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1.
低成本吸附剂稻壳灰对Cr(Ⅵ)去除机制的谱学表征   总被引:1,自引:0,他引:1  
以低成本稻壳灰作为吸附剂,使用FTIR,SEM,XPS,XRD,XRF等分析手段,研究稻壳灰对Cr(Ⅵ)的去除机制。FTIR研究表明酰胺Ⅱ带,Si—O—Si,O—Si—O等在Cr(Ⅵ)去除过程中有一定贡献。由SEM图片清晰可见:吸附Cr(Ⅵ)后,稻壳灰表面分布有众多的光亮沉积物。XPS图谱证明:稻壳灰的主要组成元素为C,N,O,P和Si;C元素的存在状态以醛酮类为主,含C官能团与Cr(Ⅵ)发生了配位反应;N元素以—NH2形态为主,Cr(Ⅵ)可能以静电作用与含N基团结合,并以物理吸附为主;Si的存在以Si—O为主,含Si官能团可能与Cr(Ⅵ)发生了配位反应。XRD分析结果表明:谱图中出现的峰是典型的SiO2特征峰;稻壳灰的结晶度增加,表明稻壳灰与Cr(Ⅵ)形成了具有晶体结构的金属化合物。XRF研究发现,K,Na,Mg和Ca的元素含量在吸附前后有所变化,另有两种新元素出现,这说明吸附过程存在离子交换机制。所有这些皆表明:各种官能团在Cr(Ⅵ)去除过程中的角色各不相同,无机微沉淀机制、氧化还原机制、表面络合机制、离子交换机制等是稻壳灰去除Cr(Ⅵ)的主要途径。这可以为吸附技术的实际应用提供理论支持。  相似文献   

2.
采用溶胶凝胶法制备了Ti1-xCrxO2±δ体系系列样品.利用扫描电子显微镜(SEM),X射线光电子能谱(XPS),粉末X射线衍射分析(XRD)方法研究了Ti1-xCrxO2±δ系列样品的颗粒尺寸、形貌、组分化学态、相关系和固溶区范围;并利用超导量子干涉磁强计对样品的磁性能进行了研究.采用Rietveld结构精修的方法研究了Cr的不同掺杂量对TiO2晶体结构的影响,研究表明,1000℃烧结的样品的固溶区范围是x=0—0.03,为金红石单相;随着Cr掺杂量的增加,金红石相晶胞参数规律性地减小;当x>0.03,为金红石相和CrO2相两相共存.综合XRD和磁性测量结果,500℃烧结的样品的固溶区范围是x=0—0.02,为锐钛矿单相;随着Cr掺杂量的增加,锐钛矿相晶胞参数规律性地减小;当x≥0.04,为锐钛矿相和绿铬矿相(Cr2O3)两相共存.XPS实验结果表明,500℃和1000℃退火的样品中Cr都是以Cr 3和Cr 6两种化学态存在,1000℃烧结的样品中可能有更多的Cr3 转化为Cr6 .根据M-H和M-T曲线的测试结果发现,本文500℃烧结的Ti1-xCrxO2±δ体系样品当x=0—0.02时,为室温铁磁性.当x≥0.04时,由铁磁相和顺磁相所组成,在低温下有较强的铁磁性;室温下主要是顺磁相,铁磁相只占据很小的体积分数.  相似文献   

