Mg/Al/Fe水滑石的焙烧产物对F~-的吸附

采用共沉淀法合成Mg-Al-Fe类水滑石,并通过不同焙烧温度制得焙烧类水滑石。采用XRD,FT-IR,SEM等方法进行了吸附材料表征。研究了焙烧温度,吸附剂投加量,吸附时间,吸附初始p H值,吸附动力学,吸附等温线、吸附热力学等因素对Mg-Al-Fe类水滑石及其焙烧产物吸附F-的效果。研究表明,500℃焙烧类水滑石吸附效果最好,0.2 g吸附剂是最佳投加量值,在p H变化范围为3~8内吸附量基本无变化。研究结果表明,焙烧水滑石吸附符合准二级动力学曲线,反应活化能为E_a=14.63 k J/mol。反应基本符合Langmuir吸附等温模型。△G~0为负值表明该反应是一自发进行过程。高温有利于吸附反应进行。     

含铝活性炭污泥对磷的吸附特性研究

考察了粒径、pH、温度、磷初始浓度等因素对含铝活性炭污泥吸附磷的影响,确定了其吸附过程的热力学和动力学参数。结果表明,含铝活性炭污泥吸附磷的最佳条件为污泥粒径取1.000~2.000mm,温度取25℃,无需调节pH,磷初始质量浓度小于50mg/L。Langmuir方程或Freundlich方程均可以描述含铝活性炭污泥吸附磷的吸附等温线。热力学参数标准吉布斯自由能变(ΔGθ)0J/mol、标准吸附焓变(ΔHθ)0J/mol、标准吸附熵变(ΔSθ)0J/(mol·K)表明,含铝活性炭污泥吸附磷为自发的、吸热的、熵增的过程。吸附动力学研究表明,拟二级动力学模型能够模拟含铝活性炭污泥对磷的吸附过程。     

Mg/Al/Fe复合氧化物吸附去除水体中氟化物的研究

采用水热法合成了不同铁掺杂量的Mg/Al/Fe型类水滑石(MAF),根据X射线衍射(XRD)的测定结果,铁存在一个最佳投加量,铁的掺杂量过大则会导致水滑石的层状结构被破坏。通过扫描电镜(SEM)和比表面分析仪(BET)研究了MAF焙烧后的复合金属氧化物(CMAF)的结构和性能,并考察了CMAF对水中氟离子的吸附性能。与CMA相比(铁掺杂量为零),CMAF对氟离子的吸附去除效率明显提高(最大吸附容量75.2 mg/g),整个吸附过程可以用Langmuir吸附等温线更好地描述。通过XRD测定和晶格参数计算,CMAF的结构由吸附前的复合氧化物恢复到层状水滑石结构,表明氟离子在水滑石重构过程中作为层间阴离子进入到水滑石内部,从而达到较高的除氟效率。     

磁性水滑石快速吸附水体中Cu(Ⅱ)离子

为了探究磁性水滑石对水体中Cu(Ⅱ)离子的去除效果,利用四氧化三铁对水滑石进行磁化,用扫描电子显微镜、X射线衍射仪和傅里叶红外光谱仪表征磁性水滑石。然后,探究磁性水滑石在不同吸附温度、时间、pH、投加量等条件下去除模拟废水中Cu(Ⅱ)的性能。结果表明,磁性水滑石对Cu(Ⅱ)最大吸附量为32.36 mg/g,吸附动力学结果表明,磁性水滑石对Cu(Ⅱ)的吸附在前90 min基本完成。溶液保持pH 5.6~6.5时,磁性水滑石对Cu(Ⅱ)有良好的吸附效率。磁性水滑石可以再生循环利用3~4次。实验证明,磁性水滑石是一种良好的Cu(Ⅱ)吸附剂。     

