Campinas Margarida, Rosa Maria João
Centre of Marine and Environmental Research, Faculty of Marine and Environmental Sciences, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
J Colloid Interface Sci. 2006 Jul 15;299(2):520-9. doi: 10.1016/j.jcis.2006.02.042. Epub 2006 Apr 17.
This work aims to contribute to a better understanding of the ionic strength effect on microcystin and natural organic matter (NOM) surrogate adsorption by analyzing the importance of adsorbate molecular size, and surface concentration. Adsorption kinetics and/or isotherms were performed on PAC Norit SA-UF for four microcystin variants (MC-LR, MC-LY, MC-LW, MC-LF), and three NOM surrogates (salicylic acid (SA), tannic acid (TA), Aldrich humic acid (AHA)) at different solution ionic strengths. Results showed that the ionic strength effect depends upon the adsorbate surface concentration, cation charge (mono or divalent), and adsorbate molecular size. Potassium seemed not to affect the MC-LR adsorption, while calcium enhanced MC-LR kinetics and adsorption capacity. K+ and, particularly, Ca2+ improved the adsorption kinetics of the other microcystin variants. For identical surface concentration and ionic strength, the impact of K+ and Ca2+ on NOM surrogates depended on the adsorbate molecular size: K+ effect was only observed for AHA, whereas Ca2+ caused no effect on SA adsorption, slightly enhanced TA adsorption, and greatly enhanced AHA adsorption. MC-LR isotherms with two salt concentrations (KCl or CaCl2) indicated that, for the studied range of equilibrium surface concentration (5.3-18.7 mg/g), an enhanced adsorption regime prevails, and no transition regime was observed.
本研究旨在通过分析吸附质分子大小和表面浓度的重要性，更好地理解离子强度对微囊藻毒素和天然有机物（NOM）替代物吸附的影响。在不同溶液离子强度下，对诺芮特SA-UF活性炭进行了四种微囊藻毒素变体（MC-LR、MC-LY、MC-LW、MC-LF）和三种NOM替代物（水杨酸（SA）、单宁酸（TA）、奥尔德里奇腐殖酸（AHA））的吸附动力学和/或等温线实验。结果表明，离子强度效应取决于吸附质表面浓度、阳离子电荷（单价或二价）和吸附质分子大小。钾似乎不影响MC-LR的吸附，而钙增强了MC-LR的动力学和吸附容量。K+，尤其是Ca2+改善了其他微囊藻毒素变体的吸附动力学。对于相同的表面浓度和离子强度，K+和Ca2+对NOM替代物的影响取决于吸附质分子大小：K+的影响仅在AHA中观察到，而Ca2+对SA吸附没有影响，对TA吸附略有增强，对AHA吸附有很大增强。两种盐浓度（KCl或CaCl2）下的MC-LR等温线表明，在所研究的平衡表面浓度范围（5.3-18.7 mg/g）内，存在增强吸附区，未观察到转变区。
