Contribution to the Adsorption Mechanism of Acetamide and Polyacrylamide on to Clays

Abstract

Abstrac~While studying the retention of additives used in tertiary recovery of petroleum (waterflooding) on minerals present in a rock reservoir, an investigation has been undertaken into the adsorption mechanism of polyacrylamides on to clays. The adsorption of amides and polyacrylamides takes place exclusively on the external surfaces of the clay particles. The organic molecules are protonated on the surface and adsorbed by ionic forces. There is a linear relationship between the adsorption ratio and the polarizing power of the exchangeable cations of the clay mineral. The adsorption isotherms and the thermal analyses reveal the existence of two adsorption mechanisms: (i) a strong, irreversible adsorption, which corresponds to the formation of a monolayer of chemisorbed molecules, (ii) a more important adsorption of molecules retained by hydrogen bonding, which can be eliminated by heating at low temperature. The retention ratio in the irreversible process, which is practically identical both for acetamide and polyacrylamide, is low (3 mg/g). It depends on the external cation exchange capacity (CEC) of the mineral and increases with the surface area. The polyacrylamide adsorption depends on the physico-chemical characteristics of the macromolecule, more particularly on the CONH2/COOratio, which determines the extent of the carbon chain, and the molecular weight. The accessibility of the organic macromolecule to the clay particle is controlled by the preceding factors. The quantity of polyacrylamide irreversibly adsorbed by clay minerals is important in the context of the use of the polymer on a petroleum field. It may be reduced to a minimum by working at low concentrations with a weakly hydrolyzed polyacrylamide solution.

Modified clays for barriers: a review

“…This clay, named HYPER clay, is mixed with a polymeric solution containing the polymer and then dehydrated in an oven at 105°C to irreversibly adsorb the polymer to the clay surface. Dehydration at temperature higher than 60°C has been proven to enhance the irreversible adsorption of the polymer on the clay surface [87]. After HYPER clay treatment, the anionic polymer intercalates in the interlayer region between clay platelets (as demonstrated by XRD analysis by [23]).…”

“…On the other hand, Michaels and Morelos [63] suggested that adsorption is mainly conditioned by hydrogen bonding. A third possibility would originate from the interaction between polyvalent cations acting as crosslinking agents between the clay negative surface and the anionic polymer [87]. In the presence of salts and cations naturally present at the clay surface, the negative charges of the clay and the anionic polymer are shielded from one another allowing the polymer to coil and collapse on the clay surface [14].…”

“…In the presence of salts and cations naturally present at the clay surface, the negative charges of the clay and the anionic polymer are shielded from one another allowing the polymer to coil and collapse on the clay surface [14]. Stutzmann and Siffert [87] compared the quality of the adsorption of anionic polymers on to montmorillonite surface for two scenarios: (a) drying the treated clay either at 60°C and (b) drying under vacuum at 20°C. They found that the adsorption of the polymer on the montmorillonite after drying at 60°C can be considered as intense, irreversible fixation, corresponding to chemisorption.…”

Farklı Anyonik, Katyonik ve Noniyonik Flokülantların İnce Boyutlu Lavvar Tesisi Atıklarının Çökelme Davranışlarına Etkileri

“…Flokülasyon işlemine takiben 15 dk bekledikten sonra, dereceli pipet yardımıyla hava-sıvı ara yüzeyinin yaklaşık 4 cm derinlikten 20 ml numune alınıp bulanıklık değeri türbidimetre yardımıyla tespit edilmiştir. [19].…”

“…Yüksek molekül ağırlığa sahip anyonik flokülantlar, sahip oldukları uzun hidrokarbon zincirleri vasıtasıyla tanelere tutunarak taneler arası köprü oluşturmak suretiyle flok meydana getirmektedirler. Kaolinit tipi kil minerallerinin bulunduğu sistemlerde ise yüzeylere hidrojen bağı ile tutunarak duraylı haldeki kolloidal taneciklerin duraysız olmasını sağlarlar [19,20].…”