3.
纳米铁广泛用于水中重金属离子的去除,但由于其易团聚的特性,在地下水中迁移性差,使其修复效果降低。氧化石墨烯具有吸附重金属的作用,但由于其表面带有负电荷,对带负电的高价铬(Cr_2O_7~(2-),CrO_4~(2-))吸附作用较弱。以氧化石墨烯(GO)为载体,采用液相还原法制备的氧化石墨烯负载纳米铁(rGO-nZⅥ),在改善纳米铁的分散性的同时,利用nZⅥ将带负电的高价铬(Cr_2O_7~(2-),CrO_4~(2-))还原为带正电的三价铬(Cr~(3+)),增强了氧化石墨烯对其吸附的性能。利用XRD和TEM对制备的rGO-nZⅥ进行表征,表明制备的rGO-nZⅥ近似球形,粒径为20~100nm;零价铁负载在GO表面。应用rGO-nZⅥ处理Cr(Ⅵ)污染的地下水,Cr(Ⅵ)的去除效率可达到100%,材料的最佳投加量与Cr(Ⅵ)浓度呈线性正相关。采用X光电子能谱(XPS)分析铬和铁的存在形态,并通过XPAPEAK41分峰后证实,Cr(Ⅵ)首先被还原为Cr(Ⅲ),进而生成Cr(OH)3吸附到材料表面。由XPS图看出,经24h反应,69.8%的Cr(Ⅵ)转化为Cr(Ⅲ)吸附到材料表面,此时仍具有Fe0的峰,证实材料具有很强的还原吸附铬的能力,且仍具有缓慢释放电子的能力,有利于后续长时间的修复。该结果对于利用rGO-nZⅥ处理地下水Cr(Ⅵ)污染具有重要的理论意义和实用价值。  相似文献   

4.
FTIR和XPS对沸石合成特性及Cr(Ⅲ)去除机制的谱学表征   总被引:1,自引:0,他引:1  
以粉煤灰为原料,采用优化的水热晶化法合成沸石,使用XRD,SEM和ζ电位分析沸石产品的组成特性,借助FTIR和XPS等揭示废水中Cr(Ⅲ)的去除机制。合成产品主要为NaP1型沸石,在pH值8~12区间内,ζ电位由-8.72mV降到-24.46mV。准二级方程和Langmuir等温线对试验的拟合效果更好,理论饱和吸附量为33.557 0mg.g-1。FTIR图谱表明—OH和Si—O类官能团在反应过程中有重要贡献。XPS全谱发现:结合能576.45eV为Cr(2p3/2)的特征峰,揭示了吸附过程的有效性。吸附Cr(Ⅲ)后,沸石中Si—Si和Si—O对应的结合能增加了0.25和0.60eV,含Si官能团可能与Cr(Ⅲ)发生了配位反应。O(1s)的结合能在反应后变得更低。这些证据表明:沸石对Cr(Ⅲ)的去除过程是物理吸附和化学吸附共同作用的结果。  相似文献   

5.
不同表面状态镀锡钢板铬酸盐钝化膜中铬元素的XPS分析   总被引:3,自引:0,他引:3  
用x射线光电子能谱(X-ray photoelectron spectroscopy,XPS)分析的方法,对铬酸盐钝化镀锡钢板的正常表面及缺陷点处铬元素的含量、价态以及由铬元素组成的化合物进行了研究.用超声波的方法对铬酸盐钝化镀锡钢板进行处理后,研究了超声波处理对缺陷处的铬元素的含量、价态的影响.结果表明,钝化膜中主要含有Cr,O,sn元素.镀锡铬酸盐钝化膜中正常表面的铬元素主要是以Cr(OH)3,Cr单质以及Cr2O3的形态存在.在对镀锡板表面进行阴极电解钝化的过程中,Cr(Ⅵ)发生了转化,价态降低.在缺陷处,除了有Cr(OH)3和Cr2 O3以外,还有微量的Cr(Ⅵ)存在.在缺陷处铬元素的含量低于正常表面,在超声波清洗处理后,缺陷处铬元素的含量明显低于不经超声波清洗的含量.施加的超声波因产生强烈的洗脱作用,使吸附在缺陷处的微量的Cr(Ⅵ)消失.  相似文献   

6.
采用热重分析与红外色谱分析(TGA-FTIR)相结合的方法,研究了NiO载氧体与高浓度CO与H_2S混合气的还原、硫化反应性。实验结果表明,随反应循环数增加,NiO载氧体的平衡态转化率基本不变,但反应速度减小。FTIR检测得气态产物主要由CO_2、COS、CS_2、SO_2组成,而且XPS、XRD分析结果显示硫化产物Ni_3S_2的质量分数随循环数增加而减小。SEM表明还原态NiO载氧体颗粒表面呈现烧结现象。  相似文献   

