共查询到17条相似文献,搜索用时 109 毫秒
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《应用化工》2022,(12):2809-2814
采用Pluronic F-127改性纳米零价铁后负载镍,形成改性纳米铁镍(F-NZVI/Ni)。探讨了Ni的负载量、F-NZVI/Ni的投加量、2,4-DCP初始浓度、pH及反应温度对2,4-DCP去除率的影响。同时探究了F-NZVI/Ni去除2,4-DCP的最佳条件下F-NZVI/Ni去除2,4-DCP的反应过程。结果表明,F-NZVI/Ni去除2,4-DCP的能力优于NZVI,当F-NZVI/Ni投加量为3 g/L,镍负载率为5%,2,4-DCP初始浓度为20 mg/L,反应温度为35℃,初始pH值为7时,2,4-DCP的去除率为97%。F-NZVI/Ni去除2,4-DCP主要是先吸附,然后在镍催化剂作用下将2,4-DCP降解为苯酚。 相似文献
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为更好地理解纳米零价铁(nZVI)激活过硫酸盐(PS)的机制和动力学,基于Langmuir-Hinshelwood机理,结合nZVI/PS体系中主要的反应步骤对2,4-二氯酚(2,4-DCP)的降解过程建立动力学模型。使用不同影响因素下(包括nZVI投加量、初始PS浓度和初始2,4-DCP浓度)PS,2,4-DCP浓度变化数据拟合动力学模型并确定速率常数,通过对速率常数的敏感性分析得到:2,4-DCP降解的整体反应动力学是由前体表面复合物内部发生电子转移反应形成硫酸根自由基SO4·-以及2,4-DCP被羟基自由基OH·降解这两个过程来控制的。 相似文献
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《应用化工》2022,(8):1569-1572
以聚乙二醇(PEG)为分散剂,在乙醇-水混合溶剂中合成改性纳米级零价铁颗粒(nZⅥ)。利用透射电子显微镜(TEM),X射线衍射仪(XRD)对其结构、组成和物理性质进行表征,讨论了n ZVI去除Cr(Ⅵ)的影响因素,并对反应产物进行XPS检测。结果表明,乙醇比例为50%时制备出的纳米零价铁直径在3060 nm,对Cr(Ⅵ)的去除率最高,为95.30%。nZⅥ投加量越大,Cr(Ⅵ)初始浓度越小,p H越小,温度越高,均有利于水中Cr(Ⅵ)的去除。纳米零价铁将Cr(Ⅵ)吸附后将其还原为Cr(Ⅲ),反应过程主要以还原作用为主。并且对Cr(Ⅵ)的去除能用准一级反应动力学方程描述。 相似文献
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《应用化工》2022,(3):565-567
为了提高纳米铁的活性和分散性,在醇水体系下制备出纳米钯铁(Pd/Fe)双金属颗粒并表征,将制得的纳米Pd/Fe颗粒应用于水中2,4-二氯苯酚(2,4-DCP)的去除,考察了材料投加量、反应温度、初始pH值、2,4-二氯苯酚初始浓度等因素对2,4-DCP去除的影响,分析了2,4-DCP的去除机理并进行动力学拟合。结果表明,在醇水体系中制备纳米铁有利于纳米颗粒的稳定分散;钯的加入将脱氯途径转变为催化加氢,极大改善了2,4-DCP的去除效果;当2,4-DCP初始浓度为20 mg/L、反应温度30℃、纳米Pd/Fe颗粒投加量为2 g/L时,2,4-DCP可在5 h内去除99.9%;反应过程符合修正的一级反应动力学方程。 相似文献
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《应用化工》2022,(3):540-544
采用改性硅藻土(CD)作为载体,制备了改性硅藻土负载纳米零价铁复合材料(CD-nZⅥ)。利用透射电子显微镜(TEM)、XPS对CD-nZⅥ复合材料进行表征,并讨论CD-nZⅥ复合材料中nZⅥ与改性硅藻土质量比、CD-nZⅥ复合材料投加量、Cr(Ⅵ)初始浓度、pH、反应温度对CD-nZⅥ去除六价铬的影响因素。结果表明,CD-nZⅥ复合材料对六价铬的去除能力高于nZⅥ、改性硅藻土,CD-nZⅥ复合材料中nZⅥ与改性硅藻土质量比为1∶2,CD-nZⅥ投加量为0.8 g/L,反应温度为45℃,反应时间为120 min,pH=3,六价铬初始浓度为20 mg/L时,CD-nZⅥ对六价铬的去除效率高达99.16%。CD-nZⅥ去除六价铬的反应符合准一级反应动力学方程,反应速率常数K_(obs)随着六价铬浓度的增加而减少。对反应产物进行XPS检测,结果显示,CD-nZⅥ是通过还原、吸附作用去除六价铬,且以还原作用为主。 相似文献
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水中硝酸盐氮(NO3--N)的危害对人类健康和生态环境构成了严重威胁,纳米零价铁(nZVI)可以通过化学反应反硝化技术快速去除水中NO3--N,但nZVI自身易团聚,表面活性颗粒不稳定,所以在NO3--N还原过程中存在着氮气(N2)的选择性较低、NO3--N去除率不理想的问题。通过对nZVI去除NO3--N技术的归纳总结,探讨了nZVI在还原NO3--N的基本原理,影响因素和提高去除效率和N2选择性的改性方法。通过负载纳米材料,表面活性剂及添加还原剂等,NO3--N去除率和N2选择性都会得到不同程度上的提高。不同的改性方法对nZVI的改性效果不同,也决定了nZVI复合材料对NO3- 相似文献
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利用液相还原法制备硅酸钙负载零价纳米铁(CS-nZⅥ)进行去除水中Cr(Ⅵ)的实验研究.结果表明,CS-nZⅥ对Cr(Ⅵ)的去除效果明显优于还原铁粉和硅酸钙,略差于零价纳米铁;低pH值、越低初始Cr(Ⅵ)浓度及较大投加量均有利于Cr(Ⅵ)去除,最大去除率可达98.9%;反应后CS-nZⅥ颗粒扫描电镜及X射线能谱分析结果表明Cr占3.06wt%;等温吸附实验结果表明较好拟合Langmuir和Freundlich等温吸附模型,CS-nZⅥ对Cr(Ⅵ)的最大吸附容量达253.8 mg/g. 相似文献
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Kanagasabai Muruganandam Ponvel Dhamodaran Kavitha Kyung-Min Kim Chang-Ha Lee 《Korean Journal of Chemical Engineering》2009,26(5):1379-1382
To remove 2,4-dichlorophenol (2,4-DCP) from aqueous solution, the surface of the activated carbon was first treated with HCl
and then the surface was modified by using various metal ions (Cu, Co, Fe, Ni, Zn, and Mg). Metal doping significantly enhanced
the adsorption efficiency of activated carbon, an effect that was further increased by HCl treatment of the modified activated
carbons. Of all the preparations, the zinc(II)-modified activated carbon with HCl treatment showed the highest adsorption
capacity for 2,4-DCP. Analysis of the zinc(II)-modified activated carbon by SEM and BET showed a surface area and micropore
volume of around 1,154.69 m2/g and 0.291 cm3/g, respectively, values about 20% higher than in the starting material. In the pH range of 2.0–11.0, the maximum uptake of
2,4-DCP from an initial concentration of 1,000 mg/L was 508 mg/g at pH 4.0. 相似文献
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《Ceramics International》2022,48(20):30206-30217
