Interaction between Cu and different types of surface-modified nanoscale zero-valent iron during their transport in porous media

This study investigated the interaction between Cu^2 + and nano zero-valent iron (NZVI) coated with three types of stabilizers (i.e., polyacrylic acid [PAA], Tween-20 and starch) by examining the Cu^2 + uptake, colloidal stability and mobility of surface-modified NZVI (SM-NZVI) in the presence of Cu^2 +. The uptake of Cu^2 + by SM-NZVI and the colloidal stability of the Cu-bearing SM-NZVI were examined in batch tests. The results showed that NZVI coated with different modifiers exhibited different affinities for Cu^2 +, which resulted in varying colloidal stability of different SM-NZVI in the presence of Cu^2 +. The presence of Cu^2 + exerted a slight influence on the aggregation and settling of NZVI modified with PAA or Tween-20. However, the presence of Cu^2 + caused significant aggregation and sedimentation of starch-modified NZVI, which is due to Cu^2 + complexation with the starch molecules coated on the surface of the particles. Column experiments were conducted to investigate the co-transport of Cu^2 + in association with SM-NZVI in water-saturated quartz sand. It was presumed that a physical straining mechanism accounted for the retention of Cu-bearing SM-NZVI in the porous media. Moreover, the enhanced aggregation of SM-NZVI in the presence of Cu^2 + may be contributing to this straining effect.     

Wastewater degradation by iron/copper nanoparticles and the microorganism growth rate

Nowadays, trends in wastewater treatment by zero-valent iron (ZVI) were turned to use bimetallic NZVI particles by planting another metal onto the ZVI surface to increase its reactivity. Nano size zero-valent iron/copper (NZVI/Cu⁰) bimetallic particles were synthesized in order to examine its toxicity effects on the wastewater microbial life, kinetics of phosphorus, ammonia stripping and the reduction of chemical oxygen demand (COD). Various concentrations of NZVI/Cu⁰ and operation conditions both aerobic and anaerobic were investigated and compared with pure NZVI experiment. The results showed that addition 10 mg/L of NZVI/Cu⁰ significantly increased the numbers of bacteria colonies under anaerobic condition, conversely it inhibited bacteria activity with the presence of oxygen. Furthermore, the impact of nanoparticles on ammonia stripping and phosphorus removal was also linked to the emitted iron ions electrons. It was found that dosing high concentration of bimetallic NZVI/Cu⁰ has a negative effect on ammonia stripping regardless of the aeration condition. In comparison to control, dosing only 10 mg/L NZVI/Cu⁰, the phosphorus removal increased sharply both under aerobic and anaerobic conditions, these outcomes were obtained as a result of complete dissolution of bimetallic nanoparticles which formed copper-iron oxides components that are attributed to increasing the phosphorus adsorption rate.     

铜绿假单胞菌对铜和铅的吸附

研究了铜绿假单胞菌(Pseudomonas aeruginosa)对Cu和Pb的吸附特性.结果表明,相同条件下,该菌株对Cu~(2+)的吸附率低于Pb~(2+).对于单一重金属体系,吸附率均随时间的延长先上升后平稳变化,2 h达到稳定.吸附率随投菌量的增加先迅速增加,之后趋于平稳.对于Cu~(2+),投菌量为1 g·L~(-1)时吸附率达到稳定,而Pb~(2+)的吸附效果达到平稳时的投菌量为0.5 g·L~(-1).单位质量菌体对Cu~(2+)、Pb~(2+)的吸附量随投菌量的增加而下降.pH为3时,菌体的吸附效果较差,当pH为5~8时,2种重金属的吸附效果较高.对于活菌,Pb~(2+)对菌体吸附Cu~(2+)有抑制作用,而Cu~(2+)对菌体吸附Pb~(2+)的影响无明显规律.对于失活菌,P.aeruginosa吸附Pb~(2+)和Cu~(2+)的效果均随共存重金属浓度的增大而降低,但Cu~(2+)对Pb~(2+)的影响比Pb~(2+)对Cu~(2+)的影响更显著.扫描电镜观察发现,吸附后的菌体较吸附前聚集性更好.总体而言,P.aeruginosa能对水体中共存的Cu~(2+)和Pb~(2+)有较好的吸附效果.     

