含Cu-Zn废催化剂的综合利用

含 Cu- Zn催化剂 ,如 Cu/Zn/Al催化剂 ,主要用于合成氨工业、制氢工业的低温变换反应 ,合成甲醇和催化加氢反应。用于合成甲醇时 ,催化剂中 Cu O的质量分数为 45 %～ 65 % ,Zn O的质量分数为 2 5 %～ 45 % ;用于低温变换反应时 ,Cu O的质量分数为30 %～ 40 % ,Zn O的质量分数为 40 %～ 5 0 %。由于在使用过程中都是使用还原状态的铜 ,因此造成催化剂失活的原因具有一些共同的特点 ,如硫中毒、卤素中毒、热老化等。这使得此类催化剂寿命短 ,再生困难 ,因而产生大量的失活催化剂。如果能较好地处理和利用这些废催化剂 ,可充分利用资源 ,…     

甘氨酸母液脱色废活性炭的微波-Fenton试剂氧化法再生

采用微波-Fenton试剂氧化法对甘氨酸母液脱色过程中产生的废活性炭进行再生,考察了废活性炭再生率的影响因素,并用SEM对再生活性炭进行了表征.实验结果表明,在Fenton试剂中n(H2O2)∶n(Fe2+)为24∶1、H2O2的浓度为25 mmol/L、溶液pH为3、反应温度为55℃、反应时间为18 min、微波功率为600 W时,废活性炭的再生率可达到75.80％.     

植物法改性类Fenton反应催化剂降解甲基橙

采用银杏叶和桑叶提取液制备了改性类Fenton反应催化剂并进行了表征分析,研究了溶液初始p H、反应温度、催化剂加入量、甲基橙初始质量浓度等因素对甲基橙降解率的影响,同时考察了催化剂的重复使用效果。表征结果表明:制备出的催化剂为Fe_2O_3和Fe OOH的混合物;桑叶改性催化剂的粒径分布较银杏叶改性催化剂均匀,粒径较小,比表面积较大。实验结果表明:在初始p H为6.23、反应温度60℃、催化剂用量1 g/L、甲基橙初始质量浓度100 mg/L的条件下,银杏叶改性催化剂的甲基橙降解率为99.40%,桑叶改性催化剂的甲基橙降解率为99.96%;碱性条件下,甲基橙降解率仍接近100%,扩宽了反应的p H适用范围,为碱性条件下处理偶氮染料提供了新思路;催化剂重复使用6次之后,甲基橙降解率仍可达到99%。根据反应前后溶液的紫外-可见吸收光谱,初步探讨了降解机理。     

IC反应器处理MTO废水的中试研究

中试研究了内循环(IC)反应器处理甲醇制烯烃(MTO)废水的启动和运行过程,同时考察了颗粒污泥的性状及沼气产量的变化情况。试验过程运行稳定,系统抗冲击性强。以絮状污泥为接种污泥,经过131 d的启动和运行,IC反应器的COD去除负荷可达10 kg/(m~3·d)以上,COD去除率可达90%以上。IC反应器中的成熟颗粒污泥形状规则、密实、粒径大、沉降速率快。IC反应器的沼气产量符合理论预期。     

类过氧化物酶Fe-TAML催化H_2O_2脱除烟气中的单质汞

采用有机合成法制备了类过氧化物酶(Fe-TAML)催化剂。利用制备的Fe-TAML催化H_2O_2脱除烟气中的Hg~0,考察了影响Hg~0去除率的多种因素。实验结果表明:在Fe-TAML催化剂用量为0.08 g/L、H_2O_2浓度为0.035mol/L、溶液pH为9、反应温度为40℃、烟气中Hg~0质量浓度为101.00μg/m3的条件下,反应30 min的平均Hg~0去除率可达71.50%。以甲醇作为HO·的淬灭剂开展了淬灭实验,结合产物分析,推测了Hg~0的去除机理。     

