The infrared spectra of the Mg-rich palygorskite from Mingguang,Anhui Province,and Mg-poor palygorskite from Xuyi,Jiangsu Province under heating were investigated.Palygorskite is characterized by two bands at 1 196 and 647 cm-1,which are attributed to the asymmetric stretching vibration of the Si—O—Si group that connects the adjacent inverse SiO4tetrahedrons and the H2O— Mg—H2O stretching vibration in the MgO6 octahedra at the edges of the channels,respectively.The structures of the Mg-rich and Mg-poor of palygorskite are different mainly in the occupied sites of the octahedral cations.The symmetric and asymmetric stretching of perpendicular Si—O—M(VI) appears at 998 cm-1 and 685 cm-1 in the IR spectra of XY-Pal rather than at 987 cm-1and 680 cm-1in the IR spectra of sample MG-Pal.The band at 3 687 cm-1 for Mg-rich palygorskite is attributed to Mg3—OH stretching vibration.Moreover,the band at 865 cm-1is assigned to the CO32-bending vibration of amorphous carbonate.

<正>自Grim(1947)发现粘土矿物能够促进生油母质转化为石油,Brooks(1949)发现酸化粘土能催化异构化等反应以来,"油气生成过程中粘土矿物的催化作用"这一问题备受关注。经过几代研究者的努力,已在两方面取得了广泛共识,包

<正>矿物表面活性是矿物表界面反应中一个重要的指标性参数。如矿物溶解和晶体生长、矿物表面吸附和表面络合反应、矿物表面氧化还原和催化反应,都与矿物表面活性相关。甚至生物矿物界面作用过程中,常用到矿物表面反应性氧基(ROS),其释放能力也与矿物表面活性密切相

A series of nanosized (Fe3-xMnx)1-δO4 (x = 0, 0.2, 0.5, and 0.8) were synthesized for elemental mercury capture from the flue gas. Cation vacancies on (Fe3-xMnx)1-δO4 can provide the active sites for elemental mercury adsorption, and Mn(4+) cations on (Fe3-xMnx)1-δO4 may be the oxidizing agents for elemental mercury oxidization. With the increase of Mn content in the spinel structure, the percents of Mn(4+) cations and cation vacancies on the surface increased. As a result, elemental mercury capture by (Fe3-xMnx)1-δO4 was obviously promoted with the increase of Mn content. (Fe2.2Mn0.8)1-δO4 showed an excellent capacity for elemental mercury capture (>1.5 mg g(-1) at 100-300 °C) in the presence of SO2 and HCl. Furthermore, (Fe2.2Mn0.8)1-δO4 with the saturation magnetization of 45.6 emu g(-1) can be separated from the fly ash using magnetic separation, leaving the fly ash essentially free of sorbent and adsorbed Hg. Therefore, nanosized (Fe2.2Mn0.8)1-δO4 may be a promising sorbent for the control of elemental mercury emission.

A stoichiometric nanosized Mn-Fe spinel (Fe(2.2)Mn(0.8)O(4)) was synthesized using a coprecipitation method. After the thermal treatment at 400 degrees C under air, chemical heterogeneity deriving from the oxidation kinetic difference between Fe(2+) and Mn(2+)/Mn(3+) was observed in (Fe(2.2)Mn(0.8))(1-delta)O(4). XPS and TEM analyses both pointed a Mn enrichment (especially Mn(4+) cation) on the particle's surface. Furthermore, the percent of cation vacancy on the surface increased obviously due to the enrichment of Mn(4+) cation on the surface. As a result, the capacity of (Fe(2.2)Mn(0.8))(1-delta)O(4)-400 for elemental mercury capture was generally much better than those of MnO(x)/gamma-Fe(2)O(3), (Fe(2.2)Mn(0.8))(1-delta)O(4)-200 and Fe(2.2)Mn(0.8)O(4). Furthermore, the saturation magnetization of (Fe(2.2)Mn(0.8))(1-delta)O(4) obviously increased after the thermal treatment under air at 400 degrees C, which made it easier to separate the sorbent and adsorbed mercury from the fly ash for recycling, regeneration, and safe disposal of the adsorbed mercury. Therefore, (Fe(2.2)Mn(0.8))(1-delta)O(4)-400 may be a promising sorbent for elemental mercury capture.

