乳状液膜法在湿法冶锌废水深度处理中的研究

提出深度处理湿法冶锌废水的二段液膜处理流程 ,并实验考察了分别回收锌、镉的适宜液膜条件 ,使得这 2种金属离子的达标排放与回收能够兼顾。     

湘江水体中重金属的化学形态及分布特征的研究

水体中重金属的生态效应和迁移转化规律与其化学形态密切相关。本文结合湘江重金属水容量与背景值的研究,较系统地研究了铜、铅、镉和锌的化学形态及其在全江段水中的分布特征。应用阳极溶出伏安法,得到湘江水中重金属总量、溶解态含量和悬浮态含量的分配与分布特征,还有溶解态所包含的金属的主要存在形态及与之共存的其它多种形态(包括悬浮态)共十种,该文对其形成、分配和相互转化进行了综合分析。     

Speciation of heavy metals in estuarine sediments in the northeast of Brazil

An analytical procedure involving a three-step sequential extraction was used to determine the chemical association of heavy metals (Zn, Cr, Mn and Fe) with the major phases (exchangable, reducible and oxidizable) in samples from a fishpond of estuarine sediments. The pond is located in the Capibaribe River estuary, within the boundaries of the city of Recife, in the State of Pernambuco in the northeast of Brazil. The total metal content was determined as well. All metals were extracted from the residual fraction at a percentage greater than 50%.     

蛭石吸附及解吸锌离子特性研究

用蛭石对锌离子的吸附解吸进行了实验研究,初步探讨了其对锌离子吸附解吸的机理。研究结果表明：蛭石对Zn^2＋具有较强的吸附能力,吸附在8h左右接近平衡。随着锌离子浓度的增加,蛭石的吸附量也在逐渐增加,当锌离子浓度达到400mg／L时,吸附量趋于平稳。在完成吸附实验的基础上,分别采用过滤和取上清液的方法解吸,实验证明静置平衡后,取出上清液50ml,再加入50ml解吸剂的方法解吸效果较好;解吸时间在0h到12h,蛭石的解吸量呈现递增的趋势,且达到1．070mg／g;在12h到48h内,解吸量基本没有增加,其中在24h时达到最大解吸量1．074mg／g。不同的解吸剂对蛭石解吸锌离子影响效果不同：蒸馏水不能使锌离子解吸;K^＋的影响作用相对于Na^＋更明显,随着两种阳离子浓度的增加,蛭石的解吸量逐渐增加。     

Variation of grain Cd and Zn concentrations of 110 hybrid rice cultivars grown in a low-Cd paddy soil

Enhanced Cd uptake and Zn depletion in rice grains and high potential for food Cd exposure by the high-yielding hybrid cultivars of China had been addressed. A field experiment was conducted in 2006 to determine the di erence in grain Cd and Zn between cultivars. Total 110 cultivars including super rice and common hybrid rice cultivars were grown on a single paddy soil (Entic Haplaquept) with a neutral reaction and low total Cd content. Grain Cd and Zn concentrations were determined with graphite atomic adsorption spectrophotometer (GFAAS) and flame atomic adsorption spectrophotometer (AAS) respectively.Wide variation of Cd content in grain was found in a range of 0.004–0.057 mg/kg, while the Zn content in a range of 10.25–30.06 mg/kg among the cultivars. Higher Cd but lower Zn concentration in grains of super rice cultivars was observed compared to the common hybrid ones. A highly significant positive linear correlation of grain Cd/Zn with grain Cd was found for super rice and common hybrid cultivars, meanwhile much higher slope for these hybrid cultivars than the reported non-hybrid cultivars was also observed. Using the limit value of the Chinese chemical guidelines for foods (MOHC and SSC, 2005), calculated potential risk of food Cd exposure with “Zn hungry” through diet intake was prominent with all the studied 110 hybrid rice cultivars, possessing high potential health problems for rice production in South China using the super rice cultivars. Breeding of genotypes of rice cultivars with low grain Cd and low Cd/Zn ratio is needed for rice production in acidic red soils where Cd bioavailability is prevalently high.     

