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Spinel Ferrites—A Future Boon to Nanotechnology- Based Therapies
Published in Nandakumar Kalarikkal, Sabu Thomas, Obey Koshy, Nanomaterials, 2018
R Sharath, Nagaraju Kottam, H Muktha, K Samrat, M. Chandraprabha, R Harikrishna, Bincy Rose Vergis
Spinel ferrites have been prepared by reverse micelle micro emulsion method. In this method, NPs synthesis involves preparation of aqueous solution of precursor material (nitrate salts) with addition of a surfactant (sodium dodecyl sulfate (SDS), cetrimonium bromide (CTAB), Triton-X 100, Tween 80, or polysorbate 80), and toluene to form a reverse micelles. This solution is then refluxed following removal of excess toluene through distillation; the resulting brown particles are then washed with water and ethanol to ensure that any excess surfactant is removed. The solution mixture is subjected to centrifugation and particles are collected. The sample is annealed at a ramping rate which results in a fine black powder. The size of the particles can be varied by adjusting the water to toluene ratios.
Applications of Glass Micro- and Nanospheres
Published in Giancarlo C. Righini, Glass Micro- and Nanospheres, 2019
Giancarlo C. Righini, Francesco Prudenzano
Mesoporous silica nanoparticles (MSN) [106] and mesoporous bioactive glass (MBG) nanospheres [107] (MBG) possess excellent properties in terms of high surface area (for enhanced adsorption), large pore volume (for high biomolecular loading), tunable pore size with a narrow distribution (permitting the site selection of the drugs), and good chemical and thermal stability. Figure 8.17 depicts the different levels of pore sizes which may be exploited to construct the scaffold for bone repair [108] or for drug loading and controlled release [107]. Several patents were granted, concerning the fabrication of solid or hollow microspheres with porous surfaces [109–111]. Mesoporous silica nanoparticles can be prepared by sol–gel, and their size, morphology, and dispersion can be varied by changing simultaneously the water content and the amount of surfactant [112]. Figure 8.18 shows the field emission scanning electron microscopy (FESEM) images of mesoporous silica particles obtained when using different amounts and/or ratios of water and cetrimonium bromide (CTAB) surfactant. It appears clear that morphology and size may vary in a significant way: while the reference particle (a), obtained by using 0CTAB:45H2O, exhibits a perfect spherical shape with an average diameter of 740 nm, the silica particles (b, c), prepared with the same molar ratio of water/TEOS = 45 but with different amounts of CTAB, show a more irregular shape and a wider size distribution, ranging from 150 to 750 nm. Using a higher amount of CTAB, one observes that the nanoparticles tend to group and their morphology evolves from a spherical to an ellipsoidal shape, up to an elongated rod (d, e).
Assessment of Oil Fouling by Oil–Membrane Interaction Energy Analysis
Published in Olayinka I. Ogunsola, Isaac K. Gamwo, Solid–Liquid Separation Technologies, 2022
Henry J. Tanudjaja, Jia W. Chew
Zhang et al. compared the interaction between oil emulsion and polymer (APAM) with a PTFE MF membrane via the XDLVO energy analysis during the treatment of alkali/surfactant/polymer (ASP) flooding oilfield wastewater [46]. The APAM or anion polyacrylamide had a less negative interaction energy with the membrane compared to oil–membrane interaction, which underlie the more significant fouling by the crude oil emulsion among the other foulants in ASP wastewater. As for foulant–foulant interaction energy, the oil–oil interaction was more attractive than that of other foulants, which agreed with the severe oil fouling at the later stage of the filtration. It was observed also that the presence of salinity and surfactant made the total interaction energy less attractive, which hence mitigated fouling. OCT was employed by Trinh et al. to study the effect of surfactant on oil fouling in conjunction with the DLVO-XDLVO energy analysis [22]. Anionic, cationic, and nonionic surfactants were used to give different charges on the oil emulsions, which were filtered with PVDF MF membranes in a dead-end setup. From the analysis of the OCT images, it was observed that the nonionic surfactant-stabilized oil emulsion (Tween 20) had the most extensive fouling in comparison to the other positively and negatively charged oil emulsion (cetrimonium bromide-CTAB and SDS, respectively) observed from the highest increase of the fouling voxel fraction along the filtration time, as shown in Figure 7.5a–c. All the DLVO of the oil–membrane interaction energies showed repulsive interaction, with the nonionic surfactant being the least repulsive, thus leading to more significant fouling. Although the XDLVO energies were attractive at separation distances below 5 nm, nonionic surfactant-stabilized oil emulsion had the least repulsion force, facilitating deposition, as shown in Figure 7.5d and e.
Wettability alteration of carbonate reservoir rock using amphoteric and cationic surfactants: Experimental investigation
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Yaser Souraki, Erfan Hosseini, Ali Yaghodous
Two surfactants, one new amphoteric and one cationic surfactant were used in this experimental study. Initial surfactant is HABSA which is the recognized amphoteric surfactant. HABSA formulation is (C16H33C6H3NH2SO3H) that shows, when it dissolves in water, it contains two charged groups of different sign at its head and a long alkyl tail. The second used surfactant was cetrimonium bromide ((C16H33)N(CH3)3Br, cetyl trimethyl ammonium bromide, CTAB) which is one of the components of the topical antiseptic cetrimide. Figure 1b shows surfactants. These surfactants were acquired from Merck Company. These surfactants were dissolved in water and their critical micelle concentration (CMC) were measured. Chemical structures of HABSA and CTAB are shown in Figure 1c–d.
Lubricating and physico-chemical properties of CI- 4 plus engine oil dispersed with surface modified multi-walled carbon nanotubes
Published in Tribology - Materials, Surfaces & Interfaces, 2018
V. Srinivas, Ch. Kodanda Rama Rao, N. Mohan Rao
As the MWCNTs tend to agglomerate and form large particles clusters, it is required to modify the surface of MWCNTS with a surfactant to create stearic repulsions between individual nanotubes. To stabilise the nano particles in the liquid medium, two kinds of surfactants: SPAN 80 and Cetrimonium bromide (CTAB) are used to modify the surface of MWCNTs during the preparation of oil. Span80 is a nonionic surfactant with a hydrophilic-lipophilic balance of 4·6 which is ideally suitable for oils. Cetrimonium bromide (CTAB) is a quaternary ammonium nonionic surfactant. It adsorbs on the surface of nanoparticles reducing their surface energy thereby preventing aggregation and settling of nanoparticles.