污泥基活性炭吸附Cu2+的应用研究

以城市污水处理厂剩余污泥为原料,以ZnCl₂为活化剂制取污泥基活性炭。以此污泥基活性炭为吸附剂,对含Cu²⁺的废水进行了吸附实验研究。考察了溶液pH值、Cu²⁺的起始浓度对Cu²⁺离子吸附量的影响;利用等温吸附实验作出吸附等温线,并考察了污泥基活性炭吸附剂吸附Cu²⁺的动力学方程。实验结果表明,污泥基活性炭对Cu²⁺具有良好的吸附性能。吸附的最佳pH值为5;吸附符合Langmuir和Freundlich吸附等温方程,吸附为优惠吸附,吸附量随着吸附质溶液浓度的增加而增大;吸附平衡时间为4 h,吸附动力学符合二级动力学方程。     

丙烯酸改性壳聚糖磁性颗粒处理模拟废水中氨氮

以去除水产养殖废水中的氨氮,寻找安全快速高效的吸附剂为目的。以壳聚糖为原料制备丙烯酸改性壳聚糖磁性颗粒,采用单因素及正交实验方法优化制备条件,研究振荡吸附条件对吸附量的影响,进行吸附等温模型和吸附动力学研究。结果表明,最佳制备条件,丙烯酸4 mL、磁流体0.75 g、过硫酸铵1 g、戊二醛1.5 mL;最佳吸附条件,废水pH值5~9、吸附剂浓度3 g/L、吸附时间10 min;吸附过程符合二级动力学模型,以化学吸附为主;液膜扩散为限速步骤;氨氮最大吸附量为77.16 mg/g,远高于其他传统吸附剂。研究表明,丙烯酸改性壳聚糖磁性颗粒对模拟水产养殖废水的氨氮去除效果显著,具有很好的应用前景。     

锆(Ⅳ)负载交联壳聚糖吸附硫酸根的性能

以甲醛、苯甲醛为交联剂,制备交联壳聚糖树脂,再与锆(Ⅳ)离子反应制备锆负载交联壳聚糖吸附剂。采用静态吸附法考察了该吸附剂对水中硫酸根离子(SO24-)的吸附性能。实验发现,吸附时间2 h,SO24-溶液初始浓度500 mg/L,pH值3.0,溶液温度35℃为较优的吸附条件;吸附过程符合Langmuir等温吸附模型,属于优惠吸附型,吸附容量可达78.65 mg/g;吸附过程较好地符合拟二级动力学模型;锆负载前后交联壳聚糖对硫酸根的吸附量提高了约4.5倍;该吸附剂具有良好的耐酸性和再生性能。     

利用质子化的水杨醛接枝壳聚糖吸附水中硫酸根

以水杨醛（邻羟基苯甲醛）接枝壳聚糖为基础制备出质子化改性壳聚糖,研究其对硫酸根离子（SO24-）的吸附性能。通过静态吸附实验进行了吸附条件的优化以及吸附等温方程研究,用扫描电镜（SEM）和红外光谱（FTIR）对产物进行了表征,并对吸附机理进行了初步探讨。优化的吸附条件为：吸附时间为40min,SO24-溶液初始浓度500mg／L,pH值为5．0,反应温度为35℃;吸附等温方程研究表明,吸附过程符合Langmuir型,吸附容量为107．53mg／g。SEM和红外光谱分析表明：SO24- 主要是被吸附到壳聚糖的氨基上的。     

铜-胺改性ZSM-5吸附剂的制备及其对NOx的净化机理

以ZSM-5分子筛粉体为原料,成型后负载铜盐和有机胺改性,制备出一种高效脱除氮氧化物的吸附剂。通过改变铜盐、有机胺的含量以及铜盐活化温度使吸附剂的性能得到优化,在实验条件下（NO₂初浓度1 000 mg/m³,气流2.7 L/min）床层对NO₂动态吸附的透过时间由改性前的3 min提高到90 min,并使NO气体的释放得到有效减缓。通过动态吸附实验研究了NO释放时间在负载前后的变化,通过X射线光电子能谱（XPS）和红外分析（FTIR）研究了吸附剂表面铜元素、有机基团等在吸附前后的变化规律,提出了可能的净化机理。     

