高氯酸掺杂聚苯胺吸附Cr(Ⅵ)的机理研究

目的:研究聚苯胺对Cr(Ⅵ)的吸附机理。方法:采用扫描电镜、红外光谱、紫外-可见光谱、X射线衍射等表征手段比较高氯酸掺杂的聚苯胺对Cr(Ⅵ)吸附前后形貌和结构的变化,并通过动力学、吸附等温曲线等进行了线性拟合。结果:高氯酸掺杂的聚苯胺在吸附Cr(Ⅵ)前后形貌和结构都有所改变,其吸附过程能很好地符合准二级反应动力学方程和Freundlich等温吸附模型。结论:吸附过程中有氧化还原反应的发生,是物理吸附和化学吸附共同作用的结果。     

疏水型SiO_2气凝胶对Cr(Ⅵ)的吸附及动力学研究

以疏水型SiO2气凝胶为吸附剂,研究其对Cr(Ⅵ)的吸附性能。考查了pH、吸附时间、气凝胶用量对Cr(Ⅵ)吸附率的影响,探索了吸附Cr(Ⅵ)的动力学特性。实验结果表明,在pH=2、气凝胶的量m=0.4 g、反应时间t=75 min时,疏水型SiO2气凝胶对Cr(VI)的去除率较高;疏水型SiO2气凝胶对Cr(Ⅵ)吸附行为更符合准二级动力学模型;使用乙醇作为脱附剂,脱附效果较好。     

IRA-900树脂对废水中Cr(Ⅵ)的吸附性能

本文采用离子交换树脂处理含Cr(Ⅵ)废水并探讨其吸附能力,同时考察了树脂对Cr(Ⅵ)的吸附热力学和动力学。通过树脂筛选实验优选出IRA-900为较优吸附剂,并进一步考察了吸附时间、树脂用量、pH值、溶液初始浓度对吸附的影响;动态实验表明,树脂重复使用6次仍保持较高的吸附量和脱附率,说明该树脂可重复再生利用;热力学和动力学研究表明:Langmuir模型能更好地拟合树脂对Cr(Ⅵ)的吸附,IRA-900树脂对Cr(Ⅵ)的吸附过程更符合准二级动力学模型,说明该吸附过程主要以化学吸附为主。     

磁流体对工业废水中Cr（Ⅵ）的吸附

采用共沉淀法制备了粒径为10nm的Fe3O4磁性微粒,分散于水中生成饱和磁化强度35mT的水基磁流体,用此磁流体对模拟与实际废水中Cr（Ⅵ）进行了吸附研究。结果表明,吸附的最佳实验条件为pH=3,温度为45℃,吸附时间为0．5h。用Langmuir等温模型和假二级动力学模型探讨了磁流体对Cr（Ⅵ）的吸附机理,该过程为单离子层吸附。在最佳实验条件下,磁流体对实际制革废水中Cr（Ⅵ）的饱和吸附量达66．5mg／g,废水中残N／Cr（Ⅵ）浓度为0．2mg／L,低于工业废水排放的国家标准（0．5mg／L）。     

冰模板-微波法协同的用于吸附水中Cr(Ⅵ)的生物炭制备

该文采用新鲜含水的豆腐渣为原料,液氮冷冻后的冰为模板,利用微波加热快速制备功能性分级孔生物碳材料,用来吸附水中的重金属铬Cr(Ⅵ).文章探究了不同微波加热时间制备的生物炭的微观结构和化学组成差异,及其对Cr(Ⅵ)吸附的影响.该项研究为吸附水中的Cr(Ⅵ)提供了一种快速、绿色的方法,具有工业化应用的潜在价值.实验过程包括...     

