Water transport in aluminium oxide-poly(ethylene-co-butyl acrylate) nanocomposites

Polymer composites with metal oxide nanoparticles are emerging materials for use as insulation in electrical applications. However, the extensive interfacial surfaces and the presence of polar groups on the particle surfaces make these composites susceptible to water sorption. Water sorption kinetics were studied at 23 °C and different relative humidities (18–90%) for composites based on poly(ethylene-co-butyl acrylate) and aluminium oxide (?12 wt.%); the latter being in three different forms: uncoated and coated with either octyltriethoxysilane or aminopropyltriethoxysilane. The equilibrium water uptake increased linearly with increasing overall concentration of polar groups on the nanoparticle surfaces. Composites with well-dispersed nanoparticles showed Fickian diffusion (constant diffusivity and invariant boundary conditions) with a diffusivity that decreased with increasing filler content; the maximum factorial decrease in diffusivity was 300 with reference to that of the pristine polymer. This effect was most pronounced for composites with accessible polar groups on the particle surfaces, suggesting that water saturation of the composites is retarded by dual water sorption. Composites that contained a sizeable fraction of large nanoparticle agglomerates showed a two-stage sorption process: a rapid process associated with the saturation of the matrix phase and a slow diffusion process due to water sorption by the large nanoparticle agglomerates.     

Solid-vapor sorption of xylenes: prioritized selectivity as a means of separating all three isomers using a single substrate

A Werner complex is highly selective for o-xylene in a vapor mixture containing all three isomers. However, in the absence of o-xylene, the substrate shows similar selectivity for m-xylene over p-xylene. Kinetic studies show a different trend whereby m-xylene is absorbed most rapidly, implying that thermodynamic factors must be responsible for the selectivity.     

An excellent arsenic(V) sorption behavior of p-tert-butylcalix[8]areneoctamide impregnated resin

The present article describes the arsenic(V) extraction behavior of p-tert-butylcalix[8]areneoctamide (3) and of a resin (4) impregnated with 3. Liquid–liquid and solid–liquid (column sorption) extraction studies were carried out to optimize various experimental parameters such as pH, extraction effeciency and column stability. Thermodynamic studies based upon Temkin and Flory-Hugins models reveal that the sorption was spontaneous and exothermic. The values of correlation coefficients (R2) show that Langmuir and Freundlich isotherm models are best fit to describe the sorption equilibrium. Application of 4 to real samples indicates a slight decrease (5-7%) in extraction efficiency of 4 because of high concentration of total dissolved salts (TDS). It is deduced that 4 is highly effective for the removal of arsenic(V) at a wide range of pH and attains a maximum value, i.e. 99% at pH 4. The impregnated resin is easy to synthesize from cheap materials. It is more efficient and easily regenerable as compared to already reported resins.     

Flexibility and sorption selectivity in rigid metal-organic frameworks: the impact of ether-functionalised linkers

The functionalisation of well-known rigid metal-organic frameworks (namely, [Zn(4)O(bdc)(3)](n), MOF-5, IRMOF-1 and [Zn(2)(bdc)(2)(dabco)](n); bdc = 1,4-benzene dicarboxylate, dabco = diazabicyclo[2.2.2]octane) with additional alkyl ether groups of the type -O-(CH(2))(n)-O-CH(3) (n = 2-4) initiates unexpected structural flexibility, as well as high sorption selectivity towards CO(2) over N(2) and CH(4) in the porous materials. These novel materials respond to the presence/absence of guest molecules with structural transformations. We found that the chain length of the alkyl ether groups and the substitution pattern of the bdc-type linker have a major impact on structural flexibility and sorption selectivity. Remarkably, our results show that a high crystalline order of the activated material is not a prerequisite to achieve significant porosity and high sorption selectivity.     

氯化锶-膨胀石墨吸附制冰系统固化复合吸附剂性能

本文用质量分数占35%的膨胀石墨做添加剂并采用压块技术配置了氯化锶-膨胀石墨固化复合吸附剂,测试了该吸附剂在蒸发温度从-25～-5℃变化范围下的吸附制冷特性、吸附速率、最大吸附量以及最大转化率等相关参数,其中单位质量吸附剂最大吸附量可达0.7 kg/kg(NH_3/salt)。同时,通过计算分析,确定采用该复合吸附剂的吸附制冰系统平均SCP可达738 W/kg,COP可达0.435。     

A study of the partitioning and sorptive behaviour of butyltins in the aquatic environment

This study was designed to investigate the partitioning and sorptive behaviour of tributyltin(TBT), and its degradation products dibutylitin (DBT) and monobutyltin (MBT), in the aquatic environment. Factorial experiments were undertaken to determine the importance of pH and particulate matter concentration in the sorption of butyltin compounds to solid phases. Results indicate that in freshwaters MBT, and to a lesser extent TBT, will be partitioned towards the particulate phase, whereas DBT exhibits a 50:50 partitioning between particulate and solution phases. In estuarine waters, whilst MBT will almost exclusively sorb on to particulates, TBT will be predominantly in the solid-phase fractions but 10–30% may remain in solution. DBT, in contrast, is solubilized in estuarine waters. A more detailed investigation of TBT sorption and particulate matter concentration was undertaken using adsorption isotherms on different sediment types. The results from batch isotherm tests plotted according to the Freundlich adsorption model revealed that TBT adsorption varied with sediment type, increasing in the order sandy-silt < silty-sand < silty-clay. TBT sorption was found to be reversible, indicating that contaminated sediments may release TBT to overlying waters following sediment distrubance. Interstitial water partitioning studies indicate that TBT predominates in the particulate phase with partition coefficients for TBT higher than for DBT and MBT. The TBT partition coefficient in interstitial waters appears to be related to total organic carbon loadings.