Heavy metal removal from aqueous solution using carbonaceous K_2S-impregnated adsorbent

A novel carbonaceous adsorbent for heavy metal removal was prepared from raw coal by one-step simple sulfur impregnation using K2S. Raw coal was mixed with K2S powder and then heated at 800℃ for 30 min in nitrogen to produce K2S char. The sulfur content and form in K2S char were determined, and the ability of K2S char to adsorb Zn^2＋, Cd^2＋ and Pb^2＋ was examined. The K2S impregnation was effective at impregnating sulfur into coal, especially in the form of elemental, thiophenic and sulfatic sulfur. The sulfur content of K2S char was higher than those of raw coal and pyrolysis char. The Zn^2＋ removal in 2.4 mmol/L of Zn^2＋ solution by K2S char was higher than raw coal with the removal rate of 100%. K2S char adsorbed Pb^2＋ and Cd^2＋ in 24 mmol/L of Pb^2＋ and Cd^2＋ solution with the removal rate of 97% and 35%, respectively. The elution extents of adsorbed Pb^2＋ and Cd^2＋ were zero in distilled water and 27% in 0.1 mol/L HCl solution. These results indicated that an effective adsorbent for heavy metal ions was prepared from coal using K2S sulfur impregnation, and that the adsorbed metals were strongly retained in K2S char.

Facile fabrication of spherical flower-like Mg(OH)2 and its fast and efficient removal for heavy metal ions

Spherical flower-like Mg(OH)_(2) was fabricated from MgSO_(4) effluent and its adsorption performance for heavy metal ions was evaluated.The appropriate fabrication conditions are as follows:Mg^(2+)/NH4OH molar ratio of 1:0.5,temperature of 120°C and time of 1 h at Mg^(2+)concentration of 2 mol/L.Spherical flower-like Mg(OH)_(2) composed of ultra-thin sheets exhibits an excellent adsorption ability for Ni^(2+),Cu^(2+),Zn^(2+),Pb^(2+),Fe^(3+)and Co^(2+),and the adsorption reaches the equilibrium in 6 min.The maximum adsorption capacities of the studied heavy metal ions onto Mg(OH)_(2) at 20°C are 58.55,85.84,44.94,485.44,625.00 and 27.86 mg/g,respectively.The adsorption is well fitted by the Langmuir model,indicating that the adsorption is monolayer.The adsorption kinetics follows the pseudo-second-order model.Chemisorption is the operative mechanism.Spherical flower-like Mg(OH)_(2) is a qualified candidate for heavy metal ions removal.

虾青素对镉离子(Cd^(2+))诱导下斑马鱼胚胎抗氧化指标的影响

(28.0±0.5)℃下,将100个产后1 h的斑马鱼(Danio rerio)胚胎放在120 mm培养皿中,暴露在<0.02%浓度的二甲基亚砜(DMSO,对照组)、50μg/L Cd^(2+)(低浓度暴露组)、500μg/L Cd^(2+)(高浓度暴露组)和Cd^(2+)+雨生红球藻(Haematococcus pluvialis)虾青素AST联合暴露组(50μg/L Cd^(2+)+100μg/L AST组和500μg/L Cd^(2+)+100μg/L AST组)5个处理组中,120 h后测定斑马鱼幼鱼活性氧(ROS)、丙二醛(MDA)和谷胱甘肽酶(GSH)含量、超氧化物歧化酶(SOD)活性和总抗氧化能力(T-AOC),研究重金属镉离子(Cd^(2+))暴露下斑马鱼胚胎的抗氧化响应,探讨AST对斑马鱼机体氧化损伤的缓解效果。结果表明,斑马鱼胚胎Cd^(2+)暴露120 h后,体内活性氧(ROS)和丙二醛(MDA)含量随着Cd^(2+)浓度的升高而增加;GSH含量、SOD和T-AOC的活性随着Cd^(2+)浓度的增加而降低。说明Cd^(2+)可诱导斑马鱼机体出现氧化应激和氧化损伤。添加AST后,斑马鱼幼鱼体内ROS和MDA含量下降,GSH含量、SOD和T-AOC活性上升,说明添加AST可在一定程度上缓解重金属Cd^(2+)对斑马鱼体内抗氧化指标的负面影响。本研究结果可为AST作为新型鱼类饲料添加剂提供理论依据。

