Search

The diffusion of stubborn oils and organic pigments has become a severe environmental pollution problem. Promisingly, the combination of superhydrophobicity and photocatalysis is expected to provide an efficient, economical and simple solution. In this paper, a kind of superhydrophobic and super-lipophilicity polyurethane (PU)-based sponge was reported by a strategy of undergoing ferric tetroxide loading (Fe3O4@PU), polydopamine fixation (PDA-Fe3O4@PU), octadecylamine grafting (ODA-Fe3O4@PU) and molybdenum disulfide loading (MoS2-ODA-Fe3O4@PU) successively. The results show that the MoS2-ODA-Fe3O4@PU sponge exhibits outstanding superhydrophobicity (with maximum water contact angle of 161.64°), excellent oil absorption capacity (60–109 wt/wt), robust stability in extreme environments and great oil/water separation ability. In addition, the MoS2-loaded sponge demonstrates desirable outcomes in decomposing methyl orange and methylene blue under light source, and a dual-functional purification system with a heterogeneous polyurethane-based sponge (the upper part is MoS2-ODA-Fe3O4@PU and the bottom part is MoS2@PU) endowed with superhydrophobicity and photocatalysis can purify water by separating oils and decomposing methylene blue simultaneously.

Over the past few decades, gold-based materials have drawn extensive attention due to their intriguing physical/chemical properties and excellent performance in a broad range of applications. In particular, the remarkable technical progress in synthesis and characterization is promoting the rapid development of gold-based nanoalloys, which are of great significance in catalysis. In this review, we provide a brief overview of the recently reported gold-based nanoalloys, focusing on their general synthetic methods and potential catalytic applications. In particular, the general relationships between material structures/compositions and catalytic performances are discussed in representative chemical reactions, such as the carbon dioxide reduction reaction (CO2RR), oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), small organic molecule oxidation reaction, carbon monoxide oxidation reaction, and typical heterogeneous catalytic reactions in chemical engineering. Furthermore, critical challenges and potential opportunities facing gold-based nanoalloys are proposed to provide possible inspiration for future material design towards high performance applications.

High mercury (Hg) affects biochemical-physiological characteristics of plant leaves such as leaf chlorophyll, causing refractive discontinuity and modifications in leaf spectra. Furthermore, the hyperspectroscopy provides a potential tool for fast non-destructive estimation of leaf Hg. However, there are few studies that have investigated Hg for wetland plants via hyperspectral inversion. In this study, reeds (Phragmites australis) leaf Hg concentration and hyperspectra were measured under different soil Hg treatment. Hg-sensitive parameters were identified by basic spectral transformations and continuous wavelet transformation (CWT). Inversion models were developed using stepwise multiple linear regressions (SMLR), partial least square regression (PLSR), and random forest (RF) to estimate leaf Hg. The results indicated that CWT improved the correlation of hyperspectra and leaf Hg by 0.020–0.227, and R2 of the CWT-related model increased by 0.0557–0.2441. In addition, Hg-sensitive bands were predominant at 600–750 (visible region) and 1500–2300 nm (mid-infrared), and Hg might modify leaves spectra primarily by affecting chlorophyll and water contents. Of the studied models, SMLR using normalized transformation (NR) and CWT (NR-CWT-SMLR) model (R2 = 0.8594, RMSE = 0.0961) and RF using NR and CWT (NR-CWT-RF) model (R2 = 0.8560, RMSE = 0.1062) suited for leaf Hg inversion. For Hg content

Nitrogen is an essential nutrient for plant growth and development. Rapid and nondestructive monitoring of nitrogen nutrition in plants using hyperspectral remote sensing is important for accurate ...

Three kinds of SiCp/Al-Si-Mg composites, containing 20%, 40% and 60% volume fraction of silicon carbide particles (SiCp) were respectively sintered at high cubic anvil pressure, using SiC p...

