羊粪生物炭对水体氨氮吸附特性研究

以山羊粪便为原料,在300℃和700℃缺氧热解条件下制备生物炭,分别记为D300和D700。使用扫描电镜表征生物炭结构特征,运用比表面积仪测定其比表面积和孔径大小,以此探究不同热解温度条件下羊粪生物炭的内部结构及比表面积特征。以水体氨氮(20 mol/L)为目标污染物,以D300和D700为吸附剂,研究不同氨氮浓度、温度、pH以及吸附剂投加量等因素对水体氨氮吸附的影响以及吸附特性。结果表明:热解温度从300℃上升到700℃,生物炭的比表面积、总孔容随之增大,平均孔径反之减小,吸附效率从15.72%提升到24.73%。羊粪生物炭吸附水体氨氮的最佳pH在6～8;通过对动力学数据进行分析,发现准二级动力学方程(R~2=0.999 1)比准一级动力学方程(R~2=0.663 3)能更好地拟合动力学数据。吸附等温曲线拟合发现Langmuir方程(R~2=0.842 74)能更好地描述氨氮在羊粪生物炭上的吸附行为。吉布斯自由能变化、焓变和熵变的计算结果表明:羊粪生物炭对氨氮的吸附过程是自发的吸热过程。700℃条件下制备的羊粪生物炭比D300拥有更好的吸附性能。     

改性芦苇生物炭对水中低浓度磷的吸附特征

为吸附处理低浓度含磷废水和实现芦苇资源化利用,将湿地植物芦苇制备成生物炭,通过负载氯化铁进行改性,探究了改性芦苇生物炭对水体中磷的吸附特征.结果表明,改性后芦苇生物炭的含铁量为11.98 mg·g~(-1),是改性前的44.7倍;改性芦苇生物炭p H_(pzc)为7.49,当溶液p H为7.0时,吸附效果最好;在磷溶液浓度为4.0 mg·L~(-1)、温度为298K时,改性芦苇生物炭平衡吸附量为0.658 mg·g~(-1),是未改性生物炭吸附量的34.6倍.研究不同温度下的吸附等温线,Langmiur方程很好地拟合不同温度的吸附等温线,该吸附是单层吸附,温度升高有利于吸附.吸附热力学研究表明,ΔG~θ0、ΔH~θ0和ΔS~θ0,说明该吸附是自发、熵增的吸热过程.假二级方程很好地拟合改性芦苇生物炭吸附磷的动力学数据,初始吸附速率随初始浓度的增大而增大,该吸附主要受颗粒内扩散控制.该研究为改性芦苇生物炭用于污水处理厂和水体深度除磷提供基础数据.     

生物炭结构性质对氨氮的吸附特性影响

氨抑制现象在富含有机氮底物的沼气工程中普遍存在,采用生物炭吸附法可固定发酵液中氨氮.为探究生物炭理化结构与氨氮吸附特性之间的相关关系,在不同热解温度(350、450和550℃)下制备以玉米秸秆、稻壳为原料的生物炭,通过元素分析、FTIR和BET等分析生物炭结构及其理化性质,并结合批式吸附实验,研究不同理化性质生物炭对氨氮的吸附特性影响.结果表明随着热解温度的升高,生物炭中碳及灰分含量增多; 450℃制备的玉米秸秆生物炭(CS450)与550℃制备的稻壳生物炭(RH550)对氨氮的吸附分别遵循准二级和准一级动力学模型.Freundlich吸附模型能更好地描述CS450和RH550生物炭对氨氮的等温吸附过程;玉米秸秆炭吸附量与其表面官能团间具有显著相关性;而与稻壳炭的吸附量相关性最显著的为生物炭的比表面积,其次是表面官能团,最后是灰分.其中,RH550吸附性能最好,最大吸附量为12. 16 mg·g~(-1).     

