Study On The Removal Of Radio Nuclides From Seawater By Natural Materials

On March11,2011, Japan Fukushima happened serious nuclear safety accidents bythe impact of the earthquake and tsunami, and so far the high salt and radioactivewastewater has failed to be disposed properly. To develop an economic, efficientemergency treatment technology for high salt radioactive water become an important partof the security system of nuclear power. This paper studied the ion exchange, adsorption,coprecipitation between some simulatied nuclides on several lowcost materials, by meansof simulatied nuclide and simulation experiment. This article aims at providing basicsupport data for related application technology development, through the comprehensiveutilization of materials to remove simulatied nuclides from seawater.To achieve this purpose, this article selected the following three main types ofmaterials as the research object, include:(1) the silicate minerals, including all kinds ofnatural zeolite, synthetic zeolite and clay minerals;(2) iron-based materials, including ironoxide and iron hydroxide;(3) the calcium minerals, including calcite, aragonite andcalcium hydroxide by shell powder conversion. Before the experiment, using scanningelectron microscopy (SEM), X-ray diffraction, laser granularity instrument characterizedthe basic physical characteristics (surface morphology, crystal structure, particle sizedistribution). In the first place, experiments were conducted in the simple solution, forpreliminary screening of various materials. The results showed that:(1) the zeolitematerials has a better removal effect for Cs+and Sr2+, Pb2+, clay minerals has a betterremoval effect for Sb and U;(2) iron-based material due to its huge difference surfaceactivity for adsorption efficiency disparity, iron hydroxide has obvious removal efficiencyfor most simulatied nuclides except Cs+and Sr2+;(3) the calcium minerals, calciumcarbonate materials has a better removal effect for Mn, Co, Th, Pb, calcium hydroxide forMn, Co, Th, U adsorption effeciency is obvious.As the result of the above experiments, this work selected the NF-2, NF-4, NF-5,ZF-1, ZF-3, BKF-3, BKF-4, GLT-1, GLT-4, CaCO3, Fe(OH)3, Fe2O3as the research objectof the next step, which would be evaluated in seawater one by one. The results in seawater showed that:(1) natural zeolite materials has a better removal effect for Th, U, Cs;(2)artificial zeolite has a better removal effect for Mn, Co, Th, Pb;(3) clay plant-based has abetter removal effect for Th and U;(4) iron-based materials has higher removal efficiencyfor most simulatied nuclides except Cs+and Sr2+;(5) calcium carbonate minerals in Th, Uand Pb adsorption effect is obvious, the characteristics of calcium hydroxide similar toiron hydroxide. Related experimental results also showed that:(1) the salt in seawater forzeolite materials and clay mineral adsorption efficiency and removal effect of strontiumand cesium have a significant impact;(2) the effective removal for comprehensivesimulatied nuclides can’t realize by a single material.Combined with seawater experimental results, this article selected the BKF-3, NF-5,Fe(OH)3to conduct cross experiments. the experimental result showed that the removalefficiency of simulatied nuclides Mn, Co, Th, U and Pb can reach100%, the removalefficiency of Sb and Cs can reach60%. No matter adopt what kind of method, thesimulatied nuclides Sr was failed to be removed, which remains to be further studied.