Laboratoire de Physique de la Matière Condensée, Faculté des Sciences de Tunis, Campus Universitaire, 2092 El Manar, Tunisia.
Dipartimento di Scienze Fisiche e Chimiche, Università dell'Aquila, Via Vetoio 10, I-67100 L'Aquila, Italy.
J Chem Phys. 2020 Mar 21;152(11):114102. doi: 10.1063/1.5139291.
Light-to-heat conversion in plasmonic nanoparticles (NPs) inside polymeric membranes is beneficial for improving the efficiency of membrane distillation for seawater desalination. However, the physical mechanisms ruling photothermal membrane distillation are unclear yet. Here, we model the plasmonic photothermal light-to-heat conversion from Ag, Au, and Cu nanofillers in polymeric membranes for membrane distillation. Photothermal effects in the cases of isolated metallic NPs and their assembly are investigated considering size effects and excitation sources. The increasing content of metallic NPs improves the efficiency of the light-to-heat conversion. For a polymeric membrane, filled with 25% Ag NPs, our model well reproduces the experimental temperature increase of 10 K. Specifically, we find that Ag NPs with a radius of around 30-40 nm are favorite candidates for membrane heating with excitation energy in the visible/near-UV range. The incorporation of a term associated with heat losses into the heat transfer equation well reproduces the cooling effect associated with vaporization at the membrane surface. Compared to Ag NPs, Au and Cu NPs show a broadened absorption cross section and their resonance has a nonlinear behavior with varying the excitation energy, better matching with sunlight radiation spectrum.
光热转换在聚合物膜内的等离子体纳米粒子（NPs）中对于提高膜蒸馏海水淡化的效率是有益的。然而，光热膜蒸馏的物理机制尚不清楚。在这里，我们对聚合物膜中的 Ag、Au 和 Cu 纳米颗粒的等离子体光热光热转换进行建模，用于膜蒸馏。考虑到尺寸效应和激发源，研究了孤立金属 NPs 及其组装体的光热效应。金属 NPs 含量的增加提高了光热转换效率。对于填充有 25%Ag NPs 的聚合物膜，我们的模型很好地再现了实验中 10 K 的温度升高。具体来说，我们发现半径在 30-40nm 左右的 Ag NPs 是在可见光/近紫外范围内激发能量下用于膜加热的理想候选材料。将与热损失相关的项纳入传热方程可以很好地再现与膜表面蒸发相关的冷却效应。与 Ag NPs 相比，Au 和 Cu NPs 具有较宽的吸收截面，其共振具有随激发能量变化的非线性行为，更好地匹配太阳光辐射光谱。
