Water sorption processes involved

Besides liquid and solid (snow, ice) water surfaces, mineral surfaces play the most important role with respect to adsorption processes involving gaseous organic compounds in the environment. Thus, a brief description of the chemical nature of mineral surfaces is helpful to understand our subsequent discussion of such sorption phenomena. 

A modular pilot size plant involving coagulation/flocculation, centrifugation, ultrafiltration, and sorption processes was designed and constmeted by Benito et al. [13] for the treatment of oily wastewaters. Empirical equations developed by Shaalan [65] predict the impact of water contaminants on flux decline. These formulae enable decision-making concerning a suitable water pretreatment scheme and also selection of the most appropriate cleaning cycle. 

Concerning portland cement, the free lime is the phase most sensitive to moisture uptake (Dubina et al. 2011) see Table 1.1. As the water sorption starts at such a low relative humidity, the transformation of calcium oxide to portlandite cannot really be avoided in practise. Thus, the determination of free lime in clinkers and cements by quantitative XRD should always be verified by other methods, e.g. the extraction method of Franke (1941). From the cement clinker phases the orthorhombic C3A phase is the most sensitive to moisture. The prehydrated surfaces retard further hydration of the clinker grains (Dubina et al. 2011). Calcium silicates and calcium sulfates are involved as well in the prehydration process, as they may take up moisture already at quite low relative humidity. 

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