2024-03-28T14:39:23Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/580122022-11-17T02:08:08Zhdl_2115_20045hdl_2115_139Removal of iodide from water by chlorination and subsequent adsorption on powdered activated carbonIkari, Mariya1000000173790Matsui, YoshihikoSuzuki, YutaMatsushita, TakuShirasaki, Nobutakaopen accessIodideIodateSPACPACNOM519Chlorine oxidation followed by treatment with activated carbon was studied as a possible method for removing radioactive iodine from water. Chlorination time, chlorine dose, the presence of natural organic matter (NOM), the presence of bromide ion (Br-), and carbon particle size strongly affected iodine removal. Treatment with superfine powdered activated carbon (SPAC) after 10-min oxidation with chlorine (1 mg-Cl-2/L) removed 90% of the iodine in NOM-containing water (dissolved organic carbon concentration, 1.5 mg-C/L). Iodine removal in NOM-containing water increased with increasing chlorine dose up to >0.1 mg-Cl-2/L but decreased at chlorine doses of >1.0 mg-Cl-2/L. At a low chlorine dose, nonadsorbable iodide ion (I-) was oxidized to adsorbable hypoiodous acid (HOI). When the chlorine dose was increased, some of the HOI reacted with NOM to form adsorbable organic iodine (organic-I). Increasing the chlorine dose further did not enhance iodine removal, owing to the formation of nonadsorbable iodate ion (IO3-). Co-existing Br- depressed iodine removal, particularly in NOM-free water, because hypobromous acid (HOBr) formed and catalyzed the oxidation of HOI to However, the effect of Br- was small in the NOM-containing water because organic-I formed instead of SPAC (median particle diameter, 0.62 gm) had a higher equilibrium adsorption capacity for organic-I than did conventional PAC (median diameter, 18.9 mu m), but the capacities of PAC and SPAC for HOI were similar. The reason for the higher equilibrium adsorption capacity for organic-I was that organic-I was adsorbed principally on the exterior of the PAC particles and not inside the PAC particles, as indicated by direct visualization of the solid-phase iodine concentration profiles in PAC particles by field emission electron probe microanalysis. In contrast, HOI was adsorbed evenly throughout the entire PAC particle.Elsevier2015-01-01engjournal articleAMhttp://hdl.handle.net/2115/58012https://doi.org/10.1016/j.watres.2014.10.021254627310043-1354Water research68227237https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/58012/3/HUSCAP%20iodine.pdfapplication/pdf679.28 KB2015-01-01https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/58012/2/Supplemental%20Material.pdfapplication/pdf655.67 KB2015-01-01