Impacts of chlorine emissions on secondary pollutants in China

2020 ◽  
pp. 118177
Author(s):  
Yizhou Zhang ◽  
Junfeng Liu ◽  
Wei Tao ◽  
Songlin Xiang ◽  
Huazhen Liu ◽  
...  
Keyword(s):  
Secondary Pollutants

Electrospun-based TiO2 nanofibers for organic pollutant photodegradation: a comprehensive review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Khee Chung Hui ◽  
Hazwani Suhaimi ◽  
Nonni Soraya Sambudi
Keyword(s):  
Visible Light ◽  
Organic Pollutants ◽  
Organic Pollutant ◽  
Hollow Fibers ◽  
Promising Alternative ◽  
Tio2 Nanofibers ◽  
As Doping ◽  
Secondary Pollutants ◽  
Photocatalytic Reactors ◽  
Light Area

Abstract Titanium dioxide (TiO2) is commonly used as a photocatalyst in the removal of organic pollutants. However, weaknesses of TiO2 such as fast charge recombination and low visible light usage limit its industrial application. Furthermore, photocatalysts that are lost during the treatment of pollutants create the problem of secondary pollutants. Electrospun-based TiO2 fiber is a promising alternative to immobilize TiO2 and to improve its performance in photodegradation. Some strategies have been employed in fabricating the photocatalytic fibers by producing hollow fibers, porous fibers, composite TiO2 with magnetic materials, graphene oxide, as well as doping TiO2 with metal. The modification of TiO2 can improve the absorption of TiO2 to the visible light area, act as an electron acceptor, provide large surface area, and promote the phase transformation of TiO2. The improvement of TiO2 properties can enhance carrier transfer rate which reduces the recombination and promotes the generation of radicals that potentially degrade organic pollutants. The recyclability of fibers, calcination effect, photocatalytic reactors used, operation parameters involved in photodegradation as well as the commercialization potential of TiO2 fibers are also discussed in this review.

scholarly journals PM2.5 and Ozone Air Pollution Levels Have Not Dropped Consistently Across the US Following Societal Covid Response

2020 ◽  
Author(s):  
Bujin Bekbulat ◽  
Joshua S. Apte ◽  
Dylan B Millet ◽  
Allen Robinson ◽  
Kelley C. Wells ◽  
...  
Keyword(s):  
Air Pollution ◽  
Environmental Protection Agency ◽  
Fine Particulate Matter ◽  
Pollution Levels ◽  
Secondary Pollutants ◽  
The Us ◽  
Many Sources ◽  
Primary Pollutant ◽  
Ozone Levels ◽  
At Home

<p>Analysis of a large national dataset of fine particulate matter (PM2.5) and ozone air pollution from the US Environmental Protection Agency indicate opposing differences in average concentrations during the covid response period, relative to expected levels. These are the two most important pollutants in terms of public health impacts and regulatory non-attainment in the US. Post-covid response, average PM2.5 levels are slightly higher (~5%) than expected; average ozone levels are slightly lower (~5%). The size of post-response ozone anomaly has decreased with time and by week 6 after the first stay-at-home order was enacted (April 29- May 5, 2020), ozone levels were higher than expected. In addition, no individual US state had lower-than-expected PM2.5 and ozone for all weeks post- covid response. Two non-covid factors, meteorology and regional transport, do not fully explain observed trends. These findings are unexpected given the large reduction in many household’s activities associated with “stay at home” and other covid responses. We hypothesize that this result partly arises from the fact that ozone and the majority of PM2.5 are secondary pollutants formed in the atmosphere from emissions from many sources (i.e., not just traffic). Preliminary analysis of nitrogen dioxide (NO2) data in a few cities reveals substantially lower-than-expected (~30%) concentrations post-covid. NO2 is a primary pollutant and is much more strongly associated with traffic than PM2.5 or ozone. </p><p><br></p>

scholarly journals Atmospheric oxidation capacity in Chinese megacities during photochemical polluted season: radical budget and secondary pollutants formation

