Movement of Phosphamidon in Soil Columns

Abstract

Adsorption and movement of phosphamidon, a systemic non-ionic insecticide, was studied using two different types of Indian soil, clay loam and silt loam, of alluvial origin. Equilibrium adsorption coefficient, K, values determined by batch slurry technique were in the order: clay loam>silt loam. The distribution coefficient, K_d , for both soils in batch adsorption as well as in columns was also calculated. The phosphamidon movement measured in soil columns during water infiltration was in the order: silt loam > clay loam. This order was anticipated from the K and K_d values. A larger amount of water was needed for leaching the phosphamidon to 60 inches in clay loam than in silt loam soil.     

莠去津吸附的土壤淋溶柱色谱法研究

采用新发展的土壤淋溶柱色谱法,研究农药在水－土壤体系中的吸附。用土壤装填成液相色谱柱,以农药水溶液为流动相,以除草剂莠去津（２－氯－４－乙胺基－６－异丙胺基－ｓ－三嗪）为例,质量浓度从１９．７３μｇ／Ｌ至２９．６０ｍｇ／Ｌ,紫外检测器监测吸附平衡。吸附相中莠去津的质量浓度经甲醇淋洗液的测定值扣除柱内液相中的质量浓度后得到。对于极稀溶液,可采用在ＯＤＳ柱上富集－液相色谱台阶梯度法测定。莠去津在沙壤土上的吸附行为符合Ｆｒｅｕｎｄｌｉｃｈ方程式,其吸附常数Ｋｆ＝８４２．６ｍＬ／ｋｇ。     

Adsorption of some bivalent heavy metal ions from aqueous solutions by manganese nodule leached residues

The leached residue, generated after selective extraction of Cu, Ni, and Co in sulfur dioxide-ammonia leaching of manganese nodules, was characterized and batch isothermal adsorption experiments were conducted at ambient temperature to evaluate the effectiveness of the water-washed leached residue for removal of different bivalent metal ions from aqueous synthetic solutions. The effects of pH, initial metal ion concentrations, amount of adsorbent, interfering ions, and heat treatment were also investigated. The uptake of metal ions increased with increasing pH. Under identical conditions the adsorption capacity increased in the order Cd(2+)相似文献   

Mobilization and fractionation of137Cs in calcareous soils

Mobility of¹³⁷Cs was investigated in columns of calcareous loam and clay soils leached under river water, NH₄OAc, KCl, CaCl₂, and EDTA. Fractionation of Cs into ten sequential fractions was accomplished in the leached soils as well as in soil samples received carrier-free¹³⁷Cs and incubated for 60 d. At the end of 90 d of leaching with river water and CaCl₂, the bulk of Cs applied (>97%) was found to remain in the upper 1 cm of soil columns. On the other hand, the reduction in Cs concentration was approximately 30% with NH₄OAc, 18% with KCl, and 10 to 25% with EDTA. The major soil constituents appeared to be responsible for retaining Cs were clay, silt, and Fe oxides. The leaching consistently increased the magnitude of fractions bound to clay minerals and in most cases decreased the fractions of water soluble, exchangeable, carbonate, and organic matter.     

Sorption of the Pesticide Endosulphan on Two Indian Soils

Adsorption of endosulphan on uncontaminated sandy loam and silt clay loam soils in acetone-water and methanol-water mixtures at different f(s) values has been studied by the batch technique. Higher adsorption of endosulphan was observed on sandy loam soil than on silt clay loam soil, as was predicted from Freundlich constant K values and partition coefficient K(D) values. The K and K(D) values also confirm that adsorption of endosulphan was higher in acetone-water mixtures than in methanol-water mixtures and decreases with increases in the volume fraction of solvents (acetone, methanol), the f(s) values. The data were used to evaluate the cosolvent theory for describing adsorption of endosulphan in acetone-water and methanol-water mixtures. The aqueous phase partition coefficient K(DW) (mol/g) normalized on f(OC) (fraction of soil organic carbon) for endosulphan was evaluated by extrapolating to f(s)=0. Copyright 2000 Academic Press.     