7.
X射线光电子能谱在配合物研究中的应用及其研究进展   总被引:1,自引:1,他引:1  
通过研究内层电子结合能及其氧化态的变化,X射线光电子能谱(XPS)可以鉴别元素种类和价态、测定元素的相对含量、了解中心离子与配位原子的相互作用和验证量子化学理论.XPS已成为研究配合物中配位位点、电荷分配和配合物结构的有力工具.  相似文献   

8.
粉煤灰地聚合物固封Cr3+的FTIR和XPS研究   总被引:1,自引:0,他引:1  
采用傅里叶变换红外光谱(FTIR)和X射线光电子能谱分析(XPS)研究了粉煤灰地聚合物固封Cr3 的机理。含Cr的污泥由人工合成,主要成分是Cr(OH)3。浸出试验采用ICP-AES方法,测试了固封Cr3 前后,粉煤灰地聚合物中Al和Si的浸出量;研究结果表明,掺入含Cr的污泥后,粉煤灰地聚合物中Si和Al元素的浸出量较不掺污泥时减少了,且浸出Si元素减少的幅度比浸出Al元素降低的幅度要大。FTIR结果显示,Cr3 的掺入削弱了粉煤灰地聚合物主峰的强度,增加了Si—O—Si和Al—O—Si的振动波数;XPS测试结果表明,O(1s),Si(2p)和Cr(2p)的结合能都有不同程度的改变,而Al(2p)的结合能几乎没有发生变化;结果揭示Cr3 参与了粉煤灰地聚合物中硅酸结构的聚合,粉煤灰地聚合物固封Cr3 ,不仅仅只是物理性的包裹作用,而且主要是化学反应的结果。  相似文献   

9.
采用硅烷偶联剂对凹凸棒土进行表面接枝改性,并通过熔融共混技术在双螺杆挤出机上制备了有机化凹凸棒土/尼龙6复合材料.利用X射线光电子能谱(XPS)、红外光谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)对改性结果和复合材料的晶体结构和微观相貌进行表征.结果表明:改性后凹凸棒土表面Si,N,C元素的质量分数提高,结...  相似文献   

10.
无机粒子杂化聚酰亚胺(PI)薄膜具有优良的耐电晕特性,广泛用于变频电机中,文章首先用偶联剂处理过的超细氧化铝粉掺杂聚酰胺酸(PAA)制备了不同氧化铝含量的聚酰亚胺杂化膜.通过傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、电感耦合等离子发射光谱(ICP)、重量法、热失重(TG/空气气氛)等测试方法对制备的不同Al2O3含量杂化聚酰亚胺薄膜的无机成分进行了定性和定量分析.结果表明:FTIR和XPS能很好地对杂化膜进行定性分析,FTIR主要对材料的结构进行分析从而推断出其可能的成分,而XPS则主要得到材料所含各元素信息,它具有操作简单,重复性好等优点;通过研究内层电子结合能及其氧化态的变化,XPS可以鉴别元素种类和价态、测定元素的相对含量.XPS和TG的实测值和理论值相差较大,相对标准偏差(RSD)很大,其中,XPS的RSD值大于5.0%,而TG的RSD值也都大于2.0%,只能对杂化膜进行半定量分析.而ICP和重量法的实测值和理论值相差较小且相对标准偏差(RSD)很小,它们的RSD)值均小于1.0%,能进行精确的定量分析,其中重量法的实测值最接近理论值,但只能用于单一无机组分的分析;而ICP法最精确且可以对多无机组分的复合物进行分析,它有简便、快速、灵敏度高、准确性好、可多元素同时测定,且对环境污染小等优点.由上面的结论可以得到一种分析复合材料中的无机成分的方法:首先,用FTIR和XPS对复合材料进行定性分析;然后,以XPS半定量分析结果作为参考,用重量法(单一组分)和ICP法对复合材料进行精确的定量分析.  相似文献   

