水合氧化铁对痕量铀的吸附行为

研究了水合氧化铁的制备条件及其对痕量铀的吸附行为，结果表明，当加碱温度和反应温度均为80℃时，吸附剂具有最大比表面积172．8m^2.g^-1，当吸附平衡时间为30min，吸附温度为90－95℃，溶液pH≈6时，铀吸附量可达122mg.g^-1，但吸附体系中硼酸和硫酸镁的存在导致铀吸附量下降。     

单核Zn(Ⅱ)水合和水解形态的量子化学计算

利用量子化学计算气相中锌离子各种水合和水解形态的几何结构、电荷分布以及水合和水解反应的Gibbs自由能变和焓变．结果表明,除了水合锌离子外,锌离子各种水解络合物的配位数均小于6;对于深度水解产物Zn（OH）3^-和Zn（OH）4^2-,内层无水分子的键合．水合作用和水解作用互相抑制,水合作用阻碍了水解产物进一步水解（Zn（OH）2除外）,水解作用使得水合变得困难．内层键合水分子数的增加降低了水合形态中Zn上的电荷,使得水解形态Zn上的电荷升高．     

蒙脱石吸附Cr3+、Cd2+、Cu2+、Pb2+、Zn2+的研究:pH值和有机酸的影响

粘土具有良好的离子交换和吸附特性，常被用作垃圾填埋场的衬层，吸附垃圾渗滤液中的氨氮及重金属离子，防止污染土壤和地下水。研究了pH值对蒙脱石吸附Cr^3 、Cd^2 、Cu^2 、Pb^2 和Zn^2 等五种重金属离子的影响，以及有化学络合剂EDTA和几种有机酸存在条件下，蒙脱石吸附Cr^3 、Cd^2 、Cu^2 、Pb^2 和Zn^2 五种重金属离子的效果。为了接近自然吸附状态，实验采用了离子交换柱进行连续吸附。结果表明，pH值对Cu^2 、Pb^2 和Cu^2 的吸附率影响极大；化学络合剂以及有机酸的存在降低了各重金属离子的吸附率，影响的强弱(设其符号为y)顺序为Y(Pb^2 )≤y(Cd^2 )≤y(Zn^2 )≤y(Cu^2 )≤y(Cr^3 )。     

改性不溶性淀粉黄原酸酯(ⅡSX)性能的研究

改性不溶性淀粉黄原酸酯是一种具有室温稳定性并对重金属离子有较高吸附率的廉价离子交换剂。其吸附容量为0.44—1.60mN/gIISX,该交换剂对锌离子的螯合比为2:1,对铬(Ⅲ),镍离子为1:1.用稀酸可使IISX再生,并同时回收重金属。     

钙型斜发沸石铵离子交换平衡的研究

测定了在不同pH值下人工改型所得钙型斜发沸石对NH4^ 的全交换容量、对NH4^ 的等温交换平衡曲线，进一步研究了其部分热力学特性。结果表明，钙型斜发沸石对NH4^ 交换总量随pH值的升高而降低，在pH值为7时为79．321mmol／100g，该离子交换过程可自发进行，且其选择性随温度的升高而降低。研究成果可为沸石法处理含氨氮废水的进一步研究提供一定的理论依据。     

高硬度矿泉水的软化研究

采用加药沉淀－离子交换法，结合实例对高硬度矿泉水进行软化研究。试验结果和工艺计算表明，加药沉淀－离子交换法对高硬度矿泉水具有良好的软化效果，方法简单、投资少，成本低，水质好等优点，是一种既能降低矿泉水的硬度和碱度，火能保持水中微量元素含量的理想方法。     

天然沸石对农田退水中氨氮的去除

利用静态吸附实验研究了沸石颗粒大小、氨氮初始浓度、接触时间及Na+离子浓度等因素对天然白银沸石去除模拟黄灌区农田退水中氨氮(NH4+-N)效果的影响,同时研究了吸附等温线特征,并考察了其吸附机理.研究结果表明,沸石颗粒大小、接触时间及NH4+和Na+初始浓度对NH4+-N交换容量都会产生一定影响;根据复相关系数(R2),NH4+-N的吸附等温线更符合三参数等温线模型;而对于两参数等温线模型,Langmuir模型比Freundlich模型能更好地描述NH4+-N在天然沸石上的离子交换过程;NH4+-N吸附实验数据与Elovich模型拟合最好(R2≥0.9766).研究结果表明了天然白银沸石是一种适合NH4+-N去除的离子交换剂,可用于黄灌区农田退水中NH4+-N的去除.     

