甲苯对铁屑降解三氯乙烯的影响

为了探讨甲苯仔任时铁屑降解三氯乙烯（TCE）的有效性及影响因素,考察了铁屑粒径、铁屑预处理方法及甲苯初始质量浓度对TCE降解效果的影响。实验结果表明：选用粒径0．35—0．83mm的铁屑较好;用0．05mol／L的盐酸清洗后的铁屑对TCE的降解效果好于未进行酸洗的铁屑对TCE的降解效果;当m（甲苯）：m（TCE）分别为0,1．2,10．3,18．6时,TCE降解的反应速率常数分别为0．0691,0．0595,0．0458,0．0361h^-1,半衰期分别为10．03,11．65,15．13,19．20h,即随着甲苯初始质量浓度的提高,TCE降解的反应速率常数变小,半衰期变长;铁屑对甲苯具有吸附作用,甲苯的初始质量浓度越高,甲苯吸附量越大。     

GC-MS在电子束辐照降解甲苯中的应用

用甲苯作为挥发性有机化合物的代表物质,建立了活性炭吸附-二硫化碳解吸气相色谱-质谱分析方法,对电子束辐照甲苯的静态实验和动态实验进行了定性、定量分析。实验结果表明：电子束辐照能有效地降解甲笨,其降解率随吸收剂量的增加而增大;同时,甲苯降解过程中也会生成部分有毒有害物质。该分析方法的检出限为0．02mg／L,工作曲线的线性范围为10～1000mg／L,相关系数为0．9998,活性炭吸附、解吸甲苯的加标回收率大于90％。     

低pH生物滤池处理甲苯废气

采用低pH生物滤池处理甲苯废气。实验结果表明,低pH生物滤池对甲苯有较好的去除效果,当甲苯废气进气流量为420L/h、进气甲苯质量浓度为200~700mg/m3时,稳定运行阶段,甲苯平均去除效率在98%以上,出气甲苯质量浓度为0~30mg/m3。低pH生物滤池中,CO2的产生量与甲苯降解量的比(物质的量比)为2.60,小于理论值3.35。经过长时间运行,低pH生物滤池内的优势微生物由刚开始接种时的以异养细菌为主演变为真菌为主,优势真菌菌株分别属于白地霉(Geotrichum candidum)、产黄青霉(Penicillium chrysogenum)和黑曲霉(As-pergillus niger)。优势异养细菌为恶臭假单胞菌(Pseudomonas putida)。     

微波-改性活性炭-Fenton试剂氧化法降解水中2,4-二氯酚

以经Fe2（SO4）3溶液浸渍改性的活性炭作催化剂、Fenton试剂作氧化剂,采用微波-改性活性炭-Fenton试剂氧化法降解水中的2,4-二氯酚。考察了改性活性炭加入量、H2O2与Fe^2＋摩尔比、Fenton试剂加入量、微波功率和2,4-二氯酚溶液初始pH对2,4-二氯酚降解效果的影响。在改性活性炭加入量1．0g／L、n（H2O2）：n（Fe^2＋）=16．7（H2O2加入量6．0mmol／L、Fe^2＋加入量0．36mmol／L）、Fenton试剂加入量为6．36mmol／L、微波功率600W、微波辐射时间10min、2,4-二氯酚溶液初始pH为6．0的条件下,2,4-二氯酚降解率和TOC去除率分别可达98．7％和84．0％。     

纳米氧化锌的制备及其对对硝基氯苯的降解

采用蒸发氧化法制备纳米ZnO。当炉温为1100℃、空气流量为0．6m^3／h、锌粒加入量为5g时,得到高纯度类四锥体和柱形纳米ZnO。以该ZnO为光催化剂,对对硝基氯苯进行光催化氧化,考察了ZnO的加入量、对硝基氯苯的初始浓度、溶液pH等对对硝基氯苯降解率的影响。在ZnO质量浓度为0．5g／L、对硝基氯苯质量浓度为30mg／L、pH为7、光照时间为100min的条件下,对硝基氯苯降解率为98％。     

