吸收CO2新型混合化学吸收剂的研究

以吸收剂吸收速率和再生程度为指标,在小型实验装置台上研究了3种混合吸收剂不同配比的吸收和再生特性,以确定其吸收剂主体和添加剂的合适配比.结果表明,在甲基二乙醇胺(MDEA)中添加哌嗪(PZ),当混合吸收液CO2负荷为0.2 mol·mol-1时,MDEA∶PZ=1∶0.4(m∶m)混合液CO2吸收速率比MDEA∶PZ=1∶0.2(m∶m)混合液提高了约70%.再生40 min,PZ 相对浓度为0的吸收液再生程度为91.04%,PZ相对浓度为0.2、0.4和0.8时,混合吸收液的再生程度分别降低为83.06%、77.77%和76.67%.综合比较,MDEA∶PZ=1∶0.4(m∶m)是该混合吸收液合适的配比,吸收速率和再生特性都有较好改善.在10%一级胺中添加2%三级胺既能保持高吸收效率,又能略微降低再生能耗.在10%二乙醇胺(DEA)中加入2%2-氨基-2-甲基-1-丙醇(AMP),混合液表现出DEA/AMP混合吸收剂中较好的吸收和再生特性.3种配方中,在一级胺中添加少量三级胺吸收速率最高,二级胺和少量空间位阻胺混合吸收剂的再生性能最好.而综合吸收和再生2个指标,三级胺和中量活化剂的混合液有优势.     

不同有机胺溶液对SO_2脱除与再生性能的对比研究

采用鼓泡反应装置,测量了不同有机胺溶液对SO_2的脱除性能和再生能力。结果表明:二元胺吸收剂的循环负载量和富液再生能力明显高于一元胺吸收剂,二元胺吸收剂的再生能力排序为HEPNPZPZAEEAEDAMDEATEADMEA;柠檬酸能够有效提升有机胺吸收剂的再生能力,以哌嗪为主体吸收剂、柠檬酸为添加剂的有机胺溶液体系具有良好的脱硫性能,当柠檬酸/哌嗪的浓度配比(摩尔比)为0.6时,其脱硫率大于98%,富液再生率由47.2%提升至82.0%,循环负载量由0.85mol/mol提升至1.05mol/mol;吸收剂循环次数的增加,其脱硫率逐渐下降,硫酸根离子逐渐累积,且富液再生率略有下降,但基本保持不变,有机胺溶液的整体循环稳定性较好。有机胺吸收剂脱硫性能的下降与溶剂损耗及硫酸根离子的累积有关。     

碳酸钠与有机胺复合吸收剂吸收与解吸CO_2的实验研究

采用常压磁力搅拌吸收-解吸装置,将碳酸钠和MEA(乙醇胺)、DEA(二乙醇胺)、DETA(二乙烯三胺)、TETA(三乙烯四胺)4种有机胺分别按照一定比例复配,综合考虑复合吸收剂的CO2吸收速率、吸收量、解吸速率、解吸量、经济成本等多方面因素,筛选出在实验操作条件下最优的二氧化碳吸收剂。实验结果表明,最优的复合吸收剂为摩尔浓度比为0.8 mol/L∶0.2 mol/L的Na2CO3-DETA吸收剂,当吸收温度和解吸温度分别为313 K和373 K时,吸收量为16 640 m L/L,一次解吸率为69.47%,其CO2吸收解吸综合性能最佳。     