超细高活性水合氧化钙的制备与表征

本文报告了制备超细高活性水合氧化钙过程中各种因素，包括添加剂的重量百分比，氧化钙径、氧化钙用量，搅拌速度，水浴温度，搅拌时间，添加剂等对吸硫剂比表面积的影响，在制得的超细高活性发氧化钙基础上，进行了一些物理化学特征的研究，如扫描电镜，Ｘ射线能谱分析主粒径分布等，并且在差热天平上进行了吸硫剂在高温下的吸硫机制的研究。     

水合二氧化锰界面特性及其除污染效能

研究了水合二氧化锰(δMnO2)的界面特性及其吸附性能.考察了δMnO2的比表面积、粒径分布、表面官能团及ζ电位;探讨了δMnO2对水中亚砷酸盐及腐殖酸的吸附去除效能.结果表明:δMnO2的比表面积为117.4m2·g-1,体积平均粒径为0.11μm;δMnO2表面具有丰富的表面羟基(Mn-OH);随着pH值由1.9升高至10.7,δMnO2的ζ电位由 22.7mV降低至53.5mV,其零电荷点在pH3.0附近.δMnO2对亚砷酸盐(As(III))及腐殖酸(HA)均表现出优良的吸附去除效能,其单位δMnO2质量的最大吸附量分别为137μgAs(III)·mg-1δMnO2和1.01mgTOC·mg-1δMnO2.亚砷酸盐与腐殖酸共存时,腐殖酸的存在使得亚砷酸盐的去除率下降10%—28%;而亚砷酸盐对腐殖酸的去除无明显影响.     

Nd-Er/ZnO-TiO_2光催化剂制备及对酸性品红的光催化降解效应

本研究采用溶胶凝胶法,以钛酸丁酯[Ti(OC_4H_9)_4]和六水合硝酸锌[Zn(NO_3)_2·6H_2O]为前躯体,六水合硝酸钕[Nd(NO_3)_3·6H_2O]与五水合硝酸铒[Er(NO_3)_3·5H_2O]为掺杂改性材料制备出稀土共掺杂的Nd-Er/ZnO-TiO_2光催化剂。以有机染料酸性品红为目标降解物,分别比较加入助催剂H_2O_2与未加助催剂H_2O_2在可见光下同Nd-Er/ZnO-TiO_2光催化剂一起对光催化活性的影响。降解实验表明,在可见光照射下,样品1%Nd-1%Er/5%ZnO-TiO_2具有较高的催化活性,其最佳煅烧时间和煅烧温度分别为2 h和550℃;H_2O_2在整个光催化反应体系中充当助催剂,与光催化剂产生协同效应,提高光催化降解酸性品红反应速度。本研究还利用X射线衍射仪(XRD)、比表面积分析仪(BET)、红外光谱仪(ATI-IR)对所制得的光催化材料进行表征。结果表明经稀土共掺杂改性后的ZnO-TiO_2光催化剂不仅粒径更小,比表面积也更大。     

Assessment of Cs and Sr accumulation in two epiphytic species of Tillandsia (Bromeliaceae) in vitro

Multiple nuclides commonly occur together and exert toxicity simultaneously, but the difference between single and combined effects of the nuclides is rarely investigated. Epiphytic Tillandsia species are efficient air pollution biomonitors, but rarely used to monitor nuclide contamination. Two Tillandsia species, that is, T. brachycaulos and T. stricta, were chosen to test their capacity to accumulate Cs and Sr. Most plants were able to endure Cs and Sr stress for a long period, which suggested these species could resist toxic elements physiologically and metabolically. With the increasing Cs or Sr concentrations, nuclide contents in both species increased significantly, indicating the potential of Tillandsia species in monitoring nuclide pollutants. However, when the plants were treated with combined nuclides, the content of each ion decreased distinctly compared to those treated with single ion, which suggested Cs and Sr influenced and inhibited each other. In addition, T. brachycaulos seemed more efficient in the uptake of Sr, while T. stricta was more efficient for Cs. Both species accumulated more Sr than Cs at low concentrations, while more Cs than Sr at high concentrations. These results indicated that the uptake of Cs and Sr was related to both the concentrations of the nuclides and the plant species exposed.     