天然有机物和电解质对水中 C60凝聚行为的影响

以富勒烯(C60)纳米颗粒稳定悬浮液为对象,采用动态光散射技术研究了天然有机物和电解质对其在水中凝聚行为的影响.结果表明,采用甲苯溶剂替换法制备的稳定悬浮液中C60浓度为20 mg·L-1左右,表面呈较高的电负性,粒径在120 nm左右,具有较强的稳定性.投加简单电解质可通过压缩双电层机制使其发生凝聚,并符合经典的胶体稳定性(DLVO)理论.Mg Cl2和Ca Cl2的临界凝聚浓度分别为9.6 mmol·L-1和6.7 mmol·L-1.腐殖酸(humic acid,HA)存在时,投加Na Cl和Mg Cl2可使C60颗粒间有效碰撞概率及凝聚反应速度降低,临界凝聚浓度提高;HA可通过增大C60颗粒间的空间位阻效应,抑制凝聚反应发生,提高其在水中的稳定性.但Ca2+可与HA间发生络合反应,并对C60纳米颗粒产生吸附架桥作用,导致凝聚速度大幅提高,强化凝聚反应发生.水中C60纳米颗粒的凝聚和分散行为将受到有机物性质和电解质种类等复杂因素的影响.     

Enhancing soil aggregation and acetamiprid adsorption by ecofriendly polysaccharides hydrogel based on Ca2+- amphiphilic sodium alginate

Soil aggregation plays an important role in agricultural production activities. However, the structure of soil aggregation is destroyed by the natural environment and unreasonable farming management, resulting in the loss of water, fertilizers and pesticides in soil. At present, hydrogels have been widely reported to promote the formation of soil aggregation. In this paper, amphiphilic calcium alginate (ASA/Ca²⁺) was applied to promote the formation of soil aggregation and enhance pesticide retention. Initially, an ASA was obtained through the one-pot Ugi condensation (a four-component green chemical reaction). Then, ASA/Ca²⁺ hydrogel is prepared by Ca²⁺ cross-linking. The formation of soil aggregation was determined through the Turbiscan Lab Expert stability analyzer, Confocal Laser Scanning Microscope (CLSM), and Transmission Electron Microscope (TEM). And the effect of soil aggregation on acetamiprid environmental behavior was investigated by adsorption kinetics, adsorption isotherms, and leaching. The results shown that the three-dimensional network structure of ASA/Ca²⁺ hydrogel can promote the formation of soil aggregation. Aggregate durability index (ADI) was 0.55 in the presence of ASA/Ca²⁺ hydrogel, indicating that amphiphilic hydrogel can enhance the stability of soil aggregation. The adsorbing capacity of acetamiprid was 1.58 times higher than pure soil, and the release of acetamiprid only about 20% in the presence of ASA/Ca²⁺ hydrogel. These results would be helpful for the formation of soil aggregation and pesticides adsorption on soil aggregation. Thus, ASA/Ca²⁺ hydrogel is likely to improve soil quality, simultaneously it can minimize the mobility of pesticides in the agricultural system.     

高选择性基因工程菌E.coli SE5000生物富集水体中的镍离子

利用基因工程菌E．coli SE5000对水体中的镍离子进行富集研究．菌体细胞对Ni^2 的富集速率很快,富集过程满足Langmuir等温线模型．经基因改造的基因工程菌不仅最大镍富集容量与原始宿主菌相比增加了4倍多,而且对pH值的变化呈现出更强的适应性．对离子强度及其它共存重金属离子的影响的实验结果表明：Na^ ,Ca^2 ,Cd^2 ,Pb^2 的影响较小,但Mg^2 ,Hg^2 ,Cr^3 和Cu^2 所引起的负面效应较大．金属螯合剂EDTA的存在对基因工程菌的富集行为影响很大．     