Modeling Pb(II) adsorption onto sandy loam soil

The adsorption of Pb(II) onto hydrous sandy loam soil was investigated with batch equilibrium adsorption experiments. Results show that the amount of Pb(II) adsorbed increases with increasing pH and surface loading. It was demonstrated that the surface acidity of the soil could be determined using electrophoretic mobility measurements. The surface acidity constants, pK(a1)(int) and pK(a2)(int), were 1.57 and 3.43, respectively. A surface complex formation model (SCFM) was employed to describe the adsorption. The intrinsic stability constants, pK(i)(s), for the surface reaction between the Pb species and the ionized soil surface hydroxyl groups were determined from SCFM fitting. The adsorption free energy of Pb2+ and Pb(OH)+ ions ranges from -5.74 to -6.48 kcal/mol and from -9.68 to -10.00 kcal/mol, respectively, for surface loadings between 1.21 x 10(-5) and 2.41 x 10(-4) mol/g. The adsorption binding calculation indicated that the specific chemical interaction is the major mechanism responsible for the adsorption process.     

煤中溴的淋滤行为研究

在不同pH值条件下对来自重庆磨心坡矿煤样进行柱淋滤实验,用电感耦合等离子体质谱法( ICP-MS )测定煤中溴的含量及四种淋滤介质在不同时间段获取的淋出液中溴的浓度。结果表明,淋滤液的pH值、淋滤时间、煤中溴的赋存形态及在煤中赋存部位对溴的淋出有重要影响。淋滤液的酸性越强,煤中溴的最大淋出浓度越大,一定时间内溴的总淋出率也越高。 pH值为2的淋滤液,在淋滤前40h内淋出溴的量占总淋出量的80.65%;pH值为4的淋滤液,在淋滤前50h内淋出溴的量占总淋出量的89.42%。在酸性淋滤液作用下,首先被淋出的是存在煤颗粒表面的碳酸盐态和铁锰结合态溴,然后煤基质内部的水溶态和离子交换态溴才被淋出。柱淋滤实验表明,煤中溴在风化过程中,会被酸性雨水淋溶出来进入周围土壤或地表水体,造成周围环境溴的富集。     

Separation and Determination of Trace Amounts of Thallium by Nano-TiO2 Combined with Microwave Irradiation

Nano-TiO2 was employed for the separation and preconcentration of thallium.It was found that the adsorption ratio of thallium ions was more than 98% at pH 4.5 and the desorption ratio reached 99% under microwave irradiation for 3 min at 350 W.The adsorption equilibrium was well described by the Langmuir isotherm model with a maximum adsorption capacity of 4.09 mg/g[(20±0.1) °C].The nano-TiO2 was successfully applied to the determination of element thallium in the certified reference material polymetallic nodule and water samples.     

纳米TiO2对Ag(I)配合物的吸附

利用纳米TiO2的表面吸附活性, 以[S2O3]2-为络合剂, 应用火焰原子吸收光谱检测方法, 高效吸附分离了水中痕量Ag(Ⅰ). 系统研究了纳米TiO2的晶体结构、溶液的pH值、吸附时间、Ag(Ⅰ)的起始浓度及常见共存离子对吸附率的影响, 确定了最佳吸附条件. FTIR光谱分析结果表明, Ag(Ⅰ)配合物以物理作用吸附在纳米TiO2颗粒表面. 纳米TiO2对Ag(Ⅰ)的吸附等温线为S型, 表现出多分子层吸附特征. 硝酸和硫脲混合溶液可将吸附在TiO2纳米颗粒表面的Ag(Ⅰ)全部洗脱.     

Effect of biochar particle size on water retention and availability in a sandy loam soil

The ability of biochar to enhance the physical and hydrological properties of light textured soils is highly dependent on the characteristics of biochar including its particle size. To investigate the effect of biochar particle size on water characteristics and soil structure of a sandy loam soil, date palm biochar prepared at a pyrolysis temperature of 450–500 °C was fractioned by dry sieving into four sizes: 2–1, 1–0.5, 0.5–0.1, and <0.1 mm, and mixed in soil pots with a sandy loam soil at an application rate of 4%. The soil pots were incubated in a greenhouse for 120 days, and water content was kept at field capacity throughout the experiment. Water retention, hydraulic conductivity, and soil structure parameters were measured. Results showed that the largest increase in both water content at field capacity and available water content was observed with the smallest biochar particle size due to increased microporosity as a result to the larger internal surfaces and the porous structure of the biochar particles. Condense particle packing and increased tortuosity due to increased microporosity resulted in a reduction in saturated hydraulic conductivity and bulk density of the soil and biochar mixtures. Soil structure was improved in the soil and biochar mixtures at all biochar particle sizes, nevertheless, no significant increase in soil structures was observed among biochar particle sizes < 1 mm. The application of biochar with particle sizes < 1 mm can enhance the physical and hydrological properties of light textured soils and increase water conservation in the soil, which will help to reduce the amount of water required for irrigation. However, assessment under field conditions is required to assess the long-term effect of biochar on water characteristics and soil structure.     

