炭基载体含氧基团对Mn-Ce双金属吸附剂脱硫活性的影响

以无烟煤、烟煤、褐煤以及工业半焦、烟煤半焦为载体,采用超声辅助加压浸渍法制备了Mn-Ce双金属吸附剂。利用固定床装置对吸附剂的烟气脱硫活性进行了评价,并运用BET、XRD和FTIR技术对其进行了表征。结果表明：吸附剂的脱硫活性主要由焙烧后的金属氧化物提供,金属离子本身无脱硫活性;炭基载体中的酯基是影响金属组分脱硫活性的主要因素,酯基在焙烧过程中分解使得金属组分暴露出来,提高了吸附剂的脱硫活性;中等变质程度的烟煤是制备吸附剂的良好载体,含有适量酯基,使得吸附剂表面金属组分分散均匀。     

氨基介孔磁性载体在柴油生物脱硫中的应用

制备了氨基介孔磁性载体(AMMC),分别采用FTIR,XRD,TEM等技术对AMMC的官能团、磁性、表观形态和沉降性能等进行了表征,并将脱硫菌株固定于AMMC上,以含二苯并噻吩(DBT)的正十六烷为模拟柴油,比较了固定化脱硫菌和游离脱硫菌对柴油的脱硫性能。表征结果显示,AMMC负载了氨基,是具有丰富孔结构的磁性载体(比表面积为61 m~2/g、孔体积为0.131 cm~3/g、平均孔径为11.339 nm),具有悬浮能力强、磁性良好、分离速度快的特点。脱硫实验结果表明:AMMC固定化脱硫菌配合吐温80使用,对DBT的降解率最高,脱硫反应第3天,DBT降解率为75%;AMMC固定化脱硫菌未经活化直接第5次重复使用时,DBT降解率维持在30%左右,游离脱硫菌的DBT降解率不足10%。     

活性碳纤维改性技术研究进展

介绍了活性碳纤维(ACF)的孔结构及表面官能团,综述了国内外ACF改性技术的研究现状.ACF的改性主要包括孔结构调控和表面化学改性,表面化学改性包括氧化还原法、表面负载法、浸渍法、热处理法、远程等离子体处理法、微波辐照法等,也可将多种方法结合来对ACF进行改性,以改善和提高ACF的吸附性能.在总结现有研究的基础上,对ACF改性技术发展趋势进行了展望.     

铁/锰氧化物改性碳基催化剂的制备及其对甲苯的脱除性能

以甘蔗渣为原料,采用水热合成法制备了水热炭,再通过浸渍法负载上铁或锰的氧化物,得到具有吸附-催化氧化双功能的铁/锰氧化物改性碳基催化剂CMF,对催化剂进行了表征,并考察了其对甲苯的脱除性能.表征结果显示,CMF具有比表面积大、活性成分分布均匀等良好的表面结构.实验结果表明:CMF具有较高的甲苯脱除性能,当温度高于250...     

石灰石/石膏湿法烟气脱硫装置的除尘性能

通过对国电太原第一热电厂16号50MW机组石灰石／石膏湿法烟气脱硫装置的除尘性能分析，研究脱硫装置的除尘机理，找出影响FGD除尘性能的主要因素，为烟气脱硫工程设计提供参考。     

氧化亚氮分解催化剂的研究进展

对近年来N2O分解反应催化剂的研究进行了综述,包括离子交换分子筛、过渡金属氧化物、负载型贵金属等催化剂.对于离子交换分子筛催化剂而言,分子筛骨架结构、交换离子类型、制备方法均对催化剂的活性有一定影响.在过渡金属氧化物催化剂中,Co-A1、Co-Mn-A1等类水滑石衍生复合氧化物的比表面积和催化活性均较高,在其表面添加适量的碱金属或碱土金属助剂可进一步提高催化活性.在贵金属催化剂中,还原型载体负载的催化剂活性较高.Co基复合氧化物负载Au催化剂有望成为实用型的N2O低温分解催化剂.     

