Brazilin was determined with hplc and the results

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Unformatted text preview: Sciences, Gadjah Mada University, Sekip Utara P.O. Box 21 Bulaksumur, Yogyakarta 55281, Indonesia E-mail: [email protected] In this research, dissolution of oxalic acid from spinach and determination of the concentration of the dissolved oxalic acid, and its use for Hg(II) ions photoreduction have been carried out. In the dissolution by water as a solvent, the time and temperature were optimized. The concentration determination was performed by permanganometric method. The photoreduction of Hg(II) ions was done in a closed reactor by means batch system equipped with UV lamp. In this step, oxalic acid concentration and reaction time on the effectiveness of Hg(II) photoreduction were also evaluated. The concentration of unreduced Hg(II) was determined by using Cold Vapor -Atomic Absorption Spectrometry (CV-AAS). The results of the research show that the oxalic acid dissoluti on from spinach is influenced by time and temperature dissolution process. The highest dissolution is obtained at 60 °C for 90 min. The content of oxalic acid in leaves (9.01 %) is found larger than that of in the stem (5.87 %). From the photoreduction study it is observed that the addition of oxalic acid with the increase of the concentration -both from spinach leaves and stem- can improve the Hg(II) photoreduction due to its ability in preventing electron and OH radicals recombination as well as in Hg(II) reduction. Furthermore, the highest photoreduction is reached in 300 min of the reaction time. 73 23rd-25th June 2010 3rd ICYC 2010 Universiti Sains Malaysia ANA-O21 PREPARATION AND CHARACTERIZATION OF SILICA MODIFIED WITH P -TERT-BUTYL-CALIX[4]ARENE, CALIX[4]ARENE AND CALIX[4]ARENE SULFONATE Alahmadi Sana Mohammad, Sharifah Mohamad and Mohd Jamil Maah Department of Chemistry, Faculty of Science, University of Malaya, Malaysia E-mail: [email protected] Three new silica gel modified with calix[4]arene derivatives have been prepared via modification of activated silica gel with toluene 2,4-di-iso-cyanate (TDI) as linker and p-tert-butyl-calix[4]arene, calix[4]arene and calix[4]arene sulfonate. The modified silica’s were characterized by Fourier Transform Infrared spectroscopy (FTIR), thermal analysis (TGA) and elemental analysis. FTIR s...
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