Bi/Fe_3O_4催化NaBH_4还原水中对硝基苯酚

以磁性Fe_3O_4为载体负载Bi(NO_3)_3,再用NaBH_4还原Bi~(3+)制备了Bi/Fe_3O_4催化剂。采用XRD和紫外-可见光谱对催化剂进行表征。考察了Bi负载量、NaBH_4加入量和Bi/Fe_3O_4加入量对Bi/Fe_3O_4催化NaBH_4还原对硝基苯酚(4-NP)效果的影响。表征结果显示:当催化剂中Bi含量较少时,Bi分散良好;当Bi含量较多时,会形成纳米颗粒。实验结果表明:当反应温度为25℃,初始4-NP浓度为4.0 mmol/L时,在Bi负载量为5%(w)、Bi/Fe_3O_4催化剂加入量为500 mg/L,NaBH_4加入量为6.0 g/L的条件下,反应速率常数为0.581 min~(-1),4-NP的去除率为99.7%;Bi/Fe_3O_4催化剂稳定性好,重复使用15次后,活性基本不变。     

化肥废催化剂的回收利用（下）

(续1993年第3期)6 废铜锌催化剂的回收氨厂所用的低温变换、合成甲醇催化剂以及国外新近开发应用的部分高温变换催化剂均属铜锌系催化剂。低温变换催化剂在氨厂用量较大,如在中原化肥厂低变炉中共计装B_(206)型低温变换催化剂90m~3,重量为141.68t,因而一旦换下,废催化剂量是很大的。现在生产甲醇的厂家很多,且多为合成氨联产甲醇,这些小型联产厂,未能解决原料气中微量硫对铜锌系催化剂的中毒问题,催化剂寿命很短,有的厂甚至只能用2-4个月,频繁换出的废催化剂量很大,如能回收废催化剂,势必能降低     

废油脂制备生物柴油的清洁生产工艺

在固定床反应器中，采用自制固体催化剂催化废油脂与甲醇发生酯交换反应制备生物柴油。最佳反应条件为：甲醇与废油脂摩尔比6，液态空速2h，反应温度290℃。废油脂预处理简单，酸值为180mg／g时，生物柴油的产率可达85％。所制备的，仨物柴油各项物性数据均符合我国轻柴油的标准，也完全达到德国和美国生物柴油的指标要求。该生物柴油制备方法属清洁生产工艺，无废水产生。     

吸附—光催化氧化法处理模拟亚甲基蓝废水

以粉煤灰基沸石为载体制备TiO2/沸石光催化剂,采用SEM和XRD对产物进行表征,并考察其对模似废水中亚甲基蓝(MB)的光催化降解活性及再生后的催化性能.实验结果表明:光催化剂中的TiO2主要为锐钛矿晶型;MB降解过程遵循—级Langmuir-Hinshelwood动力学方程;当光照时间为3h、MB质量浓度为10 mg/L、废水pH为7、TiO2/沸石加入量为1.5 g/L时,MB废水的脱色率可达96.46％;经200 W超声波、450℃热再生处理40 min后,再生催化剂对废水的脱色率为73.04％;再生催化剂重复使用8次后,废水脱色率仍可达43.27％.     

对废聚乙烯热解过程的研究

<正>Fuel,2014,133(10):276废高密度聚乙烯(HDPE)可转化为大量的气体(转化率大于90%)。感应加热被引入作为热解废HDPE的一种高效节能方法。研究人员研究了加氢裂化对烷烃-烯烃比的影响,并评估了连续操作模式下催化剂的失活和再生性能。研究人员深入研究了废聚乙烯瓶的热催化裂解,以确定在连续模式下操作该工艺的可能性。以强大的催化性能和精确的选择性而著称的两种类型的沸石催化剂(HUSY和HBeta),被用来研究在     

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.     

