Stability of dispersions of graphitized carbon blacks in aqueous solutions of sodium dodecyl sulphate

Abstract

Measurements have been made of the electrophoretic mobility and the stability of dispersions of two graphitized carbon blacks (Graphon and Sterling MTG) in aqueous solutions of sodium dodecyl sulphate, these carbons having similar adsorption properties but contrasting particle nature. Stability ratios for dispersions containing 0.1 M sodium chloride are compared with predictions of the Deryaguin-Landau-Verwey-Overbeek theory. There is good agreement between experimental and theoretical stability ratios for Graphon, indicating coagulation determined by a potential barrier.Rapid coagulation by Sterling MTG, even at high zeta potentials, is correlated with the secondary minimum. The experimental results suggest that both electrophoretic mobility and stability are determined by the radius of the primary particle rather than that of the total aggregate, as predicted theoretically when the electrical double layer is relatively thin.

Properties of Commercial Nanoparticles that Affect Their Removal During Water Treatment

“…Small particle sizes result in low net energy barriers such that small particles are more unstable than large ones. Previous studies also showed that the values of secondary minima in net interaction energy profiles decreased with decreasing particle sizes and that the aggregation of nanosized particles (which was irreversible) occurred mainly in the primary minima (43)(44)(45)(46). In addition, electrolytes and NOM in water can also affect the stability of colloidal particles by changing their surface charge and compressing their EDLs (37)(38)(39)(47)(48)(49)(50).…”

Intermolecular Force

“…The barrier height is estimated from the measured flocculation rate; other [ ( F i g . Complications arise from the assumption of constant surface potential during aggregation, from doublelayer relaxation during aggregation [145][146][147][148][149], and from nonuniform charge distribution on the particles [150][151][152]. 1-15 The effect of electrolyte concentration on the interaction potential energy between two spheres where K is k in cm À1 .…”

Physicochemical Properties of Carbon Materials: A Brief Overview

“…Heat treatment, which is necessary for structural ordering, is not sufficient for graphitization [6]; the latter process implies that the definite structure of graphite is achieved, and this requires not only exposure to temperatures in excess of 2773 K but also a suitable (graphitizable) precursor and, almost invariably, that the intermediate product passes through a plastic phase (e.g., liquid mesophase). For example, the very much engrained concept of a graphitized carbon black [275][276][277] makes no sense, because carbon blacks are far from being graphitizable.…”