高铁酸钾制备影响因素的实验研究

文章介绍了湿法制备高铁酸钾的工艺,研究了次氯酸盐浓度、氧化反应温度、铁盐原料选择、洗涤所用溶剂种类等对高铁酸钾纯度和产率的影响。实验表明在制备次氯酸盐溶液时用冰水浴反应温度控制为20℃,选用37.5%的KOH溶液,可制得ClO-质量分数为123.5 g/L的饱和次氯酸钾溶液。实验还表明制备高铁酸钾的最佳反应时间为45 min,硝酸铁投加量为化学计量的80%时,可得到纯度为80%～90%、产率为71%的高铁酸钾固体产物。通过实验提出在0℃饱和的氢氧化钾溶液中不断搅拌,高铁酸钾晶体可以充分析出。     

高铁酸钾氧化去除水中三氯生的研究

采用高铁酸钾对水中三氯生（TCS）的去除进行了研究,探讨了TCS的降解机理,考察了高铁酸钾投加量、pH值、天然有机物（NOM）和双氧水等因素对TCS去除和中间产物2,4-二氯苯酚（2,4-DCP）生成的影响.结果表明：TCS通过醚键断裂降解生成2,4-DCP,TCS浓度为550μg/L,高铁酸钾浓度为15mg/L时,600s后TCS去除率可达96.48%.增加高铁酸钾投加量可以提高TCS的去除,TCS的去除率随pH值升高呈现出降低的趋势,酸性环境有利于TCS的去除,pH值为4时,TCS的去除达100%,腐殖酸和双氧水对TCS的去除有抑制作用.高铁酸钾可以有效降解TCS并降低溶液的急毒性,降低水质健康风险.     

经济絮凝剂优化处理印染废水试验研究

通过几种常用絮凝剂的筛选试验,以COD、色度为指标考察絮凝剂对印染废水处理效果的影响,得出了硫酸亚铁具有较高处理效果和较低药剂成本的结果.通过pH值试验和镁盐、亚铁盐质量比试验,确定复合絮凝剂的最佳使用条件为石灰乳,投加量质量浓度为300 mg·L-1,镁盐亚铁盐质量之比1:1.组合方案对比试验表明,MFSC复合絮凝体系对印染废水处理效果最好,其质量浓度分别在熟石灰投加量为300 mg·L-1,镁盐300 mg·L-1,硫酸亚铁300 mg·L-1时,CODCr去除率达68%,脱色率达95%,而药剂成本每吨废水仅为0.17元.     

垃圾渗滤液浓缩液高铁酸钾联合PAC处理技术研究

以碟管式反渗透(DTRO)处理垃圾渗滤液产生的浓缩液为研究对象,采用高铁酸钾联合聚合氯化铝(PAC)处理浓缩液.结果表明,在单独采用高铁酸钾的条件下,DTRO浓缩液COD、UV_(254)和色度去除率随着高铁酸钾投加量的增加而升高.高铁酸钾投加量为10 g·L~(-1),pH为5时,COD、UV_(254)和色度去除效果最佳,反应在40 min内基本完成,COD、UV_(254)、色度去除率分别为38.5%、35.7%和68.5%.通过响应曲面法分析高铁酸钾联合PAC处理DTRO浓缩液效果可得,高铁酸钾投加量在10.0～13.0 g·L~(-1)之间,pH调节至3.0～4.0,PAC投加量为13.0～15.0 g·L~(-1)时,DTRO浓缩液COD去除率可达74%.     

模拟沉积磷迁移转化行为的铁盐影响机制研究

室内模拟研究了沉积物中不同形态磷在不同浓度铁盐影响下,在沉积层中的垂直迁移转化行为.结果表明,分别向模拟系统投加的10 mL和50 mL的1 mol/L FeCl_3溶液,沉积层中磷的含量降低,投加30 mL的1 mol/L FeCl_3溶液时,沉积层中磷含量增加.沉积物中适当的铁盐会阻止沉积物磷向水体释放,铁盐浓度过高或过低,在一定程度上都会促进沉积物中磷的释放,实验结果对研究内源磷释放与湖泊富营养化有重要的意义.     

