Polybromodiphenyl ethers(PBDEs),the widely used flame retardants,are common contaminants in surface soils at e-waste recycling sites.The association of PBDEs with soil colloids has been observed,indicating the potenti...Polybromodiphenyl ethers(PBDEs),the widely used flame retardants,are common contaminants in surface soils at e-waste recycling sites.The association of PBDEs with soil colloids has been observed,indicating the potential risk to groundwater due to colloid-facilitated transport.However,the extent to which soil colloidsmay enhance the spreading of PBDEs in groundwater is largely unknown.Herein,we report the co-transport of decabromodiphenyl ester(BDE-209)and soil colloids in saturated porous media.The colloids released froma soil sample collected at an e-waste recycling site in Tianjin,China,contain high concentration of PBDEs,with BDE-209 being the most abundant conger(320±30 mg/kg).The colloids exhibit relatively high mobility in saturated sand columns,under conditions commonly observed in groundwater environments.Notably,under all the tested conditions(i.e.,varying flow velocity,pH,ionic species and ionic strength),the mass of eluted BDE-209 correlates linearly with that of eluted soil colloids,even though the mobility of the colloids varies markedly depending on the specific hydrodynamic and solution chemistry conditions involved.Additionally,the mass of BDE-209 retained in the columns also correlates strongly with themass of retained colloids.Apparently,the PBDEs remain bound to soil colloids during transport in porous media.Findings in this study indicate that soil colloidsmay significantly promote the transport of PBDEs in groundwater by serving as an effective carrier.This might be the reason why the highly insoluble and adsorptive PBDEs are found in groundwater at some PBDE-contaminated sites.展开更多
The separation of lithium isotopes (^(6)Li and ^(7)Li) is of great importance for the nuclear industry.The lithium amalgam method is the only lithium isotopes separation process in industry,and the extensive use of me...The separation of lithium isotopes (^(6)Li and ^(7)Li) is of great importance for the nuclear industry.The lithium amalgam method is the only lithium isotopes separation process in industry,and the extensive use of mercury has raised concerns about its potential environmental hazards,which have prompted the search for more efficient and environmentally friendly alternatives.Crown ethers can bind lithium ions highly selectively and separate lithium isotopes effectively.A chemical exchange-based lithium isotopes separation method using crown ether decorated materials could be a viable and cost-effective alternative to the lithium amalgam method.In this review,we provide a systematic summary of the recent advances in lithium isotopes separation using crown ethers decorated materials.展开更多
Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold i...Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold is significant.Herein we disclose a chiral N,N’-dioxide/Lewis acid complex-catalyzed asymmetric inverse-electron-demand Diels-Alder(IEDDA)reaction using electron-deficient 3-carboalkoxyl-2-pyrones and less electron-enriched aryl enol ethers as reactants.A wide range of non-and 1,2-disubstituted acyclic aryl enol ethers are applicable to deliver diverse chiral bridged bicyclic lactones in high yields and stereoselectivities(up to 96%yield,>20:1 dr,97:3 er).The bridged bicyclic lactone core can be easily converted into chiral aryl cyclohex-3-en ether scaffold.Notably,DFT calculations revealed a stepwise and endo mechanism to explain the high enantioselectivity controlled by the cooperative effect of the steric factors and the dispersion interactions between ligands and enol ethers.展开更多
A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on...A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on NaHSO4.H2O under solvent-free conditions is reported.展开更多
A series of novel crown aldoxime ethers were synthesized,demonstrating notable thermal and hydrolysis stability.The showcased acid-catalyzed and photo-induced cis/trans isomerization,which enables orthogonal control o...A series of novel crown aldoxime ethers were synthesized,demonstrating notable thermal and hydrolysis stability.The showcased acid-catalyzed and photo-induced cis/trans isomerization,which enables orthogonal control over both vip complexation and the chiroptical effects of these crown aldoxime ethers,manifesting a regulation of complexation through isomerization at binding heteroatoms.展开更多
Polyoxymethylene dimethyl ethers(PODE)were synthesized from the reaction of paraformaldehyde with dimethoxymethane(DMM)over different acid catalysts at different conditions.Products were found to follow the Schulz-Flo...Polyoxymethylene dimethyl ethers(PODE)were synthesized from the reaction of paraformaldehyde with dimethoxymethane(DMM)over different acid catalysts at different conditions.Products were found to follow the Schulz-Flory distribution law.The chain propagation proceeds through the insertion of an individual segment of CH2O one by one,while the simultaneous insertion of a few CH2O segments or their assembly is unlikely.Due to the restriction of this law,it is difficult to increase the selectivity to the desired products(e.g.,PODE3 4).展开更多
Nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river （Fuhe River） in North China were analyzed for polybrominated diphenyl ethers （PBDEs） and decabromodiphenylethane （DBDPE）....Nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river （Fuhe River） in North China were analyzed for polybrominated diphenyl ethers （PBDEs） and decabromodiphenylethane （DBDPE）. The concentrations of PBDEs and DBDPE in sediments ranged from 5.5 to 300.7 ng/g dry weight （dw） and 1.1 to 68.2 ng/g dw, respectively. Their levels in sediments in Fuhe River were significantly higher than those in Balyandian Lake. Compared to data from other regions, the PBDE levels in surface sediments from Baiyangdian Lake and Fuhe River were in the medium to lower range. Among the PBDE congeners, BDE209 was predominant, with contributions to the total PBDEs ranging from 79.4% to 97.3% in sediment samples. For the lowly brominated congeners （tri- to hepta-BDE）, BDE47 and BDE99 were the most abundant, which contributed 52.1% and 44.1% to the sum of tri- to hepta-BDEs in the sediments from Baiyangdian Lake and Fuhe River, respectively. The compositional patterns of PBDEs in Baiyangdian Lake sediments indicated that technical deca-BDE mixture was the major pollutant sources with a minor contribution of penta-BDE mixture. The present study suggested that the importance of Fuhe River as a possibly potential sources of PBDEs contamination in Baiyangdian Lake.展开更多