Extraction of Heavy Metals from Solid Material by Supercritical CO_2

Extraction of heavy metal ions from solid matrix by means of an incorporation of chelating agents with supercritical carbon dioxide（scCO2） was investigated experimentally. Four commercially available chelating agents, diethylammonium diethyldithiocarbamate（Et2NH2DDC）, trifluoroacetylacetone（TFA）, hexafluoroacetylacetone（HFA） and thenoyltrifluoroacetone（TTA） were tested. The extraction experiments were conducted at 50 °C and 1.39×107― 2.80×107 Pa. According to the experimental results, for the extraction of Cu2＋, all the chelating agents investigated here are effective. For other metal ions, such as Pb2＋, Ni2＋ and Cd2＋, Et2NH2DDC exhibited a better extraction result, while other chelating agents were less effective. This investigation is expected to provide a tentative evaluation on the scCO2-based metal extraction from solid media.

TiO2 nanoparticles in aquatic environments:impact on heavy metals distribution in sediments and overlying water

The extensive application of TiO_(2)nanoparticles(NPs)highlights the importance of investigating their influence on aquatic systems.In this work,the effect of TiO_(2)NPs on heavy metals speciation was studied on a lab scale.For this goal,a series of aquaria containing water,sediment,and TiO_(2)NPs with various concentrations were set up.The study results revealed that TiO_(2)NPs caused(copper)Cu,(mercury)Hg,(titanium)Ti,and(zinc)Zn to be adsorbed by sediments in the forms of exchangeable and Fe-Mn species.According to measurements,30μg/L of TiO_(2)NPs made Cu,Hg,Ti and Zn concentration in the water column decreased from 33,1.14,20,and 32 to 4,0.58,3,and 22.3μg/L,respectively.Manganese(Mn)was also adsorbed by sediment,and in all experiments,its concentration in the water column reduced from 44 to about 20μg/L.Due to the photocatalytic capacity of TiO_(2)NPs,arsenic(As)concentration in the water column increased from 0 to 8.7μg/L with the introduction of30μg/L of TiO_(2)NPs.The sequential extraction results showed that in all experiments,concentrations of lead(Pb),nickel(Ni),and cobalt(Co)remained constant in different chemical species of sediment,which meant conservative behavior of them in presence of TiO_(2)NPs.In addition,a remarkable change was observed in water quality parameters such as ORP,TDS,TOC,BOD,NO3’and PO_(4)after the introduction of TiO_(2)NPs to aquaria.The reason behind these changes could be related to the decomposition of sediment organic content by TiO_(2)NPs.

Influences of Organic Acids and Heavy Metals on Cr（VI） Photoreduction Catalyzed by TiO2 Suspension

Photocatalytic reduction of Cr（VI） by TiO2 suspension has been studied with the purpose of removing the toxic and carcinogenic Cr（VI） ions from water. The photocatalytic reduction was carried out in batch reactor, in which the influences of the presence ofmalonic and oxalic acids as well as of iron and lead ions on the degree of the reduction have been systematically evaluated. The results of the research indicated that the presence of malonic and oxalic acids with increasing concentration can improve the photoreduction. The increase in the Cr（V1） photoreduction is due to OH radical capturing by the organic acids so that it prevents the recombination of the OH radical and the free electron, and therefore can provide enough electron supply for Cr（VI） photoreduction. The effectiveness of Cr（VI） photoreduction is also enhanced by the addition of increasing concentration of both Fe（Ⅲ） and Pb（Ⅱ） ions through synergic effect. It is also found that the degree of the photopreduction is strongly influenced by solution acidity and the most effective Cr（VI） photoreduction is obtained at lower pH than 5, either in the absence or presence of the organic acids and the heavy metal ions.

Comments on“Adsorption behavior of heavy metal ions by carbon nanotubes grown on microsized Al_2O_3 particles”

Recently, Hsieh and Horng [1] published the paper entitled as above. In section 3 results and discussion, the authors mentioned the first and the second order kinetic models without any quotations. In fact these two kinetic models have been published [2-5]. In order to distinguish a kinetics model based on the ad- sorption capacity of a solid from the one based on the concentration of a solution, Lagergren＇s first-order rate equation has been called pseudo-first-order [6-7]. The Lagergren＇s equation has been widely cited, but there are far more mistakes made in the quotation and in the reference section of papers, including the title, the author＇s name, journal title, year of publishing, volume, and page number [3]. In addition, the second order kinetic expression for the adsorption systems of divalent metal ions using sphagnum moss peat has been reported by Ho [8].

