Under the optimality conditions, the removal efficiency of bisphenol A was about 80.3%. The immobilization had a beneficial effect on the stability of hemoglobin and conversions of bisphenol A. According to the proposed breakdown pathway and the intermediates, the enzyme-catalytic removal of bisphenol A by the immobilized hemoglobin is considered to be an effective method. 相似文献
780.
To assess the toxic effects of phenanthrene on earthworms, we exposed Eisenia fetida to artificial soils supplemented with different concentrations (0.5, 2.5, 12.5, mgkg(-1) soil) of phenanthrene. The residual phenanthrene in the soil, the bioaccumulation of phenanthrene in earthworms, and the subsequent effects of phenanthrene on growth, anti-oxidant enzyme activities, and lipid peroxidation (LPO) were determined. The degradation rate of low concentrations of phenanthrene was faster than it was for higher concentrations, and the degradation half-life was 7.3d (0.5 mgkg(-1)). Bioaccumulation of phenanthrene in the earthworms decreased the phenanthrene concentration in soils, and phenanthrene content in the earthworms significantly increased with increasing initial soil concentrations. Phenanthrene had a significant effect on E. fetida growth, and the 14-d LC(50) was calculated as 40.67 mgkg(-1). Statistical analysis of the growth inhibition rate showed that the concentration and duration of exposure had significant effects on growth inhibition (p<0.001). Superoxide dismutase (SOD) activity increased at the beginning (2 and 7d) and decreased in the end (14 and 28 d). Catalase (CAT) activity in all treatments was inhibited from 1 to 14 d of exposure. However, no significant perturbations in malondialdehyde (MDA) content were noted between control and phenanthrene-treated earthworms except after 2d of exposure. These results revealed that bioaccumulation of phenanthrene in E. fetida caused concentration-dependent, sub-lethal toxicity. Growth and superoxide dismutase activity can be regarded as sensitive parameters for evaluating the toxicity of phenanthrene to earthworms. 相似文献