工业废渣基除磷材料的静态吸附研究

研究了高效除磷材料（EPRC）对磷素的吸附特性,考察了投加量、初始浓度、初始pH值、粒径等对EPRC吸附性能的影响,分析了不同条件下EPRC的吸附过程。结果表明,最佳投加量为3.5 g/250 mL时,去除率达91.07%,出水TP浓度为0.45 mg/L。随着粒径减小,EPRC对磷素的吸附量增大,吸附平衡时间缩短。溶液初始pH值在碱性条件下,吸附容量变大。     

水枝锦活性炭对孔雀石绿的吸附性能研究

以水枝锦为原料,采用磷酸活化法制备成水枝锦活性炭,通过静态实验研究其对孔雀石绿的吸附性能.考察了水枝锦活性炭投加量、接触时间、pH和孔雀石绿初始浓度对孔雀石绿吸附效果的影响.结果表明,在温度为723 K、活化时间为1 h条件下,水枝锦活性炭得率为36.7%,比表面积为1 223m2/g;在298K、孔雀石绿初始质量浓度为250mg/L、接触270min条件下,水枝锦活性炭的最佳投加量为0.5 g/L,适宜pH为7～12;吸附量随温度的升高而增大,提高温度有利于吸附的进行;水枝锦活性炭静态吸附孔雀石绿的动力学行为符合伪二级动力学方程.静态吸附动力学研究为投加粉状活性炭的吸附池的设计和污水处理装置的运行提供基础信息,对于去除水中孔雀石绿技术的应用具有重要的实际意义.     

生物膜细菌藻酸盐对Cu2+的吸附动力学研究

以生物膜中提取的细菌藻酸盐为原料制备藻酸钙为吸附剂,对水溶液中的Cu2+进行了吸附动力学研究.试验结果表明,吸附时间、溶液初始pH和吸附剂投加量对藻酸钙吸附Cu2+影响显著.当溶液初始pH为4.0、Cu2+初始质量浓度为100 mg/L、吸附剂投加量为0.7 g/L时,藻酸钙对Cu2+的平衡吸附量为56.15 mg/g.水溶液中Cu2+在藻酸钙上的吸附动力学过程可用准二级动力学方程来模拟.吸附等温线研究表明,藻酸钙吸附Cu2+的过程可用Langmuir和Freundlich模型来描述.100 mmol/L 乙二胺四乙酸(EDTA)可有效解吸95.6%的Cu2+,实现Cu2+的回收与吸附剂的重复利用.     

鸡蛋壳废料对水体中Cr(Ⅵ)的吸附特征与机理

利用鸡蛋壳废料对水中的Cr(Ⅵ)进行吸附处理,研究溶液p H、振荡时间、投加量和温度对鸡蛋壳废料吸附水体中Cr(Ⅵ)的特征和吸附机理。结果表明,在含有1 mg/L的Cr(Ⅵ)溶液的100 m L吸附体系中,鸡蛋壳废料可在30 min内完成吸附过程。溶液p H=2.5时,吸附量最大。鸡蛋壳投加量为1.0 g时,平衡吸附容量为0.0917 mg/g。利用鸡蛋壳去除水中Cr(Ⅵ)的最佳工艺参数为振荡时间30 min,初始p H为3.0,投加量2.0 g,体系温度35℃。鸡蛋壳对Cr(Ⅵ)的吸附过程用Langmiur和Freundlich方程能较好拟合,其中理论饱和吸附量在20℃、30℃和40℃时分别为0.1944、0.2034和0.2096 mg/g。吸附的焓变为8.76×10-3k J/mol,熵变为-45.96 J/(mol·K),吉布斯自由能变均为正值,变化范围是4.357~9.693 k J/mol。鸡蛋壳对Cr(Ⅵ)的吸附过程主要为物理性的单分子层和多分子层吸附。     

松树锯末对亚甲基蓝（MB）的吸附研究

采用松树锯末以及改性松树锯末对模拟废水中的亚甲基蓝进行吸附实验研究。研究结果表明,当亚甲基蓝的初始浓度为50 mg/L、pH为6、锯末投加量为1 g/L时,改性前后的锯末对亚甲基蓝的吸附量最大,分别为29.9 mg/g和60.6 mg/g。同时,对改性前后的锯末做了吸附等温线拟合及动力学研究。结果表明,吸附等温线均能很好地符合Langmuir吸附模式,吸附过程符合拟二级动力学方程。     

