Insights into the influence of temperature on the adsorption behavior of sodium oleate and its response to flotation of quartz

Temperature affects the flotation of quartz in the calcium/sodium oleate(Na OL)system,while there is a lack of understanding of its potential mechanism.Therefore,in this work,the flotation response of quartz to temperature was investigated via micro-flotation experiments,interface property analyses,and theoretical calculations.Flotation results demonstrated that increasing temperature contributed to higher flotation recovery of quartz,which enhanced the removal of quartz from hematite.Surface tension results revealed that higher temperatures lowered the critical micelle concentration(CMC)and surface tension of the Na OL solution,and thus enhanced its surface activity.Solution chemistry calculations and X-ray photoelectron spectroscopy(XPS)measurements confirmed that the increased content of Ca(OH)+achieved by increasing temperatures enhanced the adsorption amounts of calcium species(acting as activation sites)on the quartz surface.Dynamic light scattering(DLS)measurements verified that the association degree of RCOOàto form(RCOO)22àwas strengthened.Furthermore,adsorption density measurements and molecular dynamics(MD)simulations confirmed that increasing the temperature facilitated Na OL adsorption toward the surface of the quartz,which was attributed to the stronger interaction between Na OL and the calcium-activated quartz surface at higher temperatures.As a result,quartz flotation was improved by increasing temperatures.Accordingly,a possible adsorption model was proposed.

EFFECT OF SODIUM OLEATE ON FLOTATION OF MAGNESITE

Laboratory studies were made on the floatabil-ity of magnesite and dolomite with sodium oieate as the collector. The adsorption mechanism of sodium oieate on the surface of minerals was examined. The results show that the ion-molecule association polymer of oieate in the pulp is a main active component of the collector . In both neutral and basic media , the adsorption type of sodium oieate on the surface of carbonate minerals is mainly chemisorp-tion, forming Mg(Ol)2 and Mg(Ol)2·HOl.

Solution chemistry of carbonate minerals and its effects on the flotation of hematite with sodium oleate

The effects of carbonate minerals（dolomite and siderite） on the flotation of hematite using sodium oleate as a collector were investigated through flotation tests, supplemented by dissolution measurements, solution chemistry calculations, zeta-potential measurements, Fourier transform infrared（FTIR） spectroscopic studies, and X-ray photoelectron spectroscopy（XPS） analyses. The results of flotation tests show that the presence of siderite or dolomite reduced the recovery of hematite and that the inhibiting effects of dolomite were stronger. Dissolution measurements, solution chemistry calculations, and flotation tests confirmed that both the cations（Ca^（2＋） and Mg^（2＋）） and CO_3^（2＋）ions dissolved from dolomite depressed hematite flotation, whereas only the 23CO-ions dissolved from siderite were responsible for hematite depression. The zeta-potential, FTIR spectroscopic, and XPS analyses indicated that Ca^（2＋）, Mg^（2＋）, and CO_3^（2-）（HCO_3^-） could adsorb onto the hematite surface, thereby hindering the adsorption of sodium oleate, which was the main reason for the inhibiting effects of carbonate minerals on hematite flotation.

Rheological behavior of mixed system of ionic liquid [C8mim]Br and sodium oleate in water

Abstract We report on the rheological behavior of wormlike micelles constructed by ionic liquid surfactant [Csmim]Br （1-octyl-3-methylimidazolium bromide） and anionic surfactant sodium oleate （NaOA） in aqueous solution. The effects of surfactant composition, total surfactant concentration, added salts, and temperature were investigated. The prevailing surfactant effect at lower concentration and the leading cosolvent effect at higher concentration of [Csmim]Br may be the main reasons for appearance of well-established maximum in key rheologi- cal parameters with variation of surfactant composition and total surfactant concentration. The Cole-Cole plots demon- strate that the systems （total surfactant concentration falls within 0.17-0.35 mol. L- 1 and molar ratio 0.33≤R ≤ 0.50） fit the Maxwell＇s mechanical model as linear viscoelastic fluid. The addition of NaBr or sodium salicylate decreases significantly the viscosity and the relaxation time of the wormlike micelle solution but cannot change the value of plateau modulus Go. The present system has low rheological tolerance to temperature. The increase of temperature decreases the average contour length and viscosity of wormlike micelles and thus strengthens the relaxation progress of diffusion and weakens the relaxation progress of reptation. Increasing the temperature also decreases the value of plateau modulus G0 and shifts the minimum value of the loss modulus G″min to higher frequencies.

Lamellar liquid crystal polymerization of sodium oleate/oleic acid/octadiene/water system

In the lamellar liquid crystallization (LLC) phase of NaOL/ OLA/H2O system, the small angle X-ray diffraction measurements show that the oleic add is solubilized in the oil layer at first and men into the amphiphile layer. The octadiene added is also located partly in the oil layer and partly in the amphiphile layer in the LLC. With the addition of octadiene as cross-linking agent, roe LLC phase of NaOL/OLA/H2O system was polymerized under the initiation of AIBN with the protection of pure nitrogen at 60°C. Most of the double bond absorption of the monomers in IR spectra disappeared after polymerization. The polymerization takes place not only in the middle of the amphiphile layer between the double bonds of NaOL or OLA and those of octadiene, but also in the oil layer of LLC between the double bonds of OLA and those of octadiene. Interlayer spacing measurements on the copolymer proved d values decreased by about 1 - 2 nm compared with those of the corresponding system before the polymerization, indicating a disruption of the ordered structure by the polymerization. The copolymer still has superior surface activity with the critical micellar concentration (CMC) decreased almost to the half of the value for the system before the polymerization.

An Efficient Route to Prepare Metal Organosols by Phase Transfer Procedure

Silver and gold organosols are easily prepared by transferring nanoparticles from aqueous phase into isooctane with high efficiency (>90%). Concentrations of sodium oleate and magnesium chloride have crucial effects on the transfer efficiency. Based on the UV-visible absorption spectra, TEM micrographs of nanoparticles, as well as molecular modeling calculation about the adsorption conformation of sodium oleate molecules, a possible phase transfer mechanism is proposed.

Synthesis and application of bilayer-surfactant-enveloped Fe_3O_4 nanoparticles: water-based bilayer-surfactant-enveloped ferrofluids

Superparamagnetic carbon-coated Fe3O4 nanoparticles with high magnetization（85 emu·g-（-1）） and high crystallinity were synthesized using polyethylene glycol-4000（PEG（4000）） as a carbon source.Fe3O4 water-based bilayer-surfactant-enveloped ferrofluids were subsequently prepared using sodium oleate and PEG（4000） as dispersants.Analyses using X-ray photoelectron spectroscopy,X-ray diffraction,and Fourier-transform infrared spectroscopy indicate that the Fe3O4 nanoparticles with a bilayer surfactant coating retain the inverse spinel-type structure and are successfully coated with sodium oleate and PEG（4000）.Transmission electron microscopy,vibrating sample magnetometry,and particle-size analysis results indicate that the coated Fe3O4 nanoparticles also retain the good saturation magnetization of Fe3O4（79.6 emu·g^-1） and that the particle size of the bilayer-surfactant-enveloped Fe3O4 nanoparticles is 42.97 nm,which is substantially smaller than that of the unmodified Fe3O4 nanoparticles（486.2 nm）.UV-vis and zeta-potential analyses reveal that the ferrofluids does not agglomerate for 120 h at a concentration of 4 g·L^-1,which indicates that the ferrofluids are highly stable.