| Summary: | This work reports the preliminary results of the development of composite self-assembling membranes obtained by the combination of reduced graphene oxide (rGO) with commercial Degussa P25 titanium dioxide (TiO<sub>2</sub>). The purpose is to demonstrate the possibility of combining, in the same self-standing material, the capability to treat wastewater containing both inorganic and organic pollutants by exploiting the established ability of rGO to capture metal ions together with that of TiO<sub>2</sub> to degrade organic substances. Moreover, this study also investigates the potential photocatalytic properties of tionite (TIO), to demonstrate the feasibility of replacing commercial TiO<sub>2</sub> with such waste-derived TiO<sub>2</sub>-containing material, fulfilling a circular economy approach. Thus, rGO–TiO<sub>2</sub> and rGO–TIO composite membranes, 1:1 by weight, were prepared and characterized by SEM-EDX, XRD, thermogravimetry, as well as by Raman and UV-Vis spectroscopies to verify the effective and homogeneous integration of the two components. Then, they were tested towards 3-mg L<sup>−1</sup> aqueous synthetic solutions of Fe<sup>3+</sup> and Cu<sup>2+</sup> ions to evaluate their metal adsorption ability, with values of the order of 0.1–0.2 mmol g<sub>membrane</sub><sup>−1</sup>, comparable or even slightly higher than those of pristine rGO. Finally, the ability of the composites to degrade a common organic pesticide, i.e., Imidacloprid<sup>®</sup>, was assessed in preliminary photocatalysis experiments, in which maximum degradation efficiencies of 25% (after 3 h) for rGO–TiO<sub>2</sub> and of 21% (after 1 h) for rGO–TIO were found. The result of tionite-containing membranes is particularly promising and worthy of further investigation, given that the anatase content of tionite is roughly 1/6 of the one in commercial TiO<sub>2</sub>.
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