Accelerated industrialization and urbanization,and unregulated disposal of waste of electric and electronic equipment（e-waste） in China have caused environmental pollution of brominated flame retardants（BFRs）.This...Accelerated industrialization and urbanization,and unregulated disposal of waste of electric and electronic equipment（e-waste） in China have caused environmental pollution of brominated flame retardants（BFRs）.This review summarized the levels,trends,and bioaccumulation characteristics of polybrominated diphenyl ethers（PBDEs） and other potential alternative BFRs including hexabromocyclododecanes（HBCDs）,1,2-bis（2,4,6-dibromophenoxy） ethane（BTBPE） and decabromodiphenylethane（DBDPE） in wildlife from China.PBDE levels in wildlife from China were generally higher than those from other parts in Asia,and were comparable to those from Europe but were lower than those from North America.However,wildlife from the e-waste recycling sites in South China and East China contained much higher PBDEs compared to other reports around the world,suggesting the heavy contamination of PBDEs in these regions.The alternative BFRs were also detected in wildlife,revealing that the animals are exposed to these chemicals,in addition to PBDEs.Temporal trends indicated by levels in marine mammals from South China suggested that PBDE levels increased from the beginning of 1990s to 2000s,but decreased from the middle of 2000s,followed by relatively steady levels.In contrast,HBCDs were found to be continuously increasing from 1997 to 2007,indicating the increasing usage of HBCDs in China in recent years.Compared to PBDE profiles found in other parts,aquatic species and birds from China contained relatively higher contributions of BDE28 and 209,respectively,suggesting the possible different usage pattern of PBDEs.Future works including keeping monitoring at a reasonable scale and frequency to make sure levels near urban centers indicative of population do not increase are needed.Additionally,focus effort on e-waste recycling regions to look for impacts and to determine if regulation/controls are resulting in lower environmental contamination,and incorporation of sentinel species in monitoring efforts are recommended.展开更多
Polybrominated diphenyl ethers （PBDEs） were measured in atmosphere and soil samples taken in winter and summer at a PBDE production area of Laizhou Bay in China. The concentrations of ∑11PBDE were 0.017-1.17 ng/m3 ...Polybrominated diphenyl ethers （PBDEs） were measured in atmosphere and soil samples taken in winter and summer at a PBDE production area of Laizhou Bay in China. The concentrations of ∑11PBDE were 0.017-1.17 ng/m3 in gaseous phase, 0.5-161.1 ng/m3 in particulate phase, and 73-2629 ng/g dry weight in soil samples. The PBDE congener pattern in the gaseous phase differed from that in the particulate phase, and the PBDE congener pattern in the particulate phase was similar with that in soil. This demonstrated that there was little difference with atmospheric particle-soil transfer efficiency among PBDE congeners. In addition, there were seasonal variations in percentages on particle for lower brominated congeners. The BDE-28 was mostly in the gaseous phase in summer （88.3%）, whereas the average proportion of BDE-28 in gaseous phase in winter was 38.9%. Higher brominated congeners （i.e., BDE-206, BDE- 207, BDE-208, and BDE-209） were bound to the atmospheric particulate phase, and their potentials for long-range migration were mainly affected by the environmental behavior of atmospheric particles. Results indicated that PBDE congeners in summer were closer to gas-particle partition equilibrium than in winter. Temperature should be considered the main factor causing nonequilibrium in winter.展开更多
The chemical equilibrium and reaction kinetic behavior in the synthesis of polyoxymethylene dimethyl ethers （DMMn） were investigated over sulfated titania in order to reveal the decisive factor controlling the react...The chemical equilibrium and reaction kinetic behavior in the synthesis of polyoxymethylene dimethyl ethers （DMMn） were investigated over sulfated titania in order to reveal the decisive factor controlling the reaction. The results showed that the molar ratio of adjacent DMMn products in equilibrium solution had the same value, which depended absolutely on the reaction temperature. Meanwhile, the reactions had the same DMMn products distributions under varied reaction conditions. The equilibrium constants of the related step-wise reactions for DMMn formation were equal, which were calculated based on the bulk compositions of the reaction solution. And thus, the selectivity to DMMn was mainly controlled by the chemical equilibrium, i.e., thermodynamic control. In brief, the present results provide some guidance for future synthesis of DMMn.展开更多
The levels and distributions of polybrominated diphenyl ethers （PBDEs） in chicken tissues from an electronic waste （e-waste） recycling area in southeast China were investigated. Human dietary intake by local resid...The levels and distributions of polybrominated diphenyl ethers （PBDEs） in chicken tissues from an electronic waste （e-waste） recycling area in southeast China were investigated. Human dietary intake by local residents via chicken muscle and eggs was estimated. The mean PBDEs concentrations in tissues ranged from 15.2 to 3138.1 ng/g lipid weight （lw） and in egg the concentration was 563.5 ng/g lw. The results showed that the level of total PBDEs （∑PBDEs） in the chicken tissue was 2-3 orders of magnitude higher than those reported in the literature. The large difference of ∑PBDEs concentrations between tissues confirmed that the distribution of PBDEs in tissues depend on tissue-specificity rather than the ＂lipid-compartment＂. BDE-209 was the predominant congener （82.5%- 94.7% of ∑PBDEs） in all chicken tissues except in brain （34.7% of ∑PBDEs）, which indicated that deca-BDE （the major commercial PBDE formulation comprising 65%-70% of total production） was major pollution source in this area and could be bioaccumulated in terrestrial animals. The dietary PBDEs intake of the local residents from chicken muscle and egg, assuming only local bred chickens and eggs were consumed, ranged from 2.2 to 22.5 ng/（day.kg body weight （bw）） with a mean value of 13.5 ng/（day-kg bw）, which was one order of magnitude higher than the value reported in previous studies for consumption of all foodstuffs.展开更多
