Marilda M.G. Ramos Vianna

Brazilian organoclays as nanostructured sorbents of petroleum-derived hydrocarbons

Organophilic clays were prepared using a bentonite from the town of Boa Vista, state of Paraiba, Brazil, and a quaternary ammonium salt (Genamin CTAC-50). The materials obtained were characterized by X-ray diffraction and infrared spectroscopy. The results showed a good gasoline, toluene, diesel fuel and kerosene adsorbing capacity.

Synthesis and characterization of modified clays as sorbents of toluene and xylene

Benzene, toluene, ethylbenzene, and the xylenes (BTEX) are the major water-soluble constituents of gasoline that may contaminate soils and natural waters, which can be sorbed by organoclays. This study investigates the sorption of toluene and xylene by organoclays produced from Brazilian bentonite (SVC) and from Wyoming bentonite (SSA) with hexadecyltrimethylammonium (HDTMA), as well as by a commercial organoclay (SCo). The organoclays were characterized by X-Ray Diffraction, Differential Thermal Analysis, Thermogravimetry. Isothermal sorption were performed. The efficiencies of the organoclays on removing toluene increased in the order: SVC-HDTMA < SSA-HDTMA < SCo. The xylene sorption by SVC-HDTMA and SSA-HDTMA organoclays was about two times higher than by the SCo. These organoclays may be used as permeable reactive barriers or in ceramic filters for petroleum waste-water treatment systems.

Study of the Mechanical Performance of Composites of Rubber Powder and Cement

The wastes generated indirectly by the tire industry have shown the necessity of the study of news treatments to those wastes. The tire after its utilization by the consumer has no application and consequently it has to be discharged inasmuch as it can not be reused totally. This work studies the addition of the rubber to Portland cement. The study realized the characterization of the rubber powder by granulometric analysis and of the composite samples (compressive strength, porosity, impact strength and density analysis). For those analysis samples were molded with Portland cement, water and rubber powder. Samples were prepared containing from 10 to 30% of rubber and a range of 30 at 80% of water, with respect to dry cement. The samples that showed good strength to impact were submitted at compressive strength, porosity and density analysis. The results obtained were: compressive strength with a range of 6 at 32 MPa, porosity 19,0 and 22,8%, related to water absorption method and density with a range of 1,63 at 1,82x10 3 kg/m 3 . Concrete containing rubber powder has potential use in solids blocks at civil construction.