The SiCN/Fe/Ni ceramics codoped with iron acetylacetonate (FA) and nickle acetylacetonate (NA) was synthesized by polymer-derived ceramics (PDCs) method in this study. The microstructure, phase composition and electromagnetic wave (EMW) absorption properties of the samples were analyzed. The polarization loss and conduction loss of materials were analyzed by the direct current (DC) multimeter and the contribution rate of polarization loss was more than 94% in the whole frequency band. The results showed that C, SiC, Fe2Si, Ni3Si, γ- (Fe, Ni) and CNTs were formed after pyrolysis which provided lots of heterogeneous interface and enhanced the interfacial polarization. Meanwhile, Ni could enter the lattice of Fe and formed a unique electronic configuration, which reinforced the conductivity and stability of Fe. In addition, the in-situ generated Fe2Si and Ni3Si provided magnetic loss and conduction loss. The RLmin value of SiCN/Fe/Ni-3 ceramic was ?52.06 dB at 1.54 mm and the effective absorption band (EAB, RL ≤ ?10 dB) reached 4.21 GHz (13.79–18 GHz, 1.43 mm). 相似文献
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Pd/C catalyst was prepared by hydrogen reduction method and used for the Pd/C gas-diffusion electrode. It was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) techniques. The electrochemical degradation of 2,4-dichlorophenol was investigated in a diaphragm electrolysis system, feeding firstly with hydrogen gas then with air, using the Pd/C gas-diffusion electrode and the carbon/polytetrafluoroethylene (C/PTFE) gas-diffusion electrode as a cathode, respectively. The results indicated that the self-made Pd/C gas-diffusion cathode can not only reductively dechlorinate 2,4-dichlorophenols by feeding hydrogen gas, but also accelerate the two-electron reduction of O2 to hydrogen peroxide (H2O2) by feeding air. Therefore, both the removal efficiency and the dechlorination degree of 2,4-dichlorophenol reached about 100% after 80 min, and the average removal efficiency of 2,4-dichlorophenol in terms of total organic carbon (TOC) exceeded 76% after 160 min by using Pd/C gas-diffusion cathode, which were better than that of the C/PTFE gas-diffusion cathode. The analysis of high-performance liquid chromatography (HPLC) identified that 4-chlorophenol, 2-chlorophenol, and phenol were the dechlorination products, and hydroquinone, benzoquinone, maleic, fumaric, crylic, malonic, oxalic, acetic and formic acids were the main oxidation intermediates. A reaction scheme involving all these intermediates was proposed. 相似文献
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Kinetic analysis for decomposition of 2,4-dichlorophenol by supercritical water oxidation 总被引:1,自引:0,他引:1
Hyeon-Cheol Lee Jung-Hyun In Jong-Hwa Kim Kyung-Yub Hwang Chang-Ha Lee 《Korean Journal of Chemical Engineering》2005,22(6):882-888
2,4-Dichlorophenol (2,4-DCP), as a halogenated model pollutant, was decomposed by using supercritical water oxidation (SCWO)
in a batch reactor made of Hastelloy C-276. SCWO experiments for 2,4-DCP decomposition were performed in the range of 380–420
°C, 230–280 bar and 0.074-0.221 mol/L H2O2. The effect of oxidant concentration on decomposition rate and efficiency was significant near the critical temperature of
380 °C. However, the role of the oxidant concentration in the SCWO process decreased with an increase in temperature; also,
excess oxidant played a key role in quite significantly decreasing the activation energy of 2,4-DCP oxidation. Variation of
the reaction rate by the change of pressure was negligible even at a near critical temperature. The kinetic rate for the decomposition
of 2,4-DCP in the SCWO process was well described by a simple first-order kinetic and global reaction rate model. From the
SCWO experiments, the various intermediates identified with a GC/MS implied that the first reaction pathway for 2,4-DCP decomposition
led to dimers such as dichlorophenoxyphenols, and the second led to single-ring and ring-opening products. 相似文献
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