磁性膨润土的制备、表征及类Fenton催化降解橙黄Ⅱ

以铝柱撑膨润土和铁盐为原料,采用共沉淀法制备纳米Fe3O4负载的磁性膨润土复合材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和比表面孔隙分析(BET)对样品进行表征,研究了磁性膨润土对橙黄Ⅱ的类Fenton催化降解性能,并考察了催化剂用量、温度和初始pH、H2O2初始浓度等因素对降解效果的影响。结果表明,Fe3O4均匀负载在膨润土表面,未发生明显团聚,并且改善了膨润土的孔隙结构,增加了其比表面积。在磁性膨润土用量为0.6 g/L,温度为40℃,pH为3.0,H2O2初始浓度为21 mmol/L的条件下,0.5 mmol/L橙黄Ⅱ溶液在180 min内色度去除率和UV254去除率分别达到100%和97%,且催化剂重复使用4次效果稳定。     

硬脂酸改性磁铁矿在含油污水处理中的应用

研究了水溶液中硬脂酸改性后磁铁矿吸附石油的特性,测定了温度、改性剂用量和时间等因素对改性以及吸附的影响,并对吸附后磁铁矿进行了再生。通过对红外图谱、扫描电镜图谱等的分析,对改性及吸附机理进行了探讨。结果表明,硬脂酸改性磁铁矿的最佳改性条件为常温20℃,改性时间45 min,改性剂用量硬脂酸与磁铁矿的质量比为4%,改性过程中伴随着物理和化学变化,硬脂酸在磁铁矿表面形成了双分子层包覆。改性后的磁铁矿表面湿润性降低,改性磁铁矿吸附石油符合Langmu ir型吸附等温线,最大吸附量为749.23 mg/g,最大去除率达93%。对饱和吸附后的改性磁铁矿经再生处理后,石油去除率稳定在85%。     

一株石油降解菌的活性炭纤维固定化研究

以活性炭纤维为固定化载体将一株石油降解菌固定化,对固定化后的与游离的石油降解菌的石油降解性能进行了研究.结果表明,石油降解菌固定化的最佳活性炭纤维用量为6.25 g/L;当石油培养基盐度为0～3.5%、pH为7、石油用量为5 g/L时,当石油培养基盐度为0、pH为4～10、石油用量为5 g/L时,当石油培养基盐度为0、pH为7、石油用量为1～13 g/L时,最佳活性炭纤维用量下的固定化后的石油降解菌对石油的平均去除率分别比游离的石油降解菌高30.2%、25.4%、23.2%;同一批固定化后的石油降解菌在连续4次的重复利用中,石油去除率均维持在69.1%以上.     

磁性活性炭的制备及其对水中甲基橙的吸附

活性炭被广泛应用于水处理领域,然而吸附饱和后难以分离和再生的缺点却限制了其应用。本研究采用化学共沉淀法将铁氧化物和活性炭进行复合,制备出同时具有磁分离性能和较强的吸附性能的磁性活性炭复合材料,并对制备的复合材料进行表征,考察其对水中甲基橙的吸附性能。结果表明,制备的磁性活性炭的比表面积为666.72 m2/g,平均孔径为3.16 nm,具有良好的磁性能,在外加磁场下能快速地从溶液中分离出来且磁性能相对稳定,铁氧化物对活性炭吸附性能的影响不大。在温度为25℃、p H为5、吸附剂用量为3 g/L的情况下,吸附3 h后,该磁性活性炭对甲基橙的吸附率可达99.1%,预示着该磁性活性炭在水处理方面具有潜在的应用前景。     

