Fast and efficient aqueous arsenic removal by functionalized MIL-100(Fe)/rGO/δ-MnO2 ternary composites: Adsorption performance and mechanism

Because of its significant toxicological effects on the environment and human health,arsenic(As) is a major global issue.In this study,an Fe-based metal-organic framework(MOF)(Materials of Institut Lavoisier:MIL-100(Fe)) which was impregnated with reduced graphene oxide(rGO) by using a simple hydrothermal method and coated with birnessitetype manganese oxide(δ-MnO_2) using the one-pot reaction process(MIL-100(Fe)/rGO/δ-MnO_2 nanocomposites) was synthesized and applied successfully in As removal.The removal efficiency was rapid,the equilibrium was achieved in 40 min and 120 min for As(Ⅲ) and As(Ⅴ),respectively,at a level of 5 mg/L.The maximum adsorption capacities of As(Ⅲ) and As(Ⅴ) at pH 2 were 192.67 mg/g and 162.07 mg/g,respectively.The adsorbent revealed high stability in pH range 2-9 and saturated adsorbent can be fully regenerated at least five runs.The adsorption process can be described by the pseudo-second-order kinetic model and Langmuir monolayer adsorption.The adsorption mechanisms consisted of electrostatic interaction,oxidation and inner sphere surface complexation.     

砷、汞对植物毒性影响及其迁移富集效应探讨

介绍了自然环境中砷、汞的污染来源与污染现状,探讨了砷、汞对植物生长发育、光合作用和抗氧化能力的影响;为了缓解砷、汞对植物的毒害作用,可以添加新一代植物激素、营养元素和改良剂。分析发现,植物对不同浓度砷和汞的敏感程度并不相同,可利用特定植物的富集作用进行环境修复。当前研究主要集中于植物对砷、汞的吸收和转运生理机制,今后还需要加强对超积累植物分子基础的探索。     

Competitive Retention of Lead and Cadmium on an Agricultural Soil

Lead and cadmium contamination of an agricultural soil has been studied using batch and column experiments. Thermodynamics of theretention phenomena may be represented by a Langmuir isotherm foran aqueous metal concentration up to 100 mg L^-1. First order kinetics with respect to the solid phase yield good predictabilityfor both batch and column experiments. Kinetics and thermodynamics of lead retention predominate over those ofcadmium. As a consequence, lead is preferentially retainedand can even displace sorbed cadmium. In the event of anspill involving both metals, cadmium would move further inthe soil and its aqueous concentration downstream could beeven higher than that of the influent solution, increasingpotential risks. A two-region model has been used to fit all the experimental results. Satisfactory predictions for column experiments are obtained with parameters which are consistent with those obtained for the batch experiments, for which sorption is described by a Langmuir isotherm including competitive retention.     

珠江河口及近海水域中Cu的形态分布及其对藻类的生物毒性

对珠江河口及近海水域样品中Cu的总含量以及颗粒态、游离态Cu含量进行分析，结果发现，Cu的总浓度有随河口向外海递增的趋势，并非完全体现陆源性规律。说明研究水域中Cu不仅可能具有其他来源，同时在很大程度上受到沿岸上升流的影响。但是游离态Cu的分布却表现相反的规律，无论是游离态Cu的浓度还是游离态Cu在总Cu中所占的份额都自河口向外海随盐度的增加而降低。说明Cu的形态分布在更大程度上取决于水体的理化性质。本研究还逶过对不同盐度水样的杜氏藻培养后Cu吸收量的测定，即逶过Cu对藻类的生物有效性验证了Cu形态的分布规律。     

土壤中砷的原子荧光法测定

将土壤粉末均匀稳定地悬浮于0.15％～0.2％琼脂溶胶中,采用悬浮样品直接进样,氢化物发生—非色散原子荧光法,测定其砷含量。以柠檬酸—NaOH缓冲液控制试样pH4.7,测定As~(3+);以HCl、KI和抗坏血酸还原As~(5+)为As~(3+),测定总砷量;用差减法求得As~(5+)含量。方法应用于测定不同类型土壤时,相对标准偏差为1％～6％,回收率为85％～106％。     

EDTA和腐殖酸对铜在淡水藻(Scenedesmus subspicatus 86.81 SAG)细胞内外分布的影响

讨论了铜在淡水藻（Scenedesmus subspicatus86.81SAG)细胞壁和细胞内分布规律，以及乙二胺四乙酸（EDTA）和水体腐殖酸（FA）存在下对铜分布的影响，研究结果表明，EDTA和FA的存在显著降低了细胞表面铜的吸附量，但是不影响细胞内铜的浓度，对测定数据进行分析。可以认为溶液相铜与EDTA或FA形成的铜络合物是生物无效形态，不参与铜在藻细胞壁上特定位点或生物配体的竞争结合反应。     

颗粒物悬浮体系中聚合铝凝聚絮凝形态表征 (Ⅰ):Al-Feron法的应用研究

应用Ａｌ－Ｆｅｒｒｏｎ法于悬浮体系中聚合铝的形态分布表征，对其中的主要影响因素进行探讨，就不同碱化度聚合铝的形态分析进行实例研究．结果表明，混合方式对Ａｌ－Ｆｅｒｏｎ法的应用具有一定的影响作用．比色管混合测得Ａｌａ为２１．５４％，低于磁力搅拌方式结果（２４．５２％，２５．２２％，２５．０６％）．应用磁力搅拌方式可以获取较好的重复性与更多初期反应信息．颗粒物的存在对反应的影响主要取决于其浓度与粒度分布，成一定线性关系，可以从中加以扣除．在本实验范围内因其溶解所产生的影响可以忽略不计．对多个碱化度聚合铝的实例研究表明，Ａｌ－Ｆｅｒｏｎ法完全适用于颗粒物悬浮体系中的形态分布表征     

石墨炉原子吸收光谱法测定轻质油中痕量砷时样品前处理方法的探讨

研究了轻质油中痕量砷的几种样品处理方法。实验表明，石墨炉原子吸收光谱法测定时，用碘-甲苯和H2O2-HNO3相结合处理轻质油样品较为合适，萃取效率可达90％。并对影响萃取测定的其它因素作了初步探讨。     

土壤中钼的形态分析方法研究

本文对土壤中有效钼的浸取条件进行最佳化，并利用提高灰化温度达到消除浸取剂对石墨炉原子吸收测定钼的影响，方法用于国标样品和武汉市区土壤样品中钼的形态分析，获得满意的分析结果。     

沈阳张士污灌区土壤重金属元素形态分析

选取沈阳张士污灌区土攘样品,采用欧共体标准局的三步提取法研究土壤中5种重金属元素的形态分布.研究结果表明,在该污灌区土壤中,Cd和zn主要以B1(水溶态、可交换态与碳酸盐结合态)和B2(铁-锰氧化物结合态)为主,分别占总量的49.4%、26.4%和43.9%、44.3%.Cu、Pb主要以B2(铁-锰氧化物结合态)和B3(有机物与硫化物结合态)为主分别占总量的43.4%、66.6%和29.1%、25.3%.Cr以B3(有机物与硫化物结合态)和残渣态为主,分别占总量的40.4%和42.5%.元素总量和形态分析的结果表明该地区土壤污染为单一的镉污染土壤,且镉的可迁移性强,易被植物吸收.