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Rh2O3/hexagonal CePO4 nanocatalysts for N2O decomposition

Huan Liu, Zhen Ma

《化学科学与工程前沿(英文)》 2017年 第11卷 第4期   页码 586-593 doi: 10.1007/s11705-017-1659-6

摘要: Hexagonal CePO nanorods were prepared by a precipitation method and hexagonal CePO nanowires were prepared by hydrothermal synthesis at 150 °C. Rh(NO ) was then used as a precursor for the impregnation of Rh O onto these CePO materials. The Rh O supported on the CePO nanowires was much more active for the catalytic decomposition of N O than the Rh O supported on CePO nanorods. The stability of both catalysts as a function of time on stream was studied and the influence of the co-feed (CO , O , H O or O /H O) on the N O decomposition was also investigated. The samples were characterized by N adsorption-desorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron microscopy, hydrogen temperature-programmed reduction, oxygen temperature-programmed desorption, and CO temperature-programmed desorption in order to correlate the physicochemical and catalytic properties.

关键词: Rh2O3     CePO4     N2O decomposition    

Effects of Pd doping on N

Mingxin Dong, Jun Wang, Jinxin Zhu, Jianqiang Wang, Wulin Wang, Meiqing Shen

《环境科学与工程前沿(英文)》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0976-9

摘要: N O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N O formation over Pt/BaO/Al O catalyst. Three types of catalysts, Pt/BaO/Al O , Pt/Pd mechanical mixing catalyst (Pt/BaO/Al O +Pd/Al O ) and Pt-Pd co-impregnation catalyst (Pt-Pd/BaO/Al O ) were prepared by incipient wetness impregnation method. These catalysts were first evaluated in NSR activity tests using H /CO as reductants and then carefully characterized by BET, CO chemisorption, CO-DRIFTs and H -TPR techniques. In addition, temperature programmed reactions of NO with H /CO were conducted to obtain further information about N O formation mechanism. Compared with Pt/BaO/Al O , (Pt/BaO/Al O +Pd/Al O ) produced less N O and more NH during NO storage and reduction process, while an opposite trend was found over (Pt-Pd/BaO/Al O +Al O ). Temperature programmed reactions of NO with H /CO results showed that Pd/Al O component in (Pt/BaO/Al O +Pd/Al O ) played an important role in NO reduction to NH , and the formed NH could reduce NO to N leading to a decrease in N O formation. Most of N O formed over (Pt-Pd/BaO/Al O +Al O ) was originated from Pd/BaO/Al O component. H -TPR results indicated Pd-Ba interaction resulted in more difficult-to-reduce PdO species over Pd/BaO/Al O , which inhibits the NO dissociation and thus drives the selectivity to N O in NO reduction.

关键词: NOx storage reduction     Pt/BaO/Al2O3     Pd doping     N2O formation     Optimization    

NiCo2O4@quinone-rich N–C core–shell nanowires as composite electrode for electric double layer capacitor

《化学科学与工程前沿(英文)》 2023年 第17卷 第4期   页码 373-386 doi: 10.1007/s11705-022-2223-6

摘要: The bind-free carbon cloth-supported electrodes hold the promises for high-performance electrochemical capacitors with high specific capacitance and good cyclic stability. Considering the close connection between their performance and the amount of carbon material loaded on the electrodes, in this work, NiCo2O4 nanowires were firstly grown on the substrate of active carbon cloth to provide the necessary surface area in the longitudinal direction. Then, the quinone-rich nitrogen-doped carbon shell structure was formed around NiCo2O4 nanowires, and the obtained composite was used as electrode for electric double layer capacitor. The results showed that the composite electrode displayed an area-specific capacitance of 1794 mF∙cm–2 at the current density of 1 mA∙cm–2. The assembled symmetric electric double layer capacitor achieved a high energy density of 6.55 mW∙h∙cm–3 at a power density of 180 mW∙cm–3. The assembled symmetric capacitor exhibited a capacitance retention of 88.96% after 10000 charge/discharge cycles at the current density of 20 mA∙cm–2. These results indicated the potentials in the preparation of the carbon electrode materials with high energy density and good cycling stability.

