利用乙二胺四乙酸淋洗修复重金属污染的土壤及其动力学

通过室内模拟试验,采用振荡淋洗的方法研究了乙二胺四乙酸(EDTA)浓度、pH、淋洗时间对重金属去除效果的影响.利用一级反应动力学模型对试验数据进行拟合,并测定了EDTA处理前后土壤中重金属形态的变化.结果表明,EDTA溶液在浓度为0.1mol.L-1、pH7、淋洗时间1d的条件下能达到对污染土壤重金属的最大去除率,去除率分别为Cd89.14%、Pb34.78%、Cu14.96%、Zn45.14%.模型拟合结果表明,Cd的质量转移系数最大,其次是Zn、Pb和Cu.说明在土壤淋洗过程中,Cd和Zn最先达到质量转移的平衡状态,然后是Pb和Cu.形态分级结果表明,EDTA能有效地去除交换态、碳酸盐结合态和氧化物结合态重金属,而对有机态和残余态部分重金属作用效果不明显.

两种螯合剂施用对污染土壤中叶用叶叶叶Cd富集的影响

为探讨螯合剂对植物吸收重金属的影响,采用盆栽试验,研究了螯合剂乙二胺四乙酸(EDTA)和柠檬酸(CA)对土壤重金属Cd的的的态的及的用的的的(Beta vulgaris var.cicla L)富集Cd能力的影响。结果表明:EDTA的添加比柠檬酸更显著增加了土壤重金属镉的的的态含量,同时提高了的用的的的茎的的富集系数和转运能力;施用螯合剂促进了Cd从的用的的的茎的菜部菜茎的的菜菜,的用的的的茎的含Cd量显著增加,EDTA的作用是柠檬酸的2~3倍。

淋(清)洗液中重金属回收与纯化材料的筛选

选用六种不同树脂,对含有单一及复合重金属(Cd、Pb)的水溶液和EDTA溶液进行了吸附和洗脱试验。结果表明:吸附和洗脱效果的重要影响因子是被吸附和洗脱的清(淋)洗液(或污水)的类型,而不是吸附和洗脱时间。在所试的六种树脂中,集最佳的吸附回收与洗脱纯化效果于一体的树脂是110H号(北京产)。

纳豆激酶分离纯化及性质研究

在实验室条件下,通过生理盐水浸提、硫酸铵分级沉淀、亲和层析、阴离子交换层析以及凝胶过滤层析,从纳豆中提取纳豆激酶。纯化后的纳豆激酶样品在SDS-PAGE银染中呈单一条带,纯度经密度扫描证实在95%以上,纤溶活性总收率达到52.9%。纳豆激酶性质研究结果发现,其最适pH值为7.5,对温度变化敏感,纤溶活性可被Ca2+,Ba2+,Na+等金属离子激活。纳豆激酶在水溶液中受EDTA强烈抑制及低离子强度条件下产生自我降解现象。

水稻重金属镉含量与土壤质量关系的研究

采用盆栽试验的方法,考察了土壤中不同浓度的镉对水稻生长、结实及重金属镉富集的影响以及镉在水稻植株的分布情况,并进一步研究了糙米(可食部位)对镉的富集量与土壤中镉总量和有效态镉含量的关系。研究表明:低浓度的镉对水稻生长稍有促进作用,高浓度的镉对其生长并没有明显的抑制作用;镉在水稻植株中总的分布趋势为根>茎>稻壳>糙米;用4种有效态提取剂(0.1 mol/L CaCl2、DTPA、0.05 mol/L EDTA和1 mol/L NH4OAc)浸提出的有效态镉的含量和土壤中镉总量与水稻糙米中镉含量均达到显著相关水平,并确定了它们的临界值分别为CaCl2-Cd=0.71 mg/kg,DTPA-Cd=1.34 mg/kg,EDTA-Cd=0.76 mg/kg,NH4OAc-Cd=0.77 mg/kg。

有机质对Cu~(2+)在棕壤及其各粒级微团聚体中吸附解吸特性的影响

采用平衡液吸附法和NH4AC、EDTA溶液解吸法,研究了有机质对Cu2+在棕壤及其各粒级微团聚体中(<10μm,10～50μm,50～250μm)的吸附解吸过程中的影响,为寻求有效控制土壤中Cu2+环境行为的对策措施提供理论支撑。研究结果表明,各粒级微团聚体中有机质对Cu2+的吸附能力随粒级的减小而增强,原土仅次于<10μm微团聚体。就吸附机制而言,去除有机质后的原土及其各粒级微团聚体在不同吸附机制控制下的吸附能力也有所变化,表现为:去除有机质后,棕壤及各粒级微团聚体对Cu2+的静电吸附能力增强,络合吸附能力和专性吸附的能力均有所降低。分析表明,原土及其不同粒级微团聚体对Cu2+的吸附能力及稳定性的差异,与其重要组成成分有机质有关。

Upconversion luminescence of Y2O3 : Er3+, Yb3+ nanoparticles prepared by a homogeneous precipitation method

Y2O3: Er3+, Yb3+ nanoparticles were synthesized by a homogeneous precipitation method without and with different concentrations of EDTA 2Na. Upconversion luminescence spectra of the samples were studied under 980 nm laser excitation. The results of XRD showed that the obtained Y2O3:Er3+,Yb3+ nanoparticles were of a cubic structure. The average crystallite sizes calculated were in the range of 28-40 nm. Green and red upconversion emission were observed, and attributed to H-2(11/2), S-4(3/2) -> I-4(15/2) and F-4(9/2) -> I-4(15/2) transitions of the Er3+ ion, respectively.

