Dye wastewater due to industrialization, urbanization and academic activities has become one of the most important environmental issues today. Photocatalytic degradation technology is considered as a promising technology for treating dye wastewater due to its advantages of environmental protection and low energy consumption. Herein, titanium dioxide–reduced graphene oxide composites (TiO₂-RGO) were prepared by a one-step hydrothermal method to degrade different dyes (methyl orange, methylene blue and rhodamine B) in water. The structure and morphology of TiO₂-RGO were characterized using various technical approaches. The degradation effect of TiO₂-RGO on the dye was in accordance with a first-order kinetic reaction. The degradation rate of TiO₂-6%RGO for methyl orange at 15 min was 1.67 times higher than that of TiO₂, due to the strong electron transport ability and excellent adsorption properties of graphene. TiO₂-6%RGO has better degradation performance for fluorescent dyes and anionic azo dyes. Notably, the degradation rate of methyl orange by TiO₂-6%RGO photocatalysis for 90 min could reach 96.9%. Meanwhile, the TiO₂-6%RGO showed excellent reusability, as the initial degradation rate of 93.2% was maintained after five degradation cycles of methyl orange solution. The present work provides a universal strategy for designing efficient photocatalytic materials.

Oil-polluted water has become one of the most important environmental concerns nowadays due to the increasing industrial oily wastewater and frequent oil spill accidents. Herein, a novel two-dimensional (2D) nano-mica sheets assembled composite membrane with underwater super-oleophobic properties was developed for effective oil/water separation. A 2D nano-mica sheet was synthesized by a facile solvent-assisted ultrasonic exfoliation and then the obtained 2D nano-mica sheets were co-deposited with dopamine on polyvinylidene fluoride substrate to prepare nano-mica composite membranes (NCM). The NCM is hydrophilic in air and super-oleophobic underwater (the water contact angle in the air is 37.6°, and the oil contact angle in water is 151.4°). Furthermore, the prepared NCM provided outstanding stability in different acid–base environments (pH = 1–11). Noteworthily, the oil removal rate is higher than 99.5% as the sodium dodecyl sulfate SDS-stabilized oil (soya-bean oil, mineral oil and pump oil) -in-water emulsions. Meanwhile, the NCM showed excellent reusability, as the oil removal efficiency kept at 99.0% after ten soya-bean oil-in-water or mineral oil-in-water emulsion filtration cycles. The present work paved a new way for developing a low-cost and environmentally friendly strategy for oily wastewater treatment and developed a high-increment utilization application field for natural minerals.