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| Adsorption Characteristics of EDTA on α–Hemihydrate Desulfurization Gypsum Surface and Its Influence on Crystal Morphology |
| PENG Jiahui1, QU Jindong2, ZHANG Jianxin1, ZOU Chenyang1, CHEN Mingfeng1 |
1.College of Materials Science and Engineering, Chongqing University, Chongqing 400045
2.Faculty of Urban Construction & Environmental Engineering, Chongqing University, Chongqing 400045 |
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Cite this article:
PENG Jiahui QU Jindong ZHANG Jianxin ZOU Chenyang CHEN Mingfeng. Adsorption Characteristics of EDTA on α–Hemihydrate Desulfurization Gypsum Surface and Its Influence on Crystal Morphology. Chin J Mater Res, 2011, 25(6): 566-572.
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Abstract The adsorption characteristics of EDTA on α–hemihydrate desulfurization gypsum surface and its influence on crystalline habit and crystal morphology were studied by use of SEM, MICRO-FTIR, UV adsorption spectrophotometer and XPS technique. Its crystal modifying mechanism was also analyzed from the viewpoint of crystal growth. The results show that the adsorption of EDTA on α–hemihydrate desulfurization gypsum is chemical adsorption. The adsorption isotherms curve basically follows Langmuir equation, its max adsorption amount is 15.2mg and the thickness of adsorption layer 6.5 nm. The addition of EDTA evidently changes the crystalline habit and crystal morphology of α–hemihydrate desulfurization gypsum, and the growth in the C axis direction is inhibited, leading to large crystal size and transformation of crystal shape from long clavate-like to short prismatic or lamellar -shaped. The crystal modifying effect of EDTA is susceptive to pH values, and the optimum pH condition in liquid phase is neutral. EDTA is selectively chemisorbed on the (111) face of gypsum crystal by complex reaction between hydroxyl and
Ca2+, which inhibits the growth of c axis and weackens the relative advantage of the growth rate of in different c–axis directions, consequently leading to the transformation of crystalline habit and crystal morphology of dihydrate gypsum.
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Received: 30 March 2011
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| Fund: Supported by National Nature Science Foundation of China No.50872160. |
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