红纺锤水蚤(Acartia erythraea)对Cu2+和Ag+的吸收

通过对桡足类动物红纺锤水蚤(Acartia erythraea)分别在Cu2 、Ag 、Cu2 Ag 混合溶液中的暴露实验,测定了其对Cu2 、Ag 的吸收速率常数、排出速率常数,并对Cu2 和Ag 在动物体内的分布状况进行了分析.结果表明,在单金属暴露的条件下,红纺锤水蚤对Cu2 、Ag 的吸收速度分别为1.09×104L·g-1·d-1、3.31×104L·g-1·d-1,排出速率常数分别为0.096 d-1、0.1056 d-1.而在Cu2 Ag 的混合暴露体系中,红纺锤水蚤对Cu2 、Ag 的吸收速率分别下降到9.17×103 L·g-1·d-1、2.87×104L·g-1-d-1,Cu2 和Ag 的排出速度常数则分别降到0.084 d-1和0.1008 d-1.动态模型的模拟结果表明,Cu2 和Ag 存在一定程度的拮抗作用.与暴露在单金属溶液中的红纺锤水蚤相比较,在暴露于Cu2 、Ag 混合体系中动物体内的非极性部分所占的比重明显增加,说明其在食物链中对于上一营养级的生物有效性将明显增加.     

铜胁迫对不同基因型谷子幼苗基因组DNA多态性的影响

采用室内盆栽土培法,以4种基因型谷子(D2-8、安06、黄米、朝谷)为供试材料,研究了不同浓度Cu2+胁迫对谷子幼苗体内可溶性糖、脯氨酸、丙二醛(MDA)含量和基因组DNA多态性的影响.结果表明,经50~400 mg·kg-1Cu2+处理30 d后,4种谷子幼苗体内可溶性糖含量与对照相比呈现先上升后下降的趋势,在50 mg·kg-1时达到最大值.当浓度为200mg·kg-1以上时,4种谷子的可溶性糖含量的平均降幅为对照的32.44%~56.5%.脯氨酸则表现为低含量(≤50 mg·kg-1)的促进和高含量(≥100 mg·kg-1)的抑制效应,MDA含量均有增加且与对照差异显著(P<0.05).Cu2+胁迫下不同基因型谷子幼苗基因组DNA的RAPD图谱发生明显变化,表现为单条或多条RAPD谱带的增加和缺失或者荧光强度的改变,细胞中基因组模板DNA的稳定性下降,DNA多态性变化与Cu2+浓度之间存在剂量-效应关系.不同基因型谷子对Cu2+胁迫的生理和遗传损伤响应存在差异.利用RAPD技术获得的DNA多态性变化可作为检测Cu2+遗传毒性效应的生物标记物.     

沉积物产电信号原位在线监测水体铜污染研究

采用一种新型沉积物-微生物燃料电池(Sediment Microbial Fuel Cells,SMFCs)装置,探索产电信号原位在线监测湿地水体Cu~(2+)污染的可行性.采集水稻土装入烧杯并淹水以模拟湿地环境.将SMFCs装置的阳极不锈钢管插入水稻土,阴极淹没在上覆水中进行产电.采用数据采集卡在线记录电压.产电30 min后,分别向阴极附近的上覆水中加入5 mL Cu~(2+)浓度为50、100、200和400 mg·L~(-1)的CuSO_4溶液,对照加入5 mL去离子水,每个浓度处理设置两个平行.Cu~(2+)加入后,电压迅速上升并在30 s内达到峰值,之后随着Cu~(2+)扩散和被土壤吸附,电压回落并保持稳定.将加铜前30 min电压平均值作为基准电压,用加铜后的电压峰值减去基准电压得到电压增量.结果显示,电压增量与加入的Cu~(2+)浓度呈现显著正相关关系.为揭示相关机制,检测了CuSO_4溶液理化性质,并对加铜后SMFCs装置的阳极和阴极电荷传递电阻进行测定、对优势产电细菌梭菌属(Clostridium)和地杆菌科(Geobacteraceae)细菌16S rRNA基因进行定量.结果表明,Cu~(2+)促进阴极反应,是引起电压升高的主要原因.而底泥的吸附作用减弱了Cu~(2+)对产电细菌的抑制,保证了Cu~(2+)污染事件后产电信号恢复稳定.     

