Development Of New Adsorbent For Removal Of Iodide In Water Treatment

Nuclear power is one of the most important guarantees for China’s energy strategy.However,the iodine nuclide generated from the daily operation of nuclear power plants is extremely easy to diffuse,and it is one of the most difficult radionuclides to get rid of.Therefore,this dissertation intends to develop a new adsorbent to deal with the emergency accidents caused by the pollution of radioactive iodide.In this dissertation,a new adsorbent Cu/Ag-C for removal of iodide was synthesized by a one-step hydrothermal synthesis method.By monofactor analysis and orthogonal tests,the factors affecting the synthesis for the adsorbent was determined and follows the order of the mass ratio of Cu:Ag:C,synthesis time,synthesis temperature.The optimal synthesis condition determined from the tests were Cu:Ag:C mass ratio of 1:1:5,synthesis temperature of 220℃ and synthesis time of 3h.In addition,the morphological characteristics,elemental composition,potential of zero point and stability of the adsorbent Cu/Ag-C were analyzed,which showed the adsorbent Cu/Ag-C was brown powder with even particle size and large specific surface area,and Cu₂O and Ag particles sizes of 50～100 nm was loaded with uniform distribution on the surface.At p H>10.8,the zeta potential was positive.The adsorbent Cu/Ag-C showed great stability in the p H range of 5-9.This dissertation studied the adsorption mechanism and adsorption performance of the adsorbent Cu/Ag-C for simulated radioactive I^-.The adsorption mechanisms of the adsorbent Cu/Ag-C include exchange adsorption and chemisorption.The adsorption conformes to the pseudo-second-order kinetic model,and the adsorption isotherm conformed to the Langmuir isotherm.The adsorption reached equilibrium at120 min,and at 288,298 and 308 K,the maximum adsorption capacity was 59.2,69.0and 78.7 mg/g,respectively.When the initial I^-was 1.0 mg/L,the distribution coefficient of I^-reached 1.86×10⁶m L/g;when the dosage of adsorbent was 1.0 g/L,the removal rate reached 99.9%.The applicable range of p H values was 3～9,and the strong alkaline was not conducive to adsorption.In addition,it was determined by the results of desorption tests that the desorption of I^-can be ignored（the desorption rate was 1.8%）.By searching and comparing the literatures,Cu/Ag-C is provided with higher I^-adsorption capacity than other adsorbents.It could remove I^-from radioactive wastewater quickly,efficiently and selectively,and has potential application value in the emergency treatment of radioactive iodine wastewater in emergency nuclear accident.