2018 ◽  
Author(s):  
Zhaofeng Tan ◽  
Keding Lu ◽  
Meiqing Jiang ◽  
Rong Su ◽  
Hongli Wang ◽  
...  
Keyword(s):  
Fine Particle ◽  
Fine Particles ◽  
Nox Reduction ◽  
Ozone Production ◽  
Atmospheric Oxidation ◽  
Ozone Pollution ◽  
Oxidation Capacity ◽  
Radical Chemistry ◽  
Budget Analysis ◽  
Secondary Pollutants

Abstract. Atmospheric oxidation capacity is the core of converting fresh-emitted substances to secondary pollutants. In this study, we present the in-situ measurements at four Chinese megacities (Beijing, Shanghai, Guangzhou, and Chongqing) in China during photochemical polluted seasons. The atmospheric oxidation capacity is evaluated using an observational-based model with the input of radical chemistry precursor measurements. The radical budget analysis illustrates the importance of HONO and HCHO photolysis, which contribute nearly half of the total radical primary sources. The radical propagation is efficient due to abundant of NO in the urban environments. Hence, the production rate of secondary pollutants, i.e. ozone and fine particle precursors (H2SO4, HNO3, and ELVOCs) is fast resulting in secondary air pollution. The ozone budget demonstrates that strong ozone production occurs in the urban area which results in fast ozone concentration increase locally and further transported to downwind areas. On the other hand, the O3-NOx-VOC sensitivity tests show that ozone production is VOC-limited, among which alkenes and aromatics should be first mitigated for ozone pollution control in the presented four megacities. However, NOx emission control will lead to more server ozone pollution due to the drawback-effect of NOx reduction. For fine particle pollution, the role of HNO3−NO3− partitioning system is investigated with a thermal dynamic model (ISORROPIA2) due to the importance of particulate nitrate during photochemical polluted seasons. The strong nitrate acid production converts efficiently to nitrate particles due to high RH and ammonium-rich conditions during photochemical polluted seasons. This study highlights the efficient radical chemistry maintains the atmospheric oxidation capacity in Chinese megacities, which results in secondary pollutions characterized by ozone and fine particles.

Sources of Air Pollution

2018 ◽  
pp. 220-258
Author(s):  
Abderrezak Khelfi
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Adverse Effects ◽  
Chemical Reactions ◽  
Dust Storms ◽  
Pollution Sources ◽  
Atmospheric Gases ◽  
Secondary Pollutants ◽  
Harmful Substances ◽  
Life On Earth

This chapter describes how air is a complex natural gaseous system essential to support life on Earth. Air pollution comes from a wide variety of sources, which discharge of harmful substances into the atmosphere, causing adverse effects to humans and the environment. They can be natural or anthropogenic. Natural air pollution sources are multiple and include volcanic eruption, fire, ocean vapors, dust storms and fermentation of organic materials. However, the range and quantities of chemicals discharged into the atmosphere from industry, transport, agriculture, energy production, domestic heating, and many other human activities, have increased dramatically. Some pollutants are emitted directly into the atmosphere and are known as primary pollutants (NOx, SOx, particulate matter, etc.). Others are formed in the air as a result of chemical reactions with other pollutants and atmospheric gases; these are known as secondary pollutants like ozone. This chapter provides an overview on air pollution sources as well as the ways in which pollutants can affect human health and the environment.

scholarly journals Petrochemical and Industrial Sources of Volatile Organic Compounds Analyzed via Regional Wind-Driven Network in Shanghai

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 760 ◽  
Author(s):  
Wanyi Qiu ◽  
Shule Li ◽  
Yuhan Liu ◽  
Keding Lu
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Surface Ozone ◽  
Industrial Area ◽  
Ozone Pollution ◽  
Regional Network ◽  
Local Circulation ◽  
Near Surface ◽  
Secondary Pollutants ◽  
Volatile Organic

Due to the development of industrialization and urbanization, secondary pollution is becoming increasingly serious in the Yangtze River Delta. Volatile organic compounds (VOCs) are key precursors of the near-surface ozone, secondary organic aerosol (SOA), and other secondary pollutants. In this study, we chose a serious ozone pollution period (01 May–31 July 2017) in Jinshan, which is a petrochemical and industrial area in Shanghai. We explored the VOCs distribution characteristics and contribution to secondary pollutants via constructing a regional network based on wind patterns. We determined that dense pollutants were accumulated at adjacent sites under local circulation (LC), and pollution from petrochemical discharge was more serious than industry for all sites under southeast (SE) wind. We also found that cyclopentane, o-xylene, m/p-xylene, 1-3-butadiene, and 1-hexene were priority-controlled species as they were most vital to form secondary pollutants. This study proves that regional network analysis can be successfully applied to explore pollution characteristics and regional secondary pollutants formation.

