The characteristics of electric charge and molecular weight distribution,oxidation-reduction regimes,e.g.Eh and amounts of organic reducing substances produced by milk vetch during anaerobic decomposition process,were...The characteristics of electric charge and molecular weight distribution,oxidation-reduction regimes,e.g.Eh and amounts of organic reducing substances produced by milk vetch during anaerobic decomposition process,were studied by using electrochemical methods.Interaction between soils and organic reducing substances was also observed.The results indicate that the organic reducing substances were mainly the organic compounds with negative and amphoteric charges,which were distributed in two groups at anodic peak potentials of 0.25 and 0.69 volt in differential pulse voltammograms,respectively.Their apparent molecular weights are all less than 700 daltons,in which those active in oxidation-reducion reaction were distributed in the fraction with apparent molecular weight less than 200 daltons.The organic reduction substances can be oxidized by manganese oxides in their interaction with soils.展开更多
A new method was proposed for study of organic reducing substances in soils. According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances, the wo...A new method was proposed for study of organic reducing substances in soils. According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances, the working conditions of differential pulse voltammetry (d.p. v.) for determining the organic reducing substances produced during the processes of the anaerobic decomposition of plant materials were established with a glass carbon electrode as working electrode, 1 M Ag-AgCl electrode with large area as reference electrode, 0.2 M NH4AC as supporting electrolyte and pH buffer solution, pulse amplitude (AE) of 25 mV, scan rate at 2 mV·S-1and scan potential ranging from -0.5 to +1.2 voltage(vs. M Ag-AgCl). The peak current proportional to the concentration of reducing substances, and the characteristic peak potential of each organic reducing substance were regarded as the quantitative and qualitative base, respectively. These results obtained under the conditions mentioned above directly reflect both the reducing intensity and capacity of the organic reducing system in soils.展开更多
Some electrochemical properties,such as PH,Eh,and voltammetric behavior,of the decomposition products of rice straw and the in eractions of these products with soils were studied.The PH,Eh,and amounts of organic reduc...Some electrochemical properties,such as PH,Eh,and voltammetric behavior,of the decomposition products of rice straw and the in eractions of these products with soils were studied.The PH,Eh,and amounts of organic reducing substances changed markedly during the 60-day anaerobic decomposition.pH decreased sharply to pH 5 on the tenth day and then increased gradually to 7 on the 45th day.The amouats of organic reducing substances increased almost synchronously with the fall of redox potential during the first 15 days.The differential pulse voltammetric(dpv) behavior changed not only in the peak current but also in the peak potential.The fractions with apparent molecular weights lower than 200 dations appeared to be active in dpv behavior.The electric charge of organic reducing substances was closely related to the decomposition stage.The 6th day of incubation was the crucial time before and after which the major part of the components was negatively charged and positively charged, respectively.The group with a low apparent molecular weight and a negative charge was the main components responsible for the lower anodic peak potentials.They were oxidized first during the interactions of the organic reducing substances with soils.展开更多
A method was established for qualitative and quantitative determination of the reducing substances from plastic blood bags aqueous extract.The samples were extracted with a solid-phase extraction procedure,dichloromet...A method was established for qualitative and quantitative determination of the reducing substances from plastic blood bags aqueous extract.The samples were extracted with a solid-phase extraction procedure,dichloromethane qua extract solvents,and were measured with GC-MS.With this method,we determined several reducing substances from plastic blood bags aqueous extract and fixed quantify on DEHP (di (2-ethylhexyl) phthalate),one of the dominating reducing substances.The method was simple and can be used for the quality control of plastic blood bags.展开更多
