多壁碳纳米管/壳聚糖复合材料对水中染料的吸附

Adsorption of dyes in water by multiwall carbon nanotubes/chitosan composite

随着我国印染工业的快速发展,大量印染废水随之产生。印染废水具有色度高、难降解有机物浓度高、水质波动大等特点,对环境和人类健康造成危害。采用碱液沉积交联法制备多壁碳纳米管/壳聚糖复合材料(MWCNTs/CS),对二甲酚橙和茜素红染料模拟废水进行吸附处理,考察不同制备条件对吸附性能的影响。结果表明:多壁碳纳米管与壳聚糖质量比为1∶4、交联剂戊二醛投加量为2.5 mL、交联温度为50℃、交联时间为5 h时,制得的复合材料吸附效果最好。MWCNTs/CS对茜素红的最大吸附量可达291.44 mg/g,对二甲酚橙的最大吸附量可达263.59mg/g。2种染料的吸附过程符合拟二级动力学模型,以化学吸附为主,为自发放热过程。Freundlich吸附等温线能较好地拟合该吸附过程,n大于1,表明吸附过程为优惠吸附。

With the rapid development of printing and dyeing industry in China,a large amount of printing and dyeing wastewater is produced.The printing and dyeing wastewater is characterized by high chroma,high concentration of difficultly degradable organic compounds and high fluctuation of water quality,which poses a risk to environment and human health.Multiwall carbon nanotubes/chitosan composite(MWCNTs/CS)were prepared by alkali deposition cross-linking method to adsorb xylenol orange and alizarin red simulated wastewater,and the effects of different preparation conditions on the adsorption performance were investigated.The results showed that the best adsorption performance of composite was achieved when mass ratio of MWCNTs to CS was 1∶4,the dosage of glutaraldehyde was 2.5 mL,the cross-linking temperature was 50℃and the cross-linking time was 5 h.The maximum adsorption capacity of MWCNTs/CS was up to 291.44 mg/g for alizarin red and 263.59 mg/g for xylenol orange.The adsorption of MWCNTs/Cs on the two dyes was in accordance with the pseudo secondary kinetic model,which was dominated by chemisorption as a spontaneous exothermic process.The Freundlich adsorption isotherm was good fit for the adsorption process with constant n>1,indicating that the adsorption process is preferential.