Effects of Cu2+ and humic acids on degradation and fate of TBBPA in pure culture of Pseudomonas sp. strain CDT

Soil contamination with tetrabromobisphenol A(TBBPA) has caused great concerns;however, the presence of heavy metals and soil organic matter on the biodegradation of TBBPA is still unclear. We isolated Pseudomonas sp. strain CDT, a TBBPA-degrading bacterium, from activated sludge and incubated it with ~(14)C-labeled TBBPA for 87 days in the absence and presence of Cu~(2+)and humic acids(HA). TBBPA was degraded to organic-solvent extractable(59.4% ± 2.2%) and non-extractable(25.1% ± 1.3%) metabolites,mineralized to CO_2(4.8% ± 0.8%), and assimilated into cells(10.6% ± 0.9%) at the end of incubation. When Cu~(2+)was present, the transformation of extractable metabolites into non-extractable metabolites and mineralization were inhibited, possibly due to the toxicity of Cu~(2+)to cells. HA significantly inhibited both dissipation and mineralization of TBBPA and altered the fate of TBBPA in the culture by formation of HA-bound residues that amounted to 22.1% ± 3.7% of the transformed TBBPA. The inhibition from HA was attributed to adsorption of TBBPA and formation of bound residues with HA via reaction of reactive metabolites with HA molecules, which decreased bioavailability of TBBPA and metabolites in the culture. When Cu~(2+)and HA were both present, Cu~(2+)significantly promoted the HA inhibition on TBBPA dissipation but not on metabolite degradation. The results provide insights into individual and interactive effects of Cu~(2+)and soil organic matter on the biotransformation of TBBPA and indicate that soil organic matter plays an essential role in determining the fate of organic pollutants in soil and mitigating heavy metal toxicity.     

PAA改性纳米铁强化还原降解水中亚甲基蓝

利用纳米零价铁去除水中各类污染物是近年来的研究热点,但纳米零价铁颗粒在水中的团聚会导致反应活性降低,研究通过在纳米铁颗粒制备过程中添加分散剂聚丙烯酸(PAA),提高其分散性,强化其在水中反应活性,合成改性纳米零价铁颗粒(PAA-Fe),并首次用于降解水中的亚甲基蓝.对其SEM、TEM、XRD和比表面积表征结果表明,与未改性原始纳米零价铁颗粒相比,PAA-Fe颗粒表面较光滑,团聚减少、颗粒粒径减小,比表面积增大.改性剂PAA添加浓度为0.1 g·L-1时,经过60 min降解反应,PAA改性纳米铁颗粒对亚甲基蓝的脱色率为98.84%,较未改性颗粒脱色率提高了27.32%.改性纳米铁颗粒对亚甲基蓝的脱色效果受初始溶液的p H值、初始溶液的浓度、PAA-Fe投加量和反应温度影响.PAA-Fe与亚甲基蓝的脱色反应符合假一级反应动力学规律.     

Mechanism of combination membrane and electro-winning process on treatment and remediation of Cu^2＋ polluted water body

Mechanism of treatment and remediation of synthetic Cu2+ polluted water body by membrane and electro-winning combination process was investigated. The influences of electrolysis voltage, pH, and electrolysis time on the metal recovery efficiencies were studied. Relationship between trans-membrane pressure drop ( P), additions ratio, initial Cu2+ concentration on operating efficiency, stability of membrane and the possibility of water reuse were also investigated. The morphology of membrane and electrodes were observed using scanning electron microscopy (SEM), the composition of surface deposits was ascertained using combined energy dispersive X-ray spectroscopy (EDX) and atomic absorption spectrophotometer. The results showed that using low pressure reverse osmosis (LPRO), Cu2+ concentration could increase from 20 to 100 mg/L or even higher in concentrated solutions and permeate water conductivity could be less than 20 μS/cm. The addition of sodium dodecy/sulfate sodium dodecyl sulfate improved Cu2+ removal efficiency, while EDTA had little side influence. In electro-reduction process, using plante electrode cell, Cu2+ concentration could be further reduced to 5 mg/L, and the average current efficiency ranged from 9% to 40%. Using 3D electrolysis treatment, Cu2+ concentration could be reduced to 0.5 mg/L with a current efficiency range 60%–70%.     

高分子重金属絮凝剂MAC除Cu2+、去浊性能

以壳聚糖、巯基乙酸等为原料合成了一种新型高分子重金属絮凝剂巯基乙酰壳聚糖(MAC),研究了其除Cu2 与去浊的机理,并对几个因素做了考察.实验结果表明:①MAC具有除铜与去浊的性能,当MAC与HPAM复配时,效果优于单独使用MAC,Cu2 去除率可达98%以上;②用MAC处理Cu2 和浊度共存的体系时,废水中的重金属离子和致浊物质可以起到相互促进去除的作用,出水中[Cu2 ]＜0.5mg·L-1,浊度＜3NTU;原水浊度越大,越有利于Cu2 的去除;③Cu2 的去除率随原水pH值的增大而提高,浊度的去除率则反之.     

