芦苇对重金属Pb和Mn吸收和富集的研究

叙述了芦苇对重金属离子Pb2+,Mn2+的生物吸附特征以及其对水体中重金属离子的去除率受不同重金属初始浓度的影响和芦苇根、茎、叶对重金属离子的富集情况,指出,芦苇对Mn2+的吸附在35 min内达到平衡,对Pb2+的吸附在50 min内达到平衡,吸附动力学结果符合伪二级动力学方程,决定系数分别为0.984 6和0.971 3;Freundlich等温线可较好地拟合芦苇吸附Mn2+及Pb2+的过程,Mn2+及Pb2+的吸附量分别达到8.281 8 mg/g和6.025 3 mg/g。芦苇各器官对Mn2+富集强于对Pb2+的富集能力。不同器官对同种重金属离子的富集量差异显著,茎叶是富集Mn2+的主要器官,根是富集Pb2+的主要器官。     

自组装构筑MgO改性生物质炭及其磷吸附性能研究

为了提升MgO改性生物质炭的磷吸附能力,文章以花生壳为载体,利用碱式碳酸镁前驱体自组装-热解技术制备了结构有序的花瓣状MgO改性生物质炭吸附剂(FMgO-BC)。采用SEM,EDS,XRD,IR和TG表征了制备的FMgO-BC的物相结构与表面形貌,并研究了水解温度和Mg;浓度对FMgO-BC吸附性能的影响。研究结果表明,当水解温度为80℃,Mg²⁺浓度为0.6 mg/L时,FMgO-BC的吸附性能最优。文章还探究了FMgO-BC在不同pH值和加入量条件下的等温吸附模型和吸附动力学,研究结果表明,FMgO-BC的磷吸附动力学符合准二级动力学方程,等温吸附模型符合Langmuir等温吸附方程,理论最大吸附量为2221.89 mg/g,优于目前报道的MgO改性生物质炭的磷吸附性能。     

改性粉煤灰对生活污水磷的吸附研究

采用单因素的试验方法研究各因素对改性粉煤灰吸附性能的影响.对改性粉煤灰处理含磷生活污水进行了正交实验研究,结果表明各因素对磷酸根的去除率的影响顺序为:水灰比>初始磷浓度>吸附时间>pH值,极差R分剐为7.3%、6.6%、3.9%和3.3%.在pH=6.5、水灰比V/M=16.7、吸附时间T=40min、初始磷浓度Co=8.0mg/L时粉煤灰具有最佳的除磷效果.粉煤灰吸附磷的行为符合H等温方程,方程为:Y=0.1092X相关系数:R=-0.99970     

铀在放射性废物处置场周边土壤中的吸附行为及机理研究

放射性核元素在土壤介质中的吸附特征是放射性废物处置场地选址及安全评价中最重要的考虑因素之一。为探讨核素铀在放射性废物处置场预选场址周边土壤介质中的吸附行为与机理,实验以深圳市蛇山顶(SSD)及阳江市大尖山(YJ)表层土壤为研究对象,采用批式实验法研究不同铀初始质量浓度及离子强度对其吸附核素铀行为的影响,并通过吸附动力学模型及吸附等温线模型对实验数据进行拟合,分析吸附机理。结果表明:当铀初始质量浓度增大时,SSD及YJ土壤对U(VI)的平衡吸附量也增大,但去除率则分别从97.07%、91.56%下降至88.55%、87.93%;离子强度对SSD土壤吸附U(VI)的影响并不显著,表明U(VI)在SSD土壤上的吸附可能以内层络合反应为主;准二级动力学方程及Langmuir吸附等温模型能够很好地拟合吸附动力学及平衡吸附实验结果,相关系数R2均在0.99以上。实验获取的这些参数为核素铀在土壤介质上的吸附模型的建立提供了重要依据,且为推测核素铀在环境中的迁移行为提供了研究基础。     

活性污泥微波热解残余半焦吸附亚甲基蓝

采用活性污泥微波热解所得的残余半焦作为吸附剂,研究了其对亚甲基蓝的吸附效果.试验结果表明,当热解时间为15 min、热解原料中半焦添加量为10％的条件下,污泥半焦的吸附容量达到80.01 mg/g.动力学分析表明,亚甲基蓝在污泥半焦表面的吸附符合准二级动力学模型,吸附速率常数为6.83×10-4 g/(mg·min).分别用Langmuir和Freundlich等温方程对数据进行拟合,等温吸附过程能较好地用Freundlich吸附等温线描述,这表明磷在半焦表面的吸附受多种机制影响.     

