光还原时间对Ag/Bi2WO6光催化性能的影响

以五水硝酸铋和钨酸钠为原料水热法合成规整的三维花状直径约2.5—3.5μm的Bi_2WO_6微球,通过简单原位光还原过程合成了一系列Ag/Bi_2WO_6复合材料.紫外可见漫反射光谱表明Ag/Bi_2WO_6相比于纯Bi_2WO_6微球在可见光区域的光吸收边显著红移.在可见光照射下,对所制备的样品的光催化降解罗丹明B活性进行了评价.结果表明,Ag/Bi_2WO_6光催化活性随着光还原时间增加,先增加然后降低,光还原时间为20 min合成的Ag/Bi_2WO_6光催化活性最佳,40 min对罗丹明B的降解率已达到99.2%,反应速率常数为纯Bi_2WO_6的3.60倍.增强的光催化活性归因于银的引入导致光吸收范围的增加和光生载流子有效分离的协同效应.     

Physical origin for the nonlinear sorption of very hydrophobic organic chemicals in a membrane-like polymer film

Bioconcentration factor (BCF) is often assumed to be linearly associated with the octanol-water partition coefficient K(ow) for hydrophobic organic chemicals (HOCs). However, a large amount of data has suggested that the correlation between the logBCF and logK(ow) is curvilinear for HOCs. Similar curvilinear relationship has also been noticed for sorption of HOCs into poly(dimethyl)siloxane (PDMS), a polymer with cross-linked interior structures. So far no satisfactory explanation has been given to account for the deviation. In this study, we acquired additional experimental data to show that the curvilinear relationship between the log-based PDMS-coated fiber-water partition coefficient (logK(f)) and logK(ow) for polychlorinated biphenyls (PCBs) was indeed a reflection of the sorption process occurring in PDMS film other than experimental defects. The physical origin of the nonlinearity was pinpointed based on the theory of phase partitioning for HOCs. The linear relationship is observed if the solute molecule is considerably smaller than the size of a monomer unit of PDMS in that the Gibbs free energy required for cavity formation in PDMS is comparable to that in octanol. Higher free energy of cavity formation is needed to create sufficient free volume if the PCB molecular size is comparable to or larger than the monomer unit of PDMS. On the other hand, the free energy of cavity formation in octanol remains almost constant when this occurs, resulting in the observed curvilinear relationship. The proposed model adequately explains the observed data, as well as sheds lights into the physical origin of the steric interactions of large molecular size solute with the PDMS polymer network.     

Hyperaccumulating potential of Bidens pilosa L. for Cd and elucidation of its translocation behavior based on cell membrane permeability

Environmental Science and Pollution Research - Phytoremediation with the use of hyperaccumulating plant species to remove excess trace metals from contaminated soil and water is considered a...     

Immobilization of laccase by Cu2+ chelate affinity interaction on surface-modified magnetic silica particles and its use for the removal of 2,4-dichlorophenol

Magnetic Cu²⁺-chelated silica particles that employ polyacrylamide as a metal-chelating ligand were developed and used to immobilize laccase by coordination. The particles were characterized by scanning electron microscope and Fourier transform infrared spectroscopy. The preparation, the enzymatic properties of the immobilized laccase, and its catalytic capacity for 2,4-dichlorophenol degradation were systemically evaluated. The results showed that immobilized laccase exhibited maximum enzyme activity when it was immobilized for 1 h at a pH of 4.0 and a temperature of 5 °C. The optimum laccase dose was 20 mg/g of carrier. In comparison to free laccase, the immobilized laccase had better acid adaptability and thermal stability. Higher activity was observed for immobilized laccase at a pH range of 2.0 to 3.5 and temperatures from 25 to 40 °C. The immobilized laccase that was prepared for this work exhibited a good catalytic capacity for removing 2,4-dichlorophnol from aqueous solutions.     

