磁性CS-Y负载FA复合材料对偶氮染料的超高效吸附

Super Efficient Adsorption of Polyazo Dyes on Magnetic CS-Y-loaded FA Composite

采用溶胶-凝胶法制得一种新型磁性壳聚糖(CS)-钇Y(Ⅲ)负载粉煤灰(FA)复合材料(CS-Y-FA@Fe_(3)O_(4)),用于偶氮染料直接棕95(DB-95)的吸附,探讨了重要吸附条件和吸附机理,评估了吸附剂效能。结果表明,当吸附剂投加量为0.075 g、自然pH的染料溶液起始浓度为5000 mg/L时,于298 K下CS-Y-FA@Fe_(3)O_(4)对DB-95的吸附速率极快,15 min达到平衡,吸附量和去除率分别可达1585 mg/g和95.1%,比FA的吸附量增大16.6倍。吸附过程符合拟二级速率方程,染料吸附行为能分别用Freundlich和Dubinin-Radushkevich模型描述。热力学结果表明了吸附反应的自发放热性质。对吸附染料前后的CS-Y-FA@Fe_(3)O_(4)进行SEM、FTIR、UV-Vis和XPS分析,结果表明,吸附剂与DB-95分子发生相互作用是通过物理和化学吸附。作为一种低成本磁性复合材料,CS-Y-FA@Fe_(3)O_(4)能在很宽pH范围内对高浓度染料废水进行有效净化,并完成固液快速分离。

A novel magnetic Y(Ⅲ)-chitosan(CS)-loaded fly ash(FA)composite(CS-Y-FA@Fe_(3)O_(4))was prepared by sol-gel method,and directly used for adsorption of Direct Brown 95(DB-95)dye in simulated wastewater.The important adsorption conditions and mechanism were explored,and the composite performance was evaluated.The results show that the adsorption rate of DB-95 onto CS-Y-FA@Fe_(3)O_(4)is very fast,and the adsorption equilibrium is reached in 15 min.When the adsorbent dosage is 0.075 g and the initial dye concentration with natural pH is 5000 mg/L,the adsorption capacity and removal rate at 298 K can reach 1585 mg/g and 95.1%,respectively,which is 16.6 times higher than that of FA.The pseudo-second-order rate model fits the adsorption process at different temperatures well.The dye adsorption behavior can be described by Freundlich and Dubinin radushkevich(D-R)models,respectively.The thermodynamic results indicate the adsorption reaction is spontaneous and exothermic.SEM,FTIR,UV-Vis and XPS analysis of CS-Y-FA@Fe_(3)O_(4)before and after dye adsorption showed that DB-95 dye interacted with the adsorbent mainly through physical and chemical adsorption.CS-Y-FA@Fe_(3)O_(4)composite with the magnetism and low cost can be used for ultra-efficient purification of high-concentration dye wastewater in a wide range of pH and quickly complete solid-liquid separation by external magnetic field.