Analysis of Pollution in Dianchi Lake and Consideration of Its Application in Crop Planting

AbstractAfter investigating the distribution and composition of N-cycle-related bacteria of different sites and different depth of Dianchi sediment, we analyzed the longitudinal distribution, lateral distribution of N, its transportation and transformation in Dianchi sediment, as well as the involvement of these bacteria in nitrogen cycle. Conclusion was drawn as follows, (1) Azotobateria could be effectively used as indicative strains to track the changes of Dianchi pollution because the distribution of Azotobateria can not only indicate N contamination but also P enrichment, (2) ammoniate and nitrite is mainly existed in top sediment of Dianchi Lake while other forms of nitrogen mainly in deeper sediment, (3) due to the fact that Dianchi is rich in P, together with the mutual promotion between N pollution and P pollution, the pollution of south part will worsen rapidly, (4) if the south part is also polluted badly, the pollution distribution will appear as peaking at both ends (north and south), and the pollution will definitely extend toward the middle, and finally Dianchi Lake will totally be seriously polluted. Combining with the fact that 40% of Dianchi pollution was caused by abusive use of chemical fertilizer, we put forward the idea of “changing pollutants into things of value”, which could be specified as “using the sediment as agricultural fertilizer”. Such method can solve the problem of internal pollution, and what's more, it can develop agriculture, while cut down the use of chemical fertilizer and thus reduce relative pollution source

Impact of the COVID-19 lockdown on air pollution in an industrial city in Northeastern China

Many studies in China investigated how the lockdown following the coronavirus disease 2019 substantially affected air quality; however, few were conducted in Northeastern China. Here, the changes in six criteria air pollutants, including particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2), and ozone (O3), were investigated in Shenyang from January to May 2015–2020. Compared with the pre-lockdown, the mass concentrations of PM2.5, PM10, SO2, NO2, and CO during the lockdown decreased by 40.3% to 48.6%, indicating a positive impact of lockdown policies on reducing pollutant emissions. The responses of PM2.5, PM10, and CO to the lockdown measures in downtown areas were more sensitive than in the suburbs. However, the O3 concentration showed the opposite trend, attributed to the drop in NOx and particulate matters. Compared to the same period in 2015–2019, the proportion of days with good air quality increased from 63.2% to 77.2% during the lockdown and Shenyang experienced no severe pollution. Our results suggest that reducing human activities can improve air quality; however, coordinated control policies of O3, PM2.5, and NO2 are imperative.

Preparation and Photocatalytic Activities of TiO₂-Based Composite Catalysts

While modern industry has contributed to the prosperity of an increasingly urbanized society, it has also led to serious pollution problems, with discharged wastewater and exhaust gases causing significant environmental harm. Titanium dioxide (TiO2), which is an excellent photocatalyst, has received extensive attention because it is inexpensive and able to photocatalytically degrade pollutants in an environmentally friendly manner. TiO2 has many advantages, including high chemical stability, low toxicity, low operating costs, and environmental friendliness. TiO2 is an N-order semiconductor material with a bandgap of 3.2 eV. Only when the wavelength of ultraviolet light is less than or equal to 387.5 nm, the valence band electrons can obtain the energy of the photon and pass through the conduction band to form photoelectrons, meanwhile the valence band forms a photogenerated hole. And light in other wavelength regions does not excite this photogenerated electrons. The most common methods used to improve the photocatalytic efficiency of TiO2 involve increasing its photoresponse range and reducing photogenerated-carrier coupling. The morphology, size, and structure of a heterojunction can be altered through element doping, leading to improved photocatalytic efficiency. Mainstream methods for preparing TiO2 are reviewed in this paper, with several excellent preparation schemes for improving the photocatalytic efficiency of TiO2 introduced. TiO2 is mainly prepared using sol-gel, solvothermal, hydrothermal, anodic oxidation, microwave-assisted, CVD and PVD methods, and TiO2 nanoparticles with excellent photocatalytic properties can also be prepared. Ti-containing materials are widely used to purify harmful gases, as well as contaminants from building materials, coatings, and daily necessities. Therefore, the preparation and applications of titanium materials have become globally popular research topics

Preparation of Fenton Catalysts for Water Treatment

In the heterogeneous Fenton reaction, a solid catalyst reacts with H2O2 to generate highly oxidizing free radicals, that degrade organic pollutants in aqueous solutions. In this study, impregnation calcination was used to modify activated carbon and load it with various metal compounds. The synergistic catalysis of the various metal compounds showed improved catalytic activity, and the prepared heterogeneous Fenton catalyst exhibited high catalytic activity, a wide pH range, and good stability. The concentration ratios of the Fenton catalyst impregnation solutions-were as follows: Fe3+, Cu2+, Mn2+, and Ce3+ at 0.45, 0.72, 0.19, and 0.11 mol/L, respectively. The optimal sintering temperature of AC impregnation was determined through TGA/DSC, SEM, SEM-EDS, XPS, and XRD testing. At a final calcination temperature of 900 °C, the degradation efficiency of 10 ppm methylene blue reached 98.25% at pH 5 with 5 mM H2O2. After ten soaking cycles, the degradation efficiency exceeded 90%. The structure and performance of the catalysts were characterized using EPR, BET, ICP, and UV spectroscopy, demonstrating the excellent performance of the catalyst and providing an improved treatment plan for solving wastewater problems

Synthesis and Photoelectrocatalytic Applications of TiO2/ZnO/Diatomite Composites

