Study On Preparation And Uranium Absorption Characteristic Of Modified Gelatin/PVA Nanofiber Membrane

Uranium plays an important role in the development of nuclear industry as a strategic resource.The uranium content in seawater is much higher than that on land.Effective utilization of uranium resources in the ocean is of great significance to ensure the sustainable development of China’s nuclear industry.The separation and enrichment technology of uranium in seawater have always been one of the hotspots in the field of nuclear industry.Methods for extracting uranium from seawater include electrochemical,ion exchange,adsorption,flotation method and so on.The adsorption method is considered to be the most promising separation and enrichment technology under the condition of low concentration because of simple operation,high economic benefits and low environmental pollution.Adsorption materials are the key factor in determining the high performance adsorption process.This topic focuses on the key issues of the research and application of new environment friendly uranium adsorption materials,and carries out the research on the modified gelatin /PVA nanofiber membrane and its adsorption characteristics.Gelatin and polyvinyl alcohol(PVA)were used as the main matrix materials,and electrospinning technology was used to prepare nanocomposite fibers.Two kinds of new kelp-like nanofiber separation and enrichment membranes were created by compounding and loading calcium hydrogen phosphate and bayberry tannin(BT).The morphology and structure property were studied,simultaneously.The adsorption characteristics of uranium(VI)were studied by batch adsorption experiments and the mechanism was analyzed,several aspects of main content were as follows:1.The gelatin and PVA was used as the raw materials,and a new gelatin/polyvinyl alcohol composited dicalcium phosphate nanofiber band material(GPNB-DCP)was prepared by electrospinning technology.The electrospinning conditions of GPNB-DCP were studied.The effects of the ratio of gelatin,PVA and DCP,crosslinking time,crosslinker concentration and crosslinking temperature on the properties of GPNB-DCP nanocomposite fiber adsorbent were investigated.Scanning electron microscopy(SEM),Fourier transform infrared absorption spectroscopy(FT-IR),mechanical properties,water absorption and other analytical techniques were used to investigate the microstructure,material properties and synthesis reaction mechanism of the material.The results showed that the optimal synthesis process of nanofiber composite membrane was as follows: the mass ratio of gelatin and PVA was 4:6,the adding amount of DCP was 0.2 g,crosslinking time was 2 h,concentration of glutaraldehyde was 0.5.%,and crosslinking temperature was 40 °C.2.The uranium adsorption properties of GPNB-DPC fiber membrane materials were studied by batch adsorption experiments.The results showed that the optimal adsorption conditions of GPNB-BT were: T= 298.15 K,p H=5.0,m=0.02 g and t= 600 min,and the maximum adsorption amount was 226 mg/g.The adsorption process was consistent with the pseudo-second-order kinetics of linear and the Langmuir isothermal adsorption model of linear.The adsorption of uranium(VI)by GPNB-DCP is an endothermic,entropic,and spontaneous reaction process.3.The gelatin and(PVA)was used as the raw materials,and a new gelatin/polyvinyl alcohol immobilized tannins nanofiber band material(GPNB-BT)was prepared by electrospinning.In order to study the effect of electrostatic spinning on BT curing and uranium adsorption,the preparation technology factors on DCP immobilized onto GPNB-DCP was investigated and the effects of BT curing conditions on uranium adsorption by GPNB-BT material.The results showed that when the optimal ratio of gelatin and PVA was 4:6,the average diameter of fiber is the smallest.At the same time,the BT curing amount(236 mg/g)and adsorption capacity of GPNB-BT(170 mg/g)are the largest.The optimum condition of BT immobilized onto GPNB-BT was the concentration of BT was 10 mg/m L,soaking time was 240 min,crosslinking temperature of 50 ℃,concentration of glutaraldehyde was 0.2%,crosslinking time was 240 min.4.The uranium adsorption properties of GPNB-BT fiber membrane materials were studied by batch adsorption experiments.The results showed that the optimal adsorption conditions of GPNB-BT were: T= 298.15 K,p H=5.0,m=0.02 g and t= 600 min,and the maximum adsorption amount was 255 mg/g.The adsorption process was consistent with the pseudo-second-order kinetics of linear and the Langmuir isothermal adsorption model of linear.The adsorption of uranium(VI)by GPNB-DCP is an endothermic,entropic,and spontaneous reaction process.The adsorption process is endothermic,spontaneous and random.The nanofiber membrane was used to separation and enrichment of uranium in simulate seawater.The removal efficiency was higher than 90%,and GPNB-BT had a high adsorption capacity(7.2 g/g)for uranium.