有机钙高温脱硫特性

为了控制燃煤二氧化硫气体的排放,采用智能定硫仪研究了有机钙的脱硫特性.原煤的硫析出速率曲线呈双峰形状,添加有机钙后,硫析出速率明显降低,曲线呈单峰状.1000℃下有机钙对长广煤的脱硫率比普通石灰石高1倍以上,其中醋酸钙镁的脱硫效果高达73.84%.煤的含硫量、反应温度、钙硫比、钙基添加剂粒径是影响有机钙脱硫效果的重要因素.煤的含硫量增大或钙基添加剂粒径减小都可以提高有机钙的脱硫率;随温度升高,高硫煤脱硫率下降幅度低于中硫煤和低硫煤,1 200℃高温下醋酸钙镁脱硫率为59.08%;按钙硫比为1添加有机钙可以获得较高的脱硫率,继续增加钙基添加剂,脱硫率的提高效果不明显.表明有机钙是一种脱硫效率较高的优良吸收剂,醋酸钙镁的脱硫效果最好.     

氯化钙在型煤燃烧过程中固硫作用的研究

当高硫煤中加入钙基主固硫剂，然后加入适量的CaCl2及其它添加剂，燃煤固硫率明显提高。本文用X-射线荧光光谱法对灰渣样品进行分析，讨论了添加剂对固硫率的影响，并就其促进固硫作用的机理作了初步探讨。     

无烟煤脱硫特性试验研究

以石灰石为脱硫剂,对晋城高硫无烟煤的脱硫特性进行了试验研究．定性分析不同温度和钙硫摩尔比条件下,高硫无烟煤中硫的析出特性;给出不同条件下的脱硫率和钙利用率,确定了晋城无烟煤的最佳脱硫温度和钙硫摩尔比;并同长广高硫烟煤的析出特性和脱硫率进行了比较,发现晋城高硫无烟煤析出的硫份主要是低温段析出的,高温段析出的硫份基本上被脱硫剂脱除;在相同条件下,无烟煤的硫份先于长广烟煤析出,脱硫效果相对较差．     

煤燃烧中硅酸盐A的高温固硫促进作用

研究了硅酸盐Ａ在不同含量，不同温度下的对碳酸钙固硫碱性能的影响，发现在１２００℃高温下，碳酸钙固硫剂中添加一定量的硅酸盐Ａ，固硫率从１６％提高到３３％，提高率达１０６％，若添加碳酸钾与硅酸盐Ａ的复合添加剂，则固硫率为３６％，提高率为１２５％，用含硅酸盐Ａ的钙基固硫剂与煤制成型煤，在实际锅炉中于１２５０℃试烧，其固硫率达４７％。     

添加剂CeO_2对煤粉燃烧中钙基固硫的影响

针对内蒙古某火电厂用煤,以CaCO3为固硫剂,CeO2为固硫添加剂,进行了箱式电阻炉定温固硫实验,分析了温度、钙硫比、添加剂CeO2对燃煤固硫率的影响;热重法分析了固硫添加剂CeO2对煤炭燃烧性能的影响。结果表明:加入CeO2低温下(850℃、950℃)促进了燃煤固硫,提高了燃煤固硫率,而在高温下(1 050℃),催化作用导致固硫剂表面孔隙迅速堵塞,降低产物层扩散控制阶段反应速率,抑制了固硫过程的进行;CeO2催化了煤炭挥发份和固定碳的燃烧,降低了固硫煤着火点温度和燃尽温度,改善了煤的燃烧性能;揭示了添加剂CeO2催化固硫和催化燃烧的作用机理。     

煤矸石砖烧结固硫的实验研究

在煤矸石制砖原料中添加高效固硫剂,可显著降低砖瓦焙烧过程中废气SO_2产生量,实现从源头减少SO_2排放的目的,并降低末端脱硫成本。文章通过对CaO、CaCO_3、Ca(OH)_2 3种钙基固硫剂在不同添加量下的固硫效果以及对烧结砖强度的影响分析发现,随着添加量的增加,3种固硫剂的固硫率逐渐增加,在钙硫比为1.0时,固硫率最高可达到47.74%;在添加量相同时,添加Ca(OH)_2的烧结砖强度要大于添加CaCO_3和CaO的烧结砖强度。通过优化配比,研究了Ca(OH)_2和CaCO_3 2种固硫剂按7∶3的比例混合制备复合钙基固硫剂,当钙硫比为0.8时,复合固硫剂的固硫率为47.79%,增加了11.96%,而复合固硫剂对烧结砖抗压强度的影响与Ca(OH)_2类似。研究结果可为煤矸石砖固硫剂制备提供支持。     

高硫煤炉内燃烧脱硫的试验研究

采用正交实验的方法对济源高硫煤炉内燃烧脱硫进行了实验研究,确定了影响固硫率的主要因素,研制出了适于济源高硫煤炉内燃烧脱硫的固硫剂,并进行了工业性试验。结果表明,通过添加固硫剂可有效地减少燃煤过程中SO2的排放,对于以有机硫为主的济源高硫煤,炉内燃烧脱硫是一种行之有效的脱硫方法。     

DCL型燃煤固硫剂固硫技术在广州石化热电站的应用

随着环保要求的日趋严格，燃煤锅炉的脱硫已势在必行，DCL型燃煤固硫剂脱硫技术是中科院“九五攻关”项目之一，其技术原理是通过添加助剂提高固硫剂的吸附表面及其活性，同时将SO2转化为SO3或使MeSO3转化为MeSO4，从而使CaO固硫率大大提高，本文介绍了DCL型燃煤固硫的技术特点，因硫原理，固硫工艺和固硫设备及其在广州石化热电站的应用效果，通过运行数据分析和成本比较，证实DCL固硫剂固硫技术的适用性。     

铁硅系添加剂对型煤燃烧时硫行为的影响

利用扫描电镜（ＳＥＭ）、能谱分析（ＥＤＡＸ）和Ｘ射线衍射分析等现代物理分析技术，从形态、化学组成和结构三方面入手，研究了型煤燃烧时，添加铁、硅、锶等以钙为主的几种固硫剂后，灰渣的物相变化及硫的走向，结果表明，钙系化合物的型煤燃烧时，煤中的硫以硫酸钙的形式进入渣中，硫酸钙被高融点硅酸盐矿物所包裹是高温下硫酸钙不易分解的重要原因，添加少量碳酸锶的钙系固硫剂，硫元素除了形成硫酸钼和硫酸锶以外，还形成了一     

以CaS为燃煤固硫产物的热力学可行性和实验探索

高于１２００℃的燃煤固硫因ＣａＳＯ４的分解而因硫效率不高。ＣａＳ在高温下不会分解，若以ＣａＳ形式能将硫分固定下来，可以大大提高固硫效率。从热力学研究着手，计算预测了以ＣａＳ形式固硫的可行性；在富煤还原气氛燃烧时，在高于１２２７℃可达９０％的固硫效果；在贫煤燃烧时，由于局部存在还原气氛，也可达到一定的固硫效果。本文实验表明，固硫剂中的某些非钙基添加剂可以在高温下形成玻璃态物质，更好地抑制ＣａＳ的氧化     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.