地热水温下α型活性氧化铝对砷的吸附动力学研究

4个地热水温下α型活性氧化铝（α-AA）吸附砷的动力学研究表明当pH=4.6时,α-AA对As（Ⅲ）/As（Ⅴ）的吸附都是初始吸附速率快,达到吸附平衡需时短的过程;随温度升高,α-AA吸附As（Ⅲ）/As（Ⅴ）的4h平衡吸附容量qe,exp都无明显变化;α-AA吸附As（Ⅲ）/As（Ⅴ）全过程符合拟二级动力学方程,0.25~1min内,α-AA对As（Ⅲ）/As（Ⅴ）的吸附均符合Elovich方程,1~5min内,α-AA对As（Ⅲ）的吸附属于颗粒内部扩散过程。     

改性锯屑对钙镁离子的吸附特性研究

研究用改性锯屑处理废水中钙锾离子的新方法,通过静态实验研究改性锯屑的吸附容量;通过动态试验研究了进水速度和浓度等因素对Ca2+、Mg2+吸附过程的影响以及探讨改性锯屑的吸附再生.实验表明,低流速和高浓度废水溶液对改性锯屑提高Ca2+、Mg2+吸附容量有利;用NaCl溶液可时吸附饱和的改性锯屑进行再生.     

生物质灰渣对甲基橙废水的去除性能及机制

为将资源化生物质灰渣用于甲基橙(MO)废水的处理,在明确MO初始浓度、pH值、反应时间和温度影响的基础上,探讨MO去除的潜在机制和效果提升途径。结果表明,MO的去除随MO初始浓度的增加而增加,并在80 mg/L时趋于平衡。pH值为2时有利于吸附的进行,且MO去除在12 h内较为迅速,24 h后趋于平衡。Langmuir模型可较好地模拟生物质灰渣对MO的吸附过程,表明该吸附过程属于单分子层吸附,且对MO的理论最大吸附量为25.2 mg/g。此外,灰渣吸附MO能较好地被二级动力学拟合,说明化学吸附是MO去除的主控机制。FT-IR光谱进一步表明吸附机制主要由静电、表面络合物或沉淀等共同作用。此外,添加H₂O₂(最终质量浓度4%)可使MO的去除率提高67.2%,是提升灰渣对MO去除性能的有效途径。     

二价铁系离子对混合菌种光合产氢的影响

针对不同浓度的Fe2+、Co2'和Ni2+对混合菌种的光合产氢与生长的影响进行实验研究.结果表明适当浓度的二价铁系离子对产氢及生长具有一定促进作用.Fe2+、Co2+和Ni2+最佳产氢浓度分别为9.00、0.45和0.10wnol/L,而对产氢的影响作用大小顺序为:Fe2+>Ni2+>Co2+.二价铁系离子在适当浓度范围内可提高生长速率,其中Co2+对生长的促进作用最大.由于pH值影响二价铁系离子对产氢酶活性的作用,针对Fe2+浓度在不同初始pH值时对混合菌种光合产氢的影响进行实验研究.结果表明当pH=7.0时,Fe2+ 浓度的变化对产氢的影响最显著.而在本试验范围内,随着pH值偏离7.0,Fe2+浓度的变化对产氢的影响逐渐减小.     

曝气-Fenton处理焚烧厂渗滤液MBR-NF浓缩液研究

采用曝气-Fenton法对焚烧厂渗滤液经MBR-NF处理后产生的浓缩液进行预处理.探讨FeSO4·7H2O投加量、H2O2投加量、pH等因素对COD去除率及UV254、E4/E6的影响,并在此基础上对该反应降解COD过程的动力学方程进行分析与讨论.结果表明,最佳反应条件为:初始pH值为3,FeSO4· 7H2O投加量为0.025mol/L,H2O2投加量为0.125mol/L.曝气-Fenton法对焚烧厂渗滤液膜浓缩液的COD降解过程符合二级反应动力学方程.     

