Removal of copper ions using sodium hexadecanoate by ionic flocculation

The mining, electroplating, and electronics industries release increasing amounts of heavy metals, such as copper, into aquatic ecosystems. Industrial effluent often contains metals at concentrations above the maximum limits set by law. In this study, ionic flocculation using the anionic surfactant sodium hexadecanoate is shown to be an alternative method for the removal of copper from industrial effluent. The effects of temperature, metal solution pH, and surfactant concentration on copper removal were analyzed using experimental design techniques. A statistical experimental design of the study showed that the process is directly dependent on the variations in the pH and molar ratio between sodium hexadecanoate and copper ions (Cu2+) but inversely proportional (and less dependent) on the temperature. An individual study of the temperature effect shows that the process is strongly dependent on the Krafft temperature of both surfactants, i.e., that used as the extractive agent and that obtained after the reaction of the surfactant with the metal. Subsequently, the thermodynamic parameters were determined, which showed that the process is spontaneous and either endothermic or exothermic depending on the temperature range.