改性ZSM-5介孔沸石分子筛对焦化尾水吸附行为及动力学

通过改性制备了具有二次介孔的沸石分子筛(ZSM-5m),使用SEM、N2吸附-脱附等温线和XRD对材料的结构进行了表征。以焦化尾水残余有机污染物(ROPs)为研究对象,探讨ZSM-5m对ROPs的吸附行为和动力学。结果表明,溶液初始p H和吸附剂投加量对吸附效率均有一定的影响,ZSM-5m吸附量明显高于ZSM-5。在初始COD为150~350 mg/L,p H为3.0,投加量为2.0 g/L,吸附300 min后,ZSM-5m对COD去除率达到57.5%~69.7%,吸附量达到14.9~25.1 mg/g。吸附动力学拟合结果显示,可以更好地用假二级动力学方程和Elovich模型来描述;动边界模型推算表明,吸附的主要速度控制步骤为颗粒内扩散,温度升高,颗粒扩散控制作用减弱,表观活化能为12.58 k J/mol。推测ZSM-5m对ROPs的吸附是非均相扩散为主,带有复杂转化的物理吸附和化学吸附过程。     

磷在磁铁矿-针铁矿混合相上的吸附

首次采用使用后贴式取暖物（商业名：热力贴）为原料制备吸附剂,元素分析、XRD、红外图谱综合鉴定为磁铁矿-针铁矿混合相（magnetite-goethite mix phase,MGM）,其比表面积为98.3 m2/g,平均粒径为510 nm,零电荷点在pH=5.7附近;磷在MGM上的吸附等温线符合Langmuir方程,其吸附历时曲线遵循准二级动力学模型,升温能促进磷的吸附;在实际废水磷浓度为51.8 mg/L、初始溶液pH=2的条件下,当MGM投加量为10 g/L时,磷的去除率为94.16%。     

氢氧化钾改性亚麻对亚甲基蓝的吸附性能研究

以亚麻为原料,氢氧化钾为改性剂,制备了一种吸附剂,用红外光谱和扫描电子显微镜对其结构进行表征,并对其吸附亚甲基蓝的性能进行了研究。结果表明,经120℃、0.8mol/L氢氧化钾改性的亚麻对亚甲基蓝的吸附量和去除率明显提高。经优化,当pH=5、超声功率为50%(125W)、超声时间为25min、亚甲基蓝初始质量浓度为300mg/L、改性亚麻投加量为0.3g时,亚甲基蓝的去除率为95.1%,吸附量为28.54mg/g。其中,pH=5~9、亚甲基蓝初始质量浓度为300~500mg/L时,亚甲基蓝的去除率和吸附量变化不大。改性亚麻对亚甲基蓝的吸附过程符合Freundlich吸附等温式,其动力学过程符合准二级动力学方程。     

煤质炭制备条件的优化及对酚类吸附性能与吸附动力学

KOH为活化剂,正交实验方法优化了煤质炭的制备条件。对2种酚类有机物苯酚、氯苯酚进行了静态吸附,观察了温度、时间、初始浓度及投加量对吸附性能的影响,优化了吸附条件。实验数据与Langmuir、Freundlich和Temkin吸附等温线进行了拟合,并对准一级、准二级动力学模型和内扩散模型拟合。结果表明,优化得煤质炭制备条件为:碱碳质量比3∶1,浸泡时间12 h,活化时间80 min,活化温度800℃。在温度为25℃,投加量为0.05 g时,苯酚的平衡时间为60 min,初始浓度为200 mg/L时的吸附量为58.89 mg/g;氯苯酚的吸附平衡时间为90 min,初始浓度为300 mg/L时的吸附量为84.32 mg/g。煤质炭对苯酚的吸附过程与Langmuir吸附等温线,氯苯酚的吸附过程与Temkin吸附等温线拟合得较好。二级动力学模型能够较好地描述这2个吸附过程,且颗粒内扩散不是唯一的速率控制步骤。     

TiO_2@碳纳米管吸附去除盐酸四环素

采用静电组装法制备了Ti O2@碳纳米管复合吸附剂,用以除去水中的盐酸四环素。通过FE-SEM、EDS和XRD进行表征,考察了pH、初始浓度和吸附剂用量对吸附过程的影响,研究了吸附动力学、等温模型和热力学,并对吸附剂的再生进行了评价。结果表明,复合吸附剂对盐酸四环素的最大饱和吸附量为52.33 mg/g;最佳吸附pH值为6,强酸不利于吸附;当初始浓度在15~60 mg/L范围内时,吸附量随着初始浓度的增大而增加;当吸附剂投加量为0.50 g/L时,吸附效率最高。吸附过程符合准二级动力学模型和Langmuir等温模型。热力学参数ΔG0、ΔH0,表明该吸附过程是自发、吸热过程。H2O2-Ti O2光催化协同效应可有效完成吸附剂的再生。     

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.     

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.     

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 in deer and elk from Los Alamos national laboratory and the doses to humans from the ingestion of muscle and bone

Abstract

This paper summarizes radionuclide concentrations (³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, and ^totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y^‐1 (2.2 μSv y^‐1), deer bone = 3.8 mrem y^‐1 (38 μSv y^‐1), elk muscle = 0.12 mrem y^‐1 (1.2 μSv y^‐1), and elk bone = 1.7 mrem y^‐1 (17 μSv y^‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y^‐1 (1000 μSv y^‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04.     

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.