Poly(vinylalcohol)-Tetraethoxysilane based NaA Zeolite Composite Membrane by Primary Growth Technique: Gas Permeation and Water-Ethanol Pervaporation Study

Poly(vinylalcohol)-tetraethoxysilane based NaA zeolite composite membranes were prepared onto the inner side of porous alumina support tube via primary crystallization processes at 100 degrees C for 4 h. Crystallization behaviour of the prepared NaA zeolite membranes was confirmed by XRD and FTIR studies. FESEM analysis revealed dense microstructure of the membrane with thickness of 15-20. m. Single gas permeation of He, N-2 and CO2 was measured with NaA zeolite membrane. Maximum permselectivity values of He/N-2 and He/CO2 were found to be 43.55 and 46.27, respectively. Pervaporation behaviour for the separation of ethanol/water mixture was studied with the membrane. Starting with 90% ethanol, 95.2% ethanol concentration was achieved within 600 min of pervaporation experiment

Low temperature synthesis of NaA zeolite membranes: The effect of primary and secondary crystallizations

NaA zeolite membranes were prepared on porous alpha-alumina support tubes (inner side) by primary (in-situ) and secondary (ex-situ) crystallization processes at 65 degrees C for 6 h, 12 h and 24 h each. For secondary crystallization process, poly(ethyleneimine) (PEI) was used as a buffer layer for proper attachment of the NaA seed crystals (prepared at 65 degrees C/2 h) onto the alumina support surface. The membranes prepared by primary crystallization process showed thicknesses of about 10 mu m, 20 mu m and 30 mu m for growth times of 6 h, 12 h and 24 h, respectively, while the membranes prepared by secondary crystallization process rendered the corresponding thicknesses of 25 mu m, 35 mu m and 70 mu m, respectively. PEI coating rendered good quality of membrane for secondary crystallization process with lower growth time (6 h). The better quality of membrane which had interlocked dense structure with minimum defects was obtained for primary crystallization at 65 degrees C for 12 h growth time. Pervaporation study for ethanol/water mixture was performed with the prepared membranes. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Bi-template assisted synthesis of mesoporous manganese oxide nanostructures: Tuning properties for efficient CO oxidation

A simple soft bi-templating process was used for the synthesis of mesoporous manganese oxide nanostructures using KMnO4 as a precursor and polyethylene glycol and cetyltrimethylammonium bromide as templates in the presence of benzaldehyde as an organic additive in alkaline media, followed by calcination at 400 degrees C. X-ray diffraction and Raman spectroscopic analysis of the calcined products confirmed the existence of stoichiometric (MnO2 and Mn5O8) and non-stoichiometric mixed phases (MnO2 + Mn5O8) of Mn oxides obtained by tuning the concentration of the additive and the synthesis time. The surface properties of the prepared Mn oxides were determined by X-ray photoelectron spectroscopy. The mesoporosity of the samples was confirmed by N-2 adsorption-desorption. Different synthetic conditions resulted in the formation of different morphologies of the Mn oxides (alpha-MnO2, Mn5O8, and alpha-MnO2 + Mn5O8), such as nanoparticles, nanorods, and nanowires. The synthesized mesoporous Mn oxide nanostructures were used for the catalytic oxidation of the harmful air pollutant carbon monoxide. The Mn5O8 nanoparticles with the highest Brunauer-Emmett-Teller surface area and the non-stoichiometric manganese oxide (alpha-MnO2 + Mn5O8) nanorods with a higher Mn3+ concentration had the best catalytic efficiency

Role of silane grafting in the development of a superhydrophobic clay-alumina composite membrane for separation of water in oil emulsion

Hydrophobic composite kaolin-coated clay-alumina membranes are unique choices for water in oil emulsion separation. In this work, a membrane fabrication approach is presented using kaolin clay coating in the clay -alumina tubular composite support tube and subsequently grafting by different concentrations of fluoroalkyl silane (FAS: 1H, 1H, 2H, 2H, -Perfluorooctyltriethoxysilane) on the membrane surface. Different concentrations of fluoroalkyl silane formed distinctive hierarchical structures which exhibited hydrophobicity of the membrane surface. The pore property, surface roughness properties, and thermogravimetric properties can be suitably tailored by tuning the silane concentration in the grafting solution. The surfaces of comparatively higher silane content grafted (M50 and M100) composite membranes were found to be superhydrophobic. Comparably, our optimal composite membrane (M100) displayed a moderate steady flux rate of 80-100LMH (Lm-2h-1) and excellent water rejection (> 99%) properties during the separation of water in hexane and toluene emulsion at a cross-flow transmembrane pressure of 1 bar. The role of silane concentration on permeated hexane and toluene flux rate, water rejection rate, surface wettability, microstructure, and hydrophobic stability reveals new dis-tinguishing insights into the hydrophobic clay-alumina composite membrane fabrication

