Iodine

About: Iodine is a research topic. Over the lifetime, 8936 publications have been published within this topic receiving 139981 citations. The topic is also known as: I & element 53.

Iodide-mediated photooxidation of arsenite under 254 nm irradiation.

Abstract: The preoxidation of As(III) to As(V) is a desirable process to increase the removal efficiency of arsenic in water treatment In this work, the photooxidation of As(III) under 254 nm irradiation was investigated in the concentration range of 1-1000 microM in the presence of potassium iodide (typically 100 microM). Although the direct photooxidation of As(III) in water was negligible, the presence of iodide dramatically enhanced the oxidation rate. The quantitative conversion of As(III) to As(V) was achieved. The quantum yields of As(III) photooxidation ranged from 0.08 to 0.6, depending on the concentration of iodide and As(III). The excitation of iodides under 254 nm irradiation led to the generation of iodine atoms and triiodides, which seem to be involved in the oxidation process of As(III). Because the efficiency of iodine atom generation is highly dependent on the presence of suitable electron acceptors,the photooxidation of As(III) was efficient in an air- or N2O-saturated solution but markedly reduced in the N2-saturated solution. The production of H2O2 was also accompanied by the generation of As(V). The addition of excess methanol (OH radical scavenger) did not reduce the photooxidation rate at all, which ruled out the possibility of hydroxyl radical involvement. It was found that the in situ photogenerated triiodides oxidize As(III) with regenerating iodides by completing a cycle. The proposed UV254/KI/As(III) process is essentially an iodide-mediated photocatalysis.

Biokinetics of Iodide in Man: Refinement of Current ICRP Dosimetry Models

Abstract: A compartmental model describing the distribution and retention of radioactive iodide in thyroid and other organs is presented. The model is developed from published ICRP models. It is designed primarily for radiation dosimetry of iodine radionuclides used in nuclear medicine, but may also be useful for occupational radiation protection. In the proposed model, the distribution of iodide to the thyroid is assumed to be more rapid than in earlier models. Uptakes in stomach wall and salivary glands are considered, and the absorbed doses to these organs calculated. The partitioning of iodide between stomach wall and content is also discussed. Recirculation of organic iodine is also taken into account. Age-dependent half-times for iodide in the thyroid, as well as for organically-bound iodine are presented. The proposed model is applicable for dose estimations with different uptakes in the thyroid as well as for the situation when the thyroid is blocked, completely or incompletely.

Distribution of iodide and iodate in the Atlantic sector of the southern ocean during austral summer

Abstract: The biogeochemistry of iodine in the waters of the Atlantic sector of the Southern Ocean was investigated during the Polarstern cruise ANTXXIV-3 ZERO&DRAKE. The speciation and distribution of iodine (iodate and iodide) in seawater was examined across gradients of iron concentrations and phytoplankton abundance, ranging from an open ocean region along the Zero Meridian to the Weddell Sea and Drake Passage. Iodine cycling in high latitudes differs from that in low latitudes due to differences in the plankton community composition and the physicochemical characteristics. Iodate concentrations ranged between 400 and 450 nmol L(-1) from the surface to the bottom. Surface concentrations of iodide (17 to over 60 nmol L(-1)) were about an order of magnitude higher than below the pycnocline. The peak values of iodide lay nearly always within the euphotic zone and showed a weak, positive correlation with nitrite concentrations in the upper 200 m. In all vertical profiles a pronounced sub-surface maximum in iodide appears between 50 and 200 m depth indicating an iodide drawdown at the near surface. Iodide distribution in the Weddell Sea showed elevated levels in Weddell Sea Bottom Water (WSBW) indicating slow oxidation kinetics and the potential for iodide as a tracer of WSBW formation. (C) 2011 Elsevier Ltd. All rights reserved.

Neonatal iodine deficiency: clinical aspects.

Abstract: Iodine is a trace element which is essential for the synthesis of thyroid hormones. The thyroid hormones, thyroxine (T4) and 3,5,3'-triiodothyronine (T3), are necessary for adequate growth and development throughout fetal and extrauterine life. The iodine intake of newborns is entirely dependent on the iodine content of breast milk and the formula preparations used to feed them. An inadequate iodine supply might be especially dangerous in the case of premature babies. The minimum recommended dietary allowance (RDA) for different age groups has recently been revised. The iodine intake required is at least 15 microg/kg/day in full-term infants and 30 microg/kg/day in preterms. The iodine content of many evaluated preparations for feeding premature infants appears to be inadequate. Premature infants are now in a situation of iodine deficiency, precisely at a stage of psychomotor and neural development which is extremely sensitive to alterations of thyroid function.