A Comparative Study of the Hydroxyl Value and Iodine Value in Polyoxyl Stearyl Ether in United States Pharmacopeia Specifications

The iodine value (iodine number) and hydroxyl value are important analytical characteristics of fats and oils. The iodine (I2) required saturating the fatty acids present in 100 grams of the oil or fat. Iodine value is a measure of the total number of double bonds (-C=C-) present in fats and oils. Unsaturated compounds contain molecules with double and triple bonds which are very reactive towards iodine. The iodine value has been determined according to Hanus with iodine monobromide in glacial acetic acid, and then the amount of iodine remaining unreacted is determined by titration using sodium thiosulfate volumetric standard solution. The hydroxyl value is the amount of potassium hydroxide in milligrams that is equivalent to the hydroxyl amount of 1 gram of the sample (mg KOH/g sample). Poloxyl Stearyl Ether is a mixture of the monostearyl ethers of mixed polyethylene glycols. It may contain various amounts of free stearyl alcohol and some free polyethylene glycol. In this study, the iodine value and hydroxyl value have been determined by titration in polyoxyl stearyl ether. Iodine value 1.84 g of I2 absorbed/100g sample, and hydroxyl value 162.65 mg KOH/g sample have been found in poloxyl stearyl ether. The iodine value and hydroxyl value results met the United States Pharmacopeia specifications for Polyoxyl Stearyl Ether.

Syntheses and Adsorption Property Research of N-Diethyl Imidazole Modified PS Resins for Iodine

A new N-diethyl imidazole modified PS resins was synthesized in this paper. The composition, structure, and properties of the resulting resins were studied by means of Fourier transform infrared (FTIR) and elemental analysis methods. The results showed that the resins hold the adsorption function group of quaternary ammonium structure. Meanwhile, the adsorption properties of the resulting resins for iodine were investigated. The results showed that the uptake of iodine found to be higher at natural water than at acidic medium;the adsorption capacity increased with the increasing of temperature, but when the temperature is higher than 30°C, adsorption capacity didn’t increase;the adsorption kinetics of the resins can be modeled by pseudo first-order rate equation and pseudo second-order rate equation wonderfully;Both Freundlich equations and Langmuir equations could well interpret the adsorption of resins for iodine.

Iodine Sorption Value and Surface Chemical Analysis of Regenerated Cellulosic Fibres

The surface chemical analysis and bulk analysis were conducted for fibres regenerated from waste garments and treated with iodine solution. The aim was to assess the fibre accessibility by the iodine solution and ascertain the location of the reagent within the fibres. X-ray Photoelectron Spectroscopy (XPS) analysis indicated that the fibres regenerated from indigo dyed waste denim garments (ReCell-Denim) had a relatively high accessibility by the iodine solution compared to the standard lyocell, ReCell-1 and ReCell-2 fibres. With the exception of ReCell-Denim, the standard lyocell, ReCell-1 and ReCell-2 fibre’s iodine sorption values correlated well with the percentage crystallinity. The high accessibility of the ReCell-Denim fibres was attributed to the presence of the positively charged nitrogen from the indigo dyes that improved the substantivity of the fibres to the iodine solution. The iodine sorption of the fibres is relatively higher in the bulk compared to the fibre surface.

Adsorption of gaseous iodine-131 at high temperatures by silver impregnated alumina

To prevent radioactive iodides from releasing into the environment in an accident of a nuclear power plant,silver-impregnated alumina(Ag/Al2O3)was fabricated,and its performance of radioactive iodine adsorption from high-temperature gas was tested.The silver loadings on alumina were obtained by ICP-OES and the texture properties of Ag/Al2O3were characterized by N2adsorption-desorption.The Ag/Al2O3was of reduced specific surface(107.2 m2/g at 650?C).Crystalline phases of Ag/Al2O3were confirmed through XRD characterization.After calcination at 650?C for 2 h,the crystalline phase of Ag/Al2O3changed.The131I-removal efficiency of Ag/Al2O3was tested at 100,250,350,450 and 650?C,with good decontamination factor values for the radioactive iodine.Silver-impregnated alumina can be applied as adsorbents to remove radioactive iodine at high temperatures in nuclear accident.

