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Engineering crystal facets have been proved as one of the most promising strategies for promoting photocatalytic performance of titanium dioxide (TiO2). The earlier research in this field focused on trying to obtain as high ratio of the high energy {001} facet as possible, while later found that the co‐existence of facets is more beneficial. However, controlling crystals to expose suitable facet pairs and facet ratios remains challenging. In this work, we not only comprehensively match possible low‐index facets such as {101}‐{001} and {010}‐{001} facet pairs, but also systematically tune their ratios. Moreover, these faceted particles can be directly grown onto the transparent conductive substrate, which can be directly used as a photoanode. So, their intrinsic behaviors can be precisely evaluated without interference from other exogenous factors such as binders, additives, or assembly skills. Various characterization techniques reveal that both the types of facet pairs and the ratios of facets play crucial roles on photocatalytic behaviors, due to the different electron affinity and dissociative adsorption ability of water molecules on a particular facet. Charge transport and surface chemistry have been thoroughly investigated to identify the underlying mechanism. This work sheds light on a material design strategy considering a suitable match of facet pairs for optimizing photocatalytic performance for a wide variety of applications. [ABSTRACT FROM AUTHOR]

Abstract: Silica with 98% purity was prepared from rice husk by acid leaching and used as a silica source for the syntheses of zeolite beta (Beta) under hydrothermal conditions with gel Si/Al ratios of 8, 13, 15, 20, 50, 100, 150, and 200. Based on powder X-ray diffraction patterns, samples with gel Si/Al ratios of 8–20 contained only the pure phase of Beta and the highest relative crystallinity was observed in the Beta with gel Si/Al ratio of 13. This sample was further characterized by scanning electron microscopy, particle size analyzer and N2 adsorption analysis. The Beta particles were sphere shaped with the average particle size of 1.5μm and a surface area of 670m2 g−1. The samples with gel Si/Al ratios ranging from 50 to 200 showed mixed phases of Beta and ZSM-12, and the latter phase was more dominant as the Si/Al ratio increased. [Copyright &y& Elsevier]

Zeolite NaY synthesized from a typical procedure could suffer from agglomeration. Adding non-refluxed cogon grass (NG) to the synthesis gel could produce NaY with good dispersion and uniform crystal size. Small molecules produced from cogon grass in alkaline conditions could prevent agglomeration. The obtained zeolite (Y-NG) has a crystallinity and surface area comparable to the synthesis without grass (Y-WG). Y-NG demonstrated similar paraquat adsorption capacity to Y-WG at high initial concentrations. On the other hand, the zeolite from the addition of acid-refluxed grass (Y-RG) has the lowest crystallinity, smallest surface area, and poorest paraquat adsorption capacity. The effect of grass amount on the zeolite structure was studied. One gram of cogon grass was the optimum amount to add to the synthesis gel. [ABSTRACT FROM AUTHOR]

Zeolites in powder form have the potential to agglomerate, lowering access to active sites. Furthermore, a suspension of fine zeolite powder in liquid media is difficult to separate. Such drawbacks could be improved by dispersing zeolite crystals on support materials. This work demonstrates the dispersion of zeolite NaY crystals on bamboo wood by mixing the wood with zeolite gel before hydrothermal treatment. The syntheses were performed with acid-refluxed and non–refluxed wood. The phase of zeolites, particle distribution and morphology, zeolite content in the wood, and zeolite–wood interaction were investigated using X-ray diffraction, X-ray tomography, scanning electron microscopy, thermogravimetric analysis, nitrogen sorption analysis, and X-ray photoelectron spectroscopy. Higher zeolite content and better particle dispersion were obtained in the synthesis with the acid–refluxed wood. The composite of NaY on the acid-refluxed wood was demonstrated to be an effective adsorbent for Ni(II) ions in aqueous solutions, providing a higher adsorbed amount of Ni(II) per weight of NaY. [ABSTRACT FROM AUTHOR]

