开放系统下丙二酸在方解石上的吸附

Sorption of malonate onto calcite in open-system

通过批量平衡法,研究开放系统条件下方解石对丙二酸的吸附特性.结果表明,丙二酸在方解石上的吸附先快后慢,3 h后渐趋平衡;当pH值从7.7增加到9.7时,丙二酸的吸附率逐渐降低,HCO-3和CO2-3的竞争效应及方解石表面的静电效应是其主导因素;同一初始浓度下,与开放系统条件比较,半封闭系统条件下丙二酸的吸附量显著降低,推测其原因是半封闭系统中OH-的竞争作用.丙二酸与邻苯二甲酸的等温吸附结果对比发现,丙二酸的吸附能力较邻苯二甲酸更强,丙二酸的等温吸附过程符合Langmuir模型,而邻苯二甲酸的等温吸附过程更符合Freundlich模型,推测以上差异是由两羧基之间的分子结构不同引起的.

Batch methods were deployed to study the sorption of malonate on calcite in open-system.Results show that： malonate sorption increased rapidly with time initially and then reached between equilibrium within 3 hours. The malonate sorption rate decreased with in pH 7. 7—9. 7. This is due to the competition effect of HCO3^-and CO3^2-,and the electrostatic effect on the surface; At the same initial concentration,compared to open-system,the malonate adsorption quantity in half-closed system was relatively small,which may be due to the obvious competition effect of OH^-in halfclosed system. Compared with o-phthalate,malonate sorption capacity was higher and its sorption isotherm was better described by Langmuir model. The sorption isotherm of o-phthalate was better described by Freundlich model. These differences may be attributed to the different structures between their two carboxyl groups.