Adsorption characterizations of fulvic acid fractions onto kaolinite.
Adsorption characterizations of fulvic acid fractions onto kaolinite.
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DOI：
10.1016/s1001-0742(08)62090-2
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发表时间：
2008
影响因子：
6.9
通讯作者：
Aimin Li;Minjuan Xu;Wenhui Li;Xuejun Wang;Jing-yu Dai
中科院分区：
文献类型：
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作者：
Aimin Li;Minjuan Xu;Wenhui Li;Xuejun Wang;Jing-yu Dai
从中国太湖水稻产区提取的黄腐酸分别用pH 4.8缓冲液、pH 7.0缓冲液和pH 11.0缓冲液洗脱，得到F4.8、F7.0和F11.0三个组分。通过间歇吸附实验研究了高岭石对黄腐酸(FA)组分的吸附，并用扫描电子显微镜(SEM)对吸附前后的高岭石进行了表征。高岭石对三种FA组分的吸附等温线符合Langmuir吸附模型。三种馏分的吸附密度与脂肪酸馏分中烷基碳与羧基和羰基碳的比值呈正相关，且顺序为F11.0>；F7.0>；F4.8。疏水相互作用是高岭石吸附FA组分的控制机制之一。扫描电子显微镜照片证实，与空白高岭石样品相比，经FA包覆的高岭石样品由于复合体中絮体结构的破坏，呈现出更开放、更分散的构象。吸附后高岭石的分散是由于带负电的FA包覆颗粒之间的相互排斥作用所致，这与高岭石吸附FA组分的量密切相关。
Fulvic acids extracted from a typical rice-production region near Taihu Lake of China were fractionated into three fractions including F4.8, F7.0 and F11.0 (eluted by pH 4.8 buffer, pH 7.0 buffer and pH 11.0 buffer, respectively). Sorption of fulvic acid (FA) fractions onto kaolinite was studied by batch adsorption experiments, and characterizations of kaolinite before and after adsorption were investigated using scanning electron microscopy (SEM). Adsorption isotherms of kaolinite for three FA fractions fit well with the Langmuir adsorption model. The adsorption density of the three fractions was positively correlated with the ratio of the amount of the alkyl carbon to that of carboxyl and carbonyl carbon in FA fractions and followed an order of F11.0 > F7.0 > F4.8. Hydrophobic interaction was one of the control mechanisms for the sorption of FA fraction onto kaolinite. SEM images confirmed that compared to blank kaolinite samples, kaolinite samples coated by a FA fraction displayed an opener and more dispersed conformation resulting from the disruption of the floc structure in complex. Dispersion of kaolinite after adsorption was due to the repulsion between negatively charged FA-coated particles, which is closely related to the amount of FA fractions absorbed on kaolinite.