Facet effect of hematite on the hydrolysis of phthalate esters under ambient humidity conditions.

Phthalate esters (PAEs) have been extensively used as additives in plastics and wallcovering, causing severe environmental contamination and increasing public health concerns. Here, we find that hematite nanoparticles with specific facet-control can efficiently catalyze PAEs hydrolysis under ambient humidity conditions, with the hydrolysis rates 2 orders of magnitude higher than that in water saturated condition. The catalytic performance of hematite shows a significant facet-dependence with the reactivity in the order {012} > {104} ≫ {001}, related to the atomic array of surface undercoordinated Fe. The {012} and {104} facets with the proper neighboring Fe-Fe distance of 0.34-0.39 nm can bidentately coordinate with PAEs, and thus induce much stronger Lewis-acid catalysis. Our study may inspire the development of nanomaterials with appropriate surface atomic arrays, improves our understanding for the natural transformation of PAEs under low humidity environment, and provides a promising approach to remediate/purify the ambient air contaminated by PAEs.

Biodegradable Microplastics: A Review on the Interaction with Pollutants and Influence to Organisms.

Biodegradable plastics attract public attention as promising substitutes for traditional nondegradable plastics which have caused the serious white pollution problem due to their persistence. However, even for biodegradable plastics, natual conditions for the rapid and complete degradation are rare. Even more serious is that biodegradable plastics might be disintegrated into microplastics more rapidly than tranditional plastics, emerging as another threat to the environment. Similar to traditional microplastics, biodegradable microplastics could adsorb many pollutants by various physicochemical effects and release additives. Biodegradable microplastics have been confirmed to be toxic to the organisms as particle matter and the vector as pollutants. Under some conditions, biodegradable microplastics may pose more severe negative impacts on the organisms. With the fierely increasing trend to replace the nondegradable plastic commodities with biodegradable ones, it is necessary to evaluate whether biodegradable plastics and the generated microplastics would alleviate plastic pollution or induce greater ecological impacts.

Solid-phase microextraction combined with gas chromatography/triple quadrupole tandem mass spectrometry for determination of nitrated polycyclic aromatic hydrocarbons in sediments.

Nitro-polycyclic aromatic hydrocarbons have been detected in various environmental media. However, determination in sediment matrix is challenging due to the lack of a suitable method. In this study, a reliable method for determining 15 nitro-polycyclic aromatic hydrocarbons in sediments was developed based on accelerated solvent extraction and solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry. The accelerated solvent extraction and solid-phase microextraction are sample pre-treatment techniques that have advantages, such as rapid operation and minimal sample volume. Initially, the solid-phase microextraction was optimized using five commercial fibers and from that 65 µm polydimethylsiloxane/divinylbenzene fiber was selected as the best fiber. Further, the accelerated solvent extraction conditions were optimized by Taguchi experimental design, such as extraction temperature (120℃), extraction solvent (dichloromethane), number of cycles (two), static extraction period (4 min), and rinse volume (90%). The method parameters, such as limits of quantitation, and intraday and interday accuracy and precision, were in the range of 0.067-1.57 ng/g, 75.2-115.2%, 69.9-115.4%, and 1.0-16.5%, respectively. Upon meeting all the quality criteria, the method was applied successfully to analyze real sediment samples. Therefore, our study creates a new prospect for the future application of direct immersion solid-phase microextraction in sediment analysis.

Dissolution of Fe from Fe-bearing minerals during the brown-carbonization processes in atmosphere.