关键词: carbon cloth     NiCo2O4 nanowires     core−shell structure     quinone-rich     electric double layer capacitor    

Is atmospheric oxidation capacity better in indicating tropospheric O formation?

《环境科学与工程前沿(英文)》 2022年 第16卷 第5期 doi: 10.1007/s11783-022-1544-5

摘要:

● This study summarizes and evaluates different approaches that indicate O3 formation.

关键词: O3     AOC     O3 formation regime    

N2O emission from a sequencing batch reactor for biological N and P removal from wastewater

Lei SHEN,Yuntao GUAN,Guangxue WU,Xinmin ZHAN

《环境科学与工程前沿(英文)》 2014年 第8卷 第5期   页码 776-783 doi: 10.1007/s11783-013-0586-0

摘要: Nitrous oxide (N O) is a greenhouse gas that can be released during biological nitrogen removal from wastewater. N O emission from a sequencing batch reactor (SBR) for biological nitrogen and phosphorus removal from wastewater was investigated, and the aims were to examine which process, nitrification or denitrification, would contribute more to N O emission and to study the effects of heterotrophic activities on N O emission during nitrification. The results showed that N O emission was mainly attributed to nitrification rather than to denitrification. N O emission during denitrification mainly occurred with stored organic carbon as the electron donor. During nitrification, N O emission was increased with increasing initial ammonium or nitrite concentrations. The ratio of N O emission to the removed ammonium nitrogen (N O-N/NH -N) was 2.5% in the SBR system with high heterotrophic activities, while this ratio was in the range from 0.14% to 1.06% in batch nitrification experiments with limited heterotrophic activities.

关键词: biological nutrient removal     denitrification     greenhouse gas     nitrification     nitrous oxide    

CH4 and N2O emissions from double-rice cropping system as affected by Chinese milk

Heshui XU,Dengyun LI,Bo ZHU,Kai ZHANG,Yadong YANG,Chen WANG,Ying JIANG,Zhaohai ZENG

《农业科学与工程前沿(英文)》 2017年 第4卷 第1期   页码 59-68 doi: 10.15302/J-FASE-2017137

摘要: Chinese milk vetch (CMV) and rice straw (RS) were incorporated into soil to substitute for synthetic N fertilizers and to maintain soil fertility. However, little is known about the integrated impacts of CMV and RS incorporation on CH and N O emissions in double-rice cropping systems in southern China. A field experiment was conducted to estimate the integrated impacts of CMV and RS incorporation in the early- and late-rice seasons on CH and N O emissions. All treatments received uniform N inputs, 6%–37% of which was replaced by CMV and RS crop residue. CMV and/or RS incorporation produced equivalent or slightly more grain yield, while reducing N O emissions by 3%–43%. However, both CMV and RS incorporation increased CH emissions. Annual CH emissions ranged from 321 to 614 kg·hm from CMV and RS amendment treatments, which were 1.5–2.9 times higher than that from synthetic N. Compared with single synthetic N fertilizer, incorporation of CMV and/or RS increased GWP and yield-scaled GWP by 45%–164% and 45%–153%, respectively. Our results demonstrate CMV and RS amendments replacing N fertilizer, maintained stable yield, mitigated N O emission, but enhanced CH emission. Further study is needed on crop residue management in double-cropping rice systems.

关键词: Chinese milk vetch     CH4     double-rice cropping system     grain yield     N2O     rice straw    

Production of N

Youkui GONG,Yongzhen PENG,Shuying WANG,Sai WANG

《环境科学与工程前沿(英文)》 2014年 第8卷 第4期   页码 589-597 doi: 10.1007/s11783-013-0571-7

摘要: The N O production in two nitrogen removal processes treating domestic wastewater was investigated in laboratory-scale aerobic-anoxic sequencing batch reactors (SBRs). Results showed that N O emission happened in the aerobic phase rather than in the anoxic phase. During the aerobic phase, the nitrogen conversion to N O gas was 27.7% and 36.8% of loss for conventional biologic N-removal process and short-cut biologic N-removal process. The dissolved N O was reduced to N in the anoxic denitrification phase. The N O production rate increased with the increasing of nitrite concentration and ceased when oxidation was terminated. Higher nitrite accumulation resulted in higher N O emission in the short-cut nitrogen removal process. Pulse-wise addition of 20 mg gave rise to 3-fold of N O emission in the conventional N-removal process, while little change happened with 20 mg was added to SBR1.

