Synergically regulated silver species and surface oxygen on manganese oxide for promoted activity of formaldehyde oxidation

Formaldehyde (HCHO) is a common indoor pollutant that is detrimental to human health.Its efficient removal has become an urgent demand to reduce the public health risk.In this work,Ag-MnO_x-based catalysts were prepared and activated under different atmosphere(i.e.,air,hydrogen (H₂) and carbon monoxide (CO)) for efficient oxidation of HCHO.The catalyst activated with CO (Ag/Mn-CO) displayed the highest activity among the tested samples with 90%conversion at 100°C under a gas...     

Carbon dioxide adsorption and cycloaddition reaction of epoxides using chitosan–graphene oxide nanocomposite as a catalyst

One of today's major challenges is to provide green materials for a cleaner environment. We have conducted studies on carbon dioxide(CO2) adsorption and conversion to valuable products by an ecofriendly approach based in chitosan/graphene oxide(CSGO) nanocomposite film. Rheological behavior indicates that the CSGO has a better solvation property than the pure chitosan. An adsorption capacity of 1.0152 mmol CO_2/g of CSGO nanocomposite at4.6 bar was observed. The catalytic behavior of the CSGO nanocomposite in the presence of tetra-n-butylammonium iodide(n-Bu4 NI) as co-catalyst was evaluated for the cycloaddition of CO_2 to epoxides, to give cyclic carbonates, in the absence of any solvent. These results strongly suggest that the CSGO nanocomposite may open new vistas towards the development of ecofriendly material for catalytic conversion and adsorption of CO_2 on industrial scale.     

Release kinetics of vanadium from vanadium(Ⅲ, Ⅳ and Ⅴ) oxides: Effect of pH,temperature and oxide dose

Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium(Ⅲ, Ⅳ and Ⅴ) oxides at pH 3.1–10.0. The release rates of vanadium are closely related to the aqueous pH, and several obvious differences were observed in the release behavior of vanadium from the dissolution of V_2O_5 and vanadium(Ⅲ, Ⅳ) oxides. In the first 2 hr, the release rates of vanadium from V_2O_3 were r = 1.14·([H~+])~0.269 at pH 3.0–6.0 and r = 0.016·([H~+])~(-0.048) at pH 6.0–10.0; the release rates from VO_2 were r = 0.362·([H~+])~0.129 at pH 3.0–6.0 and r = 0.017·([H~+])~(-0.097) at pH 6.0–10.0; and the release rates from V_2O_5 were r = 0.131·([H~+])-~(0.104) at pH 3.1–10.0. The release rates of vanadium from the three oxides increased with increasing temperature, and the effect of temperature was different at pH 3.8, pH 6.0 and pH 7.7. The activation energies of vanadium(Ⅲ, Ⅳ and Ⅴ) oxides(33.4–87.5 kJ/mol) were determined at pH 3.8, pH 6.0 and pH 7.7, showing that the release of vanadium from dissolution of vanadium oxides follows a surface-controlled reaction mechanism. The release rates of vanadium increased with increasing vanadium oxides dose,albeit not proportionally. This study, as part of a broader study of the release behavior of vanadium, can help to elucidate the pollution problem of vanadium and to clarify the fate of vanadium in the environment.     

Measurement of nitrous oxide emission dynamics from soil

A simple laboratory device which simulates environmental factors that affect N₂O emission from soil has been constructed． It is convenient to use it to observe the N₂O emission dynamics from soil cores while simulating some factors such as different fertilizer sources，management，temperature．and chemical inhibitors，etc．The detect limit was 2．5mg N₂O-N m^{-2．s-1 with maxinlum error about 10%, so it could be used for agricultural soils It was found that fertilizer source，fertilizer management and native soil type were preliminarily important factors on N₂O emission fluxes in some of our experiments．}     

Underestimation of phosphorus fraction change in the supernatant after phosphorus adsorption onto iron oxides and iron oxide–natural organic matter complexes

The phosphorus(P) fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid(HA) complexes were analyzed using the ultrafiltration method in this study.With an initial P concentration of 20 mg/L(I =0.01 mol/L and pH = 7),it was shown that the colloid(1 kDa-0.45 μm) component of P accounted for 10.6%,11.6%,6.5%,and 4.0%of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite(FH),goethite(GE),ferrihydrite-humic acid complex(FH-HA),goethite-humic acid complex(GE-HA),respectively.The 1 kDa component of P was still the predominant fraction in the supernatant,and underestimated colloidal P accounted for 2.2%,55.1%,45.5%,and 38.7%of P adsorption onto the solid surface of FH,FH-HA,GE and GE-HA,respectively.Thus,the colloid P could not be neglected.Notably,it could be interpreted that Fe~(3+) hydrolysis from the adsorbents followed by the formation of colloidal hydrous ferric oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant.And colloidal adsorbent particles co-existing in the supernatant were another important reason for it.Additionally,dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant.Ultimately,we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P,even when considering other contaminants such as organic pollutants,heavy metal ions,and arsenate at the sediment/soil-water interface in the real environment.     

