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Magnetite (Fe3O4) and goethite (α-FeOOH) were synthesized via a hydrothermal approach and utilized as adsorbents for Cr6+ removal in an aqueous medium. Cr3+ could migrate into bulk Fe3O4 and stabilize in form of a solid solution.

A tridentate 3-pyridyl-based ligand containing a hexaazaphenalene skeleton (3-TPHAP-) with topologically isolated p orbitals was prepared by a one-pot reaction. It was successfully reacted with a Co2+ salt and a 1,4-benzenedicarboxylic acid co-ligand to give a porous coordination network. In the structure, the hexaazaphenalene skeleton interacts with water to form an internal hydrogen bonding network, allowing the entire pore space to be revealed by single-crystal X-ray diffraction (SXRD). The network structure consists of dimeric Co clusters featuring labile sites occupied by solvent molecules. Several guest molecules, namely, anthracene, triphenylene, and iodine, were incorporated inside the network. The resultant encapsulated structures were elucidated by SXRD, revealing unusual host-guest interactions with a subtle structural modulation.

EnvironmentAsia, 15, Special, 87-92

High purity silica is obtained after leaching glassy blade and trunk of cogon grass in HCl acid with various concentrations (1.5, 2.0, 2.5 and 3.0 M) and calcination at 500 °C for 4 h. The silica yield from the blade from all acid-leached samples is around 9 wt%, higher than that from the trunk (around 4 wt%). The sample leached with 2 M HCl has the highest silica purity (99.34 ± 0.02 wt%) and is further used in the syntheses of zeolite NaY by conventional and microwave-assisted hydrothermal methods (CH and MH). The NaY-CH has a larger particle size, BET surface area and total acidity than that NaY-MH. Interestingly, the NaY-MH has a larger external surface area and stronger acid strength.

This work reports syntheses of siliceous mesoporous MCM-41 by microwave-assisted hydrothermal process with CTAB:SiO2 ratio from 0.025 to 0.400 and NaOH:SiO2 ratio of 1.0, 1.3 and 2.0. From XRD results, the MCM-41 phase increases with CTAB:SiO2 ratio until 0.300. Another amorphous phase is produced from the gel with CTAB:SiO2 ratio of 0.400. MCM-41 from the optimal CTAB:SiO2 ratio (0.300) has surface area of 1138 m2 g−1 and pore wall thickness of 12.70 A. With CTAB:SiO2 ratio fixed at 0.300, the optimal NaOH:SiO2 ratio is 1.0. Then, an influence of microwave-assisted hydrothermal time is studied from 0 to 180 min on the gels with CTAB:SiO2 ratio of 0.300 and NaOH:SiO2 ratio of 1.0. All MCM-41 samples have essentially similar XRD pattern, surface area and pore-wall thickness. However, their TEM images indicate that the longer hydrothermal time produced MCM-41 with the less defects.

NaY was synthesized from fumed silica and further modified to form a composite with SBA-15. Textural properties and basicity of the composite NaY-SBA-15 were between those of the parent materials. Paraquat adsorption on NaY was 204.1 mg/g, higher than that on NaY synthesized with rice husk silica from the previous work. SBA-15 was a poor adsorbent for paraquat. Based on the weight of NaY, the adsorption capacity of analytical-grade paraquat on the NaY-SBA-15 composite was 241.5 mg/g-NaY. Moreover, the composite adsorbed blue dye from a commercial grade paraquat. Interaction between the NaY-SBA-15 and paraquat could be from C and N atoms in paraquat with oxygen atom on NaY-SBA-15.

Palm oil is largely produced in Thailand and sufficient to utilize as a biofuel feedstock through hydrodeoxygenation (HDO). In this work a new bifunctional catalyst consisting of nickel phosphide supported on zeolite mordenite in sodium form (Ni-P/NaMOR) was prepared by sequential impregnation and characterized extensively by several techniques to understand the reduction behavior, phases and distribution of nickel phosphides on the support. Nickel and phosphate precursors were transformed to Ni2P2O7 species by calcination and to a mixed phase between Ni12P5 and Ni2P by reduction. The phosphide species distributed in the zeolite cavities and external surface. The HDO of palm oil was tested in a down-flow stainless steel trickle bed reactor and the atmosphere was hydrogen. The mixed phase of nickel phosphides enhanced the HDO reaction. When tested by various temperatures and pressures, the optimum condition in this work was at 425 °C and 50 bar in which a complete of palm oil conversion, the largest HDO yield and selectivity toward C15-C18 alkanes were obtained. The green diesel and HDO yields from reduced Ni-P/NaMOR were larger than those from pure Ni2P and mixed Ni2P-Ni12P5. Interestingly, a small amount of isoparaffins was also observed likely due to the contribution of NaMOR support.

