We demonstrate a sonication procedure for the removal of structure-directing micellar templates from mesoporous MCM-41. The method uses a 28 KHz ultrasound in an alcoholic solvent for disrupting micellar aggregation of the surfactant molecules, cetyltrimethylammonium bromide, which have filled the pores of the as-synthesized MCM-41. The majority (93%) of the surfactant molecules are removed out from the powder MCM-41 within a 15 min one-step sonication at a moderate temperature of 40°C. The structural and textural characterization techniques reveal that the resulted surfactant-free MCM-41 exhibits higher features compared to that of those obtained using the conventional calcinations approaches. The surfactant molecules are released into alcohol and can be recovered for reuse. This study provides an easy, cost-effective, mild and useful method for template removal from mesoporous materials at conventional conditions.

No abstract

No abstract

No abstract

No abstract

No abstract

Anatase nanocrystals were successfully synthesized and deposited onto polyacrylonitrile fibers with photocatalytic self-cleaning activity using the sol-gel process at low temperature. The original and treated samples have been characterized by several techniques such as scanning electron microscopy, fourier transform infrared spectroscopy, x-ray diffraction, diffuse reflectance spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The TiO 2 nanoparticles, have been found to form a homogeneous thin film on the fiber surface. The photocatalytic activity, tested by measuring the degradation of adsorbed Eosin Yellowish dye. The photoactivity of the titanium dioxide coated fibres is much higher than that observed in case of untreated fibers. The photocatalytic selfcleaning properties of the treated fibers was fully maintained performing several cycles of photodegradation. This preparation technique can be also applied to new fabrics to create self-cleaning properties in them. The thermogravimetric study of PAN/TiO 2 composite showed a slight increase of weight loss in the second step, which implied that, the dehydrogenation and oxygen uptake reactions would be promoted by the TiO 2 to some extent.Keywords: Polyacrylonitrile; Titanium dioxide; Thermogravimetric analysis; Differential scanning calorimetry; Photodegradation; Eosin Yellowish e-mail: Shalkeh737@gmail.com INTRODUTIONPolyacrylonitrile (PAN) is one of the most widely used precursor polymers for making high performance carbon fibers [1][2][3][4][5]. Study of the degradation of polyacrylonitrile has been a subject of interest for decades owing to its commercial value for the production of carbon fibers [6][7][8][9][10]. Spectroscopy, including infrared, ultraviolet, solid-state nuclear magnetic resonance (NMR) and x-ray photoelectron spectroscopy (XPS), and thermal analysis, including differential scanning calorimetry (DSC), differential thermal analysis (DTA) and thermogravimetric analysis (TGA), are the common tools in the study of polyacrylonitrile degradation [11][12][13][14].Semiconductor photocatalysis has been gathering much attention recently due to its promising application in chemical conversion and storage of solar energy for solar cells, hydrogen production, refractory pollutants elimination and self-cleaning surface [15][16][17][18].Among various oxide semiconductor photocatalysts, titanium oxide (TiO 2 ) has been proven so far to be the most promising material used for both fundamental research and practical applications. Because of its highly efficient photoreactivity, biological and chemical inertness, cost effectiveness, non-toxicity, and long-term stability against photocorrosion and chemical corrosion, titanium dioxide has been frequently employed in the environmental treatment and purification purposes [18][19][20][21][22]. Anatase TiO 2 has been identified as the most effective and useful photocatalyst under near UV illumination [23].The pairs of free electrons and holes are formed in the conduction and va...

No abstract