Foulant composition analysis

In the list of requirements in Table 15.1, two of these requirements (in situ fouling assessment, foulant composition analysis) are the main difficulties for process-oriented applications. The online, in situ and in real-time analysis of compositions... 

Performance measurement Pressure drop, flux, conductivity or turbidity Fouling assessment Online, in situ, non-invasive, foulant composition analysis Information acquirement Real time, representative, accurate, reproducible, automatic Device requirement Reliable, user friendly, robust, low cost ... 

Analysis of most crystalline scale deposits and mineral foulants taken from the waterside of cooling systems shows, not unexpectedly, considerable variation in composition. The analysis normally reveals the presence of mixtures of several salts and metal oxides, originally derived from water impurities or corrosion processes. 

The XPS analysis of unwashed membranes showed that ESCA could identify the organic fouling layers of the membranes as well as the surface structure. Peak fitting regimens determined whether the materials discovered were foulants deposited (as indicated by the N (Is) data) on the surface or materials that had become chemically bound to the surface. To be chemically bound to the surface, the foulant must show an oxidation state indicative of a bond with membrane substituents. If the foulant showed a chemical composition not associated with the membrane, it was determined to be lying on the surface (physisorbed) and not chemically attached. This was the case for calcium on LFCl (Ca (2pl, 2p3)BE 350.3-346.9 eV). However, this finding does not preclude the possibility of calcium complexation with functional groups of the RO membranes used... 

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