Acute Toxicities of Potassium Permanganate, Formalin, and Lugol's Iodine Solution to a Marine Ciliate, Pleuronema coronatum (Ciliophora, Scuticociliatida)

Acute toxicities of potassium permanganate, formalin, and Lugol’s iodine solution to a commonly occurred marine ciliate Pleuronema coronatum (Ciliophora, Scuticociliatida) were measured. Linear regression analysis of the results highlighted the close relationships between doses of the medicines and mortalities of the organisms, thus providing a capability to predict toxicity effects from the dose. Toxic effects of the medicines on the ciliates were described in the present paper, and the median lethal concentrations (LC 50 values) were given. Results of measurements indicated that 2 h-LC 50 and 12 h-LC 50 values of formalin on P. coronatum were 59.00×10 -6 and 43.57×10 -6, while those of Lugol’s solutions were 90.13 and 67.84×10 -6 respectively. The tolerance of P. coronatum to formalin is apparently lower than that to Lugol’s iodine solution and potassium permanganate is a suitable medicine to kill ciliates in short time.

A tetraaldehyde-derived porous organic cage and covalent organic frameworks:Syntheses,structures,and iodine vapor capture

Dynamic covalent imine reactions between 2,3-dimethoxy-[1,1:4,1-terphenyl]-3,3,5,5-tetracarbaldehyde(DMTT)and cyclohexanediamine,p-phenylenediamine,and benzidine,respectively,generate a porous organic cage(DMPOC)and two covalent organic frameworks(COFs),USTB-29,and USTB-30.DMPOC shows a[3+6]topological cage-like structure according to single crystal X-ray diffraction result.In contrast,both microcrystalline USTB-29 and USTB-30 exhibit two-dimensional monoporous structures in an eclipsed AA stacking style based on powder X-ray diffraction and theoretical simulations.In addition,DMPOC is capable of efficiently absorbing the iodine vapor with an outstanding uptake of 5.10 g/g,much higher than that of USTB-29(3.07 g/g)and USTB-30(3.16 g/g).Cage to COFs transformations have been realized from DMPOC to USTB-29 and USTB-30 via the imine bond exchange with slightly increased iodine vapor uptake.Mechanism investigations uncover that both nitrogen and oxygen atoms of POC and COFs contribute to iodine vapor capture due to the formation of charge transfer matter,and loose interaction introducing adaptive expanding voids of DMPOC is suggested to capture more iodine vapor than that of COFs with strongπ-πinteractions.

Optimizing iodine capture performance by metal-organic framework containing with bipyridine units

Radioactive iodine exhibits medical values in radiology,but its excessive emissions can cause environmental pollution.Thus,the capture of radioiodine poses significant engineering for the environment and medical radiology.The adsorptive capture of radioactive iodine by metal-organic frameworks(MOFs)has risen to prominence.In this work,a Th-based MOF(denoted as Th-BPYDC)was structurally designed and synthesized,consisting of[Th_(6)(μ_(3)-O)_(4)(μ_(3)-OH)_(4)(H_(2)O)6]^(12+)clusters,abundant bipyridine units,and large cavities that allowed guest molecules diffusion and transmission.Th-BPYDC exhibited the uptake capacities of 2.23 g·g^(-1) and 312.18 mg·g^(-1) towards I_(2) vapor and I_(2) dissolved in cyclohexane,respectively,surpassing its corresponding analogue Th-UiO-67.The bipyridine units boosted the adsorption performance,and Th-BPYDC showed good reusability with high stability.Our work thus opened a new way for the synthesis of MOFs to capture radioactive iodine.

