Elementary Iodine-Doped Activated Carbon as an Oxidizing Agent for the Treatment of Arsenic-Enriched Drinking Water

An activated carbon impregnated with elementary iodine (I2), named IodAC, characterized by oxidation capability, was developed and applied to oxidize arsenite, As(III), to arsenate, As(V), in arsenic-rich waters. Batch and column experiments were conducted to test the oxidation ability of the material. Comparisons with the oxidizing agents usually used in arsenic treatment systems were also conducted. In addition, the material has been tested coupled with an iron-based arsenic sorbent, in order to verify its suitability for the dearsenication of drinking waters. IodAC exhibited a high and lasting oxidation potential, since the column tests executed on water spiked with 50 mg/L of arsenic (100% arsenite) showed that 1 cc of IodAC (30 wt% I2) can oxidize about 25 mg of As(III) (0.33 mmol) before showing a dwindling in the oxidation ability. Moreover, an improvement of the arsenic sorption capability of the tested sorbent was also proved. The results confirmed that IodAC is suitable for implementation in water dearsenication plants, in place of the commonly used oxidizing agents, such as sodium hypochlorite or potassium permanganate, and in association with arsenic sorbents. In addition, the well-known antibacterial ability of iodine makes IodAC particularly suitable in areas (such developing countries) where the sanitation of water is a critical topic.

Fission products and the dairy cow III. Transfer of 131iodine to milk following single and daily dosing

1. The transfer of 131I to milk has been studied in dairy cows following oral administration of carrierfree material in single doses as sodium iodide or as elementary iodine and in daily doses as sodium iodide.2. The total recovery from milk during the 6 days following administration of a single dose in twentyeight experiments on fifteen animals ranged from 1·3 to 19·4% of the dose with a mean value of 5·5%. The variations in recovery can be attributed largely to differences in the milk yield.3. There was no significant difference in the biological availability of 131I administered as iodide or iodine.4. The change in concentration of 131I in milk with time following daily dosing did not follow the predicted course, a peak value being observed in most animals after 1–3 days, followed by a fall and a subsequent rise to a steady value lower than was expected.5. The presence of a concentrating mechanism in the udder has been demonstrated by administration of sodium thiocyanate. Comparison of the milk total 131I: plasma dialysable 131I ratio at different times of the year indicates that the concentrating ability may be lower in the summer than in the autumn-spring months.