电催化氧化法降解苯酚废水的实验研究

应用自制电化学反应器对废水中苯酚的电催化氧化处理进行了研究，实验了阳极材料、电流密度、电解时间、电极间距离、废水pH值、废水电导率等对苯酚电解去除效果的影响，确定了最佳的处理条件。在电流密度为30mA／cm^2,电解时间为80min，电极间距离为2cm，废水pH值在7～8之间，废水电导率为1100μs／cm的处理条件下，苯酚的电解处理去除率可达97％以上。利用TOC测定仪、紫外光谱和红外光谱等仪，器分析的方法对苯酚降解过程中的产物进行了分析。     

La掺杂SnO2/Ti电极电催化降解邻硝基苯酚

采用凝胶一溶胶法制备了La掺杂SnO2/Ti电极并用于邻硝基苯酚废水的电解研究.分析了电流密度、电极距离、溶液初始pH对邻硝基苯酚电解效果的影响,确定了最佳电解条件.结果表明,La/Sn(摩尔比)为0.03,热处理温度为450℃下制备的La掺杂SnO2/Ti电极对邻硝基苯酚的降解效果最好.当电流密度为20 mA/cm2,电极距离为2 cm,溶液初始pH为6～7时,电解180 min后的邻硝基苯酚的降解率可达95.1%.利用液相色谱和离子色谱检测了邻硝基苯酚电解产物,并初步分析了邻硝基苯酚的降解途径.     

电催化氧化处理变性木薯淀粉生产综合废水研究

采用DSA电极电催化处理变性木薯淀粉生产综合废水,研究了槽电压,电流密度,支持电解质,pH值,电解时间等因素对其中COD去除率的影响.在选定的实验条件下,槽电压8 V,电流密度为40 mA/cm2,支持电解质为0.1g/L的NaCl,pH值为8.5～9.0,电解2 h,废水中COD的去除率达88.3%.     

电芬顿法去除兰炭废水COD

为处理高浓度生物难降解兰炭废水,考查了利用不锈钢作阳极和石墨气体扩散电极作阴极构成的电芬顿体系对兰炭废水COD的去除效果。系统地考察了空气流速、电流密度、溶液pH值及极板间距等因素对废水COD去除率的影响。电解过程的较佳条件:空气流速为2.5 L/min;电流密度为5.2 mA/cm2;溶液pH值为3;极板间距为2 cm。电芬顿法处理兰炭废水240 min之后,COD最高去除率可达78.62%,实现了对兰炭废水的预处理,为兰炭废水的处理提供了新的途径。     

电催化氧化技术处理制革综合废水

选择DSA电极中的钛基掺硼金钢石膜电极(Ti/BDD),用于制革综合废水的电催化氧化处理研究,考察了在不同的电流密度、电压、电解质、pH值和电解时间等因素对COD去除率和电流效率的影响。结果表明,控制电流密度为30mA/cm2,电压为8.0 V,电解质(NaCl)浓度为2.0 g/L,pH为4.0,电催化氧化处理2 h后,废水的COD和NH4+-N的去除率分别达到了83.6%和90.3%,BOD/COD为0.45,比能耗为35.34 kWh/kg COD,电流效率为37%。     

电化学氧化法去除超高盐榨菜废水中的氨氮

采用电化学氧化法去除超高盐榨菜废水中的氨氮,阳极为Ti/RuO2-TiO2-IrO2-SnO2网状电极,阴极为网状钛电极,考察了电流密度、电解时间、极板间距、初始pH以及极水比对氨氮去除率的影响,并分析了电流密度对氨氮能耗和阳极效率的影响。结果表明,在初始氨氮浓度为472.73 mg/L,电流密度为156 mA/cm2,极板间距为1.5 cm,极水比为0.8dm2/L,原水pH为4.3～5.0时,电解30 min和60 min时氨氮的去除率分别为89.75%和99.94%,电解30 min时,氨氮能耗最低为96 kWh/kg,阳极效率最高为8.47 g/(h.m2.A)。     

三维电催化氧化技术处理草铵膦农药废水

选用石墨板作为三维电催化装置的阳极、不锈钢板作为阴极,以活性炭颗粒作为粒子电极进行反应,研究了三维电催化氧化技术处理草铵膦农药废水的效果;并考察了电流密度、极板间距、电解时间、初始浓度、pH值和粒子电极用量等因素对其处理效果的影响。实验结果表明,在废水初始浓度为300 mg·L~(-1),反应时间为90 min,极板间距为4 cm,pH值为5,电流密度为31.5 m A·cm-2,粒子电极的用量为3.08 g·L~(-1)的条件下,废水的COD去除率为83.48%。三维电催化氧化技术通过减小粒子间距改善电荷传质效果;电流效率的提高也促使废水的处理效果显著提升。     

钛基IrO2-SnO2电极在烟气海水脱硫恢复系统中的应用

采用浸渍-热分解法制备了含IrOx-TiO2中间层的IrO2-SnO2电极,得到的电极具有较高的析氯电催化活性和较强的稳定性,并通过电化学氧化法对Na2SO3海水脱硫模拟液进行处理,考察了电流密度、温度、pH值和电解时间等电解工艺参数对Na2SO3去除率和化学需氧量COD的影响.结果表明,在电流密度为200 mA/cm...     

RuO_2-IrO_2/Ti阳极电催化降解偶氮染料甲基橙模拟废水

以自制Ti基Ru O2-Ir O2镀层形稳电极为阳极,采用电催化氧化处理偶氮染料甲基橙模拟废水。以硫酸钠为支持电解质,在自然p H条件下分别考察了电解时间、电极间距、电流密度和电解质浓度等因素对甲基橙去除率的影响,并分析其原因。实验结果表明,在自然p H、电极间距为1.0 cm、电流密度为30.0 m A/cm2、电解质硫酸钠浓度为20.0 g/L、电解1.0h,甲基橙去除率高达90.0%以上。因此,电催化氧化法作为一种高效、简便的染料废水处理技术,具有一定的应用潜力。     

铁阳极电化学对直接大红4BE模拟废水脱色

对铁阳极电化学处理直接大红4BE染料废水脱色率和脱色能耗的影响因素进行研究。考察了电流密度、染料溶液初始pH值、染料初始浓度和支持电解质Na2SO4浓度对脱色性能的影响。结果表明,电流密度、染料废水初始pH、染料初始浓度、支持电解质浓度对脱色率和脱色能耗产生较大影响。在电流密度1.667 mA/cm2、pH值6.54、染料浓度50mg/L、Na2SO4浓度0.01 mol/L、温度20℃、搅拌速度600 r/min、电解时间60 min条件下,脱色率达到92.1%,脱色能耗1.298 kWh/kg染料、铁阳极消耗量41 mg/400 mL染料模拟废水。     

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.