Copper-impregnated ceramic membranes and their anti-microbial effect against Escherichia coli

Abstract

In this work tubular commercial α alumina and mullite (M1 and M2, respectively) ceramic membranes were impregnated with copper nanoparticles and characterized aiming at their use in the disinfection of waters. Copper nanoparticles were obtained by the dissolution of Cu (NO3)2∙3H2O in a poly (vinyl alcohol) solution (PVA) 5% (m/v) followed by chemical reduction of the copper ions into metal particles by the use of sodium borohydride. The colloidal copper dispersion was impregnated into the commercial membranes by dip-coating and then the impregnated membranes were calci-nated at the temperature of 600°C for PVA removal. In order to assess the bactericidal efficiency of the prepared membranes microfiltration and inhibition tests were carried out using Escherichia coli as indicator microorganism. As a result, copper-containing membranes had bactericidal efficiencies, approximately, between 88.7 and >99.9%,and inhibition zone between 10 and 13 mm, approximately. On the other hand, copper less membranes resulted in low bacterial retention efficiencies, between 40.3 and 73.7%, and were devoid of any inhibition zone. The ceramic membranes without copper presented low efficiency due to their variation in pore size. The M1 membrane presented pores size between 0.1 and 3 µm, while the M2 membrane between 0.03 and 4 µm. According to the results, it was possible to confirm the importance of the presence of copper in the membranes. The results obtained in this work show that copper impregnation into tubular ceramic membranes was efficient and provided bactericidal effect.