The heterogeneous base catalysts were developed from zeolite-geopolymer hybrid material (Zeo-Geo) as a new support for potassium in transesterification of soybean oil. Zeo-Geo was prepared by mixing Al metal, metakaolin, and fumed silica in NaOH solution and curing at 60 °C, 24 h and 110 °C, 12 h. The Zeo-Geo contained a mixed phase of geopolymer and X-type zeolite. The xK/Zeo-Geo with x = 5, 10 or 15 wt% potassium were prepared by impregnation of Zeo-Geo with potassium acetate followed by calcination at 400 °C for 3 h. The phases of potassium were mainly K 2 O and K 2 CO 3 and the basicity increased with potassium loading. The 15K/Zeo-Geo was the most active catalyst in transesterification of soybean oil with methanol, at 70 °C providing 97.64% biodiesel yield under the optimum condition: reaction time = 3 h, methanol to oil molar ratio = 16:1 and catalyst amount = 2 wt%. The catalyst was reused in 5 cycles without a significant activity loss and leaching of active species. From this study, 15K/Zeo-Geo has a potential for further development in large-scale production. [ABSTRACT FROM AUTHOR]

An ethanol biosensor based on alcohol dehydrogenase (ADH) attached to Au seeds decorated on magnetic nanoparticles (Fe3O4@Au NPs) is presented. ADH was immobilized on Fe3O4@Au NPs, which were subsequently fixed by a magnet on a carbon paste electrode modified with 5% (m: m) MnO2. Optimum conditions for the amperometric determination of ethanol with the biosensor were as follows: working potential + 0.1 V (vs. Ag/AgCl); supporting electrolyte: 0.1 M phosphate buffer solution at pH 6.8 containing 0.25 mM of the coenzyme (NAD+); working electrode: carbon paste with magnetically attached Fe3O4@Au NPs (0.012 mg⋅cm-2 electrode area) with immobilized alcohol dehydrogenase (120 units per cm² of electrode area). Linearity between signal and concentration was found for the range from 0.1 to 2.0 M ethanol (r² = 0.995) with a detection limit of 0.07 M, a sensitivity of 0.02 µA⋅mM-1⋅cm-2, a reproducibility of 4.0% RSD, and a repeatability of 2.7% RSD. The results for the determination of ethanol in alcoholic beverages showed good agreement with gas chromatography (GC) with recovery of 96.0-108.8%. [ABSTRACT FROM AUTHOR]

Hierarchical fluoride-containing zeolite HY (Hie-HY(F)) is an interesting material because it tunes both a high mesoporosity and a moderate acid property, which could benefit the transformation of xylose to xylitol. Herein, we synthesized a new Hie-HY(F) by etching NH 4 Y with ammonium fluoride (NH 4 F) under ultrasonication at 60 °C for 20, 40, and 60 min. After etching with NH 4 F solution, the Hie-HY(F)s contained fluoride in the zeolite frameworks with high mesoporosity and moderate acid properties. The sonication time longer than 20 min caused the structure to collapse rather than the creation of mesoporosity. The Hie-HY(F)s were further used as supports for the Ru catalyst. When loaded with Ru precursor and calcined in air, RuO 2 phase was formed in all catalysts. The RuO 2 supported on Hie-HY(F)s had a lower reduction temperature than that on HY. Ru supported on Hie-HY(F)-20 gave the reactivity of xylose conversion to xylitol, the highest yield of 80.1 %, providing the reusability up to four cycles. [Display omitted] • Synthesis of hierarchical fluoride-containing zeolite Y (Hie-HY(F)s) was disclosed. • Hie-HY(F)s was done by etching in NH 4 F solution under sonication at various times. • Dealumination and fluorination played a crucial role in mesoporosity and acidity. • Hie-HY(F)s was used as a novel support for Ru in xylose conversion to xylitol. • Ru/Hie-HY(F)-20 gave the highest xylitol productivity, 80.1 % yield. [ABSTRACT FROM AUTHOR]

