Influência da segregação no desempenho de cinzas de casca de arroz como pozolanas e material adsorvente

Abstract

The main objective for the industry is to reduce the generation of wastes, or to find better uses to them, such as in the own productive process or as raw material in the elaboration of other materials. Also, a great amount of funds has been invested in researches for the transformation of such wastes, in by-products of commercial interest. In this way, the rice husk from the rice processing have been used as combustible, for producing energy. Rice husk ashes are generated from the rice husk burning, which presents a potential to be used as raw material in the production of several products in different industry sectors. Most of the works apply the rice husk ash in civil construction, because a great part of those ashes present pozzolanic characteristics as a result of their amorphous chemical structure and the high silica content. In fact, between other factors, the pozzolanicity of rice husk ash depends on the thermal process applied to the rice husk during burning. Researches have been demonstrating that the ashes also may be potentiality applied as adsorbent. However, the rice husk ash comes, many times, as a heterogeneous material so much in your particle size distribution as in your chemical composition. These characteristics can interfere in the applications limiting your use. The segregation of the wastes is thoroughly a technique applied in the administration of industrial solid waste and it can guarantee the recycle of the segregated materials. This work has as main objective to contribute for the valorization of the waste rice husk ash as coproduct through the segregation stage. It was studied the influence of the segregation of the rice husk ash, in physical-chemical characteristics, as well as your acting as pozzolanic and adsorbent. The samples and segregated fractions were characterized via physical (fire loss, specific gravity, specific surface area, particle size distribution), chemical (chemical analysis, X Ray diffraction) and microstructural parameters (scanning electronic microscopy with energy dispersion spectroscopy – EDS). The pozzolanic activity was determined after grinding the samples and the fractions via Cement pozzolanic and Electric Conductivity Methods. The adsorption rehearsals were accomplished with Cr(VI) solutions, that was quantified by the colorimeter method using 1,5-difenilcarbazida. Results demonstrated that the segregation became an important step, because removes impurities and contaminants from the samples and also originates fractions with different characteristics. It was observed, in pozzolanic activity, that the influence of the segregation links with the type of applied combustion process for the obtaining of the ash. It was observed, in adsorption rehearsals, that the segregation influenced in the removal of chromium (VI). Adsorption results showed, considering the experimental conditions in this work, the viability of the use of rice husk ash in the adsorption of chromium (VI) when adjusted the process’s parameters that guarantee the removal of chromium.