酸改性粉煤灰Pb^(2+)吸附效应及机制探究

Adsorption effect and mechanism of Pb^(2+) by acid modified fly ash

粉煤灰为典型的燃煤废弃物,具有一定的重金属吸附能力。为提高其重金属吸附能力,采用酸改性法制备改性粉煤灰,通过SEM、FTIR、XRD等手段进行吸附剂表征,并探讨pH值、初始浓度、吸附剂投加量、接触时间等因素对吸附性能的影响。结果表明:1)2 mol/L硫酸改性可使粉煤灰孔隙结构增加,吸附容量提高1.45倍;2)吸附过程符合拟二级动力学模型,不同温度下吸附平衡数据符合Freundlich模型,最大吸附量可达到151.52 mg/g;3)热力学计算表明,改性粉煤灰吸附Pb^(2+)的过程为自发吸热过程。研究结果表明硫酸改性粉煤灰具有较高的Pb^(2+)吸附能力,可对其在重金属废水处理中的应用方式开展进一步探索。

As a typical coal burning waste,fly ash has certain adsorption capacity of heavy metals.In order to improve its adsorption capacity of heavy metals,modified fly ash was prepared by acid modification and characterized by means of SEM,FTIR and XRD.The effects of pH,initial concentration,adsorbent dosage,contact time and other factors on the adsorption performance were discussed.The results show that:(1)modification with 2 mol/L sulfuric acid can increase the pore structure and adsorption capacity of fly ash by 1.45 times;(2)the adsorption process conforms to the pseudo-second-order kinetic model,and the adsorption equilibrium data at different temperatures conforms to the Freundlich model,with the maximum adsorption capacity reaching up to 151.52 mg/g;(3)thermodynamic calculation shows that the adsorption process of Pb^(2+) by modified fly ash is a spontaneous heat absorption process.In conclusion,sulfuric acid modified fly ash has high Pb^(2+) adsorption capacity,and its application in heavy metal wastewater treatment can be further explored.