萃取法分离回收不锈钢酸洗污泥硫酸浸出液中的重金属

采用非皂化P204和皂化P204萃取剂对不锈钢酸洗污泥的硫酸浸出液进行萃取。在浸出液pH为0.80、非皂化P204体积分数为25%、萃取剂与浸出液体积比为1∶2、萃取时间为5 min的条件下,Fe~(3+)萃取率达99.64%,Cr~(3+)和Ni~(2+)萃取率为3.98%和6.99%,一次萃余液pH为0.64。采用皂化P204对除Fe~(3+)后的一次萃余液进行萃取,在P204体积分数为25%、萃取剂与浸出液体积比为1∶2、萃取剂皂化率为60%、一次萃余液pH为1.50、萃取时间为5 min的条件下,Ni~(2+)萃取率为93.12%,Cr~(3+)萃取率为20.69%,二次萃余液pH为2.63。     

阴角邻面火灾作用下L型钢管混凝土柱耐火极限研究

运用有限元软件ABAQUS计算L形带肋钢管混凝土柱阴角相邻两面受火全过程下的耐火极限,分析了阴角邻面受火方式下构件内部温度场和应力场的变化规律,在此基础上分析荷载比、宽厚比、计算长度、加劲肋纵向间距、荷载偏心率、荷载角等参数对耐火极限的影响规律。数据表明:荷载比、计算长度对构件耐火极限影响较大,随着荷载比和计算长度的增大,耐火极限基本呈线性下降;加劲肋间距对构件耐火性能影响较小;由于L形柱的特殊形式,偏心荷载对耐火极限的影响规律较复杂,荷载作用点偏向低温区可以提高耐火极限。     

水体重金属污染生物监测的研究进展

综述了重金属的毒性效应和水体重金属污染的现状,介绍了利用水生藻类、浮游动物群落和底栖动物监测水体重金属污染的研究进展及发展趋势。     

粉煤灰基层状金属氧化物对水中活性红X-3B的吸附

以粉煤灰(FA)为原料,采用共沉淀法制备了层状双金属氢氧化物(LDH)和层状金属氧化物(LMO,也称LDO),并采用XRD和BET技术进行了表征。比较了FA、LDH、LMO对活性红X-3B染料(X-3B)的吸附效果;考察了LMO吸附X-3B的影响因素,并探讨了吸附机理。XRD表征结果表明,LMO在吸附X-3B后重新恢复LDH层状结构。BET表征结果表明,LMO的比表面积大于LDH。吸附实验结果表明,3种吸附剂对X-3B吸附效果的优劣顺序为:LMOLDHFA;在初始X-3B质量浓度为50 mg/L、LMO投加量为2.0 g/L、吸附温度为25℃、吸附pH为7、吸附时间为30 min的条件下,X-3B去除率可达98.1%;LMO对X-3B的吸附符合Langmuir等温吸附方程,饱和吸附量为129.53 mg/g,且吸附过程可用准二级动力学方程描述。     

金属冶炼进口物料的固体废物鉴别方法

建立了金属冶炼进口物料的固体废物鉴别方法,并利用该方法对海关查扣的3种金属冶炼进口物料进行了固体废物鉴别。鉴别结果显示:物料1、2和3的自然属性分别为砷含量超标铜精矿、锰阳极泥、回转窑氧化锌,产生来源分别为有害物质超标的产品、污染控制设施产生的物质、有意识加工的目标产物;物料1和2属于我国禁止进口的固体废物,物料3不属于固体废物。本文建立的固体废物鉴别方法可行,可为金属冶炼进口物料的固体废物鉴别和监管提供参考。     

重金属Cr(VI)、Pb及Cu胁迫对双齿围沙蚕体腔细胞的DNA损伤

为探讨重金属Cr(VI)、Pb以及Cu对沙蚕体腔细胞DNA的毒性效应,以双齿围沙蚕为受试动物,重金属按不同剂量水平,Cr(VI):10、100和200 mg·L~(-1),Pb:5、50和100 mg·L~(-1),Cu:1、10和20 mg·L~(-1),分别胁迫沙蚕24 h,以不加任何重金属离子的海水为对照,采用单细胞凝胶电泳技术,检测其体腔细胞DNA损伤程度。结果表明,与空白对照组相比,3种重金属离子的各浓度组都能引起沙蚕体腔细胞DNA损伤,且3种重金属胁迫浓度与细胞DNA损伤程度之间存在显著的剂量-效应关系。双齿围沙蚕可以作为单细胞凝胶电泳的实验材料用于重金属所致环境污染的生物监测指示生物。     