Nonstoichiometric Fe-Ti spinel (Fe(3-x)Ti(x))(1-δ)O(4) has a large amount of cation vacancies on the surface, which may provide active sites for pollutant adsorption. Meanwhile, its magnetic property makes it separable from the complex multiphase system for recycling, and for safe disposal of the adsorbed toxin. Therefore, (Fe(3-x)Ti(x))(1-δ)O(4) may be a promising sorbent in environmental applications. Herein, (Fe(3-x)Ti(x))(1-δ)O(4) is used as a magnetically separable sorbent for elemental mercury capture from the flue gas of coal-fired power plants. (Fe(2)Ti)(0.8)O(4) shows a moderate capacity (about 1.0 mg g(-1) at 250 °C) for elemental mercury capture in the presence of 1000 ppmv of SO(2). Meanwhile, the sorbent can be readily separated from the fly ash using magnetic separation, leaving the fly ash essentially free of sorbent and adsorbed mercury.

A novel magnetic Fe-Ti-V spinel catalyst showed an excellent performance for elemental mercury capture at 100 °C, and the formed HgO can be catalytically decomposed by the catalyst at 300 °C to reclaim elemental mercury and regenerate the catalyst.

Tiantium (Ti) was incorporated into non-stoichiometric Mn–Fe spinel to improve its performance for elemental mercury capture. Although the number of Mn4+ cations on (Fe2TixMn1−x)1−δO4 was less than that on the corresponding (Fe3−xMnx)1−δO4, the number of usable cation vacancies for elemental mercury oxidization obviously increased. As a result, elemental mercury capture by Mn–Fe spinel was generally promoted by the incorporation of Ti. Furthermore, SO2 mainly reacted with ≡FeIII–OH and few Mn4+ cations on the surface reacted with SO2 at lower temperatures (100–150°C), so SO2 poisoning resistance improved at lower temperatures due to the incorporation of Ti. Especially, (Fe2Ti0.5Mn0.5)1−δO4 showed an excellent capacity (4.2mgg−1) for elemental mercury capture in the presence of a high concentration of SO2 at 150°C. Meanwhile, (Fe2Ti0.5Mn0.5)1−δO4 with the saturation magnetization of 30.6emug−1 can be readily separated from the fly ash using magnetic separation, leaving the fly ash essentially free of catalyst and adsorbed HgO. Therefore, nanosized (Fe2Ti0.5Mn0.5)1−δO4 may be a promising candidate catalyst for elemental mercury capture.

In this study,titanomagnetite was synthesized using a soft chemical method. Then,synthetic titanomagnetite was firstly used as a new heterogeneous Fenton catalyst for the decolorization of methylene blue(MB). As compared with magnetite,titanomagnetite showed a more excellent catalytic activity for MB decolorization.Decolorization of MB by heterogeneous Fenton reaction using titanomagnetite was studied using UV-Vis spectra,Fourier transform infrared spectroscopy(FTIR),13C nuclear magnetic resonance spectra (13C NMR),dissolved organic carbon(DOC)and element C analyses. During the decolorization,most of MB removed from reaction solution was degraded and the phase transformation of titanomagnetite did not happen.Although MB was not mineralized,the aromatic rings in MB were destroyed completely.

A series of Fe3-xTixO4(0≤x≤0.78)was synthesized using a soft chemical method.The synthetic Fe3-xTixO4 was characterized using XRD,Mssbauer spectroscopy,TG-DSC and SEM.The results show that synthetic Fe3-xTixO4 was spinel structure and Ti was introduced into its structure.The introduction of Ti into magnetite structure will hinder the further oxidation of magnetite to maghemite and the transition of maghemite to hematite.Then,synthetic Fe3-xTixO4 was used as a heterogeneous Fenton catalyst for the degradation of methylene blue(MB).The experimental result indicates that Fe3-xTixO4 shows an excellent catalytic activity in heterogeneous Fenton reaction.

In this work, titanomagnetite was used as a heterogeneous Fenton catalyst for the degradation of methylene blue (MB). The degradation of MB on synthetic titanomagnetite at neutral pH values was studied in comparison with the adsorption of MB on titanomagnetite using UV-vis, FTIR, and the analyses of element C on titanomagnetite and DOC in reaction solution. Meanwhile, important factors affecting catalytic activity were investigated, that is, titanomagnetite load, H2O2 concentration, and reaction temperature. Titanomagnetite decomposed H2O2 yielding highly reactive hydroxyl radicals, and MB adsorbed on titanomagnetite was degraded. With the increases of titanomagnetite load, H2O2 concentration, and reaction temperature, the degradation of MB was promoted. Moreover, titanomagnetite was proved to be durable with a stable MB removal efficiency after five consecutive cycles.

