D296阴离子交换树脂分离富集原子吸收光谱法测定地质样品中的痕量金和钯

研究了D2 96 阴离子交换树脂对金、钯的吸附性能和解吸条件 ,用Z 80 0 0型原子吸收分光光度计在最佳条件下测定地质样品中的金和钯。试验表明 :溶液中的金和钯在 pH =1的盐酸介质中可以被D2 96 树脂吸附富集 ,并与其他贱金属分离。采用 0 .5mol·L- 1 的 3 %的酸性硫脲可以定量洗脱吸附于树脂上的金和钯 ,树脂结构不被破坏 ,可重新处理使用。洗脱液用火焰原子吸收法直接测定 ,并通过对比国家标准样品 ,其精确度令人满意。相对标准偏差 (n =6) :Au 3 .2 7% ;Pd 1 2 .2 2 %。检出限 :Au :2 .2 1× 1 0 - 8g·ml- 1 ,Pd :1 .0 6× 1 0 - 8g·ml- 1 。此法具有分离富集效率高、操作简便、节约试剂等优点 ,适用于地质样品中痕量金和钯的测定。     

A Direct GPC Calibration for Low Molecular Weight Polybutadiene,Employing Dual Detectors

Abstract

The calibration of gel permeation chromatograph (GPC) for a given polymer type is usually done by running well-characterized polymer samples of the same type. The available polystyrene and polyglycol standards with molecular weights below 5000 do not give parallel calibration curves, and the points for polystyrene are not on an extension of the higher-molecular-weight portion of the curve. In order to check the calibration in this low molecular-weight region and to establish an independent curve for polybutadiene, a polybutadiene sample prepared by a-methylstyrene tetramer-Na₂ initiation was chromatographed. In doing this, dual detection was used, consisting of a differential refractometer, and an ultraviolet absorption spectrophotometer.

The UV signal from the spectrophotometer was assumed to represent the tetramer portion of the polymer, and its percentage was calculated at each volume increment, using externally determined response factors. This percentage and the tetramer molecular weight gives the molecular weight of the polymer eluting at each volume increment. After correction for the aromatic portion of the polymer, these data and the points obtained with the polybutadiene standards were found to give a reasonable calibration curve for the entire range. The present paper describes the application of this technique to the examination of low molecular-weight polybutadiene.     

聚4-乙烯吡啶基碱性膜的制备及性能分析

采用自由基聚合制备聚4-乙烯吡啶(P4VP)。引入溴乙醇(BE)对制备的P4VP进行季铵化处理,合成一系列不同季铵化取代度的季铵化聚4-乙烯吡啶(QPVPE),最后,引入戊二醛(GA)与QPVPE进行交联,制备得到适合燃料电池使用的交联型聚4-乙烯吡啶基碱性膜。实验过程中,借助傅里叶变换红外光谱(FTIR)、紫外光谱(UV)、扫描电子显微镜(SEM)、热重分析(TGA,DTG)及力学性能测试等分析手段,对得到的导电膜结构及其理化性能进行分析,并对其导电性能进行性能测试。结果表明,QPVPE77.6%-GA16.87%膜综合性能最佳,该膜的电导率为10.48 mS/cm、含水率(WU)86.4%、溶胀率(SR)66.8%、拉伸强度为23.97 MPa。在25℃条件下,于1 mol/L的KOH溶液中浸泡192 h后,电导率损失为19%。因此,该膜具有较好的耐碱性能。     

Hydrogen and carbon dioxide adsorption with tetra‐n‐butyl ammonium semi‐clathrate hydrates for gas separations

