Application of advanced oxidation process for wastewater treatment has gained more attention recently. In this study, the efficiency of coagulation-flocculation pretreatment coupled with sulfate radical-based advanced oxidation process (SR-AOP) in the removal and mineralization of organic matter of sugarcane vinasse was evaluated. For coagulation-flocculation, jar-test experiment was carried out with ferric chloride as coagulant and the removal of TOC, color and UV 254 was determined. The results revealed that by using 15 g/L of coagulant, 70 % of TOC removal and nearly 100 % of UV 254 and color removal were achieved. The pretreated vinasse was then subjected to SR-AOP. In this study, sulfate radical was generated using persulfate (PS) and peroxymonosulfate (PMS) activated by Fe(II). The effect of reaction time, oxidants to Fe(II) ratio and pH on the TOC removal efficiency were investigated. For the effect of reaction time, the TOC removal was found to increase significantly for the first 5 min. TOC removal was found to increase with increasing concentration of Fe(II) for PMS. However, for Fe(II)/PS, the TOC removal efficiency was decreased with increasing Fe(II) concentration. Both Fe(II)/ PMS and Fe(II)/PS showed the highest TOC removal efficiency when the oxidation was carried out at pH 7. By using the selected optimum condition, nearly 70 and 49 % of TOC removal were achieved for PMS/Fe(II) and PS/Fe(II), respectively. Therefore, it can be concluded that SR-AOP can be a promising alternative method for TOC removal from sugarcane vinasse.

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This investigation represents a comparative study of four graphical methods for overall stability constant estimation techniques, included point wise calculation method, half integral method, linear plot method and least squares method, in purpose to select the most sensitive and accurate method, the paper aiming also to determine the parameters that affect the precision of these methods under investigation. Metal-ligand stability constant and stoichiometries of above systems are to be determined by Calvin and Bjerrum pHmetric titration technique as adopted by Irving and Rossotti. For this purpose titanium has been chosen as a central metal ion. Titanium element from first transition series of d-block and has four valence bond electrons 3d24s2. Acetic acid, oxalic acid and oxalacetic acid have been selected as ligands. The obtained results seem in a good agreement with each other, with some restriction on least squares method for accumulation of error in Kn-1. These suggestions have been introduced in conclusion for treatment of data by least squares method and Henderson's Hasselbalch's equation and other modifications have been done.

Four comparative methods for determination of stoichiometries and stability constants of chromium and zirconium complexes with citric and propanoic acids were studies, in purpose to select the most accurate and sensitive method, and to compare the formation of complexes of these two transition metals. (Cr 1st transition series group 6B, Zr 2nd transition series group 4B)Metal-ligand stability constants and stoichiometries of the above systems were determined by Calvin & Bjerrum pH-metric titration technique as adopted by Irving & Rossotti.Four methods employed were point-wise calculation method, half integral method, linear plot method and least squares method. The result seems in a good agreement with each other and any method can represents the other.