Synthesis Of Chitosan Adsorbent And Its Adsorption Of Gold Ions

Gold plays a very important role in jewelry processing,precision electronics,chemical catalysis and medical aviation.However,with the development of industry and economy,the demand for gold is increasing.Therefore,how to efficiently separate gold from low-grade ores and secondary resources has received widespread attention.In this paper,novel adsorbents were prepared by modified chitosan for the separation of gold ions.And studied the adsorption performance,adsorption behavior and adsorption mechanism of these three adsorbents.The main research content of this paper is as follows.(1)Firstly,three new chitosan-based adsorbents were prepared,namely amidinothiourea-modified chitosan(CS-GTU),cystamine dihydrochloride modified magnetic chitosan(CS-CDF)and chitosan-coated composites with different ratios of Mo S₂(CS-Mo S₂).The three adsorbents were characterized by SEM-EDS,FT-IR,XRD,VSM and XPS.(2)The effects of solution p H,adsorption time,ion concentration,adsorption temperature,coexisting ions and number of cycles were investigated.The results showed that the optimum p H of all three adsorbents was 5.0.The saturation adsorption amount of gold ions by CS-GTU was 690.28 mg/g.The saturation adsorption amount of gold ions by CS-CDF was 478.47 mg/g.The saturation adsorption amounts of gold ions by CS-Mo S₂-1,2,and 3 were 2012.46,2611.32,and 3108.79 mg/g,respectively.And these three chitosan-based materials have excellent selectivity and reusability.(3)The adsorption behavior of gold ions was studied by adsorption kinetics,adsorption thermodynamics and adsorption isotherms.The results showed that the interactions of CS-GTU,CS-CDF and CS-Mo S₂ with gold ions were all spontaneous heat absorption reactions,and the adsorption behaviors of gold ions were in accordance with the Langmuir and Pseudo-second-order models,so the processes belonged to monolayer homogeneous chemisorption.(4)The adsorption mechanisms of the three adsorbents were investigated by SEM-EDS,Zeta and XPS characterization.The results showed that the adsorption mechanisms of CS-GTU,CS-CDF and CS-Mo S₂ on gold ions were all chelation and electrostatic interactions.In conclusion,due to the high adsorption capacity,simple preparation process,fast adsorption kinetics,excellent selectivity and reusability,the three chitosan adsorbents have greater potential and application prospects in the field of gold ion recovery utilization.