生物质吸附剂处理活性艳红X-3B废水

采用城市污水处理厂二沉池的剩余活性污泥为原料，以浓度为3mol／L的ZnCl2溶液浸泡污泥，采用水蒸气为活化气和保护气，在600℃下活化污泥3h，制备出性能良好的生物质吸附剂，其碘吸附值为388．95mg／g，比表面积为447．79m^2／g，平均孔径为4．39nm，孔体积为0．31cm^3／g，微孔体积为0．09cm^3/g。实验结果表明，用该生物质吸附剂处理活性艳红X-3B废水，在废水（10mL）中活性艳红X-3B质量浓度为300mg／L、生物质吸附剂加入量为0．20g、吸附时间为30min的条件下，废水脱色率可达99．7％。活性艳红X-3B在生物质吸附剂上的吸附行为遵循Lagergren二级动力学规律，同时也可用一级吸附动力学方程描述。     

负载金属改性活性炭纤维的脱硫性能

采用浸渍法将金属负载到活性炭纤维(ACF)上对其进行改性,研究了负载金属改性ACF对模型油(二苯并噻吩-正辛烷)的吸附脱硫效果,对比了不同单金属和复合金属盐改性ACF的脱硫性能。实验结果表明:Ag和Zn复合改性的ACF具有最好的脱硫性能;在吸附温度为40℃,吸附时间为2.5 h,油剂质量比为21.5的优化条件下,脱硫率高达97.55%,且具有良好的重复利用性。     

用白泥和赤泥制备烟气脱硫剂

以碱厂白泥和钢厂赤泥为主要原料,研究了制备复合金属氧化物成型烟气脱硫剂的工艺;考察了m（白泥）：m（赤泥）、白泥和赤泥平均粒径、黏结剂、造孔剂对脱硫剂活性的影响。脱硫剂最佳制备工艺条件为m（白泥）：m（赤泥）=2：1,白泥和赤泥粒径越小越好,黏结剂为Na,造孔剂为Zb,加水混匀,挤条成型,烘干后高温焙烧制得;脱硫剂的最高脱硫率为99．83％,脱硫剂脱硫12．30h后穿透硫容为15．20％。     

介孔TiO2纤维的制备及其光催化性能

采用溶胶-凝胶和水蒸气活化热处理技术制备了介孔TiO2纤维,考察了各种因素对介孔TiO2纤维光催化活性的影响,并对介孔TiO2纤维结构进行了表征。介孔TiO2纤维的最佳制备条件：n（TBOT）∶n（C6H10O3）∶n（H2O）∶n（C3H8O）=1∶0.4∶2.0∶16,搅拌时间80min,Si与Ti的摩尔比为0.15,采用分段程序升温工艺,活化温度为700℃。所得介孔TiO2纤维比表面积为127.7m2/g,最可几孔径为7.3nm,具有极高的热稳定性及抗晶型转变能力,反应时间75min时活性艳红X-3B降解率为99.3%。     

Distribution of Cd,Ck, Pb and Zn in Soil and Vegetation Compartments in Stands of Five Boreal Tree Species in N.E. Sweden

Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.     

Starch-plastic materials—Preparation,physical properties,and biodegradability (a review of recent USDA research)

Recent starch-plastic research at the National Center for Agricultural Utilization Research is reviewed and related worldwide efforts are noted. Properties of starch that influence its formulation and performance in plastics are discussed. Methods are given for preparation of starch-poly(methyl acrylate) graft copolymer, starch-poly(ethylene-co-acrylic acid), and starch-poly(ethylene-co-acrylic acid)-polyethylene plastics. Their physical properties are discussed, as is degradability by enzymes or amylolytic organisms from soil, ponds, and streams.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

四氮唑废水处理工艺设计

高浓度、高盐分的四氮唑生产废水通过三效蒸发浓缩,馏出液经铁炭氧微电解和混凝预处理,再采用水解酸化一接触氧化一反应二沉主体组合工艺进行处理。研究了该工艺所需构筑物和设备的设计与选型。该工艺在正常运行条件下,处理后出水pH6～9,COD 302mg／L,BOD5 108mg／L,SS30mg／L,色度36倍,水质达到GB8978--1996（污水综合排放标准》三级标准。     

Application of Cellulose Microfibrils in Polymer Nanocomposites

Cellulose microfibrils obtained by the acid hydrolysis of cellulose fibers were added at low concentrations (2–10% w/w) to polymer gels and films as reinforcing agents. Significant changes in mechanical properties, especially maximum load and tensile strength, were obtained for fibrils derived from several cellulosic sources, including cotton, softwood, and bacterial cellulose. For extruded starch plastics, the addition of cotton-derived microfibrils at 10.3% (w/w) concentration increased Young’s modulus by 5-fold relative to a control sample with no cellulose reinforcement. Preliminary data suggests that shear alignment significantly improves tensile strength. Addition of microfibrils does not always change mechanical properties in a predictable direction. Whereas tensile strength and modulus were shown to increase during addition of microfibrils to an extruded starch thermoplastic and a cast latex film, these parameters decreased when microfibrils were added to a starch–pectin blend, implying that complex interactions are involved in the application of these reinforcing agents.     

