纳米Fe-C合金去除染料废水中酸性橙Ⅱ的初步研究

本文研究了碳包纳米铁对酸性橙Ⅱ的吸附。研究结果表明,在酸性橙Ⅱ初始浓度40 mg/L,碳包铁浓度1.5 g/L,转速240 r/min,p H为6.2,温度30℃的优化条件下,吸附120 min后,酸性橙Ⅱ的去除率达到90.0%,吸附量达到了24.2 mg/g;吸附前后碳包纳米铁的XRD谱图未发生明显的变化,吸附后溶液中酸性Ⅱ的UV-vis特征吸收峰几乎消失了;碳包纳米铁对酸性橙Ⅱ的吸附过程符合Langmuir吸附等温线,吸附动力学符合伪二级动力学模型。     

载铁活性炭对水中草甘膦吸附性能研究

通过浸渍-焙烧法制备载铁活性炭,并用SEM电镜分析了载铁活性炭表面形态,研究了载铁活性炭(Fe-AC)对草甘膦溶液的吸附等温线和吸附动力学,并分析了各种影响因素对载铁活性炭吸附性能的影响.实验表明,Freundlich方程可以对Fe-AC草甘膦吸附等温线进行很好拟合,最大吸附量约为5.8mmol/g;其吸附动力学过程用Lagergren方程拟合,吸附速率常数在0.088min-1左右,且随着温度的升高逐渐减小.根据Kannan & Sundaram颗粒内扩散模型拟合,颗粒内扩散速率常数kp大于10mg·min-1/2/g,并随着起始温度的升高而减小.由于草甘膦的存在形态和Fe-AC材料表面性质的变化,AC-Fe对草甘膦的吸附能力随水溶液的pH升高而降低.NaCl的存在产生拮抗效应使得Fe-AC对草甘膦的吸附容量大大下降,随着NaCl浓度增加至4g/L后,盐析效应开始占主导地位,使得Fe-AC的吸附容量略有增加;由于草甘膦分子的空间位阻效应和亚磷酸根与载铁活性炭表面形成较强的络合物,使得随亚磷酸根浓度的升高Fe-AC对草甘膦的吸附量持续下降.     

磁性铁氧化物修饰碳纳米管去除水中红霉素的研究

通过化学共沉淀法制备铁氧化物修饰的多壁碳纳米管(MWCNTs)用于去除水中红霉素,对铁氧化物修饰的多壁碳纳米管(MWCNTs)进行X-射线衍射分析与磁强测定,研究去除红霉素的效果及影响效果的因素,探讨吸附动力学、热力学与吸附机理。结果表明:铁氧化物为磁性的Fe_3O_4和γ-Fe_2O_3,磁性良好,可从水中通过磁分离回收。磁性铁氧化物修饰后显著提高MWCNTs对红霉素的去除效果,对于红霉素初始浓度为20 mg/L,0.5 g/L磁性的MWCNTs 30 min红霉素去除率达到87.23%。红霉素去除率随吸附剂投加量的增大而增大,随红霉素初始浓度的增大而下降,随p H值的提高而略有增大。吸附过程遵循拟二级动力学模型和Langmuir吸附等温方程,是以物理吸附为主,化学吸附为辅的吸热反应。吸附红霉素的磁性MWCNTs通过微波辐射可实现再生循环使用,具有应用前景。     

对印染废水中甲基橙去除的新方法研究

本文主要研究了碳纳米管-铁氧化物磁性复合材料(磁性碳纳米管)在吸附处理甲基橙方面的应用。分别研究了甲基橙初始浓度、吸附剂投加量、吸附时间、溶液温度和p H值等工艺条件对甲基橙吸附率的影响。结果表明,在甲基橙初始浓度为2 mg/L,吸附剂投加量4 g/L,吸附时间30min,p H值为3的条件下,吸附率达到了63.99%。磁性碳纳米管吸附甲基橙的吸附率随着吸附剂的用量增大而增大;在20 min以前,甲基橙的吸附率随着时间的增加而增大,到达30 min后吸附率基本保持不变;甲基橙的吸附率随着起始甲基橙的浓度的增加而减小。另外,酸性溶液有利于磁性碳纳米管吸附甲基橙,随着p H的增大吸附率逐渐减小,当溶液呈碱性时,p H对吸附率的影响逐渐减小。     

