Graphene oxide, as an emerging material for contaminants removal,possesses relatively large specific surface area, and it shows good dispersion in water phase due to the hydrophilicessence resulted from abundant oxygen-containing functional groups on the edge, thus leading to a potential excellent adsorbent. Current studies revealthat, because graphene oxide is negatively-charged in a wide range of pHs, the removal efficiency of heavy metals and cationic dyes by graphene oxide is significantly higher than by traditional adsorbents, like activated carbon. However, its applications are still limited due to its structural defects. For example, its π domain is destructed during fabrication process. Therefore, certain structural modifications need to be conducted on the purpose of improving its performance, achieving a better result in water purification. This paper presented the preparation and structure of graphene oxide, and reviewed the adsorption behaviors, adsorption mechanisms, adsorption models and influence factors of heavy metals and organic pollutants on graphene oxide and its composites, respectively. In view of unresolved issues, further research should focus on comprehensive adsorption mechanisms, more facile and effectivemethods for structural modifications and the treatment of graphene oxide after adsorption process. 相似文献
Redox processes during bank filtration were evaluated in Berlin, where bank filtered water is abstracted for drinking water
production. The investigations included the mapping of the infiltration zone, a column study and hydrochemical analyses of
the groundwater sampled between lake and production well. The organic carbon content increased and the permeability of the
lake sediments decreased with distance from the shoreline. The most important changes with regard to the redox state of the
infiltrate occurred within the first metre of flow. Infiltration was mostly anoxic, as oxygen was rapidly consumed within
the organic rich sediments. The infiltration zone revealed a vertical redox stratification with hydrochemical conditions becoming
more reducing with depth rather than with distance from the lake. The redox zones were found to be very narrow below the lake
and wider towards the production wells, suggesting that other than differing flow paths, reaeration after infiltration may
also occur and possible mechanisms are presented. Redox conditions were influenced by strong annual temperature variations
of the surface water affecting the microbial activity. Aerobic infiltration only took place close to the shore in winter. 相似文献
Twenty-five stations were selected along the UAE coastal region to delineate the distribution and to determine the source
of total petroleum hydrocarbon (TPH), total organic carbon (TOC), total Kjeldhal nitrogen (TKN), polycyclic aromatic hydrocarbons
(PAHs) and polychlorinated biphenyls (PCBs). The concentrations of TPH ranged between 46 and 223 mg/kg and the level of TOC
was in the range from 0.044 to 17.8 wt%, while TPAHs occupied the range of 5–102.2 μg/kg. On the other hand, TPCBs showed
values between 60 and 205 μg/kg and TKN ranged from 104 to 1,073 mg/kg. The present study shows that the distribution of organic
compounds in UAE sediments were within safe limits comparing with previous studies. The present study revealed that TOC can
be used as an indicator of oil pollution in heavily oiled sediments. The highest values of TOC, TPH, TPAHs and TPCBs related
to the stations covered in fine sand due to adsorption properties and the large surface areas of the grains. The evaporation
of low-boiling point compounds from surface layers leads to the enrichment of sediments with a thick residual. Al Sharjah-1
exhibited the highest values of TPH and TOC at Ras Al-Khaima-5, Umm Al-Quwen-1 and Dubai-1, while the highest values of TPAHs
were at KhorFakkan-9, the highest value of TPCBs was at Ajman-2, and the highest values of TKN were at KhorFakkan-1, KhorFakkan-6
and Dubai-1. 相似文献
In 2015, China committed to reducing its emission intensity per unit of gross domestic product by 60–65% from its 2005 rate and to peak its carbon emission by 2030. Problems related to local pollutants and haze are simultaneously worsening in China. This article focuses on the critical topic of co-controlling carbon emission and local air pollutants and evaluates the co-benefit of carbon mitigation in local pollutant reduction by using a partial equilibrium model that links carbon emission and local air pollutants at the technological level. Three conclusions can be drawn from the scenario analysis. First, in the reference scenario, energy consumption and carbon emission continue to increase and air quality is expected to deteriorate in the future. Therefore, current pollutant control measures should be improved. Second, local pollutants will be significantly reduced in the end-of-pipe control scenario, but the reduction will still be inadequate to fulfil the air quality target. Third, emissions of SO2, NOx, and PM2.5 in 2030 will be reduced by 78.85%, 77.56%, and 83.32%, respectively, compared with the 2010 levels in the co-control scenario involving the peaking effort in China. Therefore, the air quality targets can also be achieved when the peaking target is fulfilled. The Nationally Determined Contribution (INDC) of China to peak its emission by 2030 is consistent with its domestic interest to improve local air quality.
POLICY RELEVANCE
China submitted its INDC to the United Nations Framework Convention on Climate Change in 2015 and has promised to peak its carbon emission by 2030. In recent years, China has also faced severe pressure to address its air pollution problem. Air quality is an important driving force to incentivize more ambitious mitigation measures that can contribute to the simultaneous reduction of carbon emission and air pollutants. Air quality benefit provides a strong justification for the INDC of China and the possibility of early peaking. Moreover, the co-benefit in China can be a reference for other developing countries that are facing the same challenge and can reinforce the initiative of these countries to promote ambitious mitigation actions. 相似文献
Organic-rich black shale of the Upper Yangtze Basin from the Late Ordovician and Early Silurian is considered an excellent source rock in South China. The formation and preservation conditions of this resource are revealed by its geochemical characteristics in this study. Geochemical indices, including redox indices (V/(V + Ni), V/Cr, V/Sc, and Ni/Co) and primary productivity indices (P/Ti and Ba/Al), and paleoclimate, clastic flux and sedimentary rate analyses are presented to investigate the accumulation mechanism of organic matter. Redox indices suggest that a stagnant, anoxic environment predominated in the Upper Yangtze Basin during accumulation of Wufeng and Longmaxi formations. In contrast, ventilated and oxygenated marine conditions pervaded the Upper Yangtze Basin during deposition of Linxiang and Guanyinqiao formations. The concentrations of V and U demonstrate that accumulation of organic matter was mainly controlled by redox conditions. Besides, such factors as clastic fluxes, fresh water inflows or a mixed deposition with a rapid sedimentary rate cannot be ignored due to their influences on organic matter enrichment and preservation. However, weak co-variance relationship of TOC content and productivity proxies, including P/Ti and Ba/Al, demonstrates that the accumulation of organic matter was not controlled by primary productivity. Results of the present study suggest a depositional model that stresses the importance of tectonic movements and glacial events on the accumulation and preservation of organic matter. The model shows that the Upper Yangtze Basin was a semi-restricted basin system influenced by the isolation of Xuefeng, but also it implies that oxygen-depleted bottom water of the basin favored the accumulation and preservation of sedimentary organic matter, resulting in the formation of organic-rich black shale. 相似文献