吸收CO2新型混合化学吸收剂的研究

以吸收剂吸收速率和再生程度为指标,在小型实验装置台上研究了3种混合吸收剂不同配比的吸收和再生特性,以确定其吸收剂主体和添加剂的合适配比.结果表明,在甲基二乙醇胺（MDEA）中添加哌嗪（PZ）,当混合吸收液CO₂负荷为0 .2 mol·mol^-1时,MDEA∶PZ=1∶0 .4（m∶m）混合液CO₂吸收速率比MDEA∶PZ=1∶0 .2（m∶m）混合液提高了约70％.再生40 min,PZ相对浓度为0的吸收液再生程度为91 .04％,PZ相对浓度为0 .2、0 .4和0 .8时,混合吸收液的再生程度分别降低为83 .06％、77 .77％和76 .67％.综合比较,MDEA∶PZ=1∶0 .4（m∶m）是该混合吸收液合适的配比,吸收速率和再生特性都有较好改善.在10％一级胺中添加2%三级胺既能保持高吸收效率,又能略微降低再生能耗.在10％二乙醇胺（DEA）中加入2％ 2-氨基-2-甲基-1-丙醇（AMP）,混合液表现出DEA/AMP混合吸收剂中较好的吸收和再生特性.3种配方中,在一级胺中添加少量三级胺吸收速率最高,二级胺和少量空间位阻胺混合吸收剂的再生性能最好.而综合吸收和再生2个指标,三级胺和中量活化剂的混合液有优势.     

自然型氨基酸及其钾盐的 CO2吸收和再生特性

在CO2吸收过程中,选择具有不挥发和不发生氧化降解特性的氨基酸盐吸收剂有助于降低吸收剂损失和减轻环境污染风险,故本研究以CO2吸收速率和再生速率为指标,对L-精氨酸和精氨酸钾（PA）吸收剂的CO2吸收性能和常压下热再生性能进行了实验分析,并研究了吸收剂质量分数、反应温度及吸收-再生循环次数对CO2吸收特性的影响,同时还与乙醇胺（MEA）、二乙醇胺（DEA）和三乙醇胺（TEA）进行了对比分析.结果表明,在实验的质量分数范围内,PA具有最高的CO2吸收速率和吸收能力,分别为24.5×10-3mol.（L.min）-1和1.99 mol.mol-1,比相同质量分数的MEA高2.1%和290.2%.温度影响结果表明,40℃时PA和MEA的CO2吸收速率均高于其他实验温度.相同再生条件下,PA的贫液CO2负荷要略高于MEA,但PA的再生程度可达72.8%,比MEA高19%.同时,3次＂吸收-再生＂循环之后,10%PA的CO2吸收能力仍可保持在1.03mol.mol-1,比10%MEA高255.2%.实验结果也表明,L-精氨酸具有较强的CO2吸收能力,其CO2吸收速率与同质量分数的DEA可比.     

N-(2-羟乙基)哌嗪/硫酸溶液吸收SO_2的性能研究

采用含有羟基支链的N-(2-羟乙基)哌嗪为脱硫剂,加入硫酸配制成吸收液,进行了模拟烟气中SO 2脱除性能和工艺条件的研究。结果表明:N-(2-羟乙基)哌嗪/硫酸溶液对SO 2有较大的吸收容量,在实验条件下最高脱硫率可达99.96%;决定脱硫率的主要因素是初始p H值、吸收剂浓度和反应温度;对于SO 2含量在0.05%~0.4%范围内的模拟烟气,控制吸收液初始p H值6~7,吸收剂浓度0.3 mol/L,温度40~50℃,N-(2-羟乙基)哌嗪/硫酸溶液具有优异的SO 2吸收和解吸性能,首次解吸率高达60.56%。     

单一与复合固体吸收剂去除低浓度CO_2的性能比较

低浓度放射性14CO_2废气,越来越受到人们的关注,基于酸碱中和反应原理的碳酸化技术具有高效、快速的优点,是解决这一问题的主要技术之一。NaOH、CaO和Na_2CO_3等常见吸收剂,在单独使用时存在着吸收能力不足、用量大等问题,本研究模拟低浓度放射性14CO_2气体,制备了NaOH-Na_2CO_3和CaO-Na_2CO_3复合吸收剂。结果表明,NaOH-Na_2CO_3具有最高的吸收性能(1639.06 mg/mol),相比单一吸收剂,复合吸收剂明显提高了对CO_2的吸收能力;复合吸收剂在吸收过程中,除了气体直接与吸收剂组分发生反应以外,Na_2CO_3与CO_2反应生成的NaHCO_3,与NaOH或Ca(OH)_2反应生成Na_2CO_3或CaCO_3,促进对CO_2的吸收反应。     

