the silica boron sulfuric acid nanoparticles (sbsans) as an efficient heterogeneous solid acid catalyst with both brønsted and lewis acidic sites catalyzed the preparation of bis-4-hydroxycoumarin derivatives using reaction of aldehydes and 4-hydroxycoumarin under mild and solvent-free condition at room temperature. this new and efficient methodology has advantages in comparison with currently ...

A thin-layer chromatograpy (TLC) method is developed to analyze artemisinin (AT) and its derivatives, artemether (AM) and arteether (AE), using a silica-gel plate with a mobile phase containing pure chloroform. After development, all products are visualized after dipping in a 4-methoxybenzaldehyde dipping reagent of 1% (v/v) in an acidic solution of sulphuric acid (98%, v/v) and acetic acid (96...

para-aminobenzoic acid is supported on silica gel via reaction of activated silica gel and p-aminobenzoic acid which is then converted to its manganese and cobalt salts. a mixture of the manganese and cobalt salts of the acid is used to catalyze allylic and benzylic alcohols to their corresponding carbonyl compounds in reasonable yields using oxygen or air. reactions are clean and the catalysts...

In the process of smelting copper mineral a large amount of sulphuric dioxide (SO2) is produced. This compound would be highly pollutant if it was emitted to the atmosphere. By means of an acid plant it is possible to transform it into sulphuric acid, using for this a set of chemical and physical processes. In this way we dispose of a marketable product and, at the same time, the environment is...

The current knowledge in primary and secondary marine aerosol formation is reviewed. For primary marine aerosol source functions, recent source functions have demonstrated a significant flux of submicrometre particles down to radii of 20 nm. Moreover, the source functions derived from different techniques up to 10 microm have come within a factor of two of each other. For secondary marine aeros...

extensive application of silica nanoparticles (snps) in various industrial products has led to the development of silica extraction methodologies out of various waste products. rice husk is an agricultural waste with a high content of amorphous silica. however, the presence of metal ion impurities and unburned carbon in the rice husk content may present an adverse effect on product color and pu...

Atmospheric nucleation rates have been shown to be dependent on sulphuric acid (H2SO4) concentration (Weber et al. 1996, Sihto et al., 2006; Riipinen et al., 2007; Kuang et al., 2009). However, laboratory experiments on H2SO4-nucleation have failed to reproduce ambient observations (e.g. Wyslouzil et al., 1991; Viisanen et al, 1997; Ball et al, 1999; Young et al 2008). Very recently Sipilä et a...