Abstract: Reducibility of 6wt.% cobalt impregnated on zeolite Y in sodium and proton form (6Co/NaY and 6Co/HY, respectively) was studied mainly by X-ray absorption spectroscopy including X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) along with other techniques such as X-ray diffraction. The results indicated that the physicochemical properties of Co strongly depended on the form of support. After calcination in air, Co2+ species were observed on both NaY and HY. After reduction in H2 at 420°C for 5h, the Co species in 6Co/NaY were partially reduced to metallic form and each Co was surrounded by other six Co atoms. On the other hand, Co species in 6Co/HY was not reducible under a similar condition and each Co was surrounded by four oxygen atoms. Because the metallic cobalt is the active form for butane hydrogenolysis, 6Co/NaY was more active than 6Co/HY at 400°C giving average conversion of 32% and 2%, respectively. [Copyright &y& Elsevier]

Wood of the Lead tree (Leucaena Leucocephala) is pyrolyzed in an Iwasaki kiln to produce charcoal with a graphitic-like structure with a surface area of 329 m2/g. The charcoal is ground into 3 different particle sizes (large, medium, and small) and activated with carbon dioxide to produce activated carbon. The structure, morphology, elemental composition, porosity, and functional groups of the activated carbon samples are compared with the charcoal precursor. The larger particle size of the charcoal gives activated carbon with a larger surface area, up to 609 m2/g. In addition, wood vinegar is collected during the pyrolysis at 3 temperature ranges and extracted by n-hexane, diethyl ether, and ethyl acetate. The compositions depend on the collecting temperature. The main components are ketones, organic acids, furan and pyran derivatives, esters, phenols and derivatives, alcohols, and alkanes. [ABSTRACT FROM AUTHOR]

The nature of paraquat adsorption is compared between zeolite NaX and NaY which have the same faujasite structure but different Si/Al ratio, namely 1.2 and 2.2, respectively. The adsorption was proposed to occur via ion exchange and expected to increase with Al content. However, NaX had a lower paraquat adsorption capacity than NaY. The bare and paraquat-containing zeolites (PQX and PQY) were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption–desorption analysis, magic-angle spinning nuclear magnetic resonance (MAS) NMR, and X-ray photoelectron spectroscopy. The presence of adsorbed paraquat was confirmed by Fourier transform infrared spectroscopy. Paraquat adsorbed in supercages of the zeolites resulting in a decrease of surface area and displacement of sodium cations. Results from 23Na MAS NMR and X-ray photoelectron spectroscopy indicated that interaction of sodium ions in the cavity of NaX was stronger than that in NaY, making it less exchangeable with paraquat. [ABSTRACT FROM AUTHOR]

Adsorption is one of the methods used to reduce free fatty acid in feedstock oils with high acid content that are used for the production of biodiesel. This work investigated MCM-41 synthesized from rice husk silica for the adsorption of oleic acid in isooctane. The adsorption conformed to the Langmuir isotherm model and equilibrium adsorption capacities at 25.0°C were 277.8 mg/g for as- synthesized MCM-41 and 270.3 mg/g for template- removed MCM-41. The determined free energy and enthalpy of adsorption showed that the adsorption was spontaneous and exothermic. Adsorption of oleic acid in soy bean oil was also demonstrated. Results showed that as-synthesized MCM-41 was a better adsorbent than template-removed MCM-41 for oleic acid removal from soybean oil. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Adsorption of paraquat and pirimiphos-methyl in water was performed on four adsorbents including montmorillonite (Mt), organoclay (TDA-Mt) from intercalation of Mt with tetradecylammonium chloride, and mesoporous Mt from intragallery templating method (with and without Ti addition). The adsorbents were characterized by X-ray diffraction, N2 adsorption-desorption, and transmission electron microscopy. Paraquat adsorption isotherms followed Langmuir model and the adsorption capacity was as follows: TDA-Mt>Mt>mesoporous Ti-Mt>mesoporous Mt. The adsorption mechanism on TDA-Mt and Mt might be via ion exchange. The adsorption on mesoporous samples was on the external surface with negative charge. The presence of Ti enhanced the adsorption capacity. Pirimiphos-methyl adsorbed on negative charge of the external surface of Mt samples. The adsorbed amount increased with the initial concentration due to a strong intermolecular interaction. [ABSTRACT FROM AUTHOR]

