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Structural shifts associated with functional dynamics in a bacterial community may provide clues for identifying the most valuable members in an ecosystem. A laboratory-scale denitrifying reactor was adapted from use of non-efficient seeding sludge and was utilized to degrade quinoline and remove the chemical oxygen demand. Stable removal efficiencies were achieved after an adaptation period of six weeks. Both denaturing gradient gel electrophoresis profiling of the 16S rRNA gene V3 region and comparison of the 16S rRNA gene sequence clone libraries (LIBSHUFF analysis) demonstrated that microbial communities in the denitrifying reactor and seeding sludge were significantly distinct. The percentage of the clones affiliated with the genera Thauera and Azoarcus was 74% in the denitrifying reactor and 4% in the seeding sludge. Real-time quantitative PCR also indicated that species of the genera Thauera and Azoarcus increased in abundance by about one order of magnitude during the period of adaptation. The greater abundance of Thauera and Azoarcus in association with higher efficiency after adaptation suggested that these phylotypes might play an important role for quinoline and chemical oxygen demand removal under denitrifying conditions.

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Well dispersed TiO2 nanocrystals with (001) facets were successfully grown in situ on g-C3N4 through a facial solvothermal method. The resultant TiO2/g-C3N4 composites exhibit remarkably higher efficiency for photocatalytic degradation of phenol as compared to pure catalysts (g-C3N4 or TiO2) or mechanically mixed TiO2/g-C3N4. The optimal composite with 11.2 wt% TiO2 showed the highest degradation rate constant, which is 2.8 times that of pure g-C3N4, 2.2 times that of pure TiO2, and 1.4 times that of mechanically mixed TiO2/g-C3N4. The enhanced photocatalytic activity is mainly attributed to the effective charge separation derived from two aspects: (1) well matched energy levels between TiO2 and g-C3N4 and (2) a uniform and close contact between TiO2 and g-C3N4 that resulted from the in situ growth of highly dispersed TiO2 nanocrystals. The TiO2/g-C3N4 hybrid material prepared in this study is expected to provide a good foundation for the further design and synthesis of advanced TiO2/g-C3N4-based functional materials, and the in situ growth method developed is hopeful to provide a new strategy for the synthesis of other semiconductor-modified g-C3N4 materials.

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In the field of green chemistry, producing hydrogen peroxide (H 2 O 2 ) via photocatalysis could be a promising method for obtaining chemical feedstock during industrial and environmental processes. Herein, we simultaneously introduced inverse opal (IO) structure and carbon vacancies (CVs) into carbon nitride to improve H 2 O 2 production by photocatalysis. Experimental results reveal that, after visible light irradiation for 2 h, IO carbon nitride (IO CN-Cv) shows a H 2 O 2 generation value of 325.74 μM over 1.69, 2.13, and 1.84 times more than the H 2 O 2 generation of bulk CN-Cvs (bulk carbon nitride with Cvs), bulk CN (bulk carbon nitride without Cvs), and nanosheet CN (carbon nitride nanosheet), respectively. On the one hand, the typical IO structure improves the efficiency of visible light absorption and simultaneously provides more surface area for the adsorption of molecular oxygen. Meanwhile, the introduction of Cvs improves the separation ability of carriers. This study offers a new idea for enhanced production of H 2 O 2 using visible light with metal-free materials in the era of energy shortage.