Natural surface coating samples （NSCSs） from the surface of shingles and surficial sediments （SSs） in the Songhua River, China were employed to investigate the relationship between NSCSs and SSs in fractions of he...Natural surface coating samples （NSCSs） from the surface of shingles and surficial sediments （SSs） in the Songhua River, China were employed to investigate the relationship between NSCSs and SSs in fractions of heavy metals （Fe, Mn, Zn, Cu, Pb, and Cd） using the modified sequential extraction procedure （MSEP）. The results show that the differences between NSCSs and SSs in Fe fi＇actions were insignificant and Fe was dominantly present as residual phase （76.22% for NSCSs and 80.88% for SSs） and Fe-oxides phase （20.33% for NSCSs and 16.15% for SSs）. Significant variation of Mn distribution patterns between NSCSs and SSs was observed with Mn in NSCSs mainly present in Mn-oxides phase （48.27%） and that in SSs present as residual phase （45.44%）. Zn, Cu, Pb and Cd were found dominantly in residual fractions （〉48%）, and next in solid oxides/hydroxides for Zn, Pb and Cd and in easily oxidizable solids/compounds form for Cu, respectively. The heavy metal distribution patterns implied that Fe/Mn oxides both in NSCSs and SSs were more important sinks for binding and adsorption of Zn, Pb and Cd than organic matter （OM）, and inversely, higher affinity of Cu to OM than Fe/Mn oxides in NSCSs and SSs was obtained. Meanwhile, it was found that the distributions of heavy metals in NSCSs and SSs were similar to each other and the pseudo-total concentrations of Zn, Cu, Pb and Cd in NSCSs were greater than those in SSs, highlighting the more importance for NSCSs than SSs in controlling behaviours of heavy metals in aquatic environments.展开更多
In order to investigate the adsorption mechanism of trace metals to surficial sediments （SSs）, a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to...In order to investigate the adsorption mechanism of trace metals to surficial sediments （SSs）, a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials （OMs） in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH .HCl （0.1 mol/L） ＋ HNO3 （0.1 mol/L）, （NH4）2C2O4 （0.2 mol/L） ＋ H2C2O4 （pH 3.0）, and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09%--3.36% for the hydroxylamine hydrochloride treatment, 80.63%- 101.09% for the oxalate solution extraction, and 94.76%-102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation ofFe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.展开更多
The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permangan...The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permanganate as a surface treatment. The surface-modified manganese sand was found to be most efficient at removing iron and manganese from water. The metal concentrations in filtered effluent were between 0.01 and 0.04 mg/L, which is far lower than the standard for recycle water. A concen-tration of 5% KMnO4 was found to be most effective as surface modifier. The surface of the manganese sand modified by 5% KMnO4 was examined and found to be covered with a dense membrane of some compound. The membrane had the advantages of uniform texture, large surface area and physical and chemical stability. It was effective at removing iron and manganese from mine water.展开更多
Plant litter will influence the bioavailability of heavy metals in sediments of wetlands used to treat acid mine drainage. To investigate the effect of plant litter on sediments in wetlands and define the comprehensiv...Plant litter will influence the bioavailability of heavy metals in sediments of wetlands used to treat acid mine drainage. To investigate the effect of plant litter on sediments in wetlands and define the comprehensive and continuous role of plant litter, different mass ratios(0%,5%, 20%) of litter were added into the sediments to study the influence of litter decomposition on the overlying water and sediments. The changes in pH, EC, Eh, Fe, and Mn of the overlying water and the organic matter in the sediments and the forms of Fe and Mn after 1, 7, 14, 21, and 28 days of litter decomposition were studied. The results indicated that litter decomposition increased the pH, EC, and reduced Eh of the overlying water. Litter decomposition promoted the release of Fe and Mn from the sediments into the overlying water and with the continuous decomposition of litter, the concentration of Fe and Mn in the overlying water declined. Litter decomposition increased the content of the organic matter in the sediment, and the forms of Fe and Mn indicated that litter decomposition could significantly affect the transformation of the forms of Fe and Mn.Reducible Fe was the main form in the sediments. Litter decomposition promoted the transformation of reducible Fe, the main form found in the sediments, intoexchangeable and oxidizable Fe, but had no effect on residual form. Exchangeable Mn was the main form in the sediments, and litter decomposition accelerated the transformation of reducible Mn, most commonly found in the sediments, into oxidizable Mn and had little influence on the exchangeable and residual forms.展开更多