MDEA-TETA混合液捕集电厂烟气中CO2的实验研究

分别以MDEA溶液和MDEA-TETA混合液为吸收剂对电厂烟气中的CO_2进行捕集.在相同的实验条件下,研究了吸收时间、吸收液浓度配比和反应温度对CO_2吸收率的影响,并对两种吸收剂的吸收效果进行对比分析.结果表明:吸收效率随着温度的升高而下降,温度低于45℃时,混胺吸收剂MDEA-TETA的吸收效率受温度的影响显著,温度高于45℃时,单一吸收剂MDEA的活化性能大幅度增强.MDEA-TETA混合液中两种胺的配比为6∶1,反应温度在25~65℃内,反应时间在5~20 min内时CO_2的吸收效果较佳,吸收率达90%以上,不同配比的混胺吸收剂的吸收效果均优于MDEA的吸收效果.     

可再生胺类脱硫剂的选择研究

采用哌嗪等二元胺和二乙醇胺为吸收剂,对模拟烟气进行SO2的吸收解吸实验研究,筛选出性能优异的吸收剂,并考察添加剂H2 S O 4对其性能的影响。实验表明:可再生胺类吸收剂脱硫率可接近100%,二元胺吸收剂较醇胺的SO 2吸收量大、pH值随时间变化慢、首次解吸率高;羟乙基支链对胺类吸收剂的抗氧化能力、SO2吸收量和首次解吸率均有影响,环状二元胺比链状二元胺的抗氧化能力好、首次解吸率高;在N-(2-羟乙基)哌嗪溶液中添加硫酸构成N-(2-羟乙基)哌嗪/H 2S O 4脱硫体系后,脱硫率未受影响、SO2吸收量变小、首次解吸率显著提高,具有更好的循环使用性能。     

混合有机胺吸收烟道气中CO2的交互作用机理

 采用双搅拌釜吸收反应器,对一乙醇胺(MEA)和N-甲基二乙醇胺(MDEA)混合有机胺水溶液吸收模拟烟道气中CO₂进行机理研究.结果表明,此混胺体系吸收效果显著;比较实验测定和双膜简化理论计算的反应增强因子E值符合程度;建立能表征混合有机胺吸收CO₂时发生化学反应交互作用的机理模型,提出相关系数.对总胺浓度2.0mol/L,MEA初始浓度在0.3～0.5mol/L混胺溶液而言,可用吸收负荷L函数表示: = (L) = 0.12+0.35e^-L/0.026     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

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.     

Effect of sorbed and desorbed Zn(Ⅱ) on the growth of a green alga (Chlorella pyrenoidosa)

Toxic effect of Zn(Ⅱ) on a green alga (Chlorella pyrenoidasa) in the presence of sepiolite and kaolinite was investigated.The Zn-free clays were found to have a negative impact on the growth of C.pyrenoidosa in comparison with control samples (without adding any clay or Zn(Ⅱ)).When Zn(Ⅱ) was added,the algae in the presence of clays could be better survived than the control samples,which was actually caused by a decrease in Zn(Ⅱ) concentration in the solution owing to the adsorption of Zn(Ⅱ) on the clays.When the solution system was diluted,the growth of algae could be further inhibited as compared to that in a system which had the same initial Zn(Ⅱ) concentration as in the diluted system.This in fact resulted from desorption of Zn(Ⅱ) from the zinc-contaminated clays,although the effect varied according to the different desorption capabilities of sepiolite and kaolinite.Therefore the adsorption and desorption processes of Zn(Ⅱ) played an important part in its toxicity,and adsorption and desorption of pollutants on soils/sediments should be well considered in natural eco-environmental systems before their risk of toxicity to aquatic organisms was assessed objectively.