E. L. Barros Neto

Heavy metals extraction by microemulsions.

The objective of this study is the heavy metal extraction by microemulsion, using regional vegetable oils as surfactants. Firstly, the main parameters, which have influence in the microemulsion region, such as: nature of cosurfactant, influence of cosurfactant (C)/surfactant (S) ratio and salinity were studied, with the objective of choosing the best extraction system. The extraction/reextraction process by microemulsion consists of two stages. In the first one, the heavy metal ion present in the aqueous phase is extracted by the microemulsion. In a second step, the reextraction process occurs: the microemulsion phase, rich in metal, is acidified and the metal is recovered in a new aqueous phase, with higher concentration. The used system had the following parameters: surfactant-saponified coconut oil; cosurfactant-n-butanol; oil phase-kerosene; C/S ratio=4; salinity-2% (NaCl); temperature of 27+/-1 degrees C; water phase-aqueous solution that varied according to the heavy metal in study (Cr, Cu, Fe, Mn, Ni and Pb). A methodology of experimental planning was used (Scheffé Net) to study the behavior of the extraction in a chosen domain. The extraction was accomplished in one step and yielded extraction percentage higher than 98% for all metals. In the reextraction HCl-8M was used as reextraction agent and the influence of the pH and time were verified. This work showed the great efficiency of the microemulsion, indicating that it is possible to extract selectively the heavy metals from the aqueous phase.

Rheological properties of a new surfactant-based fracturing gel

Surfactant-based fracturing gels are considered as clean gels due to the absence of insoluble residues in their composition. This kind of fluid has been developed to minimize or eliminate damages to fractures. Therefore, new studies about gel rheological properties become more and more important, namely viscosity, the most important property of fracturing gels. This research was accomplished with the purpose of evaluating a new anionic surfactant-based gel. Steady and oscillatory shear experiments were carried out in order to evaluate the inner structure of the developed gel with variable composition, within the gel region in a pseudoternary diagram. It could be observed that small variations in gel composition resulted in changes in micellar structure.

Alternative fuels composed by blends of nonionic surfactant with diesel and water: engine performance and emissions

Diesel - based microemulsions and a surfactant/diesel blend, using ethoxylated (5 EO) nonylphenol as surfactant, were prepared and tested in a diesel engine to evaluate its performance and emissions. The following properties were evaluated: density, viscosity, cloud point and corrosiveness. Experimental results showed that density and viscosity were greater than those obtained for neat diesel. Cloud point and corrosiveness were not affected by water and surfactant. Specific fuel consumption of the microemulsion systems was greater than that of diesel, but the small droplets of water improved diesel combustion. Compared with diesel, an increase in carbon monoxide (CO) and nitrogen oxide (NOx) emissions and a decrease in black smoke emissions were obtained. In general, only microemulsions with up to 6% water are in accord with Brazilian diesel/biodiesel fuel regulations and specifications.

Application of Surfactants for Obtaining Hydraulic Fracturing Gel

Abstract Insoluble residues left in fractures by fracturing fluids have been the object of study by many authors, since these residues cause damage in reservoirs. The objective of this research was the development of a novel surfactant-based fracturing gel with the purpose of minimizing or eliminating the damage in the fracture. A comparison between the properties of a surfactant-based gel and a crosslinked hydroxypropylguar (HPG) fluid was made. Through rheological tests, fluid loss and setting rate, one can conclude that the obtained gel presents compatible characteristics when compared with the HPG gel.

Incorporation of bentonite clay in cassava starch films for the reduction of water vapor permeability

Complete factorial planning 23 was applied to identify the influence of the cassava starch(A), glycerol(B) and modified clay(C) content on the water vapor permeability(WVP) of the cassava starch films with the addition of bentonite clay as a filler, its surface was modified by ion exchange from cetyltrimethyl ammonium bromide. The films were characterized by X-ray diffraction(XRD), fourier transform by infrared radiation(FTIR), atomic force microscopy(AFM) and scanning electron microscopy(SEM). The factorial analysis suggested a mathematical model thats predicting the optimal condition of the minimization of WVP. The influence of each individual factor and interaction in the WVP was investigated by Pareto graph, response surface and the optimization was established by the desirability function. The sequence of the degree of statistical significance of the investigated effects on the WVP observed in the Pareto graph was C>B>A>BC>AC. Interactions AB, BC and AC showed that the modified clay was the factor of greater significance.

Enhanced Oil Recovery and Adsorption of Ionic Surfactant

In this work, three ionic surfactants (F, G, and H) were evaluated in surfactant adsorption experiment and oil recovery tests. Both sets of tests were carried out in a surfactant flooding apparatus, using 30 psi as pressure gradient. The concentration of the solutions injected in adsorption and recovery tests were 30–80% above the critical micelle concentration, to ensure micelle formation. The results obtained showed that adsorption was higher for G (2.7 g.L−1) and the better oil recovery was for G (89.0%).

Oil Recovery Performance of Surfactant Solutions and Adsorption in Sandstone

Abstract In this article, five nonionic surfactants with different ethoxylation degrees (R70, R95, R120, R150, and R200) were evaluated in surfactant adsorption experiments and oil recovery tests. Both sets of tests were carried out in a surfactant flooding apparatus using 30 psi as pressure gradient. The concentration of the solutions injected in adsorption tests were 30% above the critical micelle concentration (c.m.c.) to ensure micelle formation. In oil recovery tests, the solution concentration varied from the c.m.c. until 500% above it. The results obtained showed that adsorption was higher for R120 and the better oil recovery was for R200.

Study of Influence of Replacement Waste Oil Well Drilling Fluid in the Standard Mass of a Ceramic Industry in São Gonçalo do Amarante/RN, Brazil

The properties of ceramic materials can be greatly influenced when a residue is added to its composition. This article aims to study the incorporation of waste oil well drilling fluid in the standard bulk for fabrication of red ceramic. The success of the merger can reduce costs in the production of ceramic pieces and reduce the environmental impacts caused by waste. The results reveals that the use of the residue for the manufacture of the ceramic products is possible (tiles, massive bricks and hollow bricks) replacing clay up to 40%, according the requirements of the norm and in the literature for the technological properties of the final product.