Biodegradation of waste refrigerator polyurethane by mealworms

● Waste refrigerator polyurethane (WRPU) was ingested and biodegraded by mealworms. ● The carbon in WRPU-based frass was lower than that in WRPU. ● Urethane groups in WRPU were broken down after ingestion by mealworms. ● Thermal stability of WRPU-based frass were deteriorated compared to that of WRPU. ● Gut microbiomes of mealworms fed using WRPU were distinct from that fed using bran. Refrigerator insulation replacement results in discarding a large amount of waste refrigerator polyurethane (WRPU). Insect larvae like mealworms have been used to biodegrade pristine plastics. However, knowledge about mealworms degrading WRPU is scarce. This study presents an in-depth investigation of the degradation of WRPU by mealworms using the micro-morphology, composition, and functional groups of WRPU and the egested frass characteristics. It was found that the WRPU debris in frass was scoured, implying that WRPU was ingested and degraded by mealworms. The carbon content of WRPU-based frass was lower than that of WRPU, indicating that mealworms utilized WRPU as a carbon source. The urethane groups in WRPU were broken, and benzene rings’ C=C and C–H bonds in the isocyanate disappeared after being ingested by mealworms. Thermal gravimetric-differential thermal gravimetry analysis showed that the weight loss temperature of WRPU-based frass was 300 °C lower than that of WRPU, indicating that the thermal stability of WRPU deteriorated after being ingested. The carbon balance analysis confirmed that carbon in the ingested WRPU released as CO₂ increased from 18.84 % to 29.80 %, suggesting that WRPU was partially mineralized. The carbon in the mealworm biomass ingesting WRPU decreased. The possible reason is that WRPU does not supply sufficient nutrients for mealworm growth, and the impurities and odor present in WRPU affect the appetite of the mealworms. The microbial community analysis indicated that WRPU exerts a considerable effect on the gut microorganism of mealworms. These findings confirm that mealworms degrade WRPU.     

Formation of halonitromethanes from methylamine in the presence of bromide during UV/Cl2 disinfection

The UV/Cl₂ process is commonly used to achieve a multiple-barrier disinfection and maintain residuals. The study chose methylamine as a precursor to study the formation of high-toxic halonitromethanes (HNMs) in the presence of bromide ions (Br⁻) during UV/Cl₂ disinfection. The maximum yield of HNMs increased first and then decreased with increasing concentration of Br⁻. An excessively high concentration of Br⁻ induced the maximum yield of HNMs in advance. The maximum bromine incorporation factor (BIF) increased, while the maximum bromine utilization factor (BUF) decreased with the increase of Br⁻ concentration. The maximum yield of HNMs decreased as pH value increased from 6.0 to 8.0 due to the deprotonation process. The BUF value remained relatively higher under an acidic condition, while pH value had no evident influence on the BIF value. The maximum yield of HNMs and value of BUF maximized at a Cl₂:Br⁻ ratio of 12.5, whereas the BIF value remained relatively higher at low Cl₂:Br⁻ ratios (2.5 and 5). The amino group in methylamine was first halogenated, and then released into solution as inorganic nitrogen by the rupture of C-N bond or transformed to nitro group by oxidation and elimination pathways. The maximum yield of HNMs in real waters was higher than that in pure water due to the high content of dissolved organic carbon. Two real waters were sampled to verify the law of HNMs formation. This study helps to understand the HNMs formation (especially brominated species) when the UV/Cl₂ process is adopted as a disinfection technique.     

Antimony transformation and mobilization from stibnite by an antimonite oxidizing bacterium Bosea sp. AS-1

Soils and waters are heavily contaminated by antimony in Xikuangshan（XKS） mine area.It is widely accepted that oxidative dissolution of sulfide minerals and aqueous dissolution are the most prevalent geochemical mechanisms for the release of Sb to the environment.Bosea sp. AS-1 is an antimonite-oxidizer isolated from the mine slag in Xikuangshan Sb mine. Whole genome sequencing revealed the presence of multiple sulfur-oxidizing genes,antimony（Sb） metabolism genes and carbon fixation genes in AS-...     

Sources of ambient non-methane hydrocarbon compounds and their impacts on O3 formation during autumn, Beijing

The field observation of 54 non-methane hydrocarbon compounds (NMHCs) was conducted from September 1 to October 20 in 2020 during autumn in Haidian District, Beijing. The mean concentration of total NMHCs was 29.81 ± 11.39 ppbv during this period, and alkanes were the major components. There were typical festival effects of NMHCs with lower concentration during the National Day. Alkenes and aromatics were the dominant groups in ozone formation potential (OFP) and OH radical loss rate (L_OH). The positive matrix factorization (PMF) running results revealed that vehicular exhaust became the biggest source in urban areas, followed by liquefied petroleum gas (LPG) usage, solvent usage, and fuel evaporation. The box model coupled with master chemical mechanism (MCM) was applied to study the impacts of different NMHCs sources on ozone (O₃) formation in an O₃ episode. The simulation results indicated that reducing NMHCs concentration could effectively suppress O₃ formation. Moreover, reducing traffic-related emissions of NMHCs was an effective way to control O₃ pollution at an urban site in Beijing.     