Cd^(2+)污染对水花生生理生化及超微结构的影响

1 引言 自1935年日本发生因镉中毒而导致的骨痛病以来,镉污染越来越受到人们的重视.有关其对人类及其它生物的危害已进行了很多研究[3,8,12].对水生植物而言,多数工作集中在对生理生化毒害[2,7]或对细胞结构损伤[7]的个别研究.笔者认为把生理生化变化与结构的破坏联系起来.讨论两者变化的相互关系,探讨其本质,才符合此过程的实际,则更具现实意义.但这方面的研究在国内还不多见.

重金属Pb^2＋和Cd^2＋对毛竹种子萌发及幼苗早期生长的影响

以毛竹种子为试材,研究不同浓度铅离子(Pb2+)、镉离子(Cd2+)对毛竹种子萌发和幼苗早期生长的影响。结果表明:随着Pb2+和Cd2+浓度的增加,毛竹种子的发芽率呈现出先升高后降低的趋势,发芽指数、活力指数均与浓度呈负相关关系;同时,Pb2+和Cd2+对幼苗根伸长、芽伸长及生物量积累等指标具有显著的抑制作用,并且这种抑制作用随着浓度的升高而增强,尤其是根部,根伸长抑制率最高分别达到96.20%和94.00%;幼苗地上部分与地下部分对Pb2+、Cd2+的积累随着胁迫强度的增加而升高,但地下部分的积累量要显著高于前者,相同浓度下最高差距分别达到地上部分的27.21、6.25倍。

黄泥土不同粒径微团聚体对Cd^(2+)的吸附与解吸研究

对采自太湖地区黄泥土进行了低能量超声波分离,采用平衡吸附法研究了不同粒径微团聚体颗粒对重金属Cd2+的吸附和解吸特点.结果表明,不同粒径微团聚体对Cd2+的吸附特性均符合Freundlich方程,模拟方程得到的K值介于152~503之间,以粘粒级和粗砂级为最大.微团聚体对Cd2+的吸附容量与其中游离氧化铁含量、CEC呈显著正相关.不同微团聚体Cd的解吸特点不同,粘粒级的解吸率仅为8.4%,远远低于其它粒径的微团聚体,这些结果有助于了解田间条件下土壤重金属化学行为和微观尺度的化学过程.

重金属Cd^(2+)和Cu^(2+)胁迫下泥蚶消化酶活性的变化

为了探讨重金属Cd2+和Cu2+胁迫对泥蚶消化酶活性的影响,运用酶学分析的方法,按《渔业水质标准》(GB 11607)规定的Cd2+、Cu2+最高限量值的1、2、5、10倍设置重金属离子Cd2+、Cu2+浓度及其组合,研究了在重金属Cd2+、Cu2+胁迫下,30d内泥蚶3种消化酶活性的变化规律。结果表明:与空白对照组相比,在重金属Cd2+、Cu2+或其组合的胁迫下,较低浓度组泥蚶的淀粉酶活性实验前期增强(即被诱导),实验后期减弱(即被抑制),较高浓度组泥蚶的淀粉酶活性从实验一开始就减弱,并保持在较低水平,毒性比较,同一重金属高浓度>低浓度,不同重金属及其组合Cu2+>(Cd2++Cu2+)组合>Cd2+;泥蚶脂肪酶的活性实验前期增强,实验后期转为微减弱或减弱,毒性比较,同一重金属高浓度>低浓度,不同重金属及其组合(Cd2++Cu2+)组合>Cu2+>Cd2+;泥蚶胃蛋白酶的活性实验前期增强,且活性呈现升高-降低-再升高-再降低的变化,实验后期分别表现微增强、微减弱和减弱,毒性比较,同一重金属高浓度>低浓度,不同重金属及其组合(Cd2++Cu2+)组合>Cu2+>Cd2+。可见:环境中的Cd2+和Cu2+对泥蚶的消化酶活性起着明显的影响作用。