关键词: conventional N-removal process     N2O     short-cut N-removal process     nitrite accumulation     ammonia- oxidizing bacteria (AOB) denitrification    

The performance of nitrate-reducing Fe(II) oxidation processes under variable initial Fe/N ratios: The

《环境科学与工程前沿(英文)》 2021年 第15卷 第4期 doi: 10.1007/s11783-020-1366-2

摘要:

•Bacterially-mediated coupled N and Fe processes examined in incubation experiments.

关键词: Denitrification     N2O emission     Fe(II) oxidation     Fe/N ratio     Fe minerals    

UNREDUCED MEGAGAMETOPHYTE FORMATION VIA SECOND DIVISION RESTITUTION CONTRIBUTES TO TETRAPLOID PRODUCTION

《农业科学与工程前沿(英文)》 2021年 第8卷 第2期

摘要:

Seedless fruits are desirable in the citrus fresh fruit market. Triploid production via diploid × tetraploid interploidy crosses is thought to be the most efficient and widely-used strategy for the breeding of seedless citrus. Although ‘Orah’ mandarin has desirable organoleptic qualities, seeds in the fruits weaken its market competitiveness. To produce new seedless cultivars that are similar to ‘Orah’ mandarin, we performed three 2x × 4x crosses using ‘Orah’ mandarin as the seed parent to regenerate triploid plantlets. A total of 182 triploid and 36 tetraploid plantlets were obtained. By analyzing their genetic origins using nine novel single nucleotide polymorphism (SNP) markers, all of the triploids and tetraploids derived from these three crosses were proven to be hybrids. Also, we demonstrated that 2n megagametophyte formation in ‘Orah’ mandarin result in tetraploid production in these three interploidy crosses. These tetraploid plantlets were genotyped using eight pericentromeric SNP markers and nine centromere distal SNP markers. Based on the genotypes of the 2n megagametophytes, the parental heterozygosity rates in 16 SNP loci and all 2n megagametophytes were less than 50%, indicating that second division restitution was the mechanism underlying 2n megagametophyte formation at both the population and individual levels. These triploid hybrids enrich the germplasm available for seedless breeding. Moreover, the tetraploid hybrids are valuable as parents for ploidy breeding for the production of seedless citrus fruits.

 

关键词: Citrus / 2n gamete / interploidy hybridization / pericentromeric SNP marker / second division restitution    

Physical and chemical processes of wintertime secondary nitrate aerosol formation

Qi YING

《环境科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 348-361 doi: 10.1007/s11783-011-0343-1

摘要: The UCD/CIT model was modified to include a process analysis (PA) scheme for gas and particulate matter (PM) to study the formation of secondary nitrate aerosol during a stagnant wintertime air pollution episode during the California Regional PM /PM Air Quality Study (CRPAQS) where detailed measurements of PM components are available at a few sites. Secondary nitrate is formed in the urban areas from near the ground to a few hundred meters above the surface during the day with a maximum modeled net increase rate of 4 μg·m ·d during the study episode. The secondary nitrate formation rate in rural areas is lower due to lower NO . In the afternoon hours, near-surface temperature can be high enough to evaporate the particulate nitrate. In the nighttime hours, both the gas phase N O reactions with water vapor and the N O heterogeneous reactions with particle-bound water are important for secondary nitrate formation. The N O reactions are most import near the surface to a few hundred meters above surface with a maximum modeled net secondary nitrate increase rate of 1 μg·m ·d and are more significant in the rural areas where the O concentrations are high at night. In general, vertical transport during the day moves the nitrate formed near the surface to higher elevations. During the stagnant days, process analysis indicates that the nitrate concentration in the upper air builds up and leads to a net downward flux of nitrate through vertical diffusion and a rapid increase of surface nitrate concentration.

