Department of Earth and Environmental Engineering , Columbia University , New York , New York 10027-6623 , United States.
Department of Chemical and Environmental Engineering , Yale University , New Haven , Connecticut 06520-8286 , United States.
Environ Sci Technol. 2018 Dec 18;52(24):14198-14207. doi: 10.1021/acs.est.8b05768. Epub 2018 Dec 6.
This study investigates the fouling mechanisms in membrane distillation, focusing on the impact of foulant type and membrane surface chemistry. Interaction forces between a surface-functionalized particle probe simulating a range of organic foulants and model surfaces, modified with different surface energy materials, were measured by atomic force microscopy. The measured interaction forces were compared to those calculated based on the experimentally determined surface energy components of the particle probe, model surface, and medium (i.e., water). Surfaces with low interfacial energy exhibited high attractive interaction forces with organic foulants, implying a higher fouling potential. In contrast, hydrophilic surfaces (i.e., surfaces with high interfacial energy) showed the lowest attractive forces with all types of foulants. We further performed fouling experiments with alginate, humic acid, and mineral oil in direct contact membrane distillation using polyvinylidene fluoride membranes modified with various materials to control membrane surface energy. The observed fouling behavior was compared to the interaction force data to better understand the underlying fouling mechanisms. A remarkable correlation was obtained between the evaluated interaction force data and the fouling behavior of the membranes with different surface energy. Membranes with low surface energy were fouled by hydrophobic, low surface tension foulants via "attractive" and subsequent "adsorptive" interaction mechanisms. Furthermore, such membranes have a higher fouling potential than membranes with high or ultralow surface energy.
本研究调查了膜蒸馏中的污垢形成机制，重点关注了污垢类型和膜表面化学性质的影响。通过原子力显微镜测量了模拟一系列有机污染物的表面功能化颗粒探针与用不同表面能材料修饰的模型表面之间的相互作用力。将测量的相互作用力与基于颗粒探针、模型表面和介质（即水）的实验确定的表面能分量计算的相互作用力进行了比较。具有低界面能的表面与有机污染物表现出高吸引力相互作用力，这意味着更高的结垢潜力。相比之下，亲水表面（即具有高界面能的表面）与所有类型的污垢表现出最低的吸引力。我们进一步使用聚偏二氟乙烯膜进行了直接接触膜蒸馏中的褐藻酸钠、腐殖酸和矿物油的结垢实验，使用各种材料来控制膜表面能。将观察到的结垢行为与相互作用力数据进行了比较，以更好地理解潜在的结垢机制。评估的相互作用力数据与具有不同表面能的膜的结垢行为之间存在显著相关性。具有低表面能的膜通过“吸引力”和随后的“吸附”相互作用机制被疏水性、低表面张力的污垢污染。此外，这种膜的结垢潜力高于具有高或超低表面能的膜。
