| 摘要: |
| 研究了四种氨基酸(赖氨酸、谷氨酸、甘氨酸、组氨酸)化合物在改性黏土的吸附特征, 考察了改性剂PACl 添加比例、介质pH 及离子强度对吸附过程的影响, 并探讨了吸附机制。结果表明, 在一定比例的PACl 改性能促进氨基酸在高岭土上的吸附, 最佳改性比例为5%, 赖氨酸、谷氨酸、甘氨酸、组氨酸的最大吸附量分别为827、712.56、723.14、732.56 μmol/g; 氨基酸在改性黏土上的吸附动力学符合伪二阶动力学模型; 利用Weber-Morris 模型测定四种氨基酸内部粒子扩散常数, 5%改性条件下赖氨酸、谷氨酸、甘氨酸、组氨酸的内部粒子扩散常数分别为0.847、0.567、0.780、0.603。热力学研究表明, 氨基酸在改性黏土上的吸附等温线是C 型等温线, 5%改性条件下四种氨基酸(赖氨酸、谷氨酸、甘氨酸、组氨酸)的热力学自由能分别为?1.99、?2.41、?3.16、?2.94 kJ/mol, 说明氨基酸在改性黏土上的吸附是一个自发的吸附过程。介质pH 及离子强度对吸附过程具有重要影响。 |
| 关键词: 氨基酸 改性黏土 动力学 吸附等温线 pH 离子强度 |
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| 基金项目:国家重点基础研究发展计划(973 计划)(2010CB428706);国家自然科学基金青年项目(40906055); 国家自然科学基金创新群体项目(41121064); 河北省省级预算项目(2013045661) |
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| A mechanistic study of the adsorption of amino acid onto modified clays |
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| Abstract: |
| Algal organic materials (AOMs) has critical influence on the REs. Amino acid is an important ingredient of AOMs, for what is with various function groups and is construction units of proteins and polypeptide. In order to obtain a mechanic understanding of the adsorption of amino acid on modified clays, the adsorption of four amino acids, including lysine, glutamic, glycine and histidine, onto modified clays was studied as a function of modifier dosage, pH and ionic strength through well controlled batch adsorption experiments. The kinetics experiments data is fitted well by a pseudo-second order model. The mechanism of amino acid on modified clays is complicated and both the surface adsorption and intraparticle diffusion contribute to the rate determining step. The adsorbed amount of amino acids is increased with adding appropriate dosage of modifier PACl, and the optimum mass ratio is 5%. The maximum adsorption of Lys., Glu., Gly. and His. are 827, 712.56, 723.14 and 732.56 μmol/g, respectively. The equilibrium data is well described by C isotherm curve. The rmodynamic parameters are calculated, e.g. the value of gibbs free energy for Lys., Glu., Gly. and His. are ?1.99, ?2.41, ?3.16 and ?2.94 kJ/mol, respectively. And the results show that the adsorption of amino acid on modified clays is a spontaneous process. The adsorption of amino acid on modified clays is highly dependent on pH, and decreases with increasing ionic strength. |
| Key words: Amino acid Modified clays Adsorption kinetics Adsorption isotherm pH Ionic strength |
