Equilibrium studies of the adsorption of aromatic disulfonates by Mg-Al oxide

The removal of m-benzenedisulfonate (BDS2−) and 2,6-naphthalenedisulfonate (NDS2−) anions by Mg-Al oxide was investigated. Langmuir model best describes the adsorption of both aromatic disulfonate anions, with the maximum amount of uptake higher for BDS2−. Mg-Al oxide reacts easier with the aromatic disulfonate anion with higher charge density, a trend that is the opposite of that observed in aromatic sulfonate anions. After increasing the charge from −1 to −2, the removal of aromatic disulfonates by Mg-Al oxide is controlled by electrostatic interactions, instead of hydrophobic interactions that are dominant for aromatic sulfonate anions.