Bioassessment of silvicultural impacts in streams and wetlands of the Eastern United States

Bioassessment is a useful tool to determine the impact of logging practices on the biological integrity of streams and wetlands. Measuring biota directly has an intuitive appeal for impact assessment, and biota can be superior indicators to physical or chemical characteristics because they can reflect cumulative impacts over time. Logging can affect stream and wetland biota by increasing sedimentation rates, altering hydrologic, thermal, and chemical regimes, and changing the base of food webs. Biotic impacts of logging on streams compared to wetlands probably differ, and in this paper we review some of those differences. In streams, invertebrates, fishes, amphibians, algae, and macrophytes have been used as indicators of logging impacts. In wetlands, bioassessment is just beginning to be used, and plants and birds are the most promising indicator taxa. Various best management practices (BMPs) have been developed to reduce the impacts of logging on stream and wetland biota, and we review quantitative studies that have evaluated the efficacy of some of these techniques in streams and wetlands in the eastern United States. Remarkably few studies that address the overall efficacy of BMPs in limiting biotic changes in streams and wetlands after BMP implementation have been published in scientific journals, although some work exists in reports or is unpublished. We review these works, and compile conclusions about BMP efficacy for biota from this body of research.     

Characterization of air emissions and residual ash from open burning of electronic wastes during simulated rudimentary recycling operations

Air emissions and residual ash samples were collected and analyzed during experiments of open, uncontrolled combustion of electronic waste (e-waste), simulating practices associated with rudimentary e-waste recycling operations. Circuit boards and insulated wires were handled separately to simulate processes associated with metal recovery. The average emissions of polychlorinated dibenzodioxins and dibenzofurans (PCDD/PCDFs) were 92 ng toxic equivalency (TEQ)/kg [n = 2, relative standard deviation (RSD) = 98%] and 11 900 ng TEQ/kg (n = 3, RSD = 50%) of the initial mass of the circuit boards and insulated wire, respectively. The value for the insulated wire is about 100 times higher than that for backyard barrel burning of domestic waste. The emission concentrations of polybrominated dibenzodioxins and dibenzofurans (PBDD/PBDFs) from the combustion of circuit boards were 100 times higher than for their polychlorinated counterparts. Particulate matter (PM) sampling of the fly ash emissions indicated PM emission factors of approximately 15 and 17 g/kg of the initial mass for the circuit boards and insulated wire, respectively. Fly ash samples from both types of e-waste contained considerable amounts of several metallic elements and halogens; lead concentrations were more than 200 times the United States regulatory limits for municipal waste combustors and 20 times those for secondary lead smelters. Leaching tests of the residual bottom ash showed that lead concentrations exceeded U.S. Environmental Protection Agency landfill limits, designating this ash as a hazardous waste.     

Does Soil Acidification Affect Spruce Needle Chemical Composition and Tree Growth?

In 1994, a large survey of soil chemistry was undertaken in thecounty of Värmland in central Sweden (Lundström et al., 1998).The southern part of the county was affected by soilacidification whereas there were no such indications in thenorthern part. To investigate the influence of soil chemistryon the trees at the specific sites, the survey was continued byan analysis of needle chemistry (Norway spruce) which wasundertaken at 150 of the 180 sites, and of tree growth at 65 ofthe 180 sites. Growth was expressed as a ratio between expectedgrowth, estimated with a national, empirical growth model, andthe growth observed in the field. In statistical analyses,using rank correlation, PCA and PLS, there were only weakindications of an influence of soil chemistry on needlechemistry and on tree growth. A moderate correlation betweennitrogen and sulphur in needles was found, which wasinterpreted as an effect of deposition and of processes in thetree canopy. No obvious regional pattern of the growth ratiowas found, in contrast to the clear pattern of soilacidification. The statistical analysis could not with anycertainty point out any of the soil chemistry variables asespecially important for the tree growth ratio.     

