Particulate matter (PM) is a complex mixture of solid particles and liquid droplets suspended in the air with varying size, shape, and chemical composition which intensifies significant concern due to severe health effects. Based on the well-established human health effects of outdoor PM, health-based standards for outdoor air have been promoted (e.g., the National Ambient Air Quality Standards formulated by the U.S.). Due to the exchange of indoor and outdoor air, the chemical composition of indoor particulate matter is related to the sources and components of outdoor PM. However, PM in the indoor environment has the potential to exceed outdoor PM levels. Indoor PM includes particles of outdoor origin that drift indoors and particles that originate from indoor activities, which include cooking, fireplaces, smoking, fuel combustion for heating, human activities, and burning incense. Indoor PM can be enriched with inorganic and organic contaminants, including toxic heavy metals and carcinogenic volatile organic compounds. As a potential health hazard, indoor exposure to PM has received increased attention in recent years because people spend most of their time indoors. In addition, as the quantity, quality, and scope of the research have expanded, it is necessary to conduct a systematic review of indoor PM. This review discusses the sources, pathways, characteristics, health effects, and exposure mitigation of indoor PM. Practical solutions and steps to reduce exposure to indoor PM are also discussed.
Pillar[n]arene-based supramolecular polymers have
attracted great interest because of their tunable morphologies and
external stimuli responsiveness. However, most of the investigations
of supramolecular polymers previously reported were focused on their
formation and transformation, and investigations on their applications
are rare. Herein, we designed and prepared hybrid polymeric materials
by incorporating Pd nanoparticles into a supramolecular polymer, constructed
from a pillar[5]arene dimer and a three-arm guest. The obtained hybrid
polymer was fully characterized by scanning electron microscopy, transmission
electron microscopy, X-ray photoelectron spectroscopy, scanning electron
microscopy–energy-dispersive X-ray mapping, and X-ray diffraction
technologies. Importantly, the hybrid supramolecular polymeric materials
exhibited desirable catalytic activity for reductions of toxic nitroaromatics
and C–C bond-forming Suzuki–Miyaura reaction in aqueous
solution.
Mechanically interlocked molecules are a class of smart supramolecular species because of their interesting topological structure and application in various areas, such as biology and nanoscience. In this work, we used "multicomponent reaction" to fabricate a new [2]rotaxane based on pillar[5]arene from different small-sized molecules. The molecular structure of the obtained [2]rotaxane R was confirmed by 1 H and 13 C NMR, high-resolution electrospray ionization mass spectrometry, twodimensional nuclear Overhauser effect spectroscopy, and density functional theory studies. Interestingly, the [2]rotaxane-based organometallic cross-linked catalyst (Pd@R) was easily constructed via the coordination between triazole groups and Pd(NO 3 ) 2 . Pd@R proved to be a good catalyst for the Suzuki−Miyaura coupling reaction with excellent stability and repeatability.
In this study, an integrated system comprised of zero-valent iron (ZVI) reduction and ZVI-based Fenton oxidation processes (ZVI-ZVI/H 2 O 2 ) was applied for the selective removal of nitroaromatic compounds (NACs) from 2,4-dinitroanisole (DNAN) producing wastewater. For the ZVI reduction process, at a hydraulic retention time (HRT) of 6 h and neutral pH of 7.2, removal efficiencies of 2,4-dinitroanisole (DNAN), 2,4-dinitrophenol (DNP) and 2,4-dinitrochlorobenzene (DNCB) were as high as 81.3 AE 3.6%, 80.6 AE 1.8% and 90.9 AE 3.5%, respectively, demonstrating the excellent performance of ZVI. For the ZVI/ H 2 O 2 oxidation process, the optimal pH and H 2 O 2 dosage were found to be 3.0 and 100 mmol L À1 , respectively. Under these optimal conditions, NACs and their degradation intermediates could be removed selectively and effectively in the coupled ZVI reduction and ZVI/H 2 O 2 oxidation process, as was indicated by the low UV 254 value of 0.104 AE 0.003 and the low TOC removal efficiency of 32.4 AE 0.7% in the effluent. Ferrous ions could be generated in situ through the corrosion of the metal iron in both the ZVI reduction process and the ZVI/H 2 O 2 oxidation process, giving rise to a potent Fenton-type reaction.In addition, the enhanced Fenton reaction with the aid of reaction between Fe 0 and Fe 3+ was probably due to the presence of Fe 0 in the ZVI/H 2 O 2 oxidation process, which promoted the utilization efficiency of the Fenton catalyst, i.e., Fe 2+ . Compared to the sequential ZVI reduction and homogeneous Fenton oxidation process (ZVI-Fe 2+ /H 2 O 2 ), the low consumption of iron shavings, the reduced H 2 O 2 consumption and the low yield of ferric sludge made the integrated ZVI-ZVI/H 2 O 2 process promising for the treatment of NAC containing wastewater.
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