Scientific Research Publishing

Read  full  paper  at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=52968#.VK3xYMnQrzE Author(s)   Jude O. Ighere , Karina Honjoya , Ramesh C. Chawla Affiliation(s) Chemical Engineering Department, Howard University, Washington DC, USA . ABSTRACT This paper discusses the toxicity and mobility of chromium species. And it presents the extent and kinetics of reductive remediation of hexavalent chromium, Cr + using ferrous ion, Fe 2+ . Molar ratios of 1:3 and 1:6 of Cr (VI) to Fe (II) were used. Integral method of data analysis showed reaction followed second-order kinetics with R square values near unity. Reaction was initially fast but with a rapid precipitation attributed to Cr (III)-Fe (III) in previous studies. This colloidal precipitate ultimately stops the reaction, which explains while conversion efficiency increases with increased molar ratio of Cr (VI) to Fe (II). The impact of pH was investigated by adjusting the C...

Read full paper at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=52659#.VKCoXcCAM4 Author(s)   Jun-Ichi Yamaguchi * , Emiko Shibuta , Yoshie Oishi Affiliation(s) Department of Applied Chemistry, Kanagawa Institute of Technology, Atsugi, Japan . ABSTRACT The reduction of various hydantoins with sodium borohydride gave the corresponding 4-hydroxy- 2-imidazolidinones in high yields. In contrast, reduction employing a boron trifluoride etherate-sodium borohydride system generated 2-imidazolidinones. In both reductions, the reactivity of the hydantoin was dependent on its substituents. The Lewis acid-promoted reactions of a 4-hydroxy-2-imidazolidinone with nucleophiles were also investigated. ...