Zeolite NaX was synthesized by using rice husk silica and used as a catalyst support. It was impregnated with potassium acetate buffer solution to produce xK/NaX where x was potassium loading of 4, 8, 12 and 16 wt.%. After calcination the zeolite characteristic in all catalysts were still observed. The surface area and micropore volume decreased with potassium loading indicating that the cavities were occupied. The potassium precursor was mainly converted to carbonate which had strong basicity. As the basicity increased with the potassium loading, the bettter catalytic performance in transesterification of Jatropha seed oil to biodiesel was observed. The best catalyst was 16K/NaX which gave 95.2 ± 0.96% biodiesel yield. [ABSTRACT FROM AUTHOR]

The goal of this work was to characterize active species in potassium catalysts supported on zeolite NaY prepared by ultrasound-assisted impregnation with acetate buffer (K/NaY-U). A catalyst from conventional impregnation (K/NaY) was also prepared for comparison. The potassium precursor from acetate buffer solution decomposed at 370–480 °C and converted to potassium carbonate as realized by several techniques. Both K/NaY-U and K/NaY contained moderate and strong basic sites. The K/NaY-U had a better dispersion of potassium species. Compared to K/NaY in a catalytic transesterification of palm oil, the reaction over K/NaY-U was faster and the biodiesel yield 72% was obtained in 2 h. The longer reaction time increased the yield slightly but not preferred in terms of energy consumption. The amount of potassium before and after catalytic testing was similar. [ABSTRACT FROM AUTHOR]

Photocatalysts were prepared by using TiO2 at 10 and 30 wt% grafted on rice husk silica (RHS) and zeolite NaY. The photocatalysts were characterized by X-ray diffraction and N2 adsorption-desorption analysis. The TiO2 in the anatase phase was well dispersed on the external surface area of the supports. Paraquat adsorption on the catalysts (determined before the photocatalytic testing) mainly occurred on the supports. The adsorption on the TiO2/NaY was much higher than that on the TiO2/RHS. In photocatalytic testing, both the 10 and 30% TiO2/NaY catalysts were not active probably due to high adsorption of the paraquat on the supports. In contrast, both of the TiO2/RHS catalysts were active and the best photocatalyst was the 30% TiO2/RHS. The supported catalyst showed a higher activity than the bare TiO2 indicating the enhancement from the dispersion of the RHS. Moreover, the photocatalytic degradation of paraquat on the 30% TiO2/RHS was similar to commercial TiO2 (P25) with the same TiO2 content. [ABSTRACT FROM AUTHOR]