Programs assessing implementation and effectiveness of state forest practice rules and BMPs in the West

The major forest nonpoint source control programs in the West are largely regulatory, either under forest practices acts (California, Idaho, New Mexico, Nevada, Oregon, and Washington) or a streamside management act (Montana). These programs and the specific rules they enforce continue to undergo intensive scrutiny. Still, the questions are the same for these regulatory programs as for states that base nonpoint source control on voluntary BMPs (Arizona, Colorado, Utah, Wyoming). Are the rules or BMPs being applied, and are they effective in reducing nonpoint source pollution to levels that protect beneficial uses of water? The level of debate about forestry in the West has resulted in detailed monitoring and research to answer these questions. In the past, state agencies have assumed levels of BMP compliance based on the percent of operations without enforcement actions. These estimates are being replaced by statistically valid and reproducible monitoring of forest practices rules and BMP compliance levels. BMP effectiveness is being assessed using both qualitative and quantitative methods. This can involve field assessments, process-based research, and control watershed studies. Some trend monitoring is also beginning. With the regional implementation rate for forestry BMPs at about 94% and rising, it is likely that effectiveness testing will continue to be a priority and consume the majority of assessment resources for this region.     

Hysteresis in Reversal of Central European Mountain Lakes from Atmospheric Acidification

Extremely high emissions of S and N compounds in Central Europe (both 280 mmol m^-2 yr^-1) declined by 70and 35%, respectively, during the last decade. Decreaseddeposition rates of SO₄ ^-2, NO₃ ^-, and NH₄ ⁺ in the region paralleled emission declines. The reduction in atmospheric inputs of S and N to mountain ecosystemshas resulted in a pronounced reversal of acidification in the Tatra Mountains and Bohemian Forest lakes. Between the 1987–1990and 1997–1999 periods, concentrations of SO₄ ^-2 and NO₃ ^- decreased (average ± standard deviation) by 22±7 and 12±7 mol L^-1, respectively, in theTatra Mountains, and by 19±7 and 15±10 mol L^-1, respectively, in the Bohemian Forest. Their decrease was compensated in part (1) by a decrease in Ca²⁺ + Mg²⁺ (17±7 mol L^-1) and H⁺ (4±6 mol L^-1), and an increase in HCO₃ ^-(10±10 mol L^-1) in the Tatra Mountains lakes, and (2) by a decrease in Al (7±4 mol L^-1), Ca²⁺ + Mg²⁺ (9±6 mol L^-1), and H⁺ (6±5 mol L^-1), in Bohemian Forest lakes. Despite the rapid decline in lake water concentrations of SO₄ ^-2 and NO₃ ^- in response to reduced S and N emissions, their present concentrations in some lakes are higher than predictionsbased on observed concentrations at comparable emission rates during development of acidification. This hysteresis in chemical reversal from acidification has delayed biological recovery of the lakes. The only unequivocal sign of biological recovery hasbeen observed in erné Lake (Bohemian Forest) where a cladoceran species Ceriodaphnia quadrangular has recentlyreached its pre-acidification abundance.     

Reconstruction of Long-Term Changes in Lake water Chemistry,Zooplankton and Benthos of a Small,Acidified High-Mountain Lake: Magic Modelling and Palaeolimnogical Analysis

Starolesnianske pleso is a small and shallow acid lake in the High Tatra Mountains, situated at 2000 m above sea level, on granitic bedrock, with sparse and thin soil cover. When detailed measurements began in the 1980s Starolesnianske pleso had pH below 5 and only one species of cladoceran zooplankton, the ubiquitous Chydorus sphaericusPalaeolimnological investigations show changes in cladoceran zooplankton and chironomid zoobenthic assemblages since about 1920 and a major change in 1970–1980. The dynamic acidification model MAGIC was used to reconstruct changes in water chemistry over the past 150 years. The results from MAGIC agree well with the sediment record; pH levels gradually decreased from 6.5 in the mid-1800s to about 5.6 in 1920 (first response in biota) to below 5.0 by 1970, and concentrations of inorganic aluminium rose dramatically beginning about 1960. In the 1990s the lake water chemistry showed clear signs of reversal in acidification brought about by a major decline in S deposition.     

