从含镍二壬基萘磺酸-煤油溶液中反萃取镍

采用简单反萃取法回收含镍二壬基萘磺酸（DNNSA）-煤油溶液中的镍。考察了反萃剂种类、反萃时间、反萃温度、油水比（负载镍的有机相与反萃剂的体积比）、反萃剂浓度等对反萃率的影响。实验结果表明,在硫酸作为反萃剂、反萃剂浓度为0.3mol/L、反萃时间为10min、反萃温度为30℃、油水比为3的工艺条件下,反萃率达81.5%。反萃取后得到的DNNSA可多次重复用于含镍废水的萃取处理,Ni²⁺萃取率基本保持不变。     

利用醋酸废水制取醋酸钙镁盐

用三辛胺萃取醋酸废水中的醋酸，加入白云石灰乳反萃、可制得环保型除冰剂醋酸钙镁盐（CMA）。研究了萃取剂组成，剂水比，萃取温度，萃取时间，搅拌速度对萃取效率的影响，确定了反萃的操作条件。试验表明：采用该法处理稀醋酸，工艺简单、醋酸利用率高。     

FeCl3蚀刻液膜电解阴极液中Ni2+的萃取回收

采用自制的SSX萃取剂对FeCl₃蚀刻液膜电解阴极液（简称废液）中的Ni²⁺进行萃取回收。考察了萃取pH、SSX萃取剂含量、萃取相比（SSX萃取剂与废液的体积比）、萃取时间、萃取次数对Ni²⁺萃取率的影响,以及反萃剂HCl溶液浓度、反萃相比（反萃剂与萃取液的体积比）、反萃时间对Ni²⁺反萃率的影响。实验结果表明： 当SSX萃取剂质量分数20%、萃取pH 2.0、萃取相比1.0、萃取时间10 min、1次萃取时,Ni²⁺萃取率可达74.56%;当反萃剂HCl溶液浓度6.0 mol/L、反萃相比1.5、反萃时间10 min时,Ni²⁺反萃率达93.10%;再生后的SSX萃取剂重复使用4次后,Ni²⁺的累积萃取率达91.00%,萃取剂中Ni²⁺的质量浓度可达14.94 g/L;反萃液经浓缩、结晶处理可制备电镀用NiCl₂产品。     

从苯酐生产废水中萃取富马酸

用三辛癸胺和三辛胺为萃取剂,在无稀释剂的条件下,对苯酐生产废水中的富马酸进行了络合萃取研究。研究结果表明,萃取剂的负荷量与相比呈递减的幂函数关系,三辛癸胺比三辛胺的络合酸度大;温度对萃取处理效果有明显影响,温度为10～40℃时,萃取剂的负荷量随着温度的升高而增加,但温度过高易造成乳化,最佳操作温度为30～40℃;用氢氧化钠溶液再生萃取剂,最佳反萃操作条件为:振荡时间60s、相比(水/油,体积比)2、温度60℃、碱液质量浓度12g/L;萃取剂9次循环萃取和再生使用过程中,萃取率稳定在71 8%±1 7%,再生效率稳定在94 3%±1 9%,9次循环后萃取剂的损失量为4%;从每吨废水中可回收富马酸4 8kg,可获益24元。     

J酸生产废液冷冻分离的研究

采用冷冻分离法处理J酸生产过程中产生的酸性废液,具有设备简单、能耗小、处理费用低的特点。该法的主要步骤:①将废液冷冻至-10——20℃,使其中的Na_2SO_4结晶析出,然后进行过滤去除;②将滤液进行换热、浓缩后,送回原生产工序循环使用。采用该法处理这种酸性废液,不但可消灭这种污染源,而且回收了资源。     

