洗相废水中银回收技术研究

采用电解法和离子交换法回收洗相废水中的银.结果表明,电解法对高浓度含银洗相废水的银回收处理是一种行之有效的方法.对于中低浓度洗相废水中的银的回收,采用4%硫酸再生IRA-68离子交换树脂,树脂的交换能力可以增加4倍,再生时由于已交换的银被直接固定在树脂上,结果使得再生剂处置和银回收过程更加简单方便.IRA-68离子交换树脂回收中低浓度洗相废水中银的技术具有银回收效率更高、离子交换运行时间更长和操作更为简便等优点,使得传统的离子交换技术得到极大的改进和提高.     

等度洗脱快速分离SO4^2-、PO4^3-的新方法和

多聚磷酸盐在分离柱上保留能力强，不易洗脱，因此采用离子色谱分析测定多聚磷酸盐时大多采用梯度淋洗的方法，实现多聚磷酸盐、硫酸盐的分离。具体方法为采用美国戴安ICS-1000型离子色谱仪，METROSEP A Supp 5 100型分离柱，36mmol LiOH＋2％乙腈的淋洗液等度淋洗；进样20μL，流速0．7mL／min，8min内实现SO4^2-：PO4^3-和P2O7^4-的完全分离，保留时间分别为3．9，4．9和6．4min；检出限分别为4、11和17ng／L；加标回收率分别为96．88％，96．41％和98．48％。     

Review of the application of quantum dots in the heavy-metal detection

Heavy-metal contamination is a major concern, as excessive heavy metals produce environmental pollution, and the cumulative effects of heavy metals in vivo pose a major threat to human health. There is an urgent need for a rapid, sensitive, and efficient method for detecting heavy metals. Quantum dots (QDs) are in the category of semiconductor nanocrystals whose radii are less than or close to the exciton Bohr radius. QDs possess a potential in the biological and medical fields to function as a new type of fluorescent marker, because of their unique and tunable photophysical properties, which include broad excitation spectrum, narrow emission spectrum, tunable emission wavelengths, and negligible photobleaching. In recent years, QDs made significant progress in quantitative analysis by providing a new approach for determination of chemical content analysis. The aim of this study was to review the research progress of QD detection of heavy metals in water and consider the challenges and future outlook for QD-based sensors for heavy-metal ions.     

Trace elements in particulate matter of ambient air at petroleum filling stations

Size segregated suspended particulate matter (PM_2.5 and PM_10-2.5) in air at four major petroleum-filling stations in Ile-Ife, Nigeria, were monitored using double staged “Gent” stacked samplers to assess variations in mass loads and elemental concentrations of 25 elements. Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr, Cs, Ta, W, and Pb were determined in both fractions by external ion beam proton-induced X-ray emission technique. Enrichment factors and pollution indices were calculated and results revealed that most elements were anthropogenic in both fractions with concentrations exceeding the World Health Organization guideline standards.     

Sensitivity of veliger larvae of Mytilus edulis and mussel of various sizes to chlorination

The blue mussel Mytilus edulis is one of the dominant fouling organisms in cooling water systems. In this work, how veliger larvae and different size groups of the mussels responded against chlorine dosage was examined. Veliger larvae mortality was studied at different residual chlorine concentrations (0.05–0.5 mg L^?1), and it was found that a chlorine dose of 0.5 mg L^?1 is 4 times as effective as 0.05 mg L^?1 and twice as effective as 0.1 mg L^?1. Mortality of 100% for three size groups (1.4, 14, and 25 mm) and relative physiological activities of two size groups (14 and 25 mm) were observed. The exposure duration for 100% mortality of mussels decreased with the increasing residual chlorine concentration (0.1–4.0 mg L^?1). Mussel size was also found to be an important factor, considering that the continuation times for mussel mortality were 28 h for the 1.4 mm and 410 h for the 25 mm size groups. All size groups showed progressive reduction in physiological activities, such as oxygen consumption, foot activity, and byssus thread production with increasing chlorine dose (0.05–1.0 mg L^?1); the two data-sets were strongly correlated with each other. The results of this study should be of significance for optimizing the chlorine content, and minimize the environmental threat to industries where mussels are the dominant fouling organisms.     

Treatment,residual chlorine and season as factors affecting variability of trihalomethanes in small drinking water systems

Seasonal variability in source water can lead to challenges for drinking water providers related to operational optimization and process control in treatment facilities. The objective of this study is to investigate seasonal variability of water quality in municipal small water systems (<3000 residents) supplied by surface waters. Residual chlorine and trihalomethanes (THM) were measured over seven years (2003–2009). Comparisons are made within each system over time, as well as between systems according to the type of their treatment technologies. THM concentrations are generally higher in the summer and autumn. The seasonal variability was generally more pronounced in systems using chlorination plus additional treatment. Chloroform, total THM (TTHM) and residual chlorine concentrations were generally lower in systems using chlorination plus additional treatment. Conversely, brominated THM concentrations were higher in systems using additional treatment. Residual chlorine was highest in the winter and lowest in the spring and summer. Seasonal variations were most pronounced for residual chlorine in systems with additional treatment. There was generally poor correlation between THM concentrations and concentrations of residual chlorine. Further study with these data will be beneficial in finding determinants and indicators for both quantity and variability of disinfection byproducts and other water quality parameters.     

