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Preparation Techniques
Published in Mihir Kumar Purkait, Randeep Singh, Membrane Technology in Separation Science, 2018
Mihir Kumar Purkait, Randeep Singh
For polymeric membranes, polymers such as polysulfone, poly(vinylidene fluoride), and cellulose are used as base polymers for the fabrication of polymeric membranes using various preparation methods, such as phase inversion. These polymers induce chemical and mechanical stability to the prepared membranes. Similarly, materials such as polymers, nanoparticles, carbon nanotubes, and modified or responsive materials are used as additives so as to improve the membrane properties such as hydrophilicity and antifouling nature. On the other hand, polymers like poly(ethylene glycol) and poly(vinyl alcohol) are used as pore formers, which induce pore formation in the membranes. In the case of ceramic membranes, materials such as zirconia, kaolin, and quartz are used as base materials for the fabrication of a ceramic membrane. Materials, such as sodium metasilicates are used as binders, which enhance the mechanical strength. Similarly, boric acid and sodium carbonate are used for improving the dispersion of the inorganic precursors used for the fabrication of ceramic membranes. Therefore, the choice of material for the membrane precursor is very important, as the attributes of the fabricated membranes directly depend on the properties of these materials. Thus, membrane materials should be chosen accordingly, mainly based upon the demands and requirements of the membrane application.
Poultry Feeding Operations
Published in Frank R. Spellman, Nancy E. Whiting, Environmental Management of Concentrated Animal Feeding Operations (CAFOs), 2007
Frank R. Spellman, Nancy E. Whiting
Important point: The majority of eggs marketed commercially in the United States are washed using automatic washers. Cleaning compounds, such as sodium carbonate, sodium metasilicate, or trisodium phosphate, together with small amounts of other additives, are commonly used in these systems. Wash water is contaminated with shell, egg solids, dirt, manure, and bacteria washed from the egg surface into the recycled water. Eggs may be washed either on-farm or off-farm. Over three-fourths of layer farms process eggs off-farm, and one-third of the largest farms are likely to wash eggs off-farm. Operations that wash their eggs on-farm may do so in-line or off-line. Larger operations commonly collect and store egg wash water on site in large tanks or lagoons for treatment and storage.
Activated Silica as a Flocculation Aid
Published in Willy J. Masschelein, Unit Processes in Drinking Water Treatment, 2020
The preparation of activated silica remains based on the alkaline polymerization of partially neutralized sodium metasilicate. When passed through an acid-regenerated cation-exchange column, dilute solutions of sodium metasilicate produce, on standing, colloidal silica free from salts. This product (i.e., polysilicic acid with a degree of polymerization of 3 to 7 at a pH of 2 to 3) (13) has little or no value in promoting flocculation or the strengthening of flocs. On dilution, depolymerization occurs, partially regenerating the orthosilicic acid. By adding alkali to a suspension of acid-induced polymerization of orthosilicic acid, depolymerization occurs but is followed by rapid repolymerization, releasing an active product (14).
Deriving optimal and adaptive nanoparticles-assisted foam solution for enhanced oil recovery applications: an experimental study
Published in Journal of Dispersion Science and Technology, 2023
Hamid Reza Afifi, Saber Mohammadi, Siyamak Moradi, Elaheh Hamed Mahvelati, Fatemeh Mahmoudi Alemi, Omid Ghanbarpour
According to the experiments, the presence of the nanoparticles in the foam solution has caused the formation of foam with stronger texture and smaller bubbles with high resistance, which resulted in more stable foam structure. Thus, the gas phase in the foam could not easily escape from the bubbles and the foam structure is highly stable. Foam solution containing nanoparticles has a stronger texture than a solution without the nanoparticles (Figure S5 in Supplementary material). However, in the foam solution free of nanoparticles, the bubbles have lower resistance and the size of the bubbles is often large, which has lower stability compared to the solution with the nanoparticles. These results demonstrate that the enhancement of the foam stability in the presence of the silica nanoparticles is more pronounced than the case of Fe2O3 nanoparticles. This can be assigned to the higher specific surface area of the silica, as obtained through the BET measurements (Table 2). Higher surface area of silica nanoparticles results in more adhesion of these particles to the surface of the gas bubbles, which has also been able to increase its viscosity. As well, at high temperatures, a reaction can take place between the silica nanoparticles and sodium chloride to produce sodium metasilicate (Na2SiO3). Due to its foaming properties, this salt may improve the stability of the foam.[40] However, this theory needs further study and experimental investigation. Due to the fact that the charge on the surfactant and silica nanoparticles is negative, electrostatic interactions between these two substances can affect the adsorption phenomenon of the surfactant and greatly increase the amount absolute zeta potential.[41] Meanwhile, repulsion between the surfactant and SiO2 causes more adsorption of surfactant molecules to further reduce the amount of interfacial tension.[42]