Adsorption Kinetics of NH_4^+ by Purple Soils with Different pH Values

Ammonium adsorption and desorption properties by purple soils with dif- ferent pH were studied. The results showed that the adsorption and desorption amounts of NH4＋ by purple soils increased with the increase of NH4＋ concentration, regardless of soil pH values; the largest adsorption and desorption amounts of NH4＋ by purple soil at pH 6.0 were 10.3 and 7.96 mg/g, respectively; the largest adsorp- tion and desorption amounts of NH4＋ by purple soil at pH 7.2 were 12.8 and 4.62 mg/g, respectively; the largest adsorption and desorption amounts of NH4＋ by purple soil at pH 8.0 were 13.5 and 2.23 mg/g, respectively. The isothermal adsorption ki- netics of NH4＋ by purple soils fits the Freundlich equation best （R〉0.95）. This study shows that the adsorption of NH4＋ by purple soils with different pH values is multi- molecular layer uneven surface adsorption.

Thiophene-based covalent organic frameworks for highly efficient iodine capture

Development of adsorbent materials for highly efficient iodine capture is high demand from the perspective of ecological environment and human health. Herein, the two kinds of thiophene-based covalent organic frameworks(COFs) with different morphologies were synthesized by solvothermal reaction using thieno[3,2-b]thiophene-2,5-dicarbaldehyde(TT) as the aldehyde monomer and tri(4-aminophenyl)benzene(PB) or tris(4-aminophenyl)amine(PA) as the amino monomer(denoted as PB-TT COF and PA-TT COF) and the as-prepared two heteroatoms-rich COFs possessed many excellent properties,including high thermal stability and abundant binding sites. Among them, PB-TT COF exhibited ultra-high iodine uptake up to 5.97 g/g in vapor, surpassing most of adsorbents previously reported, which was ascribed to its high specific surface(1305.3 m2/g). Interestingly, PA-TT COF with low specific surface(48.6m2/g) showed good adsorption ability for iodine in cyclohexane solution with uptake value of 750 mg/g,which was 2.38 times higher than that obtained with PB-TT COF due to its unique sheet-like morphology.Besides, the two COFs possessed good reusability, high selectivity and iodine retention ability. Based on experimental results, the adsorption mechanisms of both COFs were studied, revealing that iodine was captured by the physical-chemical adsorption. Furthermore, the both COFs showed excellent adsorption ability in real radioactive seawater treated safely, demonstrating their great potential in real environment.

Efficient capture of iodine and methyl iodide using all-silica EMM-17 zeolite

Hydrophobic zeolites have been identified as suitable adsorbents for capturing radioactive iodine species from nuclear-powerplant off-gas because of their high stability and strong water resistance.However,only the most common zeolites have been investigated for the capture of molecular iodine to date.Herein,we demonstrate that the composition and pore structure of zeolites considerably affect their iodine adsorption performance.A novel all-silica ExxonMobil material-17(EMM-17)zeolite having a unique three-dimensional 10(12)×10(12)×11-ring channel system exhibits a high adsorption capacity for iodine and methyl iodide in the presence of water.EMM-17 outperforms previously reported zeolites in terms of gravimetric and volumetric adsorption capacity in dynamic adsorption measurements.The excellent iodine/methyl iodide capture properties are attributed to the combination of optimal pore size,high pore volume,strong hydrophobicity,suitable particle morphology.This study provides useful insights for designing efficient adsorbents for iodine capture.

