微波强化有机改性膨润土对磷的吸附特性研究

利用十六烷基三甲基溴化铵(CTMAB)在微波辐射条件下对浙江临安膨润土进行改性,制得有机改性膨润土,利用其含磷模拟废水进行处理,考察了不同的工艺条件如有机改性剂用量、微波辐射强度、辐照时间、吸附时间、改性膨润土投加量、pH值对废水中磷去除效果的影响。结果表明:在有机改性剂用量为3 mmol/g,微波辐照强度为96 W/g,微波辐照时间8 min为最佳制备条件。改性膨润土用量为12 mg/L,反应时间为15 min,溶液pH为7及常温条件下,改性膨润土对浓度为50 mg/L的含磷废水去除率达到97.3%,吸附符合Freundlich吸附等温方程。     

阳离子表面活性剂改性油茶果壳对水溶液中甲基橙的吸附

以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)对油茶果壳进行改性,制备CTAB-油茶果壳(CTABCOS)吸附材料,并采用批实验法对其对水溶液中甲基橙的吸附去除进行了研究。考察了溶液p H、吸附剂用量和离子强度等对水溶液中甲基橙的吸附影响,并研究了体系的吸附动力学和吸附热力学特征。结果表明,向100 m L浓度为50 mg/L的甲基橙溶液中加入0.40 g CTAB-COS,在最佳实验条件下,CTAB-COS对甲基橙的去除率可达96.66%。溶液离子强度增大,甲基橙去除率降低。CTAB-COS对甲基橙的吸附行为符合拟二级动力学模型,吸附等温线可用Langmuir模型进行较好拟合,在20℃时最大吸附量为18.31 mg/g。吸附热力学结果表明,吸附过程为可自发进行的放热过程。再生性实验结果表明,再生6次后,CTAB-COS对甲基橙的吸附去除率仍可达到80%。该改性油茶果壳可应用于阴离子型染料废水的吸附法处理。     

改性凹凸棒土的优化定向制备及对腐殖酸的吸附效果

以天然凹凸棒土为原料,以去除以腐殖酸为代表的天然有机物为目的,研究酸活化、热处理和十八烷基三甲基氯化铵(OTAC)有机改性3种改性方法,进行定向筛选。进一步比较3种方法联合改性凹土后对腐殖酸的吸附效果,确定最优定向改性方法。结果表明,先酸处理后OTAC改性凹土对腐殖酸的吸附效果最好,改性凹土投药量为0.7 g/L时,腐殖酸的去除率可达97%。利用正交实验确定凹土改性的最佳工艺条件、钠化时间和有机改性剂的用量对改性凹土吸附腐殖酸的能力影响显著。改性的最佳工艺条件为:酸浓度3 mol/L,氯化钠浓度0.5 mol/L,钠化时间2 h,改性剂用量为凹土质量的3%,微波改性时间为9 min。单独投加改性凹土时p H值对腐殖酸的吸附效果有重要影响。该方法制备的改性凹土在水处理工艺有良好的应用前景。     

铁镍改性膨润土对废水中有机污染物的吸附性能研究

以钠基膨润土为原料,制备了铁镍无机改性土和铁镍有机复合改性土,并应用于造纸废水的处理,探讨了改性土用量、废水pH值、搅拌时间等因素对COD去除率的影响,通过正交实验对实验条件进行了优化.结果表明:铁镍有机复合改性土和铁镍元机改性土对废水的处理效果明显好于原土;膨润土的用量、废水的pH对COD的去除率影响较大;对于铁镍无机改性土,吸附剂用量为12g/L,溶液pH=2,吸附时间为10 min时,对废水中COD的去除率为54.06%;对于铁镍有机复合改性土,吸附剂用量为14g/L,溶液pH=3,吸附时间为20 min时,对废水中COD的去除率为70.10%.     

铁镍改性膨润土对废水中有机污染物的吸附性能研究

以钠基膨润土为原料,制备了铁镍无机改性土和铁镍有机复合改性土,并应用于造纸废水的处理,探讨了改性土用量、废水pH值、搅拌时间等因素对COD去除率的影响,通过正交实验对实验条件进行了优化.结果表明：铁镍有机复合改性土和铁镍元机改性土对废水的处理效果明显好于原土;膨润土的用量、废水的pH对COD的去除率影响较大;对于铁镍无机改性土,吸附剂用量为12g/L,溶液pH=2,吸附时间为10 min时,对废水中COD的去除率为54.06%;对于铁镍有机复合改性土,吸附剂用量为14g/L,溶液pH=3,吸附时间为20 min时,对废水中COD的去除率为70.10%.     

