煤矸石的改性及其对稀土生产废水中氨氮的吸附

采用热改性、盐酸改性、硫酸改性、碱改性的方法分别制备了4种改性煤矸石吸附剂,研究了吸附工艺条件对4种改性煤矸石吸附剂对稀土生产废水中氨氮去除效果的影响以及吸附机理.实验结果表明:4种改性煤矸石吸附剂吸附氨氮的最佳工艺条件为:吸附剂加入量0.02 g/mL,振荡时间2.5 h,废水pH 7～8;4种吸附剂氨氮去除率大小顺序为:碱改性煤矸石＞硫酸改性煤矸石＞盐酸改性煤矸石＞热改性煤矸石;碱改性煤矸石的氨氮去除率最高,为59.19％;碱改性煤矸石吸附剂对含氨废水中氨氮的吸附较好地符合Langmuir方程和Freundlich方程,在一定程度上符合Temkin方程.     

用于脱除水中氨氮的 NaA-1 型离子交换剂的研究

通过对失去干燥性能的分子筛废弃物进行再生改性，开发出了一种新型的用于脱除水中氨氮的离子交换剂。研究了水中共存阳离子对氨氮去除率的影响，测定了交换容量，研究了交换时间、温度及再生方法等条件与氨氮去除率的关系，并对交换剂的性能与结构进行了关联，优化了该交换剂用于处理氨氮废水的操作条件。     

改性水热炭同时吸附溶液中Cr(Ⅵ)和Cd(Ⅱ)

以竹屑为基质制备了水热炭(HC),通过NaOH溶液和ZnCl2溶液改性分别制备了改性水热炭OHHC和ZHC,并将两种改性水热炭耦合制成复合水热炭MHC.考察了水热炭投加量和初始溶液pH对溶液中Cr(Ⅵ)和Cd(Ⅱ)去除率的影响.并通过吸附动力学和等温吸附曲线,探究吸附机理.实验结果表明:ZHC的芳香性增高,比表面积增大...     

粉煤灰的改性及其对高盐苯胺废水的处理

以盐酸和硫酸作为改性剂,对粉煤灰进行改性。通过正交实验得到最佳改性粉煤灰制备条件为：V（盐酸）∶V（硫酸）=1∶5,浸泡时间6h,活化时间6h,活化温度250℃。在初始苯胺质量浓度为200mg/L、氯化钠质量分数为15%、吸附时间为60min的条件下,采用在最佳条件下制备得到的改性粉煤灰对苯胺进行吸附,吸附量可达4.16mg/g。采用Freundlich方程可更好地对改性粉煤灰吸附苯胺的过程进行拟合。     

粉煤灰基沸石分子筛对水中氨氮的吸附

以粉煤灰为原料,采用碱熔融-水热法制备了3种沸石分子筛,运用XRD、XRF、SEM和BET等手段进行了表征,并将分子筛用于吸附溶液中的氨氮,考察了影响氨氮吸附效果的主要因素、氨氮等温吸附特征和吸附动力学特征。结果表明：分子筛B(Na_20.8Al₂₃Si₃₆O₁₁₇·7.69 H₂O)对氨氮的吸附效果最佳,在初始氨氮质量浓度100 mg/L、分子筛B加入量2 g/L、初始溶液pH 7、吸附温度25℃、转速150 r/min的条件下,吸附60 min后,氨氮吸附量和去除率分别为40.61 mg/g和90%;4种阳离子对氨氮吸附效果的影响顺序依次为K⁺>Ca²⁺>Na⁺>Mg²⁺;分子筛B对氨氮的吸附为单分子层吸附,具有化学吸附的特征;分子筛B吸附氨氮的的最佳工艺条件为初始溶液pH 7、吸附温度45℃、初始氨氮质量浓度40 mg/L,在该条件下,氨氮去除率为93%。     

超声吹脱—吸附工艺处理高浓度氨氮废水

采用超声吹脱—吸附工艺处理高浓度氨氮废水。在超声吹脱工艺的基础上,利用改性沸石对超声吹脱后的废水进行超声强化吸附处理,考察了沸石粒度、吸附时间、沸石投加量、吸附温度、吸附超声功率等因素对处理效果的影响。实验结果表明：超声吸附处理废水的优化工艺条件为沸石粒度0.198~0.245 mm、吸附时间60 min、沸石投加量4 g/L、吸附pH 7.0、吸附温度30 ℃、吸附超声功率100 W;在该条件下,超声吹脱—吸附工艺的总氨氮去除率可达77.39%,较单独超声吹脱工艺的41.98%大幅提高。     