In this work, a series of Fe3-xTixO4 (0 <= x <= 0.78) was synthesized using a new soft chemical method. The synthetic Fe3-xTixO4 were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Mossbauer spectroscopy, thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The results showed that they were spinel structures and Ti was introduced into their structures.Then, decolorization of methylene blue (MB) by Fe3-xTixO4 in the presence of H2O2 at neutral pH values was studied using UV-vis spectra, dissolved organic carbon (DOC) and element C analyses. Furthermore, the degradation products remained in reaction solution after the decolorization were identified using ionic chromatography (IC), C-13 nuclear magnetic resonance spectra (NMR), liquid chromatography and mass spectrometry (LC-MS). Although small amounts of MB were mineralized, the aromatic rings in MB were destroyed completely after the decolorization. Decolorization of MB by Fe3-xTixO4 in the presence of H2O2 Was promoted remarkably with the increase of Ti content in Fe3-xTixO4 due to the enhancement of both adsorption and degradation of MB on Fe3-xTixO4. (C) 2009 Elsevier B.V. All rights reserved.

In this study,a series of Fe3-xTixO4(0≤x≤0.78)were synthesized using a novel soft chemical method.The synthetic Fe3-xTixO4 was characterized using XRD and FTIR.The results show that synthetic Fe3-xTixO4 has a spinel structure and Ti was introduced into its structure.The introduction of Ti into magnetite structure increases the amounts of hydroxyl(—OH)on the surface of Fe3-xTixO4.Then,the synthetic Fe3-xTixO4 was used as absorbents for the removal of methylene blue(MB)from solution.The experimental results indicate that with the increase of Ti in Fe3-xTixO4,the absorption of MB on Fe3-xTixO4was promoted remarkably and the absorption reached the equilibrium within 0.5 hour.

Kaolinite/formamide intercalation materials are characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FT-IR), Raman spectroscopy and 1H magic angle spinning nuclear magnetic resonance spectroscopy (1H MAS NMR). The d(001) spacing of kaolinite treated with formamide is 1.020nm, which is larger than that of the original clay. The 1H MAS NMR graphs show that the proton chemical shifts of the inner hydroxyl and inner surface hydroxyl of kaolinte are δ-1.3 and δ2.4 respectively. After formamide intercalation, the proton peaks of the inner surface hydroxyls shifted to high-field with δ2.3, the proton peak of the inner hydroxyl shifted to δ-0.3 toward low-field. In the hydroxyl stretching vibration region of Raman spectrum, the formamide intercalation resulted in the decrease of the intensities of kaolinite inner surface hydroxyl bands at 3699cm-1,3682cm-1, 3665cm-1 and 3642cm-1, and the appearance of additional bands at 3610cm-1,3628cm-1. In the NH stretching region of FT-IR spectrum, two bands are observed at 3336cm-1 and 3466cm-1 corresponding to the two types of the hydrogen bonds between formamide and kaolinite. In the carboxyl stretching region, an additional band at 1667cm-1 is assigned to C=O group that bonded to the inner surface hydroxyl of kaolinite.

The catalytic decomposition kinetics of phenol with hydrogen peroxide and sulfide mineral pyrrhotite (Fe1-xS) were investigated by using batch experimental technique under normal temperature. Results shown that as solution pH in range 3.8-5.9 phenol can be decomposed completely with the kinetic rate k=4.0-212 h-1(g/L)-1, which is higher than that with hydrogen peroxide and iron oxide minerals, and be comparable to that with Fenton reagent. Else the solid catalysis pyrrhotite is easy to be separated from solution and reusable. The both of analytic results of violet spectra and concentrations of Fe(II) and Fe(Ⅲ) in reactive solution suggest that the processes of phenol decomposition is similar to Fenton reaction, the phenol is first transferred to polyphenols and then decomposed to carboxylic acid with TOC mineralizing degree 50%-58% depending solution pH.

