Effects of Na+ on Cu/SAPO-34 for ammonia selective catalytic reduction

Copper-exchanged chabazite (Cu/CHA) catalysts have been found to be affected by alkali metal and alkaline earth ions. However, the effects of Na⁺ ions on Cu/SAPO-34 for ammonia selective catalytic reduction (NH₃-SCR) are still unclear. In order to investigate the mechanism, five samples with various Na contents were synthesized and characterized. It was observed that the introduced Na⁺ ion-exchanges with H⁺ and Cu^2 + of Cu/SAPO-34. The exchange of H⁺ is easier than that of isolated Cu^2 +. The exchanged Cu^2 + ions aggregate and form “CuAl₂O₄-like” species. The NH₃-SCR activity of Cu/SAPO-34 decreases with increasing Na content, and the loss of isolated Cu^2 + and acid sites is responsible for the activity loss.     

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.     

Mulberry-silkworm food chain--a templet to assess heavy metal mobility in terrestrial ecosystems

Assessment of the food chain mobility of heavy metals inthe natural ecosystem receives more attention nowadays. Inthe present study, mulberry-silkworm food chain has beenfocused as a templet to assess the biomobility of heavymetals in soil-higher plant-insect hierarchy. Both in thecase of Cd and Cu treatments, higher mobility wasobserved in the level-1 (soil–root) followed by level-3(leaf–larva), level-4 (larvae–faecal) and level-2(root–leaf). Consequently, roots accumulated more amountsof Cd and Cu, with a limited transport to the leaves.Among the two metals (Cd and Cu) tested, in the plant,the transfer potential of Cd exceeds that of Cu. Whereasin the case of leaf–larval transfer, Cu precedes overCd. Accumulation of Cd and Cu in all the levels (1–4)tested showed a concentration dependent increase, except inthe level 4 (larva–faecal) of Cd treatment where adeclining trend was noticed.     

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。     

金属铁还原降解2,4-二硝基甲苯的实验研究

研究了金属铁对2,4-二硝基甲苯(2,4-DNT)的还原降解情况.实验结果表明,2,4-DNT的还原降解与溶液初始pH值、初始浓度和溶解氧等因素有关.氯离子能消除金属铁的钝化现象.金属铁表面附载的铜对2,4-DNT的还原降解具有催化作用.     

植物多酚物质原位钝化污染土壤重金属的研究Ⅱ.对土壤Cu环境行为和生物活性的影响动态

通过室内好气培养和生物盆栽试验研究了缩合类植物多酚L和Y以及 8 羟基喹啉在污染红壤和潮土中的降解动态及其对土壤Cu环境行为的影响 .结果表明植物多酚在两周内降解相对较快 ,而 8 羟基喹啉则难以降解 .与空白相比 ,Cu污染土壤中施用植物多酚后土壤水溶性Cu显著下降 ,钝化Cu的效果次序为 :8 羟基喹啉 >多酚Y >多酚L .随着植物多酚的降解 ,土壤Cu被释出 ,其水溶性Cu浓度与残留在土壤中多酚浓度 (以DOC浓度表示 )呈负相关关系 ,尤其在潮土上更为明显 ,而pH与水溶性Cu没有相关性 .试验还发现 ,钝化剂施用后 ,小麦体内的Cu含量降低 ,因此 ,植物多酚是钝化重金属污染土壤的良好选择     

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。     

长江中下游海相三叠系膏盐层与铜(金)、铁矿床

长江中下游海相三叠系膏盖层中含有很大比例的大、中型铜（金）、铁、多金属矿床。膏盐层不仅是铜（金）、铁矿床的主要赋矿层位之一，而且是部分成矿金属的矿源层；膏盐层还为燕山期岩浆提供部分钠质、钾质及挥发组分，影响岩浆演化的方向，改变了含矿流体的性质；另外，从岩体和矿床中金属硫化物中流同位素重硫成分的增高，说明在成者、成矿过程中，膏盐层是硫的供应者之一。因此膏盐层与铜（金）、铁、多金属矿床之间存在着特殊的成因联系。     

铜、锌和锰抑制月形藻生长的毒性效应

运用评价化学品毒性藻类测试的标准实验方法，得到铜、锌和锰对月形藻生长的最小无显著差异浓度（LNOEC）分别为31.8μg/L、16.4μg/L和2.7mg/L，抑制月形藻生长的96h半效应浓度（96h-EC50)分别为199.5μg/L、38.0μg/L和12.6mg/L。实验结果表明无论从LNOEC还是从96h-EC50考虑，都证明抑制月形藻生长的毒性由大到小的顺序是锌＞铜＞锰。此结果对铜抑制藻类生长的毒性远远大于锌的毒性这一人们普遍认同的观点构成挑战。月形藻细胞壁表面可能含有较少的硫代基团但包含较多与锌有很强结合能力的官能团可能是导致月形藻对铜的敏感性弱而对锌敏感性强的主要原因。     

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