Heterogeneous Fenton-like degradation of 4-chlorophenol using iron/ordered mesoporous carbon catalyst

Ordered mesoporous carbon supported iron catalysts(Fe/OMC) were prepared by the incipient wetness impregnation method and investigated in Fenton-like degradation of 4-chlorophenol(4CP) in this work. XRD and TEM characterization showed that the iron oxides were well dispersed on the OMC support and grew bigger with the increasing calcination temperature. The catalyst prepared with a lower calcination temperature showed higher decomposition efficiency towards 4CP and H2O2, but more metals were leached. The effect of different operational parameters such as initial pH, H2O2 dosage, and reaction temperature on the catalytic activity was evaluated. The results showed that 96.1% of 4CP and 47.4% of TOC was removed after 270 min at 30°C, initial pH of 3 and 6.6 mmol/L H2O2. 88% of 4CP removal efficiency was retained after three successive runs, indicating Fe/OMC a stable catalyst for Fenton reaction. 4CP was degraded predominately by the attack of hydroxyl radical formed on the catalyst surface and in the bulk solution due to iron leaching. Based on the degradation intermediates detected by high performance liquid chromatography, possible oxidation pathways were proposed during the 4CP degradation.     

Metal composition of layered double hydroxides (LDHs) regulating ClO4- adsorption to calcined LDHs via the memory effect and hydrogen bonding

A series of calcined carbonate layered double hydroxides （CLDHs） with various metal compositions and different M^2＋/M^3＋ ratios were prepared as adsorbents for perchlorate. Adsorption isotherms fit Langmuir model well, and the adsorption amount followed the order of MgA1-CLDHs 1〉 MgFeCLDHs 〉〉 ZnA1-CLDHs. The isotherms of MgA1-CLDHs and MgFe-CLDHs displayed a two-step shape at low and high concentration ranges and increased with an increase in the M^2＋/M^3＋ ratio from 2 to 4. The two-step isotherm was not observed for ZnA1-CLDHs, and the adsorption was minimally affected by the M^2＋/M^3＋ ratio. The LDHs, CLDHs and the reconstructed samples were characterized by X-ray diffraction, SEM, FT-IR and Raman spectra to delineate the analysis of perchlorate adsorption mechanisms. The perchlorate adsorption of MgA1-CLDHs and MgFe-CLDHs was dominated by the structural memory effect and the hydrogen bonds between the free hydroxyl groups on the reconstructed-LDHs and the oxygen atoms of the perchlorates. For ZnAI-CLDHs, the perchlorate adsorption was controlled by the structural memory effect only, as the hydroxyl groups on the hydroxide layers preferred to form strong hydrogen bonds with carbonate over perchlorate, which locked the intercalated perchlorate into a more confined nano-interlayer. Several distinct binding mechanisms of perchlorate by CLDHs with unique M^2＋ ions were proposed.     

C/N比对嗜酸细菌X-29产氢能力及其酶活性的影响

C/N比影响细菌的物质和能量代谢,为了提高产氢细菌的产氢效能,通过间歇产氢实验和酶活性分析方法,分析了在不同C/N比下嗜酸产氢细菌X-29的产氢能力以及氢化酶和乙醇脱氢酶的活性表达情况.研究结果表明,C/N比对产氢细菌的代谢及其相关酶的表达有显著的影响.虽然在不同C/N比下单位生物量的液相末端发酵产物差异不大,但是产氢能力存在显著的差异,当C/N比为14时产氢细菌X-29具有最大累积产氢量2 210.9mL/g.在不同C/N比下氢化酶的表达活性不同,氢化酶活性随着发酵的进行达到高峰后迅速降低,氢化酶的表达周期较短.乙醇脱氢酶活性随着代谢进程逐渐升高后而趋于平稳,不同C/N比时表达活性差异较小,表达周期较长.在C/N比为14时,氢化酶和乙醇脱氢酶的活性最高,分别为2.8μmol·(min·mg)^-1和33.2μmol·(min·mg)^-1.     

