污泥衍生吸附剂对铅离子的吸附机理研究

研究了化学活化法热解制取污泥衍生吸附剂的工艺过程，得出相应工艺条件。利用污泥衍生吸附剂吸附溶液中重金属离子Pb^2＋，得到动力学模型。实验结果表明：（1）该吸附过程分为3个阶段：初始阶段（t≤20min）、过渡阶段（20min〈t≤30min）和后期阶段（t〉30min），满足线性方程dC／dt=kC；（2）该吸附过程的吸附活化能E=26，5kJ／mol，吸附频率因子A=6900s^-1。整个吸附过程为扩散吸附，吸附传质速度由孔隙扩散阶段和内表面吸附共同控制。     

黄粉虫粪基吸附剂的制备工艺优化及其吸附性能

黄粉虫养殖过程中,会产生大量的虫粪。用黄粉虫粪为原料制成吸附剂,并用于亚甲基蓝模拟废水的处理。研究在不同磷酸浓度W、浸泡时间t1、活化温度T、活化时间t2等制备因素影响下,吸附剂对亚甲基蓝的吸附能力。结果表明,黄粉虫粪吸附剂最佳制备条件为:W=25 wt%,t1=10 min,T=400℃,t2=50 min。此条件下制备的吸附剂的比表面积为(589.6±2.1)m~2·g~(-1)。该吸附剂对亚甲基蓝的吸附动力学符合Ho-Mc Kay模型,吸附速度控制步骤为内扩散,吸附等温线符合Langmuir模型,最大吸附量可达117.65 mg·g-1,吸附过程为热力学自发行为。     

硫酸活化市政污泥对亚甲基蓝的吸附

采用市政剩余污泥作为原料,以硫酸作为活化剂制备吸附剂,并将其应用到含亚甲基蓝废水处理中。系统地研究了溶液初始pH值、亚甲基蓝初始浓度和吸附时间等因素对硫酸活化市政污泥吸附性能的影响。研究结果表明,在吸附剂投加量2 g/L,pH7.5,温度293 K条件下,硫酸活化市政污泥对亚甲基蓝的最大吸附量为38.4794 mg/g。吸附动力学和热力学研究结果表明,吸附剂对亚甲基蓝的吸附过程可用准二级动力学模型(R2=0.9910)、Freundlich吸附等温式(R2=0.9935)来描述。颗粒内扩散速率也是其吸附反应限制因素,但不是惟一限制因素。该研究表明,硫酸活化剩余污泥可以作为含亚甲基蓝染料废水的处理材料。     

响应面分析法优化造纸污泥吸附剂除磷工艺

以造纸厂废水污泥为原料,采用微波加热法制备造纸污泥吸附剂。利用制备的造纸污泥吸附剂对模拟含磷废水进行了吸附研究,探讨了吸附时间、投加量、pH值、转速和温度等因素对除磷效果的影响,并采用响应面设计法优化吸附工艺条件。结果表明,获得了最佳除磷工艺条件为吸附时间97 min,投加量6.9 g/L,pH=6,转速200 r/min,温度30℃,在此条件下磷的去除率可达99%以上。因此,造纸污泥吸附剂对磷的吸附效果良好,具有重要的实际应用价值。     

藻类吸附剂对六价铬的吸附特性

以浮游藻类制成的生物吸附剂为对象,研究了不同液相起始pH、吸附剂用量Cm和不同吸附时间t等因素对生物吸附剂吸附Cr(Ⅵ)的影响,并进行了热力学分析和对吸附前后藻类吸附剂进行了FTIR分析。结果表明,最佳吸附条件为:在起始pH=1.0,吸附剂用量Cm=6.0 g/L,吸附时间t=180 min,吸附温度T=30℃时吸附效率达到了92.10%;藻类吸附剂对Cr(Ⅵ)的吸附能很好地符合Langmuir模型和Freundlich模型,在实验的温度范围内,ΔG0均为负值,说明实验条件下藻类吸附剂对Cr(Ⅵ)的吸附反应能够自发进行;红外图谱显示在1 261~1 537 cm-1和1 034~1 053 cm-1区域峰发生了明显变化,说明其为细胞上的多糖、蛋白质等成分更多地参与了对Cr(Ⅵ)的吸附过程。由此可见,利用中水里生长的藻类制成生物吸附剂,吸附Cr(Ⅵ)具有可行性,吸附速率较高,吸附平衡时间较快。     

