Figure - uploaded by Johan Sterte
Content may be subject to copyright.
Effect of time of reflux of pillaring solution on the BET surface area and the BET parameter C of derived La- Al-pillared montmorillonite.
Source publication
Large-pore La-Al-pillared montmorillonite was prepared by reacting montmorillonite with hydrothermally treated mixtures of aluminum chlorohydrate and lanthanum chloride. The large-pore La- Al-pillared montmorillonite is characterized by basal spacings of about 26 A, surface areas of 300-500 m2/g, and pore volumes in the range 0.2-0.3 cm3/g. Large-p...
Contexts in source publication
Context 1
... BET surface areas of these samples are given in Table 1. As seen, the surface areas are all in the range 300-370 mE/g, and no major dependence of the surface area on the time of reflux of the pillaring solution is evident. ...Context 2
... seen, the surface areas are all in the range 300-370 mE/g, and no major dependence of the surface area on the time of reflux of the pillaring solution is evident. The C parameters of the BET equation cal- culated for the different samples are also given in Table 1. The change from negative to positive reflect the change from microporous to, presumably, supermi- croporous materials with increasing time of reflux of the pillaring solution. ...Similar publications
In recent years, semiconductor hollow spheres have gained much attention due to their unique combination of morphological, chemical, and physico-chemical properties. In this work, we report for the first time the synthesis of BiFeO3 hollow spheres by a facile hydrothermal treatment method. The mechanism of formation of pure phase BiFeO3 hollow sphe...
Ti-doped truncated octahedron LiTi
x
Mn2-xO4 nanocomposites were synthesized through a facile hydrothermal treatment and calcination process. By using spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), the effects of Ti-doping on the structure evolution and stability enhancement of LiMn2O4 are revealed. It is found...
Herein, we were synthesized fluorescent carbon quantum dots via facile one-step hydrothermal treatment of mustard seeds (M-CQDs). It showed excellent optical property with fluorescent quantum yield 4.6%. The as-prepared M-CQDs exhibited peroxidase-like mimetic activity and catalyzed the oxidation of chromogenic substrate 3,3‘,5,5‘-tetramethylbenzid...
Developing the superior electrode materials with large reversible capacity, excellent rate capability and long cycling stability for high-performance lithium-ion batteries (LIBs) is highly desirable for electric vehicles and hybrid electronic vehicles. Herein, three-dimensional N-doped carbon (NC)-coated Zn–Sn mixed oxide (ZTO) cubes dispersed on r...
Nanowire/nanorod TiO 2 structures of approximately 8 nm in diameter and around 1,000 nm long were synthesized by alkaline hydrothermal treatment of two different TiO 2 nanopowders. The first precursor was TiO 2 obtained by the sol-gel process (SG-TiO 2); the second was the well-known commercial TiO 2 P-25 (P25-TiO 2). Anatase-like 1D TiO 2 nanostru...
Citations
... Pillaring is a process of preserving a layered system while simultaneously converting it into a heat-resistant micro-or mesoporous material. The basic ideas about the structure of ivory clays were formed in the studies of Pinnaway [12][13], Sturt [14][15][16] and other scientists. ...
The study of the possibility of using modified clinoptilolite as an adsorbent and the adsorption properties of zeolite in the purification of natural gas supplied to gas processing plants from sulfur compounds contained in it is an urgent task. In the experimental study, the adsorbent fraction was chosen as 0.5÷1.0 mm, density - 0.8 g/cm ³ , adsorbent layer height - 600 mm. Optimal conditions are selected in such a way that the pressure in the experimental process is 0.2-5.0 MPa, the amount of mercaptans in the purified natural gas is 50÷400 mg/nm ³ , the temperature is 20÷25°C, the gas flow rate is 0.2÷250°C. 0.25 m/s. Experiments IR spectroscopic studies were carried out on a NikoletIS-10 IR spectrometer in the frequency range 400-5000cm ⁻¹ . The phase composition was studied using a 2DPHASER Bruker X-ray analyzer (CuKa - radiation, 2nd, 20-80 degrees). Electron microscopic images were taken under a Hitachi TM-3000 microscope. Elemental analysis was performed at Oxford Science. The intensity and accuracy of desorption of sulfur compounds adsorbed on clinoptilolite at 250°C, the same results were obtained on NaX zeolite at 320°C. The catalytic activity of regeneration of clinoptilolite at lower temperatures than that of NaX zeolite, although small, made it possible to minimize the decomposition of mercaptans. The purpose of this work is to study the adsorption properties of the sorbent obtained in the process of modifying clinoptilotite during the purification of natural gas from sulfur compounds.
