Heavy metal removal using SiO2-TiO2 binary oxide: experimental design approach

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• 作者：Adel A. Ismail ; Ayman A. El-Midany ; Ibrahim A. Ibrahim and Hideyuki Matsunaga
• 关键词：TiO2 ; SiO2 ; Sorption ; Heavy metals ; Ni2+ ; Cd2+ ; Statistical design
• 刊名：Adsorption
• 出版年：2008
• 出版时间：February, 2008
• 年：2008
• 卷：14
• 期：1
• 页码：21-29
• 全文大小：636.9 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Surfaces and Interfaces and Thin Films
  Industrial Chemistry and Chemical Engineering
  Engineering Thermodynamics and Transport Phenomena
  
• 出版者：Springer Netherlands
• ISSN：1572-8757

文摘

Sorption of Ni2+ and Cd2+ as heavy metals ions at the interface of the binary oxide TiO₂-SiO₂ was investigated. In addition, physical properties of TiO₂-SiO₂ matrices such as BET surface area, X-ray diffraction, and point of zero charge (pH_PZC) were measured. Statistical design of experiments was applied to find the conditions of sorption at which the maximum heavy metal removal was achieved. A second order polynomial function was used to correlate the independent variables (pH, metal ion concentration, and shaking time) and response (heavy metal removal). Values of regression parameters were determined by the computer program, Design expert? (Stat-Ease Inc.). The quality of fit of the polynomial model equation was expressed by the regression coefficient R 2. The sorption results showed that the pH is the most significant factor. In turn, the sorbed percentage reached 100% at high initial concentration and long shaking times due to formation of hydroxyl compounds between the ions and TiO₂-SiO₂ matrices. The results show that there is a Gaussian (normal) distribution of residuals (squared differences between experimentally observed and predicted values from the model), and also that the differences between observed and predicted values are in the range of ±5%. These indicate that experiments were well-conducted and the results have no significant error.