Assessment and Characterization of Hybrid Mesoporous Material MCM With Titanium Dioxide for Water Treatment

2019 ◽  
Author(s):  
Jiajun Xu
Keyword(s):  
Trace Metals ◽  
Mesoporous Material ◽  
Positive Impact ◽  
Inductively Couple Plasma ◽  
Polluted Water ◽  
Maximum Adsorption Capacity ◽  
Icp Ms ◽  
Secondary Pollutants ◽  
Pass Through

Abstract In the current study, a new method was developed to synthesize the hybrid mesoporous material with metallic oxides, MCM-48 with TiO2, at an improved efficiency and reduced cost. The results have shown an over 95% adsorption efficiency for trace metals for the hybrid MCM-48 with TiO2 materials, and a significantly improved maximum adsorption capacity compared to pure MCM-48. Its unique hybrid structured allows the polluted water to pass through the strong yet highly permeable structure of mesoporous material, while gives enough time for the pollutants to react with the TiO2 infused on the porous structure so that the polluted water can be treated without introducing secondary pollutants. The microstructures of the MCM-48 with and without TiO2 are characterized using SEM with EDS and Porosimiter. The effectiveness of wastewater treatment is measured using Inductively Couple Plasma-Mass Spectrometer (ICP-MS). The significant improvements observed here is likely due to the infused TiO2 to the base MCM-48 structure, which also agree with the authors’ previous finding. It is noticed that, while the higher concentration of TiO2 has a positive impact on the adsorption of trace metals, the higher concentration of Ti source does not necessarily yield significantly higher concentration of TiO2 in the final product. Future study is needed to further explore this hybrid mesoporous material for other pollutants treatment, and to obtain a further understanding of its mechanisms.

scholarly journals Microcystis aeruginosa Synergistically Facilitate the Photocatalytic Degradation of Tetracycline Hydrochloride and Cr(VI) on PAN/TiO2/Ag Nanofiber Mats

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 628 ◽  
Author(s):  
Lei Wang ◽  
Changbo Zhang ◽  
Rong Cheng ◽  
Jafar Ali ◽  
Zhenbo Wang ◽  
...  
Keyword(s):  
Microcystis Aeruginosa ◽  
High Efficiency ◽  
Reaction Rate Constant ◽  
Active Species ◽  
Harmful Algae ◽  
Cyanobacterial Blooms ◽  
Tetracycline Hydrochloride ◽  
Algae Blooms ◽  
Secondary Pollutants ◽  
Nanofiber Mats

Cyanobacterial blooms can cause serious damage to aquatic ecosystems. However, we have demonstrated that typical algae-blooming species Microcystis aeruginosa (M. aeruginosa) combined with photocatalysts could synergistically facilitate the photodecontamination of tetracycline hydrochloride (TC) and Cr(VI). In this study, for the first time, harmful algae were successfully converted into photoreactive bionano hybrid materials by immobilizing M. aeruginosa cells onto polyacrylonitrile (PAN)-TiO2/Ag hybrid nanofibers, and their photocatalytic activity was evaluated. The addition of M. aeruginosa significantly improved the photodecontamination, and the reaction rate constant (k) values of TC and Cr(VI) degradation by M. aeruginosa-PAN/TiO2/Ag nanofiber mats were 2.4 and 1.5-fold higher than that of bare PAN/TiO2/Ag nanofiber. Photoreaction caused damage to algae cells, but no microcystin was found that had been photodegraded simultaneously. The effects of various active species were also investigated, and the photodegradation mechanism was proposed. Recycling tests revealed that this flexible M. aeruginosa-PAN/TiO2/Ag hybrid mat had potential application in the removal of mixed organic and inorganic pollutants with high efficiency and without secondary pollutants. Thus, harmful algae blooms could serve as an efficient materials to remove toxic pollutants in a sustainable way under visible light irradiation.

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