Decolourisation of aqueous dyes by sequential oxidation treatment with ozone and Fenton's reagent

Combined oxidation with ozone and Fenton's reagent (‘Fentozone’ process) for decolourisation of aqueous dyes was studied and compared with traditional Fenton's reagent. Although the ‘Fentozone’ process was found to be effective at a wide range of pH values, the maximum colour removal was achieved at pH 4. The effect of pre‐ozonation on colour removal efficiency of aqueous dyestuffs in the subsequent treatment with Fenton's reagent was investigated. The reaction kinetics using water‐soluble acid and reactive dyes were also studied. Our experimental results show that pre‐ozonation can considerably accelerate decomposition of dyestuffs in the subsequent treatment with Fenton's reagent. Different concentrations of ferrous sulfate were used to investigate their influences on the removal of colour. The rate of reaction increased with increasing doses of ferrous sulfate. © 2002 Society of Chemical Industry     

Modification of zeolite surfaces by Grignard reagent

New microporous hybrid organic/inorganic materials were obtained by modification of zeolites using chlorination of their surface, followed by treatment with a Grignard reagent. Loading of butyl groups and retained crystallinity of ZSM-5 type zeolites was higher than for zeolites Y. In contrast to zeolites Y, the lattice parameters of zeolites ZSM-5 increased after surface modification. The obtained hybrid materials on the basis of high-silica zeolites possess a high degree of crystallinity at increased hydrophobicity.     

酚试剂法测定室内空气中甲醛的实验条件优化

为了提高酚试剂法测定室内空气中甲醛的准确性,优化实验条件,系统研究了盐酸介质浓度、显色剂加入量、显色时间、显色反应温度和稀释液类型等因素对吸光度的影响,研究结果表明,采用0.1 mol/L盐酸配制的硫酸铁铵显色剂,显色剂加入量对吸光度影响不显著,最佳加入量为0.4 mL;显色反应温度对吸光度影响明显,最佳温度应控制在25～35℃范围内;稳定的显色反应时间应控制在18～30 min内,以20 min为宜;当甲醛质量浓度较高时,可选用去离子水或酚试剂吸收液进行适当的稀释。在较优的实验条件下,测定的甲醛质量浓度与吸光度在0～2.0μg/mL范围内呈良好的线性关系,r=0.999 9。     

用Fenton试剂-矿化垃圾生物反应器联合处理离子交换树脂再生废水

研究了Fenton试剂-矿化垃圾生物反应器联合处理离子交换树脂再生废水.研究结果表明：当原水CODCr为413 mg/L和过氧化氢投加量为24 mL/L（废水）时,经Fenton试剂预处理后,再经矿化垃圾生物反应器后续生化处理（运行周期为4 h,1 h进水,3 h落干,进水流量为600 mL/h）,出水CODCr降至85 mg/L左右,达到国家排放标准.     

Reaction of sodium perborate with a chlorinated cyclic hindered amine (TMP-Cl): I. Quantitative evaluation of active oxygen species in fabric bleaching

The reaction of N-chloro-4-hydroxy-2,2,6,6-tetramethylpiperidine (TMP-Cl) with sodium perborate (PB) was investigated with special reference to the generation of singlet oxygen and the possible application to a new oxidative bleaching process. Generation of the singlet oxygen (¹O₂), the hydroxyl radical (HO·) and superoxide anion radical (O₂·⁻) in the PB/TMP-Cl mixed solution was confirmed by the trapping reagent method. From the results of another experiment, in which the bleaching abilities of each active oxygen species were confirmed, the main active oxygen species contributing to the bleaching of purpurogallin, the skeleton of black tea pigment, in the PB/TMP-Cl system was concluded to be¹O₂.     

Solvent free oxidation of alcohols catalyzed by KMnO4 adsorbed on Kieselguhr

Efficient and selective oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones catalyzed by potassium permanganate supported on Kieselguhr reagent under solvent free conditions are reported.     

Investigation into the flotation response of refractory molybdenum ore to depressant mixtures:A case study

In this paper, bulk flotation followed by separation was investigated to concentrate purified molybdenite product from Jinduicheng molybdenum ores(Shanxi province, China). The bench scale tests mainly focussed on separation of molybdenite from other sulfide minerals using the new type of depressants.The effect of each single depressant, including organic depressant-modified dextrin(MD), P-Nokes reagent(PN) and sodium trithiocarbonate(ST), and their mixtures on galena, chalcopyrite and other sulfide ores, was examined in turn by changing the concentrations used in cleaner flotation tests. Closed circuit experiments were carried out under the optimal condition and satisfying recovery and grade of molybdenite concentrate could be achieved(86.294% and 53.157%, respectively). A potential reagent regime was developed, with more environmental friendly and more economical advantages due to the introduction of modified dextrin.     

混凝-Fenton氧化联合工艺处理有机废水的试验研究

利用多种方法联合处理是废水处理技术的发展方向,通过单因素实验确定了Fenton氧化和混凝处理高浓度有机废水的最佳参数,并进行了联合工艺处理该废水的实验。结果表明:采用Fenton-混凝联合工艺处理高浓度有机废水优于混凝-Fenton法,处理后苯酚含量、CODCr和浊度分别为45.2mg/L、818.2 mg/L和0.1 NTU,去除率分别为95.5%、60.1%和99.9%。     

2-（4-氯苯氨基）甲基苯酚降解的动力学研究

采用高效液相色谱技术,开展了Fenton试剂对2-（4-氯苯氨基）甲基苯酚（CMP）的氧化降解动力学的研究。考察了初始双氧水摩尔浓度、亚铁离子摩尔浓度和温度等因素对CMP降解速率的影响,结果表明,当双氧水摩尔浓度、亚铁离子摩尔浓度增大和温度升高时,CMP的氧化速率明显加快。在30~45℃的温度范围内,其氧化降解符合假一级反应动力学模型,反应的表观活化能Ea为102.90kJ/mol。     

Coat-nitrocarburizing using triazine polymer reagent

A chemico-thermal treatment process, coat-nitrocarburizing, has been developed for use on iron and steel. The process consists of treating the workpiece with a coat that forms on the surface from the gaseous products of sublimation and decomposition of a triazine polymer reagent in a closed volume. The process can be used over a wide range of temperatures, either below the eutectoid transformation temperature in the Fe-N-C system for low-temperature nitrocarburizing, or above this temperature for hightemperature nitrocarburizing in different applications. The process is very simple, easily controlled, and is economic. In addition, it is a nonpolluting process, unlike conventional chemico-thermal treatment processes that discharge harmful gases into the atmosphere.