In this study, the effects of copper(Cu) additive on the catalytic performance of Ag/SBA-15 in complete soot combustion were investigated. The soot combustion performance of bimetallic Ag–Cu/SBA-15 catalysts was higher than that of monometallic Ag and Cu catalysts. The optimum catalytic performance was acquired with the 5 Ag_1-Cu_(0.1)/SBA-15 catalyst, on which the soot combustion starts at T_(ig)= 225°C with a T_(50)= 285°C. The temperature for 50% of soot combustion was lower than that of conventional Ag-based catalysts to more than 50°C(Aneggi et al., 2009). Physicochemical characterizations of the catalysts indicated that addition of Cu into Ag could form smaller bimetallic Ag–Cu nanolloy particles, downsizing the mean particle size from 3.7 nm in monometallic catalyst to 2.6 nm in bimetallic Ag–Cu catalyst. Further experiments revealed that Ag and Cu species elicited synergistic effects, subsequently increasing the content of surface active oxygen species. As a result, the structure modifications of Ag by the addition of Cu strongly intensified the catalytic performance. 相似文献
Returning farmland to forests is important for the protection of ecological values. Eucommia ulmoides is considered to be a suitable species for reforestation in the hilly red soil region of southern China. The objective of this study was to investigate the relationship between the water supply and demand of an E. ulmoides plantation to provide insights into the feasibility of large-scale planting for ecological restoration and forest management activities in the hilly red soil region of southern China. With the measured precipitation, surface runoff and interflow and actual evapotranspiration (ETc) estimated by the modified P–M model, soil water storage (SWS) was estimated based on the water balance equation. Monthly variations of SWS were then compared with in situ measured SWS. The results showed that the estimated mean monthly water losses (the sum of the surface runoff, interflow and ETc) were 139.8 mm in a wet year and 120.0 mm in a dry year, while the measured mean monthly water input values (net precipitation) were 131.2 mm in a wet year and 70.8 mm in a dry year. Net soil water storage (ΔSWS) was negative in each month of the growing season in a dry year, but the soil water deficit was replenished during the following season. The model performance showed that the modified P–M model can be adapted to estimate the soil water storage in other forest catchments where no adequate in situ data are available. As a result of estimating the water balance and observing soil water storage in two different hydrological years, E. ulmoides is recommended as a suitable forest rehabilitation species in the study area, and a suitable plant region has been defined by the GIS technique based on the water balance model. 相似文献
Simazine sorption to corn straw biochars prepared at various temperatures (100-600 °C) was examined to understand its sorption behavior as influenced by characteristics of biochars. Biochars were characterized via elemental analysis, BET-N2 surface area (SA), FTIR and 13C NMR. Freundlich and dual-mode models described sorption isotherms well. Positive correlation between log Koc values and aromatic C contents and negative correlation between log Koc values and (O + N)/C ratios indicate aromatic-rich biochars have high binding affinity to simazine (charge transfer (π-π*) interactions) and hydrophobic binding may overwhelm H-bonding, respectively. Dual-mode model results suggest adsorption contribution to total sorption increases with carbonization degree. Positive correlation between amounts of adsorption (Qad) and SA indicates pore-filling mechanism. Comparison between our results and those obtained with other sorbents indicates corn straw biochars produced at higher temperature can effectively retain simazine. These observations will be helpful for designing biochars as engineered sorbents to remove triazine herbicides. 相似文献
An updated systematic review was conducted to assessing on the association between indoor air pollution caused by household energy consumption and childhood pneumonia in low- and middle-income countries. We performed a meta-analysis from the electronic databases of PubMed, Cochrane library, Web of Science, EMBASE. Studies were selected when they reported childhood pneumonia or ALRI in relation to indoor air pollution resulted from solid fuel. Studies must provide results on exposure prevalence of children aged below 5 years from Asia or Africa. We devoted ourselves to identifying randomized controlled experiments and observational epidemiological researches, which revealed the relation between household usage of solid fuel and childhood pneumonia. Among 1954 articles, 276 were reviewed thoroughly and 16 conduced to such a meta-analysis. It was found that there is a significant relationship between the solid fuel combustion and increasing risk of childhood pneumonia (OR?=?1.66, 95%CI 1.36–2.02). The summary odds ratios from biomass use and mixed fuel use were, respectively, 1.86 (95%CI 1.15–3.02) and 1.58 (95%CI 1.38–1.81), with substantial between study heterogeneity (I2?=?87.2% and 29.2%, respectively). According to the subgroup analysis along with the meta-regression analysis, the risk of using solid fuel in Asian regions is higher than that in African regions. Studies based on non-hospital participates (I2?=?49.5%) may also a source of heterogeneity. We found that indoor air pollution generated by the usage of solid fuel might be a significant risk factor for pneumonia in children and suggested improving the indoor air quality by promoting cleaner fuel will be important in undeveloped countries.