RESUMO
This article describes the impregnation of copper nanoparticles (CuNP) in a polyester fibre filter that can be used in solid-gas filtration to retain the spread of pathogen microorganisms in indoor environments. The impregnation of the CuNP was achieved by spraying the suspension on the surface of filter media. An acid pretreatment was also evaluated to increase the adhesion between fibre and nanoparticle. The synthesis of the CuNP was done by chemical reduction. The bacterial effect was measured through the contact method for Escherichia coli and Staphylococcus aureus, and we demonstrate that the presence of CuNP to filter media reduced up to 99.99% of gram-negative and 99.98% of gram-positive bacteria. The pretreatment with HCl was a good alternative to filter modification due to the higher adhesion between CuNP and the fibre while the high efficiency against pathogen microorganisms was kept. The modification of filters with CuNP can improve the air quality of indoor environments, vanishing the pathogen microorganisms circulating in the air.
RESUMO
The aim of this work was to characterize the coal fly ash from gasification process (G-CFA) and to analyze its potential as hexavalent chromium Cr (VI) adsorbent. The G-CFA was characterized in terms of physical, chemical, mineralogical, and morphological analyses. Bach adsorption studies were carried out in order to evaluate the influence of pH on the adsorption capacity and removal efficiency of Cr (VI). The G-CFA characterization demonstrated that the material possessed potential to be applied as an effective low-cost adsorbent, once it presents 18.82 m2 g-1, 0.036 cm3 g-1, and 7.56 nm of surface area, pore volume, and average pore diameter, respectively. The results also showed well-defined mineralogical phases and high content of siliceous material. The adsorption experiments demonstrated that the material has potential to be used as a chromium adsorbent with high removal efficiencies.