植物镉耐性/富集基因的筛选方法

植物耐受/富集镉（Cd）是一个复杂的过程,涉及转运蛋白家族、螯合蛋白家族、抗氧化系统等多个方面的参与。文章综述了植物Cd耐性/富集基因的筛选方法,包括抗性表达文库、Cd抗性突变体的图位克隆、基因差异表达、电子克隆。筛选Cd抗性植物cDNA酵母表达文库可鉴定与金属束缚、隔离及外排相关的膜转运蛋白;筛选重金属敏感拟南芥突变体和图位克隆突变基因可鉴定与谷胱甘肽和植物螯合肽合成相关的酶;第二代测序技术、基因差异表达分析则是鉴定Cd响应基因以及揭示金属型植物与非耐性植物表型差异分子基础的有效方法;电子克隆也被应用在模式植物中鉴定重金属转运蛋白家族的编码基因。在此基础上,简述了Cd耐性/富集基因在改良植物Cd耐性或富集上的应用。     

市政污泥热解过程中重金属迁移特性及环境效应评估

以昆明某市政污泥为原料,研究生物炭制备过程中重金属Fe、Zn、Mn和Ni的迁移特性,并基于其潜在环境风险确定污泥基生物炭制备的最佳热解温度.本实验选择总量较高的4种重金属Fe、Zn、Mn和Ni,采用BCR提取法测定不同热解温度下4种重金属的形态和含量变化,得到各金属的形态分布变化规律和迁移路径,利用潜在生态风险指数（PERI）和风险评估代码（RAC）对污泥基生物炭进行环境风险评估.结果表明,4种金属的易挥发程度排序为Zn > Mn > Fe > Ni,4种金属形态分布情况和变化规律各不相同,但迁移路径具有共通性.在低温热解阶段,不稳定形态向稳定形态转化;随着温度的升高,可氧化态和残渣态逐步分解破碎,部分逸散到大气中,部分形成可还原态.在环境风险评估方面,高温条件（>500℃）下制备的生物炭环境风险较低,500℃制备的生物炭经济性最好.     

典型山区燃煤型电厂周边土壤重金属形态特征及污染评价

为了揭示毕节金沙电厂周边土壤重金属（Hg、As、Cd、Cr、Cu、Pb和Zn）污染状况,在电厂周围采集了32个土壤表层样品,采用改进的BCR连续提取法进行形态分析,并以Hakanson潜在生态危害指数法、改性灰色聚类法及风险评估编码法（RAC）进行生态风险评估.结果表明：重金属含量变化具有一定的空间变异结构和空间分布特征,除了Cd和Cr的含量平均值低于贵州省土壤平均背景值外,其余重金属含量的平均值均大于该背景值.土壤中的大部分重金属主要以残渣态形式存在,而Cd主要以酸可提取态和可还原态存在,具有很强的环境危害.相关性分析结果显示,Hg与As、Cd表现为极显著相关,而Zn与其余重金属元素相关性都较弱.生态风险评价得出7种重金属的生态风险大小顺序为Cd > Hg > As > Cu > Pb > Zn > Cr,综合潜在生态风险指数（RI）平均值为129.72,处于中等生态风险.通过改性灰色聚类法对土壤重金属污染进行分析评价,表明电厂西面污染明显高于东面,且Hg和Cd为主要污染物;由风险评估编码法得出元素Cd有效态占18.17%,对环境构成中等风险等级,元素Cr和Zn对环境的危害处于低风险状态,元素Hg、Pb、As和Cu处于无风险状态.综合以上研究结果,金沙电厂土壤受到不同程度的重金属污染,应特别重视Hg和Cd这两种重金属污染的治理.     

Removal of Eu3+, Ce3+, Sr2+, and Cs+ ions from radioactive waste solutions by modified activated carbon prepared from coconut shells

As a biomass agricultural waste material, coconut shells were used for the preparation of high-quality modified activated carbon. Chemical modification of the surface of the prepared activated carbon is done by oxidation using H₂O₂ and HNO₃, respectively. The surface area and pore volume of the coconut shells activated carbon are increased by the chemical modification, and followingly the removal of the metals is improved. The structural morphology and composition of the modified activated carbon coconut shells (MACCS) were evaluated by Fourier transform infrared (FTIR) spectra, thermogravimetric analysis–differential thermal analysis (TGA-DTA), scanning electron microscope (SEM), X-ray diffraction (XRD), surface area analysis (SAA), X-ray fluorescence (XRF), and carbon, hydrogen, nitrogen, and sulfur (CHNS) elemental analysis. The prepared MACCS has reasonably good chemical stability. The influence of solution pH, contact time, adsorbent dosage, adsorption temperature, initial metal concentrations, and interfering ions on the adsorption performance of the investigated ions onto the prepared sorbent was examined by a batch method. The selectivity sequence for sorption of Eu³⁺, Ce³⁺, Sr²⁺, and Cs⁺ ions on MACCS was found to be Eu^3+?>?Ce^3+?>?Sr^2+?>?Cs⁺. The saturation capacities of MACCS for the studied metal ions were found to be 136.84, 85.55, 69.85, and 60.00?mg?g^?1 for Eu³⁺, Ce³⁺, Sr²⁺, and Cs⁺ ions, respectively. The thermodynamic parameters, ΔH°, ΔS°, and ΔG° were also evaluated.     