Introduction : High mercury (Hg) concentrations affect the chlorophyll in leaves, thereby modifying leaf spectra. Hyperspectra is a promising technique for the rapid, nondestructive evaluation of leaf Hg content. In this study, we investigated Hg contents and reflective hyperspectra of reed leaves ( Phragmites communis ) in a gold mining (Jilin province, China). Spectral parameters sensitive to Hg content were identified through basic spectral transformations, continuous wavelet transformation (CWT), and spectral indices techniques. Leaf Hg inversion models were developed using stepwise multiple linear regression, partial least squares regression, and random forest algorithms. Outcomes : The results indicated that: 1) leaf Hg content decreased with increasing distance from the mine: Jiapigou (JPG) > Erdaocha (EDC) > Laojingchang (LJC) > Erdaogou (EDG) > Lingqian (LQ) > Weishahe (WSH). 2) Hg–sensitive wavelengths were primarily in the visible region; CWT increased the correlation between hyperspectral data and leaf Hg content, and improved the regression and accuracy of inversion; 3) the continuum removal–CWT–stepwise multiple linear regression was better for estimating low leaf Hg content; while the differential spectral index–partial least squares regression was better for estimating high leaf Hg content. Conclusion : These hyperspectral inversion methods could be used for rapid, nondestructive monitoring of wetland plants.

Three-dimensional porous sponge has been demonstrated as an outstanding candidate in oil/water separation due to its hydrophobicity and oleophilicity that originates from the synergistic effect of rough structure and low surface energy, but the separation process has not been illuminated clearly. This paper presents the study of the synthesis of oil/water separation sponge, mechanism of separation process and establishment of kinetic model, via the combination among dopamine chemistry, covalent modification, theoretical analysis, experimental results and mathematical model. Results show that both the dopamine deposition time and the octadecyltrimethoxysilane hydrolysis system significantly affect the hydrophobicity of the modified-melamine sponge and that the oil/water separation process is composed of six scenarios with different physical state. Furthermore, with the experimental results, established iso-potential separation model and the height-quantized model, we conclude that the time-dependent separation patterns and kinetics are subjected to the modulation of the viscosity of the separated substance and the immersion depth of the sponge.

The massive use of renewable energy has driven the development of energy storage. Compressed CO2 energy storage technology is a promising technology. To gain a deeper understanding of the process of compressing carbon dioxide energy storage (CCES) technology, in order to support technological advances, this paper experimentally studied the performance of compressed CO2 energy storage system. The key parameters, such as the pressure of the storage tanks, the power consumption of the compressor, and the power of the expander were investigated.

Oxy-fuel combustion is one of potential technologies for carbon dioxide (CO2) capture in fossil fuel fired power plants. Characterization of flue gas composition in the oxy-fuel combustion differs ...

Oxyfuel combustion is a leading potential CO2 capture technology for power plants. As the flue gas (FG) consists of mainly H2O and CO2, a simpler and more energy-efficient CO2 purification method can be used instead of the standard amine-based chemical absorption approach. For the system of oxyfuel combustion with cryogenic CO2 purification, decreasing the oxygen purity reduces the energy consumption of the Air Separation Unit (ASU) but increases the energy consumption for the downstream cryogenic purification. Thus there exists a trade-off between the energy consumption of the ASU and that for cryogenic purification. This paper investigates the potential efficiency improvement by optimizing this trade-off. The simulated results show that there exists an optimum flue gas condensing pressure for the cryogenic purification, which is affected by the flue gas composition. In addition, decreasing the oxygen purity reduces the combined energy consumption of the ASU and the cryogenic purification, and therefore can improve the electrical efficiency. In summary, prior oxyfuel combustion analyses have assumed a high oxygen purity level of 95 mol% or 99 mol% for the combustion air, which achieves a high CO2 concentration in the flue gases. In this Paper, we demonstrate that a lower level of oxygen purity, such as 80 mol%, in conjunction with a more extensive cryogenic purification of the flue gases can lower the total energy consumption, thereby yielding a significant benefit. However, for oxygen purity levels lower than 75 mol%, it may not be possible to still use the two-stage flash system shown here to achieve a CO2 purity of 95 mol% and a CO2 recovery rate of 90% simultaneously.

