Experimental–Theoretical Approach to the Adsorption Mechanisms for Anionic, Cationic, and Zwitterionic Surfactants at the Calcite–Water Interface

Abstract

The adsorption of surfactants (DTAB, SDS, and CAPB) at the calcite-water interface was studied through surface zeta potential measurements and multiscale molecular dynamics. The ground-state polarization of surfactants proved to be a key factor for the observed behavior; correlation was found between adsorption and the hard or soft charge distribution of the amphiphile. SDS exhibits a steep aggregation profile, reaching saturation and showing classic ionic-surfactant behavior. In contrast, DTAB and CAPB featured diversified adsorption profiles, suggesting interplay between supramolecular aggregation and desorption from the solid surface and alleviating charge buildup at the carbonate surface when bulk concentration approaches CMC. This manifests as an adsorption profile with a fast initial step, followed by a metastable plateau and finalizing with a sharp decrease and stabilization of surface charge. Suggesting this competition of equilibria, elicited at the CaCO3 surface, this study provides atomistic insight into the adsorption mechanism for ionic surfactants on calcite, which is in accordance with experimental evidence and which is a relevant criterion for developing enhanced oil recovery processes.

Synthesis and structures of zwitterionic polymers to induce electrostatic interaction with PDMS surface treated by air-plasma

“…31 In polymer coating, the electrostatic interaction sometimes plays crucial role to afford a durable modified surface by formation of polyion-complexes. [32][33][34] Furthermore, it is reported that annealing treatment of coating surface with polymers enhances electrostatic interaction by structural arrangement of polymers due to their flexibility. 35 The surface of PDMS treated by air-plasma is known to be silica-like, but the molecule at the surface seems to be flexible enough to recover hydrophobicity.…”

Antiradical Properties of N-Oxide Surfactants—Two in One

“…The positive and negative charge is strongly localized on nitrogen and oxygen atoms, respectively. As discussed by Durán-Álvarez et al [ 20 ], such a strong charge localization reflects a hard electrostatic nature of atoms being the charge carriers in C n (DAPANO) 2 and C n PDA. There is, however, an important difference in charge distribution between C n (DAPANO) 2 and C n PDA.…”

Templating Interfacial Nanoparticle Assemblies via in Situ Techniques

“…Although ζ-potential and X-ray measurements corroborate the adsorption of negative amphiphiles to particles of the same charge, the exact mechanism was not discussed . Possibly related to this is the study by Durán-Álvarez . Through streaming potential measurements and molecular dynamics simulations, they found that the adsorption of positively charged dodecyltrimethylammonium bromide (DOTAB) on positively charged calcite depends upon electrostatic screening by counterions and water molecules.…”