Photocatalytic degradation of methyl orange over ITO/CdS/ZnO interface composite films

ITO/CdS/ZnO interface composite films were successfully prepared by subsequent electrodeposition of CdS and ZnO onto indium tin oxide (ITO) glass substrates. The obtained ITO/CdS/ZnO composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The photocatalytic activity of ITO/CdS/ZnO composite films were investigated using methyl orange (MO) as a model organic compound under UV light irradiation. The influence of operating parameters on MO degradation including initial concentration of MO, pH value of solution, and inorganic anion species over the composite films were examined. A blue shift of absorption threshold was observed for the ITO/CdS/ZnO film in comparison with ITO/ZnO film. ITO/CdS/ZnO composite films prepared under specific conditions showed a higher photocatalytic activity than that of ITO/ZnO films. It was also found that the photocatalytic degradation of MO on the composite filing followed pseudo-first order kinetics.     

火焰原子吸收法测定土壤中金属锌吸光度高的原因

通过实验发现,由于在消解过程中使用玻璃管移取氢氟酸,导致了玻璃中的锌进入了样品中,给样品的分析带来了干扰,从而导致了分析的失败.     

一株Zn抗性菌株的筛选鉴定及吸附条件优化

采用浓度梯度法从铅锌尾矿区与污水灌溉区土壤中筛选了一株Zn抗性放线菌,并通过形态与培养特征、生理生化特性、细胞壁组分与16SrRNA基因序列分析对该菌株进行了鉴定.同时,综合运用单因素试验与正交试验法对该菌株吸附Zn2+的条件进行了优化.结果表明,菌株CCNWHX72-14经鉴定为高加索链霉菌(Streptomyces ciscaucasicus),其对Zn2+的抗性达到845mg·L-1.锌胁迫生长曲线表明,该菌株在130mg·L-1Zn2+胁迫时生长良好,且最适培养时间为7d.各个单因素条件对该菌株吸附Zn2+的影响顺序为:接种量初始Zn2+浓度初始pH转速温度.该菌株吸附Zn2+的最佳条件为:初始Zn2+浓度为150mg·L-1,初始pH=5,接种量为1%,转速为60r·min-1,温度为28℃.菌株CCNWHX72-14在最佳条件下对Zn2+的吸附较具有良好的重复性与稳定性,最高吸附量可达51.05mg·g-1,该研究为进一步探讨链霉菌的Zn2+吸附机制及其在生物修复中的应用奠定了基础.     

Heavy metal （Pb,Zn） uptake and chemical changes in rhizosphere soils of four wetland plants with different radial oxygen loss

Lead and Zn uptake and chemical changes in rhizosphere soils of four emergent-rooted wetland plants; Aneilema bracteatum, Cyperus alternifolius, Ludwigia hyssopifolia and Veronica serpyllifolia were investigated by two experiments: (1) rhizobag filled with “clean” or metal-contaminated soil for analysis of Pb and Zn in plants and rhizosphere soils; and (2) applied deoxygenated solution for analyzing their rates of radial oxygen loss (ROL). The results showed that the wetland plants with di erent ROL rates had significant e ects on the mobility and chemical forms of Pb and Zn in rhizosphere under flooded conditions. These e ects were varied with di erent metal elements and metal concentrations in the soils. Lead mobility in rhizosphere of the four plants both in the “clean” and contaminated soils was decreased, while Zn mobility was increased in the rhizosphere of the “clean” soil, but decreased in the contaminated soil. Among the four plants, V. serpyllifolia, with the highest ROL, formed the highest degree of Fe plaque on the root surface, immobilized more Zn in Fe plaque, and has the highest e ects on the changes of Zn form (EXC-Zn) in rhizosphere under both “clean” and contaminated soil conditions. These results suggested that ROL of wetland plants could play an important role in Fe plaque formation and mobility and chemical changes of metals in rhizosphere soil under flood conditions.     

种植密度对镉锌污染土壤伴矿景天植物修复效率的影响

田间微区试验研究了不同种植密度对伴矿景天生长和地上部重金属吸收量的影响.结果表明,适度增大种植密度可促进伴矿景天的生长,显著提高其地上部生物量,但过分密植对植物地上部增产无显著贡献.种植密度由11万株/hm2上升到44万株/hm2时,伴矿景天地上部Cd、Zn吸取量显著上升,分别由0.208 kg.hm-2上升至0.631 kg.hm-2、13.2 kg.hm-2上升至58.7kg.hm-2;但种植密度从44万株/hm2增大到100万株/hm2时,植物地上部重金属吸取量并无显著提高.伴矿景天种植密度为44万株/hm2时,在Cd、Zn分别为(3.04±0.11)mg.kg-1和(1 299±96)mg.kg-1的污染土壤上种植1 a,对镉锌的修复效率分别达21.1%和4.60%,表明选择适宜的密度种植伴矿景天有利于增大植物地上部Cd、Zn吸取量,从而缩短修复时限.