萃取法回收钛白水解废酸中的硫酸

提出了以三异辛胺作萃取剂、H2O作反萃取剂从钛白水解废酸中萃取回收硫酸的新工艺。考察了萃取剂浓度、相调节剂浓度、相比及温度对萃取和反萃取的影响，并进行了模拟试验。在以40％三异辛胺、25％仲辛醇和35％航空煤油(均为质量分数)为萃取有机相，相比为2，以H2O为反萃剂，相比为1．5的条件下，质量浓度为146．02g/L的废酸经8级萃取和6级反萃取，硫酸回收率达到91．81％，产品酸质量浓度达119．73g/L。     

国外动态

萘酚生产废水含有大量无机盐(Na_2SO_4、Na_2SO_3)和有机物(β-萘磺酸和其他)。采用电渗析法可以有效地净化该废水,并能得到氢钣化钠和硫酸。实验是在装有离子膜、铂钛阴极和阳极的三室电渗析器内进行。离子膜牌号为 MK-40和 MA-40,电流密度为0.08—0.12安/厘米~2。电解4～5小时,无机盐去除率达97—99%,有机物去除率达95—98%(按 COD 计)。净化后的废水可回用。阴极电解液硫酸(70克/升)和阳极电解液氢氧化钠(60克/     

多级冷冻法处理含油废水

采用多级冷冻法处理含油废水。实验结果表明:在初始废水中COD和ρ(NH3-N)分别为36 400 mg/L和73 mg/L的条件下,经过8级冷冻处理,COD和ρ(NH3-N)分别降至430 mg/L和2 mg/L,去除率分别可达98.82%和97.72%;在相同COD的条件下,ρ(NH3-N)较高时,COD去除率较高,由此可见无机盐离子(如NH4+)的存在有利于有机物的去除。     

DSD酸氧化缩合废水浓缩液回用试验研究

研究了DSD酸氧化缩合废水浓缩液回用到原生产过程的可行性。对DSD酸氧化缩合废水可采用萃取技术分离出其中97％的有机物，反萃产生的4－8倍的浓缩液返回到DSD酸生产中的氧化缩合单元后，可提高DNS酸的收率约7．43％，且不会明显影响产品的纯度，浓缩液8次循环磁用试验的结果表明，虽然DSD酸氧化缩合废水的COD从15000－20000mg/L提高到20000－29000mg/L，但没有显著持续增长的趋势，表明反应液中副产物的浓度得到了有效的控制。     

用液膜技术分离水溶液中的铜

研究了用二(2-乙基己基)磷酸酯(P_(204))-Span 80-煤油-H_2SO_4液膜体系从水溶液中分离铜(Ⅱ)的工艺。对乳液膜中有无液体石蜡、Span 80用量、反萃酸浓度、外液pH以及膜有机试剂的循环使用等条件进行了考察,求得了较适宜的工艺条件。对于含Cu~(2+)浓度小于500ppm的水溶液,经一次处理可达到4ppm以下,液膜分离铜的效率达96％以上。     

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.     

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.     

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.     

Transformations of nitrogen at the interface between the topsoil and an impervious clay subsoil

Much work has been done on gaseous emissions and leaching of nitrogenous compounds from whole soil profiles and also from soil surface measurements which are assumed to be mainly due to topsoil activity. In soils with an impervious clay subsoil, the boundary between the topsoil and subsoil may provide an interface for microbial activity, including N transformations. In this study, we investigated movement and transformations of two reactive N species (nitrate and urea) at the subsoil interface using a series of replicate, intact soil blocks, under two contrasting watering regimes. We measured fluxes in both liquid and gaseous phases and demonstrated that nitrate reaching the subsoil interface does not necessarily leach into water systems, but may denitrify immediately and could, therefore, add to atmospheric pollution through N₂O production. On the other hand, ammonium reaching the subsoil interface either directly, or after mineralization, appears to be more mobile than expected and has the potential to pollute watercourses.     