Iodine Adsorption Studies of Dipalladium-based Supramolecular Cages

Four water-soluble cage-like hosts(1·4NO3^(-)_(2):{[(bpy)_(2)Pd_(2)]_(2)L^(1)_(2)}(NO_(3))_(4),2·4NO3^(-)_(2):{[(bpy)_(2)Pd_(2)]_(2)L^(2)_(2)}(NO_(3))_(4),3·6NO3^(-)_(2):{[(bpy)_(2)Pd_(2)]_(3)L^(3)_(2)}(NO_(3))_(6)and 4·6NO3^(-)_(2):{[(bpy)_(2)Pd_(2)]_(3)L^(4)_(2)}(NO_(3))_(6)have been successfully self-assembled by coordinating the flexible amide based polypyrazole ligands(H_(2)L^(1):N^(1),N^(4)-di(lH-pyrazol-5-yl)terephthalamide,H_(2)L^(2):N^(1),N^(4)-bis(3-methyl-1H-pyrazol-5-yl)-terephthalamide,H_(3)L^(4):N^(1),N^(3),N^(5)-tri(1H-pyrazol-5-yl)benzene-1,3,5-tricarboxamide and H^(3)L^(4):N^(1),N^(3),N^(5)-tris(3-methyl-lH-pyrazol-5-yl)benzene-1,3,5-tricarboxamide)with dipalladium comers([(bpy)_(2)Pd_(2)(N0_(3))_(2)](N0_(3))_(2),where bpy=2,2'-bipyridine)in aqueous solution.Their structures were characterized by^(1)H NMR,ESI-MS and single-crystal X-ray diffraction.Notably,all the four supramolecular assemblies are capable of adsorbing iodine molecules via halogen bonds and other supramolecular interactions.

A Two-dimensional Covalent Organic Framework for Iodine Adsorption

Radioactive iodine is a notorious pollutant in gas radioactive nuclear waste due to its radiation hazard, volatility, chemical toxicity, and high mobility. Therefore, developing a material with high efficiency-specific iodine capture is significant. Covalent organic framework(COF) has attracted significant attention as a new crystalline porous organic material. Due to its large specific surface and high chemical stability, it is an excellent alternative to adsorbents. Herein, we report a chemically stable two-dimensional COF(termed JUC-609) with specific adsorption of iodine. Adsorption experiments show that JUC-609 has an excellent iodine adsorption capacity as high as 5.9 g/g under 353 K and normal pressure condition, and iodine adsorption after multiple cycles is still maintained. Our study thus promotes the potential application of COFs in the field of environment-related applications.

A Simple Colorimetric Procedure for the Determination of Iodine Value of Vegetable Oils Using a Smartphone Camera

A smartphone camera-based colorimetric method is developed for the determination of iodine value of vegetable oils.The small amount of Wijs reagent is employed for halogenation of the unsaturated sites of the sample.The rest of unreacted reagent is transformed into iodine,which further reacts with the starch solution to form the blue color complex.The free download smartphone application is used for measuring the blue color intensity.More than one sample can be measured by taking only one photo shot.Under the controlled illuminance,the calibration graph for measuring the iodine values of various vegetable oils is constructed from the dissolved triiodide.The detection and quantitation limits are less than 0.02 and 0.032 mM I;,respectively.This method provides a better determination result of the iodine value compared with the standard titrimetric method.This method is convenient,simple,rapid,inexpensive,and easy operation with few chemical waste products.

A cationic nanotubular metal-organic framework for the removal of Cr_(2)O_(7)^(2-) and iodine

In this work,two new metal-organic frameworks(MOFs)based on a pyrazole-imidazole heterotopic ligand,namely,SCNU-Z8(Co)and SCNU-Z8(Ni),are constructed.They are isostructural,and the crystal structure of SCNU-Z8(Co)is further analyzed by single-crystal X-ray diffraction.They are 3D cationic frameworks with 1D tubular channels and possess a highly(3,9)-connected binodal gfy network topology.SCNU-Z8(Ni)can be syn-thesized in high yield with high phase purity;thus,it is selected to be further explored.A stability study shows that its framework is stable in water at different pH values and in many organic solvents.It can be applied to capture Cr_(2)O_(7)^(2-)anions in water with a moderate adsorption capacity of 130 mg/g via anion-exchanged process.Iodine molecules in vapour phase and cyclohexane solution can also be captured by SCNU-Z8(Ni).In the case of iodine vapours and iodine cyclohexane solution,the adsorption capacity reaches up to 4.1 g/g and 640 mg/g,respectively,which are among the best in MOFs.Most of the absorbed iodine molecules are stably captured in the framework and hard to release,which may be conducive to allow the permanent storage of radioactive iodine.

