Electrochemical removal of salicylic acid from aqueous solutions using aluminum electrodes Original Research Article

The removal of salicylic acid from aqueous solutions was investigated in an electrochemical cell equipped with aluminum plates by using electrocoagulation (EC). Metal hydroxides generated during EC were used to remove salicylic acid from aqueous solution, and the effects of varying current density and solution temperature on salicylic acid adsorption characteristics were evaluated. The findings indicated that complete salicylic acid removal could be achieved within reasonable removal efficiency and with relatively low electrical energy consumption. The optimum current density and temperature were found to be 1.2 mA cm−2 and 298 K, respectively. Thermodynamic parameters, including the Gibbs free energy, enthalpy, and entropy, indicated that the salicylic acid adsorption of aqueous solutions on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288 K to 318 K. The experimental data were fitted with several adsorption isotherm models to describe the EC process. The adsorption of salicylic acid preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. In addition, the adsorption kinetic studies showed that the EC process was best described using the pseudo-second-order kinetic model at the various current densities and temperatures.