Papers by Keyword: Montmorillonite

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Authors: S. Payungsak, Atchana Wongchaisuwat, Ladda Meesuk
Abstract: This article involves the use of [Ca (2,2′-bipyridine)3]2+-intercalated montmorillonite as a potentiometric sensor to measure anions in aqueous solution. The [Ca (2,2′-bipyridine)3]2+-intercalated montmorillonite was prepared by modification of an in situ solid-solid reaction, between natural Ca (II)-montmorillonite and 2,2′-bipyridine at a molar ratio 1:3. The formation of [Ca (2,2′-bipyridine)3]2+- in the interlayer space of montmorillonite was confirmed by powder X-ray diffraction (XRD) and the existence of 2,2′-bipyridine was confirmed by the C:N ratio of the product compared with that of the 2,2′-bipyridine molecule. The potentiometric sensor was constructed by mixing [Ca (2,2′-bipyridine)3]2+-intercalated montmorillonite with artificial graphite, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) in an appropriate ratio. It was found that the sensor had higher sensitivity to S2- rather than other anions, graphs of log [S2-] vs voltage (mv) gave a slope 30.0 which was closed to theoretical value, 29.5. Activity of the [Ca (2,2′-bipyridine)3]2+ sensor was verified by using sensor made from Ca (II)-montmorillonite as a reference. Reproducibility and precision of the electrode were also determined.
Authors: Azlin Fazlina Osman, Abdulkader M. Alakrach, Hussein Kalo, Omar Sabbar Dahham, Mohd Mustafa Abdullah Al Bakri
Abstract: The viability of metallocene linear low density polyethylene (mLLDPE) nanocomposites is being investigated as a new material for biomedical application. The effect of filler loadings on the ambient and in vitro (after being exposed in oxidizing condition, 37°C) mechanical properties was studied. We observed that, the mLLDPE nanocomposites have higher mechanical property values as compared to the neat mLLDPE. Furthermore, these properties were less affected by the in vitro conditions. The best ambient and in vitro mechanical properties were achived when 3wt% of organically modified MMT (organo-MMT) was added into the mLLDPE. It was postulated that the presence of MMT layered structure introduced a more tortous path for the diffusing of oxidant molecules, thereby decreasing their permeability towards mLLDPE molecular chains. The smaller amount of oxidants entering the molecular chains resulted in greater retention of mechanical properties when tested in vitro. This preliminary biostability studies show promising properties of the mLLDPE nanocomposite which possess the potential to be further developed for biomedical devices.
Authors: Siti Norasmah Surip, A.H. Ismail
Abstract: In this new world, polymer nanocomposites have developed to be one of the latest evolutionary steps in the polymer technology, besides showing a great deal to become the most versatile industrial advanced materials. In comparison with conventional composites, nanocomposites demonstrate significantly higher levels of mechanical performance with less content of particles. Thus, this study was carried out to investigate the effect of nano& micron size of clay particles to mechanical properties of epoxy adhesive. Three types of mechanical test were performed; tensile, impact and shear test. The result shows that the tensile strength was increase by using micron clay while shear and impact strength was increase by using nanoclay. The dispersion of clay in the epoxy adhesive is very important because it will affect the mechanical properties of epoxy adhesive itself. The function of clay to enhance the properties of epoxy adhesive is more effective when the clay is well dispersed. FESEM shows that the nanoclay was well dispersed in the epoxy adhesive while micron sized clay was partially intercalated.
Authors: Ming Kuen Chang, Hsin Hong Hsieh, Siou Jyuan Li
Abstract: Intrinsically conductive polymer-Polyaniline had high conductivity and many other properties, such as environmental stability and rather simple synthesis. In addition, doping with organic acids could enhance its processing, so it had wide range of applications, such as solar cells, antistatic and electromagnetic interference shielding. In this study, the organic amine 1-Dodecylamine (DOA) modification of sodium montmorillonite (NA+-MMT), and conducting polymer / layered silicate salt nanocomposites (PANI-PTSA/DOA-MMT) had been prepared by doping aniline with organic acid (PTSA), then added organic clay. The thermal, electrical properties and EMI effects of nanocomposites had discussed by XRD, TEM, EMI, TGA analysis, conduction measure and EMI tested. The results indicated the organo-clay interlayer distance expanded from 1.29 to 1.8 nm, and DOA-MMT dispersed in the material, that formed an exfoliated nanocomposite. The thermal stability of nanocomposites depended on content of DOA-MMT, material had the better thermal stability when DOA-MMT load was 5 wt. %. The nanocomposites had the best conductivity when DOA-MMT load was 1 wt. % as well as the electromagnetic shielding effectiveness was increase with increase in conductivity. In addition, the electromagnetic shielding of nanocomposites also depended on thickness and frequency of electromagnetic wave, the electromagnetic shielding was increased with increase in thickness and frequency.