超声波合成磁性4A沸石分子筛

为了解决微细粉末状沸石产品应用中与所处理溶液难以分离的问题, 在传统水热合成法合成4A沸石的晶化原料液中, 加入磁性Fe3O4微粒, 经过70 ℃, 功率为100 W的超声波晶化6 h, 合成了一系列Fe3O4含量不同的磁性4A沸石,并对其进行了XRD、SEM、IR、TG/DTA、EDX、磁化率及吸附性能等表征测试. 结果表明, 磁性4A沸石具有良好的磁稳定性, 其磁化率随Fe3O4含量的增加而增大; 磁性4A沸石对水中氟离子和六价铬的吸附与纯4A沸石性能相同, 其吸附速率可以用拟二级动力学方程来描述.     

掺杂MnO2土壤对多种雌激素化合物的吸附热力学特征及机理

通过析因实验设计优化了掺杂MnO2土壤对雌酮(E1)、雌二醇(E2)、17α-乙炔基雌二醇(EE2)、雌三醇(E3)和双酚A(BPA)等多种雌激素化合物的吸附条件,采用Langmuir吸附等温式和Gibbs方程考察了掺杂MnO2土壤吸附雌激素化合物的热力学规律和吸附过程的热力学性质,并利用傅里叶变换红外光谱对吸附机理进行了探讨,同时利用液相色谱-质谱联用技术对土壤中多种雌激素化合物的主要降解产物进行了定性分析.结果表明,雌激素化合物浓度和MnO2掺杂比例对雌激素化合物在掺杂MnO2土壤中的吸附量起显著的正效应,土壤质量对雌激素的吸附起负效应,土壤-水吸附体系的pH值对E2的吸附量起正效应而对E3起负效应.Langmuir吸附等温式能够描述雌激素在掺杂MnO2土壤中的热力学吸附行为(R2>0.99),吸附过程中雌激素化合物的ΔG均为负值,绝对值均小于40 kJ/mol,说明土壤吸附雌激素化合物为自发的物理吸附过程;掺杂MnO2土壤对雌激素的吸附既存在物理吸附作用,也存在化学降解作用.雌激素化合物的降解主要由于土壤中的有机碳增强了MnO2的导电性能,说明MnO2可以作为土壤固定化剂,能够有效地防止雌激素化合物因解吸作用而形成的"二次污染".     

以铜离子为模板的褐藻酸凝胶对铜离子的选择性富集研究

以铜离子为模板，制备了褐藻酸凝胶（Cu-alginate)，通过吸附实验及过柱渗滤实验，试验了该吸附剂对铜离子的选择性吸附性能，并且采用该吸附剂富集了自来水中微量的Cu^2 ，结合原子吸收法测定了水样中Cu^2 的含量。结果表明：该吸附剂对Cu^2 有较高的选择性吸附性能，显著优于一些化学合成铜离子模板缩聚物及非铜模板褐藻酸凝胶（如Ca-alginate),非重金属离子（如K^ 、Na^ 、Ca^2 ）及某些重金属离子（如Ni^2 、Cd^2 ）等对Cu^2 的吸附均不产生明显干扰。用该吸附剂富集水中的微量铜离子，回收率可达97.7%。     

活性炭负载磷钨酸催化剂的表征及其催化性能

研究了活性炭负载磷钨酸催化剂的表征及在丁基多苷合成中的催化性能.活性炭负载磷钨酸催化剂采用浸渍法制备,并用FT-IR光谱、XRD光谱、SEM等手段进行了表征.结果表明,磷钨酸负载到活性炭后保持了原有的Keggin结构,它在载体上的吸附过程可以分为单分子吸附、多分子吸附和体相堆积三个阶段.在丁基多苷合成反应中,催化剂负载量、磷钨酸溶脱量、葡萄糖转化率之间有较复杂的关系.杂多酸溶脱量随负载量增大而增大,转化率与杂多酸溶脱量之间没有直接联系.催化剂负载量在5%到60%之间变化时,控制催化活性的主要因素分别是催化剂酸量、比表面积、游离的杂多酸量.最佳负载量为20%.     

基于二级结构TiO_2纳米晶光阳极的高效染料敏化太阳能电池

本文报道了一种新型的二级结构TiO2纳米晶(nano-TiO2)光阳极的简单制备方法及其在高效染料敏化太阳能电池中的应用.通过添加适量TiCl4异丙醇溶液到传统nano-TiO2浆料中,可生成微米级nano-TiO2聚集体.该二级结构能有效提高光阳极光谱吸收和散射性能及电子传输和收集效率.基于这种结构光阳极的染料敏化太阳能电池光电性能有显著提高.在光阳极中将6μm厚传统nano-TiO2膜用相同厚度nano-TiO2聚集体替换,电池光电转换效率由5.03%提高到7.30%.进一步增加nano-TiO2聚集体的厚度能制备出更高光电转换效率的电池.     

