Characterization of PM2.5 Mass Concentration in the Onshore of Sanya, China

Numbers of real-time data(E-BAM)of PM2.5 were collected in the period from Jan 8th 2012 to Jan 1st 2013 at the laboratory of Tropical Ocean University(Sanya,China).The average mass concentration was 19.7μg/m³.The highest 40.5μg/m³in October compared to the lowest 14.1μg/m³in July.From a seasonal perspective,the average PM2.5 mass concentration in fall and winter are relatively higher than that in both spring and summer.On the basis of satellite map of fire points and backward trajectories of the air masses,we primarily deduced that the PM2.5 in Sanya may be caused by the biomass burning and industrial pollutants from the area of Pearl River Delta of China and the Indo-China peninsula(e.g.Vietnam,Laos).

Recent progress of MgO-based materials in CO_(2) adsorption and conversion:Modification methods,reaction condition,and CO_(2) hydrogenation

Integrated CO_(2) capture and conversion of(ICCC)is one of the most effective solutions to reduce anthropogenic CO_(2) emissions,which has attracted extensive public attention.Dual functional materials(DFMs),including adsorbent and catalyst,are the key components to achieve ICCC.Magnesium oxide(MgO)is an ideal adsorbent for ICCC,since it is characterized by high theoretical adsorption capacity,low cost,low energy consumption and extensive sources.It can also be used as DFMs in combination with the Ni catalysts.MgO not only can act as an adsorbent in DFMs but also enhance the catalytic performance of Ni.This review summarizes the advantages and modification methods of MgO as adsorbent and the influence of its adsorption conditions on the adsorption performance.Moreover,the important role of MgO in facilitating the catalytic conversion of CO_(2) is highlighted.Future research focuses are proposed for the development of MgO based DFMs with high adsorption capacity,high stability,conversion,and selectivity as well as low cost and energy consumption.

Regulating the electronic structure of Ir single atoms by ZrO_(2)nanoparticles for enhanced catalytic oxidation of formaldehyde at room temperature

Developing low-loading single-atom catalysts with superior catalytic activity and selectivity in formaldehyde(HCHO)oxidation at room temperature remains challenging.Herein,ZrO_(2)nanoparticles coupled low-loading Ir single atoms in N-doped carbon(Ir_(1)-N-C/ZrO_(2))was prepared.The optimal Ir_(1)-N-C/ZrO_(2)with 0.25 wt%Ir loading delivers the high HCHO removal and conversion efficiency(>95%)at 20℃,which is higher than that over Ir_(1)-N-C with the same Ir loading.The specific rate can reach 1285.6 mmol gIr^(-1)h^(-1),surpassing the Ir based catalysts reported to date.Density functional theory calculation results and electron spin resonance spectra indicate that the introduction of Zr O_(2)nanoparticles modulate the electronic structure of the Ir single atoms,promoting O_(2)activation to·O_(2)^(–).Moreover,the Ir-C-Zr channel is favorable for the dissociation of·O_(2)^(–)to active oxygen atom(*O),and further accelerates the transformation of HCHO and intermediates(dioxymethylene and formates)to CO_(2)and H_(2)O.This work provides a facile strategy to design low-loading single-atom catalysts with high catalytic activity toward HCHO oxidation.

非农业源排放增强大气二甲胺浓度并调节城市颗粒物成核

气态二甲胺(DMA)是大气新粒子生成的关键前体物,然而对其来源与空气和气候效应仍存在巨大争议.本研究率先对中国大气DMA浓度开展了南北跨区域与城市内部的走航观测.发现亚热带森林植物的DMA排放浓度可能南方远高于北方,同时记录到由工业脉冲排放所导致的全球最高大气DMA浓度.在高度城市化的上海地区,DMA浓度自市中心向外围逐渐降低且与人口密度关联.源排放的直接测试进一步表明中国区域和城市内部的大气二甲胺都深受非农业源排放的影响.大气化学传输模式也证实,居民DMA排放主导了上海城市大气颗粒物数浓度的贡献.该研究将外场观测、源排放测试与模型模拟相结合,呈现了中国大气二甲胺的全生命周期,为颗粒物污染防治和气候变化评估提供了有用参考.