No abstract

A range of chloroplumbate(II) organic salts, based on the two cations, 1-ethyl-3-methylimidazolium and trihexyl(tetradecyl)phosphonium, was prepared by ionothermal synthesis. Depending on the structure of the organic cation and on the molar ratio of PbCl2 in the product, χPbCl2, the salts were room-temperature ionic liquids or crystalline organic/inorganic hybrid materials. The solids were studied using Raman spectroscopy; the crystal structure of [C2mim]{PbCl3} was determined and shown to contain 1D infinite chloroplumbate(II) strands formed by edge-sharing tetragonal pyramids of pentacoordinate (PbCl5) units. The liquids were analysed using (207)Pb NMR and Raman spectroscopies, as well as viscometry. Phase diagrams were constructed based on differential scanning calorimetry (DSC) measurements. Discrete anions: [PbCl4](2-) and [PbCl3](-), were detected in the liquid state. The trichloroplumbate(II) anion was shown to have a flexible structure due to the presence of a stereochemically-active lone pair. The relationship between the liquid phase anionic speciation and the structure of the corresponding crystalline products of ionothermal syntheses was discussed, and the data were compared with analogous tin(II) systems.

CO2foam is stabilized using by-product fly ash and recyclable iron oxide nanoparticles.

Cross-linked poly(acrylamide) microspheres, i.e. PAMBA, with mean diameters ranging from 169.7 to 525.2 nm were prepared by dispersion polymerisation of acrylamide in aqueous ammonium sulfate (AS) solution. N,N′-methylenebis(acrylamide) (MBA), sodium dodecyl sulfate (SDS), and potassium persulfate (KPS) were selected as the cross-linking agent, stabiliser, and initiator, respectively. The basic conditions for producing PAMBA microspheres, such as the salt concentration and monomer concentration, were optimised based on the precipitation behaviour of the polymer and the state of the product obtained after polymerisation. The optimum AS concentration and monomer concentration were determined as 300 and 88 g L−1, respectively. The effects of parameters, such as SDS concentration, MBA concentration, initiator concentration and temperature, on the product morphology and particle size were investigated by dynamic light scattering and transmission electron microscopy. The results show that the optimum conditions for the generation of microspheres are concentrations of 2.2–8.8 g L−1 for SDS, 4–6 g L−1 for MBA, 0.3–1.0 wt-% based on acrylamide for KPS, and the temperature should be kept at 35–45°C. The mean diameter of the microspheres decreases with an increase in SDS concentration and increases with an increase in MBA concentration. The polydispersity of the microspheres increases when SDS concentration exceeds 6.6 g L−1 as well as when MBA concentration increases. The formation mechanism of the products was discussed based on the results.