Magnetite Particles In Water Research Articles

Functional modification of mussel adhesive protein to control solubility and adhesion property

Marine mussels produce strong underwater adhesives called mussel adhesive proteins (MAPs) that can adhere to a variety of surfaces under physiological conditions. Thus, MAPs have been investigated as a potentially sustainable alternative to conventional petrochemical-based adhesives. Recombinant MAPs would be promising for large-scale production and commercialization; however, MAPs are intrinsically adhesive, aggregative, and insoluble in water. In this study, we have developed a solubilization method for the control of MAP adhesion by fusion protein technique. Foot protein 1 (Fp1), a kind of MAP, was fused with the highly water-soluble protein, which is the C-terminal domain of ice-nucleation protein K (InaKC), separated by a protease cleaving site. The fusion protein exhibited low adhesion but high solubility and stability. Notably, Fp1 recovered its adhesive property after removal from the InaKC moiety by protease cleaving, which was evaluated and confirmed by the agglomeration of magnetite particles in water. The ability to control adhesion and agglomeration makes MAPs favorable prospects for bio-based adhesives.

Effect of coexisting components on phosphate adsorption using magnetite particles in water.

In this study, we focused on the rate of adsorption of phosphate on to the surface of magnetite in the presence of coexisting anions, organic matters and heavy metals. Magnetite particles were prepared using a co-precipitation method. Iron (II) sulfate heptahydrate and iron (III) chloride hexahydrate were mixed and then a sodium hydroxide solution was added drop-wise in the mixed iron solution. Coexisting anions were found to have no effect on the decrease in phosphate adsorption. However, phosphate adsorbed on to magnetite surface decreased with increasing total organic carbon (TOC) concentration of natural organic matter (NOM) such as citric, oxalic, and humic acid. The amount of phosphate adsorbed rapidly decreased with the increase of NOM concentration; therefore, it can be noted that NOM concentration considerably affects the adsorption of phosphate due to the negative charge exiting on the surface of NOMs. Glucose and ethanol, meanwhile, were found to have no effect on the phosphate adsorption. The amount of phosphate adsorbed did not change in the presence of heavy metals, namely, Pb and Cd, under acidic conditions. However, under alkaline conditions, the amount of phosphate adsorbed decreased with increasing concentrations of Pb and Cd. In the case of coexisting As(III), the amount of phosphate adsorbed decreased at all pH levels with increasing As(III) concentrations.

Monitoring Local Solids Fraction Variations in Multiphase Flow using Pulse-echo Ultrasound

This paper presents an ultrasonic pulse-echo technique for on-line monitoring of variations in solids concentrations in particle suspensions. The method is based on time-frequency analysis of the backscatter signals, exploring variations in spectral content of the backscatter as function of depth in the suspension. Experiments on a settling of magnetite particles in water, at varying solids concentrations, show that the settling process can be followed by studying the energy of backscattered ultrasound.

SOLVOTHERMAL SYNTHESIS OF UNIFORM MAGNETITE MICROSPHERES

Facile procedures to synthesize large quantities of uniform and well dispersed magnetite particles in water were developed through a solvothermal method. Magnetite microspheres were obtained by using FeCl 3 · 6H 2 O , urea and polyethylene glycol as the starting materials in ethylene glycol at 200°C for 8 h. The samples were characterized by using X-ray diffraction, transmission electron microscopy, scanning electron microscopy and vibrating sample magnetometry. Experimental results revealed that the particles were well dispersed with uniform particle size and diameters in the range 260 to 280 nm. The saturation magnetization value was 71.5 emu/g with negligible remanence.

Nanocomposite particles with core–shell morphology II. An investigation into the affecting parameters on preparation of Fe 3O 4-poly (butyl acrylate–styrene) particles via miniemulsion polymerization

The encapsulation of inorganic particles with polymers is desirable for many applications in order to improve the stability of the encapsulated products and disperse ability in different media. Colloidal particles with magnetic properties have become increasingly important both technologically and for fundamental studies. This is due to their tunable anisotropic. In the absence of an applied magnetic field, the particles have isotropic sphere dispersion, whereas in an external magnetic field the particles form anisotropic structures. Here, latexes containing nanocomposite particles of styrene–butyl acrylate/Fe 3O 4 with core–shell structure were prepared through miniemulsion polymerization technique. Magnetic composite nanospheres with high magnetic content were synthesized through miniemulsion polymerization using a new process based on a three-steps preparation route including two miniemulsion processes: (1) preparing a dispersion of oleic acid coated magnetite particles in water; (2) mixing of modified magnetite particles with styrene/butyl acrylate in the presence of sodium dodecyl sulfate (SDS), sorbitane mono oleate (Span 80), hexadecane (HD) and (3) miniemulsification of the modified Fe 3O 4 into the monomer droplets to reach to complete encapsulation. Subsequent polymerization generated magnetic nanocomposite spheres. Hence, the copolymerization reaction was performed on the surface of such particles in order to obtain core–shell morphology for these nanoparticles, which were characterized by several techniques such as TEM, SEM, DLS, TGA, VSM and FT-IR. The magnetic copolymer particles with diameter of 120–170 nm were obtained. The effect of several parameters such as magnetite, surfactants and hydrophobe amounts on the stability, particle size and magnetization were investigated and also optimized.

