多孔MnO_(2)-Fe_(3)O_(4)壳聚糖微球用于增强类Fenton降解染料废水的研究

Enhanced Fenton-like degradation of dye wastewater by porous MnO_(2)-Fe_(3)O_(4)/chitosan microspheres

将壳聚糖与金属盐混合溶液滴入碱性溶液中,采用一步法制备了金属壳聚糖微球(MnO_(2)-Fe_(3)O_(4)/CS),并用于刚果红(CR)的类Fenton降解。结果表明,与单金属壳聚糖微球(MnO_(2)/CS、Fe_(3)O_(4)/CS)相比,MnO_(2)-Fe_(3)O_(4)/CS具有更好的催化活性;在最佳条件下(50 mg/L CR,pH=7,0.9 mol/L H2O_(2),2.0 g/L催化剂,60 min),CR的去除率达到100%。MnO_(2)-Fe_(3)O_(4)/CS的高活性归因于其较大的比表面积和孔体积,特殊多孔结构有利于反应物的吸附/扩散和活性位点的暴露;Mn-Fe双金属之间的协同作用促进了电子传递,有效提高了催化活性。金属壳聚糖微球可以很容易地从反应体系中收集,重复使用5次后仍然保持较高催化活性(88.2%)。

This research focuses on the preparation of metal chitosan microspheres using a one-step method,involving the dropping of a chitosan-metal salt mixture into an alkaline solution.These chitosan microspheres contain welldispersed nanoparticles of MnO_(2)and Fe_(3)O_(4)(MnO_(2)-Fe_(3)O_(4)/CS)and were used for the Fenton-like degradation of Congo red(CR).Results showed that the catalytic activity of MnO_(2)-Fe_(3)O_(4)/CS was better than that of monometallic chitosan microspheres(MnO_(2)/CS,Fe_(3)O_(4)/CS).Under the optimized conditions(50 mg/L CR,pH=7,0.9 mol/L H2O_(2),2.0 g/L catalyst,60 min),the removal of CR reached 100%.The improved performance of MnO_(2)-Fe_(3)O_(4)/CS can be attributed to its large specific surface area,high pore volume,and unique porous structure.These characteristics promote the adsorption/diffusion of reactants and the exposure of active site.Moreover,the synergistic effect of Mn and Fe bimetal enhances electron transfer and greatly improves catalytic activity.In addition,the metal chitosan microspheres can be easily collected from the solution and maintain a high activity(88.2%)even five times of reuse.