转炉钢渣中铁组分的氧化改质与磁选回收

在不同工艺参数下对转炉钢渣进行了固相氧化改质,并对改质后钢渣进行了磁选处理,分析对比了干式磁选和湿式磁选对改质钢渣的磁选效果。实验结果表明:通过氧化改质处理,能够使钢渣中无磁性铁氧化物向有磁性镁铁尖晶石发生转变,后者可通过磁选进行有效分离。原钢渣进行氧化改质的最佳加热温度和气体通入速率分别为1 100℃和7.5 L·min~(-1)。钢渣通过固相改质后,更容易获得高回收率的高品位精矿,对钢渣的磁选宜为湿式弱磁选,实验范围内磁选工艺的最佳磁感应强度为0.102 T。在加热温度1 100℃,保温时间30 min,气体通入速率7.5 L·min~(-1)的条件下,改质钢渣产率达到22%,铁品位达到62%,回收率达到64.95%。     

磁性硅藻土的制备及其性能

针对现有硅藻土吸附容量小和固液分离难的问题,采用共沉淀法制备2种磁改性硅藻土:Ⅰ和Ⅱ,通过扫描电镜(SEM)、比表面积测定(BET)、X射线衍射(XRD)等对制备的磁性硅藻土进行结构分析,并采用磁滞回线评估其磁性;考察了溶液pH、吸附剂用量和吸附时间对其吸附硝基苯的影响以及吸附饱和后的固液分离性能。结果表明:2种磁改性样品的饱和磁化强度分别为26.28 emu/g和4.8 emu/g,比表面积分别为39.242 m~2/g和60.588 m~2/g,为原土的1.3倍和2倍;对硝基苯的去除率分别达74.95%和95.2%,为原土的1.8倍和2.3倍;吸附饱和的磁改性样品在外加磁场作用下可迅速实现固液分离,且分离后2种磁改性样品溶液的悬浮物浓度分别为8.6 mg/L和9.8 mg/L。     

两相分配式生物反应器处理高盐废水中的苯酚

采用新型两相分配式生物反应器(TPPB)和前期研究得到的高效苯酚降解菌对高盐废水中苯酚的降解进行研究,研究中确定煤油为反应系统的最佳有机溶剂,并考察了废水苯酚含量、废水盐度以及搅拌器搅拌速度对苯酚降解的影响。结果表明,反应系统能正常降解苯酚含量为1 000～2 500 mg/L的高盐苯酚废水;反应系统在含盐量为100 g NaCl/L、搅拌速度为50 r/min的运行工况条件下,降解时间缩短为52 h,总酚去除率为20.58 mg/(L.h)。     

紫外催化湿式氧化工艺降解油墨废水

为了解决传统催化湿式过氧化氢氧化技术需要高温高压等苛刻条件的问题,将紫外引入催化湿式氧化技术,得到可在常温常压条件下进行的紫外催化湿式氧化工艺(UV-CWOP)。以Cu2+为催化剂,采用该工艺处理油墨废水取得了良好的效果。通过单因素实验确定的最佳工艺条件为:pH值=3,H2O2用量为1.5倍理论量,CuSO4.5H2O投量2 g/L,初始温度40℃。在此条件下处理油墨废水3 h,COD可从9 500 mg/L降解到89 mg/L,出水达到国家《污水综合排放标准》(GB8978-1996)一级标准。     

聚(丙烯酸-co-丙烯酰胺)/膨润土/腐植酸钠三维网络凝胶吸附剂对Cd2+吸附性能研究

制备了一种聚(丙烯酸-co-丙烯酰胺)/膨润土/腐植酸钠三维网络凝胶吸附剂,重点考察了吸附剂对Cd2+吸附的pH依赖性、吸附动力学和吸附等温线.结果表明,Cd2+溶液pH值对吸附容量有较大影响.在pH=8、吸附时间30 min、Cd2+溶液初始浓度0.02 mol/L和吸附剂用量0.10 g的条件下,吸附剂对Cd2+的饱和吸附量可达294.7 mg/g.与膨润土相比,三维网络凝胶吸附剂具有更高的吸附容量和更快的吸附速率.     