麦饭石对Pb2+离子吸附的动力学研究

本文研究了水溶液中麦饭石对Ｐｂ＾２＋离子去除的反应动力学,考察了ＭＦＳ粒度、溶液ＰＨ值和铅离子的初始浓度对吸附反应的影响。结果表明,ＭＦＳ对Ｐｂ＾２离子具有较强的吸附性能,ＰＨ值是影响吸附的主要因素,Ｐｂ＾２＋离子吸附的最初速率与浓度符合一级反应动力学;吸附过程符合Ｌａｎｇｍｕｉｒ吸附等温式;离子交换和表面络合反应是主要吸附形式。     

钾改性蒙脱石磁性微球对铯的吸附性能

本研究以钙基蒙脱石(Ca-MMT)为原料,通过K⁺作用制得改性蒙脱石粉(K-MMT),经海藻酸钠交联作用,将改性蒙脱石与永磁体(BaFe₁₂O₁₉)结合,制成钾改性蒙脱石磁性微球(KMBC).对比了Ca-MMT、K-MMT、KMBC对Cs+的吸附差异,并通过SEM-EDS、FTIR、XRD、XPS分析了K-MMT的微观结构及理化性质.试验结果表明,K⁺对蒙脱石的改性以离子交换为主,改性后晶体层间距变小,吸附量K-MMT>KMBC>Ca-MMT,分别为57.08、45.13、45.05 mg·g^-1;K-MMT对Cs⁺的吸附属于吸热反应,反应在2 h内可达到平衡,35℃时KMBC的最大吸附量为136.08 mg·g^-1;随着pH的增加,KMBC对Cs+的吸附量呈先增大后减小的趋势;吸附机理主要包括离子交换和内层扩散.     

Cationic dye adsorption onto natural and synthetic zeolites in the presence of Cs+ and Sr2+ ions

Adsorption of diazine dye safranine O (SO) in the presence of Cs⁺ and Sr²⁺ ions was investigated onto natural and synthetic zeolites in order to predict competition of cationic organic species with their radionuclides, which are the main fission products released into the environment. Adsorption of SO was measured up to the 40th day and the surface-diffusion coefficients (D_s) were estimated by applying Nernst–Planck approximation based on a homogeneous-surface-diffusion model. The values of D_s were 10 times higher on natural zeolite than those of synthesized zeolite from fly ash (FA) under hydrothermal conditions. Similarly, distribution coefficients (K_D) were considerably higher on the clinoptilolite-type natural zeolite. The zeolitized product of FA is mainly composed of analcime and sodalite. SO adsorption on natural zeolite was not influenced by Cs⁺ and Sr²⁺ ions, but it decreased at high concentrations on synthetic zeolite. The higher influence of the Sr²⁺ ions on SO⁺ adsorption showed that they compete with each other for the same adsorption sites. These results suggested that natural zeolite cannot be used for remediation of wastewater polluted with Cs and Sr radionuclides in the presence of organic cations, whilst FA zeolite has a potential for Sr removal.     

Desorption technologies for remediation of cesium-contaminated soils: a short review

Environmental Geochemistry and Health - This review summarizes the mechanisms for desorbing and extracting cesium (Cs+) from clay minerals and soil. Most techniques use ion exchange with acids,...     

