A general model for the release of active agents incorporated in swellable polymeric matrices

A theoretical model, which takes proper account of the simultaneous uptake of a liquid leachant by a polymer matrix and the consequent release of a bioactive or other solute incorporated therein, is presented and the kinetics of release predicted under various conditions is investigated. This model is shown to be both more rigorous and much more widely applicable than previous attempts to approach the above problem. Furthermore, it can be easily modified or extended, in accordance with the information available about any particular system. It is, therefore, expected that the model introduced here will prove useful as a basis for the design of monolithic controlled-release devices of this type or for the evaluation of the leachability of low-level and medium-level radioactive wastes “immobilized” in polymeric matrices.     

己内酰胺基酸性低共熔剂对柴油的氧化脱硫:低共熔剂组成与催化反应活性（英文）

汽车尾气中硫化物的排放所导致的酸雨和PM2.5等环境污染问题广受关注.各个国家和地区也相继制定了严格的标准来控制柴油中的含硫量.加氢脱硫工艺成熟,但是需要在高温高压下进行,并且柴油中二苯并噻吩及其衍生物的位阻效应使得加氢脱硫难以将其脱除.氧化脱硫作为加氢脱硫的补充技术,以其反应条件温和等优点成为脱硫研究的重要课题.作为离子液体类似物,低共熔剂不仅具有离子液体的优点,而且无毒、生物可降解、价格低廉,且制备过程简单,是一种绿色溶剂.低共熔剂作为萃取剂和催化剂用于柴油的氧化脱硫中,展现出非常好的应用前景.尽管在低共熔剂氧化脱硫体系中氢键发挥着重要的作用,但是关于低共熔剂组成,氢键强度与氧化脱硫反应活性三者之间关系的探究相对缺乏.本文以己内酰胺和草酸为原料,调节二者配比制备了一系列己内酰胺基低共熔剂.通过差示扫描量热法、傅里叶变换红外光谱、核磁共振氢谱以及热重分析对制备的低共熔剂进行表征,从而确定组成与氢键之间的关系.将制备的低共熔剂应用于氧化脱硫体系中,发现氧化脱硫率随着低共熔剂组成的变化而规律变化.此外,系统地研究了影响氧化脱硫效率的反应参数.结果表明,在优化的反应条件下,己内酰胺基酸性低共熔剂的脱硫率可以达到98%.该反应体系下,三种不同硫化物的脱除率按照以下顺序依次递减:二苯并噻吩4,6-二甲基二苯并噻吩苯并噻吩.实验数据与表征结果表明,在低共熔剂氧化脱硫体系中氢键相互作用影响脱硫效率,而氢键相互作用则可以通过调节低共熔剂的组成来改变.该结果为了解柴油深度脱硫机理提供了新的思路.     

树脂酸性组分的氢氧化四甲铵甲基化与GC-MS分析

利用氢氧化四甲铵(TMAH)对马尾松树脂(塔罗油)进行甲基化，并对其产物进行GC—MS分析；研究表明TMAH甲基化后进行GC—MS分析是测定树脂中酸性组分的一种快速有效的方法，但酸性组分中的脂肪酸要比树脂酸难于甲基化，因此为了确保甲基化反应完全，应适当延长甲基化反应时间。     

酸性磷型萃取剂的结构与萃取钴,镍性能关系的研究

考察了一系列二烷基磷酸酯,烷基膦酸单烷基酯和二烷基膦酸对钴(Ⅱ)、镍(Ⅱ)的萃取性能。应用相关分析法探讨了萃取性能与萃取剂分子中取代基的极性效应和空间效应之间的关系。并依据萃合物立体构型的差异解释了萃取剂结构对萃取钴、镍的不同影响。     

Encapsulation of Water-Soluble Dye in Spherical Sol-Gel Silica Matrices

The water-soluble, Lithol rubine B, dye was encapsulated into silica microspheres matrices. Encapsulation has been carried out by sol-gel process of W/O microemulsions formed from sodium silicate and dye aqueous solution in cyclohexane medium. The average particle size could be tailored from 1–10 m, depending on the processing parameter such as homogenizing speed in the formation of W/O emulsion, the weight ratio of water to oil, and concentration of sodium silicate solution, etc. The pore size of dye-doped silica microspheres was measured by nitrogen adsorption-desorption isotherms. The leaching behavior of dye entrapped in silica matrices was investigated by UV/VIS and UV diffuse reflectance spectroscopy for the extract and solid powders after immersion for 24 h in water. The doping of GPTS (3-glycidoxypropyltrimethoxysilane) in sodium silicate and dye mixture solution greatly enhanced the stability against leaching of the dye. It was ascribed that GPTS serves simultaneously as an intermediate for the chemical bonding between the dye and silica, and as an agent for the formation of hybrid sol responsible for the shrinkage of pore size.     