The gleyisation of representative paddy soils in the middle reaches of the Yangtze caver was characterized,taking oxidation-reduction potential(Eh),the amount of active reducing substances and the forms of iron and ma...The gleyisation of representative paddy soils in the middle reaches of the Yangtze caver was characterized,taking oxidation-reduction potential(Eh),the amount of active reducing substances and the forms of iron and manganese as the parameters.The Eh value was linearly related with the logarithm of the amount of active reducing substances, which was contributed by ferrous iron by 83% on an avers.The degree of gleyization of dament horizons was graded as ungleyed,slightly gleyed,mildly gleyed and gleyed.The Eh of the four grades was>500,300-500,100-300 and<100 mV,respectively, and the corresponding amoks of active reducing substances was<1,1-7,7-30 and>30 mmol.kg(-1),respectively.The amount of ferrous iron of the four grades was<0.5,0.5-5,5-25 and > 25 mmol kg-1,respectively.The extent of gleyisation of a soil was classified as upper-gleyed, middle-gleyed and lower-gleyed, depending on whether the depth of the gley horbon was less than 30 cm,30-60 cm or more than 60 cm.展开更多
This paper studied the biofilm properties and corrosion behavior of sulfate reducing bacteria （SRB） on stainless steel 316L （SS316L） surface in circulating cooling water system with and without additives including...This paper studied the biofilm properties and corrosion behavior of sulfate reducing bacteria （SRB） on stainless steel 316L （SS316L） surface in circulating cooling water system with and without additives including hydroxy ethyl fork phosphonic acid （HEDP）, dodecyl dimethyl benzyl anunonium chlotide （1227） and NaClO. Biochemical technique, electrochemical technology, X-ray photoelectron spectroscopy （XPS） and scanning electron microscope （SEM） were used. The results show that the extracellular polymeric substance （EPS） in biofilm attached on the SS316L surface mainly contain proteins and polysaccharides, the contents are 98 ug.cm-2 and 635ug.cm-2, respectively. The polysaccharides were cut by 1227 about 80%, while 55% by NaCIO. The proteins were reduced by NaCIO about 53%, while only 30% by 1227. The potentiodynamic polarization shows that the corrosion potential of SS316L was enhanced from -0.495 V to -0.390 V by the chemical additive delaying the occurrence of the corrosion. And the corrosion rate was also reduced from 5.19 × 10^-3 mm·a^-1 to 2.42 × 10^-3 mm＇a . But NaCIO stdl caused pitting corrosion after stenhzmg the bacteria, while 1227 can form a protective film on the surface of SS316L. Though HEDP contribute to the bacteria activity, it can enhance the breakdown potential. XPS results confirmed that 1227 can change the value of C：O in the biofilm attached on metal surface, and NaCIO can eliminate the existence of amidogen. This study would provide some recommendations for the selection of chemical additives in the thermal power plant.展开更多
文摘The characteristics of electric charge and molecular weight distribution,oxidation-reduction regimes,e.g.Eh and amounts of organic reducing substances produced by milk vetch during anaerobic decomposition process,were studied by using electrochemical methods.Interaction between soils and organic reducing substances was also observed.The results indicate that the organic reducing substances were mainly the organic compounds with negative and amphoteric charges,which were distributed in two groups at anodic peak potentials of 0.25 and 0.69 volt in differential pulse voltammograms,respectively.Their apparent molecular weights are all less than 700 daltons,in which those active in oxidation-reducion reaction were distributed in the fraction with apparent molecular weight less than 200 daltons.The organic reduction substances can be oxidized by manganese oxides in their interaction with soils.
文摘A new method was proposed for study of organic reducing substances in soils. According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances, the working conditions of differential pulse voltammetry (d.p. v.) for determining the organic reducing substances produced during the processes of the anaerobic decomposition of plant materials were established with a glass carbon electrode as working electrode, 1 M Ag-AgCl electrode with large area as reference electrode, 0.2 M NH4AC as supporting electrolyte and pH buffer solution, pulse amplitude (AE) of 25 mV, scan rate at 2 mV·S-1and scan potential ranging from -0.5 to +1.2 voltage(vs. M Ag-AgCl). The peak current proportional to the concentration of reducing substances, and the characteristic peak potential of each organic reducing substance were regarded as the quantitative and qualitative base, respectively. These results obtained under the conditions mentioned above directly reflect both the reducing intensity and capacity of the organic reducing system in soils.
