Influence of soluble copper on the electrokinetic properties and transport of copper oxychloride-based fungicide particles

This article describes the influence of dissolved copper on the electrokinetic properties and transport of a copper oxychloride-based fungicide (COF) in porous media. The Zeta potential (ζ) of COF particles increases (viz. becomes less negative) with increasing concentration of Cu2+ in the bulk solution. ζ decreases for COF when the electrolyte (NaNO3) concentration is raised from 1 to 10 mM. This can be ascribed to ion correlation of Cu2+ in the electrical double layer (EDL). COF transport tests in quartz sand columns showed the addition of Cu2+ to the bulk solution to result in increased retention of the metal. Modelling particle deposition dynamics provided results consistent with kinetic attachment. Based on the effect of soluble Cu on colloid mobility, the transport of particulate and soluble forms of copper is coupled via the chemistry of pore water and colloid interactions. Mutual effects between cations and colloids should thus be considered when determining the environmental fate of particulate and soluble forms of copper in soil and groundwater (especially at copper-contaminated sites).

► Soluble copper influences the electrokinetic behavior of copper based fungicide particles.
► Cu2+ and H+ act as charge-determining ions of surfaces.
► A two-site RSA model describes the effect of Cu2+ in the fungicide attachment rate.
► Soluble copper increases the kinetic coefficient of retention of colloids.