The activities of CeO2 nanocubes calcined at different temperatures were tested for catalytic oxidation of o-xylene. Using CeO2 nanocubes as catalysts, complete catalytic oxidation of o-xylene was achieved below 210℃. The CeO2 nanomaterials were characterized by means of BET, X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and high-resolution transmission electron microscopy （HRTEM）. From the TEM images, all CeO2 nanocubes displayed cubic morphology irrespective of calcination temperature. The HRTEM images revealed that these nanocubes were enclosed by reactive {001} planes, which may contribute to the intrinsically catalytic property of o-xylene oxidation. The higher activity of CeO2 nanocubes calcined at 550℃ than those calcined at above 550℃ was attributed to their smaller crystallite size and larger surface area. The influences of reaction conditions were also studied, which found that a higher reaction temperature was necessary for complete catalytic oxidation of o-xylene at higher weight hourly space velocity （WHSV） and o-xylene concentration.
Correlations between raw water characteristics and pH after enhanced coagulation to maximize dissolved organic matter（DOM） removal using four typical coagulants（FeCl3,Al2（SO4）3,polyaluminum chloride（PACl） and high performance polyaluminum chloride（HPAC）） without pH control were investigated.These correlations were analyzed on the basis of the raw water quality and the chemical and physical fractionations of DOM of thirteen Chinese source waters over three seasons.It was found that the final pH after enhanced coagulation for each of the four coagulants was in？uenced by the content of removable DOM（i.e.hydrophobic and higher apparent molecular weight（AMW） DOM）,the alkalinity and the initial pH of raw water.A set of feed-forward semi-empirical models relating the final pH after enhanced coagulation for each of the four coagulants with the raw water characteristics were developed and optimized based on correlation analysis.The established models were preliminarily validated for prediction purposes,and it was found that the deviation between the predicted data and actual data was low.This result demonstrated the potential for the application of these models in practical operation of drinking water treatment plants.
Jiankun XieDongsheng WangJohn van LeeuwenYanmei ZhaoLinan XingChristopher W. K. Chow
Mineral dust comprises a great fraction of the global aerosol loading,but remains the largest uncertainty in predictions of the future climate due to its complexity in composition and physico-chemical properties.In this work,a case study characterizing Asian dust storm particles was conducted by multiple analysis methods,including SEM-EDS,XPS,FT-IR,BET,TPD/mass and Knudsen cell/mass.The morphology,elemental fraction,source distribution,true uptake coefficient for SO 2,and hygroscopic behavior were studied.The major components of Asian dust storm particles are aluminosilicate,SiO 2 and CaCO 3,with organic compounds and inorganic nitrate coated on the surface.It has a low reactivity towards SO 2 with a true uptake coefficient,5.767×10-6,which limits the conversion of SO 2 to sulfate during dust storm periods.The low reactivity also means that the heterogeneous reactions of SO 2 in both dry and humid air conditions have little effect on the hygroscopic behavior of the dust particles.
The leaching behaviors of enrofloxacin （ENR）, a fluoroquinolone group antibiotic, in three different standard soils, namely sandy, loamy sand and sandy loam were investigated according to OECD guideline 312. In addition, the effects of tenside, sodium dodecylbenzenesulfonate （DBS） on the mobility of ENR in two different soils were studied. The mobility of ENR in all three standard soils was very similar and was mostly （98%） concentrated on the top 0-5 cm segment of the soils at pH 5.7. The DBS can enhance the mobility of ENR in soils but the impact was in general negligible under the studied conditions.
