Paulo Sérgio da Silva Porto

Electrocoagulation with polarity switch for fast oil removal from oil in water emulsions

An electrocoagulation technique using a 3.5 L reactor, with aluminum electrodes in a monopolar arrangement with polarity switch at each 10 s was used to separate oil from synthetic oily water similar in oil concentration to produced water from offshore platforms. Up to 98% of oil removal was achieved after 20 min of processing. Processing time dependence of the oil removal and pH was measured and successfully adjusted to exponential models, indicating a pseudo first order behavior. Statistical analysis was used to prove that electrical conductivity and total solids depend significantly on the concentration of electrolyte (NaCl) in the medium. Oil removal depends mostly on the distance between the electrodes but is proportional to electrolyte concentration when initial pH is 8. Electrocoagulation with polarity switch maximizes the lifetime of the electrodes. The process reduced oil concentration to a value below that stipulated by law, proving it can be an efficient technology to minimize the offshore drilling impact in the environment.

Applications of Fourier Transform Infrared and X-Ray Techniques to Analyze Nickel Ferrite Nanoparticles Produced

Various methods have been reported to obtain nanosized ferrite particles such as chemical coprecipitation, sol-gel, spray-drying, microwave plasma, sonochemical, hydrothermal synthesis, reverse micelle technique and mechano synthesis. In this work Nickel Ferrite nanoparticles are produced using coconut water or pectin extracted from apple peel (using sulfuric or chloridric acid) as precursor for the proteic sol-gel (PSG) method. The samples are prepared by drying and subsequent isothermal treatment of the sol gel at 873 or 1173 K during 2 hours. The resultant materials were analyzed by Fourier Transform Infrared Spectroscopy (FTIRS) and discussed with emphasis in the purity of the samples produced.

Investigation and Structural Characterization of Nickel Ferrite Nanoparticles Produced by Proteic Sol-Gel Method Using Two Kinds of Organic Precursors

Metallic oxide materials with AB2O4 structure are very interesting for technological applications. Nickel ferrite (NiFe2O4), for example, attracts considerable attention due to its chemical stability and mechanical hardness. These characteristics make it a suitable material for magnetic and magneto-optical applications. The properties of NiFe2O4 have a strong dependence on the crystallite size and microstructure. Due to this dependence, it is necessary to develop effective methods that allow controlling these variables. The aim of this work is to investigate the effect of time, temperature of isothermal treatment and choice of organic precursor during the production of NiFe2O4 samples employing the proteic sol-gel method have on crystallite size and microstructure. Two kinds of organic precursors were used: coconut water and pectin extracted from aple peel. Temperatures of 873 and 1173 K; 2, 4, 6, 8, 24 and 30 hours of isothermal treatment were also used. The samples produced were analyzed employing X-ray Diffraction.