煅烧的水滑石同时去除水体中砷和氟

为探讨水滑石类材料对水体中氟、砷离子的同时去除效果,采用共沉淀法合成(Mg∶Al=2∶1)纳米类水滑石(LDHs),用傅立叶转换红外光谱、电子扫描透射电镜、X射线晶体衍射等手段对合成的材料进行了表征,并研究纳米材料在不同初始浓度、pH、吸附时间、阴离子干扰条件下其同时除砷氟性能。结果表明,煅烧后的水滑石(LDOs)对砷最大吸附量为51.02 mg/g,对氟最大吸附量为36.63 mg/g。吸附动力学实验表明,煅烧水滑石对砷的吸附在前6 h内基本完成,对氟的吸附在前10 h内基本完成。砷氟共存溶液保持pH=4~10及pH=6~8时,水滑石分别对砷、氟保持良好的吸附效率。对比不同阴离子对水滑石共除砷氟效率的影响,水滑石除砷速率受到阴离子影响力大小为:HPO2-4CO2-3NO-3Cl-SO2-4;水滑石除氟速率受到阴离子影响力大小为:CO2-3HPO2-4SO2-4Cl-NO-3。材料再生循环利用4次后,对砷和氟的吸附效率均能达到90%以上。实验结果表明,所合成的水滑石是一种优秀的能共除砷氟的吸附剂。     

焙烧态锂铝水滑石对水中氟离子吸附性能研究

采用尿素水热法合成了不同摩尔比的锂铝水滑石(Li/Al LDHs),经480℃煅烧后制备出焙烧态锂铝水滑石(Li/AlLDOs)。研究了Li/Al LDOs对水中氟离子的吸附性能,分别考察了吸附时间、吸附温度和pH等因素对吸附效果的影响,并对吸附机制进行了探讨。结果表明,Li/Al LDOs吸附水中氟离子的行为符合准二级动力学方程,吸附等温数据符合Freundlich吸附等温方程,pH对吸附效果影响较大。X射线衍射分析表明,水滑石样品经历了物相转变及重构过程,Li/Al LDOs可有效去除水体中的氟离子。     

磁性Ca/Al水滑石对挥发性脂肪酸的吸附性能

污水脱氮除磷处理过程中使用的液态碳源存在投加量难以控制以及容易影响出水水质、增大处理费用等缺点。针对此现状,采用超声辅助法以超顺磁性铁氧体材料对制备的Ca/Al水滑石进行复合改性合成磁性Ca/Al水滑石,研究以其作为载体对挥发性脂肪酸(VFA)的吸附提取性能,考察了磁性Ca/Al水滑石吸附剂剂量、吸附时间和转速对VFA吸附效果的影响,并通过均匀实验设计,采用响应面法优化吸附提取参数。结果表明:当吸附剂剂量为16 g·L~(-1),吸附时间为50 min,转速为70 r·min~(-1)时,该材料对VFA的理论最大吸附效率为95.7%。由于材料自身具有磁性特性,经提取后的混合液在外加磁场的作用下,能够实现磁性Ca/Al水滑石的快速回收。同时,将回收再生后的磁性Ca/Al水滑石对VFA的吸附提取性能进行了研究,发现在吸附解吸3次循环后仍然有很好的吸附效果。表明利用该磁性Ca/Al水滑石提取VFA是可行的,为后续将其作为固态可控外加碳源的研究奠定了基础。     

磁性水滑石/生物炭复合材料的制备及其对水溶液中磷的吸附性能

以芦苇秸秆生物炭为基体,制备了磁性水滑石/生物炭复合材料(Fe3O4-Mg/Al-LDH/BC)。考察不同pH、Fe3O4-Mg/Al-LDH/BC投加量、初始磷浓度、吸附时间以及反应温度对Fe3O4-Mg/Al-LDH/BC吸附磷的影响。结果表明:Fe3O4-Mg/AlLDH/BC对磷的吸附符合准二级动力学模型和Freundlich模型,吸附过程是自发的吸热反应。在最佳的实验条件下(Fe3O4-Mg/Al-LDH/BC投加量为5.0g/L,磷初始质量浓度为20 mg/L,pH为6.0,温度为30℃,吸附时间为120 min),Fe3O4-Mg/AlLDH/BC对磷的去除率可达99.24%,该材料是一种新型高效的磷吸附材料。     

铁交联累托石处理工业镀锌废水试验研究

介绍了铁交联累托石的制备 ,研究了交联累托石对含锌废水的处理。结果表明 :当交联累托石的用量为 1 2g/L废水、pH =4、常温搅拌吸附 90min时 ,Zn2 + 由 12 2 5mg/L降为 0 97mg/L ,达到国标GHZBI 1999地表水质量一级标准。累托石对Zn2 + 吸附符合Freundlich等温吸附 :Γ =0 34C0 492 3 ,动力学试验表明 :吸附反应为一级反应方程 :lnCt=lnC0 -0 340 6t,其相关系数r =0 95 18,试验测得其热力学函数为 :ΔH =1 91kJ/mol,ΔS =6 90J/mol·K ,ΔG =- 0 16kJ/mol,说明该吸附过程可自发进行     