TiO2-葡萄糖体系光催化还原Cr(Ⅵ)研究

研究了葡萄糖存在下TiO2光催化还原Cr(Ⅵ)过程中葡萄糖浓度、Cr(Ⅵ)初始浓度及不同反应条件对Cr(Ⅵ)光降解速率的影响．TiO2催化剂悬浮体系能有效地光催化还原溶液中Cr(Ⅵ)离子；葡萄糖的存在对TiO2的光催化还原Cr(Ⅵ)的反应具有明显的促进作用，符合一级反应动力学规律．     

不同活化剂制备的脐橙皮渣活性炭对Cr(Ⅵ)的吸附研究

采用H_3PO_4和Na OH为活化剂制备脐橙皮渣活性炭,从吸附时间、p H值、初始浓度、活性炭用量等因素研究两种活性炭对水中Cr(Ⅵ)的吸附性能.研究结果表明,碱法活化的活性炭吸附性能好于酸法活化的活性炭,两种活性炭对Cr(Ⅵ)的吸附可能都属于多分子层吸附,但碱法的活性位点更多.两种活性炭的最佳吸附条件分别为:酸法p H值:3.0,吸附时间:4 h,活性炭投入量:0.03 g,初始浓度:10 mg/l;碱法p H值:2.0,吸附时间:7 h,活性炭投入量:0.02 g,初始浓度:10 mg/l.     

酸枝锯末对Cr(VI)的吸附研究

实验研究了酸枝锯末对模拟含铬废水中的Cr（VI）的吸附性能,静态吸附结果表明,酸枝锯末对Cr（VI）具有较好的吸附效果．锯末对Cr（VI）的吸附率随着锯末用量的增加而增大;随着溶液初始pH的增大,吸附效果降低;随着吸附温度的上升,吸附效果升高．酸枝锯末对Cr（VI）的吸附符合拟二级吸附动力学模型（R2〉0．99）,吸附平衡前,颗粒内扩散为吸附速率的主要控制步骤;吸附过程可用Langmuir吸附等温线（砰〉0．99）来描述．吸附热力学研究表明,酸枝锯末对Cr（VI）的吸附为自发的吸热反应过程．     

农业废弃物花生壳对废水中Cr（Ⅵ）的静态吸附特性研究

采用废弃花生壳对Cr（Ⅵ）浓度为50mg/L的模拟水样进行了静态吸附实验研究。实验结果表明,对于Cr（Ⅵ）浓度为50mg/L的50mL模拟水样,在25℃下,用粒径为2-3mm花生壳吸附剂用量为1.0g、介质pH值为1.0、吸附时间为300min处理废水时,Cr（Ⅵ）的去除率可以达到99.55%。吸附后的水中Cr（Ⅵ）浓度为0.224mg/L,满足《污水综合排放标准》GB8978-1996的标准。随着体系温度的升高,花生壳对Cr（Ⅵ）的吸附量增加,同时对吸附等温线及其模型的拟合进行了实验说明,Freundlich模型能较好地反映吸附过程特征。     

铬的氢催化波及其铬的测定应用

铬(Ⅵ)和铬(Ⅲ)在NH_3H_2O·NH_4Cl—As(Ⅲ)溶液中能够产生氢的极谱催化波。在电极反应过程中,溶液中生成了铬合物Cr(H_2ASO_3)_n~(+3-n),这个铬合物的还原态吸附在滴汞电极上,具有催化活性。应用这种氢催化波可测定微量铬。在一定条件下,铬(Ⅵ)的浓度在2×10~(-8)～2×10(-7)M之间与其氢催化波峰高有很好的线性关系。本文仅讨论Cr(Ⅵ)的氢催化波。     

Competitive adsorption of Cd, Cu, Hg and Pb by agricultural soils of the Changjiang and Zhujiang deltas in China