Areas containing industrial facilities belonging to three different typical industries that may cause pollution by polybrominated diphenyl ethers （PBDEs） in Beijing, China were investigated. Specifically, the areas ...Areas containing industrial facilities belonging to three different typical industries that may cause pollution by polybrominated diphenyl ethers （PBDEs） in Beijing, China were investigated. Specifically, the areas contained a solid waste incineration plant, a chemical factory, and a heat and power plant. Investigation of the pollution status of PBDEs in the surface soil from areas around these industries revealed the highest concentration of 42 PBDE congeners （118 ng/g, dry mass） at the solid waste incineration plant. In the other two plants, the highest concentrations were both 26 ng/g （dry mass）. Among the PBDE homologues, the PBDE contamination at all sites showed similar congener compositions, with BDE 209 being the dominant congener. Our findings established the first contamination status of three typical industrial areas in Beijing. Furthermore, the total concentrations of 42 PBDE congeners tended to decrease as the distance from the investigated plants increased. Overall, these plants were identified as potential pollution sources of PBDEs in Beijing. Moreover, Pearson correlation analysis revealed that the major PBDE source in Beijing may be associated with the technical deca-BDE and penta-BDE mixture. Based on the data obtained in this preliminary investigation, further study of the potential of these sources to emit PBDEs in Beijing is warranted.展开更多
To understand potential ecotoxicological effects of electrical and electronic equipment waste （e-waste） recycling and polybrominated diphenyl ethers （PBDEs） bioaccumulation in loaches, a semi-field experiment usin...To understand potential ecotoxicological effects of electrical and electronic equipment waste （e-waste） recycling and polybrominated diphenyl ethers （PBDEs） bioaccumulation in loaches, a semi-field experiment using Chinese loach （Misgurnus anguiUicaudatus） as experimental fish was performed. Larval loaches were kept in net-cage for three months in an e-wastes recycling site and a reference site in Southeastern China. There was significant difference of the survival rate between the loaches from the e-wastes recycling site （27%, 19/70） and from reference site （70%, 49/70）. Histopathological responses were also found in all the livers examined in loaches from the e-wastes recycling site. These results showed that mixed pollutants resulted from e-wastes recycling led to ecotoxicological effects on loaches. The bioaccumulation of polybrominated diphenyl ethers （PBDEs）, the main pollutants in e-waste, in loaches was also studied, the mean concentration of total PBDEs in sediment was 6726.17 ng/g wet weight and in water samples was 4.08 ng/L （dissolved phase）. BDE 209 was the dominant congener in sediment and with relatively high concentration in water. Relatively low concentration of BDE 209 （less than 0.01% of total PBDEs） and high concentration of BDE47 （up to 39.34% of total PBDEs） were detected in loaches.展开更多
Uptake, translocation and debromination of three polybrominated diphenyl ethers （PBDEs）, BDE-28, -47 and -99, in maize were studied in a hydroponic experiment. Roots took up most of the PBDEs in the culture solution...Uptake, translocation and debromination of three polybrominated diphenyl ethers （PBDEs）, BDE-28, -47 and -99, in maize were studied in a hydroponic experiment. Roots took up most of the PBDEs in the culture solutions and more highly brominated PBDEs had a stronger uptake capability. PBDEs were detected in the stems and leaves of maize after exposure but rarely detected in the blank control plants. Furthermore, PBDE concentrations decreased from roots to stems and then to leaves, and a very clear decreasing gradient was found in segments upwards along the stem. These altogether provide substantiating evidence for the acropetal translocation of PBDEs in maize. More highly brominated PBDEs were translocated with more difficulty. Radial translocation of PBDEs from nodes to sheath inside maize was also observed. Both acropetal and radial translocations were enhanced at higher transpiration rates, suggesting that PBDE transport was probably driven by the transpiration stream. Debromination of PBDEs occurred in all parts of the maize, and debromination patterns of different parent PBDEs and in different parts of a plant were similar but with some differences. This study for the first time provides direct evidence for the acropetal translocation of PBDEs within plants, elucidates the process of PBDE transport and clarifies the debromination products of PBDEs in maize.展开更多
Polyoxymethylene dimethyl ethers(DMM_n) are promising diesel additives. The synthesis of DMM_n from methylal(DMM) and paraformaldehyde over the NKC-9 acidic ion-exchange resin catalyst was investigated. Many unrecycla...Polyoxymethylene dimethyl ethers(DMM_n) are promising diesel additives. The synthesis of DMM_n from methylal(DMM) and paraformaldehyde over the NKC-9 acidic ion-exchange resin catalyst was investigated. Many unrecyclable by-products such as methyl formate, dimethyl ether and formic acid were produced in the reaction. To increase the selectivity of the desired products DMM_(3-6) and reduce the amount of unrecyclable by-products, the effects of reaction temperature, time, pressure and the molar ratio of the raw materials were evaluated through a series of single factor experiments. Experiments revealed that trace amount of water could suppress the formation of unrecyclable by-products, and the optimum initial water content(less than 2 wt%) was investigated. In addition, the synthetic process needs to go through the polyoxymethylene hemiformals intermediate stage, and then the DMM_n were obtained when polyoxymethylene hemiformals reacted with methanol. Ultimately, a possible mechanism is proposed to describe the formation of DMM_n from polyoxymethylene hemiformals in detail, in which it is revealed that the formation of carbocation intermediates is important in the reaction processes.展开更多
Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 hal...Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 halogenated anisoles at the HF/6-31 G^＊ level. A number of statistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time （RRT） and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials （ESPs） together with the molecular volume （Vmc） could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.展开更多
Electrolyte engineering is considered as an effective strategy to establish stable solid electrolyte interface(SEI),and thus to suppress the growth of lithium dendrites.In a recent study reported in Advanced Functiona...Electrolyte engineering is considered as an effective strategy to establish stable solid electrolyte interface(SEI),and thus to suppress the growth of lithium dendrites.In a recent study reported in Advanced Functional Materials by Ma group,discovered that strong coordination force could be founded between 15-Crown-5 ether(15-C-5) and Li+,which facilitates the crown ether(15-C-1) to participate in the solvation structure of Li+ in the electrolyte for the same purpose.Such a novel strategy might impact the design of highperformance and safe lithium metal batteries(LMB s).展开更多
We measured 39 polybrominated diphenyl ethers （PBDEs） in the muscle tissue of three species of fish （Sciaenops ocellatus,Sparus macrocephalus,and Lateolabrax japonicus） and four species of shellfish （Tegillarca g...We measured 39 polybrominated diphenyl ethers （PBDEs） in the muscle tissue of three species of fish （Sciaenops ocellatus,Sparus macrocephalus,and Lateolabrax japonicus） and four species of shellfish （Tegillarca granosa,Cyclina sinensis,Sinonovacula constricta,and Ostrea cucullata） that were collected downstream of electronic-waste recycling plants in Taizhou,China.A total of 24 PBDE congeners （PBDE 24） in the samples were detected.The PBDE 24 （total PBDE） ranged from 545.4 to 1688.7 ng/kg ww （wet weight）.The mean PBDE 24 concentration was 1382.6 ng/kg ww in fish and 858.1 ng/kg ww in shellfish.The lower brominated congeners were detected at relatively high concentrations in all species.The penta-products,produced from e-waste,were found at relatively low levels.A principal component analysis suggested a significant correlation among di-,tri-,tetra-,and hepta-BDEs for the three species of fish.Similarly,we found a significant correlation between mono-and tri-BDEs in the shellfish.Our results suggested that the processes of PBDE metabolism and elimination were similar in both fish and shellfish.In addition,the primary source of PBDEs appeared to be from the debromination of high brominated PBDEs.展开更多
This study describes the development and validation of a sensitive and reliable method for determination of polybrominated diphenyl ethers（PBDEs）in atmospheric particulate matter using selective pressurized liquid e...This study describes the development and validation of a sensitive and reliable method for determination of polybrominated diphenyl ethers（PBDEs）in atmospheric particulate matter using selective pressurized liquid extraction（SPLE）and gas chromatography–mass spectrometry with a negative chemical ionization（GC-NCI-MS）.Extraction and clean-up were performed using PLE with 2 g florisil and 3 g silica placed in the extraction cells.Under optimal conditions,14 PBDEs were extracted at 70℃ using hexane/dichloromethane（50：50,v/v）as solvent.Validation of SPLE returned excellent recoveries for most analytes,with relative standard deviations mostly below20%.Method detection limits ranged from 0.13 to15.38 ng·mL^-1 for the GC-MS analyses.The method was successfully applied to atmospheric particulate matter of Beijing,where analytes were detected in the range of182.79 to 468.99 pg·m^-3.展开更多
Four cellulose ethers（CEs） were compared for their effects on the pore structure of cement paste using mercury intrusion porosimetry. The experimental results show that the total pore volume and porosity of cement p...Four cellulose ethers（CEs） were compared for their effects on the pore structure of cement paste using mercury intrusion porosimetry. The experimental results show that the total pore volume and porosity of cement pastes containing the four cellulose ethers are significantly higher than that of the pure cement pastes and the total pore volume and porosity of cement pastes containing HEC（hydroxyethyl cellulose ether） or low viscosity cellulose ethers are low in four CEs. By changing the surface tension and viscosity of liquid phase and the strengthening of liquid film between air voids in cement pastes, CEs affect the formation, diameter evolution and upward movement of air voids and the pore structure of hardening cement paste. For the four CEs, the pore volume of cement pastes containing HEC or low viscosity cellulose ethers is higher with the diameter of 30-70 nm while lower with the diameter larger than 70 nm. CEs affect the pore structure of cement paste mainly through their effects on the evolvement of the small air voids into bigger ones when the pore diameter is below 70 nm and their effects on the entrainment and stabilization of air voids when the pore diameter is above 70 nm.展开更多
基金supported by the National Key Research and Development Program of China(No.2019YFC1804202)the National Natural Science Foundation of China(No.22020102004)+1 种基金the Tianjin Municipal Science and Technology Bureau(No.21JCZDJC00280)the Fundamental Research Funds for the Central Universities by the Ministry of Education of China(No.T2017002).
