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Sodalite- and Chitosan-Based Composite Membrane Materials for Treatment of Metal-Containing Wastewater in Mining Operations
Published in Iqbal M. Mujtaba, Thokozani Majozi, Mutiu Kolade Amosa, Water Management, 2018
Machodi Mathaba, Michael O. Daramola
Membrane preparation employs various techniques depending on the material of construction and the final application. Normally, membrane materials are manufactured from synthetic polymers, although other forms such as ceramic (Sklari et al., 2015; Nędzarek et al., 2015) and metallic membranes have been used as membrane supports. The typical synthesis techniques used to prepare organic and inorganic membranes are sintering, stretching, and phase inversion (Drioli et al., 2006). The sintering technique normally produces symmetric ceramic or metallic membranes for UF and MF applications (Wu et al., 2013; Strathmann et al., 2010). The stretching technique normally produces polymeric membranes by stretching film or a hollow shaped homogeneous polymer with partial crystallinity perpendicularly to the axis of crystallite orientation (Bottino, 2009). Due to their intrinsic hydrophobicity, stretched membranes are used for vapor and gas separation rather than aqueous streams (Strathmann et al., 2010). The phase inversion method is most commonly used for the synthesis of polymeric membranes; it produces two distinct phases consisting of a polymer, solvent, and other additives by separating a homogeneous system.
Preparation Techniques
Published in Mihir Kumar Purkait, Randeep Singh, Membrane Technology in Separation Science, 2018
Mihir Kumar Purkait, Randeep Singh
The phase inversion technique is widely used in polymeric membrane preparation. It is the easiest, most secure, and time tested method to prepare various porous polymeric membranes for different applications. The steps involved in the phase inversion process are schematically shown in Figure 3.1. The method works by controlling the separation state of the two phases. The one with the concentrated phase, after the phase separation, is solidified immediately and results in the formation of a membrane. The structure and function of the prepared membrane depends upon the changes taken place during the time of phase separation and solidification. In general, phase inversion separation of a homogeneous polymeric solution takes place in a polymer-rich continuous phase and a polymer lean phase due to the thermodynamic instability caused by of the presence of external effects. The driving forces commonly used for the phase inversion or phase separation of the polymeric solutions are temperature (thermally induced phase separation), nonsolvent (nonsolvent-induced phase separation), evaporation (drying-induced phase separation), and nonsolvent vapor (vapor-induced phase separation). These phase inversion methods are explained in the following sections.
Phase Morphology of Dynamically Vulcanized Thermoplastic Vulcanizates
Published in Charef Harrats, Sabu Thomas, Gabriel Groeninckx, Micro- and Nanostructured Multiphase Polymer Blend Systems, 2005
Phase inversion is defined as a phenomenon whereby macroscopic conditions like mixing composition, viscosity, and surface tension change a continuous phase into a discontinuous phase. The phase inversion often happens in a zone containing a cocontinuous phase morphology, i.e., an area where both components of a binary blend interpenetrate and form an interpenetrating network–like phase morphology (dual continuity). Different authors found that phase inversion was dependent on the ratio of the blend composition (component fraction) and the ratio of the viscosities (29,30): () φ1φ2⋅η2η1=X
Formulation of roselle extract water-in-oil nanoemulsion for controlled pulmonary delivery
Published in Journal of Dispersion Science and Technology, 2023
Adil Omer Baba Shekh, Roswanira Abdul Wahab, Nur Azzanizawaty Yahya
Meanwhile, the nonionic surfactants Tween 80 (T80) and Span 80 (S80) were selected since the substance's high biological acceptability and lack of sensitivity to electrolyte concentration or pH,[44] while being recognized as safe and approved for use in certain pharmaceuticals, cosmetics, and food products.[45] Water-in-oil (w/o) NEs consist of a dispersed aqueous phase comprising small droplets, where the oil phase forms the continuous phase. In contrast, oil-in-water (o/w) NE is the dispersed phase distributed into the continuous water phase. In the phase inversion temperature method, an increase or decrease in temperature induces a phase inversion.[46] Thus, combining the high-energy and low-energy emulsification methods in a mixture of T80 and S80 could yield small and uniform roselle extract droplets. Adding the 0.9% (w/v) sodium chloride in the aqueous phase encourages smaller roselle extract droplets to form[47] and stabilizes the NE.
Effect of MgO on the microstructure and properties of mullite membranes made by phase-inversion tape casting
Published in Journal of Asian Ceramic Societies, 2021
Rafael Kenji Nishihora, Ellen Rudolph, Mara Gabriela Novy Quadri, Dachamir Hotza, Kurosch Rezwan, Michaela Wilhelm
The use of ceramic membranes has attracted much attention in separation technologies because of their superior chemical, thermal and mechanical stability compared to organic membranes [1]. Thus, ceramic membranes present extended lifespan even under extreme fouling and cleaning conditions, which would easily damage their organic counterparts [2]. There are numerous methods to prepare ceramic membranes such as slip casting, tape casting, extrusion, sol-gel, freeze casting, phase-inversion, etc. [3,4]. For instance, tape casting is a standard technique to prepare thin flat ceramic tapes [5,6]. This technique starts from homogeneous ceramic slurries, which are cast onto a substrate resulting in thin ”green tapes” after drying; and a consolidated ceramic tape after heat treatment [7]. In addition, phase inversion is one of the most popular techniques for the preparation of porous membranes, in which a polymer is dissolved in a suitable solvent and then formed into the desired shape in this process (thin film, tube, hollow fiber). The addition of a precipitant or nonsolvent (such as water) to this polymer solution causes the homogeneous phase to separate into a solid polymer (polymeric matrix) and a liquid solvent layer (porous network) [8,9].
Predicting phase inversion in agitated dispersions with machine learning algorithms
Published in Chemical Engineering Communications, 2021
In any stirred system containing a dispersed phase (dispersion or emulsion), the set of operating conditions may be such that, at a given phase composition, the dispersed phase becomes the continuous one and vice versa, a phenomenon called phase inversion (PI) (Norato et al. 1998). This particular moment can either be desired or prevented, depending on the application. For example, in the transport of heavy oil, water may be added in a ratio such that it may become the continuous phase as it flows through the pipeline, so that the dispersion viscosity may drop substantially, improving the transport energy costs (Arirachakaran et al. 1989).