大孔树脂NKA-II对双酚A的吸附性能

研究了大孔树脂NKA-II对双酚A（BPA）的吸附性能,考察了吸附过程的动力学、热力学及树脂的再生性能。BPA溶液呈弱酸性,不需调节pH可直接进行吸附。BPA在大孔树脂NKA-II上的吸附过程可用准二级动力学方程很好地描述。树脂对BPA的吸附是吸热反应,符合Freundlich等温吸附方程,吸附过程属于可自发进行的物理吸附。BPA的吸附过程中同时存在着溶剂的解吸。大孔树脂NKA-II具有良好的重复使用性能,新树脂的平衡吸附量为10.44 mg/g,再生20次后平衡吸附量仍为10.43 mg/g。     

磁性离子印迹聚合物的制备及其对水中Pb(Ⅱ)的吸附

以铅离子为模板离子、乙二醇二甲基丙烯酸酯和偶氮二异丁腈为交联剂和引发剂、稀盐酸为洗脱剂,采用微波辅助反相乳液悬浮聚合法,制备了磁性离子印迹聚合物(MIIP),通过SEM、FTIR、XRD和BET技术对其进行了表征,并将其用于水中Pb(Ⅱ)的吸附.在初始质量浓度60 mg/L、溶液pH 6、吸附温度303 K、吸附时间6...     

分子印迹技术在环境科学领域中的应用

分子印迹技术（MIT）是一门新兴的边缘科学技术,它的产生与发展为环境科学打开了又一视角。介绍了MIT的产生与发展及基本原理,综述了MIT在环境科学领域中的应用,主要包括MIT在固相萃取、膜分离、色谱分析、传感器及分子印迹聚合物作为催化剂在环境修复中的应用。     

聚丙烯酰-6-氨基吡啶的制备及其对重金属离子的吸附

以2,6-二氨基吡啶为原料,合成了功能单体2-丙烯酰-6-氨基吡啶,并将其与乙二醇二甲基丙烯酸酯共聚合成了聚合物吸附剂聚丙烯酰-6-氨基吡啶。考察了聚合物吸附剂对重金属离子的吸附分离性能。实验结果表明:在混合液中Cu2+,Zn2+,Cd2+,Ni2+的初始质量浓度均为10 mg/L、聚合物吸附剂加入量为5 g/L、溶液pH=7、吸附时间为10 min的条件下,聚合物吸附剂对各离子的吸附率均大于90%;采用浓度为0.5 mol/L的HCl溶液对吸附后的聚合物吸附剂进行洗脱,4种重金属离子的洗脱率均可达97%以上;该吸附剂具有很好的稳定性,重复使用11次后其对4种重金属离子的饱和吸附量均未有明显的下降。     

可见光下氮掺杂罗丹明B分子印迹TiO_2的选择性光催化性能

采用溶胶-凝胶法和分子印迹技术,以尿素为氮源、罗丹明B为模板分子制备了氮掺杂罗丹明B分子印迹TiO_2粉末(N-TiO_2-RhB),并对样品进行了XRD、UV-Vis DRS和BET表征。表征结果显示:氮掺杂和分子印迹一定程度改善了样品的孔隙结构和孔径分布,N-TiO_2-RhB的比表面积和孔体积分别为TiO_2的1.9倍和1.5倍;氮掺杂使TiO_2的光吸收带边发生红移,而分子印迹不能改变催化剂的光吸收带边。N-TiO_2-RhB具有最佳的可见光活性和选择性,对罗丹明B的降解率高达92.7%。对罗丹明B、罗丹明6G、甲基紫和甲基绿的降解过程均符合一级反应动力学方程。     

聚丙烯酰-6-氨基吡啶的制备及其对重金属离子的吸附

以2,6-二氨基吡啶为原料,合成了功能单体2-丙烯酰-6-氨基吡啶,并将其与乙二醇二甲基丙烯酸酯共聚合成了聚合物吸附剂聚丙烯酰-6-氨基吡啶。考察了聚合物吸附剂对重金属离子的吸附分离性能。实验结果表明：在混合液中Cu²⁺,Zn²⁺,Cd²⁺,Ni²⁺的初始质量浓度均为10 mg/L、聚合物吸附剂加入量为5 g/L、溶液pH=7、吸附时间为10 min的条件下,聚合物吸附剂对各离子的吸附率均大于90%;采用浓度为0.5 mol/L的HCl溶液对吸附后的聚合物吸附剂进行洗脱,4种重金属离子的洗脱率均可达97%以上;该吸附剂具有很好的稳定性,重复使用11次后其对4种重金属离子的饱和吸附量均未有明显的下降。     