Manganese abnormity has been observed in the Holocene sediments of the mud area of Bohai Sea. On the basis of grain size, chemical composition, heavy mineral content and accelerator mass spectrometry （AMS） 14C datin...Manganese abnormity has been observed in the Holocene sediments of the mud area of Bohai Sea. On the basis of grain size, chemical composition, heavy mineral content and accelerator mass spectrometry （AMS） 14C dating of foraminifer, relationships between manganese abnormity and sedimentation rates, material source, hydrodynamic conditions are probed. Manganese abnormity occurred during the Middle Holocene when sea level and sedimentation rates were higher than those at present. Sedimentary hiatus was not observed when material sources and hydrodynamic conditions were quite similar. Compared with the former period, the latter period showed a decrease in reduction environment and an inclination toward oxidation environment with high manganese content, whereas provenance and hydrodynamic conditions showed only a slight change. From the above observations, it can be concluded that correlation among manganese abnormity, material source, and hydrodynamic conditions is not obvious. Redox environment seems to be the key factor for manganese enrichment, which is mainly related to marine authigenic process.展开更多
The mixture of(2NaBH4+ MnCl2) was ball milled in a magneto-mill. No gas release was detected. The XRD patterns of the ball milled mixture exhibit only the Bragg diffraction peaks of the Na Cl-type salt which on the ba...The mixture of(2NaBH4+ MnCl2) was ball milled in a magneto-mill. No gas release was detected. The XRD patterns of the ball milled mixture exhibit only the Bragg diffraction peaks of the Na Cl-type salt which on the basis of the present X-ray diffraction results and the literature is likely to be a solid solution Na(Cl)x(BH4)(1-x), possessing a cubic Na Cl-type crystalline structure. No presence of any crystalline hydride was detected by powder X-ray diffraction which clearly shows that NaBH4in the initial mixture must have reacted with MnCl2forming a Na Cl-type by-product and another hydride that does not exhibit X-ray Bragg diffraction peaks. Mass spectrometry(MS) of gas released from the ball milled mixture during combined MS/thermogravimetric analysis(TGA)/differential scanning calorimetry(DSC) experiments, confirms mainly hydrogen(H2) with a small quantity of diborane gas, B2H6. The Fourier transform infra-red(FT-IR) spectrum of the ball milled(2NaBH4+ MnCl2) is quite similar to the FT-IR spectrum of crystalline manganese borohydride, c-Mn(BH4)2, synthesized by ball milling, which strongly suggests that the amorphous hydride mechano-chemically synthesized during ball milling could be an amorphous manganese borohydride. Remarkably, the process of solvent filtration and extraction at 42 °C, resulted in the transformation of mechano-chemically synthesized amorphous manganese borohydride to a nanostructured,crystalline, c-Mn(BH4)2hydride.展开更多
Iron and Manganese contents and parameters including pH, conductivity, and organic matter contents were determined in the sediments of the Okpara dam in Northern Benin. Fifteen samples were collected during a one-mont...Iron and Manganese contents and parameters including pH, conductivity, and organic matter contents were determined in the sediments of the Okpara dam in Northern Benin. Fifteen samples were collected during a one-month period and analysed in laboratory using the method of sequential extraction of Tessier. The analyses indicated that sediments contained high concentrations in reducible fraction of Iron and relatively high contents of exchangeable fraction, acidhydrolysable fraction and residual fraction of Manganese. The findings of this study confirmed the hypotheses that the meal contents of the sediments were relatively high and varied according to the geochemical phases.展开更多