文摘Polybromodiphenyl ethers(PBDEs),the widely used flame retardants,are common contaminants in surface soils at e-waste recycling sites.The association of PBDEs with soil colloids has been observed,indicating the potential risk to groundwater due to colloid-facilitated transport.However,the extent to which soil colloidsmay enhance the spreading of PBDEs in groundwater is largely unknown.Herein,we report the co-transport of decabromodiphenyl ester(BDE-209)and soil colloids in saturated porous media.The colloids released froma soil sample collected at an e-waste recycling site in Tianjin,China,contain high concentration of PBDEs,with BDE-209 being the most abundant conger(320±30 mg/kg).The colloids exhibit relatively high mobility in saturated sand columns,under conditions commonly observed in groundwater environments.Notably,under all the tested conditions(i.e.,varying flow velocity,pH,ionic species and ionic strength),the mass of eluted BDE-209 correlates linearly with that of eluted soil colloids,even though the mobility of the colloids varies markedly depending on the specific hydrodynamic and solution chemistry conditions involved.Additionally,the mass of BDE-209 retained in the columns also correlates strongly with themass of retained colloids.Apparently,the PBDEs remain bound to soil colloids during transport in porous media.Findings in this study indicate that soil colloidsmay significantly promote the transport of PBDEs in groundwater by serving as an effective carrier.This might be the reason why the highly insoluble and adsorptive PBDEs are found in groundwater at some PBDE-contaminated sites.
基金support from the National Natural Science Foundation of China (Grant No.U21B2094 and Grant No.U2067212)。
文摘The separation of lithium isotopes (^(6)Li and ^(7)Li) is of great importance for the nuclear industry.The lithium amalgam method is the only lithium isotopes separation process in industry,and the extensive use of mercury has raised concerns about its potential environmental hazards,which have prompted the search for more efficient and environmentally friendly alternatives.Crown ethers can bind lithium ions highly selectively and separate lithium isotopes effectively.A chemical exchange-based lithium isotopes separation method using crown ether decorated materials could be a viable and cost-effective alternative to the lithium amalgam method.In this review,we provide a systematic summary of the recent advances in lithium isotopes separation using crown ethers decorated materials.
基金National Natural Science Foundation of China(Nos.22001177,22203023)Guangdong Pearl River Talent Program(no.2021QN020268)+3 种基金the Natural Science Foundation of Guangdong Province(Nos.2024A1515012381,2022A1515011859)Shenzhen Bay Laboratory Startup Fund(No.S201100003)Major Program of Shenzhen Bay Laboratory(No.S211101001-4)Shenzhen Bay Qihang Fellow Program(No.QH23001)for generous financial support.
文摘Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold is significant.Herein we disclose a chiral N,N’-dioxide/Lewis acid complex-catalyzed asymmetric inverse-electron-demand Diels-Alder(IEDDA)reaction using electron-deficient 3-carboalkoxyl-2-pyrones and less electron-enriched aryl enol ethers as reactants.A wide range of non-and 1,2-disubstituted acyclic aryl enol ethers are applicable to deliver diverse chiral bridged bicyclic lactones in high yields and stereoselectivities(up to 96%yield,>20:1 dr,97:3 er).The bridged bicyclic lactone core can be easily converted into chiral aryl cyclohex-3-en ether scaffold.Notably,DFT calculations revealed a stepwise and endo mechanism to explain the high enantioselectivity controlled by the cooperative effect of the steric factors and the dispersion interactions between ligands and enol ethers.
文摘A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on NaHSO4.H2O under solvent-free conditions is reported.
基金support of the National Natural Science Foundation of China (Nos.22271201,92056116,22171194,22201194)the Science & Technology Department of Sichuan Province (Nos.2022YFH0095 and 2021ZYD0052)the Fundamental Research Funds for the Central Universities (No.20826041D4117)。
文摘A series of novel crown aldoxime ethers were synthesized,demonstrating notable thermal and hydrolysis stability.The showcased acid-catalyzed and photo-induced cis/trans isomerization,which enables orthogonal control over both vip complexation and the chiroptical effects of these crown aldoxime ethers,manifesting a regulation of complexation through isomerization at binding heteroatoms.
文摘Polyoxymethylene dimethyl ethers(PODE)were synthesized from the reaction of paraformaldehyde with dimethoxymethane(DMM)over different acid catalysts at different conditions.Products were found to follow the Schulz-Flory distribution law.The chain propagation proceeds through the insertion of an individual segment of CH2O one by one,while the simultaneous insertion of a few CH2O segments or their assembly is unlikely.Due to the restriction of this law,it is difficult to increase the selectivity to the desired products(e.g.,PODE3 4).