文摘Some electrochemical properties,such as PH,Eh,and voltammetric behavior,of the decomposition products of rice straw and the in eractions of these products with soils were studied.The PH,Eh,and amounts of organic reducing substances changed markedly during the 60-day anaerobic decomposition.pH decreased sharply to pH 5 on the tenth day and then increased gradually to 7 on the 45th day.The amouats of organic reducing substances increased almost synchronously with the fall of redox potential during the first 15 days.The differential pulse voltammetric(dpv) behavior changed not only in the peak current but also in the peak potential.The fractions with apparent molecular weights lower than 200 dations appeared to be active in dpv behavior.The electric charge of organic reducing substances was closely related to the decomposition stage.The 6th day of incubation was the crucial time before and after which the major part of the components was negatively charged and positively charged, respectively.The group with a low apparent molecular weight and a negative charge was the main components responsible for the lower anodic peak potentials.They were oxidized first during the interactions of the organic reducing substances with soils.
文摘A method was established for qualitative and quantitative determination of the reducing substances from plastic blood bags aqueous extract.The samples were extracted with a solid-phase extraction procedure,dichloromethane qua extract solvents,and were measured with GC-MS.With this method,we determined several reducing substances from plastic blood bags aqueous extract and fixed quantify on DEHP (di (2-ethylhexyl) phthalate),one of the dominating reducing substances.The method was simple and can be used for the quality control of plastic blood bags.
文摘The gleyisation of representative paddy soils in the middle reaches of the Yangtze caver was characterized,taking oxidation-reduction potential(Eh),the amount of active reducing substances and the forms of iron and manganese as the parameters.The Eh value was linearly related with the logarithm of the amount of active reducing substances, which was contributed by ferrous iron by 83% on an avers.The degree of gleyization of dament horizons was graded as ungleyed,slightly gleyed,mildly gleyed and gleyed.The Eh of the four grades was>500,300-500,100-300 and<100 mV,respectively, and the corresponding amoks of active reducing substances was<1,1-7,7-30 and>30 mmol.kg(-1),respectively.The amount of ferrous iron of the four grades was<0.5,0.5-5,5-25 and > 25 mmol kg-1,respectively.The extent of gleyisation of a soil was classified as upper-gleyed, middle-gleyed and lower-gleyed, depending on whether the depth of the gley horbon was less than 30 cm,30-60 cm or more than 60 cm.
基金Acknowledgements The authors would like to acknowledge the financial support in a grant from the National Natural Science Foundation of China （Grant No. 51278035）.
文摘This paper studied the biofilm properties and corrosion behavior of sulfate reducing bacteria （SRB） on stainless steel 316L （SS316L） surface in circulating cooling water system with and without additives including hydroxy ethyl fork phosphonic acid （HEDP）, dodecyl dimethyl benzyl anunonium chlotide （1227） and NaClO. Biochemical technique, electrochemical technology, X-ray photoelectron spectroscopy （XPS） and scanning electron microscope （SEM） were used. The results show that the extracellular polymeric substance （EPS） in biofilm attached on the SS316L surface mainly contain proteins and polysaccharides, the contents are 98 ug.cm-2 and 635ug.cm-2, respectively. The polysaccharides were cut by 1227 about 80%, while 55% by NaCIO. The proteins were reduced by NaCIO about 53%, while only 30% by 1227. The potentiodynamic polarization shows that the corrosion potential of SS316L was enhanced from -0.495 V to -0.390 V by the chemical additive delaying the occurrence of the corrosion. And the corrosion rate was also reduced from 5.19 × 10^-3 mm·a^-1 to 2.42 × 10^-3 mm＇a . But NaCIO stdl caused pitting corrosion after stenhzmg the bacteria, while 1227 can form a protective film on the surface of SS316L. Though HEDP contribute to the bacteria activity, it can enhance the breakdown potential. XPS results confirmed that 1227 can change the value of C：O in the biofilm attached on metal surface, and NaCIO can eliminate the existence of amidogen. This study would provide some recommendations for the selection of chemical additives in the thermal power plant.
