由硫酸亚铁(绿矾)制取还原铁粉的工艺研究

提出了一种新的绿矾综合利用的途径,即绿矾经碳酸盐转化,然后采用无烟煤作还原剂,CaCO3为添加剂,进行高温还原焙烧制取还原铁粉.先将绿矾用水溶解,用理论量1.2倍的(NH4)2CO3将FeSO4转化为FeCO3,FeCO3焙烧的最佳条件是FeCO3∶无烟煤∶CaCO3为100∶60∶8,焙烧温度为1000℃,焙烧时间为4.5 h.粗还原铁粉化学成分除C含量较高外,符合国家有关标准,900℃左右经氢气精还原1 h所得精还原铁粉化学成分的各项指标,均达到或优于国家有关标准的要求.     

还原焙烧-酸浸回收电镀污泥中的铜

采用还原焙烧—酸浸工艺处理电镀污泥,可以实现对铜的选择性回收.研究了不同焙烧条件下,电镀污泥的失重率和金属含量,并探索了焙烧温度、焙烧时间、煤粉用量、CaCO3投加量对金属浸出率的影响.结果表明,还原焙烧有利于污泥减量和金属富集;并且经还原焙烧污泥中金属的浸出效果明显优于直接焙烧;在电镀污泥中添加10％(质量分数)的煤...     

电镀污泥的还原焙烧-酸浸

将电镀污泥作为一种重要的重金属资源加以回收利用,逐渐成为了国内外研究的重点。以电镀污泥为研究对象,在不同的温度及不同的焙烧时间下进行直接焙烧和还原焙烧,并对焙烧底渣进行酸浸,分别研究了污泥减量率以及Cu、Ni、Zn和Cr 4种重金属的含量和浸出率,并探索了还原剂(煤粉)和催化剂(CaCO3)投加量的影响。实验结果表明,原始电镀污泥中,Cu含量最高,达到10.05%,因此,电镀污泥中Cu具有回收价值;焙烧后电镀污泥得到了减量化,同时污泥中的金属得到了富集;还原焙烧比直接焙烧更有利于Cu的选择性浸出,当煤粉投加量为10%,CaCO3投加量为0.5%,在700℃下焙烧20 min时,Cu的浸出率达到98.73%,Cu的含量达到15.07%。     

拜耳法赤泥还原焙烧工艺及产物性质分析

采用正交实验,考察焙烧温度、焙烧时间、还原剂和添加剂用量对拜耳法赤泥还原焙烧效果的影响。结果表明,在焙烧温度为1 080℃,焙烧时间为70min,赤泥、还原剂、添加剂质量比为100∶9∶7的最优条件下还原焙烧赤泥,经过磁选,赤泥中的含铁矿物得到富集,精矿品位平均为67.36%,回收率平均为85.54%。用热重(TG)/差示扫描量热(DSC)分析、扫描电子显微镜(SEM)分析、X射线衍射(XRD)分析以及质量磁化率测定等方法,对赤泥还原焙烧前后的理化特性进行研究,证实经过还原焙烧,赤泥中Fe_2O_3转化为Fe_3O_4和Fe。     

还原焙烧电镀污泥中的金属形态和浸出性

分别以煤粉和稻杆为还原剂对电镀污泥进行还原焙烧,并通过酸浸回收焙烧渣中的金属。研究了焙烧温度、焙烧时间和还原剂投加量对目标金属Cu浸出率的影响以及主要杂质金属的浸出性,并采用BCR逐级提取法分析了焙烧前后污泥中的金属形态分布。结果表明,当在电镀污泥中投加30％的煤粉在600℃下焙烧1h后Cu的浸出率达到97．78％,当投加50％的稻杆时浸出率为89．47％,而氧化焙烧后浸出率仅为37．71％;并且还原焙烧渣中多数杂质金属的浸出率较低,从而可以实现Cu与杂质金属的初步分离。氧化焙烧容易导致金属从易浸出的非残渣态向难浸出的残渣态转化,而还原焙烧则能抑制这种转化过程,金属形态是决定其浸出性的重要因素。     

零价铁对土壤中对氯硝基苯的还原作用

在常温常压下,利用零价铁(Fe0)还原土壤中的对氯硝基苯(p-CNB),研究反应产物随时间的变化以及反应条件对还原率的影响.实验结果表明,Fe0能够有效将土壤中的p-CNB还原成对氯苯胺(p-CAN),反应过程中先生成中间产物对氯亚硝基苯(p-CNSB),然后再进一步还原生成p-CAN.p-CNB还原率受到反应时间,土壤初始pH、温度、铁粉用量和土壤含水率等条件的影响.当p-CNB约为2.5×10-6mol/g,土壤初始pH为6.8,铁粉用量为50 mg,土壤含水率为75%时,在恒温生化培养箱中温度为(25±1)℃条件下,反应5 h后p-CNB还原率达到97.43%.     

硫酸盐还原菌落活性的研究

从广州某污水处理厂采取含硫酸盐还原菌（SRB）的污泥,经富集培养、驯化,研究该硫酸盐还原菌（SRB）在pH值为7．5、30℃的完全厌氧环境中,使硫酸盐转化的效率。试验证明,经过富集、驯化后的硫酸盐还原菌,在1～2h内生长最快,硫酸盐还原效率最高,经过3h左右,硫酸盐还原率可达到93．8％。     

土壤中零价铁还原3-氯硝基苯的作用

利用零价铁在常温常压下对土壤中的3-氯硝基苯的还原,对反应物和产物随时间的变化及反应的各个影响因素进行了研究。实验结果表明,零价铁能够有效地将3-氯硝基苯还原为3-氯苯胺,反应过程中没有检测到脱氯产物。其反应速率随铁粉用量、反应体系含水量的增加以及反应温度的升高而升高,随土壤初始pH值的升高而降低。在土壤中3-氯硝基苯含量约为2.5×10^-6 mol/g,铁粉使用量为25 mg/g,反应体系中含水量为0.75 mL/g,pH值为6.8时,在恒温生化培养箱(25±1)℃反应5 h后,3-氯硝基苯的还原率达到92.75％。     

土壤理化性质对Fe0还原硝基苯的影响

采用零价铁(Fe0)还原降解土壤中的硝基苯,考察土壤理化性质对还原效果的影响。结果显示,当2 g土壤中NB含量约为2.5 ×10-6mol/g,铁粉用量为50 mg,土壤含水量为75％时,控温25℃条件下反应1 h,硝基苯在松砂土和中壤土中的还原率分别可达到82.9％和91.1％。硝基苯在2种土壤中的还原率表现出中壤土...     

电镀污泥氨浸渣中铬的回收

以电镀污泥氨浸渣为研究对象,采用钠化氧化焙烧方法,实现了铬物相的转化和回收。钠化氧化焙烧过程以Na_2CO_3作为钠化剂,掺量为20%(质量分数),在750℃下焙烧2.5h,铬的转化效果最佳。X射线光电子能谱结果表明,钠化氧化焙烧实现了氨浸渣中铬由非水溶态Cr(OH)_3向水溶态Na_2CrO_4的有效转变。在室温条件下水浸,固液比1g∶10mL,浸出5min,铬浸出率可达到91.36%。热力学计算结果显示,Cr(OH)_3与O_2、Na_2CO_3反应的吉布斯自由能为负值,表明Cr(OH)_3易于生成Na_2CrO_4,Na_2CrO_4易溶于水,易于回收。     

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.