活性炭吸附去除重金属研究进展

介绍了国内外学者应用活性炭吸附去除包括:Cr(Ⅵ),Cu2 ,Zn2 ,Cd2 ,Pb2 ,Mn2 ,Hg2 以及混合重金属离子在内的各种废水的处理效果与影响因素,并对相应的吸附机理进行了讨论,以促进活性炭吸附去除重金属离子的进展。     

Uptake of metal ions by chemically treated human hair

The uptake capacity of chemically treated human hair waste for the various metal ions can be arranged in the following decreasing order: Hg²⁺ (Hg⁺), Ag⁺, Pb²⁺, Cd²⁺, Cu²⁺ (Cu⁺), Cr⁶⁺, Ni²⁺, Cr³⁺.The uptake capacity is significantly affected by the presence of other metal ions. Anionic effect was found to be more pronounced for a mixed ions system than for a single ion system.     

无机固形物对重金属的吸附去除特性研究

采用石英砂和高岭土为吸附剂,以典型重金属Cu,Zn,As,Cr为吸附质分别进行了单吸附剂单吸附质等温吸附实验,研究了无机颗粒物对重金属离子的吸附去除特性以及无机颗粒物对金属离子吸附水相化学条件影响因素,得出了一些有参考价值的结论。     

The effect of pH and hardness metal ions on the competitive interaction between trace metal ions and inorganic and organic complexing agents found in natural waters

The effect of pH and hardness metal ions on the interactions between trace metals and both inorganic and organic complexing agents has been studied under conditions simulating natural aquatic conditions, by employing anodic stripping voltammetric titration techniques. The complexation of Bi(III), Cd(II), Cu(II), Pb(II), and Tl(I) with the hydroxo- and carbonato-ligands found in a carbonate medium has been observed to generally increase with increasing pH. Both labile and nonlabile interactions have been observed. Nonlabile interactions are predominant at low pH and labile interactions generally increase with increasing pH. Neither calcium nor magnesium affects these interactions. The complexation of humic acids with trace metals in a carbonate medium was found to be more intense than metal ion-inorganic complexation. Both labile and nonlabile complexation was found; however, no generalizations can be made concerning the type and extent of complexation because of the individual nature of the interactions of each trace metal. Calcium was found to be more effective than magnesium in inhibiting trace metal-organic complexation. The effect of calcium is to inhibit labile complexation and is most pronounced with the cadmium-humic acid system.     

混凝土中重金属离子溶出试验方法的评述

混凝土中重金属离子长期溶出性能的研究应建立在可靠的溶出试验方法基础上.主要介绍了国内外用于固体废弃物中重金属离子的溶出试验方法,并指出了传统溶出试验方法在混凝土中应用的局限性.最后对混凝土中重金属离子溶出的试验方法进行了探讨.     

Modeling the sorption kinetics of divalent metal ions to hematite

The sorption kinetics of the divalent metals Zn, Co, Ni, and Cd to hematite were studied in single sorbate systems with high sorbate/sorbent ratios (from 1.67 to 3.33mol sorbate/mol sorption sites) in 10mM Na-piperazine N,N'-bis 2-ethane sulfonic acid (Na-PIPES) solution at pH 6.8. The experimental data showed a rapid initial sorption (half-time about 1min) followed by slower sorption that continued for 1-5 days. The sequence of fast to slow sorption kinetics was modeled by slow inner-sphere (IS) complexation in equilibrium with outer-sphere (OS) complexes. Although the OS reaction was fast and considered to be in equilibrium, the extent of OS complexation changed over time due to increased surface potential from the IS complexes. For example, the model showed that the dimensionless OS complexation function, K(os), decreased from 0.014 initially to 0.0016 at steady state due to sorption of 4x10(-5)M Zn(II) to 2gL(-1) hematite. Sorption rate constants, k(ads), for the various divalent metals ranged from 6.1 to 82.5M(-1)s(-1). Desorption rate constants, k(des), ranged from 5.2x10(-7) to 6.7x10(-5)s(-1). This study suggests that the conversion from OS to IS complex was the rate-determining step for the sorption of divalent metals on crystalline adsorbents.     

