Membrane Fouling Phenomena in Microfluidic Systems: From Technical Challenges to Scientific Opportunities

Abstract

The almost ubiquitous, though undesired, deposition and accumulation of suspended/dissolved matter on solid surfaces, known as fouling, represents a crucial issue strongly affecting the efficiency and sustainability of micro-scale reactors. Fouling becomes even more detrimental for all the applications that require the use of membrane separation units. As a matter of fact, membrane technology is a key route towards process intensification, having the potential to replace conventional separation procedures, with significant energy savings and reduced environmental impact, in a broad range of applications, from water purification to food and pharmaceutical industries. Despite all the research efforts so far, fouling still represents an unsolved problem. The complex interplay of physical and chemical mechanisms governing its evolution is indeed yet to be fully unraveled and the role played by foulants’ properties or operating conditions is an area of active research where microfluidics can play a fundamental role. The aim of this review is to explore fouling through microfluidic systems, assessing the fundamental interactions involved and how microfluidics enables the comprehension of the mechanisms characterizing the process. The main mathematical models describing the fouling stages will also be reviewed and their limitations discussed. Finally, the principal dynamic investigation techniques in which microfluidics represents a key tool will be discussed, analyzing their employment to study fouling.

A Review of Tangential Flow Filtration: Process Development and Applications in the Pharmaceutical Industry

“…TFF processes are categorized into RO, NF, UF, and MF based on the pore size of the membrane used . The different separation mechanisms can be modeled using principles from either solution-diffusion or pore-flow, as listed in Table .…”

Effect of Colloidal Interactions and Hydrodynamic Stress on Particle Deposition in a Single Micropore

“…In these processes, materials flow through various confined geometries such as pipes, nozzles, filters, and membranes. − A colloidal suspension flowing in such a confined geometry often causes clogging, which is an undesirable phenomenon because it degrades process performance and causes various flow problems (e.g., unpredictable deformation of the flow field, increased residence time, and vortex formation) . To understand the clogging mechanism, microfluidics has been widely employed in previous studies because the operational conditions (e.g., geometrical parameters or flow conditions) are easily controlled, and direct observations of clogging dynamics are possible …”

“…16 To understand the clogging mechanism, microfluidics has been widely employed in previous studies because the operational conditions (e.g., geometrical parameters or flow conditions) are easily controlled, and direct observations of clogging dynamics are possible. 17 The clogging mechanism in the microchannel flow can be classified into three types: sieving, bridging, and aggregation, according to the ratio between the pore size and the particle size. 16 Sieving is the simplest clogging mechanism that excludes particles or aggregates larger than the pore size.…”

Design of nanostructured coating to prevent biofilm formation on surfaces

“…For this reason, the biofilm is an ubiquitous structure, and due to its nature is an issue in several industrial and health-related applications, such as contamination of medical equipment (e.g. central venous, urinary catheters, heart valves, intrauterine devices, dental implants [9]), bio-corrosion of industrial equipment, biofouling [10], and crosscontamination of industrial products [7]. A part for biosafety, the most problematic issue is the demanding and expansive removal processes [11].…”