硫化氢的危害与防治

对硫化氢在油气田中的存在状况和危害性的研究结果表明,其主要危害是引起人员中毒以及氢脆作用造成的油田设备腐蚀。详细介绍了防治硫化氢的方法和措施,包括沉淀法、物理吸收法、钾碱法和氨水法、氧化法、金属氧化物吸收法、高压静电法等。对各种方法的防治机理及其应用状况进行了论述。     

光导纤维生物膜碘荧光传感器的研究

把荧光素固定在经处理的生物膜上，研制成光导纤维生物膜碘荧光传感器。Ｉ－的线性响应范围为３×１０－５ｍｏｌ／Ｌ—５×１０－３ｍｏｌ／Ｌ，相对标准偏差为０６５％，响应时间为２５～３５ｍｉｎ。     

Removal of Cinnamic Acid Derivatives from Aqueous Effluents by Fenton and Fenton-like Processes as an Alternative to Direct Biological Treatment

The removal of various phenolic acids (p-coumaric, caffeic and ferulic acids), typically found in wastewaters of agricultural origin, from model effluents by chemical and biological means has been investigated. Chemical oxidation processes comprising hydrogen peroxide and a homogeneous or heterogeneous copper or iron catalyst were employed over a wide range of experimental conditions. Chemical oxidation is capable of removing most of the total organic carbon initially present in the effluent at relatively mild treatment conditions (i.e. reaction times up to 120 min and temperatures up to 80°C), while removal rates generally increase with increasing temperature, H₂O₂ and catalyst concentrations. The anaerobic degradability and toxicity of p-coumaric acid has been assessed using the biochemical methane potential and anaerobic toxicity assay respectively. p-Coumaric acid, at concentrations below about 1 g/L, is not toxic against methanogens and slowly degrades over a period of about 35 days at 35°C. In light of this, chemical oxidation may provide a promising alternative to direct biological treatment for either the partial or complete removal of phenolic acids at reasonable treatment times; the implications for wastewater treatment are discussed.     

酸催化氧化法处理含对苯二酚废水的方法

本文主要研究用硫酸作催化剂，30％过氧化氢作氧化剂，再经过pH值的调节和活性炭吸附，使对苯二酚化学需氧量值从3615mg／L降至260mg/L。化学需氧量的去除率高达93．3％。     

总磷测试消解方法的改进

用过氧化氢-沸水浴消解法测定水样中的总磷,结果表明,新消解方法具有操作简单,消解完全的特点,与传统方法具有良好的可比性,精密度和准确度均令人满意。     

氢氰酸原料化工生产装置的安全对策

由于氢氰酸既有剧毒性又有火灾爆炸的危险性,采用氢氰酸为生产原料的化工生产企业,安全生产只有依据国家规范和标准,从防毒、防火防爆等几个方面来全面制定安全对策,才能防范安全生产事故的发生.     

亚铁－过氧化氢氧化法处理染料中间体H酸生产废液的研究

Ｈ酸生产过程中排出的废液中含有大量萘的衍生物,对生物具有毒性,是目前最难处理的废水之一。本研究采用亚铁－过氧化氢氧化法对该废液进行处理,以改善它的可生化性能,降低水中有机物的溶解性,提高混凝处理效率。结果表明,最佳pH值为2～4,亚铁的适宜投加量为200mg/L,当H₂O₂投加量为30g/L时,COD去除率为50％,废水已具有可生化性。经亚铁－过氧化氢氧化处理（H₂O₂的投加量为3g/L）后的废液,再用FeCl₃进行两级混凝处理（FeCl₃的量分别为15和5g/L）,COD的去除率达90％,H酸氧化过程中,HO先和萘环上的钝化基团发生置换反应,使萘环活化,进一步氧化,萘环裂解,最终转化为无机物。研究结果对提高该种废水生物处理效率有实用意义。