标题： 向更好地理解TiO2纳米颗粒与天然有机物相互作用的团聚机制和热力学性质迈进 显示英文标题

标题： Towards a better understanding on agglomeration mechanisms and thermodynamic properties of TiO2 nanoparticles interacting with natural organic matter

摘要： 工程纳米颗粒与天然有机物之间的相互作用是通过测量结合过程中的交换热量，利用等温滴定量热法进行研究的。 使用二氧化钛锐钛矿型纳米颗粒和藻酸盐作为工程纳米颗粒和天然有机物质，以深入了解吸附和团聚的热力学关联特性和机制。 在二氧化钛纳米颗粒表面带正电荷且藻酸盐表现出负结构电荷的pH值下，确定或计算了焓变、熵变和总自由能、反应化学计量比和亲和结合常数。 我们的结果表明，强的二氧化钛-藻酸盐相互作用主要是熵驱动的，并且在焓变上是有利的，结合反应是放热的。 反应化学计量比和熵增也发现取决于混合顺序。 最后建立了结合焓、反应化学计量比和通过电泳迁移率测量确定的Zeta电位值之间的相关性。 从这些结果中，根据混合顺序提出了两种类型的团聚机制。 发现向二氧化钛分散液中添加藻酸盐由于聚合物桥接而形成团聚体，而向藻酸盐中添加二氧化钛则促进纳米颗粒更单独的包覆。 显示英文摘要

摘要： Interaction between engineered nanoparticles and natural organic matter is investigated by measuring the exchanged heat during binding process with isothermal titration calorimetry. TiO2 anatase nanoparticles and alginate are used as engineered nanoparticles and natural organic matter to get an insight into the thermodynamic association properties and mechanisms of adsorption and agglomeration. Changes of enthalpy, entropy and total free energy, reaction stoichiometry and affinity binding constant are determined or calculated at a pH value where the TiO2 nanoparticles surface charge is positive and the alginate exhibits a negative structural charge. Our results indicate that strong TiO2-alginate interactions are essentially entropy driven and enthalpically favorable with exothermic binding reactions. The reaction stoichiometry and entropy gain are also found dependent on the mixing order. Finally correlation is established between the binding enthalpy, the reaction stoichiometry and the zeta potential values determined by electrophoretic mobility measurements. From these results two types of agglomeration mechanisms are proposed depending on the mixing order. Addition of alginate in TiO2 dispersions is found to form agglomerates due to polymer bridging whereas addition of TiO2 in alginate promotes a more individually coating of the nanoparticles.