There is an urgent need for low-cost,high-energy-density,environmentally friendly energy storage devices to fulfill the rapidly increasing need for electrical energy storage.Multi-electron redox is considerably crucia...There is an urgent need for low-cost,high-energy-density,environmentally friendly energy storage devices to fulfill the rapidly increasing need for electrical energy storage.Multi-electron redox is considerably crucial for the development of high-energy-density cathodes.Here we present highperformance aqueous zinc-manganese batteries with reversible Mn2+/Mn4+ double redox.The active Mn4+is generated in situ from the Mn2+-containing MnOx nanoparticles and electrolyte.Benefitting from the low crystallinity of the birnessite-type MnO2 as well as the electrolyte with Mn2+additive,the MnOX cathode achieves an ultrahigh energy density with a peak of845.1 Wh kg-1 and an ultralong lifespan of 1500 cycles.The combination of electrochemical measurements and material characterization reveals the reversible Mn2+/Mn4+double redox(birnessite-type MnO2? monoclinic MnOOH and spinel ZnMn2O4 H?Mn2+ions).The reversible Mn2+/Mn4+double redox electrode reaction mechanism offers new opportunities for the design of low-cost,high-energy-density cathodes for advanced rechargeable aqueous batteries.展开更多
In the seawater and sediments of the ocean, there exist huge quantities of bacteria whose living activities cause various chemical reaction processes. It is demonstrated that microorganisms play a fundamental role on ...In the seawater and sediments of the ocean, there exist huge quantities of bacteria whose living activities cause various chemical reaction processes. It is demonstrated that microorganisms play a fundamental role on chemical changes of the sediments and diageneses. Over the last twenty years, great interest has been increased about the role of deep-sea bacteria in the ferromanganese sedimentary process. Much work has been done on this aspect in the Atlantic Ocean, the Baltic Sea and the Pacific O-展开更多
Mn-Zn ferrite powders were produced from low-grade manganese ore(LMO) via the chemical coprecipitation method combined with the ceramic method,after the LMO was leached in sulfuric acid and the obtained solution was p...Mn-Zn ferrite powders were produced from low-grade manganese ore(LMO) via the chemical coprecipitation method combined with the ceramic method,after the LMO was leached in sulfuric acid and the obtained solution was purified.The effect of the pH on the magnetic properties of Mn-Zn ferrite was investigated by the varying pH of the co-precipitation system.The crystal structure and phases of the samples were characterized by X-ray diffraction and infrared spectrum,respectively.The magnetic measurements were carried out on a vibrating sample magnetometer.The optimal sample was obtained with a saturation magnetization of 55.02 emu/g,a coercivity of 8.20 G and a remanent magnetization of1.71 emu/g when pH is 7.5.展开更多
基金The National Basic Research Program (973) of China (No. 2004CB3418500)
文摘Natural surface coating samples （NSCSs） from the surface of shingles and surficial sediments （SSs） in the Songhua River, China were employed to investigate the relationship between NSCSs and SSs in fractions of heavy metals （Fe, Mn, Zn, Cu, Pb, and Cd） using the modified sequential extraction procedure （MSEP）. The results show that the differences between NSCSs and SSs in Fe fi＇actions were insignificant and Fe was dominantly present as residual phase （76.22% for NSCSs and 80.88% for SSs） and Fe-oxides phase （20.33% for NSCSs and 16.15% for SSs）. Significant variation of Mn distribution patterns between NSCSs and SSs was observed with Mn in NSCSs mainly present in Mn-oxides phase （48.27%） and that in SSs present as residual phase （45.44%）. Zn, Cu, Pb and Cd were found dominantly in residual fractions （〉48%）, and next in solid oxides/hydroxides for Zn, Pb and Cd and in easily oxidizable solids/compounds form for Cu, respectively. The heavy metal distribution patterns implied that Fe/Mn oxides both in NSCSs and SSs were more important sinks for binding and adsorption of Zn, Pb and Cd than organic matter （OM）, and inversely, higher affinity of Cu to OM than Fe/Mn oxides in NSCSs and SSs was obtained. Meanwhile, it was found that the distributions of heavy metals in NSCSs and SSs were similar to each other and the pseudo-total concentrations of Zn, Cu, Pb and Cd in NSCSs were greater than those in SSs, highlighting the more importance for NSCSs than SSs in controlling behaviours of heavy metals in aquatic environments.