不同热解及来源生物炭对西北黄土吸附敌草隆的影响

以西北黄土为研究对象,采用批量法研究不同温度下制得的生物炭对西北黄土吸附敌草隆的影响.结果表明,敌草隆在添加不同质生物炭黄土上的动力学吸附过程较好地符合准二级吸附动力学模型,且吸附过程主要分为快吸附(0~8 h)和慢吸附(8~12 h)两个阶段,在12 h左右达到平衡;热力学较好地符合Freundlich等温吸附模型;添加生物炭的黄土对敌草隆的吸附量随着温度的升高而增大,且吸附过程中ΔG~θ小于0,ΔH~θ和ΔS~θ大于0;不加生物炭的黄土对敌草隆吸附量则随着温度的升高而降低,且吸附过程中ΔG~θ和ΔH~θ小于0,ΔS~θ大于0;在体系温度范围内,E(吸附平均自由能)为1.29~5.00 k J·mol-1,表明无论是否添加生物炭,黄土对敌草隆的吸附都以物理吸附为主.其影响因素分析结果显示,随着生物炭热解温度的升高,溶液中敌草隆的平衡浓度降低,平衡吸附量增大;添加生物炭的黄土对敌草隆吸附量在0.5~6 mg·L-1浓度范围内快速上升,之后吸附量随初始浓度的升高缓慢增加并逐渐趋于平衡;溶液pH对黄土吸附敌草隆有一定影响,但影响不大.     

热解温度和时间对生物炭pH值的影响

以稻草、玉米秸秆、木屑、鸡粪为实验原料,分别在不同热解温度(250℃、300℃、350℃、450℃、650℃)和热解时间条件下(30 min、60 min、90 min、120 min、180 min)制备出生物炭。并在不同生物炭与水的质量比条件下,依据正交实验设计的方案,依次测定了各种生物炭的pH值。结果表明,热解温度是影响各种生物炭pH测定值的关键性因素,生物炭与水的质量比也对pH测定值产生一定的影响,而热解时间的长短并未对生物炭pH测定值产生显著影响。在250~650℃的热解温度条件下,随着温度的升高,四种生物炭的pH值均有不同程度的升高,尤其是在250~350℃这一温度区间,四种生物炭的pH值升高速率最快,此后,随着热解温度的升高,生物炭pH值升高速率逐渐放缓,其中在250~650℃的热解条件下,稻草的pH值升高幅度最大,木屑的pH值升高幅度最小,在350~450℃这一较为理想的热解温度区间范围内所制备的四种生物炭pH值的大小顺序依次为:稻草玉米秸秆鸡粪木屑。     

芦苇基和污泥基生物炭对水体中诺氟沙星的吸附性能

以芦苇秸秆和市政污水处理厂污泥为原料,在500℃的条件下制备了芦苇基和污泥基生物炭.利用比表面积测定法(BET)、扫描电镜(SEM)、能谱分析(EDS)和红外光谱(FTIR)研究了生物炭的结构与性质,并通过单因素实验研究p H、吸附时间、温度、诺氟沙星(NOR)初始浓度对吸附效果的影响,初步讨论了吸附机制.结果表明,NOR在芦苇基和污泥基生物炭上的吸附在12 h分别达到总吸附量的70%、60%以上;芦苇基和污泥基生物炭对NOR的饱和吸附量分别为2.13 mg·g-1和2.09 mg·g-1;降低溶液p H有利于NOR的吸附;生物炭对NOR的吸附行为符合准二级动力学方程,其等温吸附曲线符合Langmuir方程.对吸附过程吉布斯自由能(ΔG)、焓(ΔH)以及熵(ΔS)的计算证明生物炭对NOR的吸附是自发的吸热反应;红外光谱分析表明,生物炭上较多含氧官能团为NOR的吸附提供了吸附点,有利于NOR分子与生物炭间形成作用力较强的氢键,氢键为NOR吸附在生物炭上的主导作用力.     

