Study On Properties And Mechanism Of Adsorption Of U(?) By Modified Graphite Phase Carbon Nitride

With the development of nuclear science,nuclear waste containing uranium has increased,producing a large amount of low-concentration uranium-containing wastewater,which has a serious impact on the environment and human health.As a simple,efficient,inexpensive,and no secondary pollution method,the adsorption method has become a hot topic in current research.In this paper,two functionalized materials were prepared by using melamine as raw material.Through their adsorption experiments on simulated low-concentration uranium-containing wastewater,the adsorption performance and adsorption mechanism of uranium by two materials were studied.The obtained research results are as follows:?1?The graphite oxide phase carbon nitride?OCN?nanomaterials were prepared by acid etching and oxidation treatment.The adsorption-desorption performance of OCN on U???in water was investigated.The effects of solution pH,temperature,OCN dosage,reaction time,initial concentration of U???on the adsorption of U???by OCN were investigated,and the adsorption mechanism was discussed.The results showed that OCN had a good adsorption effect on U???.At pH=5,30°C,the initial concentration of U???was 10 mg/L,and the dosage of OCN was 200 mg/L.The adsorption rate of U???is 98.9%,which is about 42%higher than that of unmodified graphite phase carbonitride?g-C₃N₄?.The adsorption reaction reaches adsorption equilibrium at 10 min,30°C.The theoretical maximum adsorption capacity is 278 mg/g.pH is an important factor affecting the adsorption of U???by OCN.Temperature and other factors have little effect on the adsorption of U???.The quasi-second-order kinetic equation and the Langmuir model fit the adsorption process well,and the adsorption process of U???by OCN is a spontaneous endothermic process.EDS shows that U element appears on the surface of the material after adsorption,indicating that U is successfully adsorbed on the surface of the material.The comparison of the infrared spectrum before and after adsorption shows that—NH₂,C—N,association—OH?C=O?C—O,etc.are OCN adsorption U???The main adsorption sites in the process.Adsorption desorption experiments show that OCN has good reusability.Polyaniline/graphite oxide phase carbon nitride?PANI/OCN?composites were prepared by in-situ polymerization of carbon monoxide?OCN?and polyaniline.The adsorption of U???in water by PANI/OCN was investigated.Desorption performance.The effects of solution pH,temperature,PANI/OCN dosage,reaction time,initial concentration of U???on the adsorption of U???by PANI/OCN were investigated,and the adsorption mechanism was discussed.The results showed that PANI/OCN had a good adsorption effect on U???.At pH=5,30°C,U???initial concentration was 10 mg/L,and ionic strength was 0.01mol/L NaNO₃,PANI/OCN When the dosage is 200mg/L,the adsorption rate of PANI/OCN to U???is 98%,the adsorption reaction reaches the adsorption equilibrium in 10 min,and the theoretical maximum adsorption capacity at 30°C is 322.6 mg/g.pH is an important factor affecting the adsorption of U???by PANI/OCN.The influence of ionic strength and temperature on the adsorption of U???is small,indicating that PANI/OCN adsorption U???is mainly affected by the surface interaction of the inner sphere.The BET results indicate that the specific surface area of the material is greatly increased after compounding.FTIR and XPS analysis indicated that the nitrogen-containing oxygen-containing functional groups on the surface of the composites were involved in the adsorption of U???.The quasi-second-order kinetic equation and the Langmuir model fit the adsorption process well,and the adsorption process of U???by PANI/OCN is a spontaneous endothermic process.Adsorption desorption experiments show that PANI/OCN has good reusability.