Ferrofluid catalyzed water gas shift reaction to give carbon-dioxide and hydrogen

A ferrofluid consisting of colloidally dispersed magnetite particles in water was found to be an efficient selective catalyst for water gas shift reaction at 15–25 atmosphere of CO pressure in the temperature range of 423–553 K where the products obtained were only CO2 and H2. The reaction was studied as a function of variation of the concentration of catalyst, pressure of CO gas and temperature. Kinetic parameters suggested a mechanism involving first order dependence in CO and catalyst concentrations.

Surfactants having polyfluoroalkyl chains. II. Syntheses of anionic surfactants having two polyfluoroalkyl chains including a trifluoromethyl group at each tail and their flocculation-redispersion ability for dispersed magnetite particles in water

Anionic surfactants having two polyfluoroalkyl chains per molecule, i.e. the sodium salt of bis(1 H, 1 H, 2 H,2 H-heptadeca-fluorodecyl)-2-sulfosuccinate, CF 3(CF 2) 7(CH 2) 2OCOCH 2CH(SO 3Na)COO(CH 2) 2(CF 2) 7CF 3, the sodium salt of bis(1 H, 1 H, 2 H, 2 H-tridecafluoro-octyl)-2-sulfosuccinate, CF 3(CF 2) 5(CH 2) 2OCOCH 2CH(SO 3Na)COO(CH 2) 2(CF 2) 5CF 3, and the sodium salt of bis(1 H, 1 H, 2 H, 2 H-nonafluorohexyl)-2-sulfosuccinate, CF 3(CF 2) 3(CH 2) 2OCOCH 2CH(SO 3Na)COO(CH 2) 2(CF 2) 3CF 3, have been prepared from maleic anhydride, the corresponding alcohols possessing a polyfluoroalkyl chain and sodium hydrogen sulfite. The flocculation and redispersion abilities of these surfactants for dispersed magnetic particles in water have been examined to investigate the effect of the chain length. It was found that this ability was enhanced by an increase in the chain length. The contact angles for water for pelleted surface-modified magnetite have been measured. In order to compare this ability and the contact angles, data for other fluorinated surfactant have been obtained. The Kraff point, the surface tension and the pNa of the aqueous surfactant solutions have also been measured.

Syntheses of Anionic Surfactants Having Two Polyfluoroalkyl Chains and Their Flocculation Ability for Dispersed Magnetite Particles in Water

Abstract Four anionic surfactants having two polyfluoroalkyl chains in a molecule, sodium salt of bis(1H,1H,2H,2H-heptadecafluorodecyl) 2-sulfosuccinate, CF3(CF2)7(CH2)2OCOCH2CH(SO3Na)COO(CH2)2(CF2)7CF3, sodium salt of bis(1H,1H,9H-hexadecafruorononyl) 2-sulfosuccinate, H(CF2)8CH2OCOCH2CH(SO3Na)COOCH2(CF2)8H, sodium salt of bis(1H,1H,7H-dodecafluoroheptyl) 2-sulfosuccinate, H(CF2)6CH2OCOCH2CH(SO3Na)COOCH2(CF2)6H and sodium salt of bis(1H,1H,5H-octafluoropentyl) 2-sulfosuccinate, H(CF2)4CH2OCOCH2CH(SO3Na)COOCH2(CF2)4H, were prepared from maleic anhydride, the corresponding alcohols having a polyfluoroalkyl chain and sodium hydrogensulfite. The flocculation and redispersion abilities of these surfactants against dispersed magnetite particles in water have been examined in comparison with other four anionic surfactants having a single polyfluoroalkyl chain in a molecule; sodium pentadecafluorooctanoate, CF3(CF2)6COONa, sodium 9H-hexadecafluorononanoate, H(CF2)8COONa, sodium 7H-dodecafluoroheptanoate, H(CF2)6COONa, and sodium 5H-octafluoropentanoate, H(CF2)4COONa. These abilities were estimated by measurement of the contact angle against water using pelleted surface-modified magnetite. The abilities of the surfactants having two polyfluoroalkyl chains against flocculation-redispersion were superior to those of the surfactants having one polyfluoroalkyl chain. Especially, sodium salt of bis(1H,1H,2H,2H-heptadecafluorodecyl) 2-sulfosuccinate was the most effective surface active agent for these abilities.