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。     

改性泥炭-树脂颗粒对水溶液中酸性橙Ⅱ的吸附

通过批量实验研究了改性泥炭-树脂颗粒对水溶液中酸性橙Ⅱ的吸附特性.Langmuir和Freundlich吸附等温方程被用于分析吸附等温数据,准一级动力学模型、准二级动力学模型和颗粒扩散模型被用于吸附动力学实验数据分析.结果表明,改性泥炭-树脂颗粒对水溶液中酸性橙Ⅱ的吸附过程符合Langmuir和Freundlich吸附等温方程,最大吸附量达到71.43 mg·g^-1;颗粒扩散模型能够很好地描述改性泥炭-树脂颗粒对水溶液中酸性橙Ⅱ的吸附动力学过程,水溶液中染料的初始浓度、颗粒直径、颗粒量及搅拌速度对吸附速率均产生一定的影响.改性泥炭-树脂颗粒对水溶液中酸性橙Ⅱ的吸附作用主要发生在颗粒的外表面.     

生姜秸秆基多孔活性炭的研制及吸附性能研究

文章以生姜秸秆为原料,采用氯化锌活化法制备生姜秸秆基多孔活性炭,优化材料最佳制备条件。利用扫描电子显微镜、X射线衍射仪、氮气吸附物理分析仪、傅里叶红外光谱和拉曼光谱等表征手段对生姜秸秆基多孔活性炭形貌结构以及化学组成等进行分析,并考察溶液pH值、吸附时间、温度和初始浓度对其吸附亚甲基蓝(MB)染料的影响。结果表明：生姜秸秆基多孔活性炭最佳制备条件为氯化锌与生姜秸秆质量比2∶1、活化温度500℃、活化时间1 h。制备活性炭具有大量的孔径结构和丰富的表面基团,对MB吸附效果明显,吸附量最高可达565.0 mg/g。溶液pH、初始浓度、吸附时间和温度对活性炭吸附性能有一定影响,吸附过程符合准二级动力学模型和Langmuir等温线模型。该研究制备的生姜秸秆基多孔活性炭材料结构和吸附性能优良,可作为优质吸附剂应用于污水处理领域,同时为生姜秸秆的资源化利用提供新途径。     

磷酸法活化银杏叶活性炭对DBP的吸附性能研究

以银杏树叶为原料,使用磷酸活化法制备粉末活性炭,采用银杏叶粉末活性炭作为吸附剂,研究了其对DBP的吸附性能.研究考察了温度、吸附时间、pH对DBP吸附性能的影响,同时拟合了吸附等温线,探讨了热力学和动力学性质.结果表明温度、吸附时间、pH对吸附效果均有影响,吸附过程符合Langmuir吸附等温方程,吸附过程是自发的,二级动力学方程更好地描述吸附动力学规律.     

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.     

活性炭非均相活化不同过硫酸盐降解偶氮染料酸性橙Ⅱ

研究了颗粒活性炭非均相活化过二硫酸盐和过一硫酸盐对水中偶氮染料酸性橙Ⅱ的降解效果。考察了过硫酸盐投加量、活性炭投加量、溶液初始pH值和无机阴离子对酸性橙Ⅱ降解率的影响,探究了不同过硫酸盐对染料降解效果差别的原因。结果表明:投加过二硫酸盐比过一硫酸盐的效果更好,偶氮染料浓度为20 mg/L,溶液中过n（PS）∶n（AOⅡ）为200∶1时降解率最高;颗粒活性炭投加量的增加有利于染料的去除,溶液处于酸性条件下染料降解率高于碱性条件,无机阴离子对酸性橙Ⅱ降解有抑制作用,产生于活性炭表面的自由基对染料的降解具有重要作用。     

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.     

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.     

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

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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.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

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.     

Sorption of 1-naphthol by plant cuticular fractions

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.     

Seed selections for crystallization of calcium phosphate for phosphorus recovery

Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.