A Novel Bi2O3 Modified C-Doped Hollow TiO2 Sphere Based On Glucose-Derived Carbon Sphere With Enhanced Visible Light Photocatalytic Activity

The hydrothermal method was used to synthesize carbon sphere, and the hard template synthesis method was used to prepared C-doped hollow TiO2 sphere (CT). Bismuth nitrate was used as bismuth source to modify CT. The composite material was oxidized in air atmosphere at 450℃ to obtain Bi2O3 modified C-doped TiO2(BCT) hollow spheres. The morphology, elemental composition and photocatalytic degradation efficiency of tetracyclines (TC) by BCT hollow spheres were characterized by various measurements. Additionally, the possible transformation pathways and degradation mechanism of tetracycline were revealed via LC-MS and trapping experiments. The experimental results show that the Bi nanoparticles are uniformly dispersed in the BCT hollow spheres. The photocatalyst exhibits enhanced degradation rate of TC (98.4% under visible-light within 180 min and 99.4% under natural light within 50 min) for its structure and narrow bandgap (2.87 eV). After five degradation cycles, the photocatalyst still remains high removal rate of 96.4% for TC. The results indicate that the photocatalyst may be promising for degrading antibiotic residuals remains. According to the trapping experiment, ·OH and h+ have a certain role on the photodegradation process, while ·O2− is the main active species for degrading TC.

Isolation and optimization of a glyphosate-degrading Rhodococcus soli G41 for bioremediation

A widely used herbicide for controlling weeds, glyphosate, is causing environmental pollution. It is necessary to remove it from environment using a cost-effective and eco-friendly method. The aims of this study were to isolate glyphosate-degrading bacteria and to optimize their degradative conditions required for bioremediation. Sixteen bacterial strains were isolated through enrichment and one strain, Rhodococcus soli G41, demonstrated a high removal rate of glyphosate than other strains. Response surface methodology was employed G41 strain to optimize distinct environmental factors on glyphosate degradation of G41 strain. The optimal conditions for the maximum glyphosate degradation were found to have the NH4Cl concentration of 0.663% and glyphosate concentration of 0.115%. Degradation analysis showed 47.1% of glyphosate in soil was degraded by G41 strain after 14 days. The presence of soxB gene in G41 strain indicates that the glyphosate is degraded via the eco-friendly sarcosine pathway. The results indicated that G41 strain has the potential to serve as an in-situ candidate for bioremediation of glyphosate polluted environments.

A Review of the some aspects for the development of ZnO based photocatalysts for a variety of applications

Today, one of the most important problems for humanity is the pollution of the environment with various organic compounds that worsen the health of the peoples. The most dangerous pollutants are complex compounds that do not degrade under natural conditions. One way to solve the problem of pollution is to use photocatalysis to degrade harmful compounds. Zinc oxide nanostructures exhibit attractive photocatalytic and antibacterial properties due to the increased reactivity of the nanoparticle surface, which allows the efficient decomposition of organic pollutants. In this review, various methods for enhancing the photoefficiency of ZnO nanostructures are considered. It is shown that ZnO nanoparticles with specific surfaces (spherical, nanowires, nanoflowers), which are characterized by a high surface area, have a high removal rate of various pollutants. Such methods of improving the photocatalytic properties of ZnO as the band gap engineering, doping with metal/nonmetal, the combination of ZnO with other materials, formation of hybrid structures are considered.

Photocatalysis and Biodegradation Coupled Intimately for Treatment of the Black-Odor Water

Black-odor water remains an important problem of water pollution control in China. An increasing number of studies have thus investigated combined technologies for water pollution. Among them, many researchers prefer the intimate coupling of photocatalysis and biodegradation (ICPB) for its characteristics of high efficiency and high removal rate for refractory organics. In this study, porous cellulose-TiO2, which has advantages of good responsiveness, stability, and friendliness towards microorganisms, was introduced into the ICPB system as a crucial carrier for cleaning black-odor water. The key factors of this system were changed to obtain the optimum conditions (carrier mass 4 g, pH 7, and light intensity 25 W), and three comparison protocols including UV-responsive photocatalysis (UPC), biodegradation (B), and the coupled (PB) were carried out. The results showed removal rates of 59.06% (UPC), 68.20% (B), and 92.06% (PB) for COD, 59.96% (UPC), 82.36% (B), and 97.16% (PB) for NH3–N, and 69.00% (UPC), 85.61% (B), and 94.83% (PB) for TP. Obviously, the coupled treatment exhibited the maximum removal rates for the three indexes. Moreover, with the coupled treatment, the effluent water quality could meet the requirement of Class III water of the Environmental Quality Standard for Surface Water (GB3838-2002).