REUSY-Ex的吸附性能及二次孔结构研究

应用高真空重量法(分别以苯和正庚烷为吸附质)和低温N2吸附法对REUSY-Ex的吸附性能和二次孔结构进行了研究.结果表明,在水热处理过程中可产生二次孔结构,且二次孔的形成与水热处理的脱铝深度相关.稀HCl浸取REUSY不仅能浸取出位于其二次孔中的非骨架铝(EFAL)碎片,而且还能浸取出位于微孔中的EFAL。29Si MAS NMR的结果显示,稀HCl浸取后,骨架Si(OAl)的谱宽变窄,裂分效果提高,表明其化学环境单一或均匀.     

超声辅助萃取-钨丝电热原子吸收光谱法测定痕量镉

镉对人体和动植物而言是一种非必需的元素,当其含量超过一定浓度就会产生毒性.由于镉在生物体内的半衰期长达1年之久,一旦进入生物体就不易排出.因此,测定食物样品中的镉对保证人类和动物的健康有重要的意义[1].     

银-邻菲罗啉-酸性三苯甲烷染料体系共振瑞利散射法测定痕量银

在磷酸盐缓冲介质中,PVA-124存在下,当银与邻菲罗啉(phen)形成配阳离子,并进一步分别与溴酚蓝(BPB)、溴甲酚绿(BCG)和溴甲酚紫(BCP)3种酸性三苯甲烷染料(TPMD)反应形成离子缔合物时,共振瑞利散射(RRS)强度急剧增强并产生相应的散射光谱。研究了离子缔合物的共振散射光谱特性以及适宜的反应条件。Ag+质量浓度在9.6×10-3~0.60μg/mL(BPB体系)、4.5×10-3~1.00μg/mL(BCG体系)和2.4×10-3~0.40μg/mL(BCP体系)范围内与RRS增强程度呈良好的线性关系。方法具有较高的灵敏度,不同染料体系的检出限在0.72~1.60 ng/mL。方法用于环境样品中痕量银的测定,结果满意。     

Selective extraction of U(VI), Th(IV), and La(III) from acidic matrix solutions and environmental samples using chemically modified Amberlite XAD-16 resin

A new grafted polymer has been developed by the chemical modification of Amberlite XAD-16 (AXAD-16) polymeric matrix with [(2-dihydroxyarsinoylphenylamino)methyl]phosphonic acid (AXAD-16-AsP). The modified polymer was characterized by a combination of ¹³C CPMAS and ³¹P solid-state NMR, Fourier transform-NIR-FIR-Raman spectroscopy, CHNPS elemental analysis, and thermogravimetric analysis (TGA). The distribution studies for the extraction of U(VI), Th(IV), and La(III) from acidic solutions were performed using an AXAD-16-AsP-packed chromatographic column. The influences of various physiochemical parameters on analyte recovery were optimized by both static and dynamic methods. Accordingly, even under high acidities (>4 M), good distribution ratio (D) values (10²–10⁴) were achieved for all the analytes. Metal ion desorption was effective using 1 mol L^–1 (NH₄)₂CO₃. From kinetic studies, a time duration of <15 min was sufficient for complete metal ion saturation of the resin phase. The maximum metal sorption capacities were found to be 0.25, 0.13, and 1.49 mmol g^–1 for U(VI); 0.47, 0.39, and 1.40 mmol g^–1 for Th(IV); and 1.44, 1.48, and 1.12 mmol g^–1 for La(III), in the presence of 2 mol L^–1 HNO₃, 2 mol L^–1 HCl, and under pH conditions, respectively. The analyte selectivity of the grafted polymer was tested in terms of interfering species tolerance studies. The system showed an enrichment factor of 365, 300, and 270 for U(VI), Th(IV), and La(III), and the limit of analyte detection was in the range of 18–23 ng mL^–1. The practical applicability of the polymer was tested with synthetic nuclear spent fuel and seawater mixtures, natural water, and geological samples. The RSD of the total analytical procedure was within 4.9%, thus confirming the reliability of the developed method.     

The adsorption of acidic gaseous pollutants on metal and nonmetallic surface studied by first-principles calculation: A review

Recent advances of SO₂, NO_x, H₂S and CO₂ adsorption on metal and nonmetallic surfaces by first-principles calculation are reviewed, and the common adsorption properties and calculation methods are summarized.