Iron selenocyanates

A similar reaction yielding alkyl selenocyanates occurs between trialkylboranes and sodium selenoiso-cyanate in the presence of iron(ni) ions. There is a strong preference for the transfer of secondary or tertiary as compared to primary alkyl groups. This allows selective transfer reactions to be carried out in yields of 57-68% (equation 71) and 67-78% (equation 72). ... 

It has been shown that the predominate state of the selenium in these SSW streams is as the selenocyanate (SeChT) [1]. The selenocyanate in SSW is oxidized by refinery biotreaters to selenite (SeOs ), which can then be removed via an iron based treatment process. One of the most effective of these iron-based processes is iron co-precipitation process. However, the selenium can also occur as selenate (Se04 )> which is not removed during the iron coprecipitation process [2]. In order to design effective treatment protocols to remove the selenium, more than just the concentration of the metal must be determined. Without knowledge of the types of selenium species present in the water, design of an effective removal treatment protocol... 

Building upon a study that was performed for the Western States Petroleum Association (WSPA) [1] to optimize iron-based selenium removal processes, a scheme was developed to measure total selenium, and the individual selenium species present in the SSW and aqueous streams. Total selenium was measured by ICP-MS after a peroxide/acid digestion pretreatment of the samples. Speciation of the selenium was accomplished using an anionic ion chromatographic separation followed by quantification of the selenite, selenate, and selenocyanate using ICP-MS. 

Once the ability of the IC-ICP-MS system to repeatedly separate the three selenium species was confirmed, efforts focused on investigating process variables which would influence the concentration of various selenium species, specifically selenocyanate (SeCN) in the SSW. One such process variable studied was pH. The study of the pH effects on the conversion of the SeCN to other selenium species, such as selenate and selenite, was undertaken to define the pH boundaries fiir any pre-treatment or treatment conditions for the SSW. Knowledge of tbrs behavior would influence the design of any systems, e.g., iron co-precipitation, built to remedate the Se in the SSW streams. 

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