磁性埃洛石复合材料的制备及其对十八烷胺吸附性能研究

采用共沉淀法制备磁性埃洛石复合材料,并对其吸附十八烷胺的行为进行研究.利用红外光谱(FT-IR)、透射电子显微电镜(TEM)和振动样品磁强计(VSM)对磁性埃洛石进行表征,研究吸附剂浓度、吸附时间、溶液p H值和温度对十八烷胺在磁性埃洛石上吸附的影响,采用Lagrange准二级动力学方程、Langmuir等温线方程及Freundlich等温线方程对实验数据进行拟合.结果表明:Fe3O4纳米粒子成功的负载到埃洛石的表面;p H值和温度对十八烷胺在磁性埃洛石上的吸附影响较大;十八烷胺在磁性埃洛石上的吸附符合二级动力学模型;热力学符合Langmuir等温线方程,并且高温利于十八烷胺的吸附.     

Co(Ⅱ)在磁性埃洛石上的吸附行为研究

采用化学共沉淀法成功制备了磁性埃洛石,运用扫描电子显微镜(SEM)、红外光谱仪(FT-IR)、X射线衍射仪(XRD)和振动样品磁强计(VSM)等手段详细表征了改性前后埃洛石的结构和形态,并采用静态批量平衡法对Co(Ⅱ)在磁性埃洛石上的吸附行为和机理进行探究,考察了料液比、平衡时间、p H值和温度等因素对吸附的影响.实验结果表明:温度为50℃时,Co(Ⅱ)在磁性埃洛石上的最大吸附容量为17.5mg·g-1.p H7.5时,随着p H增加,吸附量增大;当p H=7.5时,吸附量达到最大;以后即使p H增大,吸附量也不会明显变化.动力学过程符合准二级动力学方程;热力学过程符合Langmuir吸附等温线;升高温度利于Co(Ⅱ)在磁性埃洛石上吸附.     

铝改性粉煤灰漂珠吸附水溶液中砷的性能研究

采用湿法与干法相结合的方法合成铝改性粉煤灰漂珠环境材料,借助静态吸附实验研究吸附剂量、pH值、离子强度、共存离子、反应时间和温度对其吸附水溶液中砷性能的影响,并进行吸附等温线和动力学拟合.结果表明:铝改性粉煤灰漂珠吸附水中As(V)的最佳pH值范围为中性偏酸;混合离子和H2PO4-对As(V)的吸附影响较大,CO32-次之;离子强度对As(V)吸附的影响不明显;在温度298K、吸附剂量2.5g/L和反应时间24h的条件下,最大吸附容量约5000μg/g;吸附等温线符合Langmuir单层吸附模型;动力学过程符合准二级动力学模型.     

生物质炭对孔雀石绿和酸性橙的吸附研究

文章以生物质炭为吸附剂,研究了其对以孔雀石绿和酸性橙Ⅱ两种染料作为水污染物时的吸附行为,并且探讨了初始浓度、温度、离子强度及溶液p H值等因素对吸附效果的影响。结果表明吸附符合准二级动力学方程;离子强度对吸附效果贡献不大;随着p H值的增加,生物质炭对孔雀石绿的吸附量增加,而对酸性橙Ⅱ的吸附量降低;吸附热力学研究表明,吸附过程为自发的吸热反应,用Langmuir方程能够更好地对吸附等温线进行拟合。     

针铁矿对废水中Cr(Ⅵ)的吸附

该实验研究了针铁矿(α-Fe OOH)对废水中Cr(Ⅵ)吸附的影响因素、吸附等温线和吸附动力学。探讨在不同初始浓度、p H、吸附剂的量、离子强度条件下针铁矿对Cr(Ⅵ)的吸附特性。结果表明,针铁矿的吸附平衡时间为30 min;p H为3时,针铁矿对Cr(Ⅵ)的吸附效率最高;Cr(Ⅵ)浓度为15 mg/L时,最佳针铁矿投加量为2 g/L;Cr(Ⅵ)的吸附量随离子强度的升高而降低;温度升高,Cr(Ⅵ)的吸附量随之升高。分别用Langmuir、Freundlich和Temkin等温模型对不同条件下针铁矿吸附Cr(Ⅵ)的实验结果进行模拟,结果表明用Freundlich方程的拟合效果最佳,在35℃时相关性达到了0.995 2。针铁矿吸附Cr(Ⅵ)的吸附动力学满足准二级动力学方程,吸附表观活化能Ea=31.306 k J/mol。实验结果表明,针铁矿在废水除铬(Ⅵ)领域有实际应用的潜力。     