基金supported by the National Basic Research Program(973) of China(No. 2006CB403306)the National Natural Science Foundation of China(No.30870311)
文摘Nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river （Fuhe River） in North China were analyzed for polybrominated diphenyl ethers （PBDEs） and decabromodiphenylethane （DBDPE）. The concentrations of PBDEs and DBDPE in sediments ranged from 5.5 to 300.7 ng/g dry weight （dw） and 1.1 to 68.2 ng/g dw, respectively. Their levels in sediments in Fuhe River were significantly higher than those in Balyandian Lake. Compared to data from other regions, the PBDE levels in surface sediments from Baiyangdian Lake and Fuhe River were in the medium to lower range. Among the PBDE congeners, BDE209 was predominant, with contributions to the total PBDEs ranging from 79.4% to 97.3% in sediment samples. For the lowly brominated congeners （tri- to hepta-BDE）, BDE47 and BDE99 were the most abundant, which contributed 52.1% and 44.1% to the sum of tri- to hepta-BDEs in the sediments from Baiyangdian Lake and Fuhe River, respectively. The compositional patterns of PBDEs in Baiyangdian Lake sediments indicated that technical deca-BDE mixture was the major pollutant sources with a minor contribution of penta-BDE mixture. The present study suggested that the importance of Fuhe River as a possibly potential sources of PBDEs contamination in Baiyangdian Lake.
基金supported by the National Natural Science Foundation of China (No. 41103054,40821003,41073081)the Earmarked Fund of the State Key Laboratory of Organic Geochemistry (No. OGL-200905)
文摘Accelerated industrialization and urbanization,and unregulated disposal of waste of electric and electronic equipment（e-waste） in China have caused environmental pollution of brominated flame retardants（BFRs）.This review summarized the levels,trends,and bioaccumulation characteristics of polybrominated diphenyl ethers（PBDEs） and other potential alternative BFRs including hexabromocyclododecanes（HBCDs）,1,2-bis（2,4,6-dibromophenoxy） ethane（BTBPE） and decabromodiphenylethane（DBDPE） in wildlife from China.PBDE levels in wildlife from China were generally higher than those from other parts in Asia,and were comparable to those from Europe but were lower than those from North America.However,wildlife from the e-waste recycling sites in South China and East China contained much higher PBDEs compared to other reports around the world,suggesting the heavy contamination of PBDEs in these regions.The alternative BFRs were also detected in wildlife,revealing that the animals are exposed to these chemicals,in addition to PBDEs.Temporal trends indicated by levels in marine mammals from South China suggested that PBDE levels increased from the beginning of 1990s to 2000s,but decreased from the middle of 2000s,followed by relatively steady levels.In contrast,HBCDs were found to be continuously increasing from 1997 to 2007,indicating the increasing usage of HBCDs in China in recent years.Compared to PBDE profiles found in other parts,aquatic species and birds from China contained relatively higher contributions of BDE28 and 209,respectively,suggesting the possible different usage pattern of PBDEs.Future works including keeping monitoring at a reasonable scale and frequency to make sure levels near urban centers indicative of population do not increase are needed.Additionally,focus effort on e-waste recycling regions to look for impacts and to determine if regulation/controls are resulting in lower environmental contamination,and incorporation of sentinel species in monitoring efforts are recommended.
基金supported by the National Natural Science Foundation of China (No. 20507023)the 985 Project of Minzu University of China (No. CUN985-3-3)the 111 Project of Minzu University of China (No. B08044)
文摘Polybrominated diphenyl ethers （PBDEs） were measured in atmosphere and soil samples taken in winter and summer at a PBDE production area of Laizhou Bay in China. The concentrations of ∑11PBDE were 0.017-1.17 ng/m3 in gaseous phase, 0.5-161.1 ng/m3 in particulate phase, and 73-2629 ng/g dry weight in soil samples. The PBDE congener pattern in the gaseous phase differed from that in the particulate phase, and the PBDE congener pattern in the particulate phase was similar with that in soil. This demonstrated that there was little difference with atmospheric particle-soil transfer efficiency among PBDE congeners. In addition, there were seasonal variations in percentages on particle for lower brominated congeners. The BDE-28 was mostly in the gaseous phase in summer （88.3%）, whereas the average proportion of BDE-28 in gaseous phase in winter was 38.9%. Higher brominated congeners （i.e., BDE-206, BDE- 207, BDE-208, and BDE-209） were bound to the atmospheric particulate phase, and their potentials for long-range migration were mainly affected by the environmental behavior of atmospheric particles. Results indicated that PBDE congeners in summer were closer to gas-particle partition equilibrium than in winter. Temperature should be considered the main factor causing nonequilibrium in winter.
