| With the rapid development of society,the level of industrialization is getting higher and higher,and the industrial waste water is also increasing,which causes serious pollution to the environment.In order to minimize the destruction of human living environment,dealing with industrial waste water has become a hot issue in recent years.How to deal with wastewater containing heavy metal ions has become a major problem.Extraction method,ions exchange method,the traditional chemical precipitation method have a high cost,poor absorption effect,easy to cause two pollution and other defects.In recent years,researchers have been concerned about the biological adsorption technology to make up for the shortcomings of the traditional treatment methods,which are of the advantages of efficient,safe,cheap,easy and so on.Based on the preliminary research of our laboratory,this paper continued to use Fusarium sp.# ZZF51,a mangrove endophytic fungus as the research substrate to synthesize the fungus materials functionalizedby amidoxime-guanidine and double amidoxime to improve its uranium(Ⅵ)adsorption capacity.Different instrumental techniques such as infrared spectroscopy,thermogravimetric analysis,scanning electron microscopy and nitrogen adsorption desorption were employed for the characterization of the manufactured materials,and theirs properties of removal uranium(Ⅵ)were studied to find out the optimum conditions for adsorption uranium(Ⅵ).The adsorption model and adsorption mechanism were also explored to provide reference for the industrial treatment of uranium(Ⅵ)wastewater.The main contents are as follows:In the first chapter,the general situation of uranium resources in the world and its pollution situation were described,the traditional treatment methods of wastewater containing heavy metal ions were summarized,and the biosorption process was briefly introduced.The research status at home and abroad of the compounds containing amidoxime/guanidine functional groups in heavy metal wastewater treatment were studied,and the research significance,content,technical route of the paper were introduced.The second chapter,the reagents and equipment to be used in the course of the experiment,cultivation and collection process of fungus,the specific operation method of the adsorption experiment,the characterization methods of adsorption and the adsorption thermodynamics models and kinetic models were introduced.The third chapter,the synthesis process of marine fungus materials functionalized by amidoxime-guanidine groups(ZZF51-GPTS-DCDAAM)and adsorption properties from uranium(Ⅵ)solution were studied.Different instrumental techniques were employed for the characterization of the manufactured materials and materials after adsorption,the results show that compared with the unmodified fungus,the surface of the synthesized material was rough,and the binding sites and voids increased.During the adsorption process,hydroxyl groups,amino groups and amidoxime groups are involved in the adsorption of uranium(Ⅵ).The ability of removal uranium(Ⅵ)by modified material was optimized using response surface methodology(RSM).The experimental results showed the maximum adsorption capacity for the synthesized materials was 230.78 mg g-1 at the following optimization conditions: solid-liquid ratio 150 mg L-1,p H 5.13,uranium(Ⅵ)initial concentration 40 mg L-1,and equilibrium time 122.40 min.More than 85% of the absorbed uranium(Ⅵ)could be desorbed by 0.5 or 1.0 mol L-1 HCl,and the modified mycelium could be reused at least 5 times.The thermodynamic experimental data of adsorption uranium(Ⅵ)could fit better with Langumir and Freundlich isotherms models,and the pseudo-second-order model was better to interpret the kinetics process.The fourth chapter,the preparation process of containing double amidoxime-based claw-like functional material(ZZF51-GPTS-DAMN-AM)was introduced.The unmodified fungus,modified fungus,and material after adsorption were characterized by a series of characterization methods.The results showed that,amidoxime group were successfully grafted onto the fungus and provides for uranium(Ⅵ)adsorption sites;amidoxime group,amino group and hydroxyl group were contributed to the adsorption.In the study of the adsorption properties of materials,the influence of solid to liquid ratio,initial concentration of uranium,initial p H value and reaction time on the adsorption capacity of uranium was studied by single factor experiment.Based on the results of single factor experiment,orthogonal experiment was used to optimize the adsorption conditions.The experimental results show that the maximum adsorption capacity is 370.85 mg g-1 while the solid-liquid ratio is 100 mg L-1,the initial concentration is 40 mg L-1,the initial p H value is 6 and the reaction time is 110 min.ZZF51-GPTS-DAMN-AM was desorbed with 1 mol L-1 HCl solution,and the material was repeated after repeated experiments.After 5 times of desorption,the adsorbent still has a large adsorption capacity,which proves that the adsorbent has a good reuse rate.Langmuir,Freundlich,Temkin three adsorption isotherm models were used to fit the experimental data.It was found that the linear correlation coefficient(R2)of Langmuir and Freundlich isothermal adsorption equations were more than 0.99.Which were close to and higher than Temkin adsorption model,result showed that in the process of adsorption,adsorption monolayer and double layer adsorption were existed.The kinetic results show that the kinetic process was in good agreement with the pseudo-second-order model,and the R2 value was 0.9999.The modified fungus materials exhibited the better sorption capacity for uranium(Ⅵ)in comparison with raw biomass should be attributed to the strong chelation of amidoxime to uranium(Ⅵ)ions.In the fifth chapter,the experimental results are summarized in detail,and the future development direction of uranium containing wastewater treatment is also discussed. |
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