De Luca G, Bisignano F, Figoli A, Galiano F, Furia E, Mancuso R, Saoncella O, Carraro M, Bonchio M, Gabriele B
Research Institute on Membrane Technology (ITM-CNR), University of Calabria , Via P. Bucci, I-87036 Arcavacata di Rende (CS), Italy.
J Phys Chem B. 2014 Mar 6;118(9):2396-404. doi: 10.1021/jp411401v. Epub 2014 Feb 26.
Noncovalent interactions between the polyoxometalate PMo12O40 and acryloyloxyundecyltrimethyl ammonium bromide surfactant, used during membrane preparation, were evaluated in the frame of density functional theory. The electronic solvation energy of PMo12O40 and bromide anions was also evaluated, at the same level of theory, in order to predict a probable exchange on the polymeric surface between these anions at the water/polymer interface. Energy balances were theoretically assessed, showing that the bromide cannot be exchanged with this nanosized polyanion in large extent. In order to validate this theoretical conclusion, ad hoc and accurate measurements were carried out by using homemade polymeric membranes and by dipping them in an ca. 0.4 mM solution of Na3[PMo12O40] for 4 days. The Br(-) concentration, released in a polyoxometalate solution, was followed at different times during the test period by gravimetrical analysis. The agreement between the theoretical prediction and experimental data was remarkable, as the quantum calculations correctly accounted for the short-range intermolecular interactions involved in this phenomenon. Bearing in mind that the achieved conclusion is based on an ab initio quantum approach, the findings of this study can be considered rather general and then exploitable for other similar systems.
在密度泛函理论框架下，评估了在膜制备过程中使用的多金属氧酸盐PMo12O40与丙烯酰氧基十一烷基三甲基溴化铵表面活性剂之间的非共价相互作用。还在相同理论水平下评估了PMo12O40和溴离子的电子溶剂化能，以预测在水/聚合物界面处这些阴离子在聚合物表面上可能发生的交换。从理论上评估了能量平衡，结果表明溴离子不能与这种纳米尺寸的聚阴离子大量交换。为了验证这一理论结论，使用自制的聚合物膜并将其浸入约0.4 mM的Na3[PMo12O40]溶液中4天，进行了专门且精确的测量。在测试期间的不同时间，通过重量分析跟踪多金属氧酸盐溶液中释放的Br(-)浓度。理论预测与实验数据之间的一致性非常显著，因为量子计算正确地解释了该现象中涉及的短程分子间相互作用。鉴于所达成的结论基于从头算量子方法，本研究的结果可被视为相当普遍，进而可用于其他类似系统。