改性蛋壳材料对重金属离子的去除机理研究

以废弃蛋壳为主要原料,通过微波法和铁改性法分别合成吸附材料ME和FE,采用扫描电镜、X射线衍射以及比表面积分析仪进行表征,并考察材料对废水中Cu~(2+)、Cd~(2+)、Pb~(2+)的吸附性能及其影响因子(反应时间、吸附剂投加量、重金属离子初始质量浓度以及溶液pH)。结果表明:ME对Cu~(2+)、Cd~(2+)的吸附效果较好,当废水中Cu~(2+)、Cd~(2+)的初始质量浓度为50 mg·L~(-1)、ME的投加量为0.6 g·L~(-1)、pH=4时,反应20 min后,ME对Cu~(2+)、Cd~(2+)的去除率均高达100%,其饱和吸附量分别为179.2、183.6 mg·g~(-1);FE对Pb~(2+)的吸附效果较好,当废水中Pb~(2+)的初始质量浓度为50 mg·L~(-1)、pH=6时,FE对Pb~(2+)的饱和吸附量可达87.23 mg·g~(-1),Langmuir吸附等温方程可较好地描述该吸附过程。     

Novel porous carbons synthesized from polymeric precursors for hydrogen storage

In this work, porous carbons were prepared from polymeric ion-exchangeable resin by a chemical activation method in order to obtain novel hydrogen storage materials, and the adsorption characteristics of the porous carbons were investigated. The textural properties were studied by BET and D–R methods with adsorption isotherms. The hydrogen storage behaviors of the porous carbons at 298 K and 100 bar were studied using a PCT apparatus. In the observed post-activation result, the hydrogen storage capacity was markedly improved. However, it was also found that the total amount of adsorption was not proportional to the specific surface area of the adsorbates. This indicates that hydrogen storage could be a function not only of specific surface area or total pore volume but also of microporevolume fraction or the average pore size of adsorbents.     

Immobilization of Heavy Metals and Phenol on Altered Bituminous Coals

Abstract

This article evaluates adsorption ability of the altered bituminous coals to remove heavy metals and/or phenol from aqueous solutions. As for heavy metals, copper (II), cadmium (II) and lead (II) cations were used. In addition to phenol, cyclohexanol and 2-cyclohexen-1-ol were also examined. Adsorption experiments were conducted in the batch mode at room temperature and at pH 3 and 5. To characterize the texture of coal samples, adsorption isotherms of nitrogen at ?196°C, enthalpies of the immersion in water, and pH values in aqueous dispersions were measured. Coal hydrogen aromaticities were evaluated from the infrared spectrometric examinations (DRIFTS). Based on the investigations performed, cation exchange was confirmed as the principal mechanism to immobilize heavy metallic ions on coals. However, apart from carboxylic groups, other functionalities (hydroxyl groups) were found to be involved in the adsorption process. During adsorption of phenol, π-π interactions between π-electrons of phenol and aromatic rings of coal proved to play the important role; however, no distinct correlation between adsorption capacities for phenol and hydrogen aromaticities of the coal was found. Probable involvement of oxygenated surface groups in the immobilization of phenol on coal was deduced. As a result, for waste water treatment, oxidative altered bituminous coal can be recommended as a suitable precursor, with the largest immobilization capacities both for metallic ions and phenol, as found in the studied samples.     

Influence of Pb2+ ions in the H2 oxidation on Pt catalyzed hydrogen diffusion anodes in sulfuric acid: presence of oscillatory phenomena

The influence of Pb²⁺ ions in sulfuric acid medium on the behavior of a platinum catalyzed hydrogen diffusion electrode (HDE) in a filter press reactor has been studied. A voltammetric study of the H₂ oxidation reaction on a polyoriented platinum electrode and a platinum rotating disk electrode (RDE) in presence of lead ions in solution has also been carried out. Potential oscillations were found in galvanostatic experiments of H₂ oxidation using a HDE catalyzed with platinum when Pb²⁺ ions are present in solution. This oscillatory phenomenon was also observed when hydrogen oxidation was carried out in presence of Pb²⁺ ions using a platinum RDE. The oscillatory behavior observed has been attributed to an adsorption–oxidation–desorption process of lead on the platinum surface. Due to the low solubility of Pb²⁺ in sulfuric acid, at high values of coverage, lead is oxidised to insoluble lead sulfate that blocks the Pt surface. The coupling of the dissolution of lead sulfate and the Pb electrochemical adsorption–oxidation processes cause the oscillatory phenomenon.     

