Kinetics and mechanism of sorption of chloride ion from sodium carbonate manufacturing wastewater by Mg-Al oxide

In this article, the removal of chloride ion generated from industrial wastewater was examined by using magnesium-aluminum (Mg-Al) oxide obtained from Mg-Al layered double hydroxide. The influences of conditions for chloride ion uptake, including quantity of Mg-Al oxide, contact time and temperature on anion exchange has been investigated, respectively. The extent of the chloride, ion removal increased with an increase in the quantity of Mg-Al oxide, contact time, and temperature. Thermodynamic parameters including Gibbs free energy ( increment G degrees), standard enthalpy change ( increment H degrees), and standard entropy change ( increment S degrees) for the process were calculated using the Langmuir constants. Kinetic analyses were conducted using pseudo-first and second-order models. The regression results showed that the uptake process was more accurately represented by pseudo-second-order model. The calculated value of E-a was found to be 77.428 kJ/mol, which indicate that the process of uptake of chloride ion is controlled by the rate of reaction of chloride ion with the Mg-Al oxide rather than diffusion. Results suggested that the uptake process was feasible and endothermic.