Preconcentration of cadmium and copper ions on magnetic core–shell nanoparticles for determination by flame atomic absorption

Magnetic core–shell nanoparticles modified by (3-aminopropyl) trimethoxy silane were prepared and used as adsorbent for the extraction and preconcentration of cadmium and copper ions. The ions were desorbed with nitric acid followed by determination with flame atomic absorption spectrometry. The extraction conditions were investigated systematically. The method was applied for the determination of Cd(II) and Cu(II) ions in different water samples. The accuracy was also evaluated through analysis of certified reference material.     

The prediction of adsorption isotherms of ester vapors on hypercrosslinked polymeric adsorbent

Adsorption isotherms of methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and ethyl propionate on hypercrosslinked polymeric resin (ND- 100) were measured at 303K, 318K and 333K,respectively, and well fitted by Dubinin–Astakhov (DA) equation. The plots of the adsorbed volume (q _v ) versus the adsorption potential (ε) at three different temperatures all fell basically onto one single curve for every ester. A predicted model based on DA equation was obtained on the basis of adsorption equilibrium data of methyl acetate, ethyl acetate and ethyl propionate at 318K. The model equation successfully predicted the adsorption isotherms of methyl acetate, ethyl acetate and ethyl propionate on ND-100 at 303K, and 333K, and also gave accurate predictive results for adsorption isotherms of the other two ester compounds (propyl acetate and isopropyl acetate) on ND-100 at 303K, 318K and 333K. The results proved the effectiveness of DA model for predicting the adsorption isotherms of ester compounds onto ND-100. In addition, the relationship between physico-chemical properties of adsorbates and their adsorption properties was also investigated. The results showed that molecular weight, molar volume and molar polarizability had good linear correlations with the parameter E (which represents adsorption characteristic energy) of DA equation.     

改性核桃壳对石油烃类物质的吸附试验研究

为了研究改性制备核桃壳对石油烃吸附程度,以化学改性制备核桃壳为吸附剂,考察了溶液p H值、时间和温度对改性核桃壳吸附石油烃效果的影响。结果表明:当温度为298 K,p H为7.0,0.2 g改性核桃壳吸附处理100 m L浓度为60 mg/L的柴油溶液,80 min后吸附量最大,可达到12.57 mg/g。该吸附过程符合准二级动力学方程,其相关系数达到0.9999。在3种温度(298,308,318 K)条件下的吸附等温曲线更符合Freundlich模型。通过热力学计算证实,该吸附过程是吸热的、自发的过程,一定程度上的升温有助于石油烃的吸附。     

改性纤维素负载零价铁去除三氯甲烷的研究

以接枝改性后的纤维素SCB为载体,采用液相还原法制备改性纤维素负载零价铁吸附剂ZVI-SCB,利用XRD、ESEM进行表征,并研究其对三氯甲烷(TCM)的去除性能.系统探讨了不同材料、ZVI-SCB投加量、TCM的初始质量浓度、pH值和氯离子质量浓度对TCM去除性能的影响.在ZVI-SCB投加量为5g/L,TCM的初始质量浓度为36.7mg/L,pH值为3.1时,TCM的去除率高达84.4%.采用准一级方程和准二级方程对ZVI-SCB去除TCM的过程进行拟合,准二级动力学方程相关系数R的范围为0.996~0.999,证明ZVI-SCB对TCM的去除过程符合二级动力学模型.     

改性黏土絮凝海洋原甲藻对水体中氮、磷的影响研究

通过对比研究典型有害微藻海洋原甲藻(Prorocentrum micans Ehrenberg)自然消亡(A1组)及改性黏土絮凝(A2组)两种体系,考察两体系中氮、磷等主要水质因子的变化情况.结果表明,改性黏土能有效去除P. micans并影响其后期生长状态,0.4g/L改性黏土添加3.5h后去除率可达60%以上,且藻密度无二次增长.改性黏土絮凝藻华过程中能有效去除水体营养元素, A2组DIP和DIN较A1组分别降低85%和35%.另外,添加改性黏土对水体有机氮、磷影响值得关注,第33d A2组TON和TOP较A1组分别减少约120, 6μmol/L. 改性黏土对有机氮、磷存在一定的埋存保护作用,通过吸附絮凝、螯合等作用使有机氮、磷脱离水体系统,而自然消亡体系中的微藻消亡后将通过分解、矿化等过程快速进入水体参与再循环.该研究系统阐述了改性黏土絮凝P. micans对水体营养环境的影响,以期为现场治理提供理论支持.     

聚硫代酰胺修饰活性炭对Au(Ⅲ)的选择性吸附效果与机制

通过在活性炭(AC)上原位合成聚硫代酰胺(PTA),成功制备了一种聚硫代酰胺修饰的活性炭基吸附材料(AC-PTA),研究其对废水中三价金[Au(Ⅲ)]的选择性吸附效果及机制.结果表明,AC-PTA在较宽的pH范围(＜5.0)内对多金属离子共存溶液中的Au(Ⅲ)表现出优异的选择性吸附性能,Au(Ⅲ)的剩余浓度小于0.1m...