Impregnação de carvão ativado de casca de coco de dendê (Elaeis guineensis) com zinco e cobre para inibição da formação de biofilme por Escherichia coli ATCC 8739

Abstract

Activated carbon is a carbonaceous material of high porosity and surface area, being one of the main materials used as adsorbent in water filters. However, microorganisms and organic matter can lodge on the surface and form biofilms that compromise their performance. Industrially, impregnated silver is used to hinder the development of microorganisms on the surface of the coal. In this context, the objective was to evaluate the impregnation of zinc and copper, less noble metals, on the activated carbon surface of Elaeis guineensis palm coconut shell and the impact on the inhibition of biofilm formation by Escherichia coli ATCC 8739. The impregnation was performed By heating with stirring, dryness and calcination in a muffle. The characterizations followed the methods recommended by the American Society of Testing and Materials (ASTM) as ash content, solubility, particle size and iodine number. The tests of metal leaching, biofilm formation and inhibition were carried out in fixed bed filter medium. Analyzes of the number of iodine showed that the surface of the activated carbon was not affected by the impregnation of the metals. It was found that the highest value of leached metal was 0.03% w/w for zinc and for copper the leaching values were below the limit of detection. The formation of biofilm by E. coli occurred on the surface of the activated carbon. Inhibition of biofilm formation was observed in samples impregnated with zinc and copper. Combined, metals gave inhibition of more than 6 logs in 24 h. Wherefore, in the present study it was demonstrated that the combination of zinc and copper metals on the activated carbon surface enhances the inhibition of biofilm formation by Escherichia coli ATCC 8739, providing an alternative in the control of bacterial colonization for the filter media industry.