Nonionic surfactants on quartz

Adsorption of Nonionic Surfactants on Quartz in the Presence of Ethanol, HCl, or CaCl2... 

The cationic surfactants strongly adsorb on reservoir silicates or quartz, which can be lowered by incorporating nonionic surfactants in the formulation. The adsorption of cationic surfactants on quartz is usually about 0.5 x 10 mg/cm. On the other hand, the nonionic surfactants adsorb slightly on quartz surfaces, but adsorption increases with raising temperature. The nonionic surfactants adsorb more on oil-wetted than water-wetted reservoir silicate surfaces. 

A characteristic of the early neutron reflectivity studies of nonionic surfactant adsorption was some variability in the pattern of adsorption. This was investigated in more detail and more systematically by McDermott et al. [55], who compared the adsorption of Ci2E6 onto a range of different substrates, amorphous silica, crystalline quartz, and the oxide layer on a silicon single crystal. The adsorbed surfactant was found to form a bilayer with an overall thickness 49 4 A, with a structure similar to that determined in the previous studies (see Fig. 4). 

Quartz can be floated by cationic surfactant dodecyla-mine hydrochloride. Nonionic polymer, polyacrylamide (PAM), which does not adsorb on quartz and does not cause flotation by itself, increases the quartz flotation by amine slightly due to the uptake of water molecules by the polymer for hydration. The hydration of polymer causes an increase in the effective concentration of amine. 

To study the effect of surfactants, rates of evaporation of a nonionic surfactant solution from single quartz capillaries with radii from 10 to 20 pm were measured [15]. The results obtained for evaporation of pure water (curve 1) and 0.25% solution of syntamide-5 (curve 2) from capillaries of equal radii, r = 8.2 pm, are shown in Fig. 12. Here L is the distance of evaporating meniscus from the open capillary end and t is the time. The capillaries filled with water and with surfactant solutions, respectively, were placed in an evacuated chamber [16] near each other. Curves 1 and 2 refer to evaporation in vacuum (p/ps = 0) at A = 5 x 10 " cm /s, where K is the coefficient characterizing the rate of evaporation. The coefficient K = L j4t depends on external conditions of evaporation and is proportional to the difference between vapor pressure over meniscus, p , and in surrounding media, po-At first, the curves 1 and 2 practically coincide, but later on evaporation from the capillary filled with the surfactant solution gradually slows down. This can be explained by the concentration of surfactant molecules near the evaporating meniscus surface. 

The Effect of Adsorption on the Levels of Surfactant in Injection Fluids -- From the results of Figures 4 and 5 it is possible to assess the changes in the concentration of surfactant as a consequence of its adsorption on the minerals forming the reservoir. The results reported in this paper are for quartz, silica, or glass nevertheless, these solids probably represent the worst cases, because the adsorption of nonionics on alumina (and by extension onto alumino silicates) and on calcareous minerals is lower than the adsorption onto quartziferous materials (G. Gonzalez, A. Travalloni, in progress). 

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