| 1. |
- Ismail, Norafiqah, et al.
(författare)
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Experimental and theoretical studies on the formation of pure β-phase polymorphs during fabrication of polyvinylidene fluoride membranes by cyclic carbonate solvents
- 2021
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Ingår i: Green Chemistry. - : Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 23:5, s. 2130-2147
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Tidskriftsartikel (refereegranskat)abstract
- The use of highly toxic solvents presents significant risks to both the environment and human health. Therefore, the adoption of green solvents will be crucial for achieving sustainable membrane production. This work reports the use of inexpensive environmentally friendly biobased and biodegradable cyclic carbonate solvents, namely ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC), to fabricate polyvinylidene fluoride (PVDF) membranes. The solvent dependence of the phase inversion mechanisms, morphology, crystalline structures, and polymorphism of the prepared PVDF membranes were investigated. Polymorph analysis revealed that membrane fabrication in EC or PC yielded exclusively the β-phase product, whereas PVDF membrane fabrication in BC yielded a mixture of α and β phase material. The mechanism of β-phase formation was investigated using molecular dynamics simulation and shown to depend on the extent of hydrogen bonding at the polymer–solvent interface. The PVDF membrane formed in EC exhibited the highest porosity and pure water permeability, and was therefore tested in direct contact membrane distillation (DCMD), exhibiting promising results in terms of permeate flux and salt rejection. These results suggest that large-scale production of piezoelectric PVDF membranes using green solvents should be practically feasible.
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| 2. |
- Ismail, Norafiqah, et al.
(författare)
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Non-ionic deep eutectic solvents for membrane formation
- 2022
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Ingår i: Journal of Membrane Science. - : Elsevier. - 0376-7388 .- 1873-3123. ; 646
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Tidskriftsartikel (refereegranskat)abstract
- Deep eutectic solvents (DES) have recently emerged as a new class of inexpensive biodegradable solvents and additives with diverse applications. In this study, a new family of non-ionic deep eutectic solvents (NIDES) is proposed for the first time for membrane preparation. Three types of NIDES, N-methylacetamide-acetamide (DES-1), N-methyl acetamide-N-methyl urea (DES-2), and N-methyl acetamide-N,N′-dimethyl urea (DES-3) were synthesized and used to dissolve polyvinylidene fluoride (PVDF) polymer. The effects of the additive polyvinylpyrrolidone (PVP) and the type of NIDES on the PVDF membrane characteristics, water permeability and bovine serum albumin (BSA) separation were studied. The membranes prepared with DES-1 and 2 wt% PVP exhibited a good water permeate flux (96.82 L/m2.h) and a high BSA separation factor (96.32%). High performance PVDF membranes can thus be efficiently prepared using biodegradable inexpensive NIDES.
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| 3. |
- Rahmati-Ilkhchi, Mahmoud, et al.
(författare)
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Mid-Cimmerian, Early Alpine and Late Cenozoic orogenic events in the Shotur Kuh metamorphic complex, Great Kavir block, NE Iran
- 2010
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Ingår i: Tectonophysics. - : Elsevier BV. - 0040-1951 .- 1879-3266. ; 494:1-2, s. 101-117
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Tidskriftsartikel (refereegranskat)abstract
- The Shotur Kuh complex, exposed in the NE part of the Great Kavir block, is composed of amphibolite facies metaigneous rocks and micaschist, and of lower-grade Permian–Miocene cover sequences that experienced four main deformation phases and at least two metamorphic events. The D1 deformation phase is associated with a prograde metamorphism that in the basement reached amphibolite facies conditions. This Barrovian-type metamorphism with field gradient of 20–22 °C/km was related to collision-induced crustal thickening. The D2 event corresponds to post-collisional exhumational upflow of middle crust, resulting in updoming of the basement core and its top-to-the-Northwest unroofing along a low-angle detachment shear zone at the basement/cover boundary. The D1 and D2 events are considered as Mid-Cimmerian in age because they also affected the Upper Triassic–Lower Jurassic Shemshak Formation and are sealed by the Middle Jurassic conglomerates. The D3 folding event, characterised by NE–SW shortening, also affected the Cretaceous limestones, and it is sealed by Paleocene conglomerates. Considering the Late Cretaceous age of this deformation, it is related to the Late Cimmerian–Early Alpine orogeny that resulted from the Cenozoic closure of the Neo-Tethys oceanic tract(s) and convergence between the Arabian and Eurasian plates. The D4 folding event, characterised by NW–SE shortening, also affected the Miocene conglomerates, suggesting its Miocene or post-Miocene age. This deformation event is associated with Late Cenozoic convergence between Arabia and Eurasia, and it could be combined with a left-lateral activity along the Great Kavir fault-bounding system.
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