高铁盐与亚铁盐混凝除As(Ⅲ)性能的对比研究

为研究不添加氧化剂时,高铁、亚铁盐混凝—过滤法净化低浓度As(Ⅲ)污染饮用水的可行性及对比两种铁盐除As(Ⅲ)性能差异,本试验分别从铁盐投加量、混凝最佳p H值、吸附容量、亚铁氧化去除As(Ⅲ)能力等方面,系统比较了亚铁盐和高铁盐去除As(Ⅲ)工艺性能.结果表明:在相同的试验条件下,高铁盐能够有效净化低浓度含As(Ⅲ)水,其投加量不足亚铁盐的一半,且出水p H波动较小.吸附是混凝除砷过程的主要机理,随铁盐投加量增加,吸附贡献率不断增加,且高铁盐吸附除砷效率始终比亚铁盐高.高铁、亚铁盐絮凝颗粒吸附除As(Ⅲ)的平衡时间为6h,最大吸附量分别为42.445和50.865mg/mg;亚铁盐能够催化氧化进水中40%左右的As(Ⅲ),但吸附效率较差,除As(Ⅲ)效果不及高铁盐.     

高铁酸钾氧化法处理电子工业清洗废水的试验研究

电子工业清洗废水是较难生物降解的工业污水之一,因此,须采用其他方法对其进行处理。文章通过室内烧杯试验研究了采用高铁酸钾氧化法处理该种废水的影响因素和方法,当该种废水的COD浓度在500～800mg/L范围内时,调整废水pH=2左右,投加量高铁酸钾3g/L左右,并分次投加,则当反应时间超过30min后,其COD的去除率可达40%左右,且效果稳定。活性炭吸附可以进一步去除高铁酸钾反应出水的COD,当活性炭投加量高于10g/L,吸附反应5h时,出水COD低于100mg/L,符合排放标准。     

铁盐和铝盐混凝微滤工艺除As(V)的比较研究

选择FeCl₃和Al₂(SO₄)₃作混凝剂,采用小试规模的混凝微滤膜反应器比较了铁盐和铝盐混凝微滤工艺的除As(V)效果、相关性能指标及适用范围.结果发现,Fe³⁺投加量为4 mg/L、Al₂(SO₄)₃投加量为50 mg/L时,铁盐和铝盐工艺的除As(V)效果大致相当,均可使水中As(V)的浓度从100 μg/L左右降低到10 μg/L以下,最低为1.68 μg/L.出水浊度均小于0.1 NTU,出水中铁、铝和SO^2-₄浓度均符合饮用水标准.铁盐工艺出水pH值比原水大约高0.5,铝盐工艺处理前后水的pH值基本不变.反应器运行结束静沉24 h后,铁盐工艺浓缩比为1 791,是铝盐工艺的2.54倍,污泥中As(V)的含量也大大高于铝盐工艺,去除同等重量的As(V)所产生的污泥量较铝盐工艺少得多.因此,对于仅有砷超标的饮用水,应优先考虑铁盐工艺.按除氟所需混凝剂数量投加Al₂(SO₄)₃,铝盐工艺即可在去除As(V)的同时去除氟,铁盐工艺则不能去除氟.因此,对于砷和氟均超标的饮用水,可采用铝盐工艺同时去除砷和氟.     

K+对Fe(Ⅵ)生成的稳定促进作用和机理研究

研究了在生成高铁酸盐反应过程中K 对Fe(Ⅵ)的稳定促进作用和机理.结果表明,当反应温度大于50℃时.K 比Na 更有利于高铁酸盐的生成.K 促进高铁酸盐溶液生成的最佳反应温度为65℃.在生成高铁酸盐反应过程中,增加K 浓度能提高高铁酸盐的产率,并且随着硝酸铁投加量的增加,K 影响显著.在硝酸铁投加量为85 g/L时,采用4.4 mol/L KOH制备的Fe(Ⅵ)浓度为0.05 mol/L;加入2 mol/L K 后,Fe(Ⅵ)浓度增加到0.15 mol/L.K 对高铁酸盐溶液生成浓度的影响在硝酸铁投加量大于75 g/L,反应温度低于55℃,CIO-浓度低于1.16 mol/L时较为显著.K 在一定程度上可替代部分碱度,降低OH-用量.在反应过程中K 能包裹在FeO24-周围,减少Fe3 与FeO24- 接触,从而减缓Fe3 对FeO24-的催化分解作用;同时K 能与FeO24-生成K2 FeO4)晶体沉淀析出,降低溶液中FeO24-浓度,Fe(Ⅵ)分解速率减缓,稳定性增加,Fe(Ⅵ)生成浓度增加.     

高铁酸钾水处理剂预处理矿井水的试验研究

利用高纯度高铁酸钾,进行了矿井水处理试验,结果表明：在简单的工艺条件下。高铁酸钾投加量在24mg／L以上时,经处理的矿井水剩余CODcr小于6mg／L;高铁酸钾浓度大于7mg／L时,经处理的矿井水残余的总大肠菌群数小于3个／L,杀灭率可这98％以上;高铁酸钾投加量大于24mg／L,可以使混凝后的矿井水浊度达到5NTU左右。     

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.     

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.     

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.     

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.