... The presence of acid centers on the surface of their layers as well as on their pillars makes these materials suitable for different reactions of acid catalysis [28,29]. Sterte [30] and McCauley [31] found that the incorporation of lanthanide elements in the preparation of the pillaring agent resulted in a material whose basal spacing was greater than that of conventional materials and have also high thermal stability [32]. ...
Natural Egyptian bentonite clay intercalated with both La and Ni having different molar ratio (La: Ni = 2:1, 1:1 & 1:2) were prepared, saving 5mmole pillar/gm clay, using ultrasonic assistance method. The prepared catalysts were calcined at 450 and then reduced at 400 °C & 600 °C.Characterization of the prepared LaNi-PILC was achieved by X-ray diffraction (XRD), Furrier transform infrared spectroscopy (FTIR), N2 adsorption desorption isotherm (BET) and H2-temperature programmed reduction (H2-TPR). The data confirm the success of intercalation process for both La & Ni in the lamellar structure of bentonite clay. The La: Ni molar ratio affected the specific surface area, Ni crystal size, dispersion and reducibility of the prepared catalyst. The reduction temperature had a great effect on the reactivity and product selectivity during CO2/CH4 reforming at different reaction temperatures (600–800 °C). Where, reduction at 400 °C gives rise to CH4 oxidation reaction (MOR) with formaldehyde as a main product. While reduction at 600 °C enhances the activity and stability for CO2 reforming of methane (CRM) and syngas production (H2/CO ~ 1.19). The most active and stable LaNi1:2-PILC5 catalyst (CO2 and CH4 conversions reached 85% and 90% respectively) is superior with respect to the performance of PILC based catalysts reported in the literatures.
... The second inorganic cation, added in various molar fractions, improves not only the thermal stability but also the adsorptive and catalytic properties of the pillared products (Canizares et al., 1999;Gil et al., 2000). Another appropriate way to overcome such a problem of collapse is the addition of rate earth (Tokarz and Shabtai, 1985;Sterte, 1991;Pires et al., 1998;Mishra and Rao, 2003). While pillared clays are commonly used as catalysts, they are also finding applications as novel adsorbents. ...
This work concerns the application of single and mixed pillared clays in adsorption of inorganic pollutant in the water: the cadmium, the cobalt, and the copper. Adsorption experiments were conducted under various conditions, i.e., pH, contact time, initial concentration, and temperature. A comparison of the adsorption of the three metals onto pillared clays and natural clays suggested that pillared clays had higher adsorption affinity for metals than the unpillared clays. The experimental results indicated that the pillared clays rich on cerium show better properties on Cd²⁺, Co²⁺, and Cu²⁺ adsorption than those without cerium, which made them the promising recycling metals adsorbents. The equilibrium isotherm data were analyzed using the Langmuir and Freundlich isotherm equations. In all cases, the adsorption process fitted the second-order kinetics well, and the isotherm equation due to Langmuir showed good fits with the experimental data.
... Hydrolysis of TiCI, with HCl results in the formation of an octamer (TiO),(OH)f+ which polymerizes to form large molecules of non-uniform size (Sterte, 1991;Del Castillo and Grange, 1993;Khalfallah Boudali et al., 1994). Poorly ordered structures are obtained, showing a high degree of non-pillaring (reflection at 8.3"2 0) and irregular intercalation (broad reflection at lower angles) (Fig. 2). ...
