Excellent adsorption and desorption characteristics of polypyrrole/TiO₂ composite for Methylene Blue

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• 作者：Jingjing Li^a ; Jiangtao Feng^a ; ^{fjtes@mail.xjtu.edu.cn} ; Wei Yan^a ; ^b ; ^{yanwei@mail.xjtu.edu.cn}
• 关键词：PPy ; PPy/TiO2 ; Composite adsorbent ; Dye adsorption ; Regeneration
• 刊名：Applied Surface Science
• 出版年：2013
• 出版时间：15 August, 2013
• 年：2013
• 卷：279
• 期：Complete
• 页码：400-408
• 全文大小：1510 K

文摘

P25 or self-prepared TiO₂ coated polypyrrole (PPy/P25 or PPy/TiO₂) composites as novel adsorbents were prepared. Their adsorption-desorption characteristics for Methylene Blue (MB) were comparatively investigated. X-ray photoelectron spectroscopy (XPS) showed that PPy/TiO₂ possessed higher doping level than PPy/P25. Thermogravimetric analysis (TGA) indicated that PPy/TiO₂ contained more PPy than PPy/P25. The results of water vapor adsorption suggested that the PPy/TiO₂ composite was more hydrophobic than PPy/P25. The adsorption results revealed that the composites pretreated in the solution with higher pH value exhibited larger adsorption capacities. The ionic concentration in MB solution slightly impacted the removal of MB by the PPy/TiO₂ composite. The adsorption equilibrium results showed that the adsorption of MB was completed in a short time of 30 min. Pseudo-second-order and Langmuir isotherm models were effectively employed to describe the adsorption behavior of MB. PPy/TiO₂ and PPy/P25 were found to have better removal ability for MB compared with pure PPy; especially PPy/TiO₂, on which the maximum adsorption amount was about 3.6 or 5.5 times higher than that of PPy/P25 or pure PPy, respectively. The thermodynamic analysis indicated that the adsorption of MB was spontaneous and endothermic in nature. The regeneration experiments exhibited that PPy/TiO₂ can be reused at least seven times without obvious loss of its original adsorption capacity. Electrostatic interaction, hydrogen bonding and hydrophobic interaction played the roles in MB adsorption performance. It is expected that the PPy/TiO₂ composite can be considered as a stable adsorbent for dye removal.