Soils can often be contaminated simultaneously by more than one heavy metal. The sorption-desorption behavior of a metal in a soil will be affected by the presence of other metals. Therefore, selective retention and competitive adsorption of the soils to heavy metals can affect their availability and movement through the soils. In this study, the simultaneous competitive adsorption of four heavy metals (Cd, Cu, Hg, and Pb) on ten agricultural soils collected from the Changjiang and Zhujiang deltas, China was assessed. The results showed that the competition affected the behavior of heavy metal cations in such a way that the soils adsorbed less Cd and Hg, and more Pb and Cu with increasing total metal concentrations, regardless of the molar concen- tration applied. As the applied concentrations increased, Pb and Cu adsorption increased, while Cd and Hg adsorption decreased. The adsorption sequence most found was Pb>Cu>Hg>Cd. The maximum adsorption capacity for the heavy metal cations was calculated, and affected markedly by soil properties. The results suggest that Hg and Cd have higher mobility associated to the lower adsorption and that Pb and Cu present the opposite behavior. Significant correlations were found between the maximum adsorption capacity of the metals and pH value and exchangeable acid, suggesting that soil pH and exchangeable acid were key factors controlling the solubility and mobility of the metals in the agricultural soils.     

柚子皮对水中六价铬的吸附性能研究

采用柚子皮制备生物吸附剂用于去除水中的Cr(VI),考察了p H值、柚子皮投加量、柚子皮粒径、溶液离子强度、反应温度等因素对吸附效果的影响。结果表明,当溶液中Cr(VI)离子初始浓度15mg/L、p H 1.5、反应温度25℃、柚子皮投加量1.0g/100 m L、吸附时间7 h时,Cr(VI)离子去除率可达90%以上。柚子皮对Cr(VI)离子的吸附过程可以用Langmuir和Freundlich吸附等温模型来描述,吸附等温线线性相关性均较显著,吸附过程符合准二级动力学方程。柚子皮对水中Cr(VI)离子吸附性能较好,且运行成本低,可推广应用于水中重金属离子的治理。     

木麻黄叶状枝粉末对Cr（Ⅵ）离子的吸附性能

以木麻黄叶状枝粉末作为生物吸附剂,研究其对重金属离子Cr（Ⅵ）的吸附性能和吸附规律,并探讨了溶液酸度、振荡时间、溶液初始浓度、吸附剂用量等因素的影响.结果表明,在吸附剂用量为0.3g、pH值为1、Cr（Ⅵ）初始浓度小于100mg/L、吸附时间为90min的条件下,相应的吸附容量和吸附率可达3.98mg/g和99.9%,残余的Cr（Ⅵ）浓度小于0.5mg/L,达国家工业废水排放标准GB18918-2002;正交实验结果表明,影响木麻黄吸附剂对Cr（Ⅵ）吸附效果的主次因素顺序为pH值〉吸附振荡时间〉吸附剂用量〉吸附液浓度.     

啤酒酵母对Zn~(2+)、Mn~(2+)和Cu~(2+)的吸附探究

文中利用啤酒酵母去除模拟废水中Zn2+、Mn2、Cu2+,通过对预处理试剂、吸附温度、吸附液pH值与浸泡时间等因素进行正交分析,确定了影响吸附的主要因素是酸度和预处理试剂.研究pH值、离子初始浓度、吸附时间、离子强度等条件对吸附率的影响,结果表明,用NaOH浸泡后2h,在pH=5~6时吸附效果最好.用吸附等温线Langmuir(exe)、Freundlich和Temkin方程拟合,相关性都比较好.用不同的吸附动力学方程描述啤酒酵母吸附金属离子的最优模型为Elovich方程.     

重金属Cu在土壤-根系界面迁移特征研究——以淮南矿区为例

以木本植物女贞为例,根据木本植物吸附土壤重金属特点,布设采样点,利用Sufer软件,进行Kiging插值分析,模拟重金属Cu在土壤-根系界面系统的横向迁移特征;通过多模型统计回归趋势分析,探寻重金属Cu在土壤-根系系统中不同剖面水平方向上的迁移机制。土壤-根系系统重金属空间分布特征研究对于土壤的污染风险评价以及植物修复土壤效应研究具有重要意义。     

功能化介孔材料对重金属离子吸附的研究进展

介绍了功能化介孔材料的制备方法：共合成方法和后嫁接方法。分析比较这两种方法的优缺点,并总结了功能化介孔材料在各种重金属离子吸附处理方面的应用,以期为更好发挥功能化介孔材料在重金属方面的应用提供参考。     