羟基铁覆膜膨润土对砷的吸附性能研究

本研究用Fe(NO3)3·9H2O和NaOH合成羟基铁并对膨润土进行覆膜。探索最宜覆膜方式,并考察吸附剂投加量与pH值对覆膜膨润土吸附砷的影响,并采用Langmuir、Freundlich吸附等温线模型和准一级动力学模型、准二级动力学模型对实验数据进行拟合。结果表明:当铁碱比为1∶2时以及水样pH=4.5时,吸附效果最佳;覆膜膨润土对砷的吸附符合Freundlich方程和准二级动力学模型,最大吸附量为40.69 mg/g,存在明显的化学吸附。     

磁性微藻复合物的制备及其对铀的吸附性能研究

通过水热法对冷冻干燥得到的雨生红球藻粉(PRCP)进行改性,合成了磁性γ-Fe₂O₃/PRCP,并采用X-射线衍射仪(XRD)、扫描电镜(SEM)、傅里叶变换红外光谱仪(FT-IR)、X-射线光电子能谱(XPS)、X射线能谱分析(EDS)、BET等方法对材料的形貌和结构进行了表征,通过静态吸附实验分别探究了不同pH值、初始铀浓度、温度、时间等对铀酰离子吸附性能的影响.结果表明,在初始pH=6时,材料对铀的吸附效果最好.从吸附动力学看,吸附过程更符合准二级动力学模型.通过对材料进行热力学模型拟合发现,在25℃、pH=6时材料吸附过程更符合Langmuir方程,且随着溶液中初始铀酰离子浓度的升高,材料表现出了更好的吸附效果.     

铝改性粉煤灰漂珠材料吸附水中氟的性能研究

采用湿法+干法制备铝改性漂珠材料,借助静态吸附实验研究吸附剂用量、pH值、共存离子、反应时间和反应温度对去除水溶液中氟离子性能的影响,并对实验数据进行吸附等温线和动力学拟合。结果表明:铝改性漂珠材料吸附水中氟离子的最佳pH值为3;最佳吸附剂用量2.5 g/L;共存离子影响由强到弱的顺序为H2PO4-,SO42-和NO3-的混合物﹥H2PO4-﹥SO42-﹥NO3-;在温度298 K、吸附剂用量2.5 g/L、pH值为3和反应时间24 h的条件下,最大吸附容量约10.2 mg/g;吸附等温线符合Langmuir单层吸附模型;动力学过程符合准二级动力学模型。     

改性底泥吸附模拟废水中Mn~(2+)影响因素的研究

制备高温焙烧改性底泥作为吸附剂,采用静态吸附试验来研究其吸附废水中重金属Mn~(2+)的效果。分别对高温焙烧改性底泥吸附重金属Mn~(2+)的影响因素(Mn~(2+)的质量浓度、吸附时间、p H、吸附剂的投加量)及吸附动力学进行研究。结果表明:改性底泥吸附Mn~(2+)的浓度为10 mg/L、平衡时间为130 min、p H为中性偏酸(范围4~7)、投加量为30 g/L时效果最佳,并对数据进行拟合且符合Langmuir和Freundlich吸附等温方程,但拟合效果更好地符合Freundlich吸附等温方程。在高温焙烧改性底泥对Mn~(2+)的吸附阶段用伪一级吸附动力学方程和伪二级吸附动力学方程进行拟合,其结果表明吸附过程更好地遵循伪二级吸附动力学方程,表明以化学吸附为主,对Mn~(2+)的平衡吸附量为11.560 7 mg/g。     

碳纳米管-羟磷灰石对铅的吸附特性研究

采用多壁碳纳米管-羟磷灰石(MWCNT-HAP)复合材料,通过间歇试验研究了MWCNT-HAP对Pb(Ⅱ)的吸附特性.主要探讨了固液比、p H、离子强度、反应时间、Pb(Ⅱ)的初始质量浓度及温度等因素对吸附的影响.结果表明,固液比、p H与温度对于去除Pb(Ⅱ)的影响较大,离子强度影响较小.当温度为20℃,固液比为0.08 g·L-1,p H0为5.5,Pb(Ⅱ)的初始质量浓度为100 mg·L-1时,吸附量为716.13 mg·g-1.动力学试验结果表明,MWCNT-HAP吸附Pb(Ⅱ)为快速反应过程,在30 min时,吸附量可达最大吸附量的90%,60 min即可达平衡.伪二级动力学模型可较好地拟合动力学试验数据,可采用该模型描述MWCNT-HAP对Pb(Ⅱ)吸附的动力学过程.热力学试验结果表明,在不同温度下的自由能变均为负值,表明MWCNT-HAP对Pb(Ⅱ)的吸附为自发反应,升温有利于反应进行.Langmuir模型拟合不同温度下的等温试验结果得到可决定系数(R2为0.999 8~1.000 0),可采用该模型模拟MWCNT-HAP对Pb(Ⅱ)的等温吸附过程.MWCNT-HAP去除Pb(Ⅱ)的主要机制为MWCNT-HAP表面含氧官能团与Pb2+间的络合反应、HAP的分解-沉淀、Pb2+与Ca2+离子交换等.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.