Wood sawdust and wood originate materials as adsorbents for heavy metal ions

The abilities of different types of wood sawdust and wood originate materials for removing some toxic heavy metal ions from water were investigated. Sawdust of poplar, willow, fir, oak and black locust wood, pulp and Kraft lignin were used as adsorbents. The effects of contact time, pH, metal concentration and sawdust particle size on the removal of Cu(II) ions by poplar sawdust have been studied. Leaching from these adsorbents into water during adsorption was also investigated.     

Proteins and protein-rich biomass as environmentally friendly adsorbents selective for precious metal ions

Proteins exhibit specific interactions with various metal ions, which play important roles in a living cell. Here, we found that various proteins selectively adsorbed precious metal ions at a wide range of pH values. Studies on protein sequences and on synthesized peptides revealed that a histidine-containing sequence had specific interactions with precious metal ions (Au3+ and Pd2+). We then investigated a few types of protein-rich biomass as adsorbents for precious metal ions. In the presence of various transition metal ions, Au3+ and Pd2+ were also selectively adsorbed onto the biomass tested. The bound precious metal ions were recovered by aqua regia after charring the metal-bound biomass. Finally, we demonstrated the successful recovery of Au3+ and Pd2+ from a metal refining solution and a metal plating waste using the biomass. We propose an environmentally friendly recycling system for precious metal ions using protein-rich biomass.     

氧化石墨烯基材料吸附重金属离子的研究进展

废水中所含的重金属离子对自然环境和人体健康造成了极大危害。在众多处理方法中,基于氧化石墨烯(GO)基材料吸附重金属离子的方法受到研究者关注。梳理近年来的研究文献,重点论述GO、不同GO基纳米复合材料、磁性氧化石墨烯(MGO)基纳米材料及还原氧化石墨烯(rGO)基材料的合成方法、重金属离子吸附概况等,通过结构表征及吸附热力学和动力学机理分析,为进一步研究、设计氧化石墨烯材料及处理重金属离子奠定基础。     

用于中草药重金属去除的吸附材料的研究进展

吸附法在中草药的重金属去除中是一种可靠而有效的处理手段。本文主要对壳聚糖、麦饭石、海藻、吸附树脂及天然纤维素类物质等几种吸附材料在中草药去除重金属领域中的研究新进展进行综述。     

重金属检测荧光传感技术的研究进展

重金属离子是一类极具生理毒性的化学物质,其检测方法在化学传感领域引起了人们广泛的关注,而食品中重金属离子的检测也愈发重要。荧光探针因具有组织穿透性、低背景荧光干扰、高效灵敏和检测实时便捷等特点,成为重金属检测的重要手段之一。文中综述了近年来主要重金属离子检测荧光探针(香豆素类,罗丹明类、喹啉类和比率型)的研究进展,重点分析荧光探针的设计原理,检测机制及其结构与化学传感的关系,为荧光探针识别重金属的应用提供指导。最后展望了荧光探针在食品检测、环境监测和生物成像等领域的发展趋势和应用前景。      

Sewage sludge-derived materials as efficient adsorbents for removal of hydrogen sulfide

Sewage sludge-derived materials were used as adsorbents of hydrogen sulfide from moist air. The adsorbent obtained by carbonization at 950 degrees C has a capacity twice of that of coconut-shell-based activated carbon. The capacity of the sludge-derived materials increases with increasing carbonization temperature. It is likelythatduring carbonization at 950 degrees C a mineral-like phase is formed that consists of such catalytically active metals as iron, zinc, and copper. The results obtained demonstrate that the presence of iron oxide significantly increases the capacity of commercial carbon and activated alumina. The sludge-derived adsorbents are efficient for hydrogen sulfide removal until the pore entrances are blocked with sulfur as the product of oxidation reaction. For materials in which the catalytic effect is predominant, hydrogen sulfide is adsorbed until all pores are filled with sulfur. There is also indication that chemisorption plays a significant role in the removal of hydrogen sulfide from moist air.     

木浆生产线的备木技术

介绍了当前广泛应用的备木生产线中原木剥皮、削片、木片筛选、过大木片再碎、木片贮存、树皮及木屑处理以及原木冲洗等系统的特点,通过分析不同剥皮鼓的喂料及卸料方式、不同削片机的喂料及卸料方式以及各种备木生产设备运行的情况,对备木设备的改进以及设备布置的方式提出了一些建议。     

电化学和光纳米探针技术用于重金属离子快速检测的研究进展

随着现代工业的快速发展,重金属污染问题日益严重,对人类健康造成了严重威胁,因此发展快速、灵敏、准确、易携带的重金属离子检测方法至关重要。电化学分析作为一种特殊的化学分析方法,因其选择性好、操作安全、分析简便的优点被应用于食品检测、环境监测、生物医疗各方面。光纳米探针技术在检测分析物质时,具有灵敏度高、选择性好、操作简便的优点。电化学分析法和光纳米探针技术在检测重金属离子时,克服了传统重金属方法检测流程烦琐、检测成本高、操作过程复杂、操作要求高的不足,成为当前重金属离子快速检测的研究热点。因此,本文对重金属污染现状、电化学和光纳米探针技术检测重金属的原理以及研究进展进行阐述,并对其未来发展趋势进行展望,以期帮助检测人员优化改进检测方法,为重金属离子的快速检测提供方法上的支持。     