Authors: Hong Yan Xu, Xing Tong Chen
Abstract: Al-pillared montmorillonites (Al-MMT) were synthesized from naturally occurring sodium montmorillonite through exchange of interlamellar ions with hydroxyalumina polycations. Furthermore, Powder X-ray diffraction (XRD), Fourier transformation infra-red spectra (FTIR), Thermogravimetric analysis (TG), and differential scanning calorimetry (DSC) were applied in order to study the themal stability, hydrothermal stability and synthesis mechanisms of pillared materials. The Al-MMT are thermally stable and hydrothermal stability up to700°C. X-ray diffractograms of Al-MMT calcined at 700 0C show a sharp and intense d001 peak, corresponding to a basal spacing of 1.66nm. Until calcinations at 8000C, the pillared clays generally retain their structural ordering as evidenced by a broad basal (001) peak, which is an indication that the layer structure lost some long-range ordering. In a 100% steam flow under atmospheric pressure at 7000C, the characteristic d001 spacing of Al-MMT decreases from 1.83nm to 1.71nm, intensity of basal peak reduced by58%. However, after hydrothermal at 8000C, the basal (001) peak is not observed, indicating a complete structural collapse. Synthesis mechanisms for Al-MMT are established. Some of tetrahedral silicons or aluminums inverse towards gallery to react with pillaring agents and yield Alp-O-AlsⅣ or Alp-O-Sis bridges which would firmly fix the pillars to the host clay.
Authors: Shi Yong Wei, Xu Hong Deng
Abstract: Two hydroxy-aluminum pillared montmorillonites (Al-Mt-20 and Al-Mt-80) were prepared at 20°C and 80°C, respectively. The adsorption characteristics for fluoride by Al-Mt-20 and Al-Mt-80 were investigated. Results showed that the d (001) spacing of montmorillonite in Al-Mt-20 and Al-Mt-80 was 1.392 and 1.481 nm, respectively. The optimum pH value for fluoride adsorption was about 4-5. At pH 4.8, the Langmuir adsorption capacity (qmax) for fluoride of Al-Mont-20 and Al-Mont-80 was 7.12 mg/g and 9.78 mg/g, respectively. The adsorption data for fluoride by Al-Mont-20 and Al-Mont-80 could be fitted by Langmuir model (R2 =0.982-0.987), indicating that Langmuir model is suitable to fit the fluoride adsorption of Al-Mont-20 and Al-Mont-80.
Authors: Ya Hong Zhao, Li Wang
Abstract: The carboxymethylcellulose/montmorillonite (CMC/MMT) nanocomposite was prepared by a solution intercalation technique. The effects of contact temperature, the initial pH value of dye solution, contact time and the initial dye concentration on the adsorption capacitiy of CMC/MMT nanocomposite for Congo red (CR) were investigated. The adsorption kinetics and isotherms of nanocomposite were also studied. The results indicated that with the contact temperature increasing and the initial pH value decreasing, the adsorption capacity of the CMC/MMT nanocomposite increased. Compared with the adsorption capacity of CMC (62.42 mg/g), the nanocomposite exhibited the higher adsorption capacity (161.08 mg/g). The adsorption behaviors of CMC/MMT nanocomposite showed that the adsorption kinetics and isotherms were in good agreement with pseudo-second-order equation and the Langmuir equation.
Authors: Xiao Li Wang, Lixiang Wang, Huijuan Wang
Abstract: The corn stalk/montmorillonite(CS/MMT) nanocomposite was prepared by a solution intercalation technique. The effects of the initial pH value of Pb2+ solution, contact time and the dosage of adsorbent on the adsorption capacitiy of CS/MMT nanocomposite for Pb2+ were investigated. The adsorption kinetics and isotherms of nanocomposite were also studied. The results indicated that with the initial pH value increasing, the adsorption capacity of the CS/MMT nanocomposite increased. Compared with the adsorption capacity of CS (6.32 mg/g), the nanocomposite exhibited the higher adsorption capacity (31.95 mg/g). The adsorption behaviors of CS/MMT nanocomposite showed that the adsorption kinetics was in accorded with pseudo-second-order equation and the adsorption isotherms followed the Langmuir and Freundlich equation.
Authors: Dai Mei Chen, Jian Chen, Xu Ming Wang, Xin Long Luan, Hai Peng Ji, Feng Xu
Abstract: Sodium stearate modified montmorillonite(SSTA-MMT) is prepared by using the anion surfactant sodium stearate, and its structure is characterized by X-ray and FI-IR diffraction. The results show that sodium stearate can be intercalated into the interlayers of montmorillonite and the layer spacing is expanded from 12.74 to 48.05 Å with the loading concentration of sodium stearate increasing from 5 % to 100 % CEC of Na-MMT. The adsorption of methylene blue onto SSTA-MMT experiments show that the adsorption kinetic of methylene blue onto SSTA-MMT can be best described by the pseudo-second-order model and that the adsorption isotherm of methylene blue is in good agreement with the Langmuir equation.
Authors: Xiao Long Hu, Ying Ping Huang, Ai Qing Zhang, Xiao Rong Zhao
Abstract: Ferric oxide modified montmorillonite (Fe2O3@M) was prepared with the method of microwave-assisted ion-exchange and in-situ precipitation, with Fe2O3 nanoparticles intercalated into the interlayer of montmorillonite. Rhodamine B (RhB) was employed as a probe compound to study the adsorption characteristics of organic pollutants with Fe2O3@M as the adsorbent. The effect of pH and adsorbent dosage were investigated and the results showed that the maximum of adsorption capacity for RhB was 58.8 mg g-1. The adsorption capacity of Fe2O3@M for RhB was augmented along with the increase of adsorbent dosage. The Fe2O3 modified montmorillonite exhibits a much better adsorption capacity in an acidic solution than that in an alkaline solution. The adsorption process was well fitted the Langmuir and Freundlich isotherm model, respectively, and the adsorption reaction kinetics complied with a pseudo second-order kinetics model.
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