ClO2氧化/TiO2复合吸附剂协同体系处理印染废水的实验研究

利用ClO2 氧化/TiO2 复合吸附剂协同体系对处理实际印染废水进行了实验研究.结果表明,对于COD为750 mg/L、色度为250倍、SS为100 mg/L的1 000 mL印染废水,当溶液pH为4.0、ClO2 用量20 mg/L、TiO2 复合吸附剂用量2.5 g、反应时间和吸附时间分别为2、8 min时,处理后的废水COD＜100 mg/L、色度＜40倍、SS＜70 mg/L,达到了《纺织染整工业水污染物排放标准》(GB 4287-92)排放要求.并对两者的协同机理进行了理论上的探讨.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

Teratological effects of pesticides in vertebrates: a review

Abstract

In the last decades, the use and misuse of pesticides in the agriculture have increased, having a severe impact on ecosystems and their fauna. Although the various effects of pesticides on biodiversity have been already documented in several studies, to our knowledge no consistent overview of the impact of pesticides in vertebrates, both terrestrial and aquatic, is available. In this review, we try to present a concise compilation of the teratogenic effects of pesticides on the different classes of vertebrates – mammals, birds, reptiles, amphibians and fish.     

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos national laboratory and the doses to humans from the consumption of muscle and bone

Abstract

The purpose of this study was to determine radionuclide and trace element concentrations in bottom‐feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for ³H, ⁹⁰Sr, ¹³⁷Cs, ^totU, ²³⁸Pu, ^239,240Pu, and ²⁴¹Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of ⁹⁰Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p<0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium‐90 in fish muscle plus bone tissue significantly (p<0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E‐02 pCi g^‐1 [126E‐02 Bq kg^‐1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E‐02 pCi g^‐1 [518E‐02 Bq kg^‐1]). The differences in ⁹⁰Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (±2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 ± 0.1 mrem y^‐1 (1.0 ± 1.0 μSv y^‐1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y^‐1 (1000 μSv y^‐1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p<0.05) concentrations than in muscle of fish collected from background locations.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

Knowledge transfer initiative between molecular biologists and environmental researchers and regulators

A Natural Environment Research Council (NERC) funded Knowledge Transfer (KT) workshop was held in the United Kingdom (UK) to identify the needs and opportunities in the application of molecular biology and ‘omics’ techniques to environmental monitoring and risk assessment. Attendees highlighted a lack of effective communication between end-users and researchers as well as difficulties with data interpretation as reasons behind the slow uptake of molecular biology and omics techniques. A number of promising areas in which new techniques could be implemented at a practical level in the very near future were identified, thereby raising the profile of these recent technologies and providing vital proof of concept work. Molecular taxonomy, bacterial source tracking and pre-screening of chemicals for potential toxicities were all viewed as areas in which omics and molecular techniques could have immediate value, with the aim of reducing cost, increasing efficiency and providing more comprehensive data of improved quality.     

Sorption and predicted mobility of herbicides in Baltic soils

This study was undertaken to determine sorption coefficients of eight herbicides (alachlor, amitrole, atrazine, simazine, dicamba, imazamox, imazethapyr, and pendimethalin) to seven agricultural soils from sites throughout Lithuania. The measured sorption coefficients were used to predict the susceptibility of these herbicides to leach to groundwater. Soil-water partitioning coefficients were measured in batch equilibrium studies using radiolabeled herbicides. In most soils, sorption followed the general trend pendimethalin > alachlor > atrazine～ amitrole～ simazine > imazethapyr > imazamox > dicamba, consistent with the trends in hydrophobicity (log K_ow) except in the case of amitrole. For several herbicides, sorption coefficients and calculated retardation factors were lowest (predicted to be most susceptible to leaching) in a soil of intermediate organic carbon content and sand content. Calculated herbicide retardation factors were high for soils with high organic carbon contents. Estimated leaching times under saturated conditions, assuming no herbicide degradation and no preferential water flow, were more strongly affected by soil textural effects on predicted water flow than by herbicide sorption effects. All herbicides were predicted to be slowest to leach in soils with high clay and low sand contents, and fastest to leach in soils with high sand content and low organic matter content. Herbicide management is important to the continued increase in agricultural production and profitability in the Baltic region, and these results will be useful in identifying critical areas requiring improved management practices to reduce water contamination by pesticides.