Simultaneous removal of Congo red and cadmium(II) from aqueous solutions using graphene oxide–silica composite as a multifunctional adsorbent

Graphene oxide is a very high capacity adsorbent due to its functional groups and π?π interactions with other compounds. Adsorption capacity of graphene oxide, however, can be further enhanced by having synergistic effects through the use of mixed-matrix composite. In this study, silica-decorated graphene oxide (SGO) was used as a high-efficiency adsorbent to remove Congo red (CR) and Cadmium (II) from aqueous solutions. The effects of solution initial concentration (20 to 120 mg/l), solution pH (pH 2 to 7), adsorption duration (0 to 140 min) and temperature (298 to 323 K) were measured in order to optimize the adsorption conditions using the SGO adsorbent. Morphological analysis indicated that the silica nanoparticles could be dispersed uniformly on the graphene oxide surfaces. The maximum capacities of adsorbent for effective removal of Cd (II) and CR were 43.45 and 333.33 mg/g based on Freundlich and Langmuir isotherms, respectively. Langmuir and Freundlich isotherms displayed the highest values of Q_max for CR and Cd (II) adsorption in this study, which indicated monolayer adsorption of CR and multilayer adsorption of Cd (II) onto the SGO, respectively. Thermodynamic study showed that the enthalpy (ΔH) and Gibbs free energy(ΔG) values of the adsorption process for both pollutants were negative, suggesting that the process was spontaneous and exothermic in nature. This study showed active sites of SGO (π-π, hydroxyl, carboxyl, ketone, silane-based functional groups) contributed to an enormous enhancement in simultaneous removal of CR and Cd (II) from an aqueous solution, Therefore, SGO can be considered as a promising adsorbent for future water pollution control and removal of hazardous materials from aqueous solutions.     

On the determination of nitrous oxide emission factor during biomass burning

ＯｎｔｈｅｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｎｉｔｒｏｕｓｏｘｉｄｅｅｍｉｓｓｉｏｎｆａｃｔｏｒｄｕｒｉｎｇｂｉｏｍａｓｓｂｕｒｎｉｎｇＣａｏＭｅｉｑｉｕ；ＺｈｕａｎｇＹａｈｕｉ（ＲｅｓｅａｒｃｈＣｅｎｔｅｒｆｏｒＥｃｏ－ＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉ...     

Investigation of protein-styrene oxide adducts as a molecularbiomarker of human exposed to styrene

ＩｎｔｒｏｄｕｃｔｉｏｎＢｉｏｍａｒｋｅｒ ,ｄｅｆｉｎｅｄａｓｃｅｌｌｕｌａｒ,ｂｉｏｃｈｅｍｉｃａｌｏｒｍｏｌｅｃｕｌａｒａｌｔｅｒａｔｉｏｎｓｔｈａｔａｒｅｍｅａｓｕｒａｂｌｅｉｎｂｉｏｌｏｇｉｃａｌｍｅｄｉａ ,ｓｕｃｈａｓｈｕｍａｎｔｉｓｓｕｅｓ ,ｃｅｌｌｓ,ｏｒｆｌｕｉｄｓ ,ｈａｖｅｂｅｅｎｕｓｅｄｂｙｇｅｎｅｒａｔｉｏｎｓｏｆｅｐｉｄｅｍｉｏｌｏｇｉｓｔｓｉｎｔｈｅｉｒｒｅｓｅａｒｃｈ .Ｍｏｌｅｃｕｌａｒｂｉｏｌｏｇｙａｎｄｌａｂｏｒａｔｏｒｙｔｅｃｈｎｏｌｏｇｙｈａｖｅｓｈｏｗｎａｎｅ…     

Removal of arsenate with hydrous ferric oxide coprecipitation：Effect of humic acid

Insights from the adverse effect of humic acid(HA) on arsenate removal with hydrous ferric oxide(HFO) coprecipitation can further our understanding of the fate of As(V) in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As(V) on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering(SERS), extended X-ray absorption fine structure(EXAFS) spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared(ATR-FTIR) measurement, and charge distribution multisite complexation(CDMUSIC) modeling. The As(V) removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As(V) mass concentration. The SERS analysis excluded the HA-As(V) complex formation. The EXAFS results indicate that As(V) formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26–3.31 ?. The in situ ATR-FTIR measurements show that As(V) replaces surface hydroxyl groups and forms innersphere complex. High concentrations of HA may physically block the surface sites and inhibit the As(V) access. The adsorption of As(V) and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As(V) and HA reasonably well.     

