BackgroundIt is imperative to eliminate bacteria present in water in order to avoid problems in healthy. Escherichia coli and Salmonella typhi bacteria are two common pollutants and they are developing resistance to some of the most used bactericide. Therefore new biocide materials are being tested. Thus, gold nanoparticles are proposed to inhibit the growth of these two microorganisms.ResultsGold nanoparticles were supported onto clinoptilolite, mordenite and faujasite zeolites. Content of gold in materials varied between 2.3 and 2.8 wt%. The size, dispersion and roughness of gold nanoparticles were highly dependent of the zeolite support. The faujasite support was the support where the 5 nm nanoparticles were highly dispersed. The efficiency of gold-zeolites as bactericides of Escherichia coli and Salmonella typhi was determined by the zeolite support.ConclusionsGold nanoparticles dispersed on zeolites eliminate Escherichia coli and Salmonella typhi at short times. The biocidal properties of gold nanoparticles are influenced by the type of support which, indeed, drives key parameters as the size and roughness of nanoparticles. The more actives materials were pointed out Au-faujasite. These materials contained particles sized 5 nm at surface and eliminate 90–95% of Escherichia coli and Salmonella typhi colonies.
Lithium-sodium metazirconate solid solutions, Li 2-x Na x ZrO 3 , were tested as CO 2 captors. The thermal analyses of these materials showed that all the solid solutions present similar behaviors under air and N 2 . The samples lost weight due to two different processes, desorption of physisorbed water (∼100 °C) and a decarbonation process (400-700 °C). In fact, the quantities of water and CO 2 desorbed increased as a function of the sodium content. Thermal analyses into a CO 2 flux showed that Li 2-x Na x Zr 2 O 7 solid solutions present a high CO 2 absorption. The solid solutions absorb CO 2 between 400 and 600 °C, but samples containing the sodium phase absorbed CO 2 in two distinct steps. First, at low temperatures, there is a CO 2 chemisorption, only at the surface of the particles, forming a carbonate shell. Later, when the temperature reaches 400 °C, or more, a second absorption process takes place. In this process lithium and/or sodium atoms diffuse from the core of the particles to the surface, through an external carbonate shell. The differences observed in the CO 2 sorption processes were explained with thermodynamic data.
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