粉煤灰及其制备沸石对高浓度氨氮的去除比较

以粉煤灰为原料,采用改进的水热合成法制备了粉煤灰沸石,并将粉煤灰和粉煤灰沸石用于高浓度氨氮的吸附去除。实验结果表明:在粉煤灰和粉煤灰沸石的投加量分别为0.10 g/m L和0.04 g/m L、反应体系p H为5~7、初始氨氮质量浓度为500 mg/L的条件下,分别吸附660 min和60 min,粉煤灰和粉煤灰沸石对氨氮的去除率分别约为20.1%和50.7%左右,粉煤灰沸石对高浓度氨氮的去除效果明显优于粉煤灰;粉煤灰和粉煤灰沸石对氨氮的吸附动力学行为符合准二级动力学方程;Langmuir和Freundlich等温吸附模型能较好地描述粉煤灰对氨氮的等温吸附过程,而粉煤灰沸石对氨氮的等温吸附过程则更适宜用线性模型和Freundlich模型描述。     

腐殖酸-海泡石复合钝化剂的制备及其对Cd污染土壤的修复

对海泡石进行热改性,以腐殖酸和海泡石为原料,制备了腐殖酸-海泡石复合钝化剂。采用BCR形态分析法研究了复合钝化剂对镉污染土壤的钝化效果。结果表明,制备复合钝化剂的最佳工艺条件为：腐殖酸与海泡石质量比2∶1,氢氧化钠质量浓度0.04 g/mL,热反应时间40 min,热反应温度80 ℃。复合钝化剂的最佳添加量为7%（w）,培养3 d后,钝化效率达46.87%,土壤pH升高至7.02,活稳比降低为0.65,土壤中镉的释放风险显著降低。复合钝化剂修复镉污染土壤时,会促使活性态镉向稳定态镉转化,使镉在土壤中的稳定性提高。     

用改性海泡石处理含磷废水

以海泡石为原料,经盐酸活化、水热活化,再加入氯化镁、氯化铁复合制得除磷剂原粉;再用聚氯乙烯将除磷剂原粉黏合成粒状除磷剂。用粒状除磷剂对废水中的磷（PO4^3-）进行吸附、洗脱,考察除磷剂的循环使用性能。实验结果表明：除磷剂对废水中磷的吸附容量可达92m g/g以上;以碳酸钠为洗脱剂,磷的洗脱率可达90%以上;除磷剂可重复使用,且性能优良。     

用海泡石处理采油废水

用海泡石吸附法处理采油废水,考察了处理时间、海泡石加入量和采油废水pH对采油废水COD去除率的影响,并通过正交实验优化了采油废水处理工艺条件。通过正交实验得到的采油废水处理最佳工艺条件为：处理时间6h,粒径为150μm的海泡石加入量200g／L,采油废水pH9。在该条件下处理采油废水,COD去除率达到91％,处理后出水的COD为34．71mg／L,小于GB8978-1996（（污水综合排放标准》中的一级标准（60mg／L）。     

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.     

Historical Weathering Based on Chemical Analyses of Two Spodosols in Southern Sweden

Chemical weathering losses were calculated for two conifer stands in relation to ongoing studies on liming effects and ash amendments on chemical status, soil solution chemistry and soil genesis. Weathering losses were based on elemental depletion trends in soil profiles since deglaciation and exposure to the weathering environment. Gradients in total geochemical composition were assumed to reflect alteration over time. Study sites were Horröd and Hasslöv in southern Sweden. Both Horröd and Hasslöv sites are located on sandy loamy Weichselian till at an altitude of 85 and 190 m a.s.l., respectively. Aliquots from volume determined samples from a number of soil levels were fused with lithium metaborate, dissolved in HNO₃, and analysed by ICP – AES. Results indicated highest cumulative weathering losses at Hasslöv. The weathering losses for the elements are in the following order:Si > Al > K > Na > Ca > MgTotal annual losses for Ca+Mg+K+Na, expressed in mmol_c m^-2 yr^-1, amounted to c. 28 and 58 at Horröd and Hasslöv, respectively. Variations between study sites could not be explained by differences in bulk density, geochemistry or mineralogy. The accumulated weathering losses since deglaciation were larger in the uppermost 15 cm than in deeper B horizons for most elements studied.