In the present study, BC was measured at three western Himalayan sites (Site-A≈650m, Site-B≈2050m and Site-C≈2600m a.s.l.) during summer and winter seasons of 2014-2016. The objective of this study is to investigate the variability of BC as a function of meteorological conditions and identify potential combustion sources (biomass vs fossil fuel). Furthermore, boundary layer (ABL) height and wind patterns, MODIS fire maps and Concentrated Weightage Trajectory (CWT) analysis were utilized to study potential BC source regions. The average BC concentration at Site-A, B and C were observed to be 4.98±2.79, 4.57±3.54 and 3.01±2.95 μgm-3, respectively. At Site-B, daytime BC was observed to be higher than nighttime, indicating that ABL development and consequent upward transport of pollution from IGP contributed to high BC concentrations in lesser Himalayas. Nevertheless, variable fraction of BC attributable to biomass vs fossil fuel at three stations indicates the effect of transport from IGP overlapped with the effect of mixing with different combustion sources, including local biomass burning practices which modulated BC levels especially at a high-altitude site in winter. On the basis of CWT analysis and MODIS fire counts, emissions from agriculture residue burning in northwestern-IGP impacted the BC aerosols at all monitoring locations, although, based on our in-situ aethalometer measurements, biomass burning fraction of BC remained below 25-30% at Site-A and B. Episodic westerly long-range transport events (from Middle-East, Europe and Central-Asia) can contribute to background BC concentrations especially in wintertime which were, however, in range of sub-μgm-3 levels based on our observations at Site-C.
... In recent reports, a large number of functionalized montmorillonite clay minerals have been explored such as carbon-Mt ( Yu et al., 2008), organically modified montmo- rillonite mineral clay (Abou-El- Sherbini and Hassanien, 2010), surfactant-Mt ( Ma et al., 2016), humic acid-Mt ( Aziz et al., 2015) and so on. Increasing the interlayer spacing of montmorillonite is a practical way to achieve high adsorp- tion capacity, such as with pillared and surfactant modifi- cations (Sterte, 2016;Tong et al., 2010). On this basis, in order to further increase the stability of adsorption, modification with chelating agents comprising active ele- ments such as (-NH 2 ), (-COOH), (-SH) and (-CS 2 ) has been proposed ( Zhu et al., 2016 Gök et al. (2008) examined 8-hydroxy quinolone as a modifier of bentonite for removal of Cu 2+ ions. ...
In this study, a novel, threonine-functionalized montmorillonite (Thr-Mt) was prepared and investigated for the removal of Pb2+ and Cu2+ ions in single-ion and binary-ion systems. The developed composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis, which revealed
that the threonine was successfully intercalated into Mt interlayers. In single-ion systems and on the basis of various parameters, such as pH, contact time, initial concentration and temperature, the adsorption processes in sodium montmorillonite (Na-Mt) and Thr-Mt composites were thoroughly evaluated. The results showed that the Thr-Mt-1.0 composite was the most effective adsorbent, with adsorption capacities of 120 mg/g and 30 mg/g for Pb2+ and Cu2+ (pH = 5), respectively. The negative value of ΔG0 indicates the spontaneous nature of the adsorption process, and the positive value of ΔH0 shows the endothermic nature of the adsorption. The capability of Thr-Mt to
capture aqueous Cu2+ is discussed in terms of surface functional groups intercalated into Mt layers. Surface modification to enhance the adsorption capability toward Pb2+ and Cu2+ reported in this work will provide a facile way for expanding the use of other modified clays to achieve high removal capabilities for toxic cationic species from soil and aqueous media.
... Another appropriate way to overcome such a problem of collapse is the addition of rate earth. Sterte (1991) found that the incorporation of lanthanide elements in the preparation of the pillaring agent resulted in materials whose basal spacing was greater than that of conventional materials. An improvement of the thermal stability of Al-pillared clays was reported by Tokarz and Shabtai (1985), who prepared pillared clay catalysts by first exchanging the clay with Ce 3+ or La 3+ , then exchanging these clays with refluxed, partly hydrolyzed Al 3+ solutions. ...
A series of pillared interlayered clays (PILCs) including Al-, Zr- and Al–Zr-PILC have been prepared and characterized by X-ray diffraction, elemental analyses, N2 adsorption, cationic exchange capacity and IR measurements after n-butylamine adsorption. Cerium introduced in the Zr4 + and/or Al3 + intercalated solution allows for an improvement of the stability and crystallinity of PILC and creates pillared clays with new properties. The resulting materials were used for the synthesis of 1,3-dioxolane. The addition of cerium has a major influence in this reaction.
... El uso de intercambios competitivos (16) y tratamientos con reflujo de la solución pilarizante previo a la intercalación (17,18) son algunas de las técnicas que se emplean para incrementar la estabilidad de las arcillas. Recientemente se reporta un método novedoso de intercalación, donde el polímero Al 13 puede introducirse entre las láminas de una montmorillonita en tan solo 20 minutos a temperatura ambiente. ...
