Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Saudi Arabia.
Curtin Water Quality Research Centre, Department of Chemistry, Curtin University, Australia; Facultad del Mar y Medio Ambiente, Universidad Del Pacifico, Guayaquil, Ecuador.
Water Res. 2017 Jun 1;116:194-202. doi: 10.1016/j.watres.2017.03.034. Epub 2017 Mar 21.
In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO or AlO, were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms. However, the magnitude of these forces was significantly higher on ZrO surfaces, irrespective of cation type (Na or Ca) or concentration. Interestingly, while HMW SKC-EOM interacting forces to AlO were practically insensitive to solution chemistry, the interactions between ZrO and HMW SKC-EOM increased with increasing cation concentration in solution. The structure, and lower charge, hydrophilicity, and density of hydroxyl groups on ZrO surface would play a key role on favoring zirconia associations with HMW SKC-EOM. The current results contribute to advance our fundamental understanding of Algogenic Organic Matter (AOM) interfacial interactions with metal oxides (i.e., AOM membrane fouling), and would highly assist in the proper selection of membrane material during episodic algal blooms.
在当前的研究中，通过原子力显微镜（AFM）研究了中分子量（HMW）角毛藻胞外有机物（EOM）与 ZrO 或 AlO 的界面相互作用。HMW 角毛藻-EOM 经过严格的特性描述，被确定为主要由多糖样结构组成的亲水有机化合物。尽管含量较低，但也观察到了脂质和蛋白质。在所有测试的溶液条件下，HMW 角毛藻-EOM 在接近（即导致跳跃接触事件）和回缩阶段都表现出吸引力和粘附力，静电和氢键被认为是主要的相互作用机制。然而，在所有测试的溶液条件下，这些力的大小在 ZrO 表面上明显更高，而与阳离子类型（Na 或 Ca）或浓度无关。有趣的是，虽然 HMW 角毛藻-EOM 与 AlO 的相互作用力对溶液化学几乎不敏感，但 ZrO 与 HMW 角毛藻-EOM 之间的相互作用随着溶液中阳离子浓度的增加而增加。ZrO 表面的结构、较低的电荷、亲水性和羟基密度在有利于与 HMW 角毛藻-EOM 形成锆化合物方面发挥着关键作用。目前的研究结果有助于深入了解 Algogenic Organic Matter（AOM）与金属氧化物（即 AOM 膜污染）的界面相互作用，并将在藻类爆发期间正确选择膜材料方面提供很大帮助。
