Preparation Of Copper Based Layered Compounds And Implication To Removal Of Different Forms Of Iodine

The continuous development of industryhas caused the increase of iodine concentration in the water body, which produces iodine pollution. Iodine is the essential element of the human body, but excessive iodine will be enriched in the thyroid, causing harm to the human body. And radioactive iodine will aggravate the severity of iodine pollution. Therefore, the development of new, exclusive iodine adsorption material has an important significance. Layered metal hydroxide is a new kind of supramolecular material, because of its unique layered structure, physical and chemical properties, as an adsorbent, especially the anion adsorbent has some special advantages. Now most of the study onlayered metal compounds are focused on the double hydroxides. The study on iodine removal is few, and the iodide and iodate adsorption capacity in the reported studiesare very low.Especially, the studyonmethyl iodide removal is rarely reported. Therefore, We had prepared copper based metal layered compounds?Cu/Mg/Al-LDHs? using coprecipitation method. The adsorption capacity and adsorption mechanismof the calcined product?Cu/Mg/Al-CLDH? to iodine had been conducted.The result had practical significance to copper based layered compounds using in treatment of wastewater contaminated by iodine.The main research work and achievements are:?1?The Cu/Mg/Al-LDHs was prepared by the coprecipitation method.The optimum process was: the molar ratio of Mg to Al was 3:1, the mixed solution of Mg²⁺ and Al³⁺ was 150 ml, the adding amount of 0.4 mol/ L Cu²⁺was 5 ml, 0.25 mol /L Na₂CO₃ was 300 ml. The mixed solution of Mg, Al and Cu added to the Na₂CO₃ solution with the speed of 1 dropsfor 2 to 3 seconds, the drop time was about 2 h.The pH value was9-10 adjusted by1 mol/L HNO₃ and 1 mol/L Na OH solution, reaction was under theroom temperature, then the solution was agedfor 24 h under 60?. The precipitation was filtrated, washed and dried. The Cu/Mg/Al-CLDH was preparedby calcineding Cu/Mg/Al-LDHs in a muffle furnace for 3 h at 400 ?. The Cu/Mg/Al-LDHs and Cu/Mg/Al-CLDH were characterized by FT-IR, XRD, SEM, BET and TG-DTG. The results showed that the Cu/Mg/Al-LDHs had the typical layered structure,the surface was uniform and porous.The layered structure of Cu/Mg/Al-CLDH disappeared owing to calcination, but its laminate retained.The layer structure could be recovered after adsorbingthe iodine.?2?The adsorption performance of Cu/Mg/Al-CLDH to I^-, IO₃^-, CH₃I was studied.The best condition for I^-was: adsorption time was 60 min, solid-liquid ratio was 1:250, adsorption temperature was 35?, the adsorption of pH was 7. The optimum condition for IO₃^- was: the adsorption time was 120 min, the solid-liquid ratio was 1:250, the adsorption temperature was room temperature, and the adsorption of pH was 7. The optimum conditionfor CH₃I was: the adsorption time was 30 min, the solid-liquid ratio was 1:250, the adsorption temperature was room temperature, and the adsorption pH was 8. Under the optimum conditions, the saturated adsorption capacity of Cu/Mg/Al-CLDH to I^-, IO₃^-, CH₃I were 279.15 mg/g, 265.90 mg/g, 200.92 mg/g, respectively, and were much higher than that of Mg/Al-CLDH for I^-, IO₃^-, CH₃I.?3? The adsorption mechanism of Cu/Mg/Al-CLDH to I^-, IO₃^-, CH₃I was discussed. The adsorption of Cu/Mg/Al-CLDH to I^-, IO₃^-, CH₃I were in accord with the Langmuir isotherm equation and the Freundlich isotherm equation. The adsorption processincluded electrostatic interaction and chemical reaction. The adsorption force and the degree of difficulty were in accordance with the order of I^->IO₃^->CH₃I.