A facile synthesis of mesoporous NiO nanosheets and their application in CO oxidation

Mesoporous NiO nanosheets were prepared by a facile sol–gel process using Aerosol-OT, Bis(2-ethyl hexyl) sulfosuccinate sodium salt (AOT) as anionic surfactant. The products were analyzed by XRD, Raman spectroscopy, N2 adsorption–desorption, FESEM and TEM studies. The morphology and textural properties of the products were tuned by using different amounts of the surfactant. TEM images exhibited nanosheets particles of thickness 80–100 nm in which nanograins (10–20 nm) were assembled. A probable mechanism was illustrated for the formation of NiO nanosheets. Catalytic activity for CO oxidation was performed with the synthesized products. The nanosheet particles obtained in the presence of 1 mmol AOT with the surface area of 88.23 m2 g−1 exhibited the better CO oxidation, i.e., T50 (50% conversion) and T100 (100% conversion) were at 245 °C and 288 °C, respectively

Solvothermal-assisted evaporation-induced self-assembly process for significant improvement in the textural properties of γ-Al2O3, and study dye adsorption efficiency

A comparative study of the textural properties of γ-Al2O3 prepared by solvothermal-assisted evaporation-induced self-assembly (SA-EISA) and conventional evaporation-induced self-assembly (EISA) processes has been carried out using aluminum isopropoxide, triblock copolymer-type nonionic surfactant (Pluronic P123) and ethanol. The solvothermal reaction was carried out at 100 °C for 24 h followed by slow drying at 60 °C for 48 h. The synthesized products were characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) analysis, N2 adsorption–desorption study and transmission electron microscopy (TEM). The γ-Al2O3 prepared by SA-EISA process became stable up to 1000 °C. The powder prepared by SA-EISA process resulted in a significant increase in textural properties (BET surface area, pore volume and pore diameter) compared to that prepared by conventional EISA process. A better adsorption capacity for Congo red, a carcinogenic dye used in textile industry, was exhibited by the powders prepared by SA-EISA process. A proposed mechanism was illustrated for the formation of mesoporous γ-Al2O3 obtained by EISA and SA-EISA processes

Mesoporous CuO-TiO2 microspheres for efficient catalytic oxidation of CO and photodegradation of methylene blue

Mesoporous CuO-TiO2 microspheres were synthesized by a simple solution based process. The synthesized products were characterized by XRD, FTIR, Raman spectroscopy, N-2 adsorption -desorption study, FESEM, TEM, XPS and UV vis spectroscopy. The catalytic performances for oxidation of CO and photocatalytic degradation of methylene blue (MB) were studied with the synthesized microspheres. For higher concentration of CuO in the microspheres, the T-50 (50% conversion) and T-100 (100% conversion) of CO oxidations were found to be 139 degrees C and 168 degrees C, respectively. For lower concentration of CuO in the microspheres having BET surface area of 67.7 m(2) g(-1) showed the maximum (about 93%) photodegradation of MB

Synthesis of Lactose-Derived Nutraceuticals from Dairy Waste Whey-a Review

Due to stricter environmental legislation and implementation of the ``waste valorization'' concept, recycling of dairy effluent, whey, has drawn a considerable attention. The main constituent of whey is lactose, which is responsible for high biological oxygen demand (BOD) and chemical oxygen demand (COD) values. Therefore, without going to its direct disposal into aquatic system, synthesis of nutraceuticals from lactose is considered a commendable challenge. Lactose-derived nutraceuticals, such as galacto-oligosaccharide (GOS), lactulose, lactitol, lactosucrose, lactobionic acid, gluconic acid, lactone, and tagatose, have been synthesized through different chemical and biochemical reactions, such as hydrolysis, transgalactosylation, oxidation, reduction, isomerization, and hydrogenolysis, considering raw whey or isolated lactose as feedstock. Pure biocatalyst (enzyme) and inorganic catalyst have been used for the synthesis of lactose-based nutraceuticals by different types of operations, such as conventional batch and continuous bioreactors with free catalyst, continuous packed bed bioreactor with immobilized catalyst, moving bed reactor, and membrane-assigned bioreactor. Moreover, in many cases, lactose-based nutraceuticals (lactic acid, lactosucrose, lactobionic acid, gluconic acid, and tagatose) have been synthesized by microbial fermentation process. Free microbial cell in batch and continuous fermentor and whole cell immobilized packed bed bioreactor have been used for this purpose. This review presents and compares different process-related technological aspects for synthesis of lactose-derived nutraceuticals from whey