Search

• Carbon doped TiO 2 /kaolinite composite was rationally designed and assembled. • The composite's reaction rate constant is about 25 times higher than that of pure TiO 2. • TiIII defects and localized occupied states are responsible for performance enhancement. • Kaolinite induced carrier effect plays important role in catalytic activity enhancement. • The composite material might be a promising candidate for degrading trace amounts of pollutants. In this work, kaolinite supported monodispersed TiO 2 with carbon regulation was prepared through rational design and different dimensions' assembly, leading to generation of TiIII species in carbon doped TiO 2 /kaolinite (C-TiO 2 /kaolinite) composite. The C-TiO 2 /kaolinite composite exhibited improved degradation performance towards ciprofloxacin under visible light, with a reaction rate constant of 0.00597 min−1, which is about 3.24 and 24.88 times higher than that of 2.0C-T (2.0% carbon-doped TiO 2) and pure TiO 2 , respectively. Based on various materials characterization methods and DFT calculations, it was indicated that the electronic structure was correlated with the changes in light absorption, charge carrier lifetime, and reactive oxygen species (ROS). The enhanced visible light responding ability could be attributed to the synergistic effect between natural kaolinite and nanosized TiO 2 , the formation of localized occupied states in the gap, and the formation of TiIII defects consisted of surface oxygen vacancies. All of them effectively increase the separation efficiency, migration velocity, and lifetime of the photoinduced charge carriers under visible-light irradiation. Overall, our study provides a promising candidate for effective degradation of trace amounts of pharmaceutical and personal care products and other highly toxic contaminants with the assistance of solar light. [ABSTRACT FROM AUTHOR]

• Diatomite and CoFe 2 O 4 was effectively assembled to activate peroxymonosulfate. • CoFe 2 O 4 /diatomite catalyst has lower metal dissolution rate. • Surface structure and crystallization dispersion improve activation performance. • The 1O 2 was the primary active substance for BPA degradation. • Weak basic condition enhanced PMS activation and increased BPA degradation. Porous magnetic CoFe 2 O 4 /diatomite catalyst (CFD) was rationally synthesized via a facile citrate combustion process. The relationship between catalytic performance and material properties of the prepared catalysts was comprehensively investigated by various characterizations, especially for the interface interaction between CoFe 2 O 4 and diatomite as well as crystallization regulation of CoFe 2 O 4. Overall, higher specific surface area, overspreading surface hydroxyl groups, better crystal dispersion and abundant surface-active sites make CFD have better degradation performance of bisphenol A (BPA) than pure CoFe 2 O 4 in the presence of peroxymonosulfate (PMS), and the pseudo-first-order reaction rate constant of 40-CFD (40% CoFe 2 O 4 /diatomite) is almost 5.32 times higher than that of pure CoFe 2 O 4. Besides, CFD has excellent magnetic properties, lower metal dissolution rate and good reusability. In addition, electron paramagnetic resonance (EPR) and radical quenching experiments show that sulfate radicals (SO 4 −) and singlet oxygen radicals (1O 2) generated from the electron transfer of BPA molecule and valence state change of transition metals should be the predominant oxidation species. Moreover, possible degradation pathways of BPA are determined by the detection of intermediates derived from the results of liquid chromatograph–mass spectrometer (LC–MS). In brief, it is indicated that the CoFe 2 O 4 /diatomite composite material is an efficient and environmentally friendly catalyst, which has a great potential application in wastewater treatment by activating PMS. [ABSTRACT FROM AUTHOR]