11.
By reducing potassium chromate with hydrogen and then calcining the obtained intermediate at high temperature, the ultra-fine chromia (Cr2O3) powder with a mean diameter of 0.3 μm was successfully prepared. Using scanning electron microscopy (SEM) and XRD, the chromia products were characterized. Through XPS, TG-DSC, FT-IR, XRD and chemical analysis, the reaction mechanism was explored. The results revealed that, the intermediate from reducing potassium chromate with hydrogen consists of Cr(OH)3·nH2O, CrOOH, KCrO2 but the composition of the intermediate changes with the reduction temperature and time. Typically, the potassium content in the intermediate ranges approximately from 0.7% to 8% by weight and the chromium content from 50% to 57% by weight. It was also found that, just by calcining the intermediate in the presence of oxygen can the potassium in the intermediate be completely removed from the final chromia product.  相似文献   

12.
The aim of this work was to investigate the photocatalytic (PC) reduction of potassium chromate by Zn-doped TiO2/Ti film catalysts. The film catalyst was prepared by plasma electrolytic oxidation method in H2SO4 solution with different dosages of ZnSO4. The composition and structure of the film catalysts was studied by XRD, SEM and EPMA. The removal rate of potassium chromate was investigated under the conditions of the different dosages of ZnSO4 and the initial concentration of chromate potassium, and the reductive product during the PC reduction process was analyzed. The results showed that the film catalyst was composed of anatase TiO2 and rutile TiO2 with the porous structure. When the dosage of ZnSO4 was 0.2 g/L, the film catalyst presented the highest catalytic activity, which related to the amount and the crystal grain size of anatase TiO2 in the film. The PC reduction of potassium chromate by the film catalyst obeyed the pseudo-first-order kinetic equation. The UV-vis spectrum and XPS analyses proved that chromate Cr(VI) was reduced to Cr(III), which existed in the form of insoluble Cr(OH)3.  相似文献   

13.
Aqueous chromate sorption on suspended magnetite in the presence of gamma irradiation has been evaluated. Kinetics of chromate removal was evaluated using Lagergren's absorption model. Chromate removal with respect to the accumulated dose followed a Lagergren's pseudo-first-order kinetic model. A comparison of kinetics of chromate removal with respect to total accumulated dose for gamma irradiation experiment vis-à-vis with respect to time of treatment for different isothermal interactions has been undertaken. Rate constants indicate that the chromate removed per minute in isothermal equilibration at 80 °C is comparable to the chromate removed per kilogrey of gamma irradiation received. There is a redox interaction between the chromate and the ferrous of the suspended magnetite which was confirmed by X ray photo electron spectroscopy (XPS) analysis. This process reaches a saturation much before the consumption of entire ferrous ions of magnetite, indicating a passivating nature of the product. The effect of radiation on both chromate solution and dispersed magnetite to alter the redox process could be ascertained. Gaussian–Lorenzian peak fittings to the XPS data have been carried out to evaluate the chemical composition of the deposited chromium and the resultant change in the chemical composition of the iron in the oxide lattice. This indicated that the magnetite equilibrated with chromate under gamma irradiation resulted in a different surface composition as compared with the one obtained in absence of gamma irradiation. XPS data indicated the presence of hydroxyl group and oxide group attached to both iron and chromium moieties in case of irradiation, whereas only oxide group was seen with only temperature treatment.  相似文献   

14.
纳米TiO2的表面能态及光生电子-空穴对复合过程的研究   总被引:9,自引:1,他引:8  
以液相法制备了水溶态纳米TiO2,并通过X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶红外光谱仪(FTIR)对纳米TiO2的结构和组成作了细致分析.并对其紫外-可见光谱(UY-Vis spectrum)和荧光发光光谱(PL spectrum)进行了分析.结果发现纳米TiO2呈现较好的锐钛矿型,平均粒径为5 nm.水溶态纳米TiO2由于吸附而在表面形成了Ti-OH和Ti-H2O的表面态,其能级位于其价带以上约0.6和0.54eV;500℃热处理后样品的表面吸附水基本消失,但OH-仍然存在,同时在纳米TiO2晶格中出现了氧空位,其能级位于价带以上3.13 eV.对于水溶态纳米TiO2,表面复合是电子-空穴对的主要复合过程;热处理后的样品,由于表面态遭到破坏,粒子半径变大,直接复合成为电子-空穴对的主要复合过程,同时还伴随有通过氧空位的间接复合和通过Ti-OH的表面复合.  相似文献   

