silicon and ferrous-chloride

Polyelectrolyte complexes (PECs)/polyvinyl alcohol (PVA) membranes are prepared from PVA, anion exchange and cation exchange multisilicon copolymers, which contain plenty of functional groups of OH, N(+)(CH3)3/Si(OCH3)3, and SO3Na/Si(OCH3)3, respectively. The OH and Si(OCH3)3 groups can undertake sol-gel reaction to form crosslinking structure, while the N(+)(CH3)3 and SO3Na groups can be combined through electrostatic interaction. The PECs/PVA membranes exhibit improved thermal stability, swelling resistance and flexibility as compared with single anion or cation exchange hybrid membranes. The PECs/PVA membranes have the water uptakes (WR) of 25.3-70.4%, initial decomposition temperatures (IDTs) of 246-285°C, tensile strength of 23.1-33.8 MPa, and elongation at break of 3.5-13.1%. The membranes can be potentially applied for both acid and alkali recovery through diffusion dialysis (DD) process. The separation factor (S) for HCl/FeCl2 mixture can reach up to 89.9, which is about five times higher than that of commercial DF-120 membrane (18.5 at 25°C). The dialysis coefficients of NaOH (UOH) are in the range of 0.014-0.019 m/h, around 7-9 times higher than the value of commercial SPPO membrane (0.002 m/h at 25°C). The membranes also show potential usefulness for industrial acidic and alkali wastes treatment.

Topics: Dialysis; Diffusion; Ferrous Compounds; Hydrochloric Acid; Ion Exchange; Membranes, Artificial; Polyvinyl Alcohol; Silicon; Sodium Hydroxide; Tungsten Compounds

Desorption/ionization on porous silicon (DIOS) is a very useful technique in the case of small molecular weight compounds, compared to the matrix-assisted laser desorption ionization (MALDI). This is because MALDI generates matrix-related ions that overlap with the mass range of interest. The aim of our work was to investigate the suitability of the DIOS technique in the case of fatty acids in negative ion mode. The analysis of the chosen fatty acid models, nonadecanoic acid (C(19)H(38)O(2)) and heneicosanoic acid (C(21)H(42)O(2)), gave rise to the observation of the deprotonated monomeric species and selective cationized multimeric species. This cation selectivity was further elucidated by complementary studies based on the addition of various metals such as Ag(I), Zn(II), Fe(II), and also Cu(II). Specific behavior, depending upon the introduced metal, was highlighted by different redox reaction processes and also metastable decompositions (in PSD mode).

Topics: Acetates; Cations; Chlorides; Copper; Dimerization; Fatty Acids; Ferrous Compounds; Mass Spectrometry; Metals, Heavy; Oxidation-Reduction; Porosity; Silicon; Silver Compounds; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Zinc Compounds