黄河下游地区河水主要离子和锶同位素的地球化学特征

对黄河下游地区河水主要阴阳离子、锶元素及其同位素组成进行了分析.结果发现其水化学组成主要以Ca~(2+),Na~+,HCO_3~-和SO_4~(2-)离子为主,分别占阴阳离子组成的75%以上.干流与支流间在化学组成上存在显著差异,黄河干流的SO_4~(2-),NO_3~-和Cl~-具有共同的来源,而支流河水中的SO_4~(2-),NO_3~-和Cl~-来源不同.黄河下游具有较高的锶含量及较低的锶同位素组成,锶含量变化范围在0.0429 mg·l~(-1)-0.936mg·l~(-1)之间,平均含量为0.394 mg·l~(-1),锶同位素组成变化范围在0.70986-0.71139之间,平均值为0.71118,其中黄河人海口的锶同位素组成(~(87)Sr/~(86)Sr=0.70986)与现代海水锶同位素比值(0.70916)相近,表明其锶同位素组成受海水作用影响较大.对主要元素、微量元素锶及其同位素组成分析研究发现,黄河下游地区河水锶同位素组成主要源于蒸发盐岩和碳酸盐岩的风化溶解作用,而人类活动的影响相对较小.由锶同位素平衡方程计算得出,黄河下游地区河水锶同位素组成由大气降水和岩石风化作用混合而成,其中大气降水对黄河下游地区~(87)Sr/~(86)Sr的贡献率约为30%,而岩石风化对其贡献率约为70%.     

饮水的化学组分与地氟病的关系

饮水的化学成分分析结果表明，徐州地区居民饮用水中的氟含量ｐＨ，Ｎａ＾＋，ＨＣＯ＾－３，Ａｓ，Ｂ和矿化度呈正相关关系，与Ｋ＾＋，Ｃａ＾２＋，Ａｌ＾３＋，Ｂａ＾２＋，Ｓｉ＾４＋呈负相关关系。地氟病的发病率不仅与饮水的氟含量密切相关，而且受饮水中其它组份的制榴，饮水中Ｃａ＾２＋，Ａｌ＾３＋，Ｓｒ＾２＋，Ｂ，Ｓｉ＾４＋，Ｋ＾＋，Ｇｅ＾４＋等组分的增高可抑制或减缓地氟病的发生。     

银铜离子复合体系的光催化还原

研究了在银、铜离子混合溶液中,TiO2／bead漂浮型光催化剂光催化还原银、铜的效果．考察了pH值、电子给体、络合剂以及反应气氛对银铜还原效率的影响．结果表明：银、铜离子的光催化还原与其电极电势以及在光催化剂表面的吸附有很大关系．pH值增大,银、铜离子在催化剂表面的吸附量增大,还原效率相应增大;电子给体、络合剂的加入以及无氧环境下对金属的还原有一定的促进作用．一般来说,银离子的光催化还原速率和程度比铜离子大．混合溶液中,银、铜离子的光催化还原具有协同作用。     

离子色谱法同时测定柠檬酸发酵液中无机阴离子和有机酸

本文建立了以ＮａＯＨ为淋洗液，甲醇为有机改进剂，阴离子交换分离，化学抑制型电导检测，快速测定柠檬酸发酵液中有机酸和ＳＯ＾２－４，ＰＬ＾３－４的离子色谱新方法，方法简单，灵敏，用于样品分析，结果令人满意。     

Comparative distributions of alkalies,alkaline earths and lead among major tissues of the tuna thunnus alalunga

The occurrences of K, Rb, Cs, Ca, Sr, Ba and Pb have been determined in various tissues of the tuna fish Thunnus alalunga. K, Rb, and Cs are distributed uniformly throughout the organs of the fish; 95% of the ca and Sr, and 70% of the Ba and Pb are contained in the skeleton. It is found that there are smaller amouts of Cs, Ba and Pb associated with the nutrient metals K and Ca in a marine animal compared to a terrestrial animal. This difference is a result of the purity of K and Ca in sea-water and the smaller amounts of trace metals associated with them compared to the impurity of K and Ca in terrestrial rocks. Food-chain enhancement and depletion of metals can be evaluated by comparing rations of trace metals to abundant nutrient metals in seawater and tuna. Cs is enriched relative to K in going from seawater to tuna by a factor of 13. Sr and Ba are both depleted by factors of 5 relative to Ca in going from seawater to tuna, while Pb is enriched relative to Ca by a factor of 14. Special clean laboratory procedures were used to prepare samples for accurate analysis by stable isotope dilution mass spectrometric techniques.Contribution No. 2640. Publications of the Division of Geological and Planetary Sciences, Californai Institute of Technology, Pasadena, California 91125, USA.