基金supported by the National Natural Science Foundation of China(NSFC,No.21203220 and 21133011)China Postdoctoral Science Foundation(No.2014M551674)+1 种基金Jiangsu Planned Projects for Postdoctoral Research Funds(No.1302070C)the National Basic Research Program of China(973 Program,No.2011CB201404)
文摘The chemical equilibrium and reaction kinetic behavior in the synthesis of polyoxymethylene dimethyl ethers （DMMn） were investigated over sulfated titania in order to reveal the decisive factor controlling the reaction. The results showed that the molar ratio of adjacent DMMn products in equilibrium solution had the same value, which depended absolutely on the reaction temperature. Meanwhile, the reactions had the same DMMn products distributions under varied reaction conditions. The equilibrium constants of the related step-wise reactions for DMMn formation were equal, which were calculated based on the bulk compositions of the reaction solution. And thus, the selectivity to DMMn was mainly controlled by the chemical equilibrium, i.e., thermodynamic control. In brief, the present results provide some guidance for future synthesis of DMMn.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-YW-420-3,KZCX2-YW-Q-02-05)the National Natural Science Foundation of China (No.20437020,20677074)
文摘The levels and distributions of polybrominated diphenyl ethers （PBDEs） in chicken tissues from an electronic waste （e-waste） recycling area in southeast China were investigated. Human dietary intake by local residents via chicken muscle and eggs was estimated. The mean PBDEs concentrations in tissues ranged from 15.2 to 3138.1 ng/g lipid weight （lw） and in egg the concentration was 563.5 ng/g lw. The results showed that the level of total PBDEs （∑PBDEs） in the chicken tissue was 2-3 orders of magnitude higher than those reported in the literature. The large difference of ∑PBDEs concentrations between tissues confirmed that the distribution of PBDEs in tissues depend on tissue-specificity rather than the ＂lipid-compartment＂. BDE-209 was the predominant congener （82.5%- 94.7% of ∑PBDEs） in all chicken tissues except in brain （34.7% of ∑PBDEs）, which indicated that deca-BDE （the major commercial PBDE formulation comprising 65%-70% of total production） was major pollution source in this area and could be bioaccumulated in terrestrial animals. The dietary PBDEs intake of the local residents from chicken muscle and egg, assuming only local bred chickens and eggs were consumed, ranged from 2.2 to 22.5 ng/（day.kg body weight （bw）） with a mean value of 13.5 ng/（day-kg bw）, which was one order of magnitude higher than the value reported in previous studies for consumption of all foodstuffs.
基金supported by the National Natural Science Foundation of China(No.21177148)
文摘Areas containing industrial facilities belonging to three different typical industries that may cause pollution by polybrominated diphenyl ethers （PBDEs） in Beijing, China were investigated. Specifically, the areas contained a solid waste incineration plant, a chemical factory, and a heat and power plant. Investigation of the pollution status of PBDEs in the surface soil from areas around these industries revealed the highest concentration of 42 PBDE congeners （118 ng/g, dry mass） at the solid waste incineration plant. In the other two plants, the highest concentrations were both 26 ng/g （dry mass）. Among the PBDE homologues, the PBDE contamination at all sites showed similar congener compositions, with BDE 209 being the dominant congener. Our findings established the first contamination status of three typical industrial areas in Beijing. Furthermore, the total concentrations of 42 PBDE congeners tended to decrease as the distance from the investigated plants increased. Overall, these plants were identified as potential pollution sources of PBDEs in Beijing. Moreover, Pearson correlation analysis revealed that the major PBDE source in Beijing may be associated with the technical deca-BDE and penta-BDE mixture. Based on the data obtained in this preliminary investigation, further study of the potential of these sources to emit PBDEs in Beijing is warranted.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(No. KZCX2-YW-420-3)the National Basic Research Program (973) of China (No. 2003CB415005)the National Natural Science Foundation of China (No.20437020, 20677074)
文摘To understand potential ecotoxicological effects of electrical and electronic equipment waste （e-waste） recycling and polybrominated diphenyl ethers （PBDEs） bioaccumulation in loaches, a semi-field experiment using Chinese loach （Misgurnus anguiUicaudatus） as experimental fish was performed. Larval loaches were kept in net-cage for three months in an e-wastes recycling site and a reference site in Southeastern China. There was significant difference of the survival rate between the loaches from the e-wastes recycling site （27%, 19/70） and from reference site （70%, 49/70）. Histopathological responses were also found in all the livers examined in loaches from the e-wastes recycling site. These results showed that mixed pollutants resulted from e-wastes recycling led to ecotoxicological effects on loaches. The bioaccumulation of polybrominated diphenyl ethers （PBDEs）, the main pollutants in e-waste, in loaches was also studied, the mean concentration of total PBDEs in sediment was 6726.17 ng/g wet weight and in water samples was 4.08 ng/L （dissolved phase）. BDE 209 was the dominant congener in sediment and with relatively high concentration in water. Relatively low concentration of BDE 209 （less than 0.01% of total PBDEs） and high concentration of BDE47 （up to 39.34% of total PBDEs） were detected in loaches.
基金supported by the National Basic Research Program (973) of China (No. 2009CB421603)the National Natural Science Foundation of China (No.40730740, 20921063, 20807048)
文摘Uptake, translocation and debromination of three polybrominated diphenyl ethers （PBDEs）, BDE-28, -47 and -99, in maize were studied in a hydroponic experiment. Roots took up most of the PBDEs in the culture solutions and more highly brominated PBDEs had a stronger uptake capability. PBDEs were detected in the stems and leaves of maize after exposure but rarely detected in the blank control plants. Furthermore, PBDE concentrations decreased from roots to stems and then to leaves, and a very clear decreasing gradient was found in segments upwards along the stem. These altogether provide substantiating evidence for the acropetal translocation of PBDEs in maize. More highly brominated PBDEs were translocated with more difficulty. Radial translocation of PBDEs from nodes to sheath inside maize was also observed. Both acropetal and radial translocations were enhanced at higher transpiration rates, suggesting that PBDE transport was probably driven by the transpiration stream. Debromination of PBDEs occurred in all parts of the maize, and debromination patterns of different parent PBDEs and in different parts of a plant were similar but with some differences. This study for the first time provides direct evidence for the acropetal translocation of PBDEs within plants, elucidates the process of PBDE transport and clarifies the debromination products of PBDEs in maize.