甲苯二胺对厌氧微生物活性的影响

以相对产甲烷活性(RA)和COD去除率为指标,考察不同浓度甲苯二胺对厌氧污泥微生物活性的影响。实验结果表明:甲苯二胺质量浓度为0~150 mg/L时,RA接近100%甚至高于100%,COD去除率为91%~93%,与对照组无差别,对厌氧微生物几乎没有抑制作用;当甲苯二胺质量浓度为200~400 mg/L时,RA为75%~95%,COD去除率与对照组相比下降了2~6个百分点,属于轻度抑制;当甲苯二胺质量浓度高于400 mg/L时,RA在70%以下,COD去除率降至85%以下,属于中度抑制;且随着甲苯二胺质量浓度增大,RA减小、COD去除率减小,抑制作用增强。因此,为了防止甲苯二胺对厌氧污泥微生物活性的抑制,甲苯二胺质量浓度应控制在0~150 mg/L。     

膜法处理难降解石化废水的预处理工艺研究

采用混凝法分别以聚合氯化铁（PFC）、聚合氯化铝（PAC）和聚合硫酸铁（PFS）为混凝剂处理天津某石油化工厂二级氧化处理工艺出水,PFC对废水COD的去除效果最好,在PFC加入量为120mg／L时,废水的COD去除率最高,为22．35％。经正交实验确定了Fenton试剂氧化法处理废水的最佳实验条件为：Fe^2＋加入量290mg／L、H2O2加入量100mg／L、pH=6、反应时间30min,此时COD去除率为20．45％。活性炭吸附法对废水的处理效果随活性炭加入量增加而改善,活性炭的最佳加入量为2000mg／L,此时废水的COD去除率最高,为87．78％。     

活性碳纤维-臭氧氧化降解水中聚氧乙烯脂肪醇醚的方法

该发明涉及水处理领域中活性碳纤维-臭氧氧化降解水中聚氧乙烯脂肪醇醚类的方法。技术方案是对预处理后的原水按200～800mg／L加入量添加絮凝剂,将废水中的固体悬浮物絮凝、沉降、分离,送入循环的反应器;反应器底部设置有与臭氧发生器连接的布气板,布气板上部设置单层或多层经过改性的活性碳纤维;反应器内活性碳纤维加入量为10—50g／L,臭氧气体质量浓度为3～6mg／L,流量为0．12～0．50m^3／h,处理时间为10～90min,反应温度控制在22—45℃,调节废水的pH为碱性。     

Cu2+-Mn2+-H2O2体系催化氧化降解罗丹明B

研究了Cu2＋-Mn2＋-H2O2体系催化氧化降解染料罗丹明B的效果。实验结果表明,Cu2＋-Mn2＋-H2O2体系的罗丹明B降解率比H2O2体系、Mn2＋-H2O2体系和Cu2＋-H2O2体系有显著提高,反应120rain后罗丹明B降解率接近100％。对于Cu2＋-Mn2＋-H2O2体系,最佳罗丹明B降解条件：溶液pH为5,反应温度为45℃,质量浓度为10mg／L的罗丹明B溶液体积100mL,浓度为0．01mol／L的硫酸铜溶液加入量5．0mL,浓度为0．01moVL的硫酸锰溶液加入量3．0mL,体积分数为30％的H2O2溶液加入量1．5mL。在此条件下罗丹明B降解的反应速率常数最大,为0．04228min-1,其拟合相关系数为0．99912。罗丹明B降解符合一级动力学模型。     

利用磷化渣配制复合磷化液

采用固体废物磷化渣配制成复合磷化液,并用所配制的复合磷化液对A3钢试件进行磷化处理,形成磷化膜。通过正交实验确定了配制复合磷化液的较佳配方为：磷化液基础液加入量0．2L／L、氧化锌加入量5g／L、碳酸钠加入量6g／L、硝酸加入量12．5mL／L、浓磷酸加入量2．5mL／L、硫酸铜加入量0．3g／L。复合磷化液为浅绿色透明溶液,pH为4．0,总酸度为40,游离酸度为10,磷化温度为65℃,磷化时间为300～600s。所形成的磷化膜厚度为16．0μm,单位质量为26．875g／m^2,粗糙度为1．425μm,维氏硬度为124．27kgf／mm^2。磷化膜硫酸铜点滴时间为35s,耐盐水时间为8h,耐盐雾时间为4h,其物理性质和耐蚀性能均较佳。     

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.