Comparison of adsorption ability of multiwalled carbon nanotubes modified by different Sodium Hypochlorite concentration – case of copper

• Main Authors: Wang, Wei-Jhih, 王瑋智
• Other Authors: TSAI, Yung-Pin
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/44003308190915650199

碩士 === 國立暨南國際大學 === 土木工程學系 === 97 === In this study Multi-walled Carbon Nanotubes (MWCNTs) were modified by different NaOCl concentration (1％、3％、5％、7％) for enhancing divalent metal ions (copper) adsorption in a aqueous solution. In oxidized process, MWCNTs recovering efficiency decreased with the increase of NaOCl concentration. The surface nature of the MWCNTs modified by NaOCl was changed and a great amount of carbon-containing defects along the surface of CNTs was produced which providing some functional groups, increasing surface charges and chemical adsorption sites, and then being benifical to the adsorption of the metal ions Cu2+. It was found that the order of the adsorption capacity for Cu2+ ions at 60 mgL-1 of initial concentration condition was 5%＞3%＞1%＞7%＞PAC＞Raw. The data set were statistically tested by one-way ANOVA and showed that the adsorption capacity of MWCNTS modified by NaOCl was significantly greater than those of RAW-CNTs and PACs (p<0.05). It implied that the pre-treatment of MWCNTs by NaOCl could enhancement the adsorption of Cu2+. The statistical test result also showed that the adsorption capacity of MWCNTs modified by 5% NaOCL was significantly greater than those by 1% and 7% NaOCl (p=0.008 and 0.047, respectively). However, no significant difference was found between 5% and 3% (p=0.226). In batch experiments, it was found that for Cu2+ ions the adsorption capacity of the MWCNTs modified by NaOCl increased with the increase of the temperature and pH values. Ionic strength also significantly affected the adsorption capacity of MWCNTs modified by NaOCl for Cu2+ ions. The kinetic behavior of sorption process of MWCNTs modified by NaOCL for Cu2+ ions was well described by the pseudo-second-order model. The maximum adsorption capacities of MWCNTs for Cu2+ ions obtained by Langmuir model at 25℃were 10.99, 16.64, 18.15, 14.27 mg/g for the MWCNTs modified by 1%, 3%, 5% and 7% NaOCL, respectively. The MWCNTs modified by 5% NaOCL had the best performance on Cu2+ ions sorption. In summary, it could be concluded in this study that the MWCNTs modified by NaOCl had a good sorption capacity for divalent copper metal ions. However, the MWCNTs would be disintegrated and consumed if the concentration of NaOC is too high.