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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.

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.