Priscila F. Oliveira

Development and Evaluation of Solbrax-Water Nanoemulsions for Removal of Oil from Sand

In recent years, surfactants have been used to clean up soils and aquifers contaminated by petroleum and petroleum derivatives. The purpose of this study was to develop and evaluate nanoemulsions for remediation of soil contaminated by petroleum, by using a commercial solvent Solbrax. The nanoemulsions were prepared by the phase inversion temperature (PIT) method, using oil phase Solbrax (a solvent extracted from naphtha with low aromatics content) and a nonionic ethoxylated lauryl ether surfactant. The surfactant concentrations were varied from 10 to 12 wt% and the oil phase was varied from 5 to 20 wt%. A 23 factorial experimental design with center point run was used to evaluate the soil washing process, varying time, temperature, and shear rate of the system. The results show that the most efficient system (with 90% efficiency) was that using the nanoemulsion containing 5 wt% of Solbrax and 12 wt% of surfactant after four hours of washing, on 240 rotation·min−1 of shear rate and at a temperature of 318 K.

Comparison between coconut and curaua fibers chemically treated for compatibility with PP matrixes

Green coconut husk and curaua fibers were submitted to different chemical treatments—acid or alkaline followed by reaction with a silane compound—to improve compatibility between fiber and polypropylene (PP) matrix, in order to obtain composites with better properties than those of pure PP matrix for use as engineering materials. Fiber samples were analyzed before and after treatments to study the effects on thermal stability and morphology. The results showed that the crystallinity index and heat resistance significantly increased when the alkaline treatment followed by silane reaction was applied to both fibers. In this case, the crystallinity index increased from 53% in the coconut fiber in natura to 67% in the treated fiber. Regarding curaua fiber, the increase was from 61% to 81%. The degradation onset temperature of coconut fiber increased from 255℃ to 272℃ and of curaua fiber from 275℃ to 314℃. The treated fibers were mixed with a commercial PP matrix in a twin-screw mini-extruder at 180℃. The composites were analyzed by SEM to observe the compatibility between cellulose fibers and PP matrix.