Efficient low-temperature soot combustion by bimetallic Ag–Cu/SBA-15 catalysts

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.     

Removal of hydrophobic volatile organic compounds with sodium hypochlorite and surfactant in a co-current rotating packed bed

A co-current flow rotating packed bed was applied to remove volatile organic compounds(VOCs) by sodium hypochlorite(Na Cl O) and surfactant(sodium dodecyl benzene sulfonate,SDBS) from air stream. Xylene was used as a model VOC herein. The effect of p H,concentration of Na Cl O and SDBS solution, liquid flow rate, gas flow rate and rotational speed on xylene removal efficiency and overall mass transfer coefficient(KGa) were discussed. Then, a correlation for KGa of the co-current rotating packed bed was proposed by fitting the experimental data of KGa and independent variables of liquid/gas ratio,rotational speed, p H, Na Cl O concentration and treatment time, which was in good agreement with the experimental data(the deviation ≤± 30%).     

土壤作物系统镉污染及其防治研究

选择我国北方主要粮食作物冬小麦和夏谷进行盆栽试验，研究了土壤镉污染对作物生长发育和产量的影响及泥炭、羊粪两种不同类型的有机肥缓减土壤镉污染危害的作用；分析了镉在两种作物不同器官中的迁移效率和累积规律；认为施加有机肥是缓减土壤镉污染危害的有效措施，且施羊粪的效果比施泥炭好。     

北方人工湿地系统对内分泌干扰物质的去除效果

通过现场取样,固相萃取柱富集以及气相色谱/质谱联用(GC/MSD)测定,研究了北京市官厅水库上游的一个人工湿地系统在秋季(植物茂盛)和冬季(植物枯萎)对典型环境内分泌干扰物和人工合成激素的处理效果.结果表明,人工湿地系统的原水和各工艺段出水中酚类和雌激素类物质的浓度高于美国地表水监测数据和我国地表水监测数据.湿地系统对部分壬基酚有较好的处理效果,而在冬季效果不明显;无论秋季或冬季对雌激素类则无明显去除效果.     

芳香族醛酮化合物溶解度和分配系数的测定与估算

本文测定了１５种芳香族醛酮化合物的溶解度和正辛醇－水分配系数,研究了水溶解度及分配系数与分子连接性能指数的相关性。结果表明,溶解度和分配系数之间以及与分子连接性指数呈较好的线性关系。     

光子相关光谱（PCS）在无机高分子絮凝剂形态表征中的应用

本文运用现代先进的微粒检测手段光子相关光谱对常见的两类无机高分子絮凝剂的形态进行了表征。实验结果表明：在所测聚合氯化铁溶液中，体系呈较为单一的集中分布，由平移扩散系数计算得到平均有效直径在５－１１ｎｍ左右。在所测聚合氯化铝溶液中，主要为双峰分布，熟化后样品约为２－５ｎｍ的小颗粒与数十ｎｍ以上分布较宽的聚集体，另外，本文对光子相关光谱在形态表征中的优缺点及其它应用的可能性也作了一定的论述。     

Field studies on 32P movement and P leaching from flooded paddy soils in the region of Taihu Lake, China

Field experiments were done in two sites, Yixing and Changshu, Jiangsu province, China, to study P movement and leaching in flooded paddy soils. P movement in soil was investigated by using the KH2 32PO4 tracker method, and the amount of P leached from the soil layer in different depths was estimated by measuring P concentrations in the soil solution and saturated hydraulic conductivities in field. Determination was done about one month after P application. There was 46% and 42% of total 32P retained in the 0-5cm layer of soil in the Yixing site and in the Changshu site respectively. The 32P retained in the 25-30 cm layer was only about 1-2% of the total 32P added. Furthermore, 8.01% of 32P in the soil of Yixing site and 16.8% of 32P in the soil of Changshu site was lost from the layer 0-30 cm soil. The seasonal amounts of P leached from the top soil layer and from bottom layer are about 4.5-5.8% and 1.6-2.1% of the total P application, respectively. Changes of total P concentrations in soil solutions during rice growth showed that the fertilizer P applied before flooding of the paddy fields suffered a flash leaching loss and a slow leaching loss. We concluded that the fertilizer P could quickly move in the flooded paddy rice field and parts of it can enter into surface water and ground water. Unless the P application is well managed the risk of P loss and consequently environmental pollution exist.     

The gas-photocatalytic degradation of trichloroethylene without water

The photocatalytic degradation of gaseous trichloroethylene (TCE) without water has been studied. The degradation products were determined to be CO₂, HCl and Cl₂, and the reaction stoichiometry, was described as

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. The degradation rate was found to be linear with 0.16 power of the illumination intensity. When the TCE concentration was low (10¹⁴ mol L⁻¹ or a little more), its degradation rate model could be considered as first order kinetics. A mechanism of valence band hole oxidation was proposed.     

Effects of redox potential and pH value on the release of rare earth elements from soil

Equilibrium release experiments were conducted under three different pH values of 3.5, 5.5 and 7.5 as well as three redox potentials of 400, 0 and -100 Mv to investigate the influence of redox potential and pH value on the La, Ce, Gd and Y release of from the simulated-REEs-accumulation (SRA) soil. Oxygen and nitrogen were allowed to flow into soil suspension to adjust redox potential to a preset value, and 1 mol/l HCl or 1 mol/l NaOH solutions were added into the soil suspension to keep pH at a preset value. Results indicated that La, Ce, Gd and Y release increased gradually with the decrease of pH value or Eh, and the influence of redox potential on Ce was more remarkable than on La, Gd and Y. At the same time. It was observed that La, Ce, Gd and Y releases were positively correlated with the release of Fe and Mn, indicating that La, Ce, Gd and Y releases might originate from dissolution of Fe-Mn oxyhydroxides under reduction and low pH conditions. Moreover, it was found that alteration of pH value and redox potential might affect the change of La, Ce, Gd and Y species in the soil. The contents of La, Ce, Gd and Y in exchangeable fraction and Fe-Mn oxide fraction in the solid phase from soil suspension separation decreased with the decline of pH value and redox potential. Multiple stepwise regression analysis showed that exchangeable fraction and Fe-Mn oxide fraction predominately contributed to the La, Ce, Gd and Y release. Low pH value and redox potential were more favorable to La, Ce, Gd and Y releases following the change of their species. The La, Ce, Gd and Y contents in exchangeable fraction and Fe-Mn oxide fraction are the main contributors to their release.