15.
In this work we study the changes induced on the structure of a smectite clay by chemical acid activation with HCl using X-ray diffractometry (XRD) and transmission Mössbauer spectroscopy (TMS) techniques. By XRD we were able to determine the mineralogical composition of the clay samples and measure the changes in the interplanar distance associated to the structural modifications in the clays. We measured a reduction in the interplanar distance and reflection intensity as the acid concentration in the activation process increased. TMS allowed us identify and characterize the structural sites occupied by ferric and ferrous iron cations. In addition, we were able to monitor the effects caused by the chemical acid activation on the valence state of the iron cations that occupy these structural sites in the clay. For the treatment at low acid concentration, keeping time and temperature of activation constant, our results showed a strong effect on the ferrous and ferric iron sites, reducing and increasing their adsorption relative areas respectively.  相似文献   

16.
Ultra fine silicon-doped tin oxide composite powders have been synthesized using an advanced ultrasonic spray method. The SEM pictures revealed a particle size of about 100 nm. The structure and composition of the samples have been analyzed by XRD, FTIR, EDX and XPS. According to the XRD results, the as-prepared materials exhibit the rutile structure, with lattice parameters changing to some extent as the silicon dopant content increased. FTIR spectra showed SiO2 peaks and intensities increased in proportion to the nominal and EDX composition. XPS data were analyzed in detail and confirmed the Sn–O–Si bond exists in the composite.  相似文献   

17.
β-RbNd(MoO4)2 microplates have been prepared by the multistage solid state synthesis method. The phase composition and micromorphology of the final product have been evaluated by XRD and SEM methods. The electronic structure of β-RbNd(MoO4)2 molybdate has been studied employing the X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). For the molybdate, the XPS core-level and valence-band spectra, as well as XES bands representing energy distribution of the Mo 4d- and O 2p-like states, have been measured. It has been established that the O 2p-like states contribute mainly to the upper portion of the valence band with also significant contributions throughout the whole valence-band region. The Mo 4d-like states contribute mainly to a lower valence band portion.  相似文献   

18.
Cu-doped zinc oxide (ZnO:Cu) films were deposited on p-Si (1 0 0) substrates at 200 °C under various oxygen partial pressures by using radio frequency reactive magnetron sputtering. The properties of the films were characterized by the X-ray diffraction spectroscopy (XRD), energy dispersive spectrometer, X-ray photoelectron spectroscopy (XPS) and fluorescence spectrophotometer with the emphasis on the evolution of microstructures, element composition, valence state of Cu, optical properties. The results indicated that the properties of ZnO:Cu films were significantly affected by oxygen partial pressures. XRD measurements revealed that the sample prepared at the ratio of O2:Ar of 15:10 sccm had the best crystal quality among all ZnO:Cu films. XPS analysis results suggested that the valence of Cu in the ZnO films was a mixed state of +1 and +2, and the integrated intensity ratio of Cu2+ to Cu+ increased with the increment of oxygen partial pressure. The photoluminescence measurements at room temperature revealed a violet, two blue and a green emission. We considered that the origin of green emission came from various oxygen defects when the ZnO:Cu films grew in oxygen poor and enriched environment. Furthermore, the influence of annealing atmosphere on the microstructures and optical properties of ZnO:Cu films were discussed.  相似文献   

19.
A novel environment-friendly conversion coating for Mg-8.5Li alloy was obtained by immersing in a solution of molybdate. The concentration of ammonium molybdate and the addition of potassium permanganate were discussed in this experiment. The surface morphology of the conversion coatings was observed by scanning electron microscopy (SEM), and the chemical composition was investigated by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Mg-8.5Li alloy and conversion coatings were investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The results showed that the coatings with cracked morphology were homogeneous and uniform. The conversion coatings were mainly composed of metal-oxide as detected by XPS. The results of electrochemical measurement and weight loss measurement revealed that the molybdate conversion coating had better corrosion resistance than bare alloy and chromate conversion coating, and the molybdate/permanganate conversion coating had lower corrosion current density and higher coating resistance than the molybdate conversion coating.  相似文献   

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