In this study, N-TiO2/O-doped N vacancy g-C3N4 was synthesized by the solvothermal method. The optimized photocatalyst N-TiO2/CNONV-2 has excellent photocatalytic activity, and it can reach about 3 times of tetracycline hydrochloride (TC−HCl) degradation rate and 41 times of Cr(VI) reduction rate comparing with N vacancy g-C3N4. Meanwhile, N-TiO2/CNONV-2 exhibited excellent photocatalytic activity and chemical stability under TC−HCl and Cr(VI) coexistence environment. The enhancement photocatalytic activity mechanism of N-TiO2/CNONV-2 is that Z-scheme heterojunctions accelerate the separation of electrons and holes, while mainly O2– and h+ attack TC−HCl and e– reduces Cr(VI) under TC−HCl and Cr(VI) coexistence environment. The influence of environmental factors (pH, organic matter, and inorganic salt) on the photocatalytic activity of N-TiO2/CNONV-2 under TC−HCl and Cr(VI) coexistence environment was studied. Furthermore, the toxicity of the intermediates was evaluated by quantitative structure-activity relationship (QSAR) prediction. The results demonstrated that the toxicity of TC intermediates can be degraded into low level over N-TiO2/CNONV-2.

Photocatalytic activity of N-TiO2/O-doped N vacancy g-C3N4 and the intermediates toxicity evaluation under tetracycline hydrochloride and Cr(VI) coexistence environment

In this work, an in-situ Fe-doped g-C3N4 catalyst was synthesized by thermal shrinkage polymerization. A heterogeneous photocatalysis-Fenton system was formed with the addition of H2O2 under visible irradiation and exhibited excellent and recyclable removal performance for refractory contaminants such as: phenol, bisphenol A, 2, 4-dichlorophenol and coking wastewater, which was due to the formation of σ-π bonds via Fe and N element in the triazine ring skeleton of Fe-g-C3N4. The electrons generated can be quickly transferred to Fe3+ to form Fe2+ under the interaction of the chemical bond. The efficiency of photoelectron separation was accelerated, and OH radicals were quickly generated with the reaction between Fe2+ and H2O2. Specifically, the recycling of Fe can be achieved in the heterogeneous system, which avoids the problems for the recycling and secondary pollution of Fe ions in homogeneous Fenton reaction. Parameters such as Fe doping amount, hydrogen peroxide concentration, pH value, catalyst concentration, and complex wastewater (coking wastewater) were optimized. The degradation of coking wastewater were also performed, and the chemical oxygen demand (COD) and total organic carbon (TOC) values for 300 ml coking wastewater could be reduced from 64.6 and 25.3 mg/L to 22.8 and 12.3 mg/L in 60 min, respectively. These results demonstrate photocatalysis-Fenton reaction with Fe-g-C3N4 catalyst is promising for environmental remediation.

In-situ Fe-doped g-C3N4 heterogeneous catalyst via photocatalysis-Fenton reaction with enriched photocatalytic performance for removal of complex wastewater

Visible light photocatalytic degradation of tetracycline over TiO2

Fabrication of novel magnetic MnFe2O4/bio-char composite and heterogeneous photo-Fenton degradation of tetracycline in near neutral pH.

Developing highly efficient photocatalysts for refractory pollutants degradation and hydrogen peroxide (H2O2) production is an ideal strategy to tackle environmental pollution and energy crisis. Herein, we synthesize a novel 2-hydroxy-4,6-dimethylpyrimidine (HDMP) grafted polymeric carbon nitride (CN) photocatalyst (ACN) by a facile in situ keto-enol cyclization method for addressing these issues. The photogenerated electrons and holes are migrated to HDMP and heptazine moiety, respectively. And the average decay lifetime of photogenerated charges of CN and ACN-10 is increased form (222 ± 23) to (289 ± 38) ps. Benefiting from the controllable electronic migration and accelerated intramolecular charge separation, the ACN photocatalyst exhibits a superior visible-light-driven photocatalytic activity for oxytetracycline degradation and H2O2 production. This work makes an insight into the intramolecular charge dynamics in CN, and presents a promising approach to the oxytetracycline degradation and H2O2 production.

Molecular engineering of polymeric carbon nitride for highly efficient photocatalytic oxytetracycline degradation and H2O2 production

Visible-light-driven removal of tetracycline antibiotics and reclamation of hydrogen energy from natural water matrices and wastewater by polymeric carbon nitride foam.

Huixiang Ang

Papers

Visible-light-driven removal of tetracycline antibiotics and reclamation of hydrogen energy from natural water matrices and wastewater by polymeric carbon nitride foam.