Red and green upconversion luminescence of Gd2O3 : Er3+, Yb3+ nanoparticles

Gd2O3:Er3+, Yb3+ nanoparticles have been synthesized by a homogeneous precipitation method with EDTA 2Na of two different concentrations. Upconversion luminescence spectra of the samples have been studied under 980 nm laser excitation. The results of XRD show that obtained Gd2O3:Er3+, Yb3+ nanoparticles are of a cubic structure. The average crystallite sizes could be calculated as 22 and 29 nm, respectively. The strong green and red upconversion emission were observed, and attributed to the H-2(11/2), S-4(3/2) -> I-4(15/2) and F-4(19/2) -> I-4(15/2) transitions of Er3+ ion, respectively.

An effective method for enhancing metal-ions' selectivity of ionic liquid-based extraction system: Adding water-soluble complexing agent

Selective extraction-separation of yttrium(Ill) from heavy lanthanides into 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF6]) containing Cyanex 923 was achieved by adding a water-soluble complexing agent (EDTA) to aqueous phase. The simple and environmentally benign complexing method was proved to be an effective strategy for enhancing the selectivity of [C(n)mim] [PF6]/[Tf2N]-based extraction system without increasing the loss of [C(n)mim](+). (c) 2007 Elsevier B.V. All rights reserved.

Preparation and application of single polyelectrolyte microcapsules possessing tunable autofluorescent properties

Autofluorescent single polyelectrolyte microcapsules, exemplified by poly-L-lysine (PLL), have been prepared through glutaraldehyde-mediated covalent layer-by-layer (LbL) assembly and subsequent core removal. CaCO3 microparticles were used as template cores for the LbL deposition and removed by treatment of ethylenediamine tetraacetic acid disodium salt (EDTA). The prepared microcapsules, without conjugating an exterior fluorochrome, exhibited evenly distributed fluorescence.

Synthesis and characterization of magnetite dodecahedron nanostructure by hydrothermal method

Magnetite dodecahedral nanocrystals were fabricated using ethlenediamine tetraacetic acid (EDTA)-mediated hydrothermal route. Scanning electron microscopy images displayed that the products were almost dodecahedrons. The length of two different ribs were about 300 and 200 nm, respectively. X-ray diffraction patterns showed that the products were the cubic inverse spinel structure. Fourier transform infrared spectrum directly provided evidence of the EDTA bound to a specific surface of the precipitated magnetic nanocrystal.

Hollow DNA/PLL microcapsules with tunable degradation property as efficient dual drug delivery vehicles by alpha-chymotrypsin degradation

Hollow deoxyribonucleic acid (DNA)/poly-L-lysine (PLL) capsules were successfully fabricated through a layer-by-layer (LbL) self-assembly of DNA and PLL on porous CaCO3 microparticles, followed by removal of templates with ethylenediamine tetraacetic acid disodium salt (EDTA). The enzymatic degradation of the capsules in the presence of alpha-chymotrypsin was explored. The higher the enzyme concentration, the higher is the degradation rate of hollow capsules. in addition, glutaric dialdehyde (GA) cross-linking was found to be another way to manipulate degradation rate of hollow capsules.

A facile pathway to prepare enzymatically degradable microcapsules with tunable capsule shell properties

Dextran sulfate (DS)/poly-L-lysine (PLL) microcapsules are fabricated by an in situ coacervation method using DS-doped CaCO3 microparticles as templates. Twinned superstructures or spherical CaCO3 microparticles are produced depending on DS concentration in the starting Solution. DS/PLL microcapsules with ellipsoidal or spherical outline are obtained after removal of templates in disodium ethylene diamine tetraacetate dehydrate (EDTA) without PLL. Their shell thickness and negative surface charges increase with the DS weight percentage in the templates. The surface potential of DS/PLL microcapsules.

Potassium-Lead-Switched G-Quadruplexes: A New Class of DNA Logic Gates

A cation-driven allosteric G-quadruplex DNAzyme (PW17) was utilized to devise a conceptually new class of DNA logic gate based on cation-tuned ligand binding and release. K+ favors the binding of hemin to parallel-stranded PW17, thereby promoting the DNAzyme activity, whereas Pb2+ induces PW17 to undergo a parallel-to-antiparallel conformation transition and thus drives hemin to release from the G-quadruplex, deactivating the DNAzyme. Such a K+-Pb2+ switched G-quadruplex, in fact, functions as a two-input INHIBIT logic gate. With the introduction of another input EDTA, this G-quadruplex can be further utilized to construct a reversibly operated IMPLICATION gate.

Shape-controllable synthesis and upconversion properties of lutetium fluoride (doped with Yb3+/Er3+) microcrystals by hydrothermal process

Lutetium fluorides with different compositions, crystal phases, and morphologies, such as beta-NaLuF4 hexagonal microprisms, microdisks, mirotubes, alpha-NaLuF4 submicrospheres, LuF3 octahedra, and NH4Lu2F7 icosahedra, prolate ellipsoids and spherical particles have been successfully synthesized via a facile hydrothermal route. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction, and photoluminescence spectra were used to characterize the samples. The intrinsic structural feature of lutetium fluorides, the solution pH values, F- sources, and organic additives (Cit(3-) and EDTA) account for the ultimate shape evolutions of the final products. The possible formation mechanisms for products with various architectures have been presented. Additionally, we investigated the upconversion luminescence properties of beta-NaLuF4: 20% Yb3+/2% Er3+ with different morphologies.