β-环糊精聚合物微球吸附Pb~(2+)的动力学研究

以β-环糊精(3-CD)为原料、环氧氯丙烷(ECH)为交联剂,制得β-环糊精聚合物(β-CDP)微球。研究了β-CDP微球对Pb~(2+)的吸附特性和动力学。实验结果表明,β-CDP微球对Pb~(2+)的吸附既符合一级动力学方程,也符合二级动力学方程。β-CDP微球对Pb~(2+)的Langmuir吸附等温线的线性拟合方程为ρ_e/Q_m=0.049 5ρ_0+0.030 3,相关系数为0.993 7;β-CDP微球对Pb~(2+)的Freundlich吸附等温线的线性拟合方程为lgQ_e=0.145 4 lgρ_e+0.970 1,相关系数为0.992 9。     

木质素基聚合物的制备及亚甲基蓝的吸附

以木质素磺酸钠为原料单体、环氧氯丙烷为交联剂,采用反相乳液聚合法制备了木质素磺酸钠交联聚合物(SLCP),并将其用于水中有机染料的吸附。表征结果显示:SLCP基本保留了木质素磺酸钠的骨架和官能团,具有良好的热稳定性。实验结果表明:SLCP对亚甲基蓝(MB)有较好的吸附选择性,在加入量为0.5 g/L时就有较高的吸附效率;在溶液p H2~6范围内吸附量随溶液p H增大而迅速提高,溶液p H6后吸附量趋于稳定;最佳吸附温度为35℃;在SLCP加入量0.5 g/L、溶液p H 6.5、吸附温度25℃、初始MB质量浓度100.5 mg/L的条件下,吸附150 min基本可达平衡,吸附平衡时的吸附量和MB去除率分别为191.2 mg/g和95.1%;SLCP对MB的吸附符合Langmuir等温吸附模型,吸附动力学符合Lagergren拟二级动力学方程。     

纳米α-MnO2催化臭氧氧化降解水中双酚A

采用水热法制备了纳米α-MnO₂催化剂,并通过XRD和SEM技术对催化剂的成分和形貌进行了表征。采用纳米α-MnO₂催化剂催化臭氧氧化降解水中的双酚A（BPA）,考察了初始溶液pH、催化剂加入量和反应温度对BPA去除率的影响。实验结果表明,纳米α-MnO₂催化剂催化臭氧氧化降解BPA的最佳工艺条件为：催化剂加入量100 mg/L,初始溶液pH 8.5,反应温度18 ℃。在此最佳条件下处理质量浓度为10 μg/mL的BPA溶液120 min,BPA去除率为96.4%。回收洗涤后第二次使用的催化剂的BPA去除率为80.5%,第三次使用的催化剂的BPA去除率为74.1%,催化剂的活性随重复使用次数的增加而缓慢降低,活性较稳定。     

聚乙烯亚胺接枝壳聚糖基六价铬印迹衍生物的制备及其选择吸附性能

以壳聚糖(CTS)微球为基材,通过定向接枝将多胺高分子树枝状聚乙烯亚胺(PEI)修饰于CTS结构,并通过离子印迹改性方法制得PEI接枝 CTS基Cr (Ⅵ)印迹衍生物(I-CTS-PEI)。优化了制备工艺条件：在第一步Schiff 碱合成中甲苯为最优溶剂;第二步戊二醛复合溶液预反应最佳条件为V_戊二醛∶m _PEI=1∶1(L/g),反应时间30 min,反应温度50 ℃;在Cr (Ⅵ)印迹改性过程中,交联剂环氧氯丙烷最佳用量为8 mL。表征结果显示,Cr (Ⅵ)是通过静电引力吸附在I-CTS-PEI 表面。当I-CTS-PEI 交联度为84%时,Cr (Ⅵ)选择吸附性最大。     

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.     

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.     

Effects of Nitrogen Deposition on Bryophyte Species Composition of Calcareous Grasslands

Regular additions of NH₄NO₃ (35–140 kg N ha⁻¹ yr⁻¹) and (NH₄)₂SO₄ (140 kg N ha⁻¹ yr⁻¹) to a calcareous grassland in northern England over a period of 12 years have resulted in a decline in the frequency of the indigenous bryophyte species and the establishment of non-indigenous calcifuge species, with implications for the structure and composition of this calcareous bryophyte community. The lowest NH₄NO₃ additions of 35 kg N ha⁻¹ yr⁻¹ produced significant declines in frequency of Hypnum cupressiforme, Campylium chrysophyllum, and Calliergon cuspidatum. Significant reductions in frequency at higher NH₄NO₃ application rates were recorded for Pseudoscleropodium purum, Ctenidum molluscum, and Dicranum scoparium. The highest NH₄NO₃ and (NH₄)₂SO₄ additions provided conditions conducive for the establishment of two typical calcifuges – Polytrichum spp. and Campylopus introflexus, respectively. Substrate-surface pH measurements showed a dose-related reduction in pH with increasing NH₄NO₃ deposition rates of 1.6 pH units between the control and highest deposition rate, and a further significant fall in pH, of >1 pH unit, between the NH₄NO₃ and (NH₄)₂SO₄ treatments. These results suggest that indigenous bryophyte composition may be at risk from nitrogen deposition rates of 35 kg N ha⁻¹ yr⁻¹ or less. These effects are of particular concern for rare or endangered species of low frequency.