Flocculation properties and adsorption kinetics of cationic starches in kaolin suspensions |
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Authors: | Yanxiao Chen Shaoying Liu Gongying Wang |
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Affiliation: | 1. Applied Chemistry Department, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China;2. Graduate School of Chinese Academy of Sciences, Beijing 100039, China |
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Abstract: | The flocculation characteristics of cationic starches with degree of substitution (DS 0.32–0.63) have been evaluated in 1.0 wt % kaolin suspension by spectrophotometry and colloid titration. Cationic starch is found to be an effective flocculant for removal of anionic suspension particles. Changes in the electrokinetics of kaolin as a function of pH were investigated in the absence of flocculant. The results show that kaolin in water exhibits a negative surface charge at pH > 2.5. The negative hydrophilic surface sites of kaolin are responsible for the adsorption of cationic starch molecules. The experimental data of the adsorption of cationic starch (DS 0.51) follow a Langmuir isotherm with maximum adsorption capacities of 16.89 mg/g. For the adsorption of cationic starch, chemical reaction seems significant in the rate‐controlling step and the pseudosecond‐order chemical reaction kinetics provides the best correlation for the experimental data. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 |
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Keywords: | cationic starch kaolin flocculation adsorption kinetics isotherms |
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