天然锰钾矿处理含Cd^(2+)废水实验研究

利用天然锰钾矿处理实验室内配置的含Cd2 + 废水 ,结果表明 :天然锰钾矿对水溶液中Cd2 + 的去除达平衡需 2d以上 ;锰钾矿粒径越小对Cd2 + 的去除量越大 ;溶液中Cd2 + 的浓度不太高时 ,去除量随溶液浓度的升高而增大 ;在酸性介质中去除量随pH值增大先降低后增大 ,pH值超过 6 .3时天然锰钾矿表面开始带负电荷 ,在弱碱性介质中去除量最大 ;不同电解质对去除量的的影响主要是由Cl-与Cd2 + 的络合造成的。实验浓度范围内能很好地用Lang muir吸附等温线拟合 ,对Cd2 + 的最大吸附量为 5 .5 4mg/ g。锰钾矿处理含Cd2 + 废水的过程中伴随有K+ 和Mn2 + 溶出。处理Cd2 + 后的锰钾矿渣 ,经超声并淋滤后仍有大部分的Cd2 + 被固持 ,固持率可达去除量的 79.82 %。

PAM包覆改性硅藻土吸附模拟废水中的Cd^(2+)

研究用PAM包覆改性硅藻土并应用于处理含Cd2+模拟废水。探究了PAM浓度、pH值以及初始浓度的变化对改性硅藻土吸附Cd2+的影响。结论表明:与原土相比,改性硅藻土对酸性重金属废水的适应性增强,pH值为1.5时,改性硅藻土吸附(C0=200 mg/L)Cd2+的吸附容量是原土的2.75倍;改性硅藻土对高浓度的Cd2+废水去除效果比原土更好;改性后硅藻土的表面结构性能得到增强,有利于吸附带正电Cd2+;SEM结构表征表明,改性硅藻土表面光滑,杂质较少,PAM以分子层形式吸附在硅藻土的表面及其孔隙内。

膨润土对重金属离子Pb^(2+),Zn^(2+),Cr(VI),Cd^(2+)的吸附性能

试验研究了pH值、吸附时间和吸附剂用量对膨润土吸附重金属离子Pb2+,Zn2+,Cr(VI)和Cd2+的影响.结果表明,在本试验的pH值、吸附时间及吸附剂用量条件下,膨润土对Pb2+,Zn2+,Cd2+的吸附效果均优于其对Cr(VI)的吸附效果;pH值是影响上述吸附的重要因素,离子交换和表面络合是上述吸附的主要形式.

AMPS改性凹凸棒土的制备及其Cd^(2+)吸附研究

为提高凹凸棒土对重金属离子的吸附能力以及改善其在有机溶剂中的分散性能,本研究以硅烷偶联剂KH-570为改性剂,对凹凸棒土进行初步有机改性后再与阴离子单体2-丙烯酰胺基-2-甲基丙磺酸(AMPS)进行双键加成反应,制备了1种新型有机改性凹凸棒土。利用红外光谱(FT-IR)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、X-射线衍射(XRD)、热重分析(TG)等手段对改性凹凸棒土进行了结构表征,并对其Cd^(2+)吸附性能进行了研究。结果表明,该新型有机改性凹凸棒土在结构上未因改性而发生破坏,但其对重金属离子的吸附性能却有了很大幅度的提高,其中Cd^(2+)的吸附率可达66%,且在N-N二甲基甲酰胺、二甲基亚砜、甲醇等有机溶剂中的分散性明显提高。