Previous studies found Fe dissolution in atmosphere correlates to biomass burning, while the underlying mechanisms need to be further investigated. In this study, we reported a laboratory investigation about Fe dissolution behavior of two model Fe-bearing clay minerals of montmorillonite (SWy-2) and illite (IMt-2), and one standard mineral dust of Arizona test dust (AZTD) in atmospheric condition (pH = 2), after the minerals engaging into the brown-carbonization reaction with guaiacol, which is a commonly detected volatile phenol substance in biomass burning. The results show that the pre-brown-carbonization reaction promoted Fe dissolution from all the three minerals, attributing to the reduction of Fe(III) by gaseous guaiacol. The Fe dissolution from SWy-2, IMt-2 and AZTD were also compared under both light and dark conditions to simulate the daytime and nighttime atmospheric processes. As a result, model solar irradiation further promoted Fe dissolution from IMt-2 and AZTD, since both minerals contain moderate photo-reducible Fe(III) oxide or/and Fe(III) oxyhydroxide. The promotive effect of solar irradiation on Fe dissolution from AZTD would be gradually diminished because the photo-reactive Fe(III) is also guaiacol-reducible. Whereas, it was on the contrary for SWy-2 which does not contain the Fe(III) (oxyhydr-)oxide phase. And more dependently, the photo-induced hydroxyl radical (OH) on SWy-2 would re-oxidize the formed Fe(II), unless sufficient amount of guaiacol or brown-carbonization products on SWy-2 consumed the OH and complexed with surface coordinated Fe(III) forming photo-reducible Fe(III). The results of this study suggested the brown carbonization process on minerals would greatly mediate the Fe dissolution behavior from the Fe-bearing mineral dusts in atmosphere. Similar processes might need to be taken into consideration to accurately evaluate the input of Fe from atmosphere to open oceans.

Airborne Microplastics: A Review on the Occurrence, Migration and Risks to Humans.

As emerging environmental contaminants, microplastics may cause potential hazard to global ecosphere (including water, soil and air) and human health. To date, the occurance and ecological effects of microplastics in water and soil were systematically summarized. However, there are few reviews of microplastics in air (i.e. airborne microplastics). Recently, microplastics have been observed in atmospheric fallout collected from some areas. Although the studies are limited, most of the researches showed that synthetic textiles are the main source of airborne microplastics, and fibers are the dominant shape. Airborne microplastics are contributors to microplastic pollution in aquatic and soil environments. In addition, airborne microplastics can be directly inhaled and posed health risks to humans. Therefore, this review summarized the current knowledge and provide insights into further research to better understand airborne microplastics and their risks to human.

Enhanced alteration of poly(vinyl chloride) microplastics by hydrated electrons derived from indole-3-acetic acid assisted by a common cationic surfactant.

In this study, a new photo-irradiated reductive dechlorination pathway and the underlying transformation mechanism are described for poly(vinyl chloride) microplastics (PVC-MPs). PVC-MPs underwent photo-reductive dechlorination process with the release of chloride ions. This reaction could be facilitated in the presence of indole-3-acetic acid (IAA) and hexadecyltrimethylammonium bromide (CTAB) under neutral pH and simulated sunlight irradiation conditions. Electrostatic interaction between IAA and CTAB produced neutral IAA/CTAB complex, which might account for the enhanced adsorption of IAA on PVC powders. Upon photo-irradiation, the adsorbed IAA was excited to generate hydrated electrons (eaq-), which could pass through a shorter distance to PVC-MP surface than that derived from homogeneous IAA molecules in aqueous solution. Transient spectra of laser flash photolysis provided direct evidence for the generation of eaq-, which supported the proposed dechlorination mechanism. Based on the results of attenuated total reflectance/Fourier transform infrared (ATR/FTIR) and Raman spectra, C-Cl bond cleavage and polyene formation were involved in the structural transformation of PVC-MPs. Due to the hydrophobic effects and π-π interactions between aromatic rings and polyene structures in PVC-MP surface, the PVC-MP powders irradiated in the presence of IAA/CTAB showed an enhanced sorption for both hydrophobic and hydrophilic aromatic chemicals.

N-Hydroxy sulfonamides as new sulfenylating agents for the functionalization of aromatic compounds.

An unprecedented use of N-hydroxy sulfonamides as sulfenylating agents has been established. In the presence of catalytic amounts of iodine and N-hydroxysuccinimide, N-hydroxy sulfonamides participated in sulfenylation with indoles, 7-azaindole, N-methyl pyrrole, and 2-naphthol to afford structurally diverse thioethers in moderate to excellent yields with very high regioselectivity.