A facial strategy to efficiently improve catalytic performance of CoFe2O4 to peroxymonosulfate

Cobalt iron spinel (CoFe₂O₄) has been considered as a good heterogeneous catalysis to peroxymonosulfate (PMS) in the degradation of persistent organic pollutants due to its magnetic properties and good chemical stability. However, its catalytic activity needs to be further improved. Here, a facial strategy, “in-situ substitution”, was adopted to modify CoFe₂O₄ to improve its catalytic performance just by suitably increasing the Co/Fe ratio in synthesis process. Compared with CoFe₂O₄, the newly synthesized Co_1.5Fe_1.5O₄, could not only significantly improve the degradation efficiency of phenol, from 50.69 to 93.6%, but also exhibited more effective mineralization ability and higher PMS utilization. The activation energy advantage for phenol degradation using Co_1.5Fe_1.5O₄ was only 44.2 kJ/mol, much lower than that with CoFe₂O₄ (127.3 kJ/mol). A series of related representations of CoFe₂O₄ and Co_1.5Fe_1.5O₄ were compared to explore the possible reasons for the outstanding catalytic activity of Co_1.5Fe_1.5O₄. Results showed that Co_1.5Fe_1.5O₄ as well represented spinel crystal as CoFe₂O₄ and the excess cobalt just partially replaced the position of iron without changing the original structure. Co_1.5Fe_1.5O₄ had smaller particle size (8.7 nm), larger specific surface area (126.3 m²/g), which was more favorable for exposure of active sites. Apart from the superior physical properties, more importantly, more reactive centers Co (Ⅱ) and surface hydroxyl compounds generated on Co_1.5Fe_1.5O₄, which might be the major reason. Furthermore, Co_1.5Fe_1.5O₄ behaved good paramagnetism, wide range of pH suitability and strong resistance to salt interference, making it a new prospect in environmental application.     

Regional differential decomposition and convergence of rural green development efficiency: evidence from China

Environmental Science and Pollution Research - An objective understanding of the current situation and influencing factors of rural green development in China is an important prerequisite for...     

Supervisor-Directed Emotional Labor as Upward Influence: An Emotions-as-Social-Information Perspective

To access organizational resources, subordinates often strive to influence supervisors' impressions. Moreover, subordinates' interactions with supervisors are known to be ripe with emotions. Nevertheless, research on upward impression management has rarely examined how subordinates' emotion regulation in supervisor interactions may shape their tangible outcomes. The present study introduces subordinates' emotional labor toward supervisors as a novel means of upward influence. Building on the emotions-as-social-information model, we propose that supervisor-directed emotional labor indirectly relates with supervisory reward recommendations by shaping supervisors' liking and perceived competence of subordinates. Moreover, we cast supervisors' epistemic motivation as a boundary condition for these indirect relations. We tested these notions using time-lagged data from 377 subordinates and 91 supervisors. When supervisors' epistemic motivation was higher (but not lower), (1) supervisor-directed surface acting related negatively with supervisors' liking and perceived competence of subordinates and (2) supervisor-directed deep acting related positively with supervisors' liking of subordinates. Liking and perceived competence, in turn, related positively with supervisors' willingness to recommend subordinates for organizational rewards. These findings highlight supervisor-directed emotional labor as an upward impression management strategy with both beneficial (deep acting) and detrimental (surface acting) implications, and they illustrate important mechanisms and a key contingency factor for these consequences.     

SCR脱硝技术在水泥窑烟气治理中的应用进展

基于水泥窑烟气氮氧化物治理的SCR脱硝技术和水泥生产配套问题,分析了水泥窑烟气特点和治理难点.综述了目前关于水泥窑烟气4种SCR脱硝技术工艺流程和布置,比较了不同SCR脱硝技术的适应性和优缺点,并对SCR脱硝技术在水泥窑的工程应用、中试及研究成果进行了介绍.对水泥窑SCR脱硝过程中出现的高粉尘、粒度小、催化剂中毒问题进行了详细分析,提出了解决方法,最后从满足水泥窑氮氧化物治理工业应用的角度,对水泥窑烟气治理SCR脱硝技术和催化剂进行了展望.     

Control of exhaled SARS-CoV-2-laden aerosols in the interpersonal breathing microenvironment in a ventilated room with limited space air stability

The Coronavirus Disease 2019 (COVID-19) highlights the importance of understanding and controlling the spread of the coronavirus between persons. We experimentally and numerically investigated an advanced engineering and environmental method on controlling the transmission of airborne SARS-CoV-2-laden aerosols in the breathing microenvironment between two persons during interactive breathing process by combining the limited space air stability and a ventilation method. Experiments were carried out in a full-scale ventilated room with different limited space air stability conditions, i.e., stable condition, neutral condition and unstable condition. Two real humans were involved to conducted normal breathing process in the room and the exhaled carbon dioxide was used as the surrogate of infectious airborne SARS-CoV-2-laden aerosols from respiratory activities. A correspondent numerical model was established to visualize the temperature field and contaminated field in the test room. Results show that the performance of a ventilation system on removing infectious airborne SARS-CoV-2-laden aerosols from the interpersonal breathing microenvironment is dependent on the limited space air stability conditions. Appropriate ventilation method should be implemented based on an evaluation of the air condition. It is recommended that total volume ventilation methods are suitable for unstable and neutral conditions and local ventilation methods are preferable for stable conditions. This study provides an insight into the transmission of airborne SARS-CoV-2-laden aerosols between persons in ventilated rooms with different limited space air stability conditions. Useful guidance has been provided to cope with COVID-19 in limited spaces.