TiO2/fly ash novel substrate for simultaneous removal of heavy metals and surfactants

A novel, cost-effective substrate is obtained by hydrothermal processing from fly ash (CPH - Brasov, Romania) coated with a wide band gap semiconductor, TiO2. The new substrate is used removing, in a single step process, heavy metals (Cd2+ and Cu2+) and surfactants (1-hexadecyltrimetylammonium bromide - HTAB and dodecylbenzenesulfonate - SDBS) from synthetic wastewaters containing two (heavy metal + surfactant) and three pollutants (two heavy metals + one surfactant). The substrate proves to be highly efficient in heavy metals adsorption and the TiO2 layer on the fly ash grain support demonstrates a good activity in surfactants photodegradation. The adsorption kinetic and mechanisms, and the substrate capacities are further discussed correlated with the surface structure (XRD), composition (EDS, FTIR), and morphology (SEM, AFM). The results indicate parallel adsorption of heavy metals and surfactants from mixed solutions and show that, the fly ash - TiO2 substrate, allows efficient simultaneous removal of heavy metals and surfactant, resulting waters that respect the discharge regulations. (C) 2013 Elsevier B.V. All rights reserved.