An alternative reduction route of Pd-promoted Co 3 O 4 supported on SBA-15 under ethanol dehydrogenation and decomposition (ED) was studied by an operando time-resolved X-ray absorption spectroscopy (TR-XAS) to understand the insight nature of materials. The catalysts, xPd-10Co/SBA-15, were prepared by co-impregnation method where the Pd content, x = 0.2, 0.5 or 1.0 wt% and Co content = 10.0 wt%. The precursors were transformed to PdO and Co 3 O 4 after calcination and to metallic form after reduction. The reducibility of Co 3 O 4 to metallic Co in 1Pd-10Co/SBA-15 was 98.0%, whereas the metallic form was not produced in the absence of Pd. This catalyst also provided the highest H 2 yield of 80% from ED at 500 °C. The ED-reduced 1Pd-10Co/SBA-15 was tested in reverse water gas shift reaction (RWGS) and characterized by the operando TR-XAS. The CO selectivity from CO 2 was 97.8%, slightly higher than conventional H 2 -reduced 1Pd-10Co/SBA-15. [Display omitted] • Reduction of Co 3 O 4 in ethanol dehydrogenation and decomposition (ED) was disclosed. • Effect of Pd loading on the reducibility of Co 3 O 4 to metallic Co in ED was studied. • Pd with 1.0 wt% provided the highest reducibility of Co 3 O 4 and H 2 yield under ED. • Pd-Co/SBA-15 reduced under ED was active in reverse water gas shift (RWGS). • Pd-Co/SBA-15 reduced under ED provided 97.8% CO selectivity from RWGS. [ABSTRACT FROM AUTHOR]

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 N2 adsorption-desorption analysis was higher than 650 m2/g. Al content and geometry were determined by X-ray fluorescence and 27Al 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. [ABSTRACT FROM AUTHOR]

The goal of this work was to utilize rice husk silica (RHS) and porous materials synthesized with RHS, including mesoporous material (MCM-41) and microporous materials (zeolite NaY and NaBEA), for adsorption of herbicide paraquat. The adsorption occurred although cation exchange and the capacity decreased in the following order: NaY>NaBEA> MCM-41>RHS, consistent with the amount of Al. The adsorption on all adsorbents fitted well with the Langmuir model and the maximum adsorption capacity of 185.2 mg/g-adsorbent was obtained on NaY. In addition, blue dye in commercial grade paraquat did not interfere with paraquat adsorption. Although MCM-41 was the most efficient adsorbent for the blue dye, RHS was favorable in terms of production cost. A mixture of NaY and RHS is recommended for simultaneous adsorption of paraquat and blue dye. [ABSTRACT FROM AUTHOR]

Abstract: A single-use optical chemical sensing film based on immobilized disodium-1-nitroso-2-naphthol-3,6-disulfonate or nitroso-R salt (NRS) in a modified chitosan film was developed for the determination of Co(II) in aqueous solution. In the presence of Co(II), the color of the sensing film changed from yellow-green to reddish orange as a result of complex formation between Co(II) and NRS. The absorbance measurement of the complex was made at 525nm because the background of the sensing membrane was minimal. An optimum response of the sensing film to Co(II) was obtained in a solution with a pH of 5. Two sample sizes were studied: 3mL with a Co(II) concentration range of 1–60ppm and 300mL with a Co(II) concentration range of 35–400ppb. Linear calibration curves were obtained from both sample sizes with limits of detection of 0.82ppm and 12ppb, respectively. The relative standard deviation for five separate films in 10ppm Co(II) solution was 1.7% and that for the other five individual films in 40ppm Co(II) solution was 0.41%. The sensing films exhibited good stability for 2 months and were applied for determination of Co(II) in water samples with satisfactory results. [Copyright &y& Elsevier]

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 Ni 2 P 2 O 7 species by calcination and to a mixed phase between Ni 12 P 5 and Ni 2 P 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 C 15 -C 18 alkanes were obtained. The green diesel and HDO yields from reduced Ni-P/NaMOR were larger than those from pure Ni 2 P and mixed Ni 2 P-Ni 12 P 5. Interestingly, a small amount of isoparaffins was also observed likely due to the contribution of NaMOR support. Unlabelled Image • Nickel phosphide on NaMOR was tested in hydrodeoxygenation (HDO) of palm oil. • The catalyst contained a mixed phase between Ni 12 P 5 and Ni 2 P with bifunctionality. • The mixed phosphide phase gave high yield and selectivity toward C 15 -C 18 alkanes. • The NaMOR support contributed a formation of isoparaffins. • The optimum condition to yield the largest HDO was at 425 °C and 50 bar. [ABSTRACT FROM AUTHOR]