Study On The Preparation Of Biocarbon-Chitosan Complex And Its Adsorption Performance On Low Concentration Uranium-Containing Wastewater

In the process of uranium mining,a large amount of waste water containing low concentration of uranium is produced,which will pose a serious threat to the ecological environment and human health.Because of its high efficiency,simple operation and low cost,adsorption method has become a research hotspot in the treatment of uranium-containing wastewater.Therefore,it is an important task to find economic,safe and efficient adsorptive materials.In this paper,biocarbon/chitosan?BC-CTS?composites were prepared by in-situ precipitation with coconut shell biochar?BC?and chitosan?CTS?as raw materials.The composites were characterized by SEM-EDS,BET,IR and XRD.The adsorption performance and adsorption mechanism of BC-CTS on low concentration uranium containing wastewater were studied.The following results were obtained:?1?Chitosan was coated on biochar by in situ precipitation method,and biochar-chitosan composite was obtained.The specific surface area and pore volume of the composite decreased,but the pore size increased.The results of elemental analysis showed that the mass fraction of N and H increased from 1.34%to 3.88%and 0.96%to 2.27%.?2?The adsorption properties of U???by biocarbon-chitosan composites were studied.The effects of initial uranium concentration,adsorption time,pH,temperature and interference ions on the adsorption of U???by BC-CTS were investigated.The results show that the adsorption rate of,U???can reach 94.85%when the dosage of pH=4.0,is 0.8g/L¹g/L and the adsorption equilibrium time is 200min.After 5cycles of adsorption analytical test,the adsorption rate can still reach about 88%.?3?Both the Langmuir model and the Freundlich model can fit the adsorption process of BC-CTS to U???well,but it is more in line with the Langmuir model,and the adsorption kinetic process accords with the quasi-second-order kinetic equation.?4?The vibrational shifts of-OH,-NH₂ and-COOH in the infrared spectra before and after adsorption were observed.EDS indicated that U element appeared after adsorption and some element contents?Na,Mg,Ca?changed before and after adsorption.There is no significant change in the?XRD?pattern after adsorption and there is no new precipitation.It is suggested that the adsorption mechanism of uranium by the biocarbonion-chitosan composite is ion exchange and coordination.