Assessment of an Intrinsic Optical Fiber Sensor for 'in situ' Monitoring of Scale-Forming Salts

An exposed fiber core (EFC) method employing poly(methyl methacrylate) optical fibers was used to monitor the formation of calcium oxalate monohydrate scale under laboratory conditions using the phenomenon whereby development of a high-refractive-index scale coating on the fiber surface attenuated the guided radiation in the fiber core. Formation of scale on the optical fibers was verified by scanning electron microscopy. The results obtained by this method were comparable to results obtained from turbidity and conductivity measurements, but whereas these latter methods rely on phenomena in the bulk that might or might not be relevant to the kinetics of scaling per se, the optical fiber method directly interrogates phenomena at the solid/liquid interface.