Study of Ca-ATMP precipitation in the presence of magnesium ion

ATMP (aminotri(methylenephosphonic acid)), a phosphonate scale inhibitor used in the petroleum industry, was used as a model scale inhibitor in this study. One of the goals of this work was to determine the range of conditions under which Mg ions, which are formed in reservoir formations containing dolomite, modulate the formation of Ca-ATMP precipitate as a scale inhibitor. The results revealed that the amount of ATMP precipitated decreased with addition of Mg ions in solution at all values of the solution pH. Furthermore, an increase in both the solution pH and the concentration of the divalent cations in solution resulted in a change of the molar ratio of (Ca + Mg) to ATMP in the precipitates. At a low solution pH (pH 1.5), Mg ions had little effect on the composition of the Ca-ATMP precipitate. However, at higher values of the solution pH (pH 4 and 7), the Ca to ATMP molar ratio in the precipitates decreased with increasing concentration of the Mg. Here it was found that Mg ions replaced Ca ions on available reactive sites of ATMP molecules. These results determined the limits of the Mg ion concentration, which affects the precipitation of Ca-ATMP, Mg-ATMP, and (Ca + Mg)-ATMP. The dissolution of the scale inhibitors was studied using a rotating disk reactor. These experiments showed that the total divalent cation molar ratio (Ca + Mg) to ATMP in the precipitates is the primary factor that controls the rate of dissolution (release) of the phosphonate precipitates. The phosphonate precipitate dissolution rates decreased as the molar ratio of divalent cations to ATMP in the precipitates increased.     

Adsolubilization of toluene and acetophenone as a function of surfactant adsorption

Adsolubilization, solubilization of organic compounds into adsorbed surfactant aggregates, has attracted much attention in the past few years. It is being explored for a variety of new commercial applications including the formation of engineered surfaces, pharmaceutical applications, and nanotechnology. Adsolubilization is strongly influenced by the amount of adsorbed surfactant, which in turn depends upon pH, ionic strength, and surfactant type and concentration. In this study, the adsorption of a cationic surfactant, cetyltrimethylammonium bromide (CTAB) on precipitated silica and the adsolubilization of organic solutes (toluene and acetophenone) into the adsorbed surfactant aggregates were examined as a function of surfactant adsorption at two pH values (5 and 8). Three levels of surfactant adsorption, corresponding to equilibrium concentration low in region II, high in region II, and low in region III of the adsorption isotherm, and the adsolubilization of toluene and acetophenone were investigated both in single- and mixed-solute systems. The results showed that the adsorption of CTAB depended strongly on pH and for each pH the adsolubilization increased with increasing surface adsorption. However, the adsolubilization behaviors of the adsorbed CTAB aggregates in different adsorption regions were quite distinct, suggesting that the structural arrangement of the surfactant aggregates may play an important part in addition to the amount of adsorbed surfactant. This phenomenon was more noticeable at low surfactant adsorption than at higher surface adsorption. In mixed-solute systems, the presence of acetophenone had little effect on the toluene adsolubilization. In contrast, a synergetic effect was observed in the adsolubilization of acetophenone in the presence of toluene.     

Effect of Soxhlet Extraction and Surfactant System on Morphology and Properties of Poly(DVB)PolyHIPE

Poly(Divinylbenzene)PolyHIPE (Poly(DVB)PolyHIPE) was successfully prepared by using two different systems of three-component surfactants (S20M and S80M) and toluene as porogenic solvent. Phase morphology, mechanical properties and surface area measurements of the obtained Poly(DVB)Poly HIPE were investigated. After polymerization of continuous phase followed by extraction process, the porous materials (open cellular structure with interconnections) were obtained. The cell size and surface area were found to be improved: this is due to the ability of porogenic solvent and mixture of the surfactants to prevent the Ostwald ripening (coalescence) of the emulsion droplet system. Moreover, the surface area and mechanical properties of the resulting materials were found to be depended on the Soxhlet extraction time. It was demonstrated that the usage of Soxhlet extraction technique for Poly(DVB)PolyHIPE improved surface area of the obtained materials by 107% as compared with the unextracted PolyHIPE. However, when the extraction time was longer than 12 hours, the properties of the obtained materials became poor. It was concluded that the suitable Soxhlet extraction time for Poly(DVB)PolyHIPE was 6–12 hours and at this condition, high surface area with the highest mechanical properties of the porous material were obtained.