基金The National Basic Research Program (973) of China (No. 2004CB3418501)
文摘In order to investigate the adsorption mechanism of trace metals to surficial sediments （SSs）, a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials （OMs） in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH .HCl （0.1 mol/L） ＋ HNO3 （0.1 mol/L）, （NH4）2C2O4 （0.2 mol/L） ＋ H2C2O4 （pH 3.0）, and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09%--3.36% for the hydroxylamine hydrochloride treatment, 80.63%- 101.09% for the oxalate solution extraction, and 94.76%-102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation ofFe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.
基金provided by the National Hi-tech Research and Development Program of China (No.2008AA06z305)the National Natural Science Foundation of China (No.50678172)the Science and Technology Research Program of the Ministry of Education of China (No.107022)
文摘The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permanganate as a surface treatment. The surface-modified manganese sand was found to be most efficient at removing iron and manganese from water. The metal concentrations in filtered effluent were between 0.01 and 0.04 mg/L, which is far lower than the standard for recycle water. A concen-tration of 5% KMnO4 was found to be most effective as surface modifier. The surface of the manganese sand modified by 5% KMnO4 was examined and found to be covered with a dense membrane of some compound. The membrane had the advantages of uniform texture, large surface area and physical and chemical stability. It was effective at removing iron and manganese from mine water.
基金provided by the United Fund of Guizhou Province Government and National Natural Science Foundation of China (No. U1612442)the Natural and Science Project by the Education Department of Guizhou Province (Nos. KY2016011, GZZ201607, and ZDXK201611)
文摘Plant litter will influence the bioavailability of heavy metals in sediments of wetlands used to treat acid mine drainage. To investigate the effect of plant litter on sediments in wetlands and define the comprehensive and continuous role of plant litter, different mass ratios(0%,5%, 20%) of litter were added into the sediments to study the influence of litter decomposition on the overlying water and sediments. The changes in pH, EC, Eh, Fe, and Mn of the overlying water and the organic matter in the sediments and the forms of Fe and Mn after 1, 7, 14, 21, and 28 days of litter decomposition were studied. The results indicated that litter decomposition increased the pH, EC, and reduced Eh of the overlying water. Litter decomposition promoted the release of Fe and Mn from the sediments into the overlying water and with the continuous decomposition of litter, the concentration of Fe and Mn in the overlying water declined. Litter decomposition increased the content of the organic matter in the sediment, and the forms of Fe and Mn indicated that litter decomposition could significantly affect the transformation of the forms of Fe and Mn.Reducible Fe was the main form in the sediments. Litter decomposition promoted the transformation of reducible Fe, the main form found in the sediments, intoexchangeable and oxidizable Fe, but had no effect on residual form. Exchangeable Mn was the main form in the sediments, and litter decomposition accelerated the transformation of reducible Mn, most commonly found in the sediments, into oxidizable Mn and had little influence on the exchangeable and residual forms.
基金This paper is supported by the National Natural Science Foundation of China (No. 40576032).
文摘Manganese abnormity has been observed in the Holocene sediments of the mud area of Bohai Sea. On the basis of grain size, chemical composition, heavy mineral content and accelerator mass spectrometry （AMS） 14C dating of foraminifer, relationships between manganese abnormity and sedimentation rates, material source, hydrodynamic conditions are probed. Manganese abnormity occurred during the Middle Holocene when sea level and sedimentation rates were higher than those at present. Sedimentary hiatus was not observed when material sources and hydrodynamic conditions were quite similar. Compared with the former period, the latter period showed a decrease in reduction environment and an inclination toward oxidation environment with high manganese content, whereas provenance and hydrodynamic conditions showed only a slight change. From the above observations, it can be concluded that correlation among manganese abnormity, material source, and hydrodynamic conditions is not obvious. Redox environment seems to be the key factor for manganese enrichment, which is mainly related to marine authigenic process.
