Combination of photoelectrocatalysis and adsorption for removal of bisphenol A over TiO2-graphene hydrogel with 3D network structure

We successfully fabricated the three-dimensional (3D) hydrogel of titanium dioxide (TiO2)-graphene using a simple one-pot method and exhibited enriched adsorption-photoelectrocatalytic degradation ability of low concentration bisphenol A (BPA). Combined with the unique adsorption of graphene hydrogel and the effective photoelectrocatalytic performance of TiO2, we rapidly enriched the organic pollutants and conducted efficient in situ degradation. The low-concentration BPA (20 mg/L) was degraded completely by the TiO2-rGH electrode in 5 h through the synergistic effect of adsorption-photoelectrocatalytic. The photogenerated charge on the surface of TiO2 is rapidly separated by the action of the applied electric field and the graphene sheet. The high conductivity of the graphene makes the TiO2-graphene hydrogel rapidly conducting the charge and solves the problem of poor conductivity of the semiconductor electrode. On the basis of these advantages, the TiO2-rGH has a cross-porous network structure that favors the anchor of more TiO2 nanocrystals, the specific surface area and reactive sites are greater than the thin film electrode, and the structure is conducive to significantly improving the BPA removal efficiency. By contrast, the BPA degradation of TiO2-rGO thin film electrode was 40% after 4 h of ultraviolet irradiation, whereas the removal rate of BPA over the same mass of TiO2-rGH electrode rate was up to 96%. At the same time, the TiO2-rGH electrode without filtering can be achieved quickly separated from the recovery due to its special macro-3D network structure. Its removal ability still maintains above 90% after 10 times cyclic experiments with self-regeneration characteristics. It can be achieved rapid separation and recovery without filtering.