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.     

Heavy Metals Removal by Biosorption and Flotation

The removal of a mixture of heavy (toxic) metal cations (copper, nickeland zinc) from liquid effluents was investigated in this study at pilotscale, using counter-current contact mode. The innovative processinvolved the abstraction of metal ions onto fungal biosorbents, followedby the application of flotation for the subsequent solid/liquid separationof biomass particles. The ability of microorganisms to remove metal ionsfrom aqueous solutions is a well-known phenomenon. Nevertheless,engineering considerations are very important in decisions, concerningthe commercial future of biosorption and practical solutions are neededfor certain problems, such as the efficient post-separation ofmetal-loaded biomass. The two processes (flotation and biosorption) caneffectively operate in combination, in what it was termed biosorptiveflotation process. The sorbents may be recycled, after appropriate elutionof metals, as well as the treated (clean) water.     

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.     

Selection of Autochthonous Plant Species from SE Spain for Soil Lead Phytoremediation Purposes

Mining activity in SE of Spain, in the west Mediterranean coast, originated more than two millenniums ago. It has generated huge areas affected by heavy metals contamination, especially of lead, which is possibly one of the most important. Investigations related to the selection of autochthonous plant taxa from a typical Spanish Mediterranean area, useful for phytoextraction and phytostabilization purposes in these polluted areas are shown. Under these edaphoclimatic conditions 12 interesting species were considered, from them six taxa were chosen for further studies. Some plant species have been proposed either for phytoextraction or phytostabilization purposes. Recommendations for further research have been discussed.     

Concentrations and Pools of Heavy Metals in Urban Soils in Stockholm,Sweden

The concentrations of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb andZn) and arsenic (As) were surveyed and the metal pools estimatedin soils in Stockholm Municipality. The sampling sites were distributed all over the entire municipality with a higher sampling density in the city centre. Soils were sampled to a maximum depth of 25 to 60 cm. Soil texture, total-C content, electrical conductivity and pH were analysed. Heavy metal concentrations were determined after wet digestion with boiling7 M HNO₃.The results showed a wide range in heavy metal concentrations, as well as in other soil properties. The city centre soils constituted a rather homogeneous group whereas outside this areano geographical zones could be distinguished. These soils were grouped based on present land use, i.e. undisturbed soils, public parks, wasteland (mainly former industrial areas), and roadside soils. The city centre and wasteland soils generally hadenhanced heavy metal concentrations to at least 30 cm depth compared to park soils outside the city centre and rural (arable)soils in the region, which were used to estimate background levels. For example, the mean Hg concentration was 0.9 (max 3.3)mg kg^-1 soil at 0–5 cm and 1.0 (max 2.9) at 30 cm depth in the city centre soils, while the background level was 0,04 mg kg^-1. Corresponding values for Pb were 104 (max 444) and135 (max 339) mg kg^-1, at 0–5 and 30 cm, respectively, while the background level was 17 mg kg^-1.The average soil pools (0–30 cm depth) of Cu, Pb and Zn were 21,38 and 58 g m^-2 respectively, which for Pb was 3–4 timeshigher and for Cu and Zn 1.5–2 times higher than the backgroundlevel. The total amount of accumulated metals (down to 30 cm)in the city centre soils (4.5^*10 ⁶ m² public gardens and green areas) was estimated at 80, 1.1, 120 and 40 t for Cu, Hg, Pb and Zn, respectively. The study showed (1) thatfrom a metal contamination point of view, more homogeneous soilgroups were obtained based on present land use than on geographicdistance to the city centre, (2) the importance of establishing a background level in order to quantify the degree of contamination, and (3) soil samples has to be taken below the surface layer (and deeper than 30 cm) in order to quantify theaccumulated metal pools in urban soils.