文摘Polyoxymethylene dimethyl ethers(DMM_n) are promising diesel additives. The synthesis of DMM_n from methylal(DMM) and paraformaldehyde over the NKC-9 acidic ion-exchange resin catalyst was investigated. Many unrecyclable by-products such as methyl formate, dimethyl ether and formic acid were produced in the reaction. To increase the selectivity of the desired products DMM_(3-6) and reduce the amount of unrecyclable by-products, the effects of reaction temperature, time, pressure and the molar ratio of the raw materials were evaluated through a series of single factor experiments. Experiments revealed that trace amount of water could suppress the formation of unrecyclable by-products, and the optimum initial water content(less than 2 wt%) was investigated. In addition, the synthetic process needs to go through the polyoxymethylene hemiformals intermediate stage, and then the DMM_n were obtained when polyoxymethylene hemiformals reacted with methanol. Ultimately, a possible mechanism is proposed to describe the formation of DMM_n from polyoxymethylene hemiformals in detail, in which it is revealed that the formation of carbocation intermediates is important in the reaction processes.
基金This work was supported by the National Natural Science Foundation of China (No. 20502022) and the Ph.D. Fund of Ningbo ( No. 2004A610010)
文摘Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 halogenated anisoles at the HF/6-31 G^＊ level. A number of statistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time （RRT） and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials （ESPs） together with the molecular volume （Vmc） could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.
文摘Electrolyte engineering is considered as an effective strategy to establish stable solid electrolyte interface(SEI),and thus to suppress the growth of lithium dendrites.In a recent study reported in Advanced Functional Materials by Ma group,discovered that strong coordination force could be founded between 15-Crown-5 ether(15-C-5) and Li+,which facilitates the crown ether(15-C-1) to participate in the solvation structure of Li+ in the electrolyte for the same purpose.Such a novel strategy might impact the design of highperformance and safe lithium metal batteries(LMB s).
基金supported by the Wenling Science and Technology Bureau of Zhejiang Province (No. 2007-35)
文摘We measured 39 polybrominated diphenyl ethers （PBDEs） in the muscle tissue of three species of fish （Sciaenops ocellatus,Sparus macrocephalus,and Lateolabrax japonicus） and four species of shellfish （Tegillarca granosa,Cyclina sinensis,Sinonovacula constricta,and Ostrea cucullata） that were collected downstream of electronic-waste recycling plants in Taizhou,China.A total of 24 PBDE congeners （PBDE 24） in the samples were detected.The PBDE 24 （total PBDE） ranged from 545.4 to 1688.7 ng/kg ww （wet weight）.The mean PBDE 24 concentration was 1382.6 ng/kg ww in fish and 858.1 ng/kg ww in shellfish.The lower brominated congeners were detected at relatively high concentrations in all species.The penta-products,produced from e-waste,were found at relatively low levels.A principal component analysis suggested a significant correlation among di-,tri-,tetra-,and hepta-BDEs for the three species of fish.Similarly,we found a significant correlation between mono-and tri-BDEs in the shellfish.Our results suggested that the processes of PBDE metabolism and elimination were similar in both fish and shellfish.In addition,the primary source of PBDEs appeared to be from the debromination of high brominated PBDEs.
基金supported by the National Natural Science Foundation of China(41325010)
文摘This study describes the development and validation of a sensitive and reliable method for determination of polybrominated diphenyl ethers（PBDEs）in atmospheric particulate matter using selective pressurized liquid extraction（SPLE）and gas chromatography–mass spectrometry with a negative chemical ionization（GC-NCI-MS）.Extraction and clean-up were performed using PLE with 2 g florisil and 3 g silica placed in the extraction cells.Under optimal conditions,14 PBDEs were extracted at 70℃ using hexane/dichloromethane（50：50,v/v）as solvent.Validation of SPLE returned excellent recoveries for most analytes,with relative standard deviations mostly below20%.Method detection limits ranged from 0.13 to15.38 ng·mL^-1 for the GC-MS analyses.The method was successfully applied to atmospheric particulate matter of Beijing,where analytes were detected in the range of182.79 to 468.99 pg·m^-3.
基金the National Natural Science Foundation of China(Nos.51461135001 and 51741804)the Natural Science Foundation of Hunan Province,China(No.2017JJ2066)the Scientific Research Project of Education Department,Hunan Province,China(No.17A054)
文摘Four cellulose ethers（CEs） were compared for their effects on the pore structure of cement paste using mercury intrusion porosimetry. The experimental results show that the total pore volume and porosity of cement pastes containing the four cellulose ethers are significantly higher than that of the pure cement pastes and the total pore volume and porosity of cement pastes containing HEC（hydroxyethyl cellulose ether） or low viscosity cellulose ethers are low in four CEs. By changing the surface tension and viscosity of liquid phase and the strengthening of liquid film between air voids in cement pastes, CEs affect the formation, diameter evolution and upward movement of air voids and the pore structure of hardening cement paste. For the four CEs, the pore volume of cement pastes containing HEC or low viscosity cellulose ethers is higher with the diameter of 30-70 nm while lower with the diameter larger than 70 nm. CEs affect the pore structure of cement paste mainly through their effects on the evolvement of the small air voids into bigger ones when the pore diameter is below 70 nm and their effects on the entrainment and stabilization of air voids when the pore diameter is above 70 nm.