膜吸附反应器（MAR）对饮用水系统中病毒的去除

以尺寸与人体肠道病毒相近的f2噬菌体作为模型病毒,本研究采用膜吸附反应器（Membrane adsorption reactor,MAR）,考察膜分离与纳米TiO2耦合工艺对饮用水中病毒的去除效果．两种不同孔径的PVDF（0．20μm）、PAN（0．05μm）平板膜在自来水体系中对f2噬菌体的截留效果分别为1．88～2．56log和4．78～5．95log,大大超过理论计算值,这与膜具有不规则孔型的重叠筛网状结构直接相关．吸附实验结果表明,纳米TiO2对f2噬菌体的吸附在60min内即可达到吸附平衡,符合Freundlich等温吸附模型qe=27．4·Ce1.24．两组MAR系统对f2噬菌体的总去除率分别高达3．88log与6．40log,这主要是由于纳米TiO2的吸附作用,以及运行中在膜表面形成有效的滤饼层．纳米材料与膜系统的耦合既保持了系统对病毒的高效去除,又实现了纳米颗粒的有效分离回收,操作简单、费用低．     

酸处理Silicalite—I沸石填充硅橡胶渗透蒸发分离膜

研究酸处理Ｓｉｌｉｃａｌｉｔｅ—Ｉ沸石对有机溶剂、水的吸附、脱附性质，酸处理Ｓｉｌｉｃａｌｉｔｅ—Ｉ填充硅橡胶膜对低浓度有机溶剂水溶液的渗透蒸发分离性能以及填充膜的力学性能。实验结果表明，在硅橡胶膜中填充酸处理Ｓｉｌｉｃａｌｉｔｅ—Ｉ沸石能改善膜对有机溶剂－水混合物的分离性能，且分离性能的改善与沸石在膜中的填充量以及硅橡胶的品种有关。另外，沸石的填充也有利于改善膜的力学性能。     

Simultaneous extraction and determination of fluoroquinolones,tetracyclines and sulfonamides antibiotics in soils using optimised solid phase extraction chromatography-tandem mass spectrometry

An analytical method was developed for the simultaneous extraction and determination of 18 fluoroquinolones (FQs), tetracyclines (TCs) and sulfonamides (SAs) antibiotics from soils using solid phase extraction and liquid chromatography-tandem mass spectrometry. The soils were extracted by different solvents with the help of mechanical shaking and ultrasonic treatment at 59?kHz, followed by a strong anion exchange (SAX) cartridge to clean up soil samples and a hydrophilic lipophilic balance (HLB) cartridge as enrichment. The method was evaluated by testing the following variables: extraction solvents, the type of SPE cartridges, solvent volumes, initial spiking levels and soil types (silty clay loam and clay loam soils). The soil extraction method was validated using these two types of soils, representing two typical agricultural soils in northern China. For 2?g soil, the extraction steps with the mixture of potassium phosphate buffer and acetonitrile (ACN) (1/1, v/v, pH 3.2) provided satisfactory recoveries. In the clay loam soil, the recoveries of all the compounds were from 56% to 89% at the spiking level of 50?µg?kg^?1 soil, and from 69% to 97% at the spiking level of 200?µg?kg^?1 soil, respectively. Recoveries in silty clay loam soil were similar to that in clay loam. The method was successfully employed using soil samples collected from a farmland and afforestion area irrigated with sewage in northern China. The result indicates that trace antibiotics in sewage may accumulate in soil irrigated by river water containing sewage.     

中国不同类型土壤中稀土元素的形态分布特征

采用中子活化分析地中国不同地带土壤中的稀土元素含量分布模型及其赋存形态进行了系统的研究。结果表明，黄棕壤，褐土，淋溶黑钙土及白浆土中稀土元素的分布均为轻稀土富集，Ｅｕ亏损型，砖红壤，红壤为轻稀土富集，Ｃｅ亏损型。     

动态法研究苯酚在饱水细砂土中的吸附

采用流动柱法研究苯酚在饱水细砂土中的吸附。实验结果表明，从开始到吸附量达一定数额这段区域内，总速率由界膜内的扩散速率决定，且为一常数。此后，总速率由颗粒外表层内的扩散速率决定，符合一级动力学微分方程。