Atomic Force Microscopy (AFM)

The use of atomic force microscopy (AFM) has been increasingly used in recent years in academic research labs to probe the surface morphology and physical properties of a wide range of surfaces at high resolution, including surfaces pertinent to water treatment processes, particularly polymer membranes. The AFM at its heart is based around a very sharp imaging probe, which is scanned over the surface of interest, allowing a three-dimensional map to be generated. Its utility lies in its versatility, being able to make measurements in both ambient and liquid environments, unlike many other high-resolution imaging techniques. In addition, the physical interaction between the probe and the surface of interest allows the measurement of surface forces, of great interest when studying the mechanisms of attachment of foulants and biofoulants to membranes. By changing the surface chemistry of the probe tip, or by replacing the imaging probe with a functionalized microparticle, a great number of surface interactions can be investigated in a wide range of environments mimicking process conditions. In this chapter we will endeavor to give a general overview, with examples from the scientific literature, of the measurements and investigations, which may be made into the characteristics of membranes engineered for separation processes using the AFM.