关键词: secondary nitrate aerosol     N2O5 heterogeneous reaction     process analysis    

Hydroxyl radical intensified Cu

Wenyue Li, Min Chen, Zhaoxiang Zhong, Ming Zhou, Weihong Xing

《环境科学与工程前沿(英文)》 2020年 第14卷 第6期 doi: 10.1007/s11783-020-1281-6

摘要: Abstract • Cu2O NPs/H2O2 Fenton process was intensified by membrane dispersion. • DMAc removal was enhanced to 98% for initial DMAc of 14000 mg/L. • Analyzed time-resolved degradation pathway of DMAc under ·OH attack. High-concentration industrial wastewater containing N,N-dimethylacetamide (DMAc) from polymeric membrane manufacturer was degraded in Cu2O NPs/H2O2 Fenton process. In the membrane-assisted Fenton process DMAc removal rate was up to 98% with 120 min which was increased by 23% over the batch reactor. It was found that ·OH quench time was extended by 20 min and the maximum ·OH productivity was notably 88.7% higher at 40 min. The degradation reaction rate constant was enhanced by 2.2 times with membrane dispersion (k = 0.0349 min−1). DMAc initial concentration (C0) and H2O2 flux (Jp) had major influence on mass transfer and kinetics, meanwhile, membrane pore size (rp) and length (Lm) also affected the reaction rate. The intensified radical yield, fast mass transfer and nanoparticles high activity all contributed to improve pollutant degradation efficiency. Time-resolved DMAc degradation pathway was analyzed as hydroxylation, demethylation and oxidation leading to the final products of CO2, H2O and NO3− (rather than NH3 from biodegradation). Continuous process was operated in the dual-membrane configuration with in situ reaction and separation. After five cycling tests, DMAc removal was all above 95% for the initial [DMAc]0 = 14,000 mg/L in wastewater and stability of the catalyst and the membrane maintained well.

关键词: Ceramic membrane reactor     N     N-dimethylacetamide     Fenton process     Cu2O     Wastewater treatment    

Phylogenetic diversity of NO reductases, new tools for monitoring, and insights into NO production in natural and engineered environments

《环境科学与工程前沿(英文)》 2022年 第16卷 第10期 doi: 10.1007/s11783-022-1562-3

摘要:

● 548 representative nor genes were collected to create complete phylogenetic trees.

关键词: N2O     Greenhouse gas     NO reductase     NO dismutase     Primer     Crystal structure    

New insight into effect of potential on degradation of Fe-N-C catalyst for ORR

Yanyan GAO, Manman QI, Liang HE, Haiping CHEN, Wenzhe LUO, Ming HOU, Zhigang SHAO

《能源前沿(英文)》 2021年 第15卷 第2期   页码 421-430 doi: 10.1007/s11708-021-0727-2

摘要: In recent years, Fe-N-C catalyst is particularly attractive due to its high oxygen reduction reaction (ORR) activity and low cost for proton exchange membrane fuel cells (PEMFCs). However, the durability problems still pose challenge to the application of Fe-N-C catalyst. Although considerable work has been done to investigate the degradation mechanisms of Fe-N-C catalyst, most of them are simply focused on the active-site decay, the carbon oxidation, and the demetalation problems. In fact, the 2e pathway in the ORR process of Fe-N-C catalyst would result in the formation of H O , which is proved to be a key degradation source. In this paper, a new insight into the effect of potential on degradation of Fe-N-C catalyst was provided by quantifying the H O intermediate. In this case, stability tests were conducted by the potential-static method in O saturated 0.1 mol/L HClO . During the tests, H O was quantified by rotating ring disk electrode (RRDE). The results show that compared with the loading voltage of 0.4 V, 0.8 V, and 1.0 V, the catalysts being kept at 0.6 V exhibit a highest H O yield. It is found that it is the combined effect of electrochemical oxidation and chemical oxidation (by aggressive radicals like H O /radicals) that triggered the highest H O release rate, with the latter as the major cause.

关键词: proton exchange membrane fuel cells (PEMFCs)     oxygen reduction reaction (ORR)     Fe-N-C catalyst     potential     H2O2     degradation    

Mechanistic insight into the biofilm formation and process performance of a passive aeration ditch (PAD

《环境科学与工程前沿(英文)》 2022年 第16卷 第7期 doi: 10.1007/s11783-021-1494-3

摘要:

• A Passive Aeration Ditch was developed to treat decentralized wastewater.