基于非平衡热力学理论的黏土多组分重金属吸附模型

黏土垫层土颗粒的吸附特性是控制溶质运移的重要关键因素,进而影响对防渗屏障长期服役性能的准确评估。在传统单组分吸附模型的基础上,基于非平衡热力学和Ziegler最大耗散率原理,通过构建弥散型自由能函数和弥散型耗散率函数,采用连续介质力学方法建立了非理想状态体系下适用于多组分重金属离子的非平衡态吸附模型。所建模型预测的多组分重金属离子吸附行为与已有试验结果吻合度较好,对比分析结果表明:所建非平衡态吸附模型能够正确揭示多组分重金属离子在黏土中的吸附动力学机制。     

黄土对锰离子的吸附特性及机理研究

重金属污染事件频发引起了很多学者的关注,锰是一种重金属痕量元素,人体通过食物链摄入过量的锰会产生中毒效应。研究了Mn(II)的浓度、反应温度、土水比、pH值等因素对Mn(II)在黄土上吸附特性的影响。黄土对Mn(II)的吸附容量可达7.84 mg/g,等温吸附模型Langmuir、Freundlich和D-R模型都能很好地解释Mn(II)在黄土上的吸附性能。热动力学分析表明Mn(II)在黄土上的吸附是一个自发的过程,升高温度可促进吸附作用的进行。增大土水比可提高Mn(II)的去除效率,但单位黄土上Mn(II)的吸附量有个最优值。Mn(II)的初始浓度越大单位黄土的最大吸附量越小,达到最大吸附量所需的土水比越高。溶液的酸碱度是影响Mn(II)去除效果的一个重要因素,pH>10.7时Mn(II)几乎完全被去除。通过X光衍射图谱和红外光谱分析,探讨了黄土与Mn(II)的结合机理,黄土中的黏土矿物、有机质成分对重金属Mn(II)的吸附起重要作用。     

环境中金属离子与有机污染物复合污染研究进展

金属离子与有机污染物可通过多种方式同时存在于环境中,形成复合污染。由于金属离子与有机污染物的相互作用,二者的物理化学性质、迁移转化规律以及生态毒性效应都发生了变化,给污染物的水处理过程以及污染物的生态毒性评估带来极大的挑战。综述了环境中金属-有机物复合污染的来源、金属离子与有机污染物之间的相互作用、共存对二者去除效率的影响以及复合污染的生态毒性研究,以期为复合污染的防治与处理工艺研究提供参考。     

陶瓷纤维在金属增强作用中的要求及类型

介绍了金属基复合材料的发展 ,阐述了铝纤维、碳化硅纤维及碳纤维在金属基复合材料中的应用 ,指出金属基复合材料具有耐高温性、耐磨损、抗老化等特性。     

Observations on the use of iron(II) complexing agents to fractionate the total filterable iron in natural water samples

Analysis of filtered natural water samples using Fe(II) complexing agents (bathophenanthrolinedisulphonic acid, 2,2′-dipyridyl, ferrozine, TPTZ) and acetic acid-sodium acetate buffer (pH 4.6) showed that the absorbance of the iron(II) complex increased with time both in the presence and the absence of a reducing agent (ascorbic acid, hydroxylammonium chloride). Exposure of the samples to 0.1 M HCl (pH 1.3) for 1 h prior to the addition of the complexing reagents resulted in a stable iron concentration which was designated the acid-extractable fraction of the total filterable iron. The results have implications for the complexometric determination of iron fractions other than total iron after acid digestion.     

新生态水合氧化铁去除水中磷酸根的效能研究

以新生态水合氧化铁(FHIO,由高铁酸钾和氯化亚铁配制)为混凝剂,考察了对水中磷酸根的处理效能,以及有机物浓度、pH、温度、浊度等参数对其去除磷酸根的影响。通过对原水pH和浊度变化的分析,发现FHIO的水解过程不同于普通铁盐,可形成细小、比表面积大、吸附能力强的铁氧体。在投加氯化铁进行混凝时,随着投量(6、7、8mg/L)的增加,对磷酸根的去除率分别达到了54%、59%、70%。而在相同的总铁投量下,FHIO对磷酸根的去除率分别提高了11%、13%、9%。水中有机物浓度的增加,对FHIO的除磷效果有一定的影响,这是因为有机物在一定程度上抑制了Fe(Ⅱ)的氧化,间接地影响了FHIO的生成,从而降低了除磷效果。在较低温度、pH和浊度时,FHIO对磷酸根的去除效果明显优于单独铁盐的,这是由于FHIO的无定形状态和细小的颗粒度决定其受这些因素的影响较小。     

Combined effect of carbon dosage and initial adsorbate concentration on the adsorption isotherm of heavy metals on activated carbon

The adsorption of dissolved chromium and lead ions by powdered activated carbons significantly depends on the pH, initial adsorbate concentration and carbon dosage. Freundlich and Langmuir equations were unable to describe adequately the observed isotherms under the combined influence of both the carbon dosage and initial adsorbate concentration. These equations were modified and the resulting equations were found to correlate well with the experimental equilibrium data. The modified Langmuir equation gave an overall mean ratio of calculated to experimental adsorptive capacity of 1.001 compared with 1.046 given by the modified Freundlich equation for a total of 135 sets of equilibrium data obtained at different carbon dosages and initial adsorbate concentrations.     