水、土环境中锑污染与控制研究进展

随着工业的发展,锑作为一种具有潜在毒性和致癌性的类金属元素,已经较为广泛地存在于水体和土壤环境中,显现出不可忽视的环境问题,并引起国际科学界的高度关注。文章综述了锑在水体和土壤环境中的污染现状、化学行为形态以及污染控制方面的研究进展。由采矿业、制造业带来的锑水土污染问题较为突出,目前的处理处置方法难以满足需求。今后需要在锑的水土环境化学方面加强研究,探讨锑的迁移转化规律;高效吸附材料的开发制备也是一个重要内容;植物组合修复土壤中的锑污染将是一个重要的突破口。     

Fe0体系降解2,4-二氯酚的影响因素及其反应机理

采用铁屑、炉渣及河砂混合介质降解2,4-二氯酚(2,4 - DCP)模拟废水,研究铁屑粒径、铁屑投加量、铁屑与炉渣配比、pH值等因素对2,4- DCP脱氯效果的影响,探讨Feo体系降解2,4- DCP的反应机理.结果表明,铁屑粒径、铁屑投加量、铁屑与炉渣配比、pH对2,4- DCP脱氯效果均有显著影响,在铁屑粒径为2～5mm、不改变废水pH、铁屑与炉渣质量比为31:9条件下,Feo体系对2,4- DCP去除率高达97％.2,4- DCP经脱氯后主要产物为2-氯酚、4-氯酚和苯酚,反应后废水的可生化性明显提高,利于后续的生物处理.     

闽江福州段沉积物中多环芳烃的空间分布异质性研究

多环芳烃(PAHs)是环境中一类典型的持久性有机污染物,为探明PAHs在闽江福州段沉积物中的空间分布规律,采用传统统计学和地统计学相结合的方法对PAHs的空间异质性进行了研究.结果表明,PAHs含量变异系数(CV)在39%～90%之间,属于中等强度变异.3环PAHs含量的块金值与基台值之比[C0/(C+C0)]为0.307,具有中等强度的空间相关性,其余不同环数PAHs以及PAHs总量的C0/(C+C0)值都小于0.25,具有强烈的空间相关性.低环PAHs的分维数D值高于高环PAHs,空间异质性较高.3环及3环以上PAHs的Moran’s I系数随距离的增大而下降,且在0～25.0 km之间其空间自相关性随间隔距离的增大而减弱;而Moran’s I系数分析结果进一步说明了2环PAHs的空间变异特征的复杂性.受到水流影响,PAHs含量在南-北方向的半方差函数值与其它方向有所不同,但在东北-西南、东南-西北和东-西方向上的半方差函数值重合性较好,近似各向同性.用交叉验证法检验的结果表明,普通克里插值法能够很好地预测闽江福州段沉积物中PAHs的空间分布情况,PAHs含量沿水流流向大致呈下降的趋势.     

重金属污染综合防治实施进展与经验分析

重金属污染综合防治规划是"十二五"期间国家批复实施的第一个五年专项规划。《重金属污染综合防治"十二五"规划》实施三年多来,取得了积极成效。本文从重点行业综合防控、重点区域分类整治、重点企业责任落实、重点项目强力推进等方面,总结了《重金属污染综合防治"十二五"规划》实施进展、成效和主要经验,为《重金属污染综合防治"十二五"规划》后续实施和我国污染防治规划的制定与实施提供启发与借鉴。     

The association between maternal perfluoroalkyl substances exposure and early attention deficit hyperactivity disorder in children: a systematic review and meta-analysis

Environmental Science and Pollution Research - Some studies have shown that maternal exposure to perfluoroalkyl substances (PFASs) may be associated with early attention deficit hyperactivity...     

生物体内甲基汞检测方法的研究进展

无机汞离子容易在微生物的作用下转化为毒性很强的甲基汞,甲基汞具有亲脂性易在生物体内积累,并通过食物链传递对人体健康产生严重危害。因此研究和建立生物体内甲基汞含量快速、准确的检测方法至关重要。文中概述了生物体内甲基汞的主要检测技术和方法,其中气相色谱-原子荧光光谱法(GC-AFS)、高效液相色谱-电感耦合等离子体质谱联用法(HPLC-ICP/MS)和高效液相色谱-原子荧光光谱法(HPLCAFS)是三种最常用的检测方法。同时,介绍了处于研究阶段的化学荧光探针检测方法,并对生物体内甲基汞的检测技术发展方向进行了展望。