剩余污泥对酸性大红G的吸附

以剩余污泥为吸附剂,研究其对模拟废水中酸性大红G的吸附条件及吸附机理。结果表明,剩余污泥对酸性大红G的吸附是一个快速过程,吸附时间可控制在30 min;其吸附过程同时受液膜扩散和颗粒内扩散的影响,可以用假二级动力学模型进行描述和预测;Freundlich方程可以较好地描述剩余污泥对酸性大红G的吸附行为。污泥未调pH时,对pH<2的溶液中酸性大红G的吸附性能良好;污泥pH为1时,对实验范围(pH<11)溶液中的酸性大红G均可有效吸附;污泥投加量增加,酸性大红G去除率升高,但污泥对酸性大红G的吸附量下降。     

废电池-污泥吸附剂的优化制备及对Cr(Ⅵ)的吸附特性

以污水处理厂污泥为原料、废电池电极材料和ZnCl2为活化剂,耦合活化制备废电池-污泥吸附剂。利用筛选实验设计中Plackett-Burman和响应曲面法中Box-Behnken实验联用得出优化条件,3次平行实验验证得到制备的最优吸附剂碘吸附值和得率平均分别为474mg/g、44.8%。Cr(Ⅵ)吸附表明,Langmuir吸附等温模型(R2=0.995 3)和准二级动力学模型(R2=0.999 8)更适合描述该最优吸附剂对Cr(Ⅵ)的吸附行为。     

碳氮共掺杂污泥基吸附剂去除水中Cr(Ⅵ)

以城市污水厂脱水污泥为原料,通过添加尿素等辅助材料碳化制备污泥基吸附剂。采用比表面积孔隙分布测定仪、扫描电镜(SEM)、X射线衍射仪(XRD)对吸附剂表面组成及其结构进行表征,对比研究了掺入添加剂前后碳化污泥吸附剂对Cr(Ⅵ)的吸附行为。结果表明,C/N共掺杂碳化污泥吸附剂对Cr(Ⅵ)的吸附性能较直接碳化污泥吸附剂明显提高,2种吸附剂的最佳吸附时间分别为2 h和4 h,p H是影响污泥基吸附剂吸附去除Cr(Ⅵ)的关键因素,其最适p H值均在1.0~2.5范围内。室温下C/N共掺杂污泥吸附剂吸附Cr(Ⅵ)符合Langmuir吸附模型,准二级动力学模型能很好地描述2种碳化污泥基吸附剂的吸附行为。热力学研究表明,C/N共掺杂污泥吸附剂对Cr(Ⅵ)的吸附是一个自发的吸热过程。     

银杏叶生物炭对亚甲基蓝的吸附特性

以银杏叶为原料,在700℃下热解制备银杏叶生物炭(GBBC),研究其对溶液中亚甲基蓝(MB)的吸附。考察了pH、吸附时间、GBBC投加量等对吸附结果的影响。实验结果表明:GBBC是一种很好的吸附剂,适用的pH范围宽(2~12),达到吸附平衡时间短(30min);在初始MB质量浓度为50mg/L、GBBC投加量为2.0g/L时,对溶液中MB的去除率达99.2%。吸附过程符合准一级动力学模型(R~2=0.982 9),颗粒内扩散模型拟合结果进一步表明GBBC对MB的吸附受表面吸附和颗粒内扩散共同主导。等温吸附模型拟合发现,Langmuir-Freundlich模型能很好地描述GBBC对MB的吸附行为(R~2=0.989 1)。可见,GBBC是一种去除废水中MB的高效吸附剂。     

污泥-烟煤基活性炭的制备及其对苯酚的吸附性能

以石化企业在污水处理过程中产生的干化剩余污泥为原料,大同烟煤作辅助添加料,采用化学活化法制备污泥-烟煤基活性炭,探讨了活化剂(ZnCl_2)用量、活化温度、活化时间等条件对所制备的活性炭性能的影响。以活性炭的碘吸附值为衡量指标,当污泥∶烟煤(质量比)=1∶1时获得制备污泥-烟煤活性炭的最佳工艺条件为:浸渍液为ZnCl_2∶原料(质量比)=2∶1,活化温度550℃,活化时间30 min,在该条件下制备的活性炭的碘吸附值为990 mg·g~(-1),比表面积为836m~2·g~(-1),产率为46.6%。同时,以苯酚为目标污染物,考察了所制备的污泥-烟煤基活性炭对苯酚的去除效果,结果表明:污泥-烟煤基活性炭投加量为2.0 g·L~(-1)时,4 h后达到吸附平衡,离子强度对吸附容量没有显著的影响,溶液pH在4~10范围内对苯酚有较好吸附,pH=6时苯酚吸附容量为138.9 mg·g~(-1)。与同类吸附剂相比,制备的污泥-烟煤基活性炭可高效吸附水溶液中的苯酚。     

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.