Effects of microhabitat on rodent-mediated seed removal of endangered Kmeria septentrionalis in the karst habitat

Seed removal behaviors of rodents are largely influenced by microhabitat. Although the karst ecosystem is composed of a broad variety of microhabitats, we have no information on how they affect such behaviors. We investigated rodents’ seed removal behaviors in four karst microhabitats (stone cavern, stone groove, stone surface, and soil surface) using three types of Kmeria septentrionalis seeds: fresh, black (intact seeds with black aril that dehydrates and darkens), and exposed (clean seeds without the aril). We show that Rattus norvegicus, Leopoldamys edwardsi and Rattus flavipectus were the predominant seed predators. Even though all seed types experienced a high removal rate in all four microhabitats, but rodents preferentially removed seeds from the three stone microhabitats (stone caves: 69.71 ± 2.74%; stone surface: 60.53 ± 2.90%; stone groove: 56.94 ± 2.91%) compared to the soil surface (53.90 ± 2.92%). Seeds that had been altered by being exposed to the environment were more attractive to rodents than fresh seeds (76.25 ± 2.20% versus 36.18 ± 2.29%). The seed removal behavior of rodents was significantly affected by the microhabitat and seed type. Finally, seeds that had fallen on the soil surface microhabitat incurred a lower predation risk than seeds fallen on other microhabitats, which increased their probability to germinate. Our results indicate that the lower predation rate of seeds from the endangered K. septentrionalis dropped on the soil surface increases trees’ likelihood of survival.

PLANTER BOX RAINGARDEN FOR ZINC REMOVAL FROM STORM WATER

Urbanization creates problems for the natural water systems, such as an increase in run-off volume due to the impervious surfaces and a negative impact on groundwater recharge. These changes and exposure to contaminants such as suspended/dissolved solids and heavy metals severely degrade stormwater quality. In Christchurch, heavy metals such as zinc found in run-off, which is mainly sourced from galvanized roofing. The main idea of this research is to solve run-off issues at the source, along with the construction phase. This idea is aligned with the NZ's Unitary Plan to keep rainwater run-off after a new development equal or less than the run-off that occurred before the development. Different methods of treatment for roof run-off were evaluated in this research to propose a sustainable solution followed by an assessment. A multi-layered planter box raingarden was selected since it helps to landscape, improve water quality, and perform as an attenuation device. The research concentrated on maximizing water quality while maintaining a required flowrate. The planter box raingarden performed at a low vertical hydraulic conductivity rate of 164 mm/hr and achieved a high removal rate for heavy metals. The removal rate for dissolved zinc and total zinc was 99.7% and 99.1%, respectively. The results explained that the planter box raingarden performs well as an attenuation device while adsorb and filter contaminants remarkably.

Effects of surfactants on the remediation of petroleum contaminated soil and surface hydrophobicity of petroleum hydrocarbon degrading flora

It has been proven that surfactants used in the remediation of petroleum hydrocarbon contaminated soil have great application potential. In this study, the effects of five surfactants (SDBS, Tween80, Tween60, rhamnolipid and TRS-1) on leaching of petroleum hydrocarbons from soil were investigated through orthogonal experiments, and petroleum hydrocarbon components were analyzed by GC/MS. The effects of surfactants on the degradation of petroleum hydrocarbon were analyzed by the changes of microbial growth curve and surface hydrophobicity. The results showed that surfactant type, temperature and surfactant concentration had significant effects on the removal rate of petroleum hydrocarbon. Tween80, rhamnolipid and TRS-1 have good bio-friendliness and a high removal rate of petroleum hydrocarbons (up to 65%), suitable for the restoration of the soil used in the experiment And Surfactants exhibited a higher removal rate for small molecules and petroleum hydrocarbons with odd carbon atoms. Surfactants have a certain modification effect on the surface of relatively hydrophilic bacteria under the initial conditions, making their surface properties develop in the direction of enhanced hydrophobicity, and the hydrophobicity has increased from less than 20% to about 40%.