CoFe_2O_4/MgAl-LDO吸附水中的Cr(Ⅵ)

采用水热法、共沉淀法合成Co Fe2O4/Mg Al-LDH,于高温下焙烧4 h后,制备出同时具有高吸附性能和磁分离性能的镁铝复合氧化物(Co Fe2O4/Mg Al-LDO),研究其对水中Cr(Ⅵ)的吸附效果。采用X射线衍射(XRD)、红外光谱(FTIR)等技术对吸附剂进行表征。通过序批实验考察了焙烧温度、溶液初始p H值、吸附时间、温度等因素对Co Fe2O4/Mg AlLDO吸附Cr(Ⅵ)的影响。结果表明,当焙烧温度在450~550℃之间、溶液初始p H=2~6时,吸附剂对Cr(Ⅵ)均具有较好的吸附效果,且吸附反应在90 min内达到平衡。Co Fe2O4/Mg Al-LDO吸附Cr(Ⅵ)过程符合准二级动力学和Langmuir等温吸附模型,当温度为318 K时,理论饱和吸附容量为98.04 mg/g。热力学研究结果表明,该吸附过程为自发的、吸热反应过程。     

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.     

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.     

Organochlorine compounds in a three-step terrestrial food chain

The concentrations of 15 organochlorine chemicals (PCBs and pesticides) were studied in a Central European oak wood food chain system: Great tit (Parus major), caterpillars (Tortrix viridana, Operophtera brumata, Erannis defoliaria), and oak-leaves (Quercus robur). Juvenile tits receive organochlorines from the mother via egg transfer and, eventually to a greater extent, from the caterpillar food source during nestling period. The concentrations of PCB 153 (2,2′,4,4′,5,5′-hexachlorobiphenyl, the most abundant in this study) was found in leaf material at ca. 1 ng/g, in caterpillars 10 ng/g, and in bird eggs 170 ng/g on an average and on a dry mass basis.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.     

Radionuclides in pinon pine (Pinus edulis) nuts from los alamos national laboratory lands and the dose from consumption

Abstract

One of the dominant tree species growing within and around the eastern portion of Los Alamos National Laboratory (LANL), Los Alamos, NM, lands is the pinon pine (Pinus edulis). Pinon pine is used for firewood, fence posts, and building materials and is a source of nuts for food—the seeds are consumed by a wide variety of animals and are also gathered by people in the area and eaten raw or roasted. This study investigated the (1) concentration of ³H, ¹³⁷Cs, ⁹⁰Sr, ^totU, ²³⁸Pu, ^{239, 240}Pu, and²⁴¹ Am in soils (0‐ to 12‐in. [31 cm] depth underneath the tree), pinon pine shoots (PPS), and pinon pine nuts (PPN) collected from LANL lands and regional background (BG) locations, (2) committed effective dose equivalent (CEDE) from the ingestion of nuts, and (3) soil to PPS to PPN concentration ratios (CRs). Most radionuclides, with the exception of ³H in soils, were not significantly higher (p < 0.10) in soils, PPS, and PPN collected from LANL as compared to BG locations, and concentrations of most radionuclides in PPN from LANL have decreased over time. The maximum net CEDE (the CEDE plus two sigma minus BG) at the most conservative ingestion rate (10 lb [4.5 kg]) was 0.0018 mrem (0.018 μSv); this is far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem (1000 μSv). Soil‐to‐nut CRs for most radionuclides were within the range of default values in the literature for common fruits and vegetables.     

