Characteristics of volatile organic compounds and secondary organic aerosol pollution in different functional areas of petrochemical industrial cities in Northwest China

Microscopic Characterization of Individual Aerosol Particles in a Typical Industrial City and Its Surrounding Rural Areas in China

Transmission electron microscopy was used to analyze individual aerosol particles collected in Lanzhou (urban site) and its surrounding areas (rural site) in early 2023. The results revealed that from the pre-Spring Festival period to the Spring Festival period, the main pollutants at the urban site decreased significantly, while the PM2.5 and SO2 concentrations increased at the rural site. During the entire sampling period, the main particles at the urban site were organic matter (OM), secondary inorganic aerosols (SIA), and OM-SIA particles, while those at the rural site were OM, SIA, and soot particles. The degree of external mixing of single particles in both sites increased from the pre-Spring Festival period to the Spring Festival period. The proportion of the OM particles increased by 11% at the urban site, and the proportion of SIA particles increased by 24% at the rural site. During the Spring Festival, the aging of the soot particles was enhanced at the urban site and weakened at the rural site. At the urban site, the SIA particle size was more strongly correlated with the thickness of the OM coating during the pre-Spring Festival period, while the correlation was stronger at the rural site during the Spring Festival.

Recent advances of copolymer for water treatment

Increasing water pollution due to anthropogenic activities prompts the quest for an effective water treatment method. Polymeric materials have gained attention as adsorbents for water purification. Membranes are majorly made from homopolymeric materials. However, recent studies have focused on using copolymeric materials for improved performance. In this review, the basics of copolymerization including various types of copolymers, synthetic approaches, and their applications in various water pollutants removal are discussed in detail. Advances in water treatment technology using copolymeric materials as adsorbent/membranes in the last 4 years are covered with insights into the future outlook and areas of improvement in terms of copolymer composites for water treatment. Studies from the literature did not only reveal effectiveness of copolymer as a flocculant/antifouling materials and in removal of selective toxic metals, oil, and microbes but also demonstrated recyclability of the copolymer sorbents/membrane. Full exploration of unique copolymer textural and structural properties could lead to great advancement in water treatment process. PRACTITIONER POINTS: The copolymer types and synthetic methods are discussed. Application of copolymer as adsorbent/membranes for water treatment is presented. Recent advances show good pollutants removal for toxic metals, oil, and organics. Copolymer composites have great potential as adsorbent/membranes for future use in water treatment processes.

Investigation on ozone formation mechanism and control strategy of VOCs in petrochemical region: Insights from chemical reactivity and photochemical loss

To investigate disparities in VOCs pollution characteristics, O3 generation activity, and source apportionment outcomes resulting from photooxidation, online monitoring of 106 VOCs was conducted in Jinshan District, Shanghai from April to October 2020. The observed VOCs concentrations (VOCs-obs) were 47.1 ppbv and 59.2 ppbv for clear days (CD) and O3-polluted days (OPD), respectively. The increase in daytime concentrations of alkenes is a significant factor contributing to the enhanced atmospheric photochemical activity during the OPD period, corroborated by VOCs-loss, ozone formation potential (OFP), propy-equiv concentration, and LOH. The sensitivity analysis of O3-NOx-VOCs indicated that O3 formation was in a transitional regime towards NOx-limited conditions. The results of positive matrix factorization (PMF) demonstrated that refining and petrochemicals (20.8-25.0 %), along with oil and gas evaporation (15.6-16.7 %) were the main sources of VOCs concentrations. Notably, source apportionment based on VOCs-obs underestimated the contributions from sources of reactive components. It is worth highlighting that the sunlight impact & background source was identified as the major contributor to LOH (21.6 %) and OFP (25.3 %), signifying its significant role in O3 formation. This study reiterates the importance of controlling reactive VOC components to mitigate O3 pollution and provides a scientific foundation for air quality management, with emphasis on priority species and controlling sources.