Fundamentals of electrochemistry (Ⅳ) --Electrode kinetics

电极过程动力学对电化学过程起着支配作用,研究成果广泛用于化学工业,能源领域,材料科学和环境保护等领域.电极过程主要由扩散传质,传荷过程以及表面吸附/脱附步骤构成.电活性物质从溶液主体到电极表面的传质过程包括对流,扩散和电迁移三种基本形式.电流-电势关系是表征电极反应动力学的基本途径,并在特定的电极条件下,可以推导得出Tafel半对数极化曲线公式和Butler-Volmer电极动力学公式.广义的表面转化过程包含了前置的表面转化步骤和后置的表面转化步骤.此外,利用流体力学计算能够反映电极表面流体流动对旋转圆盘电极过程的传质影响.通过对上述基本概念的总结与归纳,能够加深对电化学核心内容的把握,有利于研究开发新型应用电化学技术.     

Effect of Nanobubble Evolution on Hydrate Process: A Review

As a huge reserve for potential energy, natural gas hydrates(NGHs) are attracting increasingly extra attentions, and a series of researches on gas recovery from NGHs sediments have been carried out. But the slow formation and dissociation kinetics of NGHs is a major bottleneck in the applications of NGHs technology. Previous studies have shown that nanobubbles, which formed from melt hydrates, have significant promotion effects on dissociation and reformation dynamics of gas hydrates. Nanobubbles can persist for a long time in liquids, disaccording with the standpoint of classical thermodynamic theories, thus they can participate in the hydrate process. Based on different types of hydrate systems(gas + water, gas +water +inhibitors/promoters, gas + water + hydrophilic/hydrophobic surface), the effects of nanobubble evolution on nucleation, dissociation, reformation process and "memory effect" of gas hydrates are discussed in this paper. Researches on the nanobubbles in hydrate process are also summarized and prospected in this study.     

多孔介质淤沙对混凝土坝地震响应的影响分析

针对淤沙对混凝土坝地震响应的影响问题,基于液固两相介质的Biot固结理论,推导了饱和多孔液固两相 介质的压力波动方程,并以某混凝土坝为例,分析了不同淤沙孔隙率、渗透系数及淤沙层厚度对混凝土坝面地震 响应的影响。实例应用结果表明,淤沙能降低坝面动水压力、减小混凝土坝对地震的响应,且一定的淤沙对坝体 抗震有益。     

Removal of Cu(II) from aqueous solution using the rice husk carbons prepared by the physical activation process

The adsorption of Cu(II) from aqueous solution by carbons prepared from rice husk through pyrolysis and steam activation was studied. The rice husk carbon was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and its pore structure was also examined. After comparing different characteristics of the carbons prepared under different conditions and their adsorption abilities of Cu(II), the optimum temperature for pyrolysis and steam activation was chosen as 700 and 750 °C, respectively, using 3% (V/V) steam as the best activation gas. It was found that the Cu(II) adsorption on the rice husk derived carbons was pH and temperature dependent with an optimum pH value of 5.0, and an equilibrium time of 24 h. The adsorption kinetics and isotherms of Cu(II) by the rice husk derived carbons were also investigated under four different temperatures, and good correlation coefficients were obtained for the pseudo-second-order kinetic models, and the Langmuir isotherm model fitted very well with the experimental data. The mean free energy E (kJ mol⁻¹) obtained in the Dubinin-Radushkevitch (D-R) adsorption isortherm equation indicated a chemical ion-exchange mechanism. Several thermodynamic parameters were also caculated to predict the nature of adsorption process.     

Uptake of Metal Ions on Humic Acids

The kinetics, the sorption capacities, pH and temperature dependence of sorption of humic acids (HAs) of Turkish brown coals with respect to Zn(II), Cu(II), Ni(II), Co(II) and Pb(II) ions were investigated, and the roles of the carboxylic and phenolic groups in the adsorption of metals ion on HAs were searched in this work. These metal ions are able to form complex compounds with carboxylic and phenolic groups of HAs. Adsorption equilibrium was achieved in between 50 and 60 min for all studied cations. HAs extracted from different brown coals have been characterized by chemical and physical methods. The chemical properties of HAs showed differences depending on the source from which they were obtained. The sorption of metals on the surface of HAs depends strongly on the pH, and sorption decreases with decreasing pH. Maximum removal of metal ions was demonstrated at pH values of 4.1–5.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The Δ G ⁰ became negative as the temperature increased, and so the equilibrium constant decreased slightly. The investigation proved that the HAs are suitable materials for the studied heavy metal ion removal from aqueous solution and could be considered as potential material for purification of effluent polluted with toxic metal ions.