| The demand for uranium resources increased with the rapid development of nuclear energy.In uranium mining and uranium production,different types of uranium-containing wastewater are produced,which inevitably poses potential risks and threats to natural environment and human health.Therefore,the removal and recovery of the U(Ⅵ)is necessary.Shrimp waste can be used as food for aquaculture or breeding animals.It is generally disposed in landfill,high sea or burned.Proper disposal of waste shrimp shells is one of the urgent problems to be solved in China.Shrimp shell powder has abundant functional groups on its surface which is a potential fixed material.However,there is still a lack of experimental data on its uranium removal performance.In this study,strong oxidant(potassium permanganate,hydrogen peroxide)was used to modify shrimp shell powder,and batch adsorption test was used to discuss the removal effect of U(Ⅵ)solution concentration,the dosage of modified shrimp shell powder,p H of U(Ⅵ)solution,adsorption time and other factors on U(Ⅵ)in water,and adsorption isotherm and adsorption kinetics were analyzed.The results show that p H value greatly influenced U(Ⅵ)adsorption by modified shrimp shell powder.The amount of U(Ⅵ)adsorption under the U(Ⅵ)solution concentration of 10 mg/L reached maximum(48 mg/g)when the p H is 3,the content of hydrogen peroxide shrimp shell powder is 0.2 g/L,and adsorption time is120 min.However,the amount of U(Ⅵ)remove rate under the U(Ⅵ)solution concentration of 10 mg/L reached maximum(95%)when the p H is 2,the content of shrimp shell powder is 0.6 g/L,and adsorption time is 120 min.The removal of U(Ⅵ)by modified shrimp shell powder conforms to the quasi-first-order kinetic equation and Freundlich adsorption isotherm model.The Box-Behnken center combination test is used to optimize U(Ⅵ)modified shrimp shell powder on water removal rate of removal conditions and to build the 3d surface model,analyze U(Ⅵ)solution concentration,modification of shrimp shell powder adding quantity,U(Ⅵ)interaction between solution p H.Modification of shrimp shell powder adding quantity and p H has a significant effect on the U(Ⅵ)removal rate(P < 0.05).U(Ⅵ)initial concentration and modified shrimp shell powder dosing quantity,initial concentration and p H value were no significant interactions.In addition,the U(Ⅵ)removal mechanism was characterized by using SEM,XRD,XPS and FTIR modern characterization methods..FTIR analysis showed that the main functional groups are hydroxyl and amine.XPS analysis shows that U(Ⅵ)and U(Ⅳ)mixture was precipitated on the surface of shrimp shell powder.These results showed that the removal rate of U(Ⅵ)in water was higher by hydrogen peroxide modified prawn shell powder,so the modified prawn shell powder could be used as a promising adsorbent. |