Solubility and Potential Mobility of Heavy Metals in Two Contaminated Urban Soils from Stockholm,Sweden

The solubility and potential mobility of heavy metals (Cd, Cu,Hg, Pb and Zn) in two urban soils were studied by sequential andleaching extractions (rainwater). Compared to rural (arable) soils on similar parent material, the urban soils were highlycontaminated with Hg and Pb and to a lesser extent also with Cd,Cu and Zn. Metal concentrations in rainwater leachates were related to sequential extractions and metal levels reported fromStockholm groundwater. Cadmium and Zn in the soils were mainly recovered in easily extractable fractions, whereas Cu and Pb were complex bound. Concentrations of Pb in the residual fractionwere between two- and eightfold those in arable soils, indicatingthat the sequential extraction scheme did not reflect the solidphases affected by anthropogenic inputs. Cadmium and Zn conc. inthe rainwater leachates were within the range detected in Stockholm groundwater, while Cu and Pb conc. were higher, whichsuggests that Cu and Pb released from the surface soil were immobilised in deeper soil layers. In a soil highly contaminatedwith Hg, the Hg conc. in the leachate was above the median concentration, but still 50 times lower than the max concentration found in groundwater, indicating the possibilityof other sources. In conclusion, it proved difficult to quantitatively predict the mobility of metals in soils by sequential extractions.     

High Immobilization of NH4+ in Danish Heath Soil Related to Succession,Soil and Nutrients: Implications for Critical Loads of N

During recent decades heathlands havechanged into grasslands in regions with high atmosphericnitrogen deposition. In regions with intermediatedeposition level (e.g., Denmark) changes have been lesspronounced which may be due to delay or decrease inresponse of the ecosystem. The mor layer (O horizon) mayplay an important role for this delay due to high sinkstrength for N. In this study, the capacity for netNH₄ ⁺ immobilization and mineralization wasstudied during short- and long-term incubations (2–36 days)of mor samples from Danish dry inland heaths. High short-term capacity for net NH₄ ⁺ immobilization wasfound to be a general characteristic of Danish heath morlayers both under heather (Calluna vulgaris) andcrowberry (Empetrum nigrum ssp nigrum), the latterdominating late stages in heathland succession. The netNH₄ ⁺ immobilization was higher under youngcompared to old or dead vegetation, and higher on lessnutrient poor soils than on extremely nutrient poor soils.The addition of N, P and C stimulated CO₂ productionand net NH₄ ⁺ immobilization, but not net Nmineralization. The immobilization of ¹⁵NH₄ ⁺caused release of dissolved organic N, increased N anddecreased C/N ratio in the microbial biomass, and indicatedgrowth of microorganisms with other metabolic abilitiesthan the indigenous population. No evidence was obtained ofstabilization of immobilized ¹⁵NH₄ ⁺ intosoil organic matter during the experiment. On background ofthe results and current knowledge it was concluded that therecognition of the high capacity for net NH₄ ⁺immobilization in mor layers does not allow for a raiseof critical loads for N for northern dry inland heaths.     

Biodegradation of Injection Molded Starch-Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) Blends in a Natural Compost Environment

Injection molded specimens were prepared by blending poly (hydroxybutyrate-co-valerate) (PHBV) with cornstarch. Blended formulations incorporated 30% or 50% starch in the presence or absence of poly-(ethylene oxide) (PEO), which enhances the adherence of starch granules to PHBV. These formulations were evaluated for their biodegradability in natural compost by measuring changes in physical and chemical properties over a period of 125 days. The degradation of plastic material, as evidenced by weight loss and deterioration in tensile properties, correlated with the amount of starch present in the blends (neat PHBV < 30% starch < 50% starch). Incorporation of PEO into starch-PHBV blends had little or no effect on the rate of weight loss. Starch in blends degraded faster than PHBV and it accelerated PHBV degradation. Also, PHBV did not retard starch degradation. After 125 days of exposure to compost, neat PHBV lost 7% of its weight (0.056% weight loss/day), while the PHBV component of a 50% starch blend lost 41% of its weight (0.328% weight loss/day). PHB and PHV moieties within the copolymer degraded at similar rates, regardless of the presence of starch, as determined by ¹H-NMR spectroscopy. GPC analyses revealed that, while the number average molecular weight (Mn) of PHBV in all exposed samples decreased, there was no significant difference in this decrease between neat PHBV as opposed to PHBV blended with starch. SEM showed homogeneously distributed starch granules embedded in a PHBV matrix, typical of a filler material. Starch granules were rapidly depleted during exposure to compost, increasing the surface area of the PHBV matrix.