This study was carried out in the Gurbantunggut Desert, Uygur Autonomous Region of Xinjiang, Northwest China in August, 2009. To quantify the storage, contribution and vertical distribution patterns of plant biomass carbon (PBC) and soil organic carbon (SOC) in the study area, we investigated the carbon concentrations and its vertical distribution in three different desert shrubland communities dominated by Reaumuria soongorica, Haloxylon ammodendron + R. soongorica and Tamarix ramosissima + R. soongorica, respectively. We analyzed vertical distribution of root biomass carbon and soil carbon contents by excavating soil profiles for each dominated community. The results show that SOC is considerably the larger carbon pool in the soil layers of 1.0–3.0 m (the mean value of three shrubland communities is 38.46%) and 3.0–5.0 m (the mean value is 40.24%). In contrast, 70.74% of belowground biomass carbon storage in 0–1.0 m layer, and its content decrease with increasing soil depth. The Haloxylon ammodendron + R. soongorica shrubland community has the highest belowground biomass carbon among three selected communities. This study highlights the importance of SOC stored in deep soil layers (lower than 3.0 m from the surface) in arid shrubland communities in the global carbon balance. In addition, it provides the data support for revealing deep soil solid carbon potential, and offers scientific basis for the further research in the carbon cycle of terrestrial ecosystem.

This paper examined and assessed various configuration options about emission removal including particles. SOx and NOx in an oxy-coal combustion system for CO2 capture. A performance analysis was c ...

A recent study (Wolf et al., 2010) suggests that short—lived pulses of N2O emission during spring thaw dominate the annual N2O budget and that grazing decreases N2O emissions during the spring thaw. To verify this we conducted year—round N2O flux measurements from June 2010 to May 2011 in Tianshan alpine grassland in central Asia. No pulse emissions of N2O were found at grazing management sites and nitrogen addition sites during the spring thaw. The contribution of the spring thaw to the total annual N2O budget was small and accounted for only 6.6% of the annual fluxes, with winter emissions accounting for 16.7% and growing season emissions accounting for 76.7%. The difference in N2O emissions attributable to grazing management was not significant (P > 0.05). Nitrogen input tended to increase N2O emissions at N addition sites during the grass growing season compared with those at unfertilized sites. N2O fluxes showed a significant correlation with air temperature and also with both soil temperature and soil water content at 10 cm depth.

Oxy-coal combustion is one of the technical solutions for mitigating CO2 in thermal power plants. For designing a technically viable and economically effective CO2 capture process, effects by coals ...

This paper studied the integration of Evaporative Gas Turbine (EvGT) cycle with oxy-fuel combustion for CO2 capture. The impact of key parameters on system electrical efficiency, such as the oxygen ...

This article studied the integration of an evaporative gas turbine (EvGT) cycle with chemical absorption for CO2 capture. Two systems of EvGT cycle without CO2 capture and EvGT cycle with CO2 captu ...

Oxyfuel combustion is one of the technologies for carbon dioxide (CO2) capture and storage (CCS) in fossil-fuel-based power systems to mitigate global greenhouse gas (GHG) emissions. When introducing oxyfuel combustion into the power systems, physical and chemical processes of the combustion differ from conventional combustion, and the energy penalty for CCS has significant impacts on the system operation and performance, similar to combustion process, heat transfer, flue gas properties, and emission control. Around these topics, dozens of oxyfuel-related projects were launched within this decade in the worldwide, and many techno-economic assessments for oxyfuel technology including competitive technologies (pre-/post-combustion and emerging technologies) are continuously being published. Although the technologies for oxyfuel combustion are relatively well understood today, it is only investigated experimentally in lab and pilot-scale combustion equipment. The estimated costs of electricity and CO2 avoidance costs are varied by uncertainties from economical assessments from different referenced databases and from restricted regulation of different countries and regions. Therefore, all addressed issues must be clarified and proved to be feasible deployment for the commercial scale CCS plants to cope with emission targets according to Copenhagen Accord to reduce GHG emission and mitigate world temperature rising. Keywords: oxyfuel combustion; CO2 capture; air separation; flue gas recycle; greenhouse gases; steam cycle; combined cycle

Previous work has failed to address fully the response of (autotrophic and heterotrophic) respiration to grazing and nitrogen (N) addition in different ecosystems, particularly in alpine grasslands outside the growing season. From 2010 to 2011, we combined two methods (static closed chambers and a closed dynamic soil CO2 flux system) in a controlled field experiment in an alpine grassland in the Tianshan Mountains. We examined the effects of grazing and N application on ecosystem respiration (Re) both outside (NGS) and during (GS) the growing season and determined the pattern of Re in relation to climate change. There was no significant change in CO2 emissions under grazing or N application. Heterotrophic respiration (Rh) accounted for 78.5% of Re. Re, Rh and autotrophic respiration (Ra) outside the growing season were equivalent to 12.9, 14.1 and 11.4% of the respective CO2 fluxes during the growing season. In addition, our results indicate that precipitation (soil water content) plays a critical role in Ra in this cold and arid environment. Both Rh and Re were sensitive to soil temperature. Moreover, our results suggest that grazing and N addition exert no significant effect on CO2 emissions in alpine grassland but may alter soil carbon stocks in alpine grassland.

