Effect of different impurities in potable water on iodine

Abstract

In this research an investigation has been carried out to observe the behavior of iodide salt In impure water at different conditions of water. Potable water has different impurities. 'Treated water more often contains free chlorine for use of excess bleaching powder or chlorine gas in water to safe guard against the disease producing microorganisms. Ground water contains iron due to geological formation of the aquifer. In some locations these impurities exceed allowable limits and may exist in water in high concentration. In this study different experiments have been conducted to observe the behavior of iodide salt in distilled water containing these two different impurities independently at different temperatures, with elapsed.time at various temperatures and pH conditions. The study reveals that if iodide salt is used in chlorinated water, free iodine will liberate. Due to volatile nature of iodine, the liberated free iodine will escape into air under exposure condition even at low temperature with elapsed time. The loss in free residual iodine increases with increase in temperature and with increased elapsed time at constant temperature under exposure to open air•. Acidic condition of water accelerates the evaporation rate of iodine. Iodine that is used in table salts as iodide form exists in water with a trace amount. If this trace quantity of iodine reacts with chlorine in water, the liberated free iodine will escape into air instantaneously. But when iodine is used as iodate form in table salts, no effect of chlorine is noticeable on iodine .. The reaction of ferric iron with iodide salt is very slow due to precipitate form of iron in water as ferric hydroxide. The instantaneous reaction depends on both ferric iron and iodide ion concentration in water. The experimental results show that no rapid reaction of ferric iron with iodide ion is observed even in water containing 10 ppm ferric iron. A rapid reaction occurs at 15 ppm iron concentration in water with 90 ppm iodine as iodide form. This states that there is no significant effect of iron on iodine if iodine is used as iodide form in table salts.. A field survey on iodine deficiency disorders and people's argument about iodized table salts has been carried out in different districts of Bangladesh. The survey shows that nowadays most of the people in Bangladesh, use iodized table salts to mitigate iodine deficiency in their bodies. In the' coastal zone of Bangladesh where sea foods are available and soil contains iodine, goitrous problem and other iodine deficiency disorders are insignificant. But in the northern zone of Bangladesh these problems are very severe. Because people in those areas are in crisis of sea foods and soil lacks iodine. Poor people specially women suffer much more than males from iodine deficiency disorders.