The Spatial and Temporal Variation of Measured Urban PM10 and PM2.5 in the Helsinki Metropolitan Area

We have studied particulate matter (PM) concentrations,PM₁₀ and PM_2.5, measured in an urban air qualitymonitoring network in the Helsinki Metropolitan Area during1997–1999. The data includes PM₁₀ concentrationsmeasured at five locations (two urban traffic, one suburbantraffic, one urban background and one regional backgroundsite) and PM_2.5 concentrations measured at twolocations (urban traffic and urban background sites). Theconcentrations of PM₁₀ show a clear diurnal variation,as well as a spatial variation within the area. Bycontrast, both the spatial and temporal variation of thePM_2.5 concentrations was moderate. We have analysedthe evolution of urban PM concentrations in terms of therelevant meteorological parameters in the course of oneselected peak pollution episode during 21–31 March, 1998.The meteorological variables considered included wind speedand direction, ambient temperature, precipitation, relativehumidity, atmospheric pressure at the ground level,atmospheric stability and mixing height. The elevated PMconcentrations during the 1998 March episode were clearlyrelated to conditions of high atmospheric pressure,relatively low ambient temperatures and low wind speeds inpredominantly stable atmospheric conditions. The resultsprovide indirect evidence indicating that the PM₁₀concentrations originate mainly from local vehiculartraffic (direct emissions and resuspension), while thePM_2.5 concentrations are mostly of regionally andlong-range transported origin.     

Methane generation from corncobs treated with xylanolytic consortia

Consortia were developed for the treatment of corncobs for use as a feedstock in a biogas fermentor. The treatment of corncobs with xylanolytic consortia enhanced the production of methane and biogas. All five consortia developed produced the maximum biogas and methane at a 6% loading rate and 20 days hydraulic retention time (HRT). The maximum biogas yield of 0.59m³/kg volatile solids (VS) with a methane content of 62% was produced with the KK-10 consortium. This was apparently due to a maximum hemicellulose degradation of 88%.     

Recovery of Acidified Lakes: Lessons From Sudbury, Ontario, Canada

Over 7,000 lakes around Sudbury, Ontario, Canada were acidified by S deposition associated with emissions from the Sudbury metal smelters and more distant S sources. Air pollution controls have led to widespread changes in damaged Sudbury lakes, including increased pH and decreased concentrations of SO₄, metals and base cations. While chemical improvements have often been substantial, many lakes are still acidified, although water quality recovery is continuing. Biological recovery has been observed in some lakes among various groups of organisms including fish, zooplankton, phytoplankton and zoobenthos. Generally, however, biological recovery is still at an early stage. Lakes around Sudbury are also showing that the recovery of acid-damaged lakes is closely linked to the effects of other major environmental stressors such as climate change, base cation depletion and UV-B irradiance. Future studies of the recovery of acid-damaged lakes around Sudbury, and in other regions, will need to consider the interactions of these and other stressors.     

Preparation and Biodegradation of Starch/Polycaprolactone Films

Starch granules were modified with trisodium trimetaphosphate (TSTP) and characterized by P³¹-NMR, FTIR and DSC. Seventy-micron films were prepared from modified starch and polycaprolactone blends by solvent casting technique. Three different types of films—PCL (100% polycaprolactone), MOD-ST/PCL (50% modified starch and 50% polycaprolactone blend) and NONMOD-ST/PCL (50% nonmodified starch and 50% polycaprolactone blends)—were prepared, and their thermal, mechanical, and morphologic properties were investigated to show the increased performance of PCL with the addition of starch and also the effect of modification. It was observed that with the addition of starch the Young's modulus of polycaprolactone was increased and became less ductile, whereas tensile strength and elongation at break values decreased. Biodegradation of these films was inspected under different aerobic environments with the presence of Pseudomonas putida, activated sludge, and compost. It was observed that whereas P. putida had almost no effect on degradation during 90 days, with the presence of activated sludge, considerable deformation of films was observed even in the first 7 days of degradation. In a compost environment, degradation was even faster, and all polymer films were broken into pieces within first 7 days of degradation and no film remained after 15 days.