RESUMEN Distintas variables de síntesis se evalua-ron en la modificación por pilarización de dos arcillas esmectíticas con solucio-nes mixtas de Al-Fe-Ce. El efecto del ul-trasonido durante la intercalación de las especies pilarizantes, el tipo de arcilla y la remoción de los óxidos de hierro del mineral natural fueron determinantes en la obtención de materiales activos en la oxidación de fenol en medio acuoso di-luido con una buena selectividad a CO 2 en condiciones experimentales modera-das (20 °C y presión atmosférica). Los sólidos fueron caracterizados por difrac-ción de rayos X (DRX), fluorescencia de rayos X (FRX), reducción a temperatura programada de hidrógeno (RTP-H 2) y mi-croscopía electrónica de barrido (SEM), evidenciando una modificación estructu-ral exitosa en todos los materiales. Con el empleo del ultrasonido se logró la modificación de los sólidos en un tiempo considerablemente menor (20 min.) al proceso tradicional (24 h), conservando las propiedades físico-químicas y cata-líticas de los materiales. Igualmente, se evidenció un efecto de la naturaleza de la arcilla de partida sobre las propiedades químicas y catalíticas del material, así como una mejora al remover los óxidos de hierro del material natural, logrando sólidos con mejor actividad catalítica. Palabras clave: arcilla pilarizada, ul-trasonido, oxidación de fenol, AlFeCe, remoción de hierro.
... The Na + -saturated bentonite was obtained by washing clay several times, first with 1.0 M NaCl and then with deionised water. Lanthana-alumina mixed oxide PILC was prepared 10 . Hydrolysed aluminium chloride was prepared by adding 0.5 M NaOH drop wise to 0.2 M AlCl 3 .6H 2 O by vigorous stirring to an OH/Al ratio of 2.4. ...
This work aims to evaluate the sorbent power of pillared inter layer clay (PILC) for humic acid from aqueous solutions. PILC was prepared from natural bentonite clay with lanthana-alumina mixed oxide pillars and was found to be very effective in removing humic acid from water. Maximum adsorption of 97.3 and 88.8% took place by PILC (pH 3.0) from an initial concentration of 15.0 and 30.0 μmol/l respectively. Lagergren first-order kinetic equation governed uptake process. Electrolyte (NaCl) compresses the diffuse double layer leading to the increased uptake of humic acid; this also showed that van der Waals attraction is an important part of the interactive forces between humic acid and PILC. According to Giles classification, adsorption isotherm may be classified as L-type. The applicability of Langmuir isotherm to PILC-humic acid system was tested. Adsorption capacity 'Qo' (54.32 μmol/g) and binding constant 'b' (0.249 1/μmol) were maximum at 10°C and pH 3.0. Experiments conducted at different temperatures allowed for the calculation of isosteric heat of adsorption, revealing that the adsorption process was exothermic. About 94.6 % can be recovered from the spent clay using 0.01 M NaOH.
... Lanthanum and Cerium Sterte (1991) assessed lanthanum as a rare earth cation that, "most readily formed a complex with aluminium suitable for pillaring". This author was able to produce LaAl pillared montmorillonite with basal spacings of around 26Å and surface areas of 300-500 m 2 /g. ...
This paper presents an overview of the modification of clay minerals by propping apart the clay layers with an inorganic complex. This expanded material is converted into a permanent two-dimensional structure, known as pillared clay or shortly PILC, by thermal treatment. The resulting material exhibits a two-dimensional porous structure with acidic properties comparable to that of zeolites. Synthetic as well as natural smectites serve as precursors for the synthesis of Al, Zr, Ti, Fe, Cr, Ga, V, Si and other pillared clays as well as mixed Fe/Al, Ga/Al, Si/Al, Zr/Al and other mixed metal pillared clays. Biofuels form an interesting renewable energy source, where these porous, catalytically active materials can play an important role in the conversion of vegetable oils, such as canola oil, into biodiesel. Transesterification of vegetable oil is currently the method of choice for conversion to biofuel. The second part of this review focuses on the catalysts and cracking reaction conditions used for the production of biofuel. A distinction has been made in three different vegetable oils as starting materials: canola oil, palm oil and sunflower oil.
... Lanthanum and Cerium Sterte (1991) assessed lanthanum as a rare earth cation that, "most readily formed a complex with aluminium suitable for pillaring". This author was able to produce LaAl pillared montmorillonite with basal spacings of around 26Å and surface areas of 300-500 m 2 /g. ...