铜离子的持续负荷对活性污泥生物硝化活性的影响

重金属对生物硝化的抑制是困扰很多污水处理厂脱氮效果的难题.本文采用间歇式活性污泥反应器(SBR),研究了模拟废水中不同浓度的Cu2+持续抑制及负荷停止后硝化效率、硝化细菌活性和Cu分布的变化.结果表明,硝化活性易受Cu2+的影响,抑制程度随着Cu2+浓度的增大和施加持续Cu2+负荷的运行周期的延长而提高,当活性污泥内、外吸附Cu的总量达(14.0±1.0)mg·g-1(以MLSS计)时,氨氮去除率降至26.5%±4.0%.Cu2+对氨氧化细菌(AOB)的抑制作用大于亚硝酸盐氧化细菌(NOB).在Cu2+负荷为10和20 mg·L-1的体系中,NOB可以全部或部分被驯化而适应含铜废水.恢复阶段,AOB和NOB的活性完全或部分恢复,恢复速率和程度随抑制期Cu2+投加浓度的增加而降低.反应体系内Cu主要分布在细胞内部和表面,且不易解析,硝化抑制率与溶解的Cu2+浓度呈负相关性.     

重金属铜在黑土和棕壤中解吸行为的比较

采用一次平衡法研究吸附态Cu²⁺在黑土和棕壤上的解吸行为并进行了比较.结果表明,与棕壤相比,黑土吸附态Cu²⁺解吸有更长的滞后阶段,黑土在Cu²⁺的吸附量低于729.00mg·kg^-1(Cu²⁺处理浓度小于40 mg·L^-1),棕壤在Cu²⁺的吸附量低于393.29 mg·kg^-1(Gu²⁺处理浓度小于20 mg·L^-1)时,土壤吸附态Cu²⁺几乎不发生解吸.2种土壤吸附态Cu²⁺的解吸率均较低,尤其是黑土.在试验所采用的Gu²⁺处理浓度范围内,黑土与棕壤吸附态Cu²⁺的最高解吸率分别为6.60%和13.56%.Freundlich方程为描述2种土壤Cu²⁺等温解吸过程的最佳方程.黑土和棕壤吸附态Cu²⁺的解吸速率均较快,在40min左右基本达到平衡.描述黑土和棕壤解吸动力学过程的最优模型为双常数速率方程,其次为Elovich方程.     

Fluorescence and metal-ion recognition properties of acetylacetone-based ligands

A new acetylacetone-based ligand (Ligand 1) bearing pyrene unit was synthesized and the fluorescence and metal-ion recognition properties were investigated in the presence of a different metal ion in acetonitrile solution. The fluorescence emission of Ligand 1 was strongly quenched by complexation with Cu²⁺ while no significant change was observed in the presence of other metal ions. The metal-ion selectivity changed from Cu²⁺ to Ni²⁺ when glycine moiety (–NH–CH₂–CO–) was introduced into Ligand 1 as spacer. This result implies that hydrogen-bonding induced by the glycine moiety affects the binding ability of ligands to metal ions, resulting in change of the metal-ion selectivity.     

ToxTell生物传感器在Cu2+、Zn2+冲击活性污泥系统分析中的应用

探讨了不同浓度Cu2+及Cu2+和Zn2+联合对活性污泥系统CODCr去除的影响,并采用ToxTell生物传感器,以活性污泥为指示微生物,分析了上述金属离子的毒性抑制作用.结果表明,Cu2+浓度为5mg·L-1时,其对活性污泥工艺CODCr去除存在一定的促进作用,随着Cu2+浓度的增加,其对CODCr的去除的抑制作用逐渐增强;Cu2+及Cu2+和Zn2+对活性污泥系统在抑制时间为1.5h时达到最大抑制状态,但随着曝气时间的延长,CODCr去除率呈逐渐上升趋势.ToxTell生物传感器对Cu2+和Zn2+的混合毒性具有良好的分析性能,其毒性分析结果与活性污泥工艺中CODCr的去除抑制率具有良好的一致性,初步证实该生物传感器能很好地用于活性污泥处理系统受Cu2+和Zn2+冲击的预警监测.     