肠道微生物对土壤中铜、锌、锰生物可给性的影响

为了更全面、准确地评价土壤中金属元素对人体的健康风险,研究土壤中金属元素在结肠阶段的生物可给性具有重要意义。通过采集我国一些地区的6种土壤,利用in vitro方法(PBET和SHIME联用)研究土壤中Cu、Zn、Mn在胃、小肠、结肠阶段的生物可给性。研究显示,土壤中Cu、Zn、Mn在胃阶段的生物可给性分别为23.8%~63.0%、21.2%~64.4%、11.7%~35.6%;从胃阶段到小肠阶段,土壤中Cu的生物可给性提高了0.4%~14.4%,而土壤中Zn在小肠阶段的生物可给性降低了6.7%~38.7%。结肠阶段,土壤中Cu、Zn、Mn的生物可给性分别为2.4%~12.9%、5.7%~18.7%、6.2%~18.9%,与小肠阶段相比,分别降低了21.7%~56.9%、0.4%~36.8%、4.5%~19.1%。结果表明,在肠道微生物存在的情况下,土壤中Cu、Zn、Mn在结肠阶段有较低的人体健康风险。     

重金属Cr(Ⅵ)、Pb及Cu胁迫对双齿围沙蚕体腔细胞的DNA损伤

为探讨重金属Cr(Ⅵ)、Pb以及Cu对沙蚕体腔细胞DNA的毒性效应,以双齿围沙蚕为受试动物,重金属按不同剂量水平,Cr(Ⅵ):10、100和200 mg· L-1,Pb:5、50和100 mg·L-1,Cu:1、10和20 mg· L-1,分别胁迫沙蚕24 h,以不加任何重金属离子的海水为对照,采用单细胞凝胶电泳技术,检测其体腔细胞DNA损伤程度.结果表明,与空白对照组相比,3种重金属离子的各浓度组都能引起沙蚕体腔细胞DNA损伤,且3种重金属胁迫浓度与细胞DNA损伤程度之间存在显著的剂量-效应关系.双齿围沙蚕可以作为单细胞凝胶电泳的实验材料用于重金属所致环境污染的生物监测指示生物.     

Trace metals distribution and their dependence on some physico-chemical parameters in creek sediment

The concentrations of the trace metals Mn, Zn, Cr, V, Co, Ni, Ba, Pb, Cu, Cd, As and Hg, their spatial distribution, and their correlation as a function of physico-chemical parameters were investigated for grab sediment samples collected from different locations across the Thane Creek, Mumbai, India. Hydride generation atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, and differential pulse anodic stripping voltammetry were adopted for chemical analyses. Various geochemical indices were evaluated. The studied metal/metalloids were compared with sediment quality guideline values. Besides, the role of different physico-chemical parameters of the sediments such as pH, CaCO₃, cation exchange capacity, total carbon, and of the relative composition in respect to very coarse, coarse and medium sand, fine sand and very fine sand, silt and clay fraction were also critically investigated. Positive one-to-one correlations between fine sand and very fine sand, silt and clay, and total carbon with sediment metal concentrations have been noticed. Multiple regression analysis reveals strong positive correlations between sediment metal concentrations and total carbon content only.     

Nanocatalyzed biodiesel synthesis from the oily contents of Marine brown alga Dictyota dichotoma

This research article demonstrates biodiesel synthesis through the methanolysis of the oily contents (4.02 ± 0.27% w/w on dried basis) of Dictyota dichotoma collected from the coast of Hawksbay, Pakistan. The metal oxides (CaO, MgO, ZnO, and TiO₂) used as nanocatalysts were refluxed (5% K₂SO₄), calcinated (850 °C) and characterized by Atomic Force Microscopy (AFM) which produced 93.2% w/w FAME (biodiesel) at relatively mild condition (5% catalyst, 65 °C, 3 h, 18:1 molar ratio) using CaO. Whereas, MgO, ZnO, and TiO₂ produced 92.4%, 72.5%, and 31.8% w/w FAME, respectively at elevated condition (225 °C). Thus, CaO was considered to be the best catalyst among the others. This tri-phase reaction require continuous fast mixing and the yield depends on the reaction parameters like catalyst amount, temperature, reaction time and molar ratio (methanol: oil). The reusability of these heterogeneous catalysts simplified the purification step, reduced the waste generation and make the final product technically and economically viable.