改性粉煤灰处理低浓度含磷废水的研究

以酸改性粉煤灰为吸附剂,处理低质量浓度(1 mg/L左右)磷酸盐溶液,探讨了改性剂的种类、改性剂用量、吸附剂用量、反应时间、pH以及温度对除磷效果的影响.结果表明:(1)经过酸改性后粉煤灰的磷去除率显著提高,而且硫酸改性粉煤灰的除磷效果更好,磷去除率最高可达97.68％.(2)最佳条件:选择硫酸用量为5 mL/g进行改性,硫酸改性粉煤灰投加量为2.0g,反应时间为60 min,pH为7.2～10.8,温度为25℃(即室温).(3)改性粉煤灰对磷的吸附更符合Freundlich吸附等温模型,既有物理吸附,也有化学吸附,并以Ca、Mg氧化物与磷形成磷的沉淀物为主.     

改性玉米芯吸附溶液中的铀

以KMnO4改性玉米芯为吸附剂来吸附溶液中的铀,并与未改性玉米芯的吸附能力进行比较。考察了玉米芯用量、溶液pH值、铀初始质量浓度以及吸附时间等因素对铀吸附效果的影响。实验结果表明,当溶液pH=5.5、改性玉米芯用量为0.12 g、未改性玉米芯用量为0.2 g、铀初始质量浓度为30 mg/L、接触时间为2.5 h时,改性玉米芯对铀的去除率为93.54%,未改性玉米芯对铀的去除率为59.68%,改性玉米芯对铀的吸附效果明显优于未改性玉米芯。     

改性膨润土联合混凝剂处理微污染水中有机物

采用十二烷基多糖苷季铵盐作为改性剂制备改性膨润土,研究了改性膨润土联合混凝剂去除有机物的效果,考察了有机改性剂用量、微波辐射功率、辐射时间、膨润土投加量、pH值对有机物去除效果的影响,探讨了改性膨润土的改性和去除机理。结果表明,经微波改性后,实现了十二烷基多糖苷季铵盐阳离子对膨润土的插层,增大了层间距,提高了膨润土的吸附性能。联合混凝剂投加改性膨润土能够改善絮凝性能,显著提高有机物的去除效果。在最佳条件下,改性膨润土与PAC联合后的强化混凝,对初始浓度15.3 mg/L的微污染水中有机物的去除率达到95%以上,吸附符合Freundlich吸附等温方程。     

表面活性剂改性活性炭对阳离子染料的吸附

以阴离子表面活性剂十二烷基硫酸钠(SDS)为改性剂对粉末活性炭(AC)改性,研究了SDS在活性炭表面的吸附稳定性,用比表面积测定仪、Zeta电位测定仪对改性前后活性炭进行表征,并将其用于吸附模拟废水中的阳离子染料。结果表明,改性剂SDS浓度等于临界胶束浓度时,改性后活性炭(SDS-AC)对SDS吸附稳定,SDS在纯水和染料溶液中的解吸率分别为19.4%和1.6%。pH对活性炭吸附阳离子橙染料影响较小,SDS-AC和AC对染料的吸附平衡时间分别为4 h和12 h,SDS-AC和AC对阳离子橙染料的吸附动力学模型符合拟二级反应模型,吸附等温线更符合Langmuir吸附等温方程,SDS-AC对阳离子橙染料的最大吸附量较AC提高47.8%,SDS-AC对阳离子橙染料的吸附机制为物理吸附和化学吸附共同作用下的单分子层吸附,其中化学吸附是主要控速步骤。     

改性锰矿的除砷性能研究

利用共沉淀—煅烧法对天然锰矿进行改性,研究了铁锰摩尔比(Fe/Mn)、pH、温度、共存离子对改性锰矿除砷效果的影响。采用X射线荧光光谱(XRF)、傅立叶红外光谱(FTIR)、扫描电镜(SEM)对其进行表征,探究改性锰矿除砷机理。结果表明:(1)Fe/Mn为12∶1时对As(Ⅲ)有最大去除率(88.63%),4∶1时对As(Ⅴ)有最大去除率(84.25%)。(2)弱酸性、中性及弱碱性的溶液反应环境有助于改性锰矿对砷的吸附。(3)Ca~(2+)促进砷吸附,HCO_3~-抑制砷吸附。(4)改性锰矿对砷的吸附过程符合Langmuir吸附等温方程和二级动力学方程。(5)可利用Na_2CO_3溶液对改性锰矿进行再生解吸,再生5次后的改性锰矿对As(Ⅲ)和As(Ⅴ)的去除率分别为81.27%、75.99%。     

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.     

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.     

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.     

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.     

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.     

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.