污泥吸附剂对3种染料吸附动力学的研究

以污水厂脱水污泥、锯末和焦油的混合物为原料,选择ZnCl₂为活化剂制备出过渡孔发达、强度大的污泥吸附剂（S-AC）。借助BET、FT-IR等现代分析测试方法对污泥吸附剂进行表征,同时,研究了吸附剂对酸性大红、中性红和碱性品红吸附动力学行为。结果表明,制得的污泥吸附剂BET比表面积为358 m²/g,强度大于89%。吸附剂的动力学数据均符合伪二阶动力学方程、液膜扩散方程和颗粒内扩散方程,其中液膜扩散为吸附剂对酸性大红吸附过程的主控步骤,颗粒内扩散为吸附剂对中性红和碱性品红吸附过程的主控步骤。     

壳聚糖联合碱改性粉煤灰对重金属离子的吸附特性

采用浸渍法将壳聚糖负载在经NaOH改性的粉煤灰上,制备了联合改性的粉煤灰。随粉煤灰上壳聚糖负载量的增加,粉煤灰对Pb²⁺和Cd²⁺的吸附率均提高。当负载壳聚糖的质量分数为8%,吸附温度为30℃,吸附时间为120 min时,粉煤灰对Pb²⁺的吸附率最高（为98.9%）,对Cd²⁺的吸附率也最高（为91.5%）。其吸附行为符合Freundlich等温吸附模型,但表现为2个线性区。粉煤灰负载壳聚糖的改性机理是粉煤灰与带正电荷的壳聚糖的化学键合作用。     

ZnCl2法污泥含炭吸附剂对模拟烟气中气态汞的吸附

采用改进的ZnCl₂化学活化法制备污泥含炭吸附剂,利用EDS以及氮吸附等多种测试手段对所制得的污泥含炭吸附剂进行表征,并利用其处理模拟烟气汞污染物,实验结果表明,污泥含炭吸附剂对Hg0的吸附包括物理吸附作用和化学吸附作用,以物理吸附作用为主;随着Hg0入口浓度的提高,污泥含炭吸附剂的Hg0饱和吸附容量增大;随着吸附反应温度的升高污泥含炭吸附对Hg0的吸附作用减弱;在吸附反应温度125℃,Hg0入口浓度60.4 μg/m³,污泥含炭吸附剂和选定的活性炭对Hg0的吸附容量分别为81.2 μg/g和53.8 μg/g,污泥含炭吸附剂对Hg0的吸附作用好于选定的活性炭。     

MWNTs及MWNTs/TiO2对水中1,2,3-三氯苯的吸附特性研究

采用批量平衡实验,对比研究了多壁碳纳米管（MWNTs）及多壁碳纳米管/二氧化钛复合材料（MWNTs/TiO₂）对水中1,2,3-三氯苯的吸附特性。结果表明,在相同条件下,MWNTs及MWNTs/TiO₂对1,2,3-三氯苯（1,2,3-TCB）的最大吸附量分别为71.8 mg/g和3.05 mg/g,pH值在2~11之间变化时,两者的吸附均不受pH值变化的影响。2种吸附剂的吸附过程均符合拟二级动力学方程,但MWNTs/TiO₂对1,2,3-TCB的吸附速率常数为0.4159 g/(mg·min),约为MWNTs的50倍左右,说明MWNTs/TiO₂具有更强的吸附驱动力。1,2,3-TCB在2种吸附剂上的吸附过程均可用Freundlich吸附等温线来描述,其热力学参数吉布斯自由能△G⁰均为负、标准焓变△H⁰与熵变△S⁰均为正表明,MWNTs及MWNTs/TiO₂吸附1,2,3-TCB过程为自发吸热反应。与MWNTs相比,MWNTs/TiO₂具有可光催化再生的优点,能用于被污染水体的原位修复。     

铁-镧系合金氧化物污水除磷及再生简

采用共沉淀法制备了系列铁-镧系合金氧化物并研究其除磷能力。结果表明：以铁、镧摩尔比为0.08的吸附剂除磷能力最强,吸附曲线适合Langmuir等温线方程。该吸附剂的吸附量受pH影响显著,pH在4.0~7.0之间时吸附量较大。进行了抗共存阴离子能力测试,结果表明CO₃^2-对磷吸附量影响较大,给出了共存阴离子对吸附量的影响顺序。对该吸附剂进行了真空高温再生,再生率最高可达62.27%。     

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.