Rapid method for detection and detoxification of heavy metal ions in water environments using phytochelation

Phytochelatins (PCs, (gammaGlu-Cys)n-Gly (n = 2-11)) are produced by higher plants, algae, and some fungi in response to heavy metal ion exposure. A rapid and convenient method for quantifying heavy metal ion concentrations in water environments was developed using a chemically synthesized PC as a mediator. The chelating ability of the PC and quantification of the thiol group were utilized to measure heavy metal ions at low concentrations. The method requires only ten minutes for measurement and only 1 ml of a liquid sample. A range of homogeneous PCs (n = 4-7) were chemically synthesized using a peptide synthesizer. These, especially PC7, exhibited higher sensitivity and consistency of measurement than the native PC from Silene cucubalus, which produced a mixture of PC2, PC3, and PC4. Detoxification of heavy metal ions in vitro by PC was also investigated. Using the paper disc method, the cell growth inhibition zone caused by cadmium ion against Salmonella typhimurium TA1538 was significantly decreased by addition of PC. Furthermore, at the minimum inhibitory concentration of cadmium ion (200 microM) in a nutrient broth culture of S. typhimurium, cell growth was almost completely recovered by addition of PC to the medium.     

水溶性膳食纤维对乳酸菌增殖及重金属离子吸附研究

探讨了经过物理场-酶法制备的六种豆渣水溶性膳食纤维(SDF)对乳酸菌的增殖作用,以及在生理条件下(37℃,pH=2、pH=7)对重金属离子Pb2+、Hg2+、Cd2+的吸附作用。实验结果表明,在培养基中添加六种水溶性膳食纤维对保加利亚乳杆菌和乳酸片球菌都具有一定的促进增殖作用。对保加利亚乳杆菌的促进增殖作用更显著,主要体现在提高最大生长量和延长稳定期,延缓衰老期;水溶性膳食纤维对重金属离子的吸附能力在模拟小肠环境下远远好于模拟胃环境,在两种酸度条件下,对Pb2+、Cd2+的吸附效果较好,对Hg2+的吸附效果较差。     

淀粉基重金属捕集材料的合成及捕集效能

以天然淀粉为原料,采用逐步分子修饰合成淀粉基重金属捕集材料,并对产品的铜镍离子捕集能力进行了评估分析。首先淀粉分子通过醚化作用,引入阳离子季铵型基团;在此基础上,继续磷酸化引入阴离子基团;合成过程添加尿素,促进各类基团的交联网状结构,淀粉分子的氨基甲酸酯化同时也引入非离子基团,最终获取了多种电荷分布的淀粉分子修饰产品。研究结果表明,3-氯-2-羟丙基三甲基氯化铵(CHPTAC)用量为淀粉质量(m L/g)0.4,50℃下作用4 h,阳离子化取代度最高为1.61%。三聚磷酸钠质量分数4%,p H值6~7,120℃下作用2 h,负电荷磷酸化淀粉分子的取代度为0.026。低浓度的尿素能提高磷酸化淀粉的反应效率,质量分数高于3%时,会与淀粉分子氨基甲酸酯化作用增强结构的交联。不同基团取代度的产品对铜镍离子均具有捕集效果,阳离子化和阴离子磷酸酯化的取代度分别为1.42%和0.018,淀粉基捕集材料对30 mg/L浓度含铜、镍离子溶液的重金属去除率高达98%。     

纳米传感器检测重金属离子的研究进展

近年来各类重金属离子污染受到广泛关注。传统的重金属离子监测体系主要依赖于专业的仪器设备,操作费时、设备昂贵、现场快速检测的及时性差、难以满足当前检测工作的需要。鉴于重金属离子检测分析的重要性和紧迫性,寻求简单、快捷的检测方法具有重大的现实意义。随着纳米技术的飞速发展,把纳米材料与光学、电化学、生物学及材料技术结合构建的纳米传感器促进了重金属离子检测技术的快速发展。本文对近几年来常用的几种纳米传感器在重金属检测应用中的研究进展进行了综述,包括:纳米光学传感器、纳米电化学传感器、纳米生物传感器等。本文对基于纳米传感器的检测手段进行了讨论和展望,旨在为重金属离子检测研究的发展提供参考。     

酿酒废酵母吸附共存重金属离子的研究

为研究酿酒废酵母吸附共存重金属离子的可行性,在单因素试验的基础上,采用响应曲面法探讨酿酒废酵母吸附共存离子Pb2+、Ni 2+、Cu2+的最佳工艺条件。结果表明:酿酒废酵母对共存重金属离子Pb2+、Ni 2+、Cu2+吸附的最佳条件为pH值3.15,吸附温度30℃,吸附时间60min,酵母浓度2.04g/L,离子浓度61.34mg/L,该条件下酿酒废酵母对共存离子的吸附率为62.78%。     

Modification of sawdust from pine and beech wood with the succinic anhydride

The aim of this study was to compare the reactivity of the succinic anhydride with the comminuted softwood (Pinus sylvestris L.) and hardwood (Fagus sylvatica L.). By extending the time of reaction (from 4 to 8 hours), products with different degrees of modification were obtained. It was demonstrated that in comparison with beech wood, the wood of Scots pine enters the reaction with the succinic anhydride easier. The results of the thermogravimetric analysis showed that the esterification of softwood and hardwood reduced the initial temperature of their thermal degradation. Wood modified with the succinic anhydride is characterised by poorer thermostability in comparison with natural wood.     