A multistate redox-active coordination network was prepared by stepwise synthesis via mechanochemical reaction to overcome the low solubility of ligands. Solid-state grinding between sparingly solu...

Control of the π–π interaction direction in a redox-active π-molecule based film led to the formation of new mechanistic nonvolatile resistive switching memory: a redox-active organic molecule, 2,5,8-tri(4-pyridyl)1,3-diazaphenalene, showed non-volatile bistable resistance states with a high on-off ratio, retention, and endurance only when the molecular orientation was anisotropic. Control experiments using redox-active/redox-inert organic molecules with isotropic/anisotropic molecular orientations implied that the formation of conductive oxidized π–π stacking layers from non-conductive neutral π–π stacking layers is responsible for resistive switching phenomena, indicating new mechanisms such as ReRAM. Our findings will give a comprehensive understanding of electron transport in organic solid materials based on the effects of redox-activity and molecular arrangement, leading to fabrication of a new class of ReRAM based on organic molecules.

Iron catalysts on zeolite beta from incipient wetness impregnation, Fe/HBEA with Fe loading 0.5–2.0 wt% were prepared and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS), and temperature-programmed desorption of ammonia (NH3-TPD). Fe in all catalysts was in the form of Fe2O3 and the acidity decreased with an increase of Fe content. From catalytic testing in phenol hydroxylation, the catalysts with lower Fe loading gave higher yields of catechol and hydroquinone and a lower amount of by-products than the catalyst with Fe loading 6.0 wt% in the previous work. The spent catalysts were analyzed by temperature-programmed oxidation using thermogravimetric analysis/mass spectrometry detector (TGA-MS). An amount of carbon deposit from all catalysts was in the range 10–15 wt%. However, carbon on the catalysts with lower Fe loading was removed at higher temperature.

Cetyltrimethylammonium (CTA + ) bromide is a template in the synthesis of MCM-41 which is normally removed by calcination. This work focuses on removal of CTA + by ion-exchange extraction from a siliceous MCM-41 synthesized by microwave-assisted hydrothermal method. The extraction was first conducted with aqueous and methanolic solution of NH 4 Cl under sonication. Methanol was a better solvent and further used with salts of various cation and anion. The extraction in the presence of ammonium salts was better than sodium and potassium salts due to the less change of the MCM-41 structure. In contrast, the type of anion in the ammonium salts had no effect on the removal efficiency. The methanolic solution containing NH 4 Cl was further studied from 15 min to 120 min and from 30 °C to 60 °C. The longer time and higher temperature improved the template removal but the extraction for 15 min at 60 °C was sufficient in terms of energy consumption.

Zeolite P in sodium form (NaP) is useful in the separation of small gases. However, the synthesis of NaP is slow due to a long crystallization time. Here, we report the fast synthesis of NaP by crystallization of the gel of NaY under microwave irradiation without any template. The influence of crystallization time and temperature on the zeolite morphology, the character of water desorption and functional vibration are confirmed by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. The suitable condition producing pure NaP crystalline is at 150 °C for 1 h. This is the shortest crystallization time to produce pure phase NaP.

The aim of this work is to determine paraquat adsorption capacity of zeolite NaX and Al-MCM-41. All adsorbents were synthesized by hydrothermal method using rice husk silica. For Al-MCM-41, aluminum (Al) was added to the synthesis gel of MCM-41 with Al content of 10, 15, 20 and 25 wt%. The faujasite framework type of NaX and mesoporous characteristic of Al-MCM-41 were confirmed by X-ray diffraction. Surface area of all adsorbents determined by N 2 adsorption–desorption analysis was higher than 650 m 2 /g. Al content and geometry were determined by X-ray fluorescence and 27 Al nuclear magnetic resonance, respectively. Morphology of Al-MCM-41 were studied by transmission electron microscopy; macropores and defects were observed. The paraquat adsorption experiments were conducted using a concentration range of 80–720 mg/L for NaX and 80–560 mg/L for Al-MCM-41. The paraquat adsorption isotherms from all adsorbents fit well with the Langmuir model. The adsorption capacity of NaX was 120 mg/g-adsorbent. Regarding Al-MCM-41, the 10% Al-MCM-41 exhibited the lowest capacity of 52 mg/g-adsorbent while the other samples had adsorption capacity of 66 mg/g-adsorbent.