The adsorption of pentachlorophenol (PCP) onto quartz, kaolinite, illite, montmorillonite and iron oxides has been investigated by batch equilibrium techniques. The pH-dependent isotherms are curves with peak values, the position of which is at about pH = 5-6 depending on the mineral species. Based on distribution of both speciation of surface hydroxyls on minerals and PCP in solution a surface reaction model involving surface complexation and surface electrostatic attraction is presented to fit the pH-dependent isotherms, and both reaction constants are calculated. The results show that on quartz and phyllosilicate minerals the predominant adsorption reaction is surface complexation, meanwhile both of surface electrostatic attraction and surface complexation are involved on the iron oxide minerals. The reaction constants of surface electrostatic adsorption are usually one to three orders in magnitude, larger than that of surface complexation. The concentration-dependent isotherms can be well fitted by Langmuir equation with the correlation coefficient R > 0.93 for kaolinite and iron oxides. The maximum adsorption is found in the order: hematite > lepidocrocite > goethite > kaolinite > quartz > montmorillonite = illite, which can be interpreted by consideration of both reaction mechanism and surface hydroxyl density. The significant adsorption of PCP onto mineral surfaces suggests that clay and iron oxide minerals will play an important role as HIOCs are adsorbed in laterite or latertoid soil, which is widespread in South China.

Catalytic oxidation of phenol by H2O2 with goethite and lepidocrocite was investigated in an aqueous system at pH=3～6 under normal room temperature.The results of ultraviolet spectra and TOC analysis of products suggest that when solution pH4 the phenol was completely decomposed to carboxylic acids and about 50%～60% of TOC was mineralized.However as solution pH was in range of 4～5 the phenol was catalyzed to polyphenol such as catechol and hydroquinone,but was basically not mineralized for the reaction system with either goethite or lepidocrocite.When pH5 the phenol in solution was neither transferred to polyphenol nor be mineralized.Kinetic rate calculation shown that the rate constant of phenol decomposition in presence of lepidocrocite is usually larger than that of goethite under same condition,and largest rate was found at about pH=3.8 in presence of lepidocrocite.Actually the rate constants were depended on both of homogeneous and heterogeneous catalytic reaction in the system.Former depends on the contents of ΣFe=Fe(Ⅱ)+Fe(Ⅲ)in solution solved by H2O2 from iron oxides,which increase as solution pH descents.Later depends on the surface characteristics of iron oxide.

The relationship between the kinetic rates of catalytic oxidation of phenol,by H_2O_2 with goethite,lepidocrocite,hematite and magnetite in aqueous solutions at pH=3-6 under normal room temperature,and the pH values of solutions has been investigated in this study.The spectrum characteristics of the decomposing products were determined by using ultraviolet spectrometry.The experimental results indicate that the constant k values for kinetic rates of the catalytic decomposition of phenol in various reaction systems are decreased subsequently from the lepidocrocite reaction system,to the magnetite,the goethite,and to the hematite reaction system.The biggest k value for kinetic rate of the catalytic decomposition of phenol is obtained in the lepidocrocite reaction system at pH value of 3.8 for the solution.The ultraviolet spectra and TOC(total organic carbon) analysis of the decomposing products suggest that the phenol was completely decomposed to carboxylic acids and about 50%-65% of TOC was mineralized in the lepidocrocite,the magnetite,and the goethite reaction systems respectively at pH values of 3-4 for the solutions.However,most of phenol was transformed to polyphenols,such as catchol or hydroquinone,only minor was degraded to hexalene acid in the hematite reaction system at pH value of 3.25 for the solution.When the pH values of solutions are in range of 4-5,the phenol was only transferred to polyphenol such as catechol and hydroquinone,and TOC was basically not mineralized for the reaction system of goethite.When pH values of solutions are larger than 5,the phenol in solution was neither transferred to polyphenol nor be mineralized in all iron oxide reaction systems.

Sialon was synthesized from kaolinitepolyacrylamide intercalation compound by carbothermal reduction and nitridation(CRN) processing at 1 400 ℃.Kaolinite-carbon mixture was treated at the same condition as the intercalation compound for comparison.XRD,FT-IR,and TEM were used to study the phases,structure and morphology of products.In the CRN product from the intercalation compound,β′-Sialon and O′-Sialon are main phases.Oxides were reduced without cristobalite being detected.In addition,in the product from the mixture,the phases are more complex with lower content of β′-Sialon than in the intercalation compound CRN product.The in-situ carbothermal reduction and nitridation processing of kaolinite is a novel and effective method of Sialon synthesis.The layered nano-structure of the intercalation compound is the main factor of highly effective carbothermal reduction and nitridation processing.