Regeneration of titanate nanotubes by Aspergillus niger and Penicillium sp . under static conditions

The adsorption of triphenylmethane dyes on the surface of nanostructured oxide materials has been successfully applied for the removal of dye from wastewater. Although this removal strategy does not generate harmful substances, the adsorption is not destructive and involves a phase transfer of pollutants to other secondary wastes. Due to these disadvantages, it is necessary to evaluate eco-friendly biological strategies to remove the adsorbed contaminants, to reuse them and to continue taking advantage of its adsorption capacity. Information concerning regeneration of nanostructured oxide material by biologic methods is currently unavailable. In the present study, the regeneration of titanate nanotubes (TNTs) was investigated and compared in the presence of two different fungal species: Aspergillus niger and Penicillium sp. Efficient regeneration of TNTs was achieved in the presence of both fungal species and no significant differences were observed. The adsorption capacity of the regenerated TNTs decreased by only 38 and 48% for A. niger and Penicillium sp., respectively. The UV–Vis, FTIR analysis, and TEM images confirmed the complete desorption of BF and the preservation of the tubular structure of TNTs. This study demonstrates that the regeneration of TNTs using biological activity could represent an efficient alternative over physico-chemical regeneration.