Correlation Evaluation of Ion Adsorption-Based Rare Earth Leaching Performance Based on Zeta Potential Drop Leaching

Rare earth elements are indispensable raw materials for advanced aero-engines, special optical materials, and high-performance electronic products. With the development of the social economy, the global demand for rare earth resources is increasing, and rare earths have become a key metal for the development of new industries and frontier technologies that are highly valued both at home and abroad. Ion-adsorbed rare earth ores are an important source of rare earths, so the efficient green leaching of ion-adsorbed rare earths is important. Researchers found that the selection of an efficient green leaching agent for ion-adsorbed rare earths is based on the zeta potential of tailing clay minerals in addition to leaching efficiency, and both zeta potential and leaching ion concentration are related to mineral acidity and alkalinity, and the pH of tailing water suspension is a direct indicator of environmental water quality requirements. Therefore, the efficiency of the leaching process is closely integrated with the environmental evaluation, and the characteristics and correlation of the changes in zeta potential, pH, conductivity and pollutant concentration of the pulp of clay mineral content during the leaching process of ore leaching and tailings aqueous electrolyte solution leaching are studied by evaluating the leaching system, and a set of correlation leaching efficiency and environmental impact evaluation method is established based on the results of the above analysis, which is of scientific development of ion adsorption rare earth resources. It has important theoretical significance and practical application value.

氧化铋负载聚丙烯腈复合球体对溶液中碘的吸附性能研究

采用水热法和相转移法合成了易于实现固液分离的氧化铋负载聚丙烯腈复合球体,将其用于溶液中碘离子的吸附性能研究,详细探讨了氧化铋和聚丙烯腈的物质的量比、体系酸度、碘离子初始浓度等因素对碘离子吸附性能的影响。结果表明,当氧化铋和聚丙烯腈的物质的量比为2∶1时,合成的吸附剂吸附效果最佳,溶液pH为7.0时,吸附剂对碘离子的吸附在210 min可达吸附平衡,最大实验吸附容量为122.3 mg/g。Langmuir和准二级动力学模型可以较好地拟合该吸附过程,Langmuir拟合计算得到的理论吸附容量为135.7 mg/g,动力学拟合表明该吸附以化学过程为主,颗粒内扩散会对吸附速率产生较大影响。采用氯化钾溶液可以洗脱被吸附的碘离子,吸附洗脱实验结果表明氧化铋负载聚丙烯腈复合球体的重复使用性良好。

基于超声改性橡胶籽壳活性炭的制备方法研究

以农业废弃物橡胶籽壳为原料,以KOH为活化剂,与超声处理相结合制备活性炭,通过调整制备处理条件对活性炭的表面结构进行调控,以获得最佳制备条件。采用傅里叶显微红外、扫描电镜、元素分析、热重分析等手段,研究活性炭的物理化学特性,考察其吸附能力,并比较超声预处理与未超声预处理的活性炭的特性。研究得出最优制备条件为:剂料比为1∶1,超声作用时间为60 min,活化时间为60 min,活化温度为700℃。超声预处理后的活性炭(UAC)的亚甲基蓝吸附值为400 mg/g、碘吸附值为1340.2 mg/g、得率达25.9%,总孔容为0.9511 cm^(3)/g,比表面积为1034.5009 m^(2)/g;未经超声预处理的活性炭(NAC)的亚甲基蓝吸附值为300 mg/g,碘吸附值为894.0 mg/g,得率为20.8%,比表面积为690.2461 m^(2)/g,总孔容为0.6830 cm^(3)/g。二者均含羟基、醇羟基、羰基官能团,橡胶籽壳活性炭的氮气吸附等温线为Ⅰ型。KOH活化后的活性炭表面存有大量孔结构,UAC活性炭表面光滑平整,有许多丰富规则的孔结构,优于NAC活性炭。橡胶籽壳的碳(C)含量丰富,经过KOH活化后,UAC和NAC的C含量由原来的56.81%,分别提高到75.97%、64.89%。KOH活化后的样品比橡胶籽壳更加稳定,UAC和NAC样品的总重量分别损失62%和68%之后趋于稳定。综上所述,超声处理制备的活性炭性能更佳,说明超声波的空化效应作用在活性炭结构表面,使其结构发生变化,进而提高其吸附性能、比表面积等。