Decreased emission of nitrous oxide from delivery wards—case study in Sweden

The very potent greenhouse gas nitrous oxide (N₂O) is widely used as a mild anaesthetic for mothers in delivery work in Sweden. As a part of the Stockholm County Council environmental program it was decided in 2002 that the emissions should be drastically reduced. Different ways were theoretically evaluated, and catalytic splitting to nitrogen and oxygen gas (N₂ and O₂) was chosen for a demonstration installation. A Japanese commercial unit for treatment of mixed anaesthetic gases (Anesclean® from Showa Denko K.K.) was thoroughly modified and installed at the Karolinska University Hospital at Huddinge in Stockholm in 2004. The destruction of N₂O was optimised and studied for 2 years. Data from both collection and destruction are given in the article. Of the collected N₂O more than 95% was split to N₂ and O₂ in the very stable system. The overall emission decrease was mainly dependent on the share that could be collected in the specific exhaustion system as compared to the normal room ventilation. Life cycle assessment (LCA) and life cycle costing (LCC) were used to evaluate the actual environmental value and economical cost for the process. Important factors are pointed out.     

A primary study of nitrous oxide emission in agriculture region of Northern China

Significance of nitrous oxide in atmospheric chemistry is reviewed briefly. Background concentration of N2O at Wudaoliang in Qinghai Province of Western China has been measured by collecting gas samples and analysing them with electron capture-gas chromatography. The atmospheric concentration fluctuates in the range of 303-315 ppb with the mean value of 308 ppb. The emission rate of N2O in agriculture region of Northern China has been studied primarily. Fertilization, rain and temperature of soil appear conductible to N2O emission. The interactions between greenhouse effect and N2O emission have been discussed. The catalytic action of N2O in stratospheric ozone depletion processes and the effect of high N2O concentration on ozone depletion in stratosphere have been considered and discussed.     

Cytogenetic studies of chromium(Ⅲ) oxide nanoparticles on Allium cepa root tip cells

The current study evaluates the cytogenetic effects of chromium(Ⅲ) oxide nanoparticles on the root cells of Allium cepa.The root tip cells of A.cepa were treated with the aqueous dispersions of Cr_2O_3 nanoparticles(NPs) at five different concentrations(0.01,0.1,1,10,and 100 μg/m L) for 4 hr.The colloidal stability of the nanoparticle suspensions during the exposure period were ascertained by particle size analyses.After 4 hr exposure to Cr_2O_3 NPs,a significant decrease in mitotic index(MI) from 35.56%(Control) to 35.26%(0.01 μg/m L),34.64%(0.1 μg/m L),32.73%(1 μg/m L),29.6%(10 μg/m L) and 20.92%(100 μg/m L) was noted.The optical,fluorescence and confocal laser scanning microscopic analyses demonstrated specific chromosomal aberrations such as—chromosome stickiness,chromosome breaks,laggard chromosome,clumped chromosome,multipolar phases,nuclear notch,and nuclear bud at different exposure concentrations.The concentration-dependent internalization/bio-uptake of Cr_2O_3 NPs may have contributed to the enhanced production of anti oxidant enzyme,superoxide dismutase to counteract the oxidative stress,which in turn resulted in observed chromosomal aberrations and cytogenetic effects.These results suggest that A.cepa root tip assay can be successfully applied for evaluating environmental risk of Cr_2O_3 NPs over a wide range of concentrations.     

Catalytic degradation of chlorinated volatile organic compounds (CVOCs) over Ce-Mn-Ti composite oxide catalysts

Developing industrially moldable catalysts with harmonized redox performance and acidity is of great significance for the efficient disposal of chlorinated volatile organic compounds(CVOCs) in actual exhaust gasses. Here, commercial TiO₂, typically used for molding catalysts, was chosen as the carrier to fabricate a series of Ce_0.02Mn_0–0.24TiO_x materials with different Mn doping ratios and employed for chlorobenzene(CB) destruction. The introduction of...     

Three industries and wastewater and COD discharge of Beijing

Ｒｅｃｅｎｔｌｙ,ｗｉｔｈｔｈｅｓｗｉｆｔｄｅｖｅｌｏｐｍｅｎｔｏｆｅｃｏｎｏｍｙａｎｄｔｈｅｉｍｐｒｏｖｅｍｅｎｔｏｆｐｅｏｐｌｅ′ｓｌｉｖｉｎｇｓｔａｎｄａｒｄ ,ｔｈｅｗａｔｅｒｕｓｅａｍｏｕｎｔａｎｄｗａｓｔｅｗａｔｅｒｄｉｓｃｈａｒｇｅｂｅｃｏｍｅｂｉｇｇｅｒａｎｄｂｉｇｇｅｒ,ａｎｄｔｈｅｗａｔｅｒｑｕａｌｉｔｙｉｓｇｅｔｔｉｎｇｗｏｒｓｅａｎｄｗｏｒｓｅ .Ｓｏｉｌａｎｄａｇｒｉｃｕｌｔｕｒａｌｐｒｏｄｕｃｔｓｈａｖｅｂｅｅｎｐｏｌｌｕｔｅｄｂｙｔｈｅｗａｓｔｅｗａｔｅｒ,ａｎｄｐｅｏｐ…     