基金supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery grant to Prof. R.A. Varin
文摘The mixture of(2NaBH4+ MnCl2) was ball milled in a magneto-mill. No gas release was detected. The XRD patterns of the ball milled mixture exhibit only the Bragg diffraction peaks of the Na Cl-type salt which on the basis of the present X-ray diffraction results and the literature is likely to be a solid solution Na(Cl)x(BH4)(1-x), possessing a cubic Na Cl-type crystalline structure. No presence of any crystalline hydride was detected by powder X-ray diffraction which clearly shows that NaBH4in the initial mixture must have reacted with MnCl2forming a Na Cl-type by-product and another hydride that does not exhibit X-ray Bragg diffraction peaks. Mass spectrometry(MS) of gas released from the ball milled mixture during combined MS/thermogravimetric analysis(TGA)/differential scanning calorimetry(DSC) experiments, confirms mainly hydrogen(H2) with a small quantity of diborane gas, B2H6. The Fourier transform infra-red(FT-IR) spectrum of the ball milled(2NaBH4+ MnCl2) is quite similar to the FT-IR spectrum of crystalline manganese borohydride, c-Mn(BH4)2, synthesized by ball milling, which strongly suggests that the amorphous hydride mechano-chemically synthesized during ball milling could be an amorphous manganese borohydride. Remarkably, the process of solvent filtration and extraction at 42 °C, resulted in the transformation of mechano-chemically synthesized amorphous manganese borohydride to a nanostructured,crystalline, c-Mn(BH4)2hydride.
文摘Iron and Manganese contents and parameters including pH, conductivity, and organic matter contents were determined in the sediments of the Okpara dam in Northern Benin. Fifteen samples were collected during a one-month period and analysed in laboratory using the method of sequential extraction of Tessier. The analyses indicated that sediments contained high concentrations in reducible fraction of Iron and relatively high contents of exchangeable fraction, acidhydrolysable fraction and residual fraction of Manganese. The findings of this study confirmed the hypotheses that the meal contents of the sediments were relatively high and varied according to the geochemical phases.
基金supported by the National Natural Science Foundation of China(Grant No.51772331)the National Key Technologies R&D Program(Grant No.2018YFB1106000).
文摘There is an urgent need for low-cost,high-energy-density,environmentally friendly energy storage devices to fulfill the rapidly increasing need for electrical energy storage.Multi-electron redox is considerably crucial for the development of high-energy-density cathodes.Here we present highperformance aqueous zinc-manganese batteries with reversible Mn2+/Mn4+ double redox.The active Mn4+is generated in situ from the Mn2+-containing MnOx nanoparticles and electrolyte.Benefitting from the low crystallinity of the birnessite-type MnO2 as well as the electrolyte with Mn2+additive,the MnOX cathode achieves an ultrahigh energy density with a peak of845.1 Wh kg-1 and an ultralong lifespan of 1500 cycles.The combination of electrochemical measurements and material characterization reveals the reversible Mn2+/Mn4+double redox(birnessite-type MnO2? monoclinic MnOOH and spinel ZnMn2O4 H?Mn2+ions).The reversible Mn2+/Mn4+double redox electrode reaction mechanism offers new opportunities for the design of low-cost,high-energy-density cathodes for advanced rechargeable aqueous batteries.
文摘In the seawater and sediments of the ocean, there exist huge quantities of bacteria whose living activities cause various chemical reaction processes. It is demonstrated that microorganisms play a fundamental role on chemical changes of the sediments and diageneses. Over the last twenty years, great interest has been increased about the role of deep-sea bacteria in the ferromanganese sedimentary process. Much work has been done on this aspect in the Atlantic Ocean, the Baltic Sea and the Pacific O-
基金financed by the Bureau of Land Resources and Housing Management of Chongqing(Scientific & Technologic Program in 2011)the Science and Technology Bureau of Hengyang(Scientific & Technologic Program in 2013)the State Administration of Work Safety(Scientific & Technologic Program in 2013)
文摘Mn-Zn ferrite powders were produced from low-grade manganese ore(LMO) via the chemical coprecipitation method combined with the ceramic method,after the LMO was leached in sulfuric acid and the obtained solution was purified.The effect of the pH on the magnetic properties of Mn-Zn ferrite was investigated by the varying pH of the co-precipitation system.The crystal structure and phases of the samples were characterized by X-ray diffraction and infrared spectrum,respectively.The magnetic measurements were carried out on a vibrating sample magnetometer.The optimal sample was obtained with a saturation magnetization of 55.02 emu/g,a coercivity of 8.20 G and a remanent magnetization of1.71 emu/g when pH is 7.5.