重金属离子铜、铝在锦鲤鱼幼鱼体内积累的研究

通过对锦鲤鱼(Cyprinus carpioi)幼鱼进行混合重金属积累的实验,研究了锦鲤鱼暴露在重金属铜(Cu)、铅(Pb)的混合溶液下,体内的积累规律.结果表明,锦鲤鱼对铜(Cu)、铅(Pb)的富集规律性较强,在积累实验中,锦鲤鱼体内各种重金属含量随着时间的推移明显呈上升趋势.锦鲤鱼积累2种重金属的总趋势是Pb＞Cu.在相同部位中,2种重金属的积累量随浓度的增加而增大;在同一浓度下,内脏、鳃和肌肉中两种重金属的积累量有较大差异,其积累能力为内脏＞鳃＞肌肉,且内脏中的积累量比鳃和肌肉中积累量大很多.     

Sorption studies of Zn(II)- and Cd(II)ions from aqueous solution on treated sawdust of sissoo wood

Sawdust, an inexpensive material, has been utilized as an adsorbent for the removal of Zn(II)- and Cd(II)ions from aqueous solution. The effects of time of equilibrium, pH, temperatures and dosage of the adsorbent on the removal of Zn(II)- and Cd(II)ions have been studied. The equilibrium nature of Zn(II)- and Cd(II)ions adsorption at different temperatures (25–60 °C) has been studied. The percent adsorption of Zn(II)- and Cd(II)ions increased with an increase in pH, temperature and dosage of treated sawdust. The applicability of the Langmuir isotherm suggests the formation of monolayer coverage of Zn(II)- and Cd(II)ions at the surface of the adsorbent. The thermodynamic parameters like free energy, enthalpy and entropy changes for the adsorption of Zn(II)- and Cd(II)ions has also been computed and discussed. The heat of adsorption [ΔH=17.706 kJmole^-1 for Zn(II) and ΔH=16.949 kJmole^-1 for Cd(II)] implied that the adsorption was an endothermic adsorption. The sawdust was found to be a metal adsorbent as effective as activated carbon.     

Support materials for yeast immobilization affect the concentration of metal ions in the fermentation medium

Hydrogels are potential absorbers of ions present in the medium, but they can also release some cations (e.g. calcium in calcium alginates). Polyelectrolytes such as alginic acid and poly(acrylic acid) strongly bind polyvalent metal ions. In this paper, the impact of some materials used for the immobilization of yeast, in particular the concentration of certain ions, especially those that play a significant role in the process of fermentation such as calcium, magnesium, zinc and manganese, was assessed. The support for the immobilization of yeast (calcium alginate and polyacrylate) significantly affected the concentration of metal ions in a model solution. Calcium alginate decreased the concentration of Mg²⁺, Zn²⁺ and Mn²⁺ in the solution by about 10–25%, and greatly increased the Ca²⁺ concentration. Polyacrylate, while swelling, decreased the concentration of cations present by up to 50%. Based on the results in this work, no supplementation of wort with divalent metal salts is advised, since it may lead to a stronger cross‐linking of polyelectrolytes used, and consequently result in a slower fermentation. Similarly, the relatively high concentration of calcium ions, caused by ion exchange, did not appear to affect the fermentation process. Copyright © 2013 The Institute of Brewing & Distilling     

Highly effective adsorption of heavy metal ions by a thiol-functionalized magnesium phyllosilicate clay

A thiol-functionalized layered magnesium phyllosilicate material (called Mg-MTMS), prepared by a direct and cost-effective co-condensation synthesis, has been investigated as a high-capacity adsorbent for heavy metal ions. Structural characterization by powder X-ray diffraction, infrared spectroscopy, solid-state 13C and 29Si NMR spectroscopies, and elemental analyses confirms the smectite-type structure and the high organic moiety content of this material. Mg-MTMS was found to be highly effective for the adsorption of Hg(II), Pb(II), and Cd(II) ions, exhibiting unprecedented metal ion uptake capacities of 603, 365, and 210 mg of metal/g of adsorbent, respectively. Mg-MTMS shows an equivalent affinity for the three metal ions, removing them from mixed metal solutions with an equal ion uptake capacity (approximately 400 mg of metal/g of adsorbent). Metal-loaded Mg-MTMS can be regenerated by acid treatment without altering the adsorbent properties. The high effectiveness of Mg-MTMS for the capture of metal ions is attributed to both the high concentration of complexing thiol groups (6.4 mmol of SH/g of Mg-MTMS) and the expansion capability of the framework, which facilitates the accessibility of the binding sites.