Gas adsorption rates of H₂, CO₂, and H₂‐CO₂ gas mixture (H₂/CO₂ = 3.4) with tetra‐n‐butyl ammonium salt (bromide, chloride, and fluoride) semi‐clathrate hydrate particles were measured at 269 K to assess their properties for gas separation. Equilibrium gas occupancies in the S‐cages of the particles were in order of (high to low) for hexagonal structure‐I, tetragonal structure‐I, and superlattice of cubic structure‐I structures with the maximum fractional occupancy by CO₂ being about 40%. The CO₂ diffusion rate depended on the anion size of the salt, which is attributed to distortion of the S‐cage that is close to the molecular size of CO₂. Simulations of semi‐clathrate hydrate particles with theory showed that H₂/CO₂ selectivities could be as high as 36 (3.0 mol% TBAF) and that selectivities for an ideal membrane (3.3 mol% TBAF) could be >100 (269 K, 0.3–4.5 MPa). Semi‐clathrate hydrates have wide application as separation media for gas mixtures. © 2014 American Institute of Chemical Engineers AIChE J, 61: 992–1003, 2015     

山西某贫磁铁矿精矿提质试验研究

山西某磁铁矿矿物嵌布粒度微细,属极贫难选磁铁矿石,以其为原料的某选厂采用阶段磨矿．单一磁选工艺,生产指标较低,不能满足市场需求。针对该矿石进行提质试验研究,确定了合理的工艺流程,即阶段磨矿．磁精再磨．阴离子反浮选工艺,最终使精矿品位由55％提高到65％以上,有效地提高了产品质量和市场竞争力,为选矿工艺改造提供了技术依据,促进了该矿石的合理利用。     

D290大孔阴离子交换树脂吸附钽的性能及动力学研究

研究了D290大孔阴离子交换树脂从草酸水溶液中吸附钽草酸配合物的性能和动力学。实验结果表明，在[（NH4）2C2O4]＝0．13mol／L、[K2S2O7]＝0．03mol／L、[Ta]＝8×10－5mol／L，pH＝1．0条件下，钽的吸附率有最大值。测得Freundlish常数K＝11．59，吸附速率常数k25℃＝1．5×10－4s－1，吸附活化能Ea＝46．64kJ／mol，钽的饱和吸附容量为每克干树脂170．4mg。载钽饱和柱可用6mol／L硫酸洗脱，洗脱率可达98．92％。     

两种选别齐大山铁矿石工艺流程的研究应用

目前选别齐大山铁矿石的工艺流程分别为“阶段磨矿、重-磁-阴离子反浮选”和“连续磨矿、弱磁-强磁-阴离子反浮选”。介绍了两个工艺流程研究过程，分析了其特点，并进行了评述。     

The correlation between the ionic degree of covalent bond comprising polymer main chain and the ionic yield due to mechanical fracture

The mechanical force to polymeric materials in vacuum at 77 K produces mechano radicals, mechano anions and mechano cations due to homogeneous and heterogeneous scissions of the covalent bonds comprising polymer main chain. The ionic degree of the covalent bond was estimated by calculating the “absolute ΔMulliken atomic charge,” which was defined as the difference between the Mulliken atomic charges of the two adjacent atoms comprising the covalent bond of the polymer main chain. The ionic yield of the covalent bond increased with increasing the absolute ΔMulliken atomic charge. The empirical formula for the ionic yield was obtained with the absolute ΔMulliken atomic charge, and indicates that the ionic yield could be estimated from its chemical structure.     

Atom transfer radical polymerization (ATRP): A versatile and forceful tool for functional membranes

The progress in atom transfer radical polymerization (ATRP) provides an effective means for the design and preparation of functional membranes. Polymeric membranes with different macromolecular architectures applied in fuel cells, including block and graft copolymers are conveniently prepared via ATRP. Moreover, ATRP has also been widely used to introduce functionality onto the membrane surface to enhance its use in specific applications, such as antifouling, stimuli-responsive, adsorption function and pervaporation. In this review, the recent design and synthesis of advanced functional membranes via the ATRP technique are discussed in detail and their especial advantages are highlighted by selected examples extract the principles for preparation or modification of membranes using the ATRP methodology.