Arid areas play a significant role in the global nitrogen cycle. Dry and wet deposition of inorganic nitrogen (N) species were monitored at one urban (SDS) and one suburban (TFS) site at Urumqi in a semi-arid region of central Asia. Atmospheric concentrations of NH3, NO2, HNO3, particulate ammonium and nitrate (pNH4 (+) and pNO3 (-)) concentrations and NH4-N and NO3-N concentrations in precipitation showed large monthly variations and averaged 7.1, 26.6, 2.4, 6.6, 2.7 µg N m(-3) and 1.3, 1.0 mg N L(-1) at both SDS and TFS. Nitrogen dry deposition fluxes were 40.7 and 36.0 kg N ha(-1) yr(-1) while wet deposition of N fluxes were 6.0 and 8.8 kg N ha(-1) yr(-1) at SDS and TFS, respectively. Total N deposition averaged 45.8 kg N ha(-1) yr(-1)at both sites. Our results indicate that N dry deposition has been a major part of total N deposition (83.8% on average) in an arid region of central Asia. Such high N deposition implies heavy environmental pollution and an important nutrient resource in arid regions.

Dry and wet deposition of inorganic nitrogen species were monitored at one urban (SDS) and one rural (TFS) site during September 2009 and August 2010 at Urumqi in a semi-arid region. Atmospheric concentrations of NH3, NO2, HNO3, particulate ammonium and nitrate (pNH4+ and pNO3-) concentrations and NH4-N and NO3-N concentrations in precipitation showed large monthly variations and averaged 7.0, 18.2, 2.4, 6.6, 2.7 µg N m-3 and 1.3, 1.0 mg N L-1 at both SDS and TFS. Nitrogen dry deposition fluxes were 32.8 and 28.9 kg N ha-1 yr-1 while wet deposition of N fluxes were 6.0 and 8.8 kg N ha-1 yr-1 at SDS and TFS, respectively. Our results indicate that N dry deposition has been a major part of total N deposition (80.6% on average) in the semi-arid region. Such high N deposition implied the heavy environmental pollution and an important nutrient resource in arid and semi-arid regions.

To assess the effects of nitrogen (N) deposition on greenhouse gas (GHG) fluxes in alpine grassland of the Tianshan Mountains in central Asia, CH(4), CO(2) and N(2)O fluxes were measured from June 2010 to May 2011. Nitrogen deposition tended to significantly increase CH(4) uptake, CO(2) and N(2)O emissions at sites receiving N addition compared with those at site without N addition during the growing season, but no significant differences were found for all sites outside the growing season. Air temperature, soil temperature and water content were the important factors that influence CO(2) and N(2)O emissions at year-round scale, indicating that increased temperature and precipitation in the future will exert greater impacts on CO(2) and N(2)O emissions in the alpine grassland. In addition, plant coverage in July was also positively correlated with CO(2) and N(2)O emissions under elevated N deposition rates. The present study will deepen our understanding of N deposition impacts on GHG balance in the alpine grassland ecosystem, and help us assess the global N effects, parameterize Earth System models and inform decision makers.

Pre-combustion capture technology is a promising route to power generation with CO 2 free emissions, by transforming the fossil hydrocarbon fuel into a hydrogen rich fuel with near zero Carbon containing species. This gaseous fuel also allows to use a high efficiency gas turbine into a coal based power plant. The gas turbine combustor however has to meet the challenge of high temperature flame responsible for unacceptable NOx emissions, and a highly reacting fuel impeding the use of conventional dry low NOx combustion technologies. The actual solution to this problem is to dilute the hydrogen fuel with up to 50% Nitrogen. This paper presents a concept where the exhaust gas of the gas turbine is recirculated (EGR) such as to deplete the air of oxygen to produce a low temperature combustion with undiluted hydrogen fuel while flame stability is still ensured by the highly reactive properties of hydrogen. The study compares the concept with a cycle using Selective Catalytic Reduction for NOx control.