Nexus between polymer support and metal oxide nanoparticles in hybrid nanosorbent materials (HNMs) for sorption/desorption of target ligands

Metal oxide nanoparticles like hydrated ferric oxide (HFO) or hydrated zirconium oxide (HZrO) are excellent sorbents for environmentally significant ligands like phosphate, arsenic, or fluoride, present at trace concentrations. Since the sorption capacity is surface dependent for HFO and HZrO, nanoscale sizes offer significant enhancement in performance. However, due to their miniscule sizes, low attrition resistance, and poor durability they are unable to be used in typical plug-flow column setups. Meanwhile ion exchange resins, which have no specific affinity toward anionic ligands, are durable and chemically stable. By impregnating metal oxide nanoparticles inside a polymer support, with or without functional groups, a hybrid nanosorbent material (HNM) can be prepared. A HNM is durable, mechanically strong, and chemically stable. The functional groups of the polymeric support will affect the overall removal efficiency of the ligands exerted by the Donnan Membrane Effect. For example, the removal of arsenic by HFO or the removal of fluoride by HZrO is enhanced by using anion exchange resins. The HNM can be precisely tuned to remove one type of contaminant over another type. Also, the physical morphology of the support material, spherical bead versus ion exchange fiber, has a significant effect on kinetics of sorption and desorption. HNMs also possess dual sorption sites and are capable of removing multiple contaminants, namely, arsenate and perchlorate, concurrently.     

太湖北部流域水化学特征及其控制因素

为了解太湖北部流域主要河网区水质受该流域地质状况、岩石和土壤的化学风化作用以及人类活动的影响等方面,对太湖北部流域河网区主要河道水体中的主要离子进行了采样研究。结果表明：太湖北部流域水体中的TDS平均值为355．74mg·L-1,变化范围为276．08--681．54mg·L-1,其中ca2＋和HCO3-是占绝对优势的离子,分别占阳离子和阴离子总量的46．2％和48．9％;其次是Na＋和SO42-,分别占阳离子和阴离子总量的35．9％和27．5％。进而判断出该流域水化学类型是以碳酸盐岩石和蒸发岩来源为主的HCO3-Ca2＋-Na＋型。再从离子的自然起源和人类活动角度分别对水化学类型的控制因素进行分析,一方面利用吉布斯分布模式投点作图得出结论：其离子自然起源的优势机制是岩石的风化作用,而蒸发一结晶和大气降水的输入作用十分微弱,这与该流域的水文、地理、地质背景相一致;另一方面通过SPSS软件的相关关系分析得出结论：NO3-、SO42-、心、ca2＋和Mg2＋的相关性较强,与cl‘也呈正相关,说明水体中这些主要离子都具有共同的来源,其中NO3-的较高含量（平均值为14．74mg·L-1）反映了该流域受人类影响较大。尤其是NO3-与sO42-的相关性达到0．83,再次说明氮污染对该流域水体的酸化和水质变化有较大影响。     

上海沿海防护林空气负离子水平测定

空气负离子被誉为“空气维生素”,是衡量空气质量的重要指标。为了探讨城市防护林改善人居环境的效应,选择上海南汇地区的沿海防护林作为研究对象,对空气负离子水平进行了分析测定。结果表明,不同土地利用方式、林分内不同空间空气负离子分布呈现显著差异;负离子水平随林分树种不同而变化。不同土地利用方式下负离子浓度表现为：林地〉小区〉...     

改性柚子皮吸附剂对模拟废水中Pb^2＋的吸附性能

以废柚子皮为原料,经ZnCl2浸泡一加热的化学改性手段制备改性柚子皮生物吸附剂,并通过模拟试验研究该吸附剂对废水中Pb^2＋的去除。考察了模拟废水的pH、吸附时间、吸附剂用量和Pb^2＋初始浓度、温度等因素对柚子皮吸附剂去除Pb^2＋的影响,并研究柚子皮吸附剂对Pb^2＋的吸附动力学及吸附特征。结果表明,模拟废水的pH、吸附时间、吸附剂用量和Pb^2＋初始浓度、温度等因素对柚子皮吸附剂吸附废水中Pb^2＋均有显著影响。适宜的吸附条件为pH5．3-6．5,吸附时间1．5h,吸附剂用量10g·L^-1,Pb^2＋初始质量浓度100mg·L^-1,温度30℃。在该条件下,废水中Pb^2＋去除率在90％以上。柚子皮吸附剂对废水中Pb^2＋的吸附符合动力学二级反应方程,等温吸附规律可用Langmuir、Freundlich和Temkin模型进行较好的描述。