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.
The aluminum monohydroxide pseudoboehmite is a common precursor for catalysts and ad/absorbents. Fibrillar pseudoboehmite powders were synthesized by the same preparation method from aqueous sols but aged in different times: 24, 48 and 168 hours. The sol particles were from fibrillar pseudoboehmite; the average length of the microfibrils changed sample to sample, the sizes increasing with the thermal aging time. The sols were dried by different methods: at room temperatures, forming a solid membrane; spray dried; dried at 60°C and 110°C from a gel from the sol aged 168 hours; all were fired between 200°C and 1000°C in oxidative atmosphere to produce activated transition aluminas. The phases formed was identified by XRD. The aim of the present paper is to present data showing that method of drying the sol has an effect on the temperature of formation of alpha-alumina due to the anisodiametric shape of the pseudoboehmite crystals.
Among the researches applied to the sustainable production of construction materials there are the incorporation of rejects from the civil construction to clayey masses to make bricks, tiles and other products of structural ceramics. Main objective of this paper is to show the results of these mixtures. Spherical samples had been conformed incorporating 1%, 5%, 10%, 20% and 30% of reject from the civil construction in mass. These samples had been evaluated on compressive strength after dried to 110°C and to color and compressive strength after burns to 950°C. The composition that presented better results had been conformed by extrusion in prismatic samples. Then, the dried to 110°C and burnt to 950°C samples had been evaluated on flexion strength and in linear retraction too. Industrial test was made having produced 1500 ceramic blocks that show similar or better properties of blocks without incorporation. It was measured the ceramic and leaching properties of the blocks. The mixture with 5% of rejects in the clayey mass show the better results in all tests.
A procedure that comes being studied for the exploitation of powder waste
rejected from the sanitary ware production is the incorporation in mass for red
ceramics. Objective of this work is to present the results gotten in the incorporation of
this rejects. The used clay was from ceramics industries of the Jundiai region, SP.
Spherical bodies test samples had been conformed incorporating 1%, 5%, 10%, 20%
and 30% of the powder waste in mass. These bodies had been evaluated on
compression resistance after dried to 110°C and to color after burns to 950°C. The
composition that presented better results had been conformed by extrusion in
prismatic bodies test samples. Again, the dried to 110°C and burnt to 950°C bodies
test samples had been evaluated on flexion resistance but to linear retraction too. It
was measured the ceramic properties of the burnt bodies test samples. Results indicate
that there is a great potential in the formula with 30% incorporation of powder waste
in mass. Comparative assays were made being used a mixture without incorporation
of the denominated white reject.
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