水杨酸及其磺基衍生物在超高交联吸附树脂上的吸附选择性研究

Dsorption selectivity of salicylic acid and sulfonic derivativres onto hypercrosslinked polymeric adsorbents

水杨酸及其磺基衍生物(5-磺基水杨酸)在超高交联吸附树脂NDA-100和改性超高交联吸附树脂NDA-99上的平衡吸附遵循Freundlich等温方程,拟合结果表明其放热的优惠吸附特征。NDA-100树脂的吸附主要依赖π-π作用,而5-磺基水杨酸在NDA-99上的吸附受静电作用的影响明显。随着双组分体系内5-磺基水杨酸初始浓度的增大,水杨酸在NDA-99上的吸附量减小,而在NDA-100上的吸附量增大。另外对于两种树脂,随着水杨酸初始浓度的增大,5-磺基水杨酸的吸附量均减小。吸附作用力的强弱导致溶质组分在树脂活性位点上的直接竞争现象。在5-磺基水杨酸存在的吸附体系内,NDA-100对水杨酸的吸附选择性远远优越于NDA-99。NDA-100串联NDA-99组合吸附工艺可以有效实现水杨酸和5-磺基水杨酸的选择性吸附分离。

The Freundlich model can successfully describe all the adsorption isotherms tested involving salicylic acid and sulfonic derivatives（5-sulfosalicylic acid）,which indicates a favorable and exothermic adsorption process. The adsorption of salicylic acid relies on π-π interaction,while the electrostatic interaction further influences the adsorption of 5-sulfosalieylie acid onto NDA-99. The adsorptive capacity of salicylic acid decreases on NDA-99 while increases on NDA-101 with 5-sulfosalicylic acid as the background component in a binary solute system. The adsorption amount of 5-sulfosalicylic acid decreases with the initial concentration of salicylic acid increasing on both adsorbents. The competition for the adsorption sites is considered predominant in the solid-to-liquid interaction process, as resulted from thedifference in the affinity to the solid phase. The adsorption selectivity of salicylic acid onto NDA-101 is over a magnitude degree larger than onto NDA-99. Thus,the combinatorial technique involving NDA-101 followed by NDA-99 canbe successfully applied to separate salicylic acid and 5-sulfosalicylic acid from aqueous media.