Degradation and sorption of imidacloprid in dissimilar surface and subsurface soils

Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. This research characterized the degradation and sorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine) in Drummer (silty clay loam) and Exeter (sandy loam) surface soils and their corresponding subsurface soils using sequential extraction methods over 400 days. By the end of the incubation, approximately 55% of imidacloprid applied at a rate of 1.0 mg kg^?1 degraded in the Exeter sandy loam surface and subsurface soils, compared to 40% of applied imidacloprid within 300 days in Drummer surface and subsurface soils. At the 0.1 mg kg^?1 application rate, dissipation was slower for all four soils. Water-extractable imidacloprid in Exeter surface soil decreased from 98% of applied at day 1 to > 70% of the imidacloprid remaining after 400 d, as compared to 55% in the Drummer surface soil at day 1 and 12% at day 400. These data suggest that imidacloprid was bioavailable to degrading soil microorganisms and sorption/desorption was not the limiting factor for biodegradation. In subsurface soils > 40% of ¹⁴C-benzoic acid was mineralized over 21 days, demonstrating an active microbial community. In contrast, cumulative ¹⁴CO₂ was less than 1.5% of applied ¹⁴C-imidacloprid in all soils over 400 d. Qualitative differences in the microbial communities appear to limit the degradation of imidacloprid in the subsurface soils.     

Biochemical interaction of six op delayed neurotoxicants with several neurotargets

Abstract

Five organophosphorous insecticides: Leptophos, EPN, Cyano‐fenphos, trichloronate and salithion proved to cause irreversible ataxia not only to chicken but also to mice and sheep. TOCP was included as a reference. Cyanofenphos blocked the catecholamine B‐receptor binding activity with ³H‐norepinephrine at a level similar to that of the specific inhibitor propranolol in the mouse heart preparation. In the lamb heart preparation, the B‐receptor was more sensitive to Leptophos, salithion and TOCP than to propranolol. The six compounds and their oxons were screened for their in‐vitro inhibition to monamine oxidase (MAO), acetyl cholinesterase (AChE) and neurotoxic esterase (NTE) in the brain of either mouse, lamb or chicken. It is believed that their AChE inhibition stands for their acute toxicity, while NTE inhibition is responsible for their paralytic ataxia.     

土壤中砷的化学平衡

本文比较详细地综述了砷的化学特性,环境背景值及来源和循环,土壤中砷的三大化学平衡即沉淀溶解平衡,氧化还原平衡,吸附解吸平衡,以及微生物对砷的转化。     

Elemental uptake by edible herbs and lettuce (Latuca sativa)

The total concentration of toxic elements (aluminum, cadmium, chromium and lead) and selected macro and micro elements (iron, manganese, copper and zinc) are reported in six leafy edible vegetation species, namely lettuce, spinach, cabbage, chards and green and red types of Amaranth herbs. Although spinach and chards had greater than 125 mv of iron, both the amaranthus herbs recorded > than 320 μ g g^{? 1} dry weight. In both the spinach and chard species, the Mn and Zn levels were appreciable recording > 225 μ g g^{? 1} and 150 μ g g^{? 1} dry weight, respectively. Aluminum concentrations were (in μ g g^{? 1} dry weight) lettuce (10), cabbage (11), spinach (167), chards (65), amaranthus green (293) and amaranthus red (233). All the micro and macro elements and the toxic elements (Ni, Cr, Cd and Pb) elements analyzed, were below the recommended maximum permitted levels (RMI) in vegetables. Further the elemental uptake and distribution of the nine elements, at three growth stages of the lettuce plant grown on soil bed under controlled conditions are detailed. In the soil, except for iron (16%), greater than 33% of the other cations were in exchangeable form. Generally in the lettuce plant, roots retained much of the iron (> 224 μ g g^{? 1}) and aluminum (> 360 μ g g^{? 1}), while leaves had less than 200 μ g g^{? 1} of iron and 165 μ g g^{? 1} of Al. Although the concentrations of elements marginally decreased with growth, the lettuce leaves had significant amounts of Mn (30 μ g g^{? 1}), Zn (50 μ g g^{? 1}) and Cu (3.6 μ g g^{? 1}). Some presence of lead in leaves (2.0 μ g g^{? 1}) was noticed, but all the toxic and other elements analyzed were well below the RMI values for the vegetables.     

The dissipation of nonlyphenol in stream and pond water under simulated field conditions

Abstract

The dissipation of 1.0 ppm nonylphenol in stream and pond water, incubated in flasks at 16°C under simulated field conditions up to 44 days indicated that the half‐life was 2.5 days if the flasks were open, and 16 days if they were closed. A transformed product was detected in the closed flasks.

Translocation of nonylphenol in water occurred when treated water samples were incubated in the presence of sediment. After 10 days, nonylphenol was detected only in the sediment, but not in water (detection limit = 10 ppb). About 80% of the nonylphenol was degraded in 71 days, but no degradation occurred if the water and the sediment were autoclaved prior to incubation.