改性花生壳对废水中Cr（Ⅵ）的静态吸附特性研究

利用酸性甲醛溶液将废弃花生壳改性,研究了改性花生壳对Cr（Ⅵ）浓度为50mg/L的模拟水样的静态吸附实验效果。实验结果表明,对于Cr（Ⅵ）浓度为50mg/L的50mL模拟水样,当温度为25℃用粒径为2-3mm改性花生壳吸附剂用量为1.0g、介质pH值为1.0、吸附时间为300min处理废水时,Cr（Ⅵ）的去除率可以达到99.71%。吸附后的水中Cr（Ⅵ）浓度为0.144mg/L,满足《污水综合排放标准》GB8978-1996的要求。改性花生壳比普通花生壳对废水中Cr（Ⅵ）的吸附能力更强。     

Characterization of suspended solids and particle-bound heavy metals in a first flush of highway runoff

To investigate the dynamic characteristics of total suspended solids （TSS） and their particle-bound heavy metals in a first flush, the runoff sampling together with its flow rate measuring was conducted for three rainfall events at outfalls of highway in Shanghai from June to September 2007. Field samples were analyzed to determine the concentrations of TSS and particle-bound heavy metals, such as Zn, Pb, and Cu. Results show that the wash offbehavior of TSS under varying runoffrate condition can be explained by different antecedent dry weather period （ADWP）. Contribution of fine fraction （〈45 μm） to TSS was generally higher than that of coarse fraction （〉45 μm）. When the runoff flow increased obviously, a significant contribution of the coarse fraction was observed for a certain rainfall events with long antecedent dry weather condition. The changes of total metals concentration and particle-bound metal concentrations were strongly dependent on the TSS variation. TSS was generally well correlated with most particulate-bound heavy metals. Of the heavy metals, the concentration of Zn was found considerably high and that of Pb was significantly low at North Zhongshan 2 Road, in Shanghai, China, but they are still within the range reported in the literature. Fluctuation of heavy metal contents in the coarse fraction during a first flush period was more significant compared with that in the fine fraction. The results will assist in the development of effective control strategies to minimize heavy metals and solids in highway runoff.     

Genotypic and environmental variation in cadmium, chromium, arsenic, nickel, and lead concentrations in rice grains

Genotypic and environmental variation in Cd, Cr, As, Ni and Pb concentrations of grains, and the relationships between these heavy metals and Fe, Zn were investigated using 9 rice genotypes grown in 6 locations for two successive years. Significant genotypic variation was detected in the five heavy metal concentrations in grains, indicating the possibility to reduce the concentration of these heavy metals in grains through breeding approach. The environmental effect varied with metal, with Pb and Ni having greater variation than the other three metals. There was significant genotype-environment （location） interaction of the concentrations of all five heavy metals in grains, suggesting the importance of cultivar choice in producing rice with low heavy metal concentrations in grains for a given location. Correlation analysis showed that Cd and As, Cr and Ni, and As and Pb concentrations in rice grains were closely associated, and that Ni concentration in grains was negatively correlated with Zn concentration.     

Fe2O3 as indicator of heavy metal enrichment in Zhujiang(Pearl River) estuary sediments

A part of the heavy metals in estuary and coastal zone occurs naturally in the environment; the other part is due to human activity; so the directly measured concentration of heavy metal does not automatically indicate anthropogenic enrichment. Fe2O3 was used in this study as conservative tracer to distinguish natural components from anthropogenic components of heavy metal sediment concentration in the Zhujiang estuary. Compared with clay and Al2O3, Fe2O3 is more suitable as reference element. The final results showed that two zones in the Zhujiang estuary were seriously contaminated by heavy metals. One nearby the Humen mouth; the other around the west coast of the estuary. The horizontal distribution of heavy metals indicates that Zn, Ni and Cu have wider contaminating areas than TiO2, V and Cr in the estuary.