椭圆型碘吸附器设计与性能分析

为满足受限空间或小风量核设施通风系统对碘吸附器的需要,设计了一种椭圆结构的碘吸附器。针对该碘吸附器进行了内部流场模拟分析和整机性能测试。试验结果表明:碘吸附器内部气流分布均匀,结构设计合理,体积小、重量轻、与系统连接方便快捷,在300 m^(3)/h流量下阻力小于300 Pa,机械泄漏率小于0.01%,放射性甲基碘吸附效率大于99.99%,总体满足核设施通风系统中碘吸附器放射性碘的净化处理需求,并实现了工程应用。

四苯基甲烷共价有机框架材料对气态碘的吸附

为获得高效稳定的气态碘吸附材料,以四苯基甲烷作为醛基单体,分别与4,4’-二氨基三联苯和2,6-二氨基蒽在水热条件下合成了共价有机框架材料(COFs)DpTp-COF和AnTp-COF,合成的材料能够在400℃保持结构稳定,DpTp-COF和AnTp-COF的比表面积分别达到了955 m^(2)/g和786 m^(2)/g。实验条件下DpTp-COF和AnTp-COF对气态碘的最大吸附容量分别为4.75 g/g和4.95 g/g,吸附过程符合准二级动力学方程。吸附碘的COFs材料可以用乙醇实现碘的脱附,经过四次吸附-脱附循环后DpTp-COF和AnTp-COF的最大吸附容量分别降低了19.36%和24.85%。对吸附碘的DpTp-COF和AnTp-COF进行拉曼光谱和X射线光电子能谱表征,发现碘主要以I_(3)^(-)和I_(5)^(-)形式存在于两种材料上,表明COFs材料和碘分子之间发生了电荷转移。

金属有机框架复合材料对放射性碘的吸附机制研究进展

【目的】以金属有机框架(metal-organic framework,MOF)复合材料作为吸附剂高效吸附核电站运行、核燃料后处理、核医学过程以及核事故等所泄漏的放射性碘,研究MOF复合材料对放射性碘的吸附机制,消除环境中的放射性碘污染。【研究现状】综述了近年来MOF复合材料吸附放射性碘的基于化学反应、强化MOF空间结构和电子转移的吸附机制。MOF中掺杂银、铜和铋金属或金属氧化物生成的MOF复合材料具有较大的接触面积和较多的活性位点,铋掺杂MOF复合材料对气态I_(2)的吸附性能最优。在MOF复合材料中掺杂多孔材料能增大孔隙体积;高温热解MOF复合材料使得活性位点均匀分布并提高利用率;在MOF复合材料中嵌合纳米复合膜或离子液体能够与吸附物充分接触,回收性和重复利用性好;改变MOF的金属节点或共轭同类MOF衍生出的MOF复合材料,可增强对放射性碘的物理吸附性能。MOF复合材料可以经过碳化作用增强与放射性碘的电荷转移作用,I_(2)能以络合物的形式吸附在MOF复合材料的活性位点上。【结论与展望】虽然对MOF复合材料对放射性碘的吸附机制的研究取得重要进展,但仍然面临着吸附容量小、吸附速率慢、回收利用性差及活性位点利用率低等问题。提出应进一步研究铋掺杂MOF复合材料,探究在高温条件下对放射性碘的吸附机制,采取适当措施减少金属掺杂MOF复合材料对环境的二次污染。