Comparative study of micro- and ultrafiltration membranes using STM, AFM and SEM techniques

Surface Fouling Characterization Methods for Polymeric Membranes Using a Short Experimental Study

Membrane surface fouling has always been a critical issue for the long-term operation of polymeric membranes. Therefore, it is crucial to develop new approaches to prevent fouling. While developing new approaches, characterization methods are greatly important for understanding the distribution of fouling on the membrane surface. In this work, a cellulose acetate membrane was fouled by the filtration of artificial wastewater based on alginate. The surfaces of fouled membranes were characterized through scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), and white light interferometry (WLI). The results were then compared in terms of the resolution, accuracy, feasibility, and cost-efficiency.

Non-invasive study of the three-dimensional structure of nanoporous triblock terpolymer membranes

Nanoporous media are of great importance for drug delivery or filtration. Typically the pore structure of such media is characterized using high-resolution techniques such as electron microscopy or atomic force microscopy. However, these techniques are restricted to the surface of the material and/or are highly invasive. In a proof-of-concept experiment we have employed three-dimensional single-particle orbit tracking for testing the three-dimensional pore structure of a liquid filled nanoporous polystyrene-block-polyisoprene-block-poly(N-isopropylacrylamide) (PS-b-PI-b-PNiPAAm) triblock terpolymer membrane. Using fluorescent tracers with a diameter of about 10% of the relevant void structures, the tracking experiments yielded results that were comparable to those obtained from reference experiments using environmental scanning electron microscopy (eSEM). This testifies that single-particle orbit tracking can serve as a useful non-invasive alternative for characterising the structure of nanoporous materials.

Understanding flux patterns in membrane processing of protein solutions and suspensions

Membrane microfiltration is one of the most effective ways of separating proteins from materials of larger size, such as microbial cells and cell debris. Ultrafiltration is the most effective means of concentrating protein solutions. This review describes the scope and operating patterns of these processes. A major goal for membrane technologists is the development of predictive descriptions of membrane processes, based on a rigorous understanding of the underlying physico-chemical phenomena. The emphasis is placed on quantitative analysis of the interfacial aspects and microhydrodynamics of membrane processes. From existing knowledge, it is already possible to define a number of guidelines for successful filtration process operation.