优先流作用下的胶体-重金属共迁移试验研究

土壤中的重金属污染物大部分源自外界的工、农业排放,地表土层是重金属迁移至地下的必经途径。由于干缩和动植物活动,地表土中存在大孔隙,形成污染物运移的优势通道,在一些情况下,这些通道是重金属穿过包气带向下迁移的唯一途径。针对胶体对重金属具有较大吸附能力且在优先流条件下具有移动性,从而可能加快重金属污染物迁移这一问题,通过等温吸附试验确定了上海表层褐黄色粉质黏土与土壤胶体对重金属镉、铅的吸附特征,制备具有可重复性优先流特征的试验土柱,进行优先流条件下胶体-重金属共迁移土柱淋滤试验,分析得到胶体-重金属共迁移规律。试验结果表明,胶体对重金属的吸附能力明显高于粉质黏土。有胶体情况下,镉出流量是无胶体情况下镉出流量的1.49倍,铅的出流量是无胶体情况下的33.88倍,有胶体情况下土上吸附的重金属和孔隙溶液中的重金属浓度都低于无胶体的情况,更多的重金属随胶体向下迁移,优先流条件下胶体明显加快了重金属的迁移。虽然铅的源浓度和淋滤时间都大于镉,但铅的出流量仅约为镉的1/13,由于易发生吸附,铅在土中的迁移能力较弱。     

The influence of surfactants on the adsorption of heavy metal ions by clays

The effect of a range of commercially available, water soluble surfactants on the uptake of Cu, Zn, Cd or Pb ions by three types of clay (kaolinite, illite and a montmorillonite) over the pH range 3–10 has been investigated. Charged surfactants influenced the phase distribution process when present at low concentrations (<0.005% w/v) but much higher levels of non-ionic species (> 0.1% w/v) were required to produce observable effects. The cationic surfactants reduced metal ion uptake by montmorillonite suspensions by competing for surface sites, but with illite and kaolinite the added organic cations had much smaller effects on the equilibrium position. The addition of anionic surfactants led to increased metal loss from solution, particularly in the presence of an alkyl benzene sulphonate. It is considered that the controlling process in this case was precipitation of sparingly soluble metal-surfactant species. The effect of the non-ionic organics (all ethoxylates) varied with the type of clay involved and the metal ion studied. The concentrations used were of the order required for micelle formation, and it is considered that the micelles became involved in the metal ion distribution process. With montmorillonite suspensions, the presence of surfactant reduced the amount of metal ion sorbed by the solid, but with kaolinite and illite evidence of a reduction in adsorption site availability was apparent in only a few of the systems examined. Of the remainder, many had no effect but twice this number caused some enhanced loss of metal ion from solution. Few of the added surface active agents significantly influenced the pH at which the metal ions precipitated as hydroxy species. The implication of the results on metal ion levels in natural waters has been considered.     

Removal of metal ions from aqueous solution by polysaccharide produced from Bacillus firmus

This paper deals with adsorption of Pb, Cu and Zn on the polysaccharide produced by Bacillus firmus. The adsorption of metal ions was significantly affected by the initial pH of solution, initial metal ion and polysaccharide concentrations, and presence of other ions in solution. At optimum pH, the uptakes of Pb, Cu and Zn were 98.3%, 74.9% and 61.8%, respectively. The metal ions removal was lower at neutral and generally the initial adsorption rate was rapid and reached equilibrium after 10 min. The process of uptake obeys both Langmuir and Freundlich isotherms.     

拱型波纹钢屋盖结构动力特性分析

拱型波纹钢屋盖结构具有自重轻、造型优美、造价低、施工便捷等优点，是一种值得推广的结构形式。目前，国内外对这种结构的静力性能研究较多，而动力分析结果在相关刊物上并不多见。按照拱计算模型，对这种结构的动力特性进行了分析，提出了一种简捷快速的计算方法，并讨论了结构参数对结构动力特性的影响。     

A five-year study on the heavy-metal pollution of Guanabara Bay sediments (Rio de Janeiro, Brazil) and evaluation of the metal bioavailability by means of geochemical speciation

Surface sediments of the Guanabara Bay (Rio de Janeiro, Brazil) were analyzed by a sequential extraction procedure for Cd, Cr, Cu, Pb, Zn, Mn and Fe, determining their distribution among five geochemical phases and in the nitric acid extractable phase. Bioavailable phases and non-bioavailable phases have been determined in six transects in the bay to define the significant level of pollution due to sediment metal contamination. A multiple correlation showed limited responsibility of Mn and Fe oxides and humic acids in the adsorption process, which allowed discrimination among the different processes and suggested the strong influence of the hydrogen sulfide present in the highly reduced bay bottom environment. The authors suggest the need to avoid disturbing bottom sediment by dredging or by artificial bottom aeration which could result in a rapid worsening of the environment due to the accelerated formation of more soluble oxygenated metal compounds making the toxic metals much more available to the benthic fauna and to the bay biota in general.