Flame Retardant Nano-Structured Fillers from Huntite/Hydromagnesite Minerals.

In the current study, we propose a simple hydrothermal pathway to synthesize nano-structured Mg(OH)2 after application of thermal decomposition followed by hydration of commercial minerals based on hydromagnesite and huntite. The synthesis of nano-materials is performed without the use of any catalyst. The effect of decomposition temperature on the hydrothermal synthesis of Mg(OH)2 is extensively studied. It is shown that the morphology of resulting structures consists typically of particles ~200 nm in diameter and ~10 nm in thickness. Study of the structure at the molecular level designates the composition and supports the nano-sized characteristics of the produced materials. The associated thermal properties combined with the corresponding optical properties suggest that the material may be used as a flame retardant filler with enhanced transparency. In this concept, the flame retardancy of composite coatings containing the produced nano-sized Mg(OH)2 was examined in terms of limiting oxygen index (LOI), i.e., the minimum concentration of oxygen that just supports flaming combustion.

Poly(ethylene oxide)-Based Copolymer-IL Composite Membranes for CO2 Separation.

Poly(ethylene oxide) (PEO)-based copolymers are at the forefront of advanced membrane materials for selective CO2 separation. In this work, free-standing composite membranes were prepared by blending imidazolium-based ionic liquids (ILs) having different structural characteristics with a PEO-based copolymer previously developed by our group, targeting CO2 permeability improvement and effective CO2/gas separation. The effect of IL loading (30 and 40 wt%), alkyl chain length of the imidazolium cation (ethyl- and hexyl- chain) and the nature of the anion (TFSI-, C(CN)3-) on physicochemical and gas transport properties were studied. Among all composite membranes, PEO-based copolymer with 40 wt% IL3-[HMIM][TFSI] containing the longer alkyl chain of the cation and TFSI- as the anion exhibited the highest CO2 permeability of 46.1 Barrer and ideal CO2/H2 and CO2/CH4 selectivities of 5.6 and 39.0, respectively, at 30 °C. In addition, almost all composite membranes surpassed the upper bound limit for CO2/H2 separation. The above membrane showed the highest water vapor permeability value of 50,000 Barrer under both wet and dry conditions and a corresponding H2O/CO2 ideal selectivity value of 1080; values that are comparable with those reported for other highly water-selective PEO-based polymers. These results suggest the potential application of this membrane in hydrogen purification and dehydration of CO2 gas streams.

Application of Sorbents for Oil Spill Cleanup Focusing on Natural-Based Modified Materials: A Review.

Conventional synthetic sorbents for oil spill removal are the most widely applied materials, although they are not the optimal choices from an economic and environmental point of view. The use of inexpensive, abundant, non-toxic, biodegradable, and reusable lignocellulosic materials might be an alternative to conventional sorbents, with obvious positive impact on sustainability and circular economy. The objective of this paper was to review reports on the use of natural-based adsorbing materials for the restoration of water bodies threatened by oil spills. The use of raw and modified natural sorbents as a restoration tool, their sorption capacity, along with the individual results in conditions that have been implemented, were examined in detail. Modification methods for improving the hydrophobicity of natural sorbents were also extensively highlighted. Furthermore, an attempt was made to assess the advantages and limitations of each natural sorbent since one material is unlikely to encompass all potential oil spill scenarios. Finally, an evaluation was conducted in order to outline an integrated approach based on the terms of material-environment-economy.

Transfer of metals in the liquids of electronic cigarettes.

Objectives: E-cigarettes are electronic devices containing a liquid that usually consists of a mixture of glycerol, propylene glycol and nicotine, with or without flavorings, in various concentrations. A vapor or aerosol is produced, and inhaled from the user, when this liquid is heated by a heating coil. This work examines the impact of three parameters (e-liquid composition, nicotine content and air flow) on the transfer of metals' from the heating coils to the e-liquids.Materials and methods: A distillation unit was used, where 20ml of an e-liquid were boiled with two commercial heating elements. Four e-liquids: 100% Propylene Glycol, 100% Glycerol, 50/50% Propylene Glycol/Glycerol, 33.3/33.3/33.3% Propylene Glycol/Glycerol/Water, three nicotine contents: 0, 0.4 and 0.8% per volume and three air flows: 0, 0.5 and 1.0 L/min, were used. The liquids were analyzed by Total Reflection X-Ray Fluorescence spectrometry to determine the final content of metals.Results and discussion: Five metals, Fe, Ni, Cu, Zn, and Pb, were found to be transferred from the heating coils to the e-liquids. The transfer of those metals increases with air flow and nicotine concentration, while e-liquid composition also has a significant impact. Glycerol enhances the transfer of metals compared to propylene glycol and their mixtures. The boiling temperature of the e-liquids increases significantly the transfer of metals in the e-liquids.Conclusions: There is a transfer of metals from the heating coils to the e-liquids. This transfer depends on the e-liquid composition and on the boiling temperature.

Synthesis of Imidazolium based PILs and Investigation of Their Blend Membranes for Gas Separation.

Polymeric (ionic liquid) (PIL) copolymers bearing cationic imidazolium pendants and polar acrylic acid groups (P(VBCImY-co-AAx)), which both favor the interaction with CO2 molecules, have been synthesized and blended with film forming, high glass transition temperature aromatic polyether-based pyridinium PILs (PILPyr). The blend membranes based on the above combination have been prepared and characterized in respect to their thermal and morphological behavior as well as to their gas separation properties. The used copolymers and blends showed a wide range of glass transition temperatures from 32 to 286 °C, while blends exhibited two phase morphology despite the presence of polar groups in the blend components that could participate in specific interactions. Finally, the membranes were studied in terms of their gas separation behavior. It revealed that blend composition, counter anion type and acrylic acid molar percentage affect the gas separation properties. In particular, PILPyr-TFSI/P(VBCImTFSI-co-AA20) blend with 80/20 composition shows CO2 permeability of 7.00 Barrer and quite high selectivity of 103 for the CO2/CH4 gas pair. Even higher CO2/CH4. selectivity of 154 was achieved for PILPyr-BF4/P(VBCImBF4-co-AA10) blend with composition 70/30.

New Pyridinium Type Poly(Ionic Liquids) as Membranes for CO2 Separation.

New pyridinium based PILs have been prepared by modification of their precursors based on high molecular weight aromatic polyethers bearing main chain pyridine units. The proposed methodology involves the conversion of the precursors to their ionic analogues via N-methylation reaction, followed by anion exchange methathesis reaction to result in PILs with the desirable anions (tetrafluoroborate and bis(trifluoromethylsulfonyl)imide). These PILs show excellent thermal stability, excellent mechanical properties, and most importantly can form very thin, free standing films with minimum thickness of 3 µm. As expected, the PIL containing the TFSI- anion showed improved CO2 and CH4 permeabilities compared to its analogue containing the BF4-. PIL-IL composites membranes have also been prepared using the same PIL and different percentages of pyridinium based IL where it was shown that the membrane with the highest IL weight percentage (45 wt %) showed the highest CO2 permeability (11.8 Barrer) and a high CO2/CH4 ideal selectivity of 35 at room temperature.