Polymer adsorption on mineral surfaces

In the discussion presented previously in this chapter, it has been mentioned that the nature of the solid surface plays an important role in polymer adsorption. For example, it has generally been found that adsorbed amounts of polymer are much higher on carbonates and clay minerals than on sandstone or silica. In the case of the carbonates, this has been attributed to the stronger bonding between Ca (and other multivalent ions) on the surface and the polymer carboxylate groups (Smith, 1970 Lakatos etal, 1979). 

The main mineral substrates that are of interest in oilfield applications of 

The effect of chemical composition of the surface on polymer adsorption has been studied by a number of workers. Sandstones, carbonates, silica and various clay minerals have been used as adsorbent materials (Mungan, 1969 Smith, 1970 Szabo, 1975 Schamp and Huylebroeck, 1973 Lakatos and Lakatos-Szabo, 1980 Lakatos etal, 1979 Willhite and Dominguez, 1977 Bottero etal, 1988 Pefferkorn etal, 1990 Lecourtier etal, 1990 Lee eta/., 1991 Rahbari etal, 1990). 

The adsorption density of polyacrylamides on quartz surfaces has been found by Lecourtier etal (1990) to be generally quite low ( 500/xg/m ) which is attributed to the weak interactions with surface silanols. The adsorption density is found to be independent of pH and salinity for PAM, but increases with salinity and as pH decreases for HPAM (Lecourtier etal, 1990). The changes in xanthan adsorption with salinity and pH are found to be similar to HPAM since both of these are poly anionic species. 

Studies of adsorption of polyacrylamides and xanthans onto kaolinite have appeared recently (Rahbari etal, 1990 Pefferkorn etal, 1990). The adsorption of PAM is high on lateral faces of the kaolinite ( 3500/ig/m ) which is attributed to hydrogen bonding between the carboxyl groups on the polymer and the surface aluminols. However, adsorption of PAM is low on the hydroxide aluminium basal face ( 500/xg/m ) and zero on the siloxan basal face. In contrast, these workers have found that xanthan adsorbs only on 

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