Preparação e caracterização de membranas impregnadas com nanopartículas de prata e cobre e sua aplicação na desinfecção da água

Abstract

The contamination and the improper use of water linked to the population growth have caused concern on the part of the legislation, which has been leading to the study of new technologies that aim the treatment, reuse and quality recovery of water. Due to the low cost and the high efficiency, the technology with membranes has dominated the water purification market. The use of membranes combined with antibacterial agents (e.g. silver and copper) has been highlighted. In this work, commercial tubular ceramic membranes, α alumina and mullite (M1 and M2 respectively), impregnated with silver and copper nanoparticles were prepared and characterized in order to be applied in water disinfection. The commercial membranes were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Mercury Intrusion Porosimetry (MIP) and tests of permeability and of protein retention. The silver and copper nanoparticles were obtained by dissolving AgNO3 and Cu(NO3)2∙3H2O, respectively, in poly(vinyl alcohol) (PVA) 5% (w/v) followed by the chemical reduction of silver and copper ions into metallic particles. Those colloidal dispersions obtained were impregnated in the commercial membranes by dip-coating and then, were calcined at 600 ° C to remove the PVA. To evaluate the bactericidal efficiency of the prepared membranes, tests of microfiltration and of zone of inhibition were performed using Escherichia coli as the microorganism indicator. As results, both silver and copper membranes showed bactericidal efficiencies between 88.75 and 100% and an inhibition zone between 10 and 15 mm. On the other hand, the membranes without silver and copper impregnation showed low efficiency of bacteria retention, between 40.32 and 73.78% and did not presented a zone of inhibition. The results of this study indicates that the impregnation of silver and copper in tubular ceramic membranes was efficient and provided bactericidal effect.[resumo fornecido pelo autor]