ZnO and TiO2 are semiconductor nanomaterials that are widely used in photocatalysis. However, the relatively high recombination rate and low quantum yield of photogenerated electron–hole pairs limit their practical applications. In this study, a series of TiO2/ZnO/diatomite composites with various compositions were successfully prepared via a two-step precipitation method. They exhibited stronger UV–visible absorption properties and substantially lower fluorescence intensities than those of ZnO and ZnO/diatomite, which was mainly due to the low recombination rate of the photogenerated electron–hole pairs in the composite system. The reaction intermediates of methylene blue were detected by liquid chromatography–mass spectrometry, and the degradation process was determined. The best composite catalyst was used for the degradation of gaseous methylbenzene and gaseous acetone. The gaseous acetone degradation product was determined to be acetaldehyde via gas chromatography–mass spectrometry. The results show that the composite catalyst exhibited a good photocatalytic degradation of both liquid pollutants and harmful volatile gases. When applied to the hydrogen and oxygen evolution reactions, the composite catalyst retained a good photoresponsivity and electrolytic efficiency

Synthesis and Photoelectrocatalytic Applications of TiO₂/ZnO/Diatomite Composites

ZnO and TiO2 are semiconductor nanomaterials that are widely used in photocatalysis. However, the relatively high recombination rate and low quantum yield of photogenerated electron–hole pairs limit their practical applications. In this study, a series of TiO2/ZnO/diatomite composites with various compositions were successfully prepared via a two-step precipitation method. They exhibited stronger UV–visible absorption properties and substantially lower fluorescence intensities than those of ZnO and ZnO/diatomite, which was mainly due to the low recombination rate of the photogenerated electron–hole pairs in the composite system. The reaction intermediates of methylene blue were detected by liquid chromatography–mass spectrometry, and the degradation process was determined. The best composite catalyst was used for the degradation of gaseous methylbenzene and gaseous acetone. The gaseous acetone degradation product was determined to be acetaldehyde via gas chromatography–mass spectrometry. The results show that the composite catalyst exhibited a good photocatalytic degradation of both liquid pollutants and harmful volatile gases. When applied to the hydrogen and oxygen evolution reactions, the composite catalyst retained a good photoresponsivity and electrolytic efficiency

Numerical modeling of the gasification based biomass co-firing in a 600Â MW pulverized coal boiler

Gasification based biomass co-firing was an attractive technology for biomass utilization. Compared to directly co-firing of biomass and coal, it might: (1) avoid feeding biomass into boiler, (2) reduce boiler fouling and corrosion problem, and (3) avoid altering ash characteristics. In this paper, CFD modeling of product gas (from biomass gasification) and coal co-firing in a 600 MW tangential PC boiler was carried out. The results showed that NOx emission was reduced about 50-70% when the product gas was injected through the lowest layer burner. The fouling problem can be reduced with furnace temperature decreasing for co-firing case. The convection heat transfer area should be increased or the co-firing ratio of product gas should be decreased to keep boiler rated capacity.Biomass Coal Co-firing Nitric oxide (NO)

Highly Efficient Photo-Degradation of Gaseous Organic Pollutants Catalyzed by Diatomite-Supported Titanium Dioxide

Volatile organic compounds (VOCs) are the most harmful contaminants that have been identified, most of which are gaseous organic pollutants. In this study, TiO2@diatomite catalysts with various loading amounts of TiO2 were fabricated using a facile solvothermal method with anhydrous ethanol as a solvent for the removal of VOCs. X-ray diffraction analysis revealed that TiO2 has an anatase phase and the introduction of diatomite has no negative effect. The catalysts were characterized using scanning electron microscopy and transmittance electron microscopy techniques. The results indicate that after introducing diatomite, TiO2 nanoparticles are mostly square-like and intact, and are uniformly immobilized in the diatomite. Finally, their photocatalytic performance was investigated using liquid ultraviolet spectrometry and gas chromatography-mass spectrometry. Among the catalysts tested, 0.35TiO2@diatomite (with a mass ratio of TiO2 to diatomite of 0.35) exhibited higher photocatalytic activity than the other samples, i.e., pure TiO2 and diatomite, and could effectively remove acetone and benzene, demonstrating its potential market application and practical significance

Chemogenetic Minitool for Dissecting the Roles of Protein Phase Separation.

Biomolecular condensate is an emerging structural entity that regulates various cellular processes. Recent studies have discovered the phase-separation (PS) capability of several transcription factors (TFs) including YAP/TAZ upon biological stimuli, which provide new mechanisms of gene regulation. However, it remains mostly unanswered as to whether PS from a diffuse state to a phase-separated state promotes gene transcription. To address this question, we have designed a chemogenetic tool, dubbed SPARK-ON, which manipulates the PS of YAP and TAZ without a biological stimulus, forming condensates that are transcriptionally active, containing the DNA-binding partner TEAD, genomic DNA, transcriptional machinery, and nascent RNA. Most importantly, PS of TAZ increases the transcription of its target genes. Therefore, our data indicate that PS promotes gene transcription of TAZ. SPARK-ON is advantageous to current mutagenesis-based approaches that are often problematic when mutagenesis affects the transcriptional activity of a TF. Furthermore, protein abundance levels also affect gene transcription, but PS depends on protein abundance because PS occurs only when the protein level is above a saturation concentration. SPARK-ON decouples PS from protein abundance levels without introducing mutations and thus will find important applications in understanding the biological roles of PS for many TFs and other biomolecular condensates