Cu2+和Pb2+在BS-12两性修饰膨润土上的吸附及其交互作用

两性表面修饰可以同时提高黏土矿物对有机物、重金属的吸附性能,研究两性修饰土对多种重金属共存条件下的吸附及交互作用对于其应用具有实际意义.采用红外光谱(FTIR)对膨润土(CK)和150BS-12修饰土(150BS-12)吸附金属离子前后进行表征,通过批处理法研究不同比例BS-12修饰膨润土对Cu~(2+)和Pb~(2+)在单一及Cu-Pb复合体系中的平衡吸附特征和差异,并探讨金属离子在修饰土样上的交互作用机制.结果表明,供试土样在单一及复合体系中对Cu~(2+)和Pb~(2+)的吸附量均呈150BS-12 100BS-12 50BS-12 CK的顺序,吸附均符合Freundlich和Langmuir模型; BS-12修饰更有利于Cu~(2+)的吸附,但Pb~(2+)在BS-12修饰土样上的吸附量及选择性系数均大于Cu~(2+); Cu-Pb复合体系中,两种金属离子存在相互拮抗的作用,BS-12修饰在减弱Pb~(2+)对Cu~(2+)的拮抗作用的同时增强了Cu~(2+)对Pb~(2+)的拮抗作用,但Pb~(2+)对Cu~(2+)的拮抗作用仍大于Cu~(2+)对Pb~(2+)的拮抗作用;温度升高、p H升高和离子强度降低均能增加对Cu~(2+)和Pb~(2+)的吸附,但其对两种金属离子的影响程度不同,也导致对金属离子间的交互作用产生影响.     

壳聚糖/聚乙二醇/丙烯酸吸附剂对Cu2+、Co2+和Ni2+的吸附选择性和重复利用性

采用扫描电镜(SEM)和红外光谱(FT-IR)对辉光放电电解等离子体(GDEP)技术引发制备的壳聚糖/聚乙二醇/丙烯酸(CS/PEG/AA)聚合物吸附剂的形貌和结构进行了表征.研究了该吸附剂对Cu~(2+)、Co~(2+)和Ni~(2+)的吸附选择性、重复利用性和解吸动力学行为,同时结合X射线光电子能谱(XPS)探讨了可能的吸附机理.结果表明,CS、PEG和AA发生接枝共聚形成聚合物,其表面呈现疏松、多孔的三维网络结构;吸附最佳pH为4.8;在含有Cu~(2+)、Co~(2+)和Ni~(2+)的混合溶液中,CS/PEG/AA对Cu~(2+)有较好的吸附选择性;在EDTA-4Na洗脱液中CS/PEG/AA具有优异的再生和重复利用性,解吸动力学符合解吸准二级模型;Cu~(2+)在CS/PEG/AA上的吸附是由离子交换、配位螯合等共同作用的复杂的物理化学过程.     

One-pot synthesis of Fe/Cu-SSZ-13 catalyst and its highly efficient performance for the selective catalytic reduction of nitrogen oxide with ammonia

Series of Fe/Cu-SSZ-13 catalysts with different Fe loading content were synthesized by simple one-pot strategy. The obtained catalysts were subjected to selective catalytic reduction (SCR) of NO_x with NH₃ and were characterized by various techniques. The results show that Fe_0.63/Cu_1.50-SSZ-13 catalyst with proper Fe content exhibits excellent catalytic activity with widest operation temperature window from 160 to 580°C, excellent hydrothermal stability as well as good resistance to sulfur poisoning when compared with Cu-SSZ-13, signifying its great potential for practical applications. Further characterizations reveal that the synthesized Fe/Cu-SSZ-13 catalysts present typical chabazite (CHA) structure with good crystallinity, while isolated Cu²⁺ and monomeric Fe³⁺ are revealed as the predominant copper and iron species. At low temperatures, isolated Cu²⁺ species act as primary active sites for SCR reaction, while monomeric Fe³⁺ species provide sufficient active sites for sustain the SCR activity at high temperature. Moreover, Fe over doping would lead to the damage of zeolite structure, destruction of isolated Cu²⁺ site, as well as the formation of highly oxidizing Fe₂O₃, thus causing deterioration of catalytic performances.