Cd^(2+)对二化螟生长发育及雄蛾对性信息素定向行为的影响

本文采用室内添加含6个不同浓度Cd^(2+)[0(对照)、1 mg/kg、5 mg/kg、10 mg/kg、15 mg/kg、20 mg/kg]的人工饲料的方法饲养二化螟Chilo suppressalis(Walker)2龄幼虫,测定二化螟的生长发育和雄蛾对性信息素的定向行为,研究稻田重金属镉(Cd^(2+))污染对二化螟生长发育及定向行为的潜在影响。结果表明:二化螟的生长发育和雄蛾对性信息素定向反应率受到了Cd^(2+)的影响。其中取食含Cd^(2+)人工饲料后,二化螟幼虫历期延长3.4-21.9 d,蛹历期缩短0-2.3 d,化蛹率及羽化率分别降低1.9%-35.7%和13.6%-44.9%;低浓度Cd^(2+)(1-10 mg/kg)处理后雌、雄蛹重分别增重4.3-4.8 mg和0.8-3.8 mg,高浓度Cd^(2+)(15-20 mg/kg)处理后雌、雄蛹重分别减轻0.2 mg和5.2 mg;高浓度Cd^(2+)处理的雄蛾接近正常求偶雌蛾的百分率低于它们接近Cd^(2+)处理后求偶雌蛾的百分率,而低浓度Cd^(2+)雄蛾接近正常雌蛾、Cd^(2+)雌蛾的百分率与对照组无显著差异。另外,正常雄蛾接近Cd^(2+)处理后求偶雌蛾的百分率未受显著影响。

天然及改性膨润土吸附废水中Pb^(2+)、Ni^(2+)、Cd^(2+)的试验研究

用山东潍坊涌泉某膨润土厂生产的天然钙基膨润土和改性膨润土对模拟含Pb2+、Ni2+、Cd2+的废水分别进行了试验研究。结果表明,该厂的天然钙基膨润土和改性膨润土对废水中的Pb2+、Ni2+、Cd2+有较高的去除率,可以作为重金属离子Pb2+、Ni2+、Cd2+的吸附剂使用。

离子液体-超声波辅助萃取火焰原子吸收法测定油画棒中的可迁移微量Cd^(2+)

以离子液体为萃取介质,超声波辅助萃取油画棒中的可迁移微量Cd2+,以硝酸溶液反萃取后用火焰原子吸收法测定镉。考察了主要影响因素对萃取效果的影响。结果表明,以1-丁基-3-甲基咪唑六氟磷酸盐离子液体为萃取介质,溶液pH值为9.0、金属螯合剂用量为2.00 mL、离子液体的用量为2.00 mL、反萃剂为4.00 mL 1.00 mol.L-1硝酸、超声时间为5 min时,萃取率可达99%,富集倍数为25,除Cu2+、Pb2+外其它干扰离子对Cd2+的萃取影响不大。方法的加标回收率为96%～103%,相对标准偏差(n=11)为1.7%,检出限为0.016 mg.L-1。

重金属Zn^(2+)·Cd^(2+)对田菁生理生化指标的影响

[目的]研究重金属Zn2+、Cd2+对田菁生理生化指标的影响。[方法]以田菁幼苗为试验材料,在水培条件下,研究了Zn2+、Cd2+对田菁幼苗生理上的毒害。[结果]Zn2+、Cd2+对田菁幼苗毒害作用显著。随着Zn2+、Cd2+胁迫浓度的增高,田菁叶片叶绿素含量表现为先增高而后降低的趋势;可溶性蛋白含量表现为下降趋势;脯氨酸含量表现为上升趋势;SOD与POD活性表现为先升高而后降低的趋势。Zn2+、Cd2+对田菁幼苗的毒害作用强度不同,Cd2+表现出更强的毒害作用。[结论]该研究为了解海滨地区的重金属污染状况,治理生态环境提供了参考依据。

纤维素基水凝胶的辐射合成及其对水体中Cd^(2+)吸附性能研究

采用丙烯酸、丙烯酰胺为主要单体,通过^(60)Co-γ射线辐射引发纤维素接枝,制备纤维素基重金属吸附材料。考察了纤维素种类、添加量及溶液pH对重金属Cd^(2+)的吸附容量及去除率的影响。结果表明,最佳合成条件为:辐照剂量5 kGy,剂量率2 kGy/h,丙烯酰胺∶丙烯酸=3∶1,纤维素占固含量的重量百分比为17.85%。在该条件下得到自制纤维素(17.85%SMC)及微晶纤维素(17.85%MCC)接枝聚合物,在Cd^(2+)溶液pH=7时,吸附容量分别为44.29 mg/g,42.09 mg/g。17.85%SMC经5次循环,Cd^(2+)吸附容量>40 mg/g,去除率>80%。FTIR、SEM-EDS、TGA分析表明,主要单体成功接枝到纤维素上并形成酯基,纤维素添加量为17.85%时纤维素接枝聚合物保持良好的热稳定性,其Cd^(2+)吸附效果最佳。