Studies On Synthesis Of Hydrothermal Carbon Microspheres From Lignin By Template Method And The Adsorption Properties Of Uranium

Uranium is the most important nuclear fuel of nuclear power.However,a large number of radioactive waste water will be produced during the utilization,mining and metallurgy of uranium,which cause great harm and damage to the ecological environment and human health.The treatment of radioactive waste water is attracting more and more attention from all over the world.The research and development of radioactive waste water treatment and uranium recycling materials and technologies have enabled radioactive waste water to be effectively treated and discharged.At the same time,the important uranium resources in the waste water can be recycled,which has become a research hot spot in radioactive chemistry and environmental chemistry.Adsorption method has attracted the attention of scientists because of its economy and simple process/operation.In this project,a novel adsorbent of carbon materials was successfully prepared by hydrothermal and template method,using sodium lignosulfonate as a raw material and cetyltrimethylammonium bromide/hydrotalcite as a template agent.The morphology and structural properties of the novel carbon materials were systematically studied.At the same time,the adsorption performance of uranium in radioactive waste water was studied using a batch adsorption experiment.The main contents are listed as follows:(1)A novel adsorbent of mesoporous carbon materials(Carbon-LSs+CTAB)was successfully prepared by hydrothermal and template method,using sodium lignosulfonate(LSs)as a raw material and cetyltrimethylammonium bromide(CTAB)as a template agent.Scanning electron microscopy(SEM)analysis showed that the microscopic morphology of the material was spherical and cotton-like;BET surface area analysis showed that the addition of the template agent increased the specific surface area of the carbon material;The analysis of XPS and FTIR reveals the Carbon-LSs+CTAB possesses a large amount of oxygen-containing functional groups.These characteristics of the carbon materials will facilitate its removal of uranium ions in the wastewater.(2)The uranium adsorption performance of the mesoporous carbon material(Carbon-LSs+CTAB)was studied by using batch adsorption experiments.The results showed that the optimum adsorption conditions of Carbon-LSs+CTAB were T=289.15 K,p H=5.5,m=0.04 g,and t=24 h,and the adsorption process accorded with the pseudo-second-order kinetic model and nonlinear Freundlich isothermal adsorption model.(3)The carbon material(Carbon-LSs+HT)was prepared by the method of hydrothermal carbonization and template method with sodium lignosulfonate as the raw material and hydrotalcite as the template agent.SEM characterization showed that the microscopic morphology of the carbon material was spherical.BET analysis showed that the addition of the hydrotalcite templating agent increased the specific surface area of the carbon material.The results of batch adsorption experiments showed that the maximum adsorption of uranium for Carbon-LSs+HT carbon materials was167.50 mg/g under normal temperature conditions,p H 5.0 and adsorption dose of 0.02 g.The adsorption of uranium on Carbon-LSs+HT carbon materials conforms to the pseudo-second-order kinetic model and Langmuir isotherm model.(4)Both Carbon-LSs+CTAB and Carbon-LSs+HT carbon materials contain a large amount of oxygen-containing functional groups(-COOH/-C-OH)on the surface.The mechanism of uranium adsorption on the two carbon materials is mainly oxygen-containing functional groups.The uranium ions can participate in coordination reaction with two oxygen atoms in hydroxyl of carbon materials or can participate in ion-exchange reaction with the hydrogen ions on the oxygen-containing functional groups to achieve uranium removal.