Preparation Of Functional Materials Based On CMC And Their Applications For Cesium Recovery

The efficient extraction and enrichment of cesium from underground brine is of great significance in the sustainable development of cesium resources in China.Among various inorganic absorbents,ammonium molybdate phosphate and potassium cuprous ferrocyanide received more attention for their high adsorption capacity and selectivity for cesium.However,the fine powder morphology and poor mechanical strength of ammonium molybdate phosphate and potassium cuprous ferrocyanide lead to the serious problems in the column operation and post-separation process in industry.To solve these problems,many studies have been made to immobilize ammonium molybdate phosphate and potassium cuprous ferrocyanide particles into supporters to obtain mechanically stable and easily separated particles.Hence,in this work,both ammonium molybdate and potassium copper cyanide composite adsorbents were prepared.The absorption performance of the composite adsorbents in the adsorption of cesium from synthetical brine were systematically investigated,and the kinetic and adsorption isotherm were also studied.The main contents are as follows:1.A highly stable potassium copper ferrocyanide-contained porous composite spheres(CMC-KCuFC)had been prepared using nitrogen,n-hexane or polyethylene glycol(PEG6000)as the pore formation agent through the cross-linked reaction of carboxymethyl cellulose sodium(CMC)aqueous solution contained potassium copper ferrocyanide(KCuFC)and Fe3+.This CMC-KCuFC was verified by XRD,FT-IR,SEM,EDX and BET.By comparing the specific surface area of series of prepared microspheres,the CMC-KCuFC composite using PEG6000 as the pore-foaming agent possessed the largest surface area of 33.9674 m2·g-1,and used as the best absorbent in our experiments.Optimizing experimental conditions in the adsorption of cesium were systematically investigated,including the pH of the solution,adsorbent dosage,contact time,initial concentration of Cs+,temperature and competitive ions.This porous CMC-KCuFC was stable under a wide range of pH values(2-10)as well as the solution with ammonium ion(NH4+),and the maximum adsorption capacity of Cs+ was up to 102.038 mg·g-1.In addition,the adsorption thermodynamic,kinetic and isotherm have been investigated,and the results suggested this adsorption process belongs to spontaneous endothermic chemisorption process.2.Ammonium phosphomolybdate composite particles was successfully synthesize through the cross-linked reaction of biocompatible and low-cost CMC solution embedded AMP with Fe3+ as cross-linking agents,and characterized by FT-IR,SEM and EDX.Series of batch experiments were investigated,and the results showed the maximum adsorption capacity of this CMC-AMP was 65.416 mg·g-1 in optimum conditions.In addition,under the coexistence of potassium ions,CMC-AMP still had a high partition coefficient for cesium.Furthermore,the CMC-AMP could be easily recycled and reused at least five times without obvious decrease in absorption activity and selectivity with 1 mol·L-1 NH4Cl as the eluent,and the adsorption capacity of CMC-AMP could be maintained at 64.683 mg·g-1 after five cycles.The adsorption thermodynamic parameters indicated the endothermic and spontaneous nature of the adsorption process.The nonlinear pesudo-second-order kinetic model was found to exhibit the best correlation with the adsorption results,and the equilibrium data was better described by the Freundlich isotherm equation.