Membrane Fouling: Microscopic Insights into the Effects of Surface Chemistry and Roughness

Abstract

Fouling is a major obstacle and challenge in membrane‐based separation processes. Caused by the sophisticated interactions between foulant and membrane surface, fouling strongly depends on membrane surface chemistry and roughness. Current studies in the field have been largely focused on polymer membranes. Herein, a molecular dynamics simulation study is reported for fouling on alumina and graphene membrane surfaces during water treatment. For two foulants (sucralose and bisphenol A), it is found that the fouling on alumina surfaces is reduced with increasing surface roughness; however, the fouling on graphene surfaces is enhanced by roughness. It is unravelled that the foulant–surface interaction becomes weaker in the ridge region of a rough alumina surface, thus allowing foulant to leave the surface and reducing fouling. Nevertheless, such behavior is not observed on a rough graphene surface because of strong foulant–graphene interaction. In addition, with increasing roughness, the hydrogen bonds between water and alumina surface are found to increase in number as well as stability. This simulation study reveals that surface chemistry and roughness play a crucial role in membrane fouling, and the microscopic insights are useful for the design of new membranes toward high‐performance water treatment.

CO2 as an Alternative to Traditional Antiscalants in Pressure-Driven Membrane Processes: An Experimental Study of Lab-Scale Operation and Cleaning Strategies

“…The reduced surface roughness found after the filtration cycle may be owing to the deposition of inorganic ions in the valley region. The ionic deposition in ridge and valley zones behaves differently depending on the nature of the foulants and the surface chemistry [ 29 ]. The RMS values were improved after chemical cleaning for different durations ( Figure 9 , Table 2 ), which shows the effectiveness of CP.…”

Constructing highly rough skin layer of thin film (nano)composite polyamide membranes to enhance separation performance: A review

“…37 However, there are papers report the relationship between rough structure and pollution resistance successively in recent years, which is believed to be a great inspiration for the preparation of high-level roughness membranes. [38][39][40] Therefore, this article reviews the reports in recent years in terms of the formation mechanism, strategy, performance comparison and anti-fouling properties of high-roughness membranes, and provides insights for the preparation and application of state-of-the-art membranes.…”

Investigation of membrane fouling using molecular dynamics simulation

“…is too large to be accountable by MD. A recent study by Wang et al [44] attempted to tackle this problem by using idealized graphene and alumina membrane surface with sinusoidal wave shape with a maximum amplitude of 0.5 nm. While the amplitude is insufficient to represent the roughness elements in practical membranes, this setup may lay the groundwork for future MD studies on surface roughness effects.…”

“…( 5) is applied for the foulant, it must be assured that within the time frame studied, the foulant still exhibits a normal diffusion behavior (i.e., an approximate linear relation between MSD and 𝑡) [61,104,109]. Generally, RMSD, especially the z-component that is perpendicular to the membrane surface [44,109], is used to characterize foulant mobility, with a lower value indicating a higher tendency to remain deposited on the membrane surface and thus cause more severe fouling [33,58].…”

“…The LMW portions of NOM refer to molecules with molecular weight less than 350 g/mol [168]. Due to the simple structure, they are also widely used in MD studies as model foulants [44,99]. Virtanen et al [32] simulated the fouling of vanillin on a PES membrane surface.…”