关键词: Decentralized wastewater     Passive aeration ditch     Biofilm formation     C/N ratio     Salinity     Model simulation    

Inexpensive synthesis of a high-performance Fe

Nadir Abbas, Godlisten N. Shao, Syed M. Imran, Muhammad S. Haider, Hee Taik Kim

《化学科学与工程前沿(英文)》 2016年 第10卷 第3期   页码 405-416 doi: 10.1007/s11705-016-1579-x

摘要: A sol-gel technique has been developed for the synthesis of a magnetite-silica-titania (Fe O -SiO -TiO ) tertiary nanocomposite with improved photocatalytic properties based on the use of inexpensive titania and silica precursors. The exceptional photocatalytic activity of the resulting materials was demonstrated by using them to photocatalyze the degradation of methylene blue solution. The best formulation achieved 98% methylene blue degradation. An interesting feature of the present work was the ability to magnetically separate and reuse the catalyst. The efficiency of the catalyst remained high during two reuses. The synthesized nanomaterials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, ultra-violet-visible spectroscopy, diffuse reflectance spectroscopy, and thermogravimetric analysis. XRD analysis revealed the formation of multicrystalline systems of cubic magnetite and anatase titania crystals. SEM and TEM characterization revealed well-developed and homogeneously dispersed particles of size less than 15 nm. FTIR spectra confirmed the chemical interaction of titania and silica. It was further noticed that the optical properties of the prepared materials were dependent on the relative contents of their constituent metal oxides.

关键词: sol-gel     photocatalysis     magnetic recovery     TiO2     Fe3O4     SiO2    

标题 作者 时间 类型 操作

Rh2O3/hexagonal CePO4 nanocatalysts for N2O decomposition

Huan Liu, Zhen Ma

期刊论文

Effects of Pd doping on N

Mingxin Dong, Jun Wang, Jinxin Zhu, Jianqiang Wang, Wulin Wang, Meiqing Shen

期刊论文

NiCo2O4@quinone-rich N–C core–shell nanowires as composite electrode for electric double layer capacitor

期刊论文

Is atmospheric oxidation capacity better in indicating tropospheric O formation?

期刊论文

N2O emission from a sequencing batch reactor for biological N and P removal from wastewater

Lei SHEN,Yuntao GUAN,Guangxue WU,Xinmin ZHAN

期刊论文

CH4 and N2O emissions from double-rice cropping system as affected by Chinese milk

Heshui XU,Dengyun LI,Bo ZHU,Kai ZHANG,Yadong YANG,Chen WANG,Ying JIANG,Zhaohai ZENG

期刊论文

Production of N

Youkui GONG,Yongzhen PENG,Shuying WANG,Sai WANG

期刊论文

The performance of nitrate-reducing Fe(II) oxidation processes under variable initial Fe/N ratios: The

期刊论文

UNREDUCED MEGAGAMETOPHYTE FORMATION VIA SECOND DIVISION RESTITUTION CONTRIBUTES TO TETRAPLOID PRODUCTION

期刊论文

Physical and chemical processes of wintertime secondary nitrate aerosol formation

Qi YING

期刊论文

Hydroxyl radical intensified Cu

Wenyue Li, Min Chen, Zhaoxiang Zhong, Ming Zhou, Weihong Xing

期刊论文

Phylogenetic diversity of NO reductases, new tools for monitoring, and insights into NO production in natural and engineered environments

期刊论文

New insight into effect of potential on degradation of Fe-N-C catalyst for ORR

Yanyan GAO, Manman QI, Liang HE, Haiping CHEN, Wenzhe LUO, Ming HOU, Zhigang SHAO

期刊论文

Mechanistic insight into the biofilm formation and process performance of a passive aeration ditch (PAD

期刊论文

Inexpensive synthesis of a high-performance Fe

Nadir Abbas, Godlisten N. Shao, Syed M. Imran, Muhammad S. Haider, Hee Taik Kim

期刊论文