杨木生物炭对水溶液中3种磺胺类抗生素的混合吸附

利用杨树木屑在限氧条件下,制备出3种不同热解温度下的生物炭,以探究其对水溶液混合磺胺类药物（SAs）的吸附机制。结果表明:350 ℃烧制的生物炭（BC350）孔径以大孔为主,而500 ℃（BC500）与650℃（BC650）以介孔为主;生物炭表面芳香性随着热解温度提高而增强。伪二级模型较适合描述生物炭吸附SAs的动力学过程;Freundlich等温模型对杨木生物炭拟合度较好;杨木生物炭具有较大的SAs吸附容量,BC650的SAs吸附容量为秸秆类生物炭的2.6~104倍。吸附热力学计算表明,杨木生物炭对磺胺吸附兼有物理吸附与化学吸附,以化学吸附为主。根据不同pH值条件下3种SAs的分子形态,得出3种SAs的竞争吸附能力依次为SPD>SMZ>SDZ。     

诺氟沙星吸附剂生物炭-壳聚糖复合微球的制备优化

为了提高生物炭-壳聚糖复合微球对NOR（诺氟沙星）的吸附能力,以复合微球对NOR的吸附量为指标,考察了生物炭与壳聚糖质量比、壳聚糖脱乙酰度、戊二醛用量、交联时间、交联速率及生物炭热解温度对复合微球吸附NOR的影响,并由均匀试验确定复合微球的最佳制备条件.结果表明,生物炭与壳聚糖质量比、壳聚糖脱乙酰度、戊二醛用量、交联时间、交联速率及生物炭热解温度对复合微球吸附NOR具有明显影响.制备复合微球的关键影响因素是生物炭热解温度、戊二醛用量和交联速率.吸附NOR的复合微球最佳制备条件:生物炭热解温度为300℃、生物炭与壳聚糖质量比为5:1、壳聚糖脱乙酰度为77%、戊二醛用量为80 mL、交联速率为150 r/min、交联时间为3 h.此时,复合微球对NOR的吸附量为9.51 mg/g,且具有较高的耐酸溶性和机械强度.研究显示,复合微球能够高效吸附NOR,并且吸附后容易分离,具有修复水体污染的潜力.      

花生壳和玉米芯生物炭对亚甲基蓝的吸附性能

选择花生壳和玉米芯为原材料分别在700℃和450℃条件下制备生物炭,考察了亚甲基蓝初始浓度、生物炭投加量、温度和pH对生物炭吸附亚甲基蓝的影响,并对吸附动力学和等温吸附特征进行了探讨。结果表明,生物炭投加量的增加使其对亚甲基蓝的吸附量下降,而去除率升高;提高亚甲基蓝初始浓度、反应体系温度和pH均会使生物炭对亚甲基蓝的吸附量增高; 4种生物炭对亚甲基蓝的吸附动力学过程均能被准二级动力学方程很好地拟合(R~2=0.992～0.999),吸附过程以化学吸附为主要控制步骤; 4种生物炭对亚甲基蓝的吸附更适合用Langmuir方程描述(R~2=0.992～0.995),PSB700、PSB450、CCB700和CCB450对亚甲基蓝的理论最大吸附量Q_(max)分别为10.247mg/g、6.449mg/g、7.919mg/g和2.860mg/g,吸附能力由大到小为PSB700 CCB700 PSB450 CCB450。     

水稻秸秆生物炭对磺胺类抗生素的吸附研究

研究了3种热解温度分别为300℃(S300)、450℃(S450)、600℃(S600)的水稻秸秆生物炭对两种磺胺类抗生素的吸附性能及机制,同时考察了溶液p H值及离子强度对吸附的影响。结果表明,生物炭对磺胺二甲基嘧啶(SM_2)和磺胺甲恶唑(SMX)的吸附均符合准二级动力学方程;等温吸附曲线用Langmuir方程拟合优于Freundlich方程,3种生物炭的最大吸附量随热解温度的升高而升高,且对SM_2的吸附能力优于SMX,600℃热解的秸秆炭对SM_2和SMX的最大吸附量分别可达到2 857.1 mg/kg和1 724.1 mg/kg。溶液p H显著影响吸附,SM2和SMX的吸附以中性形态为主,p H在3~11的范围内,SM_2和SMX的最佳p H分别为5和3。生物炭对2种抗生素的吸附能力随离子强度的升高而轻微下降。红外光谱分析表明,氢键结合、π-π共轭是秸秆生物炭吸附2种磺胺抗生素的主要机理。     

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.     

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.     

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.