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Ordered Ag-g-C 3 N 4 /SBA-15 was successfully synthesized using SBA-15 as a template and support. The samples were characterized by TEM, XRD, XPS, N 2 adsorption-desorption. The results showed that metallic silvers with diameter 15 nm were distributed on the surface of g-C 3 N 4 thin-layered. The specific surface area of the composite was 563.4 m 2 g −1 . As the final products for ozonation, oxalic acid was used to investigate its catalytic ability in heterogeneous photocatalytic ozonation under simulated solar light irradiation. Ordered Ag-g-C 3 N 4 /SBA-15 with the mass ratio of silver nitrate/dicyandiamide around 4% was found to be the most efficient for oxalic acid degradation. The kinetic constant was 1.60 and 2.52 times as high as that of solar light/Ag-g-C 3 N 4 /O 3 and solar light/g-C 3 N 4 /O 3 process, respectively. It demonstrated that both the Ag nanoparticles and improved specific surface area contributed to the enhancement, which promoted the decomposition of O 3 and increased the active sites in reaction. The synergy index for photocatalytic ozonation of oxalic acid was calculated to be 5.71, which indicated a superior synergistic effect between photocatalysis and ozonation. In addition, 4% Ag-g-C 3 N 4 /SBA-15 samples showed good stability in photocatalytic ozonation process by cycled for four times, and the mechanism was also confirmed in this study. It is suggested that Ag-g-C 3 N 4 /SBA-15 composites is a promising catalyst for the practical application of photocatalytic ozonation.

Ag-TiO 2 hollow micro-tube was successfully prepared using cotton fiber as template. It was used to photocatalytic ozonation of Atenolol (ATL) in present study (UV/Ag-TiO 2 /O 3 ). The results showed that 2% Ag-TiO 2 possessed the best catalytic performance for ATL mineralization and had a distinct advantage compared with bare TiO 2 . The variation of ozone concentration confirmed that Ag-TiO 2 hybrid not only increased the ozone amount in the solution, but also resulted in a fast decompose rate in the photocatalytic ozontion process. It meant that Ag act as a good photo-generated electron acceptor for photocatalysis and a beneficial decomposition center for ozone. Consequently, the synergistic effect of photocatalytic ozonation was enhanced and the mineralization of ATL was promoted. The recycle experiments proved that synthesized 2% Ag-TiO 2 micro-tube owned excellent stability in photocatalytic ozonation coupling system. In addition, the effect of pH value, doping amount of Ag on the ATL degradation was also investigated. It is indicated that 2% Ag-TiO 2 is an excellent catalyst for the photocatalytic ozonation of ATL.

Graphitic carbon nitride (g-C 3 N 4 )–reduced graphene oxide (rGO) nanocomposites were synthesized successfully by grinding a mixture of melamine and graphene oxide (GO) with different weight ratios, followed by calcination at 550 °C under flowing nitrogen atmosphere. Photoluminescence (PL) analysis was performed to investigate the efficiency of charge separation in g-C 3 N 4 –rGO composite. The result showed that the intensity of emission peak for g-C 3 N 4 –rGO composite is much lower than pure g-C 3 N 4 . The activity of g-C 3 N 4 –rGO composite in photocatalysis and photocatalytic ozonation process was evaluated by degradation of oxalic acid (OA) under simulated solar light irradiation. The results demonstrated that the degradation rate of OA with g-C 3 N 4 –rGO composite was significantly improved compared with pure g-C 3 N 4 in both process. This enhancement was due to the hetero-junction built between rGO and g-C 3 N 4 . Furthermore, during photocatalytic ozonation process, g-C 3 N 4 –rGO composite could trigger a synergistic effect between photocatalysis and ozonation. This study indicated that the metal-free g-C 3 N 4 –rGO nanocomposite showed high solar-light activity in photocatalytic ozonation process, which makes them promising materials for further applications in wastewater treatment.

A novel carbon black modified nano-TiO2 film photocatalyst (CB-TiO2) was prepared by a sol–gel method and used for degrading and mineralizing dibutyl phthalate. The film was characterized by XRD, SEM, and DRS techniques. Carbon black modification could make TiO2 film more pores, looser structure, smaller crystal sizes and longer excitation wavelength. The photocatalytic activity of the CB-TiO2 films was 1.4 times higher than that of TiO2 films in degrading dibutyl phthalate. The results showed that ozone concentrations had an important effect on degradation and mineralization of dibutyl phthalate. The combined photocatalysis with UV irradiation and ozonation (TiO2/UV/O3) process considerably improved mineralization and degradation of dibutyl phthalate compared to combined photocatalysis with UV irradiation (TiO2/UV) process, combined ozonation with UV irradiation (UV/O3) process and ozonation alone (O3) process. Dibutyl phthalate can be quickly mineralized in TiO2/UV/O3 and UV/O3, its mineralization followed pseudo-zero-order kinetics dependent upon ozone concentration and indicated its concentration did not affect the kinetics during TiO2/UV, UV/O3 and TiO2/UV/O3 processes. The kinetic study showed the mineralization rate constants of dibutyl phthalate with TiO2/UV/O3 are 1.2–1.8 times higher than that of UV/O3 with the same ozone concentration and 3.5 times higher than that of TiO2/UV.

Three processes combining different oxidations and subsequent biological activated carbon (BAC), i.e. O3-BAC, UV/O3-BAC and TiO2/UV/O3-BAC were employed to treat secondary effluents and compared. The effects of ozone dosage and empty bed contact time (EBCT) in BAC unit on dissolved organic carbon (DOC) removal were investigated. The results showed that the presence of UV and TiO2 improved ozone utilization and biodegradability of the effluent. DOC removal increased with ozone dosage and EBCT in BAC, however, 3 mg/L ozone dosage with 15 min oxidation time and 15 min EBCT in BAC were more economical and efficient. The synergetic effect between oxidation and BAC is in the order: TiO2/UV/O3-BAC > UV/O3-BAC > O3-BAC. Among three oxidation processes, organic pollutants with molecular weight (MW) 10,000 Da were mostly removed by O3 alone. GC–MS analysis showed dibutyl phthalate, bis(2-ethylhexyl) phthalate, 4-bromo-3-chloroaniline and other phenol derivatives were prevalent organic pollutants found in the secondary effluent. After TiO2/UV/O3 treatment, some aromatic compounds including 2,4-dichloro-benzenamine, 4-bromo-3-chloroaniline and 3,5-dimethoxy-acetophenone disappeared and some small molecules were formed, but the kinds and concentration of organic pollutants including phthalate esters were greatly reduced by the subsequent BAC unit.