Role of nitric oxide in the genotoxic response to chronic microcystin-LR exposure in human–hamster hybrid cells

Microcystin-LR(MC-LR) is the most abundant and toxic microcystin congener and has been classified as a potential human carcinogen(Group 2B) by the International Agency for Research on Cancer. However, the mechanisms underlying the genotoxic effects of MC-LR during chronic exposure are still poorly understood. In the present study, human–hamster hybrid(AL) cells were exposed to MC-LR for varying lengths of time to investigate the role of nitrogen radicals in MC-LR-induced genotoxicity. The mutagenic potential at the CD59 locus was more than 2-fold higher(p 0.01) in ALcells exposed to a cytotoxic concentration(1 μmol/L) of MC-LR for 30 days than in untreated control cells, which was consistent with the formation of micronucleus. MC-LR caused a dose-dependent increase in nitric oxide(NO) production in treated cells. Moreover, this was blocked by concurrent treatment with the NO synthase inhibitor NG-methyl-L-arginine(L-NMMA), which suppressed MC-LRinduced mutations as well. The survival of mitochondrial DNA-depleted(ρ0) ALcells was markedly decreased by MC-LR treatment compared to that in ALcells, while the CD59 mutant fraction was unaltered. These results provided clear evidence that the genotoxicity associated with chronic MC-LR exposure in mammalian cells was mediated by NO and might be considered as a basis for the development of therapeutics that prevent carcinogenesis.     

Role of nitric oxide in the genotoxic response to chronic microcystin-LR exposure in human–hamster hybrid cells

Microcystin-LR (MC-LR) is the most abundant and toxic microcystin congener and has been classified as a potential human carcinogen (Group 2B) by the International Agency for Research on Cancer. However, the mechanisms underlying the genotoxic effects of MC-LR during chronic exposure are still poorly understood. In the present study, human–hamster hybrid (A_L) cells were exposed to MC-LR for varying lengths of time to investigate the role of nitrogen radicals in MC-LR-induced genotoxicity. The mutagenic potential at the CD59 locus was more than 2-fold higher (p < 0.01) in A_L cells exposed to a cytotoxic concentration (1 μmol/L) of MC-LR for 30 days than in untreated control cells, which was consistent with the formation of micronucleus. MC-LR caused a dose-dependent increase in nitric oxide (NO) production in treated cells. Moreover, this was blocked by concurrent treatment with the NO synthase inhibitor N^G-methyl-l-arginine (l-NMMA), which suppressed MC-LR-induced mutations as well. The survival of mitochondrial DNA-depleted (ρ⁰) A_L cells was markedly decreased by MC-LR treatment compared to that in A_L cells, while the CD59 mutant fraction was unaltered. These results provided clear evidence that the genotoxicity associated with chronic MC-LR exposure in mammalian cells was mediated by NO and might be considered as a basis for the development of therapeutics that prevent carcinogenesis.     

Trends and characteristics of total ozone’and vertical profile in Kunming and Beijing，China

This paper presents the trends of total ozone at Beijing and Kunming areas during the period of 1979 to 1989．The SBUV ozone vertical profile data and the periodic oscillation in upper ozone layers over Beijing area are also described．The results show that the variation of Beijing and Kunming per decade are about-5%and-1.5%．respectively．     

Oxidation of antimony(Ⅲ) in soil by manganese(Ⅳ) oxide using X-ray absorption fine structure

The oxidation of antimony(III) in soils was studied using X-ray absorption fine structure(XAFS)spectra.An andosol soil sample and artificial soil samples(SiO_2 blended with iron(III) hydroxide and manganese(IV) oxide) were used herein.After adding antimony(III) oxide to all soil samples,the oxidation process was observed by recording the XAFS spectra of Sb K-edge,Fe Kedge,and Mn K-edge.The results indicated that manganese(IV) oxide played an important role in the oxidation of Sb(III);however iron(III) hydroxide was not directly related to the reaction.During a 2-hr continuous Sb K-edge X-ray absorption near edge structure(XANES) measurement with an interval of 1 min of one of the artificial soil samples(SiO_2+ MnO_2+ Sb_2O_3),a pseudo-first-order reaction was determined with an average estimated rate of 0.52 ± 0.04 hr-1.Compared to the lower oxidation rate of andosol,it is suggested that because of the low concentration of Mn(IV) in natural soils,the oxidation process of Sb(III) might be relatively slow and require more time to convert Sb(III) to Sb(V).