A CO_(2)/N_(2)-Responsive Pickering Emulsion Stabilized by Novel Switchable Surface-Active Alumina Nanoparticles

This article reports the development of a novel switchable Pickering emulsion with rapid CO_(2)/N_(2) respon-siveness,which is stabilized using alumina nanoparticles hydrophobized in situ with a trace amount of a switchable superamphiphile via electrostatic interactions.With the introduction of CO_(2) for 30 s,the Pickering emulsion can be spontaneously demulsified with complete phase separation;the emulsion can then be reconstructed in response to N_(2) purging for 10 min followed by homogenization.Moreover,the stable Pickering emulsion can be stored for more than 60 days at room temperature with-out any visible change.The CO_(2)/N_(2)-responsive behavior of the switchable Pickering emulsion is attribu-ted to the reversible desorption/adsorption of the switchable surfactants on the surfaces of the alumina nanoparticles upon the alternative bubbling of CO_(2)or N_(2).Thanks to the simple fabrication of the surfac-tant and the hydrophobization of the alumina nanoparticles,this research has developed an extremely facile and cost-efficient method for preparing a rapidly CO_(2)/N_(2)-responsive switchable Pickering emul-sion.The dosage of the switchable surfactants has been significantly reduced by nearly 1500 times(from 150 to 0.1 mmol·L^(-1))as compared with the dosage used in previous studies.Moreover,the as-prepared CO_(2)/N_(2)-responsive switchable Pickering emulsion is environmentally friendly,mild,and nontoxic;thus,it holds great potential for practical applications with considerable economic and environmental benefits,such as oil transport,fossil fuel production,environmental gases detection,and the encapsulation and release of active ingredients.

Synthesis and Tribological Properties of Copper-alumina Nanocomposites Prepared by Coprecipitation Technique

The objective of this work is to study the synthesis of copper-alumina nanocomposites using the coprecipitation process and hot-pressing method, and investigate their mechanical properties. The effects of calcination temperature on the average size of composite particles and chemical composition after calcination were also analyzed. The sintering parameters including sintering temperature, hot pressure and packing time were optimized to fabricate the alumina nanoparticles reinforced copper matrix composites（CMCs）. The density, microhardness and tribological properties of the CMCs reinforced with 1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt% of alumina nanoparticles were investigated correspondingly. The results showed that the optimum preparation parameters for the CMCs were 900 ℃ of hot pressing temperature, 27.5 MPa of hot pressure and 2 hrs of packing time. The CMC reinforced with 2 wt% of alumina nanoparticles had the lowest wear rate, with the relative wear resistance of 3.13.

The Effect of Nano-Alumina Particles Generated in Situ in the Matrix of Ultralow and No Cement 85 wt%Al_(2)O_(3) Refractory Castables

Advanced high alumina refractory castables of ultra-low and to cement types, are well-known because of their ability on developing similar and/or superior thermal and mechanical properties. Following the recent trend of including nanoparticles in refractory castables, in this work, it is presented a novel way to obtain the benefit effects on the thermal and mechanical properties, promoted by the development in situ, of alumina’s nanoparticles in the matrix of castable (85 wt% Al2O3). The alumina nanoparticles were originated in situ after firing, due to the pyrolysis and oxidation of an aqueous resin, produced by the Pechini process. The resin played a double role, one as mixing liquid vehicle and the other as the aluminum oxide nanoparticles precursor. The results indicate a strong increase in flexural strength and elastic modulus as well as leading to a higher residual strength after thermal shock.

Microwave-assisted rapid synthesis of alumina nanoparticles using tea,coffee and triphala extracts

Alumina nanoparticles （A1NP） were synthe- sized from aluminium nitrate using extracts of tea, coffee and triphala--a well known herbal plant as well as a non- toxic and eco--friendly green material. The synthesis was carried out taking 1：4 ratio of metal salt and these extracts under microwave irradiations at 540 W, which gave better yield of nanoparticles. Water was taken as solvent medium. The formations of A1NP were initially monitored by the colour changes occurring in the reaction mixture during the incubation period. As synthesized nanoparticles were characterized by scanning electron microscope （SEM）, UV-Visible （UV-Vis） spectroscopy and Fourier transform infrared spectroscopy （FTIR）. The A1NP were found to be spherical in shape in case of tea and coffee extracts with a size of 50-200 nm and to be oval shaped in case of triphala extract with an average size of 200-400 nm. The formation of A1NP with the microwave-assistance using these plant extracts has proved to be very faster than any other methods. In addition, excellent reproducibility of these nanoparticles, without the use of any additional capping agent or stabilizer will have great advantages in compari- son with microbial synthesis, avoiding all the tedious and hygienic complications.

Effect of alumina and silica nanocomposite based on polyacrylamide on light and heavy oil recovery in presence of formation water using micromodel

Increasing world request for energy has made oil extraction from reservoirs more desirable.Many novel EOR methods have been proposed and utilized for this purpose.Using nanocomposites in chemical flooding is one of these novel methods.In this study,we investigated the impact of six injection solutions on the recovery of light and heavy oil with the presence of two different brines as formation water using a homogenous glass micromodel.All of the injection solutions were based on a 40,000 ppm Na Cl synthetic seawater(SSW),one of which was additive free and the others were prepared by dispersing nanocomposite silica-based polyacrylamide(NCSP),nanocomposite alumina-based polyacrylamide(NCAP),the combination of both nanocomposites silica and alumina based on polyacrylamide(NCSAP),surfactant(CTAB)and polyacrylamide(PAM)with a concentration of 1000 ppm as additives.The Stability of nanocomposites was tested against the salinity of the brine and temperature using salinity and DSC tests which were successful.Alongside stability tests,IFT,contact angle and oil recovery measurements were made.Visual results revealed that in addition to the effect of silica and alumina nanocomposite in reducing interfacial tension and wettability alteration,control of mobility ratio caused a major improvement in sweeping efficiency and oil recovery.According to the sweeping behavior of injected fluids,it was found that the main effect of surfactant was wettability alteration,for polyacrylamide was mobility control and for nanocomposites was the reduction of interfacial tension between oil and injected fluid,which was completely analyzed and checked out.Also,NCSAP with 95.83%and 70.33%and CTAB with 84.35%and 91%have the highest light oil recoveries at 250,000 ppm and 180,000 ppm salinity,respectively which is related to the superposition effect of interactions between nanocomposites,solution and oil.Based on our results it can be concluded that the most effective mechanism in oil recovery was IFT reduction which was done by CTAB reduction also by using a polymer-based nanocomposite such as NCSAP and adding the mobility control factor,the oil recovery can be further enhanced.In the case of heavy oil recovery,it can be concluded that the mobility control played a much more effective role when the PAM performed almost similarly to the CTAB and other nanocomposites with a recovery factor of around 17%.In this study,we tried to investigate the effect of different injection solutions and their related mechanisms on oil recovery.